[v4,1/5] thermal: Add generic cpufreq cooling implementation

This patch adds support for generic cpu thermal cooling low level
implementations using frequency scaling up/down based on the registration
parameters. Different cpu related cooling devices can be registered by the
user and the binding of these cooling devices to the corresponding
trip points can be easily done as the registration APIs return the
cooling device pointer. The user of these APIs are responsible for
passing clipping frequency . The drivers can also register to recieve
notification about any cooling action called.

Signed-off-by: Amit Daniel Kachhap <amit.kachhap@linaro.org>
---
 Documentation/thermal/cpu-cooling-api.txt |   60 ++++
 drivers/thermal/Kconfig                   |   11 +
 drivers/thermal/Makefile                  |    3 +-
 drivers/thermal/cpu_cooling.c             |  483 +++++++++++++++++++++++++++++
 include/linux/cpu_cooling.h               |   99 ++++++
 5 files changed, 655 insertions(+), 1 deletions(-)
 create mode 100644 Documentation/thermal/cpu-cooling-api.txt
 create mode 100644 drivers/thermal/cpu_cooling.c
 create mode 100644 include/linux/cpu_cooling.h

Hey Amit,

I was just re-organizing the imx thermal driver that uses this cpu
cooling interface and noticed a couple of small issues here.   If
these suggestions are agreed upon and if it's too late for these
issues be changed with this patchset, I can submit them separately
unless you'd prefer to.

On Sat, May 12, 2012 at 4:40 AM, Amit Daniel Kachhap
<amit.kachhap@linaro.org> wrote:
> This patch adds support for generic cpu thermal cooling low level
> implementations using frequency scaling up/down based on the registration
> parameters. Different cpu related cooling devices can be registered by the
> user and the binding of these cooling devices to the corresponding
> trip points can be easily done as the registration APIs return the
> cooling device pointer. The user of these APIs are responsible for
> passing clipping frequency . The drivers can also register to recieve
> notification about any cooling action called.
>
> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@linaro.org>
> ---
>  Documentation/thermal/cpu-cooling-api.txt |   60 ++++
>  drivers/thermal/Kconfig                   |   11 +
>  drivers/thermal/Makefile                  |    3 +-
>  drivers/thermal/cpu_cooling.c             |  483 +++++++++++++++++++++++++++++
>  include/linux/cpu_cooling.h               |   99 ++++++
>  5 files changed, 655 insertions(+), 1 deletions(-)
>  create mode 100644 Documentation/thermal/cpu-cooling-api.txt
>  create mode 100644 drivers/thermal/cpu_cooling.c
>  create mode 100644 include/linux/cpu_cooling.h
>
> diff --git a/Documentation/thermal/cpu-cooling-api.txt b/Documentation/thermal/cpu-cooling-api.txt
> new file mode 100644
> index 0000000..557adb8
> --- /dev/null
> +++ b/Documentation/thermal/cpu-cooling-api.txt
> @@ -0,0 +1,60 @@
> +CPU cooling APIs How To
> +===================================
> +
> +Written by Amit Daniel Kachhap <amit.kachhap@linaro.org>
> +
> +Updated: 12 May 2012
> +
> +Copyright (c)  2012 Samsung Electronics Co., Ltd(http://www.samsung.com)
> +
> +0. Introduction
> +
> +The generic cpu cooling(freq clipping, cpuhotplug etc) provides
> +registration/unregistration APIs to the caller. The binding of the cooling
> +devices to the trip point is left for the user. The registration APIs returns
> +the cooling device pointer.
> +
> +1. cpu cooling APIs
> +
> +1.1 cpufreq registration/unregistration APIs
> +1.1.1 struct thermal_cooling_device *cpufreq_cooling_register(
> +       struct freq_clip_table *tab_ptr, unsigned int tab_size)
> +
> +    This interface function registers the cpufreq cooling device with the name
> +    "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
> +    cooling devices.
> +
> +    tab_ptr: The table containing the maximum value of frequency to be clipped
> +    for each cooling state.
> +       .freq_clip_max: Value of frequency to be clipped for each allowed
> +        cpus.
> +       .temp_level: Temperature level at which the frequency clamping will
> +       happen.
> +       .mask_val: cpumask of the allowed cpu's
> +    tab_size: the total number of cpufreq cooling states.
> +
> +1.1.2 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
> +
> +    This interface function unregisters the "thermal-cpufreq-%x" cooling device.
> +
> +    cdev: Cooling device pointer which has to be unregistered.
> +
> +
> +1.2 CPU cooling action notifier register/unregister interface
> +1.2.1 int cputherm_register_notifier(struct notifier_block *nb,
> +       unsigned int list)
> +
> +    This interface registers a driver with cpu cooling layer. The driver will
> +    be notified when any cpu cooling action is called.
> +
> +    nb: notifier function to register
> +    list: CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP
> +
> +1.2.2 int cputherm_unregister_notifier(struct notifier_block *nb,
> +       unsigned int list)
> +
> +    This interface registers a driver with cpu cooling layer. The driver will
> +    be notified when any cpu cooling action is called.
> +
> +    nb: notifier function to register
> +    list: CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP
> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
> index 514a691..d9c529f 100644
> --- a/drivers/thermal/Kconfig
> +++ b/drivers/thermal/Kconfig
> @@ -19,6 +19,17 @@ config THERMAL_HWMON
>        depends on HWMON=y || HWMON=THERMAL
>        default y
>
> +config CPU_THERMAL

Perhaps the name CPU_COOLING or CPUFREQ_COOLING would more accurately
describe this functionality?  I like the latter since now this
mechanism only supports cooling by using cpufreq.

> +       bool "generic cpu cooling support"

If we use CPUFREQ_COOLING, then perhaps this could say:

bool "cpu cooling through cpufreq frequency limiting"

> +       depends on THERMAL && CPU_FREQ
> +       help
> +         This implements the generic cpu cooling mechanism through frequency
> +         reduction, cpu hotplug and any other ways of reducing temperature. An
> +         ACPI version of this already exists(drivers/acpi/processor_thermal.c).
> +         This will be useful for platforms using the generic thermal interface
> +         and not the ACPI interface.
> +         If you want this support, you should say Y or M here.
> +

Currently, only the "frequency reduction" method exists so perhaps
it's best to remove mention of "cpu hotplug and any other ways of
reducing temperature"?  Here'as a version for cpufreq only:

config CPUFREQ_COOLING
	bool "cpu cooling through cpufreq frequency limiting"
	depends on THERMAL && CPU_FREQ
	help
	  This implements a generic cpu cooling mechanism through cpufreq
	  frequency limiting. An ACPI version of this already exists
	  (drivers/acpi/processor_thermal.c).  This will be useful for
	  platforms using the generic thermal interface and not the ACPI
	  interface.
	  If you want this support, you should say Y or M here.

>  config SPEAR_THERMAL
>        bool "SPEAr thermal sensor driver"
>        depends on THERMAL
> diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
> index a9fff0b..30c456c 100644
> --- a/drivers/thermal/Makefile
> +++ b/drivers/thermal/Makefile
> @@ -3,4 +3,5 @@
>  #
>
>  obj-$(CONFIG_THERMAL)          += thermal_sys.o
> -obj-$(CONFIG_SPEAR_THERMAL)            += spear_thermal.o
> \ No newline at end of file
> +obj-$(CONFIG_CPU_THERMAL)       += cpu_cooling.o
> +obj-$(CONFIG_SPEAR_THERMAL)            += spear_thermal.o
> diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
> new file mode 100644
> index 0000000..c40d9a0
> --- /dev/null
> +++ b/drivers/thermal/cpu_cooling.c
> @@ -0,0 +1,483 @@
> +/*
> + *  linux/drivers/thermal/cpu_cooling.c
> + *
> + *  Copyright (C) 2012 Samsung Electronics Co., Ltd(http://www.samsung.com)
> + *  Copyright (C) 2012  Amit Daniel <amit.kachhap@linaro.org>
> + *
> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> + *  This program is free software; you can redistribute it and/or modify
> + *  it under the terms of the GNU General Public License as published by
> + *  the Free Software Foundation; version 2 of the License.
> + *
> + *  This program is distributed in the hope that it will be useful, but
> + *  WITHOUT ANY WARRANTY; without even the implied warranty of
> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + *  General Public License for more details.
> + *
> + *  You should have received a copy of the GNU General Public License along
> + *  with this program; if not, write to the Free Software Foundation, Inc.,
> + *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
> + *
> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> + */
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/thermal.h>
> +#include <linux/platform_device.h>
> +#include <linux/cpufreq.h>
> +#include <linux/err.h>
> +#include <linux/slab.h>
> +#include <linux/cpu.h>
> +#include <linux/cpu_cooling.h>
> +
> +/**
> + * struct cpufreq_cooling_device
> + * @id: unique integer value corresponding to each cpufreq_cooling_device
> + *     registered.
> + * @cool_dev: thermal_cooling_device pointer to keep track of the the
> + *     egistered cooling device.
> + * @tab_ptr: freq_clip_table table containing the maximum value of frequency to
> + *     be set for different cooling state.
> + * @tab_size: integer value representing a count of the above table.
> + * @cpufreq_state: integer value representing the current state of cpufreq
> + *     cooling devices.
> + * @allowed_cpus: all the cpus involved for this cpufreq_cooling_device.
> + * @node: list_head to link all cpufreq_cooling_device together.
> + *
> + * This structure is required for keeping information of each
> + * cpufreq_cooling_device registered as a list whose head is represented by
> + * cooling_cpufreq_list. In order to prevent corruption of this list a
> + * mutex lock cooling_cpufreq_lock is used.
> + */
> +struct cpufreq_cooling_device {
> +       int id;
> +       struct thermal_cooling_device *cool_dev;
> +       struct freq_clip_table *tab_ptr;
> +       unsigned int tab_size;
> +       unsigned int cpufreq_state;
> +       struct cpumask allowed_cpus;
> +       struct list_head node;
> +};
> +static LIST_HEAD(cooling_cpufreq_list);
> +static DEFINE_MUTEX(cooling_cpufreq_lock);
> +static DEFINE_IDR(cpufreq_idr);
> +
> +/*per cpu variable to store the previous max frequency allowed*/
> +static DEFINE_PER_CPU(unsigned int, max_policy_freq);
> +
> +/*notify_table passes value to the CPUFREQ_ADJUST callback function.*/
> +#define NOTIFY_INVALID NULL
> +static struct freq_clip_table *notify_table;
> +
> +/*Head of the blocking notifier chain to inform about frequency clamping*/
> +static BLOCKING_NOTIFIER_HEAD(cputherm_state_notifier_list);
> +
> +/**
> + * get_idr - function to get a unique id.
> + * @idr: struct idr * handle used to create a id.
> + * @id: int * value generated by this function.
> + */
> +static int get_idr(struct idr *idr, int *id)
> +{
> +       int err;
> +again:
> +       if (unlikely(idr_pre_get(idr, GFP_KERNEL) == 0))
> +               return -ENOMEM;
> +
> +       mutex_lock(&cooling_cpufreq_lock);
> +       err = idr_get_new(idr, NULL, id);
> +       mutex_unlock(&cooling_cpufreq_lock);
> +
> +       if (unlikely(err == -EAGAIN))
> +               goto again;
> +       else if (unlikely(err))
> +               return err;
> +
> +       *id = *id & MAX_ID_MASK;
> +       return 0;
> +}
> +
> +/**
> + * release_idr - function to free the unique id.
> + * @idr: struct idr * handle used for creating the id.
> + * @id: int value representing the unique id.
> + */
> +static void release_idr(struct idr *idr, int id)
> +{
> +       mutex_lock(&cooling_cpufreq_lock);
> +       idr_remove(idr, id);
> +       mutex_unlock(&cooling_cpufreq_lock);
> +}
> +
> +/**
> + * cputherm_register_notifier - Register a notifier with cpu cooling interface.
> + * @nb:        struct notifier_block * with callback info.
> + * @list: integer value for which notification is needed. possible values are
> + *     CPUFREQ_COOLING_START and CPUFREQ_COOLING_STOP.
> + *
> + * This exported function registers a driver with cpu cooling layer. The driver
> + * will be notified when any cpu cooling action is called.
> + */
> +int cputherm_register_notifier(struct notifier_block *nb, unsigned int list)
> +{
> +       int ret = 0;
> +
> +       switch (list) {
> +       case CPUFREQ_COOLING_START:
> +       case CPUFREQ_COOLING_STOP:
> +               ret = blocking_notifier_chain_register(
> +                               &cputherm_state_notifier_list, nb);
> +               break;
> +       default:
> +               ret = -EINVAL;
> +       }
> +       return ret;
> +}
> +EXPORT_SYMBOL(cputherm_register_notifier);
> +
> +/**
> + * cputherm_unregister_notifier - Un-register a notifier.
> + * @nb:        struct notifier_block * with callback info.
> + * @list: integer value for which notification is needed. values possible are
> + *     CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP.
> + *
> + * This exported function un-registers a driver with cpu cooling layer.
> + */
> +int cputherm_unregister_notifier(struct notifier_block *nb, unsigned int list)
> +{
> +       int ret = 0;
> +
> +       switch (list) {
> +       case CPUFREQ_COOLING_START:
> +       case CPUFREQ_COOLING_STOP:
> +               ret = blocking_notifier_chain_unregister(
> +                               &cputherm_state_notifier_list, nb);
> +               break;
> +       default:
> +               ret = -EINVAL;
> +       }
> +       return ret;
> +}
> +EXPORT_SYMBOL(cputherm_unregister_notifier);
> +
> +/*Below codes defines functions to be used for cpufreq as cooling device*/
> +
> +/**
> + * is_cpufreq_valid - function to check if a cpu has frequency transition policy.
> + * @cpu: cpu for which check is needed.
> + */
> +static int is_cpufreq_valid(int cpu)
> +{
> +       struct cpufreq_policy policy;
> +       return !cpufreq_get_policy(&policy, cpu);
> +}
> +
> +/**
> + * cpufreq_apply_cooling - function to apply frequency clipping.
> + * @cpufreq_device: cpufreq_cooling_device pointer containing frequency
> + *     clipping data.
> + * @cooling_state: value of the cooling state.
> + */
> +static int cpufreq_apply_cooling(struct cpufreq_cooling_device *cpufreq_device,
> +                               unsigned long cooling_state)
> +{
> +       unsigned int event, cpuid, state;
> +       struct freq_clip_table *th_table, *table_ptr;
> +       const struct cpumask *maskPtr = &cpufreq_device->allowed_cpus;
> +       struct cpufreq_cooling_device *cpufreq_ptr;
> +
> +       if (cooling_state > cpufreq_device->tab_size)
> +               return -EINVAL;
> +
> +       /*Check if the old cooling action is same as new cooling action*/
> +       if (cpufreq_device->cpufreq_state == cooling_state)
> +               return 0;
> +
> +       /*pass cooling table info to the cpufreq_thermal_notifier callback*/
> +       notify_table = NOTIFY_INVALID;
> +
> +       if (cooling_state > 0) {
> +               th_table = &(cpufreq_device->tab_ptr[cooling_state - 1]);
> +               notify_table = th_table;
> +       }
> +
> +       /*check if any lower clip frequency active in other cpufreq_device's*/
> +       list_for_each_entry(cpufreq_ptr, &cooling_cpufreq_list, node) {
> +
> +               state = cpufreq_ptr->cpufreq_state;
> +               if (state == 0 || cpufreq_ptr == cpufreq_device)
> +                       continue;
> +
> +               if (!cpumask_equal(&cpufreq_ptr->allowed_cpus,
> +                               &cpufreq_device->allowed_cpus))
> +                       continue;
> +
> +               table_ptr = &(cpufreq_ptr->tab_ptr[state - 1]);
> +               if (notify_table == NULL ||
> +                               (table_ptr->freq_clip_max <
> +                               notify_table->freq_clip_max))
> +                       notify_table =  table_ptr;
> +       }
> +
> +       cpufreq_device->cpufreq_state = cooling_state;
> +
> +       if (notify_table != NOTIFY_INVALID) {
> +               event = CPUFREQ_COOLING_START;
> +               maskPtr = notify_table->mask_val;
> +       } else {
> +               event = CPUFREQ_COOLING_STOP;
> +       }
> +
> +       blocking_notifier_call_chain(&cputherm_state_notifier_list,
> +                                               event, notify_table);
> +
> +       for_each_cpu(cpuid, maskPtr) {
> +               if (is_cpufreq_valid(cpuid))
> +                       cpufreq_update_policy(cpuid);
> +       }
> +
> +       notify_table = NOTIFY_INVALID;
> +
> +       return 0;
> +}
> +
> +/**
> + * cpufreq_thermal_notifier - notifier callback for cpufreq policy change.
> + * @nb:        struct notifier_block * with callback info.
> + * @event: value showing cpufreq event for which this function invoked.
> + * @data: callback-specific data
> + */
> +static int cpufreq_thermal_notifier(struct notifier_block *nb,
> +                                       unsigned long event, void *data)
> +{
> +       struct cpufreq_policy *policy = data;
> +       unsigned long max_freq = 0;
> +
> +       if (event != CPUFREQ_ADJUST)
> +               return 0;
> +
> +       if (notify_table != NOTIFY_INVALID) {
> +               max_freq = notify_table->freq_clip_max;
> +
> +               if (!per_cpu(max_policy_freq, policy->cpu))
> +                       per_cpu(max_policy_freq, policy->cpu) = policy->max;
> +       } else {
> +               if (per_cpu(max_policy_freq, policy->cpu)) {
> +                       max_freq = per_cpu(max_policy_freq, policy->cpu);
> +                       per_cpu(max_policy_freq, policy->cpu) = 0;
> +               } else {
> +                       max_freq = policy->max;
> +               }
> +       }
> +
> +       /* Never exceed user_policy.max*/
> +       if (max_freq > policy->user_policy.max)
> +               max_freq = policy->user_policy.max;
> +
> +       if (policy->max != max_freq)
> +               cpufreq_verify_within_limits(policy, 0, max_freq);
> +
> +       return 0;
> +}
> +
> +/*
> + * cpufreq cooling device callback functions are defined below
> + */
> +
> +/**
> + * cpufreq_get_max_state - callback function to get the max cooling state.
> + * @cdev: thermal cooling device pointer.
> + * @state: fill this variable with the max cooling state.
> + */
> +static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
> +                                unsigned long *state)
> +{
> +       int ret = -EINVAL;
> +       struct cpufreq_cooling_device *cpufreq_device;
> +
> +       mutex_lock(&cooling_cpufreq_lock);
> +       list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node) {
> +               if (cpufreq_device && cpufreq_device->cool_dev == cdev) {
> +                       *state = cpufreq_device->tab_size;
> +                       ret = 0;
> +                       break;
> +               }
> +       }
> +       mutex_unlock(&cooling_cpufreq_lock);
> +       return ret;
> +}
> +
> +/**
> + * cpufreq_get_cur_state - callback function to get the current cooling state.
> + * @cdev: thermal cooling device pointer.
> + * @state: fill this variable with the current cooling state.
> + */
> +static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
> +                                unsigned long *state)
> +{
> +       int ret = -EINVAL;
> +       struct cpufreq_cooling_device *cpufreq_device;
> +
> +       mutex_lock(&cooling_cpufreq_lock);
> +       list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node) {
> +               if (cpufreq_device && cpufreq_device->cool_dev == cdev) {
> +                       *state = cpufreq_device->cpufreq_state;
> +                       ret = 0;
> +                       break;
> +               }
> +       }
> +       mutex_unlock(&cooling_cpufreq_lock);
> +       return ret;
> +}
> +
> +/**
> + * cpufreq_set_cur_state - callback function to set the current cooling state.
> + * @cdev: thermal cooling device pointer.
> + * @state: set this variable to the current cooling state.
> + */
> +static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
> +                                unsigned long state)
> +{
> +       int ret = -EINVAL;
> +       struct cpufreq_cooling_device *cpufreq_device;
> +
> +       mutex_lock(&cooling_cpufreq_lock);
> +       list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node) {
> +               if (cpufreq_device && cpufreq_device->cool_dev == cdev) {
> +                       ret = 0;
> +                       break;
> +               }
> +       }
> +       if (!ret)
> +               ret = cpufreq_apply_cooling(cpufreq_device, state);
> +
> +       mutex_unlock(&cooling_cpufreq_lock);
> +
> +       return ret;
> +}
> +
> +/*Bind cpufreq callbacks to thermal cooling device ops*/
> +static struct thermal_cooling_device_ops const cpufreq_cooling_ops = {
> +       .get_max_state = cpufreq_get_max_state,
> +       .get_cur_state = cpufreq_get_cur_state,
> +       .set_cur_state = cpufreq_set_cur_state,
> +};
> +
> +/*Notifier for cpufreq policy change*/
> +static struct notifier_block thermal_cpufreq_notifier_block = {
> +       .notifier_call = cpufreq_thermal_notifier,
> +};
> +
> +/**
> + * cpufreq_cooling_register - function to create cpufreq cooling device.
> + * @tab_ptr: table ptr containing the maximum value of frequency to be clipped
> + *     for each cooling state.
> + * @tab_size: count of entries in the above table.
> + *     happen.
> + */
> +struct thermal_cooling_device *cpufreq_cooling_register(
> +       struct freq_clip_table *tab_ptr, unsigned int tab_size)
> +{
> +       struct thermal_cooling_device *cool_dev;
> +       struct cpufreq_cooling_device *cpufreq_dev = NULL;
> +       struct freq_clip_table *clip_tab;
> +       unsigned int cpufreq_dev_count = 0;
> +       char dev_name[THERMAL_NAME_LENGTH];
> +       int ret = 0, id = 0, i;
> +
> +       if (tab_ptr == NULL || tab_size == 0)
> +               return ERR_PTR(-EINVAL);
> +
> +       list_for_each_entry(cpufreq_dev, &cooling_cpufreq_list, node)
> +               cpufreq_dev_count++;
> +
> +       cpufreq_dev = kzalloc(sizeof(struct cpufreq_cooling_device),
> +                       GFP_KERNEL);
> +       if (!cpufreq_dev)
> +               return ERR_PTR(-ENOMEM);
> +
> +       /*Verify that all the entries of freq_clip_table are present*/
> +       for (i = 0; i < tab_size; i++) {
> +               clip_tab = ((struct freq_clip_table *)&tab_ptr[i]);
> +               if (!clip_tab->freq_clip_max || !clip_tab->mask_val
> +                                       || !clip_tab->temp_level) {
> +                       kfree(cpufreq_dev);
> +                       return ERR_PTR(-EINVAL);
> +               }
> +               /*
> +                *Consolidate all the cpumask for all the individual entries
> +                *of the trip table. This is useful in resetting all the
> +                *clipped frequencies to the normal level for each cpufreq
> +                *cooling device.
> +                */
> +               cpumask_or(&cpufreq_dev->allowed_cpus,
> +                       &cpufreq_dev->allowed_cpus, clip_tab->mask_val);
> +       }
> +
> +       cpufreq_dev->tab_ptr = tab_ptr;
> +       cpufreq_dev->tab_size = tab_size;
> +
> +       ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
> +       if (ret) {
> +               kfree(cpufreq_dev);
> +               return ERR_PTR(-EINVAL);
> +       }
> +
> +       sprintf(dev_name, "thermal-cpufreq-%d", cpufreq_dev->id);
> +
> +       cool_dev = thermal_cooling_device_register(dev_name, cpufreq_dev,
> +                                               &cpufreq_cooling_ops);
> +       if (!cool_dev) {
> +               release_idr(&cpufreq_idr, cpufreq_dev->id);
> +               kfree(cpufreq_dev);
> +               return ERR_PTR(-EINVAL);
> +       }
> +       cpufreq_dev->id = id;
> +       cpufreq_dev->cool_dev = cool_dev;
> +       mutex_lock(&cooling_cpufreq_lock);
> +       list_add_tail(&cpufreq_dev->node, &cooling_cpufreq_list);
> +
> +       /*Register the notifier for first cpufreq cooling device*/
> +       if (cpufreq_dev_count == 0)
> +               cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
> +                                               CPUFREQ_POLICY_NOTIFIER);
> +
> +       mutex_unlock(&cooling_cpufreq_lock);
> +       return cool_dev;
> +}
> +EXPORT_SYMBOL(cpufreq_cooling_register);
> +
> +/**
> + * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
> + * @cdev: thermal cooling device pointer.
> + */
> +void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
> +{
> +       struct cpufreq_cooling_device *cpufreq_dev = NULL;
> +       unsigned int cpufreq_dev_count = 0;
> +
> +       mutex_lock(&cooling_cpufreq_lock);
> +       list_for_each_entry(cpufreq_dev, &cooling_cpufreq_list, node) {
> +               if (cpufreq_dev && cpufreq_dev->cool_dev == cdev)
> +                       break;
> +               cpufreq_dev_count++;
> +       }
> +
> +       if (!cpufreq_dev || cpufreq_dev->cool_dev != cdev) {
> +               mutex_unlock(&cooling_cpufreq_lock);
> +               return;
> +       }
> +
> +       list_del(&cpufreq_dev->node);
> +
> +       /*Unregister the notifier for the last cpufreq cooling device*/
> +       if (cpufreq_dev_count == 1) {
> +               cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
> +                                       CPUFREQ_POLICY_NOTIFIER);
> +       }
> +       mutex_unlock(&cooling_cpufreq_lock);
> +       thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
> +       release_idr(&cpufreq_idr, cpufreq_dev->id);
> +       kfree(cpufreq_dev);
> +}
> +EXPORT_SYMBOL(cpufreq_cooling_unregister);
> diff --git a/include/linux/cpu_cooling.h b/include/linux/cpu_cooling.h
> new file mode 100644
> index 0000000..ed6c096
> --- /dev/null
> +++ b/include/linux/cpu_cooling.h
> @@ -0,0 +1,99 @@
> +/*
> + *  linux/include/linux/cpu_cooling.h
> + *
> + *  Copyright (C) 2012 Samsung Electronics Co., Ltd(http://www.samsung.com)
> + *  Copyright (C) 2012  Amit Daniel <amit.kachhap@linaro.org>
> + *
> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> + *  This program is free software; you can redistribute it and/or modify
> + *  it under the terms of the GNU General Public License as published by
> + *  the Free Software Foundation; version 2 of the License.
> + *
> + *  This program is distributed in the hope that it will be useful, but
> + *  WITHOUT ANY WARRANTY; without even the implied warranty of
> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + *  General Public License for more details.
> + *
> + *  You should have received a copy of the GNU General Public License along
> + *  with this program; if not, write to the Free Software Foundation, Inc.,
> + *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
> + *
> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> + */
> +
> +#ifndef __CPU_COOLING_H__
> +#define __CPU_COOLING_H__
> +
> +#include <linux/thermal.h>
> +
> +#define CPUFREQ_COOLING_START          0
> +#define CPUFREQ_COOLING_STOP           1
> +
> +/**
> + * struct freq_clip_table
> + * @freq_clip_max: maximum frequency allowed for this cooling state.
> + * @temp_level: Temperature level at which the temperature clipping will
> + *     happen.
> + * @mask_val: cpumask of the allowed cpu's where the clipping will take place.
> + *
> + * This structure is required to be filled and passed to the
> + * cpufreq_cooling_unregister function.
> + */
> +struct freq_clip_table {
> +       unsigned int freq_clip_max;
> +       unsigned int temp_level;
> +       const struct cpumask *mask_val;
> +};
> +
> +/**
> + * cputherm_register_notifier - Register a notifier with cpu cooling interface.
> + * @nb:        struct notifier_block * with callback info.
> + * @list: integer value for which notification is needed. possible values are
> + *     CPUFREQ_COOLING_TYPE and CPUHOTPLUG_COOLING_TYPE.

CPUFREQ_COOLING_TYPE and CPUHOTPLUG_COOLING_TYPE should be changed to
CPUFREQ_COOLING_START CPUFREQ_COOLING_STOP, right?

> + *
> + * This exported function registers a driver with cpu cooling layer. The driver
> + * will be notified when any cpu cooling action is called.
> + */
> +int cputherm_register_notifier(struct notifier_block *nb, unsigned int list);
> +
> +/**
> + * cputherm_unregister_notifier - Un-register a notifier.
> + * @nb:        struct notifier_block * with callback info.
> + * @list: integer value for which notification is needed. values possible are
> + *     CPUFREQ_COOLING_TYPE.

Should be changed to CPUFREQ_COOLING_START, CPUFREQ_COOLING_STOP, right?

> + *
> + * This exported function un-registers a driver with cpu cooling layer.
> + */
> +int cputherm_unregister_notifier(struct notifier_block *nb, unsigned int list);
> +
> +#ifdef CONFIG_CPU_FREQ

Consider changing this to "#ifdef CPU_THERMAL"  A platform thermal
driver may want to always call this function as its cpu cooling
mechanism but it should still function without the cpu_cooling being
enabled.  In this case, the platform thermal driver would only provide
temperature readings and critical trip point handling.  But if the
platform happened may have CONFIG_CPU_FREQ enabled, a build error
would occur in the current implementation.

(the CONFIG_CPU_FREQ requirement will be met by CPU_THERMAL being
enabled since it also implies CONFIG_CPU_FREQ being enabled per the
Kconfig dependency)

> +/**
> + * cpufreq_cooling_register - function to create cpufreq cooling device.
> + * @tab_ptr: table ptr containing the maximum value of frequency to be clipped
> + *     for each cooling state.
> + * @tab_size: count of entries in the above table.
> + * @mask_val: cpumask containing the allowed cpu's where frequency clipping can
> + *     happen.
> + */
> +struct thermal_cooling_device *cpufreq_cooling_register(
> +       struct freq_clip_table *tab_ptr, unsigned int tab_size);
> +
> +/**
> + * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
> + * @cdev: thermal cooling device pointer.
> + */
> +void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev);
> +#else /*!CONFIG_CPU_FREQ*/

Modify comment if above suggestion is taken.

> +static inline struct thermal_cooling_device *cpufreq_cooling_register(
> +       struct freq_clip_table *tab_ptr, unsigned int tab_size);
> +{
> +       return NULL;
> +}
> +static inline void cpufreq_cooling_unregister(
> +               struct thermal_cooling_device *cdev)
> +{
> +       return;
> +}
> +#endif /*CONFIG_CPU_FREQ*/

Modify comment if above suggestion is taken.

> +
> +#endif /* __CPU_COOLING_H__ */
> --
> 1.7.1
>
>
> _______________________________________________
> linaro-dev mailing list
> linaro-dev@lists.linaro.org
> http://lists.linaro.org/mailman/listinfo/linaro-dev

Hey Rob and Amit,

On Tue, Jun 26, 2012 at 6:12 AM, Rob Lee <rob.lee@linaro.org> wrote:
> Hey Amit,
>
> I was just re-organizing the imx thermal driver that uses this cpu
> cooling interface and noticed a couple of small issues here.   If

While rewriting the OMAP BG driver on top of this series I noticed
similar issues. Apart from those pointed by Rob, I have another minor
fix.

> these suggestions are agreed upon and if it's too late for these
> issues be changed with this patchset, I can submit them separately
> unless you'd prefer to.
>
> On Sat, May 12, 2012 at 4:40 AM, Amit Daniel Kachhap
> <amit.kachhap@linaro.org> wrote:
>> This patch adds support for generic cpu thermal cooling low level
>> implementations using frequency scaling up/down based on the registration
>> parameters. Different cpu related cooling devices can be registered by the
>> user and the binding of these cooling devices to the corresponding
>> trip points can be easily done as the registration APIs return the
>> cooling device pointer. The user of these APIs are responsible for
>> passing clipping frequency . The drivers can also register to recieve
>> notification about any cooling action called.
>>
>> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@linaro.org>
>> ---
>>  Documentation/thermal/cpu-cooling-api.txt |   60 ++++
>>  drivers/thermal/Kconfig                   |   11 +
>>  drivers/thermal/Makefile                  |    3 +-
>>  drivers/thermal/cpu_cooling.c             |  483 +++++++++++++++++++++++++++++
>>  include/linux/cpu_cooling.h               |   99 ++++++
>>  5 files changed, 655 insertions(+), 1 deletions(-)
>>  create mode 100644 Documentation/thermal/cpu-cooling-api.txt
>>  create mode 100644 drivers/thermal/cpu_cooling.c
>>  create mode 100644 include/linux/cpu_cooling.h
>>
>> diff --git a/Documentation/thermal/cpu-cooling-api.txt b/Documentation/thermal/cpu-cooling-api.txt
>> new file mode 100644
>> index 0000000..557adb8
>> --- /dev/null
>> +++ b/Documentation/thermal/cpu-cooling-api.txt
>> @@ -0,0 +1,60 @@
>> +CPU cooling APIs How To
>> +===================================
>> +
>> +Written by Amit Daniel Kachhap <amit.kachhap@linaro.org>
>> +
>> +Updated: 12 May 2012
>> +
>> +Copyright (c)  2012 Samsung Electronics Co., Ltd(http://www.samsung.com)
>> +
>> +0. Introduction
>> +
>> +The generic cpu cooling(freq clipping, cpuhotplug etc) provides
>> +registration/unregistration APIs to the caller. The binding of the cooling
>> +devices to the trip point is left for the user. The registration APIs returns
>> +the cooling device pointer.
>> +
>> +1. cpu cooling APIs
>> +
>> +1.1 cpufreq registration/unregistration APIs
>> +1.1.1 struct thermal_cooling_device *cpufreq_cooling_register(
>> +       struct freq_clip_table *tab_ptr, unsigned int tab_size)
>> +
>> +    This interface function registers the cpufreq cooling device with the name
>> +    "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
>> +    cooling devices.
>> +
>> +    tab_ptr: The table containing the maximum value of frequency to be clipped
>> +    for each cooling state.
>> +       .freq_clip_max: Value of frequency to be clipped for each allowed
>> +        cpus.
>> +       .temp_level: Temperature level at which the frequency clamping will
>> +       happen.
>> +       .mask_val: cpumask of the allowed cpu's
>> +    tab_size: the total number of cpufreq cooling states.
>> +
>> +1.1.2 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
>> +
>> +    This interface function unregisters the "thermal-cpufreq-%x" cooling device.
>> +
>> +    cdev: Cooling device pointer which has to be unregistered.
>> +
>> +
>> +1.2 CPU cooling action notifier register/unregister interface
>> +1.2.1 int cputherm_register_notifier(struct notifier_block *nb,
>> +       unsigned int list)
>> +
>> +    This interface registers a driver with cpu cooling layer. The driver will
>> +    be notified when any cpu cooling action is called.
>> +
>> +    nb: notifier function to register
>> +    list: CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP
>> +
>> +1.2.2 int cputherm_unregister_notifier(struct notifier_block *nb,
>> +       unsigned int list)
>> +
>> +    This interface registers a driver with cpu cooling layer. The driver will
>> +    be notified when any cpu cooling action is called.
>> +
>> +    nb: notifier function to register
>> +    list: CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP
>> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
>> index 514a691..d9c529f 100644
>> --- a/drivers/thermal/Kconfig
>> +++ b/drivers/thermal/Kconfig
>> @@ -19,6 +19,17 @@ config THERMAL_HWMON
>>        depends on HWMON=y || HWMON=THERMAL
>>        default y
>>
>> +config CPU_THERMAL
>
> Perhaps the name CPU_COOLING or CPUFREQ_COOLING would more accurately
> describe this functionality?  I like the latter since now this
> mechanism only supports cooling by using cpufreq.
>
>> +       bool "generic cpu cooling support"
>
> If we use CPUFREQ_COOLING, then perhaps this could say:
>
> bool "cpu cooling through cpufreq frequency limiting"
>
>> +       depends on THERMAL && CPU_FREQ
>> +       help
>> +         This implements the generic cpu cooling mechanism through frequency
>> +         reduction, cpu hotplug and any other ways of reducing temperature. An
>> +         ACPI version of this already exists(drivers/acpi/processor_thermal.c).
>> +         This will be useful for platforms using the generic thermal interface
>> +         and not the ACPI interface.
>> +         If you want this support, you should say Y or M here.
>> +
>
> Currently, only the "frequency reduction" method exists so perhaps
> it's best to remove mention of "cpu hotplug and any other ways of
> reducing temperature"?  Here'as a version for cpufreq only:
>
> config CPUFREQ_COOLING
>        bool "cpu cooling through cpufreq frequency limiting"
>        depends on THERMAL && CPU_FREQ
>        help
>          This implements a generic cpu cooling mechanism through cpufreq
>          frequency limiting. An ACPI version of this already exists
>          (drivers/acpi/processor_thermal.c).  This will be useful for
>          platforms using the generic thermal interface and not the ACPI
>          interface.
>          If you want this support, you should say Y or M here.
>
>>  config SPEAR_THERMAL
>>        bool "SPEAr thermal sensor driver"
>>        depends on THERMAL
>> diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
>> index a9fff0b..30c456c 100644
>> --- a/drivers/thermal/Makefile
>> +++ b/drivers/thermal/Makefile
>> @@ -3,4 +3,5 @@
>>  #
>>
>>  obj-$(CONFIG_THERMAL)          += thermal_sys.o
>> -obj-$(CONFIG_SPEAR_THERMAL)            += spear_thermal.o
>> \ No newline at end of file
>> +obj-$(CONFIG_CPU_THERMAL)       += cpu_cooling.o
>> +obj-$(CONFIG_SPEAR_THERMAL)            += spear_thermal.o
>> diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
>> new file mode 100644
>> index 0000000..c40d9a0
>> --- /dev/null
>> +++ b/drivers/thermal/cpu_cooling.c
>> @@ -0,0 +1,483 @@
>> +/*
>> + *  linux/drivers/thermal/cpu_cooling.c
>> + *
>> + *  Copyright (C) 2012 Samsung Electronics Co., Ltd(http://www.samsung.com)
>> + *  Copyright (C) 2012  Amit Daniel <amit.kachhap@linaro.org>
>> + *
>> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> + *  This program is free software; you can redistribute it and/or modify
>> + *  it under the terms of the GNU General Public License as published by
>> + *  the Free Software Foundation; version 2 of the License.
>> + *
>> + *  This program is distributed in the hope that it will be useful, but
>> + *  WITHOUT ANY WARRANTY; without even the implied warranty of
>> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>> + *  General Public License for more details.
>> + *
>> + *  You should have received a copy of the GNU General Public License along
>> + *  with this program; if not, write to the Free Software Foundation, Inc.,
>> + *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
>> + *
>> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> + */
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/thermal.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/cpufreq.h>
>> +#include <linux/err.h>
>> +#include <linux/slab.h>
>> +#include <linux/cpu.h>
>> +#include <linux/cpu_cooling.h>
>> +
>> +/**
>> + * struct cpufreq_cooling_device
>> + * @id: unique integer value corresponding to each cpufreq_cooling_device
>> + *     registered.
>> + * @cool_dev: thermal_cooling_device pointer to keep track of the the
>> + *     egistered cooling device.
>> + * @tab_ptr: freq_clip_table table containing the maximum value of frequency to
>> + *     be set for different cooling state.
>> + * @tab_size: integer value representing a count of the above table.
>> + * @cpufreq_state: integer value representing the current state of cpufreq
>> + *     cooling devices.
>> + * @allowed_cpus: all the cpus involved for this cpufreq_cooling_device.
>> + * @node: list_head to link all cpufreq_cooling_device together.
>> + *
>> + * This structure is required for keeping information of each
>> + * cpufreq_cooling_device registered as a list whose head is represented by
>> + * cooling_cpufreq_list. In order to prevent corruption of this list a
>> + * mutex lock cooling_cpufreq_lock is used.
>> + */
>> +struct cpufreq_cooling_device {
>> +       int id;
>> +       struct thermal_cooling_device *cool_dev;
>> +       struct freq_clip_table *tab_ptr;
>> +       unsigned int tab_size;
>> +       unsigned int cpufreq_state;
>> +       struct cpumask allowed_cpus;
>> +       struct list_head node;
>> +};
>> +static LIST_HEAD(cooling_cpufreq_list);
>> +static DEFINE_MUTEX(cooling_cpufreq_lock);
>> +static DEFINE_IDR(cpufreq_idr);
>> +
>> +/*per cpu variable to store the previous max frequency allowed*/
>> +static DEFINE_PER_CPU(unsigned int, max_policy_freq);
>> +
>> +/*notify_table passes value to the CPUFREQ_ADJUST callback function.*/
>> +#define NOTIFY_INVALID NULL
>> +static struct freq_clip_table *notify_table;
>> +
>> +/*Head of the blocking notifier chain to inform about frequency clamping*/
>> +static BLOCKING_NOTIFIER_HEAD(cputherm_state_notifier_list);
>> +
>> +/**
>> + * get_idr - function to get a unique id.
>> + * @idr: struct idr * handle used to create a id.
>> + * @id: int * value generated by this function.
>> + */
>> +static int get_idr(struct idr *idr, int *id)
>> +{
>> +       int err;
>> +again:
>> +       if (unlikely(idr_pre_get(idr, GFP_KERNEL) == 0))
>> +               return -ENOMEM;
>> +
>> +       mutex_lock(&cooling_cpufreq_lock);
>> +       err = idr_get_new(idr, NULL, id);
>> +       mutex_unlock(&cooling_cpufreq_lock);
>> +
>> +       if (unlikely(err == -EAGAIN))
>> +               goto again;
>> +       else if (unlikely(err))
>> +               return err;
>> +
>> +       *id = *id & MAX_ID_MASK;
>> +       return 0;
>> +}
>> +
>> +/**
>> + * release_idr - function to free the unique id.
>> + * @idr: struct idr * handle used for creating the id.
>> + * @id: int value representing the unique id.
>> + */
>> +static void release_idr(struct idr *idr, int id)
>> +{
>> +       mutex_lock(&cooling_cpufreq_lock);
>> +       idr_remove(idr, id);
>> +       mutex_unlock(&cooling_cpufreq_lock);
>> +}
>> +
>> +/**
>> + * cputherm_register_notifier - Register a notifier with cpu cooling interface.
>> + * @nb:        struct notifier_block * with callback info.
>> + * @list: integer value for which notification is needed. possible values are
>> + *     CPUFREQ_COOLING_START and CPUFREQ_COOLING_STOP.
>> + *
>> + * This exported function registers a driver with cpu cooling layer. The driver
>> + * will be notified when any cpu cooling action is called.
>> + */
>> +int cputherm_register_notifier(struct notifier_block *nb, unsigned int list)
>> +{
>> +       int ret = 0;
>> +
>> +       switch (list) {
>> +       case CPUFREQ_COOLING_START:
>> +       case CPUFREQ_COOLING_STOP:
>> +               ret = blocking_notifier_chain_register(
>> +                               &cputherm_state_notifier_list, nb);
>> +               break;
>> +       default:
>> +               ret = -EINVAL;
>> +       }
>> +       return ret;
>> +}
>> +EXPORT_SYMBOL(cputherm_register_notifier);
>> +
>> +/**
>> + * cputherm_unregister_notifier - Un-register a notifier.
>> + * @nb:        struct notifier_block * with callback info.
>> + * @list: integer value for which notification is needed. values possible are
>> + *     CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP.
>> + *
>> + * This exported function un-registers a driver with cpu cooling layer.
>> + */
>> +int cputherm_unregister_notifier(struct notifier_block *nb, unsigned int list)
>> +{
>> +       int ret = 0;
>> +
>> +       switch (list) {
>> +       case CPUFREQ_COOLING_START:
>> +       case CPUFREQ_COOLING_STOP:
>> +               ret = blocking_notifier_chain_unregister(
>> +                               &cputherm_state_notifier_list, nb);
>> +               break;
>> +       default:
>> +               ret = -EINVAL;
>> +       }
>> +       return ret;
>> +}
>> +EXPORT_SYMBOL(cputherm_unregister_notifier);
>> +
>> +/*Below codes defines functions to be used for cpufreq as cooling device*/
>> +
>> +/**
>> + * is_cpufreq_valid - function to check if a cpu has frequency transition policy.
>> + * @cpu: cpu for which check is needed.
>> + */
>> +static int is_cpufreq_valid(int cpu)
>> +{
>> +       struct cpufreq_policy policy;
>> +       return !cpufreq_get_policy(&policy, cpu);
>> +}
>> +
>> +/**
>> + * cpufreq_apply_cooling - function to apply frequency clipping.
>> + * @cpufreq_device: cpufreq_cooling_device pointer containing frequency
>> + *     clipping data.
>> + * @cooling_state: value of the cooling state.
>> + */
>> +static int cpufreq_apply_cooling(struct cpufreq_cooling_device *cpufreq_device,
>> +                               unsigned long cooling_state)
>> +{
>> +       unsigned int event, cpuid, state;
>> +       struct freq_clip_table *th_table, *table_ptr;
>> +       const struct cpumask *maskPtr = &cpufreq_device->allowed_cpus;
>> +       struct cpufreq_cooling_device *cpufreq_ptr;
>> +
>> +       if (cooling_state > cpufreq_device->tab_size)
>> +               return -EINVAL;
>> +
>> +       /*Check if the old cooling action is same as new cooling action*/
>> +       if (cpufreq_device->cpufreq_state == cooling_state)
>> +               return 0;
>> +
>> +       /*pass cooling table info to the cpufreq_thermal_notifier callback*/
>> +       notify_table = NOTIFY_INVALID;
>> +
>> +       if (cooling_state > 0) {
>> +               th_table = &(cpufreq_device->tab_ptr[cooling_state - 1]);
>> +               notify_table = th_table;
>> +       }
>> +
>> +       /*check if any lower clip frequency active in other cpufreq_device's*/
>> +       list_for_each_entry(cpufreq_ptr, &cooling_cpufreq_list, node) {
>> +
>> +               state = cpufreq_ptr->cpufreq_state;
>> +               if (state == 0 || cpufreq_ptr == cpufreq_device)
>> +                       continue;
>> +
>> +               if (!cpumask_equal(&cpufreq_ptr->allowed_cpus,
>> +                               &cpufreq_device->allowed_cpus))
>> +                       continue;
>> +
>> +               table_ptr = &(cpufreq_ptr->tab_ptr[state - 1]);
>> +               if (notify_table == NULL ||
>> +                               (table_ptr->freq_clip_max <
>> +                               notify_table->freq_clip_max))
>> +                       notify_table =  table_ptr;
>> +       }
>> +
>> +       cpufreq_device->cpufreq_state = cooling_state;
>> +
>> +       if (notify_table != NOTIFY_INVALID) {
>> +               event = CPUFREQ_COOLING_START;
>> +               maskPtr = notify_table->mask_val;
>> +       } else {
>> +               event = CPUFREQ_COOLING_STOP;
>> +       }
>> +
>> +       blocking_notifier_call_chain(&cputherm_state_notifier_list,
>> +                                               event, notify_table);
>> +
>> +       for_each_cpu(cpuid, maskPtr) {
>> +               if (is_cpufreq_valid(cpuid))
>> +                       cpufreq_update_policy(cpuid);
>> +       }
>> +
>> +       notify_table = NOTIFY_INVALID;
>> +
>> +       return 0;
>> +}
>> +
>> +/**
>> + * cpufreq_thermal_notifier - notifier callback for cpufreq policy change.
>> + * @nb:        struct notifier_block * with callback info.
>> + * @event: value showing cpufreq event for which this function invoked.
>> + * @data: callback-specific data
>> + */
>> +static int cpufreq_thermal_notifier(struct notifier_block *nb,
>> +                                       unsigned long event, void *data)
>> +{
>> +       struct cpufreq_policy *policy = data;
>> +       unsigned long max_freq = 0;
>> +
>> +       if (event != CPUFREQ_ADJUST)
>> +               return 0;
>> +
>> +       if (notify_table != NOTIFY_INVALID) {
>> +               max_freq = notify_table->freq_clip_max;
>> +
>> +               if (!per_cpu(max_policy_freq, policy->cpu))
>> +                       per_cpu(max_policy_freq, policy->cpu) = policy->max;
>> +       } else {
>> +               if (per_cpu(max_policy_freq, policy->cpu)) {
>> +                       max_freq = per_cpu(max_policy_freq, policy->cpu);
>> +                       per_cpu(max_policy_freq, policy->cpu) = 0;
>> +               } else {
>> +                       max_freq = policy->max;
>> +               }
>> +       }
>> +
>> +       /* Never exceed user_policy.max*/
>> +       if (max_freq > policy->user_policy.max)
>> +               max_freq = policy->user_policy.max;
>> +
>> +       if (policy->max != max_freq)
>> +               cpufreq_verify_within_limits(policy, 0, max_freq);
>> +
>> +       return 0;
>> +}
>> +
>> +/*
>> + * cpufreq cooling device callback functions are defined below
>> + */
>> +
>> +/**
>> + * cpufreq_get_max_state - callback function to get the max cooling state.
>> + * @cdev: thermal cooling device pointer.
>> + * @state: fill this variable with the max cooling state.
>> + */
>> +static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
>> +                                unsigned long *state)
>> +{
>> +       int ret = -EINVAL;
>> +       struct cpufreq_cooling_device *cpufreq_device;
>> +
>> +       mutex_lock(&cooling_cpufreq_lock);
>> +       list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node) {
>> +               if (cpufreq_device && cpufreq_device->cool_dev == cdev) {
>> +                       *state = cpufreq_device->tab_size;
>> +                       ret = 0;
>> +                       break;
>> +               }
>> +       }
>> +       mutex_unlock(&cooling_cpufreq_lock);
>> +       return ret;
>> +}
>> +
>> +/**
>> + * cpufreq_get_cur_state - callback function to get the current cooling state.
>> + * @cdev: thermal cooling device pointer.
>> + * @state: fill this variable with the current cooling state.
>> + */
>> +static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
>> +                                unsigned long *state)
>> +{
>> +       int ret = -EINVAL;
>> +       struct cpufreq_cooling_device *cpufreq_device;
>> +
>> +       mutex_lock(&cooling_cpufreq_lock);
>> +       list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node) {
>> +               if (cpufreq_device && cpufreq_device->cool_dev == cdev) {
>> +                       *state = cpufreq_device->cpufreq_state;
>> +                       ret = 0;
>> +                       break;
>> +               }
>> +       }
>> +       mutex_unlock(&cooling_cpufreq_lock);
>> +       return ret;
>> +}
>> +
>> +/**
>> + * cpufreq_set_cur_state - callback function to set the current cooling state.
>> + * @cdev: thermal cooling device pointer.
>> + * @state: set this variable to the current cooling state.
>> + */
>> +static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
>> +                                unsigned long state)
>> +{
>> +       int ret = -EINVAL;
>> +       struct cpufreq_cooling_device *cpufreq_device;
>> +
>> +       mutex_lock(&cooling_cpufreq_lock);
>> +       list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node) {
>> +               if (cpufreq_device && cpufreq_device->cool_dev == cdev) {
>> +                       ret = 0;
>> +                       break;
>> +               }
>> +       }
>> +       if (!ret)
>> +               ret = cpufreq_apply_cooling(cpufreq_device, state);
>> +
>> +       mutex_unlock(&cooling_cpufreq_lock);
>> +
>> +       return ret;
>> +}
>> +
>> +/*Bind cpufreq callbacks to thermal cooling device ops*/
>> +static struct thermal_cooling_device_ops const cpufreq_cooling_ops = {
>> +       .get_max_state = cpufreq_get_max_state,
>> +       .get_cur_state = cpufreq_get_cur_state,
>> +       .set_cur_state = cpufreq_set_cur_state,
>> +};
>> +
>> +/*Notifier for cpufreq policy change*/
>> +static struct notifier_block thermal_cpufreq_notifier_block = {
>> +       .notifier_call = cpufreq_thermal_notifier,
>> +};
>> +
>> +/**
>> + * cpufreq_cooling_register - function to create cpufreq cooling device.
>> + * @tab_ptr: table ptr containing the maximum value of frequency to be clipped
>> + *     for each cooling state.
>> + * @tab_size: count of entries in the above table.
>> + *     happen.
>> + */
>> +struct thermal_cooling_device *cpufreq_cooling_register(
>> +       struct freq_clip_table *tab_ptr, unsigned int tab_size)
>> +{
>> +       struct thermal_cooling_device *cool_dev;
>> +       struct cpufreq_cooling_device *cpufreq_dev = NULL;
>> +       struct freq_clip_table *clip_tab;
>> +       unsigned int cpufreq_dev_count = 0;
>> +       char dev_name[THERMAL_NAME_LENGTH];
>> +       int ret = 0, id = 0, i;
>> +
>> +       if (tab_ptr == NULL || tab_size == 0)
>> +               return ERR_PTR(-EINVAL);
>> +
>> +       list_for_each_entry(cpufreq_dev, &cooling_cpufreq_list, node)
>> +               cpufreq_dev_count++;
>> +
>> +       cpufreq_dev = kzalloc(sizeof(struct cpufreq_cooling_device),
>> +                       GFP_KERNEL);
>> +       if (!cpufreq_dev)
>> +               return ERR_PTR(-ENOMEM);
>> +
>> +       /*Verify that all the entries of freq_clip_table are present*/
>> +       for (i = 0; i < tab_size; i++) {
>> +               clip_tab = ((struct freq_clip_table *)&tab_ptr[i]);
>> +               if (!clip_tab->freq_clip_max || !clip_tab->mask_val
>> +                                       || !clip_tab->temp_level) {
>> +                       kfree(cpufreq_dev);
>> +                       return ERR_PTR(-EINVAL);
>> +               }
>> +               /*
>> +                *Consolidate all the cpumask for all the individual entries
>> +                *of the trip table. This is useful in resetting all the
>> +                *clipped frequencies to the normal level for each cpufreq
>> +                *cooling device.
>> +                */
>> +               cpumask_or(&cpufreq_dev->allowed_cpus,
>> +                       &cpufreq_dev->allowed_cpus, clip_tab->mask_val);
>> +       }
>> +
>> +       cpufreq_dev->tab_ptr = tab_ptr;
>> +       cpufreq_dev->tab_size = tab_size;
>> +
>> +       ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
>> +       if (ret) {
>> +               kfree(cpufreq_dev);
>> +               return ERR_PTR(-EINVAL);
>> +       }
>> +
>> +       sprintf(dev_name, "thermal-cpufreq-%d", cpufreq_dev->id);
>> +
>> +       cool_dev = thermal_cooling_device_register(dev_name, cpufreq_dev,
>> +                                               &cpufreq_cooling_ops);
>> +       if (!cool_dev) {
>> +               release_idr(&cpufreq_idr, cpufreq_dev->id);
>> +               kfree(cpufreq_dev);
>> +               return ERR_PTR(-EINVAL);
>> +       }
>> +       cpufreq_dev->id = id;
>> +       cpufreq_dev->cool_dev = cool_dev;
>> +       mutex_lock(&cooling_cpufreq_lock);
>> +       list_add_tail(&cpufreq_dev->node, &cooling_cpufreq_list);
>> +
>> +       /*Register the notifier for first cpufreq cooling device*/
>> +       if (cpufreq_dev_count == 0)
>> +               cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
>> +                                               CPUFREQ_POLICY_NOTIFIER);
>> +
>> +       mutex_unlock(&cooling_cpufreq_lock);
>> +       return cool_dev;
>> +}
>> +EXPORT_SYMBOL(cpufreq_cooling_register);
>> +
>> +/**
>> + * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
>> + * @cdev: thermal cooling device pointer.
>> + */
>> +void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
>> +{
>> +       struct cpufreq_cooling_device *cpufreq_dev = NULL;
>> +       unsigned int cpufreq_dev_count = 0;
>> +
>> +       mutex_lock(&cooling_cpufreq_lock);
>> +       list_for_each_entry(cpufreq_dev, &cooling_cpufreq_list, node) {
>> +               if (cpufreq_dev && cpufreq_dev->cool_dev == cdev)
>> +                       break;
>> +               cpufreq_dev_count++;
>> +       }
>> +
>> +       if (!cpufreq_dev || cpufreq_dev->cool_dev != cdev) {
>> +               mutex_unlock(&cooling_cpufreq_lock);
>> +               return;
>> +       }
>> +
>> +       list_del(&cpufreq_dev->node);
>> +
>> +       /*Unregister the notifier for the last cpufreq cooling device*/
>> +       if (cpufreq_dev_count == 1) {
>> +               cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
>> +                                       CPUFREQ_POLICY_NOTIFIER);
>> +       }
>> +       mutex_unlock(&cooling_cpufreq_lock);
>> +       thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
>> +       release_idr(&cpufreq_idr, cpufreq_dev->id);
>> +       kfree(cpufreq_dev);
>> +}
>> +EXPORT_SYMBOL(cpufreq_cooling_unregister);
>> diff --git a/include/linux/cpu_cooling.h b/include/linux/cpu_cooling.h
>> new file mode 100644
>> index 0000000..ed6c096
>> --- /dev/null
>> +++ b/include/linux/cpu_cooling.h
>> @@ -0,0 +1,99 @@
>> +/*
>> + *  linux/include/linux/cpu_cooling.h
>> + *
>> + *  Copyright (C) 2012 Samsung Electronics Co., Ltd(http://www.samsung.com)
>> + *  Copyright (C) 2012  Amit Daniel <amit.kachhap@linaro.org>
>> + *
>> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> + *  This program is free software; you can redistribute it and/or modify
>> + *  it under the terms of the GNU General Public License as published by
>> + *  the Free Software Foundation; version 2 of the License.
>> + *
>> + *  This program is distributed in the hope that it will be useful, but
>> + *  WITHOUT ANY WARRANTY; without even the implied warranty of
>> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>> + *  General Public License for more details.
>> + *
>> + *  You should have received a copy of the GNU General Public License along
>> + *  with this program; if not, write to the Free Software Foundation, Inc.,
>> + *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
>> + *
>> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> + */
>> +
>> +#ifndef __CPU_COOLING_H__
>> +#define __CPU_COOLING_H__
>> +
>> +#include <linux/thermal.h>
>> +
>> +#define CPUFREQ_COOLING_START          0
>> +#define CPUFREQ_COOLING_STOP           1
>> +
>> +/**
>> + * struct freq_clip_table
>> + * @freq_clip_max: maximum frequency allowed for this cooling state.
>> + * @temp_level: Temperature level at which the temperature clipping will
>> + *     happen.
>> + * @mask_val: cpumask of the allowed cpu's where the clipping will take place.
>> + *
>> + * This structure is required to be filled and passed to the
>> + * cpufreq_cooling_unregister function.
>> + */
>> +struct freq_clip_table {
>> +       unsigned int freq_clip_max;
>> +       unsigned int temp_level;
>> +       const struct cpumask *mask_val;
>> +};
>> +
>> +/**
>> + * cputherm_register_notifier - Register a notifier with cpu cooling interface.
>> + * @nb:        struct notifier_block * with callback info.
>> + * @list: integer value for which notification is needed. possible values are
>> + *     CPUFREQ_COOLING_TYPE and CPUHOTPLUG_COOLING_TYPE.
>
> CPUFREQ_COOLING_TYPE and CPUHOTPLUG_COOLING_TYPE should be changed to
> CPUFREQ_COOLING_START CPUFREQ_COOLING_STOP, right?
>
>> + *
>> + * This exported function registers a driver with cpu cooling layer. The driver
>> + * will be notified when any cpu cooling action is called.
>> + */
>> +int cputherm_register_notifier(struct notifier_block *nb, unsigned int list);
>> +
>> +/**
>> + * cputherm_unregister_notifier - Un-register a notifier.
>> + * @nb:        struct notifier_block * with callback info.
>> + * @list: integer value for which notification is needed. values possible are
>> + *     CPUFREQ_COOLING_TYPE.
>
> Should be changed to CPUFREQ_COOLING_START, CPUFREQ_COOLING_STOP, right?
>
>> + *
>> + * This exported function un-registers a driver with cpu cooling layer.
>> + */
>> +int cputherm_unregister_notifier(struct notifier_block *nb, unsigned int list);
>> +
>> +#ifdef CONFIG_CPU_FREQ
>
> Consider changing this to "#ifdef CPU_THERMAL"  A platform thermal
> driver may want to always call this function as its cpu cooling
> mechanism but it should still function without the cpu_cooling being
> enabled.  In this case, the platform thermal driver would only provide
> temperature readings and critical trip point handling.  But if the
> platform happened may have CONFIG_CPU_FREQ enabled, a build error
> would occur in the current implementation.

I agree here. It makes more sense to have the check against CPU_THERMAL

>
> (the CONFIG_CPU_FREQ requirement will be met by CPU_THERMAL being
> enabled since it also implies CONFIG_CPU_FREQ being enabled per the
> Kconfig dependency)

True.

>
>> +/**
>> + * cpufreq_cooling_register - function to create cpufreq cooling device.
>> + * @tab_ptr: table ptr containing the maximum value of frequency to be clipped
>> + *     for each cooling state.
>> + * @tab_size: count of entries in the above table.
>> + * @mask_val: cpumask containing the allowed cpu's where frequency clipping can
>> + *     happen.
>> + */
>> +struct thermal_cooling_device *cpufreq_cooling_register(
>> +       struct freq_clip_table *tab_ptr, unsigned int tab_size);
>> +
>> +/**
>> + * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
>> + * @cdev: thermal cooling device pointer.
>> + */
>> +void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev);
>> +#else /*!CONFIG_CPU_FREQ*/
>
> Modify comment if above suggestion is taken.
>
>> +static inline struct thermal_cooling_device *cpufreq_cooling_register(
>> +       struct freq_clip_table *tab_ptr, unsigned int tab_size);

The above semicollon will cause a build error in case this path of the
ifdef is taken.

>> +{
>> +       return NULL;
>> +}
>> +static inline void cpufreq_cooling_unregister(
>> +               struct thermal_cooling_device *cdev)
>> +{
>> +       return;
>> +}
>> +#endif /*CONFIG_CPU_FREQ*/
>
> Modify comment if above suggestion is taken.
>
>> +
>> +#endif /* __CPU_COOLING_H__ */
>> --
>> 1.7.1
>>
>>
>> _______________________________________________
>> linaro-dev mailing list
>> linaro-dev@lists.linaro.org
>> http://lists.linaro.org/mailman/listinfo/linaro-dev
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Hi Rob/Eduardo,

As these patches have still not made into mainline. I will rebase the
whole set along with your suggestion and send them shortly.
Sorry for late reply.

Thanks,
Amit Daniel

On Tue, Jun 26, 2012 at 1:12 PM, Valentin, Eduardo
<eduardo.valentin@ti.com> wrote:
> Hey Rob and Amit,
>
> On Tue, Jun 26, 2012 at 6:12 AM, Rob Lee <rob.lee@linaro.org> wrote:
>> Hey Amit,
>>
>> I was just re-organizing the imx thermal driver that uses this cpu
>> cooling interface and noticed a couple of small issues here.   If
>
> While rewriting the OMAP BG driver on top of this series I noticed
> similar issues. Apart from those pointed by Rob, I have another minor
> fix.
>
>> these suggestions are agreed upon and if it's too late for these
>> issues be changed with this patchset, I can submit them separately
>> unless you'd prefer to.
>>
>> On Sat, May 12, 2012 at 4:40 AM, Amit Daniel Kachhap
>> <amit.kachhap@linaro.org> wrote:
>>> This patch adds support for generic cpu thermal cooling low level
>>> implementations using frequency scaling up/down based on the registration
>>> parameters. Different cpu related cooling devices can be registered by the
>>> user and the binding of these cooling devices to the corresponding
>>> trip points can be easily done as the registration APIs return the
>>> cooling device pointer. The user of these APIs are responsible for
>>> passing clipping frequency . The drivers can also register to recieve
>>> notification about any cooling action called.
>>>
>>> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@linaro.org>
>>> ---
>>>  Documentation/thermal/cpu-cooling-api.txt |   60 ++++
>>>  drivers/thermal/Kconfig                   |   11 +
>>>  drivers/thermal/Makefile                  |    3 +-
>>>  drivers/thermal/cpu_cooling.c             |  483 +++++++++++++++++++++++++++++
>>>  include/linux/cpu_cooling.h               |   99 ++++++
>>>  5 files changed, 655 insertions(+), 1 deletions(-)
>>>  create mode 100644 Documentation/thermal/cpu-cooling-api.txt
>>>  create mode 100644 drivers/thermal/cpu_cooling.c
>>>  create mode 100644 include/linux/cpu_cooling.h
>>>
>>> diff --git a/Documentation/thermal/cpu-cooling-api.txt b/Documentation/thermal/cpu-cooling-api.txt
>>> new file mode 100644
>>> index 0000000..557adb8
>>> --- /dev/null
>>> +++ b/Documentation/thermal/cpu-cooling-api.txt
>>> @@ -0,0 +1,60 @@
>>> +CPU cooling APIs How To
>>> +===================================
>>> +
>>> +Written by Amit Daniel Kachhap <amit.kachhap@linaro.org>
>>> +
>>> +Updated: 12 May 2012
>>> +
>>> +Copyright (c)  2012 Samsung Electronics Co., Ltd(http://www.samsung.com)
>>> +
>>> +0. Introduction
>>> +
>>> +The generic cpu cooling(freq clipping, cpuhotplug etc) provides
>>> +registration/unregistration APIs to the caller. The binding of the cooling
>>> +devices to the trip point is left for the user. The registration APIs returns
>>> +the cooling device pointer.
>>> +
>>> +1. cpu cooling APIs
>>> +
>>> +1.1 cpufreq registration/unregistration APIs
>>> +1.1.1 struct thermal_cooling_device *cpufreq_cooling_register(
>>> +       struct freq_clip_table *tab_ptr, unsigned int tab_size)
>>> +
>>> +    This interface function registers the cpufreq cooling device with the name
>>> +    "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
>>> +    cooling devices.
>>> +
>>> +    tab_ptr: The table containing the maximum value of frequency to be clipped
>>> +    for each cooling state.
>>> +       .freq_clip_max: Value of frequency to be clipped for each allowed
>>> +        cpus.
>>> +       .temp_level: Temperature level at which the frequency clamping will
>>> +       happen.
>>> +       .mask_val: cpumask of the allowed cpu's
>>> +    tab_size: the total number of cpufreq cooling states.
>>> +
>>> +1.1.2 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
>>> +
>>> +    This interface function unregisters the "thermal-cpufreq-%x" cooling device.
>>> +
>>> +    cdev: Cooling device pointer which has to be unregistered.
>>> +
>>> +
>>> +1.2 CPU cooling action notifier register/unregister interface
>>> +1.2.1 int cputherm_register_notifier(struct notifier_block *nb,
>>> +       unsigned int list)
>>> +
>>> +    This interface registers a driver with cpu cooling layer. The driver will
>>> +    be notified when any cpu cooling action is called.
>>> +
>>> +    nb: notifier function to register
>>> +    list: CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP
>>> +
>>> +1.2.2 int cputherm_unregister_notifier(struct notifier_block *nb,
>>> +       unsigned int list)
>>> +
>>> +    This interface registers a driver with cpu cooling layer. The driver will
>>> +    be notified when any cpu cooling action is called.
>>> +
>>> +    nb: notifier function to register
>>> +    list: CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP
>>> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
>>> index 514a691..d9c529f 100644
>>> --- a/drivers/thermal/Kconfig
>>> +++ b/drivers/thermal/Kconfig
>>> @@ -19,6 +19,17 @@ config THERMAL_HWMON
>>>        depends on HWMON=y || HWMON=THERMAL
>>>        default y
>>>
>>> +config CPU_THERMAL
>>
>> Perhaps the name CPU_COOLING or CPUFREQ_COOLING would more accurately
>> describe this functionality?  I like the latter since now this
>> mechanism only supports cooling by using cpufreq.
>>
>>> +       bool "generic cpu cooling support"
>>
>> If we use CPUFREQ_COOLING, then perhaps this could say:
>>
>> bool "cpu cooling through cpufreq frequency limiting"
>>
>>> +       depends on THERMAL && CPU_FREQ
>>> +       help
>>> +         This implements the generic cpu cooling mechanism through frequency
>>> +         reduction, cpu hotplug and any other ways of reducing temperature. An
>>> +         ACPI version of this already exists(drivers/acpi/processor_thermal.c).
>>> +         This will be useful for platforms using the generic thermal interface
>>> +         and not the ACPI interface.
>>> +         If you want this support, you should say Y or M here.
>>> +
>>
>> Currently, only the "frequency reduction" method exists so perhaps
>> it's best to remove mention of "cpu hotplug and any other ways of
>> reducing temperature"?  Here'as a version for cpufreq only:
>>
>> config CPUFREQ_COOLING
>>        bool "cpu cooling through cpufreq frequency limiting"
>>        depends on THERMAL && CPU_FREQ
>>        help
>>          This implements a generic cpu cooling mechanism through cpufreq
>>          frequency limiting. An ACPI version of this already exists
>>          (drivers/acpi/processor_thermal.c).  This will be useful for
>>          platforms using the generic thermal interface and not the ACPI
>>          interface.
>>          If you want this support, you should say Y or M here.
>>
>>>  config SPEAR_THERMAL
>>>        bool "SPEAr thermal sensor driver"
>>>        depends on THERMAL
>>> diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
>>> index a9fff0b..30c456c 100644
>>> --- a/drivers/thermal/Makefile
>>> +++ b/drivers/thermal/Makefile
>>> @@ -3,4 +3,5 @@
>>>  #
>>>
>>>  obj-$(CONFIG_THERMAL)          += thermal_sys.o
>>> -obj-$(CONFIG_SPEAR_THERMAL)            += spear_thermal.o
>>> \ No newline at end of file
>>> +obj-$(CONFIG_CPU_THERMAL)       += cpu_cooling.o
>>> +obj-$(CONFIG_SPEAR_THERMAL)            += spear_thermal.o
>>> diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
>>> new file mode 100644
>>> index 0000000..c40d9a0
>>> --- /dev/null
>>> +++ b/drivers/thermal/cpu_cooling.c
>>> @@ -0,0 +1,483 @@
>>> +/*
>>> + *  linux/drivers/thermal/cpu_cooling.c
>>> + *
>>> + *  Copyright (C) 2012 Samsung Electronics Co., Ltd(http://www.samsung.com)
>>> + *  Copyright (C) 2012  Amit Daniel <amit.kachhap@linaro.org>
>>> + *
>>> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>> + *  This program is free software; you can redistribute it and/or modify
>>> + *  it under the terms of the GNU General Public License as published by
>>> + *  the Free Software Foundation; version 2 of the License.
>>> + *
>>> + *  This program is distributed in the hope that it will be useful, but
>>> + *  WITHOUT ANY WARRANTY; without even the implied warranty of
>>> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>>> + *  General Public License for more details.
>>> + *
>>> + *  You should have received a copy of the GNU General Public License along
>>> + *  with this program; if not, write to the Free Software Foundation, Inc.,
>>> + *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
>>> + *
>>> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>> + */
>>> +#include <linux/kernel.h>
>>> +#include <linux/module.h>
>>> +#include <linux/thermal.h>
>>> +#include <linux/platform_device.h>
>>> +#include <linux/cpufreq.h>
>>> +#include <linux/err.h>
>>> +#include <linux/slab.h>
>>> +#include <linux/cpu.h>
>>> +#include <linux/cpu_cooling.h>
>>> +
>>> +/**
>>> + * struct cpufreq_cooling_device
>>> + * @id: unique integer value corresponding to each cpufreq_cooling_device
>>> + *     registered.
>>> + * @cool_dev: thermal_cooling_device pointer to keep track of the the
>>> + *     egistered cooling device.
>>> + * @tab_ptr: freq_clip_table table containing the maximum value of frequency to
>>> + *     be set for different cooling state.
>>> + * @tab_size: integer value representing a count of the above table.
>>> + * @cpufreq_state: integer value representing the current state of cpufreq
>>> + *     cooling devices.
>>> + * @allowed_cpus: all the cpus involved for this cpufreq_cooling_device.
>>> + * @node: list_head to link all cpufreq_cooling_device together.
>>> + *
>>> + * This structure is required for keeping information of each
>>> + * cpufreq_cooling_device registered as a list whose head is represented by
>>> + * cooling_cpufreq_list. In order to prevent corruption of this list a
>>> + * mutex lock cooling_cpufreq_lock is used.
>>> + */
>>> +struct cpufreq_cooling_device {
>>> +       int id;
>>> +       struct thermal_cooling_device *cool_dev;
>>> +       struct freq_clip_table *tab_ptr;
>>> +       unsigned int tab_size;
>>> +       unsigned int cpufreq_state;
>>> +       struct cpumask allowed_cpus;
>>> +       struct list_head node;
>>> +};
>>> +static LIST_HEAD(cooling_cpufreq_list);
>>> +static DEFINE_MUTEX(cooling_cpufreq_lock);
>>> +static DEFINE_IDR(cpufreq_idr);
>>> +
>>> +/*per cpu variable to store the previous max frequency allowed*/
>>> +static DEFINE_PER_CPU(unsigned int, max_policy_freq);
>>> +
>>> +/*notify_table passes value to the CPUFREQ_ADJUST callback function.*/
>>> +#define NOTIFY_INVALID NULL
>>> +static struct freq_clip_table *notify_table;
>>> +
>>> +/*Head of the blocking notifier chain to inform about frequency clamping*/
>>> +static BLOCKING_NOTIFIER_HEAD(cputherm_state_notifier_list);
>>> +
>>> +/**
>>> + * get_idr - function to get a unique id.
>>> + * @idr: struct idr * handle used to create a id.
>>> + * @id: int * value generated by this function.
>>> + */
>>> +static int get_idr(struct idr *idr, int *id)
>>> +{
>>> +       int err;
>>> +again:
>>> +       if (unlikely(idr_pre_get(idr, GFP_KERNEL) == 0))
>>> +               return -ENOMEM;
>>> +
>>> +       mutex_lock(&cooling_cpufreq_lock);
>>> +       err = idr_get_new(idr, NULL, id);
>>> +       mutex_unlock(&cooling_cpufreq_lock);
>>> +
>>> +       if (unlikely(err == -EAGAIN))
>>> +               goto again;
>>> +       else if (unlikely(err))
>>> +               return err;
>>> +
>>> +       *id = *id & MAX_ID_MASK;
>>> +       return 0;
>>> +}
>>> +
>>> +/**
>>> + * release_idr - function to free the unique id.
>>> + * @idr: struct idr * handle used for creating the id.
>>> + * @id: int value representing the unique id.
>>> + */
>>> +static void release_idr(struct idr *idr, int id)
>>> +{
>>> +       mutex_lock(&cooling_cpufreq_lock);
>>> +       idr_remove(idr, id);
>>> +       mutex_unlock(&cooling_cpufreq_lock);
>>> +}
>>> +
>>> +/**
>>> + * cputherm_register_notifier - Register a notifier with cpu cooling interface.
>>> + * @nb:        struct notifier_block * with callback info.
>>> + * @list: integer value for which notification is needed. possible values are
>>> + *     CPUFREQ_COOLING_START and CPUFREQ_COOLING_STOP.
>>> + *
>>> + * This exported function registers a driver with cpu cooling layer. The driver
>>> + * will be notified when any cpu cooling action is called.
>>> + */
>>> +int cputherm_register_notifier(struct notifier_block *nb, unsigned int list)
>>> +{
>>> +       int ret = 0;
>>> +
>>> +       switch (list) {
>>> +       case CPUFREQ_COOLING_START:
>>> +       case CPUFREQ_COOLING_STOP:
>>> +               ret = blocking_notifier_chain_register(
>>> +                               &cputherm_state_notifier_list, nb);
>>> +               break;
>>> +       default:
>>> +               ret = -EINVAL;
>>> +       }
>>> +       return ret;
>>> +}
>>> +EXPORT_SYMBOL(cputherm_register_notifier);
>>> +
>>> +/**
>>> + * cputherm_unregister_notifier - Un-register a notifier.
>>> + * @nb:        struct notifier_block * with callback info.
>>> + * @list: integer value for which notification is needed. values possible are
>>> + *     CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP.
>>> + *
>>> + * This exported function un-registers a driver with cpu cooling layer.
>>> + */
>>> +int cputherm_unregister_notifier(struct notifier_block *nb, unsigned int list)
>>> +{
>>> +       int ret = 0;
>>> +
>>> +       switch (list) {
>>> +       case CPUFREQ_COOLING_START:
>>> +       case CPUFREQ_COOLING_STOP:
>>> +               ret = blocking_notifier_chain_unregister(
>>> +                               &cputherm_state_notifier_list, nb);
>>> +               break;
>>> +       default:
>>> +               ret = -EINVAL;
>>> +       }
>>> +       return ret;
>>> +}
>>> +EXPORT_SYMBOL(cputherm_unregister_notifier);
>>> +
>>> +/*Below codes defines functions to be used for cpufreq as cooling device*/
>>> +
>>> +/**
>>> + * is_cpufreq_valid - function to check if a cpu has frequency transition policy.
>>> + * @cpu: cpu for which check is needed.
>>> + */
>>> +static int is_cpufreq_valid(int cpu)
>>> +{
>>> +       struct cpufreq_policy policy;
>>> +       return !cpufreq_get_policy(&policy, cpu);
>>> +}
>>> +
>>> +/**
>>> + * cpufreq_apply_cooling - function to apply frequency clipping.
>>> + * @cpufreq_device: cpufreq_cooling_device pointer containing frequency
>>> + *     clipping data.
>>> + * @cooling_state: value of the cooling state.
>>> + */
>>> +static int cpufreq_apply_cooling(struct cpufreq_cooling_device *cpufreq_device,
>>> +                               unsigned long cooling_state)
>>> +{
>>> +       unsigned int event, cpuid, state;
>>> +       struct freq_clip_table *th_table, *table_ptr;
>>> +       const struct cpumask *maskPtr = &cpufreq_device->allowed_cpus;
>>> +       struct cpufreq_cooling_device *cpufreq_ptr;
>>> +
>>> +       if (cooling_state > cpufreq_device->tab_size)
>>> +               return -EINVAL;
>>> +
>>> +       /*Check if the old cooling action is same as new cooling action*/
>>> +       if (cpufreq_device->cpufreq_state == cooling_state)
>>> +               return 0;
>>> +
>>> +       /*pass cooling table info to the cpufreq_thermal_notifier callback*/
>>> +       notify_table = NOTIFY_INVALID;
>>> +
>>> +       if (cooling_state > 0) {
>>> +               th_table = &(cpufreq_device->tab_ptr[cooling_state - 1]);
>>> +               notify_table = th_table;
>>> +       }
>>> +
>>> +       /*check if any lower clip frequency active in other cpufreq_device's*/
>>> +       list_for_each_entry(cpufreq_ptr, &cooling_cpufreq_list, node) {
>>> +
>>> +               state = cpufreq_ptr->cpufreq_state;
>>> +               if (state == 0 || cpufreq_ptr == cpufreq_device)
>>> +                       continue;
>>> +
>>> +               if (!cpumask_equal(&cpufreq_ptr->allowed_cpus,
>>> +                               &cpufreq_device->allowed_cpus))
>>> +                       continue;
>>> +
>>> +               table_ptr = &(cpufreq_ptr->tab_ptr[state - 1]);
>>> +               if (notify_table == NULL ||
>>> +                               (table_ptr->freq_clip_max <
>>> +                               notify_table->freq_clip_max))
>>> +                       notify_table =  table_ptr;
>>> +       }
>>> +
>>> +       cpufreq_device->cpufreq_state = cooling_state;
>>> +
>>> +       if (notify_table != NOTIFY_INVALID) {
>>> +               event = CPUFREQ_COOLING_START;
>>> +               maskPtr = notify_table->mask_val;
>>> +       } else {
>>> +               event = CPUFREQ_COOLING_STOP;
>>> +       }
>>> +
>>> +       blocking_notifier_call_chain(&cputherm_state_notifier_list,
>>> +                                               event, notify_table);
>>> +
>>> +       for_each_cpu(cpuid, maskPtr) {
>>> +               if (is_cpufreq_valid(cpuid))
>>> +                       cpufreq_update_policy(cpuid);
>>> +       }
>>> +
>>> +       notify_table = NOTIFY_INVALID;
>>> +
>>> +       return 0;
>>> +}
>>> +
>>> +/**
>>> + * cpufreq_thermal_notifier - notifier callback for cpufreq policy change.
>>> + * @nb:        struct notifier_block * with callback info.
>>> + * @event: value showing cpufreq event for which this function invoked.
>>> + * @data: callback-specific data
>>> + */
>>> +static int cpufreq_thermal_notifier(struct notifier_block *nb,
>>> +                                       unsigned long event, void *data)
>>> +{
>>> +       struct cpufreq_policy *policy = data;
>>> +       unsigned long max_freq = 0;
>>> +
>>> +       if (event != CPUFREQ_ADJUST)
>>> +               return 0;
>>> +
>>> +       if (notify_table != NOTIFY_INVALID) {
>>> +               max_freq = notify_table->freq_clip_max;
>>> +
>>> +               if (!per_cpu(max_policy_freq, policy->cpu))
>>> +                       per_cpu(max_policy_freq, policy->cpu) = policy->max;
>>> +       } else {
>>> +               if (per_cpu(max_policy_freq, policy->cpu)) {
>>> +                       max_freq = per_cpu(max_policy_freq, policy->cpu);
>>> +                       per_cpu(max_policy_freq, policy->cpu) = 0;
>>> +               } else {
>>> +                       max_freq = policy->max;
>>> +               }
>>> +       }
>>> +
>>> +       /* Never exceed user_policy.max*/
>>> +       if (max_freq > policy->user_policy.max)
>>> +               max_freq = policy->user_policy.max;
>>> +
>>> +       if (policy->max != max_freq)
>>> +               cpufreq_verify_within_limits(policy, 0, max_freq);
>>> +
>>> +       return 0;
>>> +}
>>> +
>>> +/*
>>> + * cpufreq cooling device callback functions are defined below
>>> + */
>>> +
>>> +/**
>>> + * cpufreq_get_max_state - callback function to get the max cooling state.
>>> + * @cdev: thermal cooling device pointer.
>>> + * @state: fill this variable with the max cooling state.
>>> + */
>>> +static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
>>> +                                unsigned long *state)
>>> +{
>>> +       int ret = -EINVAL;
>>> +       struct cpufreq_cooling_device *cpufreq_device;
>>> +
>>> +       mutex_lock(&cooling_cpufreq_lock);
>>> +       list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node) {
>>> +               if (cpufreq_device && cpufreq_device->cool_dev == cdev) {
>>> +                       *state = cpufreq_device->tab_size;
>>> +                       ret = 0;
>>> +                       break;
>>> +               }
>>> +       }
>>> +       mutex_unlock(&cooling_cpufreq_lock);
>>> +       return ret;
>>> +}
>>> +
>>> +/**
>>> + * cpufreq_get_cur_state - callback function to get the current cooling state.
>>> + * @cdev: thermal cooling device pointer.
>>> + * @state: fill this variable with the current cooling state.
>>> + */
>>> +static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
>>> +                                unsigned long *state)
>>> +{
>>> +       int ret = -EINVAL;
>>> +       struct cpufreq_cooling_device *cpufreq_device;
>>> +
>>> +       mutex_lock(&cooling_cpufreq_lock);
>>> +       list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node) {
>>> +               if (cpufreq_device && cpufreq_device->cool_dev == cdev) {
>>> +                       *state = cpufreq_device->cpufreq_state;
>>> +                       ret = 0;
>>> +                       break;
>>> +               }
>>> +       }
>>> +       mutex_unlock(&cooling_cpufreq_lock);
>>> +       return ret;
>>> +}
>>> +
>>> +/**
>>> + * cpufreq_set_cur_state - callback function to set the current cooling state.
>>> + * @cdev: thermal cooling device pointer.
>>> + * @state: set this variable to the current cooling state.
>>> + */
>>> +static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
>>> +                                unsigned long state)
>>> +{
>>> +       int ret = -EINVAL;
>>> +       struct cpufreq_cooling_device *cpufreq_device;
>>> +
>>> +       mutex_lock(&cooling_cpufreq_lock);
>>> +       list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node) {
>>> +               if (cpufreq_device && cpufreq_device->cool_dev == cdev) {
>>> +                       ret = 0;
>>> +                       break;
>>> +               }
>>> +       }
>>> +       if (!ret)
>>> +               ret = cpufreq_apply_cooling(cpufreq_device, state);
>>> +
>>> +       mutex_unlock(&cooling_cpufreq_lock);
>>> +
>>> +       return ret;
>>> +}
>>> +
>>> +/*Bind cpufreq callbacks to thermal cooling device ops*/
>>> +static struct thermal_cooling_device_ops const cpufreq_cooling_ops = {
>>> +       .get_max_state = cpufreq_get_max_state,
>>> +       .get_cur_state = cpufreq_get_cur_state,
>>> +       .set_cur_state = cpufreq_set_cur_state,
>>> +};
>>> +
>>> +/*Notifier for cpufreq policy change*/
>>> +static struct notifier_block thermal_cpufreq_notifier_block = {
>>> +       .notifier_call = cpufreq_thermal_notifier,
>>> +};
>>> +
>>> +/**
>>> + * cpufreq_cooling_register - function to create cpufreq cooling device.
>>> + * @tab_ptr: table ptr containing the maximum value of frequency to be clipped
>>> + *     for each cooling state.
>>> + * @tab_size: count of entries in the above table.
>>> + *     happen.
>>> + */
>>> +struct thermal_cooling_device *cpufreq_cooling_register(
>>> +       struct freq_clip_table *tab_ptr, unsigned int tab_size)
>>> +{
>>> +       struct thermal_cooling_device *cool_dev;
>>> +       struct cpufreq_cooling_device *cpufreq_dev = NULL;
>>> +       struct freq_clip_table *clip_tab;
>>> +       unsigned int cpufreq_dev_count = 0;
>>> +       char dev_name[THERMAL_NAME_LENGTH];
>>> +       int ret = 0, id = 0, i;
>>> +
>>> +       if (tab_ptr == NULL || tab_size == 0)
>>> +               return ERR_PTR(-EINVAL);
>>> +
>>> +       list_for_each_entry(cpufreq_dev, &cooling_cpufreq_list, node)
>>> +               cpufreq_dev_count++;
>>> +
>>> +       cpufreq_dev = kzalloc(sizeof(struct cpufreq_cooling_device),
>>> +                       GFP_KERNEL);
>>> +       if (!cpufreq_dev)
>>> +               return ERR_PTR(-ENOMEM);
>>> +
>>> +       /*Verify that all the entries of freq_clip_table are present*/
>>> +       for (i = 0; i < tab_size; i++) {
>>> +               clip_tab = ((struct freq_clip_table *)&tab_ptr[i]);
>>> +               if (!clip_tab->freq_clip_max || !clip_tab->mask_val
>>> +                                       || !clip_tab->temp_level) {
>>> +                       kfree(cpufreq_dev);
>>> +                       return ERR_PTR(-EINVAL);
>>> +               }
>>> +               /*
>>> +                *Consolidate all the cpumask for all the individual entries
>>> +                *of the trip table. This is useful in resetting all the
>>> +                *clipped frequencies to the normal level for each cpufreq
>>> +                *cooling device.
>>> +                */
>>> +               cpumask_or(&cpufreq_dev->allowed_cpus,
>>> +                       &cpufreq_dev->allowed_cpus, clip_tab->mask_val);
>>> +       }
>>> +
>>> +       cpufreq_dev->tab_ptr = tab_ptr;
>>> +       cpufreq_dev->tab_size = tab_size;
>>> +
>>> +       ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
>>> +       if (ret) {
>>> +               kfree(cpufreq_dev);
>>> +               return ERR_PTR(-EINVAL);
>>> +       }
>>> +
>>> +       sprintf(dev_name, "thermal-cpufreq-%d", cpufreq_dev->id);
>>> +
>>> +       cool_dev = thermal_cooling_device_register(dev_name, cpufreq_dev,
>>> +                                               &cpufreq_cooling_ops);
>>> +       if (!cool_dev) {
>>> +               release_idr(&cpufreq_idr, cpufreq_dev->id);
>>> +               kfree(cpufreq_dev);
>>> +               return ERR_PTR(-EINVAL);
>>> +       }
>>> +       cpufreq_dev->id = id;
>>> +       cpufreq_dev->cool_dev = cool_dev;
>>> +       mutex_lock(&cooling_cpufreq_lock);
>>> +       list_add_tail(&cpufreq_dev->node, &cooling_cpufreq_list);
>>> +
>>> +       /*Register the notifier for first cpufreq cooling device*/
>>> +       if (cpufreq_dev_count == 0)
>>> +               cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
>>> +                                               CPUFREQ_POLICY_NOTIFIER);
>>> +
>>> +       mutex_unlock(&cooling_cpufreq_lock);
>>> +       return cool_dev;
>>> +}
>>> +EXPORT_SYMBOL(cpufreq_cooling_register);
>>> +
>>> +/**
>>> + * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
>>> + * @cdev: thermal cooling device pointer.
>>> + */
>>> +void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
>>> +{
>>> +       struct cpufreq_cooling_device *cpufreq_dev = NULL;
>>> +       unsigned int cpufreq_dev_count = 0;
>>> +
>>> +       mutex_lock(&cooling_cpufreq_lock);
>>> +       list_for_each_entry(cpufreq_dev, &cooling_cpufreq_list, node) {
>>> +               if (cpufreq_dev && cpufreq_dev->cool_dev == cdev)
>>> +                       break;
>>> +               cpufreq_dev_count++;
>>> +       }
>>> +
>>> +       if (!cpufreq_dev || cpufreq_dev->cool_dev != cdev) {
>>> +               mutex_unlock(&cooling_cpufreq_lock);
>>> +               return;
>>> +       }
>>> +
>>> +       list_del(&cpufreq_dev->node);
>>> +
>>> +       /*Unregister the notifier for the last cpufreq cooling device*/
>>> +       if (cpufreq_dev_count == 1) {
>>> +               cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
>>> +                                       CPUFREQ_POLICY_NOTIFIER);
>>> +       }
>>> +       mutex_unlock(&cooling_cpufreq_lock);
>>> +       thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
>>> +       release_idr(&cpufreq_idr, cpufreq_dev->id);
>>> +       kfree(cpufreq_dev);
>>> +}
>>> +EXPORT_SYMBOL(cpufreq_cooling_unregister);
>>> diff --git a/include/linux/cpu_cooling.h b/include/linux/cpu_cooling.h
>>> new file mode 100644
>>> index 0000000..ed6c096
>>> --- /dev/null
>>> +++ b/include/linux/cpu_cooling.h
>>> @@ -0,0 +1,99 @@
>>> +/*
>>> + *  linux/include/linux/cpu_cooling.h
>>> + *
>>> + *  Copyright (C) 2012 Samsung Electronics Co., Ltd(http://www.samsung.com)
>>> + *  Copyright (C) 2012  Amit Daniel <amit.kachhap@linaro.org>
>>> + *
>>> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>> + *  This program is free software; you can redistribute it and/or modify
>>> + *  it under the terms of the GNU General Public License as published by
>>> + *  the Free Software Foundation; version 2 of the License.
>>> + *
>>> + *  This program is distributed in the hope that it will be useful, but
>>> + *  WITHOUT ANY WARRANTY; without even the implied warranty of
>>> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>>> + *  General Public License for more details.
>>> + *
>>> + *  You should have received a copy of the GNU General Public License along
>>> + *  with this program; if not, write to the Free Software Foundation, Inc.,
>>> + *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
>>> + *
>>> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>> + */
>>> +
>>> +#ifndef __CPU_COOLING_H__
>>> +#define __CPU_COOLING_H__
>>> +
>>> +#include <linux/thermal.h>
>>> +
>>> +#define CPUFREQ_COOLING_START          0
>>> +#define CPUFREQ_COOLING_STOP           1
>>> +
>>> +/**
>>> + * struct freq_clip_table
>>> + * @freq_clip_max: maximum frequency allowed for this cooling state.
>>> + * @temp_level: Temperature level at which the temperature clipping will
>>> + *     happen.
>>> + * @mask_val: cpumask of the allowed cpu's where the clipping will take place.
>>> + *
>>> + * This structure is required to be filled and passed to the
>>> + * cpufreq_cooling_unregister function.
>>> + */
>>> +struct freq_clip_table {
>>> +       unsigned int freq_clip_max;
>>> +       unsigned int temp_level;
>>> +       const struct cpumask *mask_val;
>>> +};
>>> +
>>> +/**
>>> + * cputherm_register_notifier - Register a notifier with cpu cooling interface.
>>> + * @nb:        struct notifier_block * with callback info.
>>> + * @list: integer value for which notification is needed. possible values are
>>> + *     CPUFREQ_COOLING_TYPE and CPUHOTPLUG_COOLING_TYPE.
>>
>> CPUFREQ_COOLING_TYPE and CPUHOTPLUG_COOLING_TYPE should be changed to
>> CPUFREQ_COOLING_START CPUFREQ_COOLING_STOP, right?
>>
>>> + *
>>> + * This exported function registers a driver with cpu cooling layer. The driver
>>> + * will be notified when any cpu cooling action is called.
>>> + */
>>> +int cputherm_register_notifier(struct notifier_block *nb, unsigned int list);
>>> +
>>> +/**
>>> + * cputherm_unregister_notifier - Un-register a notifier.
>>> + * @nb:        struct notifier_block * with callback info.
>>> + * @list: integer value for which notification is needed. values possible are
>>> + *     CPUFREQ_COOLING_TYPE.
>>
>> Should be changed to CPUFREQ_COOLING_START, CPUFREQ_COOLING_STOP, right?
>>
>>> + *
>>> + * This exported function un-registers a driver with cpu cooling layer.
>>> + */
>>> +int cputherm_unregister_notifier(struct notifier_block *nb, unsigned int list);
>>> +
>>> +#ifdef CONFIG_CPU_FREQ
>>
>> Consider changing this to "#ifdef CPU_THERMAL"  A platform thermal
>> driver may want to always call this function as its cpu cooling
>> mechanism but it should still function without the cpu_cooling being
>> enabled.  In this case, the platform thermal driver would only provide
>> temperature readings and critical trip point handling.  But if the
>> platform happened may have CONFIG_CPU_FREQ enabled, a build error
>> would occur in the current implementation.
>
> I agree here. It makes more sense to have the check against CPU_THERMAL
>
>>
>> (the CONFIG_CPU_FREQ requirement will be met by CPU_THERMAL being
>> enabled since it also implies CONFIG_CPU_FREQ being enabled per the
>> Kconfig dependency)
>
> True.
>
>>
>>> +/**
>>> + * cpufreq_cooling_register - function to create cpufreq cooling device.
>>> + * @tab_ptr: table ptr containing the maximum value of frequency to be clipped
>>> + *     for each cooling state.
>>> + * @tab_size: count of entries in the above table.
>>> + * @mask_val: cpumask containing the allowed cpu's where frequency clipping can
>>> + *     happen.
>>> + */
>>> +struct thermal_cooling_device *cpufreq_cooling_register(
>>> +       struct freq_clip_table *tab_ptr, unsigned int tab_size);
>>> +
>>> +/**
>>> + * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
>>> + * @cdev: thermal cooling device pointer.
>>> + */
>>> +void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev);
>>> +#else /*!CONFIG_CPU_FREQ*/
>>
>> Modify comment if above suggestion is taken.
>>
>>> +static inline struct thermal_cooling_device *cpufreq_cooling_register(
>>> +       struct freq_clip_table *tab_ptr, unsigned int tab_size);
>
> The above semicollon will cause a build error in case this path of the
> ifdef is taken.
>
>>> +{
>>> +       return NULL;
>>> +}
>>> +static inline void cpufreq_cooling_unregister(
>>> +               struct thermal_cooling_device *cdev)
>>> +{
>>> +       return;
>>> +}
>>> +#endif /*CONFIG_CPU_FREQ*/
>>
>> Modify comment if above suggestion is taken.
>>
>>> +
>>> +#endif /* __CPU_COOLING_H__ */
>>> --
>>> 1.7.1
>>>
>>>
>>> _______________________________________________
>>> linaro-dev mailing list
>>> linaro-dev@lists.linaro.org
>>> http://lists.linaro.org/mailman/listinfo/linaro-dev
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
>
>
> --
>
> Eduardo Valentin
> --
> To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
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On 12 May 2012 17:40, Amit Daniel Kachhap <amit.kachhap@linaro.org> wrote:

> This patch adds support for generic cpu thermal cooling low level
> implementations using frequency scaling up/down based on the registration
> parameters. Different cpu related cooling devices can be registered by the
> user and the binding of these cooling devices to the corresponding
> trip points can be easily done as the registration APIs return the
> cooling device pointer. The user of these APIs are responsible for
> passing clipping frequency . The drivers can also register to recieve
> notification about any cooling action called.
>
> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@linaro.org>
> ---
>  Documentation/thermal/cpu-cooling-api.txt |   60 ++++
>  drivers/thermal/Kconfig                   |   11 +
>  drivers/thermal/Makefile                  |    3 +-
>  drivers/thermal/cpu_cooling.c             |  483
> +++++++++++++++++++++++++++++
>  include/linux/cpu_cooling.h               |   99 ++++++
>  5 files changed, 655 insertions(+), 1 deletions(-)
>  create mode 100644 Documentation/thermal/cpu-cooling-api.txt
>  create mode 100644 drivers/thermal/cpu_cooling.c
>  create mode 100644 include/linux/cpu_cooling.h
>
> diff --git a/Documentation/thermal/cpu-cooling-api.txt
> b/Documentation/thermal/cpu-cooling-api.txt
> new file mode 100644
> index 0000000..557adb8
> --- /dev/null
> +++ b/Documentation/thermal/cpu-cooling-api.txt
> @@ -0,0 +1,60 @@
> +CPU cooling APIs How To
> +===================================
> +
> +Written by Amit Daniel Kachhap <amit.kachhap@linaro.org>
> +
> +Updated: 12 May 2012
> +
> +Copyright (c)  2012 Samsung Electronics Co., Ltd(http://www.samsung.com)
> +
> +0. Introduction
> +
> +The generic cpu cooling(freq clipping, cpuhotplug etc) provides
> +registration/unregistration APIs to the caller. The binding of the cooling
> +devices to the trip point is left for the user. The registration APIs
> returns
> +the cooling device pointer.
> +
> +1. cpu cooling APIs
> +
> +1.1 cpufreq registration/unregistration APIs
> +1.1.1 struct thermal_cooling_device *cpufreq_cooling_register(
> +       struct freq_clip_table *tab_ptr, unsigned int tab_size)
> +
> +    This interface function registers the cpufreq cooling device with the
> name
> +    "thermal-cpufreq-%x". This api can support multiple instances of
> cpufreq
> +    cooling devices.
> +
> +    tab_ptr: The table containing the maximum value of frequency to be
> clipped
> +    for each cooling state.
> +       .freq_clip_max: Value of frequency to be clipped for each allowed
> +        cpus.
> +       .temp_level: Temperature level at which the frequency clamping will
> +       happen.
> +       .mask_val: cpumask of the allowed cpu's
> +    tab_size: the total number of cpufreq cooling states.
> +
> +1.1.2 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
> +
> +    This interface function unregisters the "thermal-cpufreq-%x" cooling
> device.
> +
> +    cdev: Cooling device pointer which has to be unregistered.
> +
> +
> +1.2 CPU cooling action notifier register/unregister interface
> +1.2.1 int cputherm_register_notifier(struct notifier_block *nb,
> +       unsigned int list)
> +
> +    This interface registers a driver with cpu cooling layer. The driver
> will
> +    be notified when any cpu cooling action is called.
> +
> +    nb: notifier function to register
> +    list: CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP
> +
> +1.2.2 int cputherm_unregister_notifier(struct notifier_block *nb,
> +       unsigned int list)
> +
> +    This interface registers a driver with cpu cooling layer. The driver
> will
> +    be notified when any cpu cooling action is called.
> +
> +    nb: notifier function to register
> +    list: CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP
> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
> index 514a691..d9c529f 100644
> --- a/drivers/thermal/Kconfig
> +++ b/drivers/thermal/Kconfig
> @@ -19,6 +19,17 @@ config THERMAL_HWMON
>         depends on HWMON=y || HWMON=THERMAL
>         default y
>
> +config CPU_THERMAL
> +       bool "generic cpu cooling support"
> +       depends on THERMAL && CPU_FREQ
> +       help
> +         This implements the generic cpu cooling mechanism through
> frequency
> +         reduction, cpu hotplug and any other ways of reducing
> temperature. An
> +         ACPI version of this already
> exists(drivers/acpi/processor_thermal.c).
> +         This will be useful for platforms using the generic thermal
> interface
> +         and not the ACPI interface.
> +         If you want this support, you should say Y or M here.
> +
>  config SPEAR_THERMAL
>         bool "SPEAr thermal sensor driver"
>         depends on THERMAL
> diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
> index a9fff0b..30c456c 100644
> --- a/drivers/thermal/Makefile
> +++ b/drivers/thermal/Makefile
> @@ -3,4 +3,5 @@
>  #
>
>  obj-$(CONFIG_THERMAL)          += thermal_sys.o
> -obj-$(CONFIG_SPEAR_THERMAL)            += spear_thermal.o
> \ No newline at end of file
> +obj-$(CONFIG_CPU_THERMAL)       += cpu_cooling.o
> +obj-$(CONFIG_SPEAR_THERMAL)            += spear_thermal.o
> diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
> new file mode 100644
> index 0000000..c40d9a0
> --- /dev/null
> +++ b/drivers/thermal/cpu_cooling.c
> @@ -0,0 +1,483 @@
> +/*
> + *  linux/drivers/thermal/cpu_cooling.c
> + *
> + *  Copyright (C) 2012 Samsung Electronics Co., Ltd(
> http://www.samsung.com)
> + *  Copyright (C) 2012  Amit Daniel <amit.kachhap@linaro.org>
> + *
> + *
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> + *  This program is free software; you can redistribute it and/or modify
> + *  it under the terms of the GNU General Public License as published by
> + *  the Free Software Foundation; version 2 of the License.
> + *
> + *  This program is distributed in the hope that it will be useful, but
> + *  WITHOUT ANY WARRANTY; without even the implied warranty of
> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + *  General Public License for more details.
> + *
> + *  You should have received a copy of the GNU General Public License
> along
> + *  with this program; if not, write to the Free Software Foundation,
> Inc.,
> + *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
> + *
> + *
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> + */
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/thermal.h>
> +#include <linux/platform_device.h>
> +#include <linux/cpufreq.h>
> +#include <linux/err.h>
> +#include <linux/slab.h>
> +#include <linux/cpu.h>
> +#include <linux/cpu_cooling.h>
> +
> +/**
> + * struct cpufreq_cooling_device
> + * @id: unique integer value corresponding to each cpufreq_cooling_device
> + *     registered.
> + * @cool_dev: thermal_cooling_device pointer to keep track of the the
> + *     egistered cooling device.
> + * @tab_ptr: freq_clip_table table containing the maximum value of
> frequency to
> + *     be set for different cooling state.
> + * @tab_size: integer value representing a count of the above table.
> + * @cpufreq_state: integer value representing the current state of cpufreq
> + *     cooling devices.
> + * @allowed_cpus: all the cpus involved for this cpufreq_cooling_device.
> + * @node: list_head to link all cpufreq_cooling_device together.
> + *
> + * This structure is required for keeping information of each
> + * cpufreq_cooling_device registered as a list whose head is represented
> by
> + * cooling_cpufreq_list. In order to prevent corruption of this list a
> + * mutex lock cooling_cpufreq_lock is used.
> + */
> +struct cpufreq_cooling_device {
> +       int id;
> +       struct thermal_cooling_device *cool_dev;
> +       struct freq_clip_table *tab_ptr;
> +       unsigned int tab_size;
> +       unsigned int cpufreq_state;
> +       struct cpumask allowed_cpus;
> +       struct list_head node;
> +};
> +static LIST_HEAD(cooling_cpufreq_list);
> +static DEFINE_MUTEX(cooling_cpufreq_lock);
> +static DEFINE_IDR(cpufreq_idr);
> +
> +/*per cpu variable to store the previous max frequency allowed*/
> +static DEFINE_PER_CPU(unsigned int, max_policy_freq);
> +
> +/*notify_table passes value to the CPUFREQ_ADJUST callback function.*/
> +#define NOTIFY_INVALID NULL
> +static struct freq_clip_table *notify_table;
> +
> +/*Head of the blocking notifier chain to inform about frequency clamping*/
> +static BLOCKING_NOTIFIER_HEAD(cputherm_state_notifier_list);
> +
> +/**
> + * get_idr - function to get a unique id.
> + * @idr: struct idr * handle used to create a id.
> + * @id: int * value generated by this function.
> + */
> +static int get_idr(struct idr *idr, int *id)
> +{
> +       int err;
> +again:
> +       if (unlikely(idr_pre_get(idr, GFP_KERNEL) == 0))
> +               return -ENOMEM;
> +
> +       mutex_lock(&cooling_cpufreq_lock);
> +       err = idr_get_new(idr, NULL, id);
> +       mutex_unlock(&cooling_cpufreq_lock);
> +
> +       if (unlikely(err == -EAGAIN))
> +               goto again;
> +       else if (unlikely(err))
> +               return err;
> +
> +       *id = *id & MAX_ID_MASK;
> +       return 0;
> +}
> +
> +/**
> + * release_idr - function to free the unique id.
> + * @idr: struct idr * handle used for creating the id.
> + * @id: int value representing the unique id.
> + */
> +static void release_idr(struct idr *idr, int id)
> +{
> +       mutex_lock(&cooling_cpufreq_lock);
> +       idr_remove(idr, id);
> +       mutex_unlock(&cooling_cpufreq_lock);
> +}
> +
> +/**
> + * cputherm_register_notifier - Register a notifier with cpu cooling
> interface.
> + * @nb:        struct notifier_block * with callback info.
> + * @list: integer value for which notification is needed. possible values
> are
> + *     CPUFREQ_COOLING_START and CPUFREQ_COOLING_STOP.
> + *
> + * This exported function registers a driver with cpu cooling layer. The
> driver
> + * will be notified when any cpu cooling action is called.
> + */
> +int cputherm_register_notifier(struct notifier_block *nb, unsigned int
> list)
> +{
> +       int ret = 0;
> +
> +       switch (list) {
> +       case CPUFREQ_COOLING_START:
> +       case CPUFREQ_COOLING_STOP:
> +               ret = blocking_notifier_chain_register(
> +                               &cputherm_state_notifier_list, nb);
> +               break;
> +       default:
> +               ret = -EINVAL;
> +       }
> +       return ret;
> +}
> +EXPORT_SYMBOL(cputherm_register_notifier);
> +
> +/**
> + * cputherm_unregister_notifier - Un-register a notifier.
> + * @nb:        struct notifier_block * with callback info.
> + * @list: integer value for which notification is needed. values possible
> are
> + *     CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP.
> + *
> + * This exported function un-registers a driver with cpu cooling layer.
> + */
> +int cputherm_unregister_notifier(struct notifier_block *nb, unsigned int
> list)
> +{
> +       int ret = 0;
> +
> +       switch (list) {
> +       case CPUFREQ_COOLING_START:
> +       case CPUFREQ_COOLING_STOP:
> +               ret = blocking_notifier_chain_unregister(
> +                               &cputherm_state_notifier_list, nb);
> +               break;
> +       default:
> +               ret = -EINVAL;
> +       }
> +       return ret;
> +}
> +EXPORT_SYMBOL(cputherm_unregister_notifier);
> +
> +/*Below codes defines functions to be used for cpufreq as cooling device*/
> +
> +/**
> + * is_cpufreq_valid - function to check if a cpu has frequency transition
> policy.
> + * @cpu: cpu for which check is needed.
> + */
> +static int is_cpufreq_valid(int cpu)
> +{
> +       struct cpufreq_policy policy;
> +       return !cpufreq_get_policy(&policy, cpu);
> +}
> +
> +/**
> + * cpufreq_apply_cooling - function to apply frequency clipping.
> + * @cpufreq_device: cpufreq_cooling_device pointer containing frequency
> + *     clipping data.
> + * @cooling_state: value of the cooling state.
> + */
> +static int cpufreq_apply_cooling(struct cpufreq_cooling_device
> *cpufreq_device,
> +                               unsigned long cooling_state)
> +{
> +       unsigned int event, cpuid, state;
> +       struct freq_clip_table *th_table, *table_ptr;
> +       const struct cpumask *maskPtr = &cpufreq_device->allowed_cpus;
> +       struct cpufreq_cooling_device *cpufreq_ptr;
> +
> +       if (cooling_state > cpufreq_device->tab_size)
> +               return -EINVAL;
> +
> +       /*Check if the old cooling action is same as new cooling action*/
> +       if (cpufreq_device->cpufreq_state == cooling_state)
> +               return 0;
> +
> +       /*pass cooling table info to the cpufreq_thermal_notifier
> callback*/
> +       notify_table = NOTIFY_INVALID;
> +
> +       if (cooling_state > 0) {
> +               th_table = &(cpufreq_device->tab_ptr[cooling_state - 1]);
> +               notify_table = th_table;
> +       }
> +
> +       /*check if any lower clip frequency active in other
> cpufreq_device's*/
> +       list_for_each_entry(cpufreq_ptr, &cooling_cpufreq_list, node) {
> +
> +               state = cpufreq_ptr->cpufreq_state;
> +               if (state == 0 || cpufreq_ptr == cpufreq_device)
> +                       continue;
> +
> +               if (!cpumask_equal(&cpufreq_ptr->allowed_cpus,
> +                               &cpufreq_device->allowed_cpus))
> +                       continue;
> +
> +               table_ptr = &(cpufreq_ptr->tab_ptr[state - 1]);
> +               if (notify_table == NULL ||
> +                               (table_ptr->freq_clip_max <
> +                               notify_table->freq_clip_max))
> +                       notify_table =  table_ptr;
> +       }
> +
> +       cpufreq_device->cpufreq_state = cooling_state;
> +
> +       if (notify_table != NOTIFY_INVALID) {
> +               event = CPUFREQ_COOLING_START;
> +               maskPtr = notify_table->mask_val;
> +       } else {
> +               event = CPUFREQ_COOLING_STOP;
> +       }
> +
> +       blocking_notifier_call_chain(&cputherm_state_notifier_list,
> +                                               event, notify_table);
> +
> +       for_each_cpu(cpuid, maskPtr) {
> +               if (is_cpufreq_valid(cpuid))
> +                       cpufreq_update_policy(cpuid);
> +       }
> +
> +       notify_table = NOTIFY_INVALID;
> +
> +       return 0;
> +}
> +
> +/**
> + * cpufreq_thermal_notifier - notifier callback for cpufreq policy change.
> + * @nb:        struct notifier_block * with callback info.
> + * @event: value showing cpufreq event for which this function invoked.
> + * @data: callback-specific data
> + */
> +static int cpufreq_thermal_notifier(struct notifier_block *nb,
> +                                       unsigned long event, void *data)
> +{
> +       struct cpufreq_policy *policy = data;
> +       unsigned long max_freq = 0;
> +
> +       if (event != CPUFREQ_ADJUST)
> +               return 0;
> +
> +       if (notify_table != NOTIFY_INVALID) {
> +               max_freq = notify_table->freq_clip_max;
> +
> +               if (!per_cpu(max_policy_freq, policy->cpu))
> +                       per_cpu(max_policy_freq, policy->cpu) =
> policy->max;
> +       } else {
> +               if (per_cpu(max_policy_freq, policy->cpu)) {
> +                       max_freq = per_cpu(max_policy_freq, policy->cpu);
> +                       per_cpu(max_policy_freq, policy->cpu) = 0;
> +               } else {
> +                       max_freq = policy->max;
> +               }
> +       }
> +
> +       /* Never exceed user_policy.max*/
> +       if (max_freq > policy->user_policy.max)
> +               max_freq = policy->user_policy.max;
> +
> +       if (policy->max != max_freq)
> +               cpufreq_verify_within_limits(policy, 0, max_freq);
> +
> +       return 0;
> +}
> +
> +/*
> + * cpufreq cooling device callback functions are defined below
> + */
> +
> +/**
> + * cpufreq_get_max_state - callback function to get the max cooling state.
> + * @cdev: thermal cooling device pointer.
> + * @state: fill this variable with the max cooling state.
> + */
> +static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
> +                                unsigned long *state)
> +{
> +       int ret = -EINVAL;
> +       struct cpufreq_cooling_device *cpufreq_device;
> +
> +       mutex_lock(&cooling_cpufreq_lock);
> +       list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node) {
> +               if (cpufreq_device && cpufreq_device->cool_dev == cdev) {
> +                       *state = cpufreq_device->tab_size;
> +                       ret = 0;
> +                       break;
> +               }
> +       }
> +       mutex_unlock(&cooling_cpufreq_lock);
> +       return ret;
> +}
> +
> +/**
> + * cpufreq_get_cur_state - callback function to get the current cooling
> state.
> + * @cdev: thermal cooling device pointer.
> + * @state: fill this variable with the current cooling state.
> + */
> +static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
> +                                unsigned long *state)
> +{
> +       int ret = -EINVAL;
> +       struct cpufreq_cooling_device *cpufreq_device;
> +
> +       mutex_lock(&cooling_cpufreq_lock);
> +       list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node) {
> +               if (cpufreq_device && cpufreq_device->cool_dev == cdev) {
> +                       *state = cpufreq_device->cpufreq_state;
> +                       ret = 0;
> +                       break;
> +               }
> +       }
> +       mutex_unlock(&cooling_cpufreq_lock);
> +       return ret;
> +}
> +
> +/**
> + * cpufreq_set_cur_state - callback function to set the current cooling
> state.
> + * @cdev: thermal cooling device pointer.
> + * @state: set this variable to the current cooling state.
> + */
> +static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
> +                                unsigned long state)
> +{
> +       int ret = -EINVAL;
> +       struct cpufreq_cooling_device *cpufreq_device;
> +
> +       mutex_lock(&cooling_cpufreq_lock);
> +       list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node) {
> +               if (cpufreq_device && cpufreq_device->cool_dev == cdev) {
> +                       ret = 0;
> +                       break;
> +               }
> +       }
> +       if (!ret)
> +               ret = cpufreq_apply_cooling(cpufreq_device, state);
> +
> +       mutex_unlock(&cooling_cpufreq_lock);
> +
> +       return ret;
> +}
> +
> +/*Bind cpufreq callbacks to thermal cooling device ops*/
> +static struct thermal_cooling_device_ops const cpufreq_cooling_ops = {
> +       .get_max_state = cpufreq_get_max_state,
> +       .get_cur_state = cpufreq_get_cur_state,
> +       .set_cur_state = cpufreq_set_cur_state,
> +};
> +
> +/*Notifier for cpufreq policy change*/
> +static struct notifier_block thermal_cpufreq_notifier_block = {
> +       .notifier_call = cpufreq_thermal_notifier,
> +};
> +
> +/**
> + * cpufreq_cooling_register - function to create cpufreq cooling device.
> + * @tab_ptr: table ptr containing the maximum value of frequency to be
> clipped
> + *     for each cooling state.
> + * @tab_size: count of entries in the above table.
> + *     happen.
> + */
> +struct thermal_cooling_device *cpufreq_cooling_register(
> +       struct freq_clip_table *tab_ptr, unsigned int tab_size)
> +{
> +       struct thermal_cooling_device *cool_dev;
> +       struct cpufreq_cooling_device *cpufreq_dev = NULL;
> +       struct freq_clip_table *clip_tab;
> +       unsigned int cpufreq_dev_count = 0;
> +       char dev_name[THERMAL_NAME_LENGTH];
> +       int ret = 0, id = 0, i;
> +
> +       if (tab_ptr == NULL || tab_size == 0)
> +               return ERR_PTR(-EINVAL);
> +
> +       list_for_each_entry(cpufreq_dev, &cooling_cpufreq_list, node)
> +               cpufreq_dev_count++;
> +
> +       cpufreq_dev = kzalloc(sizeof(struct cpufreq_cooling_device),
> +                       GFP_KERNEL);
> +       if (!cpufreq_dev)
> +               return ERR_PTR(-ENOMEM);
> +
> +       /*Verify that all the entries of freq_clip_table are present*/
> +       for (i = 0; i < tab_size; i++) {
> +               clip_tab = ((struct freq_clip_table *)&tab_ptr[i]);
> +               if (!clip_tab->freq_clip_max || !clip_tab->mask_val
> +                                       || !clip_tab->temp_level) {
>
About  clip_tab->temp_level:
I'd like to remove this variable checking, because as suggested by Vincent
Guittot, it is better to separate cooling devices
and thermal zone, thus we can add/remove cooling devices
freely/dynamically. In such case, a cooling device doesn't
know any temp_level before binding--the binding condition is name matching,
what's more, the cooling device should not
know much data of other devices.

+                       kfree(cpufreq_dev);
> +                       return ERR_PTR(-EINVAL);
> +               }
> +               /*
> +                *Consolidate all the cpumask for all the individual
> entries
> +                *of the trip table. This is useful in resetting all the
> +                *clipped frequencies to the normal level for each cpufreq
> +                *cooling device.
> +                */
> +               cpumask_or(&cpufreq_dev->allowed_cpus,
> +                       &cpufreq_dev->allowed_cpus, clip_tab->mask_val);
> +       }
> +
> +       cpufreq_dev->tab_ptr = tab_ptr;
> +       cpufreq_dev->tab_size = tab_size;
> +
> +       ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
> +       if (ret) {
> +               kfree(cpufreq_dev);
> +               return ERR_PTR(-EINVAL);
> +       }
> +
> +       sprintf(dev_name, "thermal-cpufreq-%d", cpufreq_dev->id);
> +
> +       cool_dev = thermal_cooling_device_register(dev_name, cpufreq_dev,
> +                                               &cpufreq_cooling_ops);
> +       if (!cool_dev) {
> +               release_idr(&cpufreq_idr, cpufreq_dev->id);
> +               kfree(cpufreq_dev);
> +               return ERR_PTR(-EINVAL);
> +       }
> +       cpufreq_dev->id = id;
> +       cpufreq_dev->cool_dev = cool_dev;
> +       mutex_lock(&cooling_cpufreq_lock);
> +       list_add_tail(&cpufreq_dev->node, &cooling_cpufreq_list);
> +
> +       /*Register the notifier for first cpufreq cooling device*/
> +       if (cpufreq_dev_count == 0)
> +               cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
> +                                               CPUFREQ_POLICY_NOTIFIER);
> +
> +       mutex_unlock(&cooling_cpufreq_lock);
> +       return cool_dev;
> +}
> +EXPORT_SYMBOL(cpufreq_cooling_register);
> +
> +/**
> + * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
> + * @cdev: thermal cooling device pointer.
> + */
> +void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
> +{
> +       struct cpufreq_cooling_device *cpufreq_dev = NULL;
> +       unsigned int cpufreq_dev_count = 0;
> +
> +       mutex_lock(&cooling_cpufreq_lock);
> +       list_for_each_entry(cpufreq_dev, &cooling_cpufreq_list, node) {
> +               if (cpufreq_dev && cpufreq_dev->cool_dev == cdev)
> +                       break;
> +               cpufreq_dev_count++;
> +       }
> +
> +       if (!cpufreq_dev || cpufreq_dev->cool_dev != cdev) {
> +               mutex_unlock(&cooling_cpufreq_lock);
> +               return;
> +       }
> +
> +       list_del(&cpufreq_dev->node);
> +
> +       /*Unregister the notifier for the last cpufreq cooling device*/
> +       if (cpufreq_dev_count == 1) {
> +
> cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
> +                                       CPUFREQ_POLICY_NOTIFIER);
> +       }
> +       mutex_unlock(&cooling_cpufreq_lock);
> +       thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
> +       release_idr(&cpufreq_idr, cpufreq_dev->id);
> +       kfree(cpufreq_dev);
> +}
> +EXPORT_SYMBOL(cpufreq_cooling_unregister);
> diff --git a/include/linux/cpu_cooling.h b/include/linux/cpu_cooling.h
> new file mode 100644
> index 0000000..ed6c096
> --- /dev/null
> +++ b/include/linux/cpu_cooling.h
> @@ -0,0 +1,99 @@
> +/*
> + *  linux/include/linux/cpu_cooling.h
> + *
> + *  Copyright (C) 2012 Samsung Electronics Co., Ltd(
> http://www.samsung.com)
> + *  Copyright (C) 2012  Amit Daniel <amit.kachhap@linaro.org>
> + *
> + *
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> + *  This program is free software; you can redistribute it and/or modify
> + *  it under the terms of the GNU General Public License as published by
> + *  the Free Software Foundation; version 2 of the License.
> + *
> + *  This program is distributed in the hope that it will be useful, but
> + *  WITHOUT ANY WARRANTY; without even the implied warranty of
> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + *  General Public License for more details.
> + *
> + *  You should have received a copy of the GNU General Public License
> along
> + *  with this program; if not, write to the Free Software Foundation,
> Inc.,
> + *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
> + *
> + *
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> + */
> +
> +#ifndef __CPU_COOLING_H__
> +#define __CPU_COOLING_H__
> +
> +#include <linux/thermal.h>
> +
> +#define CPUFREQ_COOLING_START          0
> +#define CPUFREQ_COOLING_STOP           1
> +
> +/**
> + * struct freq_clip_table
> + * @freq_clip_max: maximum frequency allowed for this cooling state.
> + * @temp_level: Temperature level at which the temperature clipping will
> + *     happen.
> + * @mask_val: cpumask of the allowed cpu's where the clipping will take
> place.
> + *
> + * This structure is required to be filled and passed to the
> + * cpufreq_cooling_unregister function.
> + */
> +struct freq_clip_table {
> +       unsigned int freq_clip_max;
> +       unsigned int temp_level;
> +       const struct cpumask *mask_val;
> +};
> +
> +/**
> + * cputherm_register_notifier - Register a notifier with cpu cooling
> interface.
> + * @nb:        struct notifier_block * with callback info.
> + * @list: integer value for which notification is needed. possible values
> are
> + *     CPUFREQ_COOLING_TYPE and CPUHOTPLUG_COOLING_TYPE.
> + *
> + * This exported function registers a driver with cpu cooling layer. The
> driver
> + * will be notified when any cpu cooling action is called.
> + */
> +int cputherm_register_notifier(struct notifier_block *nb, unsigned int
> list);
> +
> +/**
> + * cputherm_unregister_notifier - Un-register a notifier.
> + * @nb:        struct notifier_block * with callback info.
> + * @list: integer value for which notification is needed. values possible
> are
> + *     CPUFREQ_COOLING_TYPE.
> + *
> + * This exported function un-registers a driver with cpu cooling layer.
> + */
> +int cputherm_unregister_notifier(struct notifier_block *nb, unsigned int
> list);
> +
> +#ifdef CONFIG_CPU_FREQ
> +/**
> + * cpufreq_cooling_register - function to create cpufreq cooling device.
> + * @tab_ptr: table ptr containing the maximum value of frequency to be
> clipped
> + *     for each cooling state.
> + * @tab_size: count of entries in the above table.
> + * @mask_val: cpumask containing the allowed cpu's where frequency
> clipping can
> + *     happen.
> + */
> +struct thermal_cooling_device *cpufreq_cooling_register(
> +       struct freq_clip_table *tab_ptr, unsigned int tab_size);
> +
> +/**
> + * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
> + * @cdev: thermal cooling device pointer.
> + */
> +void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev);
> +#else /*!CONFIG_CPU_FREQ*/
> +static inline struct thermal_cooling_device *cpufreq_cooling_register(
> +       struct freq_clip_table *tab_ptr, unsigned int tab_size);
> +{
> +       return NULL;
> +}
> +static inline void cpufreq_cooling_unregister(
> +               struct thermal_cooling_device *cdev)
> +{
> +       return;
> +}
> +#endif /*CONFIG_CPU_FREQ*/
> +
> +#endif /* __CPU_COOLING_H__ */
> --
> 1.7.1
>
>
> _______________________________________________
> linaro-dev mailing list
> linaro-dev@lists.linaro.org
> http://lists.linaro.org/mailman/listinfo/linaro-dev
>

On Tue, Jul 10, 2012 at 12:31 PM, Hongbo Zhang <hongbo.zhang@linaro.org> wrote:
>
>
> On 12 May 2012 17:40, Amit Daniel Kachhap <amit.kachhap@linaro.org> wrote:
>>
>> This patch adds support for generic cpu thermal cooling low level
>> implementations using frequency scaling up/down based on the registration
>> parameters. Different cpu related cooling devices can be registered by the
>> user and the binding of these cooling devices to the corresponding
>> trip points can be easily done as the registration APIs return the
>> cooling device pointer. The user of these APIs are responsible for
>> passing clipping frequency . The drivers can also register to recieve
>> notification about any cooling action called.
>>
>> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@linaro.org>
>> ---
>>  Documentation/thermal/cpu-cooling-api.txt |   60 ++++
>>  drivers/thermal/Kconfig                   |   11 +
>>  drivers/thermal/Makefile                  |    3 +-
>>  drivers/thermal/cpu_cooling.c             |  483
>> +++++++++++++++++++++++++++++
>>  include/linux/cpu_cooling.h               |   99 ++++++
>>  5 files changed, 655 insertions(+), 1 deletions(-)
>>  create mode 100644 Documentation/thermal/cpu-cooling-api.txt
>>  create mode 100644 drivers/thermal/cpu_cooling.c
>>  create mode 100644 include/linux/cpu_cooling.h
>>
>> diff --git a/Documentation/thermal/cpu-cooling-api.txt
>> b/Documentation/thermal/cpu-cooling-api.txt
>> new file mode 100644
>> index 0000000..557adb8
>> --- /dev/null
>> +++ b/Documentation/thermal/cpu-cooling-api.txt
>> @@ -0,0 +1,60 @@
>> +CPU cooling APIs How To
>> +===================================
>> +
>> +Written by Amit Daniel Kachhap <amit.kachhap@linaro.org>
>> +
>> +Updated: 12 May 2012
>> +
>> +Copyright (c)  2012 Samsung Electronics Co., Ltd(http://www.samsung.com)
>> +
>> +0. Introduction
>> +
>> +The generic cpu cooling(freq clipping, cpuhotplug etc) provides
>> +registration/unregistration APIs to the caller. The binding of the
>> cooling
>> +devices to the trip point is left for the user. The registration APIs
>> returns
>> +the cooling device pointer.
>> +
>> +1. cpu cooling APIs
>> +
>> +1.1 cpufreq registration/unregistration APIs
>> +1.1.1 struct thermal_cooling_device *cpufreq_cooling_register(
>> +       struct freq_clip_table *tab_ptr, unsigned int tab_size)
>> +
>> +    This interface function registers the cpufreq cooling device with the
>> name
>> +    "thermal-cpufreq-%x". This api can support multiple instances of
>> cpufreq
>> +    cooling devices.
>> +
>> +    tab_ptr: The table containing the maximum value of frequency to be
>> clipped
>> +    for each cooling state.
>> +       .freq_clip_max: Value of frequency to be clipped for each allowed
>> +        cpus.
>> +       .temp_level: Temperature level at which the frequency clamping
>> will
>> +       happen.
>> +       .mask_val: cpumask of the allowed cpu's
>> +    tab_size: the total number of cpufreq cooling states.
>> +
>> +1.1.2 void cpufreq_cooling_unregister(struct thermal_cooling_device
>> *cdev)
>> +
>> +    This interface function unregisters the "thermal-cpufreq-%x" cooling
>> device.
>> +
>> +    cdev: Cooling device pointer which has to be unregistered.
>> +
>> +
>> +1.2 CPU cooling action notifier register/unregister interface
>> +1.2.1 int cputherm_register_notifier(struct notifier_block *nb,
>> +       unsigned int list)
>> +
>> +    This interface registers a driver with cpu cooling layer. The driver
>> will
>> +    be notified when any cpu cooling action is called.
>> +
>> +    nb: notifier function to register
>> +    list: CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP
>> +
>> +1.2.2 int cputherm_unregister_notifier(struct notifier_block *nb,
>> +       unsigned int list)
>> +
>> +    This interface registers a driver with cpu cooling layer. The driver
>> will
>> +    be notified when any cpu cooling action is called.
>> +
>> +    nb: notifier function to register
>> +    list: CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP
>> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
>> index 514a691..d9c529f 100644
>> --- a/drivers/thermal/Kconfig
>> +++ b/drivers/thermal/Kconfig
>> @@ -19,6 +19,17 @@ config THERMAL_HWMON
>>         depends on HWMON=y || HWMON=THERMAL
>>         default y
>>
>> +config CPU_THERMAL
>> +       bool "generic cpu cooling support"
>> +       depends on THERMAL && CPU_FREQ
>> +       help
>> +         This implements the generic cpu cooling mechanism through
>> frequency
>> +         reduction, cpu hotplug and any other ways of reducing
>> temperature. An
>> +         ACPI version of this already
>> exists(drivers/acpi/processor_thermal.c).
>> +         This will be useful for platforms using the generic thermal
>> interface
>> +         and not the ACPI interface.
>> +         If you want this support, you should say Y or M here.
>> +
>>  config SPEAR_THERMAL
>>         bool "SPEAr thermal sensor driver"
>>         depends on THERMAL
>> diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
>> index a9fff0b..30c456c 100644
>> --- a/drivers/thermal/Makefile
>> +++ b/drivers/thermal/Makefile
>> @@ -3,4 +3,5 @@
>>  #
>>
>>  obj-$(CONFIG_THERMAL)          += thermal_sys.o
>> -obj-$(CONFIG_SPEAR_THERMAL)            += spear_thermal.o
>> \ No newline at end of file
>> +obj-$(CONFIG_CPU_THERMAL)       += cpu_cooling.o
>> +obj-$(CONFIG_SPEAR_THERMAL)            += spear_thermal.o
>> diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
>> new file mode 100644
>> index 0000000..c40d9a0
>> --- /dev/null
>> +++ b/drivers/thermal/cpu_cooling.c
>> @@ -0,0 +1,483 @@
>> +/*
>> + *  linux/drivers/thermal/cpu_cooling.c
>> + *
>> + *  Copyright (C) 2012 Samsung Electronics Co.,
>> Ltd(http://www.samsung.com)
>> + *  Copyright (C) 2012  Amit Daniel <amit.kachhap@linaro.org>
>> + *
>> + *
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> + *  This program is free software; you can redistribute it and/or modify
>> + *  it under the terms of the GNU General Public License as published by
>> + *  the Free Software Foundation; version 2 of the License.
>> + *
>> + *  This program is distributed in the hope that it will be useful, but
>> + *  WITHOUT ANY WARRANTY; without even the implied warranty of
>> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>> + *  General Public License for more details.
>> + *
>> + *  You should have received a copy of the GNU General Public License
>> along
>> + *  with this program; if not, write to the Free Software Foundation,
>> Inc.,
>> + *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
>> + *
>> + *
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> + */
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/thermal.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/cpufreq.h>
>> +#include <linux/err.h>
>> +#include <linux/slab.h>
>> +#include <linux/cpu.h>
>> +#include <linux/cpu_cooling.h>
>> +
>> +/**
>> + * struct cpufreq_cooling_device
>> + * @id: unique integer value corresponding to each cpufreq_cooling_device
>> + *     registered.
>> + * @cool_dev: thermal_cooling_device pointer to keep track of the the
>> + *     egistered cooling device.
>> + * @tab_ptr: freq_clip_table table containing the maximum value of
>> frequency to
>> + *     be set for different cooling state.
>> + * @tab_size: integer value representing a count of the above table.
>> + * @cpufreq_state: integer value representing the current state of
>> cpufreq
>> + *     cooling devices.
>> + * @allowed_cpus: all the cpus involved for this cpufreq_cooling_device.
>> + * @node: list_head to link all cpufreq_cooling_device together.
>> + *
>> + * This structure is required for keeping information of each
>> + * cpufreq_cooling_device registered as a list whose head is represented
>> by
>> + * cooling_cpufreq_list. In order to prevent corruption of this list a
>> + * mutex lock cooling_cpufreq_lock is used.
>> + */
>> +struct cpufreq_cooling_device {
>> +       int id;
>> +       struct thermal_cooling_device *cool_dev;
>> +       struct freq_clip_table *tab_ptr;
>> +       unsigned int tab_size;
>> +       unsigned int cpufreq_state;
>> +       struct cpumask allowed_cpus;
>> +       struct list_head node;
>> +};
>> +static LIST_HEAD(cooling_cpufreq_list);
>> +static DEFINE_MUTEX(cooling_cpufreq_lock);
>> +static DEFINE_IDR(cpufreq_idr);
>> +
>> +/*per cpu variable to store the previous max frequency allowed*/
>> +static DEFINE_PER_CPU(unsigned int, max_policy_freq);
>> +
>> +/*notify_table passes value to the CPUFREQ_ADJUST callback function.*/
>> +#define NOTIFY_INVALID NULL
>> +static struct freq_clip_table *notify_table;
>> +
>> +/*Head of the blocking notifier chain to inform about frequency
>> clamping*/
>> +static BLOCKING_NOTIFIER_HEAD(cputherm_state_notifier_list);
>> +
>> +/**
>> + * get_idr - function to get a unique id.
>> + * @idr: struct idr * handle used to create a id.
>> + * @id: int * value generated by this function.
>> + */
>> +static int get_idr(struct idr *idr, int *id)
>> +{
>> +       int err;
>> +again:
>> +       if (unlikely(idr_pre_get(idr, GFP_KERNEL) == 0))
>> +               return -ENOMEM;
>> +
>> +       mutex_lock(&cooling_cpufreq_lock);
>> +       err = idr_get_new(idr, NULL, id);
>> +       mutex_unlock(&cooling_cpufreq_lock);
>> +
>> +       if (unlikely(err == -EAGAIN))
>> +               goto again;
>> +       else if (unlikely(err))
>> +               return err;
>> +
>> +       *id = *id & MAX_ID_MASK;
>> +       return 0;
>> +}
>> +
>> +/**
>> + * release_idr - function to free the unique id.
>> + * @idr: struct idr * handle used for creating the id.
>> + * @id: int value representing the unique id.
>> + */
>> +static void release_idr(struct idr *idr, int id)
>> +{
>> +       mutex_lock(&cooling_cpufreq_lock);
>> +       idr_remove(idr, id);
>> +       mutex_unlock(&cooling_cpufreq_lock);
>> +}
>> +
>> +/**
>> + * cputherm_register_notifier - Register a notifier with cpu cooling
>> interface.
>> + * @nb:        struct notifier_block * with callback info.
>> + * @list: integer value for which notification is needed. possible values
>> are
>> + *     CPUFREQ_COOLING_START and CPUFREQ_COOLING_STOP.
>> + *
>> + * This exported function registers a driver with cpu cooling layer. The
>> driver
>> + * will be notified when any cpu cooling action is called.
>> + */
>> +int cputherm_register_notifier(struct notifier_block *nb, unsigned int
>> list)
>> +{
>> +       int ret = 0;
>> +
>> +       switch (list) {
>> +       case CPUFREQ_COOLING_START:
>> +       case CPUFREQ_COOLING_STOP:
>> +               ret = blocking_notifier_chain_register(
>> +                               &cputherm_state_notifier_list, nb);
>> +               break;
>> +       default:
>> +               ret = -EINVAL;
>> +       }
>> +       return ret;
>> +}
>> +EXPORT_SYMBOL(cputherm_register_notifier);
>> +
>> +/**
>> + * cputherm_unregister_notifier - Un-register a notifier.
>> + * @nb:        struct notifier_block * with callback info.
>> + * @list: integer value for which notification is needed. values possible
>> are
>> + *     CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP.
>> + *
>> + * This exported function un-registers a driver with cpu cooling layer.
>> + */
>> +int cputherm_unregister_notifier(struct notifier_block *nb, unsigned int
>> list)
>> +{
>> +       int ret = 0;
>> +
>> +       switch (list) {
>> +       case CPUFREQ_COOLING_START:
>> +       case CPUFREQ_COOLING_STOP:
>> +               ret = blocking_notifier_chain_unregister(
>> +                               &cputherm_state_notifier_list, nb);
>> +               break;
>> +       default:
>> +               ret = -EINVAL;
>> +       }
>> +       return ret;
>> +}
>> +EXPORT_SYMBOL(cputherm_unregister_notifier);
>> +
>> +/*Below codes defines functions to be used for cpufreq as cooling
>> device*/
>> +
>> +/**
>> + * is_cpufreq_valid - function to check if a cpu has frequency transition
>> policy.
>> + * @cpu: cpu for which check is needed.
>> + */
>> +static int is_cpufreq_valid(int cpu)
>> +{
>> +       struct cpufreq_policy policy;
>> +       return !cpufreq_get_policy(&policy, cpu);
>> +}
>> +
>> +/**
>> + * cpufreq_apply_cooling - function to apply frequency clipping.
>> + * @cpufreq_device: cpufreq_cooling_device pointer containing frequency
>> + *     clipping data.
>> + * @cooling_state: value of the cooling state.
>> + */
>> +static int cpufreq_apply_cooling(struct cpufreq_cooling_device
>> *cpufreq_device,
>> +                               unsigned long cooling_state)
>> +{
>> +       unsigned int event, cpuid, state;
>> +       struct freq_clip_table *th_table, *table_ptr;
>> +       const struct cpumask *maskPtr = &cpufreq_device->allowed_cpus;
>> +       struct cpufreq_cooling_device *cpufreq_ptr;
>> +
>> +       if (cooling_state > cpufreq_device->tab_size)
>> +               return -EINVAL;
>> +
>> +       /*Check if the old cooling action is same as new cooling action*/
>> +       if (cpufreq_device->cpufreq_state == cooling_state)
>> +               return 0;
>> +
>> +       /*pass cooling table info to the cpufreq_thermal_notifier
>> callback*/
>> +       notify_table = NOTIFY_INVALID;
>> +
>> +       if (cooling_state > 0) {
>> +               th_table = &(cpufreq_device->tab_ptr[cooling_state - 1]);
>> +               notify_table = th_table;
>> +       }
>> +
>> +       /*check if any lower clip frequency active in other
>> cpufreq_device's*/
>> +       list_for_each_entry(cpufreq_ptr, &cooling_cpufreq_list, node) {
>> +
>> +               state = cpufreq_ptr->cpufreq_state;
>> +               if (state == 0 || cpufreq_ptr == cpufreq_device)
>> +                       continue;
>> +
>> +               if (!cpumask_equal(&cpufreq_ptr->allowed_cpus,
>> +                               &cpufreq_device->allowed_cpus))
>> +                       continue;
>> +
>> +               table_ptr = &(cpufreq_ptr->tab_ptr[state - 1]);
>> +               if (notify_table == NULL ||
>> +                               (table_ptr->freq_clip_max <
>> +                               notify_table->freq_clip_max))
>> +                       notify_table =  table_ptr;
>> +       }
>> +
>> +       cpufreq_device->cpufreq_state = cooling_state;
>> +
>> +       if (notify_table != NOTIFY_INVALID) {
>> +               event = CPUFREQ_COOLING_START;
>> +               maskPtr = notify_table->mask_val;
>> +       } else {
>> +               event = CPUFREQ_COOLING_STOP;
>> +       }
>> +
>> +       blocking_notifier_call_chain(&cputherm_state_notifier_list,
>> +                                               event, notify_table);
>> +
>> +       for_each_cpu(cpuid, maskPtr) {
>> +               if (is_cpufreq_valid(cpuid))
>> +                       cpufreq_update_policy(cpuid);
>> +       }
>> +
>> +       notify_table = NOTIFY_INVALID;
>> +
>> +       return 0;
>> +}
>> +
>> +/**
>> + * cpufreq_thermal_notifier - notifier callback for cpufreq policy
>> change.
>> + * @nb:        struct notifier_block * with callback info.
>> + * @event: value showing cpufreq event for which this function invoked.
>> + * @data: callback-specific data
>> + */
>> +static int cpufreq_thermal_notifier(struct notifier_block *nb,
>> +                                       unsigned long event, void *data)
>> +{
>> +       struct cpufreq_policy *policy = data;
>> +       unsigned long max_freq = 0;
>> +
>> +       if (event != CPUFREQ_ADJUST)
>> +               return 0;
>> +
>> +       if (notify_table != NOTIFY_INVALID) {
>> +               max_freq = notify_table->freq_clip_max;
>> +
>> +               if (!per_cpu(max_policy_freq, policy->cpu))
>> +                       per_cpu(max_policy_freq, policy->cpu) =
>> policy->max;
>> +       } else {
>> +               if (per_cpu(max_policy_freq, policy->cpu)) {
>> +                       max_freq = per_cpu(max_policy_freq, policy->cpu);
>> +                       per_cpu(max_policy_freq, policy->cpu) = 0;
>> +               } else {
>> +                       max_freq = policy->max;
>> +               }
>> +       }
>> +
>> +       /* Never exceed user_policy.max*/
>> +       if (max_freq > policy->user_policy.max)
>> +               max_freq = policy->user_policy.max;
>> +
>> +       if (policy->max != max_freq)
>> +               cpufreq_verify_within_limits(policy, 0, max_freq);
>> +
>> +       return 0;
>> +}
>> +
>> +/*
>> + * cpufreq cooling device callback functions are defined below
>> + */
>> +
>> +/**
>> + * cpufreq_get_max_state - callback function to get the max cooling
>> state.
>> + * @cdev: thermal cooling device pointer.
>> + * @state: fill this variable with the max cooling state.
>> + */
>> +static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
>> +                                unsigned long *state)
>> +{
>> +       int ret = -EINVAL;
>> +       struct cpufreq_cooling_device *cpufreq_device;
>> +
>> +       mutex_lock(&cooling_cpufreq_lock);
>> +       list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node) {
>> +               if (cpufreq_device && cpufreq_device->cool_dev == cdev) {
>> +                       *state = cpufreq_device->tab_size;
>> +                       ret = 0;
>> +                       break;
>> +               }
>> +       }
>> +       mutex_unlock(&cooling_cpufreq_lock);
>> +       return ret;
>> +}
>> +
>> +/**
>> + * cpufreq_get_cur_state - callback function to get the current cooling
>> state.
>> + * @cdev: thermal cooling device pointer.
>> + * @state: fill this variable with the current cooling state.
>> + */
>> +static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
>> +                                unsigned long *state)
>> +{
>> +       int ret = -EINVAL;
>> +       struct cpufreq_cooling_device *cpufreq_device;
>> +
>> +       mutex_lock(&cooling_cpufreq_lock);
>> +       list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node) {
>> +               if (cpufreq_device && cpufreq_device->cool_dev == cdev) {
>> +                       *state = cpufreq_device->cpufreq_state;
>> +                       ret = 0;
>> +                       break;
>> +               }
>> +       }
>> +       mutex_unlock(&cooling_cpufreq_lock);
>> +       return ret;
>> +}
>> +
>> +/**
>> + * cpufreq_set_cur_state - callback function to set the current cooling
>> state.
>> + * @cdev: thermal cooling device pointer.
>> + * @state: set this variable to the current cooling state.
>> + */
>> +static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
>> +                                unsigned long state)
>> +{
>> +       int ret = -EINVAL;
>> +       struct cpufreq_cooling_device *cpufreq_device;
>> +
>> +       mutex_lock(&cooling_cpufreq_lock);
>> +       list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node) {
>> +               if (cpufreq_device && cpufreq_device->cool_dev == cdev) {
>> +                       ret = 0;
>> +                       break;
>> +               }
>> +       }
>> +       if (!ret)
>> +               ret = cpufreq_apply_cooling(cpufreq_device, state);
>> +
>> +       mutex_unlock(&cooling_cpufreq_lock);
>> +
>> +       return ret;
>> +}
>> +
>> +/*Bind cpufreq callbacks to thermal cooling device ops*/
>> +static struct thermal_cooling_device_ops const cpufreq_cooling_ops = {
>> +       .get_max_state = cpufreq_get_max_state,
>> +       .get_cur_state = cpufreq_get_cur_state,
>> +       .set_cur_state = cpufreq_set_cur_state,
>> +};
>> +
>> +/*Notifier for cpufreq policy change*/
>> +static struct notifier_block thermal_cpufreq_notifier_block = {
>> +       .notifier_call = cpufreq_thermal_notifier,
>> +};
>> +
>> +/**
>> + * cpufreq_cooling_register - function to create cpufreq cooling device.
>> + * @tab_ptr: table ptr containing the maximum value of frequency to be
>> clipped
>> + *     for each cooling state.
>> + * @tab_size: count of entries in the above table.
>> + *     happen.
>> + */
>> +struct thermal_cooling_device *cpufreq_cooling_register(
>> +       struct freq_clip_table *tab_ptr, unsigned int tab_size)
>> +{
>> +       struct thermal_cooling_device *cool_dev;
>> +       struct cpufreq_cooling_device *cpufreq_dev = NULL;
>> +       struct freq_clip_table *clip_tab;
>> +       unsigned int cpufreq_dev_count = 0;
>> +       char dev_name[THERMAL_NAME_LENGTH];
>> +       int ret = 0, id = 0, i;
>> +
>> +       if (tab_ptr == NULL || tab_size == 0)
>> +               return ERR_PTR(-EINVAL);
>> +
>> +       list_for_each_entry(cpufreq_dev, &cooling_cpufreq_list, node)
>> +               cpufreq_dev_count++;
>> +
>> +       cpufreq_dev = kzalloc(sizeof(struct cpufreq_cooling_device),
>> +                       GFP_KERNEL);
>> +       if (!cpufreq_dev)
>> +               return ERR_PTR(-ENOMEM);
>> +
>> +       /*Verify that all the entries of freq_clip_table are present*/
>> +       for (i = 0; i < tab_size; i++) {
>> +               clip_tab = ((struct freq_clip_table *)&tab_ptr[i]);
>> +               if (!clip_tab->freq_clip_max || !clip_tab->mask_val
>> +                                       || !clip_tab->temp_level) {
>
> About  clip_tab->temp_level:
> I'd like to remove this variable checking, because as suggested by Vincent
> Guittot, it is better to separate cooling devices
> and thermal zone, thus we can add/remove cooling devices freely/dynamically.
> In such case, a cooling device doesn't
> know any temp_level before binding--the binding condition is name matching,
> what's more, the cooling device should not
> know much data of other devices.

Hi Hongbo,

The temp_level is not used anywhere inside the cooling devices. They
are just present to pass the trip temperature information to the
registered notifiers.

Thanks,
Amit D
>
>> +                       kfree(cpufreq_dev);
>> +                       return ERR_PTR(-EINVAL);
>> +               }
>> +               /*
>> +                *Consolidate all the cpumask for all the individual
>> entries
>> +                *of the trip table. This is useful in resetting all the
>> +                *clipped frequencies to the normal level for each cpufreq
>> +                *cooling device.
>> +                */
>> +               cpumask_or(&cpufreq_dev->allowed_cpus,
>> +                       &cpufreq_dev->allowed_cpus, clip_tab->mask_val);
>> +       }
>> +
>> +       cpufreq_dev->tab_ptr = tab_ptr;
>> +       cpufreq_dev->tab_size = tab_size;
>> +
>> +       ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
>> +       if (ret) {
>> +               kfree(cpufreq_dev);
>> +               return ERR_PTR(-EINVAL);
>> +       }
>> +
>> +       sprintf(dev_name, "thermal-cpufreq-%d", cpufreq_dev->id);
>> +
>> +       cool_dev = thermal_cooling_device_register(dev_name, cpufreq_dev,
>> +                                               &cpufreq_cooling_ops);
>> +       if (!cool_dev) {
>> +               release_idr(&cpufreq_idr, cpufreq_dev->id);
>> +               kfree(cpufreq_dev);
>> +               return ERR_PTR(-EINVAL);
>> +       }
>> +       cpufreq_dev->id = id;
>> +       cpufreq_dev->cool_dev = cool_dev;
>> +       mutex_lock(&cooling_cpufreq_lock);
>> +       list_add_tail(&cpufreq_dev->node, &cooling_cpufreq_list);
>> +
>> +       /*Register the notifier for first cpufreq cooling device*/
>> +       if (cpufreq_dev_count == 0)
>> +               cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
>> +                                               CPUFREQ_POLICY_NOTIFIER);
>> +
>> +       mutex_unlock(&cooling_cpufreq_lock);
>> +       return cool_dev;
>> +}
>> +EXPORT_SYMBOL(cpufreq_cooling_register);
>> +
>> +/**
>> + * cpufreq_cooling_unregister - function to remove cpufreq cooling
>> device.
>> + * @cdev: thermal cooling device pointer.
>> + */
>> +void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
>> +{
>> +       struct cpufreq_cooling_device *cpufreq_dev = NULL;
>> +       unsigned int cpufreq_dev_count = 0;
>> +
>> +       mutex_lock(&cooling_cpufreq_lock);
>> +       list_for_each_entry(cpufreq_dev, &cooling_cpufreq_list, node) {
>> +               if (cpufreq_dev && cpufreq_dev->cool_dev == cdev)
>> +                       break;
>> +               cpufreq_dev_count++;
>> +       }
>> +
>> +       if (!cpufreq_dev || cpufreq_dev->cool_dev != cdev) {
>> +               mutex_unlock(&cooling_cpufreq_lock);
>> +               return;
>> +       }
>> +
>> +       list_del(&cpufreq_dev->node);
>> +
>> +       /*Unregister the notifier for the last cpufreq cooling device*/
>> +       if (cpufreq_dev_count == 1) {
>> +
>> cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
>> +                                       CPUFREQ_POLICY_NOTIFIER);
>> +       }
>> +       mutex_unlock(&cooling_cpufreq_lock);
>> +       thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
>> +       release_idr(&cpufreq_idr, cpufreq_dev->id);
>> +       kfree(cpufreq_dev);
>> +}
>> +EXPORT_SYMBOL(cpufreq_cooling_unregister);
>> diff --git a/include/linux/cpu_cooling.h b/include/linux/cpu_cooling.h
>> new file mode 100644
>> index 0000000..ed6c096
>> --- /dev/null
>> +++ b/include/linux/cpu_cooling.h
>> @@ -0,0 +1,99 @@
>> +/*
>> + *  linux/include/linux/cpu_cooling.h
>> + *
>> + *  Copyright (C) 2012 Samsung Electronics Co.,
>> Ltd(http://www.samsung.com)
>> + *  Copyright (C) 2012  Amit Daniel <amit.kachhap@linaro.org>
>> + *
>> + *
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> + *  This program is free software; you can redistribute it and/or modify
>> + *  it under the terms of the GNU General Public License as published by
>> + *  the Free Software Foundation; version 2 of the License.
>> + *
>> + *  This program is distributed in the hope that it will be useful, but
>> + *  WITHOUT ANY WARRANTY; without even the implied warranty of
>> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>> + *  General Public License for more details.
>> + *
>> + *  You should have received a copy of the GNU General Public License
>> along
>> + *  with this program; if not, write to the Free Software Foundation,
>> Inc.,
>> + *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
>> + *
>> + *
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> + */
>> +
>> +#ifndef __CPU_COOLING_H__
>> +#define __CPU_COOLING_H__
>> +
>> +#include <linux/thermal.h>
>> +
>> +#define CPUFREQ_COOLING_START          0
>> +#define CPUFREQ_COOLING_STOP           1
>> +
>> +/**
>> + * struct freq_clip_table
>> + * @freq_clip_max: maximum frequency allowed for this cooling state.
>> + * @temp_level: Temperature level at which the temperature clipping will
>> + *     happen.
>> + * @mask_val: cpumask of the allowed cpu's where the clipping will take
>> place.
>> + *
>> + * This structure is required to be filled and passed to the
>> + * cpufreq_cooling_unregister function.
>> + */
>> +struct freq_clip_table {
>> +       unsigned int freq_clip_max;
>> +       unsigned int temp_level;
>> +       const struct cpumask *mask_val;
>> +};
>> +
>> +/**
>> + * cputherm_register_notifier - Register a notifier with cpu cooling
>> interface.
>> + * @nb:        struct notifier_block * with callback info.
>> + * @list: integer value for which notification is needed. possible values
>> are
>> + *     CPUFREQ_COOLING_TYPE and CPUHOTPLUG_COOLING_TYPE.
>> + *
>> + * This exported function registers a driver with cpu cooling layer. The
>> driver
>> + * will be notified when any cpu cooling action is called.
>> + */
>> +int cputherm_register_notifier(struct notifier_block *nb, unsigned int
>> list);
>> +
>> +/**
>> + * cputherm_unregister_notifier - Un-register a notifier.
>> + * @nb:        struct notifier_block * with callback info.
>> + * @list: integer value for which notification is needed. values possible
>> are
>> + *     CPUFREQ_COOLING_TYPE.
>> + *
>> + * This exported function un-registers a driver with cpu cooling layer.
>> + */
>> +int cputherm_unregister_notifier(struct notifier_block *nb, unsigned int
>> list);
>> +
>> +#ifdef CONFIG_CPU_FREQ
>> +/**
>> + * cpufreq_cooling_register - function to create cpufreq cooling device.
>> + * @tab_ptr: table ptr containing the maximum value of frequency to be
>> clipped
>> + *     for each cooling state.
>> + * @tab_size: count of entries in the above table.
>> + * @mask_val: cpumask containing the allowed cpu's where frequency
>> clipping can
>> + *     happen.
>> + */
>> +struct thermal_cooling_device *cpufreq_cooling_register(
>> +       struct freq_clip_table *tab_ptr, unsigned int tab_size);
>> +
>> +/**
>> + * cpufreq_cooling_unregister - function to remove cpufreq cooling
>> device.
>> + * @cdev: thermal cooling device pointer.
>> + */
>> +void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev);
>> +#else /*!CONFIG_CPU_FREQ*/
>> +static inline struct thermal_cooling_device *cpufreq_cooling_register(
>> +       struct freq_clip_table *tab_ptr, unsigned int tab_size);
>> +{
>> +       return NULL;
>> +}
>> +static inline void cpufreq_cooling_unregister(
>> +               struct thermal_cooling_device *cdev)
>> +{
>> +       return;
>> +}
>> +#endif /*CONFIG_CPU_FREQ*/
>> +
>> +#endif /* __CPU_COOLING_H__ */
>> --
>> 1.7.1
>>
>>
>> _______________________________________________
>>
>> linaro-dev mailing list
>> linaro-dev@lists.linaro.org
>> http://lists.linaro.org/mailman/listinfo/linaro-dev
>
>
>
> _______________________________________________
> linaro-dev mailing list
> linaro-dev@lists.linaro.org
> http://lists.linaro.org/mailman/listinfo/linaro-dev
>

See my codes:

http://git.linaro.org/gitweb?p=people/hongbozhang/kernel.git;a=blob;f=drivers/thermal/db8500_cpufreq_cooling.c;h=2599149c25d381d55c083d19545f11005c05fdc2;hb=ste_thermal_v3.4_rc3

http://git.linaro.org/gitweb?p=people/hongbozhang/kernel.git;a=blob;f=drivers/thermal/db8500_thermal.c;h=2bb9b9a1477732df3f786ba246cf28ebc55f9998;hb=ste_thermal_v3.4_rc3

I create cooling device separately from thermal zone, before binding the
cooling device doesn't know any trip points.
This is good for adding/removing cooling devices freely.

What's more, my driver won't work if this checking still there.

I mean, this checking is optional, not mandatory.


On 12 July 2012 11:20, amit kachhap <amit.kachhap@linaro.org> wrote:

> On Tue, Jul 10, 2012 at 12:31 PM, Hongbo Zhang <hongbo.zhang@linaro.org>
> wrote:
> >
> >
> > On 12 May 2012 17:40, Amit Daniel Kachhap <amit.kachhap@linaro.org>
> wrote:
> >>
> >> This patch adds support for generic cpu thermal cooling low level
> >> implementations using frequency scaling up/down based on the
> registration
> >> parameters. Different cpu related cooling devices can be registered by
> the
> >> user and the binding of these cooling devices to the corresponding
> >> trip points can be easily done as the registration APIs return the
> >> cooling device pointer. The user of these APIs are responsible for
> >> passing clipping frequency . The drivers can also register to recieve
> >> notification about any cooling action called.
> >>
> >> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@linaro.org>
> >> ---
> >>  Documentation/thermal/cpu-cooling-api.txt |   60 ++++
> >>  drivers/thermal/Kconfig                   |   11 +
> >>  drivers/thermal/Makefile                  |    3 +-
> >>  drivers/thermal/cpu_cooling.c             |  483
> >> +++++++++++++++++++++++++++++
> >>  include/linux/cpu_cooling.h               |   99 ++++++
> >>  5 files changed, 655 insertions(+), 1 deletions(-)
> >>  create mode 100644 Documentation/thermal/cpu-cooling-api.txt
> >>  create mode 100644 drivers/thermal/cpu_cooling.c
> >>  create mode 100644 include/linux/cpu_cooling.h
> >>
> >> diff --git a/Documentation/thermal/cpu-cooling-api.txt
> >> b/Documentation/thermal/cpu-cooling-api.txt
> >> new file mode 100644
> >> index 0000000..557adb8
> >> --- /dev/null
> >> +++ b/Documentation/thermal/cpu-cooling-api.txt
> >> @@ -0,0 +1,60 @@
> >> +CPU cooling APIs How To
> >> +===================================
> >> +
> >> +Written by Amit Daniel Kachhap <amit.kachhap@linaro.org>
> >> +
> >> +Updated: 12 May 2012
> >> +
> >> +Copyright (c)  2012 Samsung Electronics Co., Ltd(
> http://www.samsung.com)
> >> +
> >> +0. Introduction
> >> +
> >> +The generic cpu cooling(freq clipping, cpuhotplug etc) provides
> >> +registration/unregistration APIs to the caller. The binding of the
> >> cooling
> >> +devices to the trip point is left for the user. The registration APIs
> >> returns
> >> +the cooling device pointer.
> >> +
> >> +1. cpu cooling APIs
> >> +
> >> +1.1 cpufreq registration/unregistration APIs
> >> +1.1.1 struct thermal_cooling_device *cpufreq_cooling_register(
> >> +       struct freq_clip_table *tab_ptr, unsigned int tab_size)
> >> +
> >> +    This interface function registers the cpufreq cooling device with
> the
> >> name
> >> +    "thermal-cpufreq-%x". This api can support multiple instances of
> >> cpufreq
> >> +    cooling devices.
> >> +
> >> +    tab_ptr: The table containing the maximum value of frequency to be
> >> clipped
> >> +    for each cooling state.
> >> +       .freq_clip_max: Value of frequency to be clipped for each
> allowed
> >> +        cpus.
> >> +       .temp_level: Temperature level at which the frequency clamping
> >> will
> >> +       happen.
> >> +       .mask_val: cpumask of the allowed cpu's
> >> +    tab_size: the total number of cpufreq cooling states.
> >> +
> >> +1.1.2 void cpufreq_cooling_unregister(struct thermal_cooling_device
> >> *cdev)
> >> +
> >> +    This interface function unregisters the "thermal-cpufreq-%x"
> cooling
> >> device.
> >> +
> >> +    cdev: Cooling device pointer which has to be unregistered.
> >> +
> >> +
> >> +1.2 CPU cooling action notifier register/unregister interface
> >> +1.2.1 int cputherm_register_notifier(struct notifier_block *nb,
> >> +       unsigned int list)
> >> +
> >> +    This interface registers a driver with cpu cooling layer. The
> driver
> >> will
> >> +    be notified when any cpu cooling action is called.
> >> +
> >> +    nb: notifier function to register
> >> +    list: CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP
> >> +
> >> +1.2.2 int cputherm_unregister_notifier(struct notifier_block *nb,
> >> +       unsigned int list)
> >> +
> >> +    This interface registers a driver with cpu cooling layer. The
> driver
> >> will
> >> +    be notified when any cpu cooling action is called.
> >> +
> >> +    nb: notifier function to register
> >> +    list: CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP
> >> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
> >> index 514a691..d9c529f 100644
> >> --- a/drivers/thermal/Kconfig
> >> +++ b/drivers/thermal/Kconfig
> >> @@ -19,6 +19,17 @@ config THERMAL_HWMON
> >>         depends on HWMON=y || HWMON=THERMAL
> >>         default y
> >>
> >> +config CPU_THERMAL
> >> +       bool "generic cpu cooling support"
> >> +       depends on THERMAL && CPU_FREQ
> >> +       help
> >> +         This implements the generic cpu cooling mechanism through
> >> frequency
> >> +         reduction, cpu hotplug and any other ways of reducing
> >> temperature. An
> >> +         ACPI version of this already
> >> exists(drivers/acpi/processor_thermal.c).
> >> +         This will be useful for platforms using the generic thermal
> >> interface
> >> +         and not the ACPI interface.
> >> +         If you want this support, you should say Y or M here.
> >> +
> >>  config SPEAR_THERMAL
> >>         bool "SPEAr thermal sensor driver"
> >>         depends on THERMAL
> >> diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
> >> index a9fff0b..30c456c 100644
> >> --- a/drivers/thermal/Makefile
> >> +++ b/drivers/thermal/Makefile
> >> @@ -3,4 +3,5 @@
> >>  #
> >>
> >>  obj-$(CONFIG_THERMAL)          += thermal_sys.o
> >> -obj-$(CONFIG_SPEAR_THERMAL)            += spear_thermal.o
> >> \ No newline at end of file
> >> +obj-$(CONFIG_CPU_THERMAL)       += cpu_cooling.o
> >> +obj-$(CONFIG_SPEAR_THERMAL)            += spear_thermal.o
> >> diff --git a/drivers/thermal/cpu_cooling.c
> b/drivers/thermal/cpu_cooling.c
> >> new file mode 100644
> >> index 0000000..c40d9a0
> >> --- /dev/null
> >> +++ b/drivers/thermal/cpu_cooling.c
> >> @@ -0,0 +1,483 @@
> >> +/*
> >> + *  linux/drivers/thermal/cpu_cooling.c
> >> + *
> >> + *  Copyright (C) 2012 Samsung Electronics Co.,
> >> Ltd(http://www.samsung.com)
> >> + *  Copyright (C) 2012  Amit Daniel <amit.kachhap@linaro.org>
> >> + *
> >> + *
> >>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >> + *  This program is free software; you can redistribute it and/or
> modify
> >> + *  it under the terms of the GNU General Public License as published
> by
> >> + *  the Free Software Foundation; version 2 of the License.
> >> + *
> >> + *  This program is distributed in the hope that it will be useful, but
> >> + *  WITHOUT ANY WARRANTY; without even the implied warranty of
> >> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> >> + *  General Public License for more details.
> >> + *
> >> + *  You should have received a copy of the GNU General Public License
> >> along
> >> + *  with this program; if not, write to the Free Software Foundation,
> >> Inc.,
> >> + *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
> >> + *
> >> + *
> >>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >> + */
> >> +#include <linux/kernel.h>
> >> +#include <linux/module.h>
> >> +#include <linux/thermal.h>
> >> +#include <linux/platform_device.h>
> >> +#include <linux/cpufreq.h>
> >> +#include <linux/err.h>
> >> +#include <linux/slab.h>
> >> +#include <linux/cpu.h>
> >> +#include <linux/cpu_cooling.h>
> >> +
> >> +/**
> >> + * struct cpufreq_cooling_device
> >> + * @id: unique integer value corresponding to each
> cpufreq_cooling_device
> >> + *     registered.
> >> + * @cool_dev: thermal_cooling_device pointer to keep track of the the
> >> + *     egistered cooling device.
> >> + * @tab_ptr: freq_clip_table table containing the maximum value of
> >> frequency to
> >> + *     be set for different cooling state.
> >> + * @tab_size: integer value representing a count of the above table.
> >> + * @cpufreq_state: integer value representing the current state of
> >> cpufreq
> >> + *     cooling devices.
> >> + * @allowed_cpus: all the cpus involved for this
> cpufreq_cooling_device.
> >> + * @node: list_head to link all cpufreq_cooling_device together.
> >> + *
> >> + * This structure is required for keeping information of each
> >> + * cpufreq_cooling_device registered as a list whose head is
> represented
> >> by
> >> + * cooling_cpufreq_list. In order to prevent corruption of this list a
> >> + * mutex lock cooling_cpufreq_lock is used.
> >> + */
> >> +struct cpufreq_cooling_device {
> >> +       int id;
> >> +       struct thermal_cooling_device *cool_dev;
> >> +       struct freq_clip_table *tab_ptr;
> >> +       unsigned int tab_size;
> >> +       unsigned int cpufreq_state;
> >> +       struct cpumask allowed_cpus;
> >> +       struct list_head node;
> >> +};
> >> +static LIST_HEAD(cooling_cpufreq_list);
> >> +static DEFINE_MUTEX(cooling_cpufreq_lock);
> >> +static DEFINE_IDR(cpufreq_idr);
> >> +
> >> +/*per cpu variable to store the previous max frequency allowed*/
> >> +static DEFINE_PER_CPU(unsigned int, max_policy_freq);
> >> +
> >> +/*notify_table passes value to the CPUFREQ_ADJUST callback function.*/
> >> +#define NOTIFY_INVALID NULL
> >> +static struct freq_clip_table *notify_table;
> >> +
> >> +/*Head of the blocking notifier chain to inform about frequency
> >> clamping*/
> >> +static BLOCKING_NOTIFIER_HEAD(cputherm_state_notifier_list);
> >> +
> >> +/**
> >> + * get_idr - function to get a unique id.
> >> + * @idr: struct idr * handle used to create a id.
> >> + * @id: int * value generated by this function.
> >> + */
> >> +static int get_idr(struct idr *idr, int *id)
> >> +{
> >> +       int err;
> >> +again:
> >> +       if (unlikely(idr_pre_get(idr, GFP_KERNEL) == 0))
> >> +               return -ENOMEM;
> >> +
> >> +       mutex_lock(&cooling_cpufreq_lock);
> >> +       err = idr_get_new(idr, NULL, id);
> >> +       mutex_unlock(&cooling_cpufreq_lock);
> >> +
> >> +       if (unlikely(err == -EAGAIN))
> >> +               goto again;
> >> +       else if (unlikely(err))
> >> +               return err;
> >> +
> >> +       *id = *id & MAX_ID_MASK;
> >> +       return 0;
> >> +}
> >> +
> >> +/**
> >> + * release_idr - function to free the unique id.
> >> + * @idr: struct idr * handle used for creating the id.
> >> + * @id: int value representing the unique id.
> >> + */
> >> +static void release_idr(struct idr *idr, int id)
> >> +{
> >> +       mutex_lock(&cooling_cpufreq_lock);
> >> +       idr_remove(idr, id);
> >> +       mutex_unlock(&cooling_cpufreq_lock);
> >> +}
> >> +
> >> +/**
> >> + * cputherm_register_notifier - Register a notifier with cpu cooling
> >> interface.
> >> + * @nb:        struct notifier_block * with callback info.
> >> + * @list: integer value for which notification is needed. possible
> values
> >> are
> >> + *     CPUFREQ_COOLING_START and CPUFREQ_COOLING_STOP.
> >> + *
> >> + * This exported function registers a driver with cpu cooling layer.
> The
> >> driver
> >> + * will be notified when any cpu cooling action is called.
> >> + */
> >> +int cputherm_register_notifier(struct notifier_block *nb, unsigned int
> >> list)
> >> +{
> >> +       int ret = 0;
> >> +
> >> +       switch (list) {
> >> +       case CPUFREQ_COOLING_START:
> >> +       case CPUFREQ_COOLING_STOP:
> >> +               ret = blocking_notifier_chain_register(
> >> +                               &cputherm_state_notifier_list, nb);
> >> +               break;
> >> +       default:
> >> +               ret = -EINVAL;
> >> +       }
> >> +       return ret;
> >> +}
> >> +EXPORT_SYMBOL(cputherm_register_notifier);
> >> +
> >> +/**
> >> + * cputherm_unregister_notifier - Un-register a notifier.
> >> + * @nb:        struct notifier_block * with callback info.
> >> + * @list: integer value for which notification is needed. values
> possible
> >> are
> >> + *     CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP.
> >> + *
> >> + * This exported function un-registers a driver with cpu cooling layer.
> >> + */
> >> +int cputherm_unregister_notifier(struct notifier_block *nb, unsigned
> int
> >> list)
> >> +{
> >> +       int ret = 0;
> >> +
> >> +       switch (list) {
> >> +       case CPUFREQ_COOLING_START:
> >> +       case CPUFREQ_COOLING_STOP:
> >> +               ret = blocking_notifier_chain_unregister(
> >> +                               &cputherm_state_notifier_list, nb);
> >> +               break;
> >> +       default:
> >> +               ret = -EINVAL;
> >> +       }
> >> +       return ret;
> >> +}
> >> +EXPORT_SYMBOL(cputherm_unregister_notifier);
> >> +
> >> +/*Below codes defines functions to be used for cpufreq as cooling
> >> device*/
> >> +
> >> +/**
> >> + * is_cpufreq_valid - function to check if a cpu has frequency
> transition
> >> policy.
> >> + * @cpu: cpu for which check is needed.
> >> + */
> >> +static int is_cpufreq_valid(int cpu)
> >> +{
> >> +       struct cpufreq_policy policy;
> >> +       return !cpufreq_get_policy(&policy, cpu);
> >> +}
> >> +
> >> +/**
> >> + * cpufreq_apply_cooling - function to apply frequency clipping.
> >> + * @cpufreq_device: cpufreq_cooling_device pointer containing frequency
> >> + *     clipping data.
> >> + * @cooling_state: value of the cooling state.
> >> + */
> >> +static int cpufreq_apply_cooling(struct cpufreq_cooling_device
> >> *cpufreq_device,
> >> +                               unsigned long cooling_state)
> >> +{
> >> +       unsigned int event, cpuid, state;
> >> +       struct freq_clip_table *th_table, *table_ptr;
> >> +       const struct cpumask *maskPtr = &cpufreq_device->allowed_cpus;
> >> +       struct cpufreq_cooling_device *cpufreq_ptr;
> >> +
> >> +       if (cooling_state > cpufreq_device->tab_size)
> >> +               return -EINVAL;
> >> +
> >> +       /*Check if the old cooling action is same as new cooling
> action*/
> >> +       if (cpufreq_device->cpufreq_state == cooling_state)
> >> +               return 0;
> >> +
> >> +       /*pass cooling table info to the cpufreq_thermal_notifier
> >> callback*/
> >> +       notify_table = NOTIFY_INVALID;
> >> +
> >> +       if (cooling_state > 0) {
> >> +               th_table = &(cpufreq_device->tab_ptr[cooling_state -
> 1]);
> >> +               notify_table = th_table;
> >> +       }
> >> +
> >> +       /*check if any lower clip frequency active in other
> >> cpufreq_device's*/
> >> +       list_for_each_entry(cpufreq_ptr, &cooling_cpufreq_list, node) {
> >> +
> >> +               state = cpufreq_ptr->cpufreq_state;
> >> +               if (state == 0 || cpufreq_ptr == cpufreq_device)
> >> +                       continue;
> >> +
> >> +               if (!cpumask_equal(&cpufreq_ptr->allowed_cpus,
> >> +                               &cpufreq_device->allowed_cpus))
> >> +                       continue;
> >> +
> >> +               table_ptr = &(cpufreq_ptr->tab_ptr[state - 1]);
> >> +               if (notify_table == NULL ||
> >> +                               (table_ptr->freq_clip_max <
> >> +                               notify_table->freq_clip_max))
> >> +                       notify_table =  table_ptr;
> >> +       }
> >> +
> >> +       cpufreq_device->cpufreq_state = cooling_state;
> >> +
> >> +       if (notify_table != NOTIFY_INVALID) {
> >> +               event = CPUFREQ_COOLING_START;
> >> +               maskPtr = notify_table->mask_val;
> >> +       } else {
> >> +               event = CPUFREQ_COOLING_STOP;
> >> +       }
> >> +
> >> +       blocking_notifier_call_chain(&cputherm_state_notifier_list,
> >> +                                               event, notify_table);
> >> +
> >> +       for_each_cpu(cpuid, maskPtr) {
> >> +               if (is_cpufreq_valid(cpuid))
> >> +                       cpufreq_update_policy(cpuid);
> >> +       }
> >> +
> >> +       notify_table = NOTIFY_INVALID;
> >> +
> >> +       return 0;
> >> +}
> >> +
> >> +/**
> >> + * cpufreq_thermal_notifier - notifier callback for cpufreq policy
> >> change.
> >> + * @nb:        struct notifier_block * with callback info.
> >> + * @event: value showing cpufreq event for which this function invoked.
> >> + * @data: callback-specific data
> >> + */
> >> +static int cpufreq_thermal_notifier(struct notifier_block *nb,
> >> +                                       unsigned long event, void *data)
> >> +{
> >> +       struct cpufreq_policy *policy = data;
> >> +       unsigned long max_freq = 0;
> >> +
> >> +       if (event != CPUFREQ_ADJUST)
> >> +               return 0;
> >> +
> >> +       if (notify_table != NOTIFY_INVALID) {
> >> +               max_freq = notify_table->freq_clip_max;
> >> +
> >> +               if (!per_cpu(max_policy_freq, policy->cpu))
> >> +                       per_cpu(max_policy_freq, policy->cpu) =
> >> policy->max;
> >> +       } else {
> >> +               if (per_cpu(max_policy_freq, policy->cpu)) {
> >> +                       max_freq = per_cpu(max_policy_freq,
> policy->cpu);
> >> +                       per_cpu(max_policy_freq, policy->cpu) = 0;
> >> +               } else {
> >> +                       max_freq = policy->max;
> >> +               }
> >> +       }
> >> +
> >> +       /* Never exceed user_policy.max*/
> >> +       if (max_freq > policy->user_policy.max)
> >> +               max_freq = policy->user_policy.max;
> >> +
> >> +       if (policy->max != max_freq)
> >> +               cpufreq_verify_within_limits(policy, 0, max_freq);
> >> +
> >> +       return 0;
> >> +}
> >> +
> >> +/*
> >> + * cpufreq cooling device callback functions are defined below
> >> + */
> >> +
> >> +/**
> >> + * cpufreq_get_max_state - callback function to get the max cooling
> >> state.
> >> + * @cdev: thermal cooling device pointer.
> >> + * @state: fill this variable with the max cooling state.
> >> + */
> >> +static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
> >> +                                unsigned long *state)
> >> +{
> >> +       int ret = -EINVAL;
> >> +       struct cpufreq_cooling_device *cpufreq_device;
> >> +
> >> +       mutex_lock(&cooling_cpufreq_lock);
> >> +       list_for_each_entry(cpufreq_device, &cooling_cpufreq_list,
> node) {
> >> +               if (cpufreq_device && cpufreq_device->cool_dev == cdev)
> {
> >> +                       *state = cpufreq_device->tab_size;
> >> +                       ret = 0;
> >> +                       break;
> >> +               }
> >> +       }
> >> +       mutex_unlock(&cooling_cpufreq_lock);
> >> +       return ret;
> >> +}
> >> +
> >> +/**
> >> + * cpufreq_get_cur_state - callback function to get the current cooling
> >> state.
> >> + * @cdev: thermal cooling device pointer.
> >> + * @state: fill this variable with the current cooling state.
> >> + */
> >> +static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
> >> +                                unsigned long *state)
> >> +{
> >> +       int ret = -EINVAL;
> >> +       struct cpufreq_cooling_device *cpufreq_device;
> >> +
> >> +       mutex_lock(&cooling_cpufreq_lock);
> >> +       list_for_each_entry(cpufreq_device, &cooling_cpufreq_list,
> node) {
> >> +               if (cpufreq_device && cpufreq_device->cool_dev == cdev)
> {
> >> +                       *state = cpufreq_device->cpufreq_state;
> >> +                       ret = 0;
> >> +                       break;
> >> +               }
> >> +       }
> >> +       mutex_unlock(&cooling_cpufreq_lock);
> >> +       return ret;
> >> +}
> >> +
> >> +/**
> >> + * cpufreq_set_cur_state - callback function to set the current cooling
> >> state.
> >> + * @cdev: thermal cooling device pointer.
> >> + * @state: set this variable to the current cooling state.
> >> + */
> >> +static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
> >> +                                unsigned long state)
> >> +{
> >> +       int ret = -EINVAL;
> >> +       struct cpufreq_cooling_device *cpufreq_device;
> >> +
> >> +       mutex_lock(&cooling_cpufreq_lock);
> >> +       list_for_each_entry(cpufreq_device, &cooling_cpufreq_list,
> node) {
> >> +               if (cpufreq_device && cpufreq_device->cool_dev == cdev)
> {
> >> +                       ret = 0;
> >> +                       break;
> >> +               }
> >> +       }
> >> +       if (!ret)
> >> +               ret = cpufreq_apply_cooling(cpufreq_device, state);
> >> +
> >> +       mutex_unlock(&cooling_cpufreq_lock);
> >> +
> >> +       return ret;
> >> +}
> >> +
> >> +/*Bind cpufreq callbacks to thermal cooling device ops*/
> >> +static struct thermal_cooling_device_ops const cpufreq_cooling_ops = {
> >> +       .get_max_state = cpufreq_get_max_state,
> >> +       .get_cur_state = cpufreq_get_cur_state,
> >> +       .set_cur_state = cpufreq_set_cur_state,
> >> +};
> >> +
> >> +/*Notifier for cpufreq policy change*/
> >> +static struct notifier_block thermal_cpufreq_notifier_block = {
> >> +       .notifier_call = cpufreq_thermal_notifier,
> >> +};
> >> +
> >> +/**
> >> + * cpufreq_cooling_register - function to create cpufreq cooling
> device.
> >> + * @tab_ptr: table ptr containing the maximum value of frequency to be
> >> clipped
> >> + *     for each cooling state.
> >> + * @tab_size: count of entries in the above table.
> >> + *     happen.
> >> + */
> >> +struct thermal_cooling_device *cpufreq_cooling_register(
> >> +       struct freq_clip_table *tab_ptr, unsigned int tab_size)
> >> +{
> >> +       struct thermal_cooling_device *cool_dev;
> >> +       struct cpufreq_cooling_device *cpufreq_dev = NULL;
> >> +       struct freq_clip_table *clip_tab;
> >> +       unsigned int cpufreq_dev_count = 0;
> >> +       char dev_name[THERMAL_NAME_LENGTH];
> >> +       int ret = 0, id = 0, i;
> >> +
> >> +       if (tab_ptr == NULL || tab_size == 0)
> >> +               return ERR_PTR(-EINVAL);
> >> +
> >> +       list_for_each_entry(cpufreq_dev, &cooling_cpufreq_list, node)
> >> +               cpufreq_dev_count++;
> >> +
> >> +       cpufreq_dev = kzalloc(sizeof(struct cpufreq_cooling_device),
> >> +                       GFP_KERNEL);
> >> +       if (!cpufreq_dev)
> >> +               return ERR_PTR(-ENOMEM);
> >> +
> >> +       /*Verify that all the entries of freq_clip_table are present*/
> >> +       for (i = 0; i < tab_size; i++) {
> >> +               clip_tab = ((struct freq_clip_table *)&tab_ptr[i]);
> >> +               if (!clip_tab->freq_clip_max || !clip_tab->mask_val
> >> +                                       || !clip_tab->temp_level) {
> >
> > About  clip_tab->temp_level:
> > I'd like to remove this variable checking, because as suggested by
> Vincent
> > Guittot, it is better to separate cooling devices
> > and thermal zone, thus we can add/remove cooling devices
> freely/dynamically.
> > In such case, a cooling device doesn't
> > know any temp_level before binding--the binding condition is name
> matching,
> > what's more, the cooling device should not
> > know much data of other devices.
>
> Hi Hongbo,
>
> The temp_level is not used anywhere inside the cooling devices. They
> are just present to pass the trip temperature information to the
> registered notifiers.
>
> Thanks,
> Amit D
> >
> >> +                       kfree(cpufreq_dev);
> >> +                       return ERR_PTR(-EINVAL);
> >> +               }
> >> +               /*
> >> +                *Consolidate all the cpumask for all the individual
> >> entries
> >> +                *of the trip table. This is useful in resetting all the
> >> +                *clipped frequencies to the normal level for each
> cpufreq
> >> +                *cooling device.
> >> +                */
> >> +               cpumask_or(&cpufreq_dev->allowed_cpus,
> >> +                       &cpufreq_dev->allowed_cpus, clip_tab->mask_val);
> >> +       }
> >> +
> >> +       cpufreq_dev->tab_ptr = tab_ptr;
> >> +       cpufreq_dev->tab_size = tab_size;
> >> +
> >> +       ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
> >> +       if (ret) {
> >> +               kfree(cpufreq_dev);
> >> +               return ERR_PTR(-EINVAL);
> >> +       }
> >> +
> >> +       sprintf(dev_name, "thermal-cpufreq-%d", cpufreq_dev->id);
> >> +
> >> +       cool_dev = thermal_cooling_device_register(dev_name,
> cpufreq_dev,
> >> +                                               &cpufreq_cooling_ops);
> >> +       if (!cool_dev) {
> >> +               release_idr(&cpufreq_idr, cpufreq_dev->id);
> >> +               kfree(cpufreq_dev);
> >> +               return ERR_PTR(-EINVAL);
> >> +       }
> >> +       cpufreq_dev->id = id;
> >> +       cpufreq_dev->cool_dev = cool_dev;
> >> +       mutex_lock(&cooling_cpufreq_lock);
> >> +       list_add_tail(&cpufreq_dev->node, &cooling_cpufreq_list);
> >> +
> >> +       /*Register the notifier for first cpufreq cooling device*/
> >> +       if (cpufreq_dev_count == 0)
> >> +
> cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
> >> +
> CPUFREQ_POLICY_NOTIFIER);
> >> +
> >> +       mutex_unlock(&cooling_cpufreq_lock);
> >> +       return cool_dev;
> >> +}
> >> +EXPORT_SYMBOL(cpufreq_cooling_register);
> >> +
> >> +/**
> >> + * cpufreq_cooling_unregister - function to remove cpufreq cooling
> >> device.
> >> + * @cdev: thermal cooling device pointer.
> >> + */
> >> +void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
> >> +{
> >> +       struct cpufreq_cooling_device *cpufreq_dev = NULL;
> >> +       unsigned int cpufreq_dev_count = 0;
> >> +
> >> +       mutex_lock(&cooling_cpufreq_lock);
> >> +       list_for_each_entry(cpufreq_dev, &cooling_cpufreq_list, node) {
> >> +               if (cpufreq_dev && cpufreq_dev->cool_dev == cdev)
> >> +                       break;
> >> +               cpufreq_dev_count++;
> >> +       }
> >> +
> >> +       if (!cpufreq_dev || cpufreq_dev->cool_dev != cdev) {
> >> +               mutex_unlock(&cooling_cpufreq_lock);
> >> +               return;
> >> +       }
> >> +
> >> +       list_del(&cpufreq_dev->node);
> >> +
> >> +       /*Unregister the notifier for the last cpufreq cooling device*/
> >> +       if (cpufreq_dev_count == 1) {
> >> +
> >> cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
> >> +                                       CPUFREQ_POLICY_NOTIFIER);
> >> +       }
> >> +       mutex_unlock(&cooling_cpufreq_lock);
> >> +       thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
> >> +       release_idr(&cpufreq_idr, cpufreq_dev->id);
> >> +       kfree(cpufreq_dev);
> >> +}
> >> +EXPORT_SYMBOL(cpufreq_cooling_unregister);
> >> diff --git a/include/linux/cpu_cooling.h b/include/linux/cpu_cooling.h
> >> new file mode 100644
> >> index 0000000..ed6c096
> >> --- /dev/null
> >> +++ b/include/linux/cpu_cooling.h
> >> @@ -0,0 +1,99 @@
> >> +/*
> >> + *  linux/include/linux/cpu_cooling.h
> >> + *
> >> + *  Copyright (C) 2012 Samsung Electronics Co.,
> >> Ltd(http://www.samsung.com)
> >> + *  Copyright (C) 2012  Amit Daniel <amit.kachhap@linaro.org>
> >> + *
> >> + *
> >>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >> + *  This program is free software; you can redistribute it and/or
> modify
> >> + *  it under the terms of the GNU General Public License as published
> by
> >> + *  the Free Software Foundation; version 2 of the License.
> >> + *
> >> + *  This program is distributed in the hope that it will be useful, but
> >> + *  WITHOUT ANY WARRANTY; without even the implied warranty of
> >> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> >> + *  General Public License for more details.
> >> + *
> >> + *  You should have received a copy of the GNU General Public License
> >> along
> >> + *  with this program; if not, write to the Free Software Foundation,
> >> Inc.,
> >> + *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
> >> + *
> >> + *
> >>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >> + */
> >> +
> >> +#ifndef __CPU_COOLING_H__
> >> +#define __CPU_COOLING_H__
> >> +
> >> +#include <linux/thermal.h>
> >> +
> >> +#define CPUFREQ_COOLING_START          0
> >> +#define CPUFREQ_COOLING_STOP           1
> >> +
> >> +/**
> >> + * struct freq_clip_table
> >> + * @freq_clip_max: maximum frequency allowed for this cooling state.
> >> + * @temp_level: Temperature level at which the temperature clipping
> will
> >> + *     happen.
> >> + * @mask_val: cpumask of the allowed cpu's where the clipping will take
> >> place.
> >> + *
> >> + * This structure is required to be filled and passed to the
> >> + * cpufreq_cooling_unregister function.
> >> + */
> >> +struct freq_clip_table {
> >> +       unsigned int freq_clip_max;
> >> +       unsigned int temp_level;
> >> +       const struct cpumask *mask_val;
> >> +};
> >> +
> >> +/**
> >> + * cputherm_register_notifier - Register a notifier with cpu cooling
> >> interface.
> >> + * @nb:        struct notifier_block * with callback info.
> >> + * @list: integer value for which notification is needed. possible
> values
> >> are
> >> + *     CPUFREQ_COOLING_TYPE and CPUHOTPLUG_COOLING_TYPE.
> >> + *
> >> + * This exported function registers a driver with cpu cooling layer.
> The
> >> driver
> >> + * will be notified when any cpu cooling action is called.
> >> + */
> >> +int cputherm_register_notifier(struct notifier_block *nb, unsigned int
> >> list);
> >> +
> >> +/**
> >> + * cputherm_unregister_notifier - Un-register a notifier.
> >> + * @nb:        struct notifier_block * with callback info.
> >> + * @list: integer value for which notification is needed. values
> possible
> >> are
> >> + *     CPUFREQ_COOLING_TYPE.
> >> + *
> >> + * This exported function un-registers a driver with cpu cooling layer.
> >> + */
> >> +int cputherm_unregister_notifier(struct notifier_block *nb, unsigned
> int
> >> list);
> >> +
> >> +#ifdef CONFIG_CPU_FREQ
> >> +/**
> >> + * cpufreq_cooling_register - function to create cpufreq cooling
> device.
> >> + * @tab_ptr: table ptr containing the maximum value of frequency to be
> >> clipped
> >> + *     for each cooling state.
> >> + * @tab_size: count of entries in the above table.
> >> + * @mask_val: cpumask containing the allowed cpu's where frequency
> >> clipping can
> >> + *     happen.
> >> + */
> >> +struct thermal_cooling_device *cpufreq_cooling_register(
> >> +       struct freq_clip_table *tab_ptr, unsigned int tab_size);
> >> +
> >> +/**
> >> + * cpufreq_cooling_unregister - function to remove cpufreq cooling
> >> device.
> >> + * @cdev: thermal cooling device pointer.
> >> + */
> >> +void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev);
> >> +#else /*!CONFIG_CPU_FREQ*/
> >> +static inline struct thermal_cooling_device *cpufreq_cooling_register(
> >> +       struct freq_clip_table *tab_ptr, unsigned int tab_size);
> >> +{
> >> +       return NULL;
> >> +}
> >> +static inline void cpufreq_cooling_unregister(
> >> +               struct thermal_cooling_device *cdev)
> >> +{
> >> +       return;
> >> +}
> >> +#endif /*CONFIG_CPU_FREQ*/
> >> +
> >> +#endif /* __CPU_COOLING_H__ */
> >> --
> >> 1.7.1
> >>
> >>
> >> _______________________________________________
> >>
> >> linaro-dev mailing list
> >> linaro-dev@lists.linaro.org
> >> http://lists.linaro.org/mailman/listinfo/linaro-dev
> >
> >
> >
> > _______________________________________________
> > linaro-dev mailing list
> > linaro-dev@lists.linaro.org
> > http://lists.linaro.org/mailman/listinfo/linaro-dev
> >
>

On 12 May 2012 17:40, Amit Daniel Kachhap <amit.kachhap@linaro.org> wrote:

> This patch adds support for generic cpu thermal cooling low level
> implementations using frequency scaling up/down based on the registration
> parameters. Different cpu related cooling devices can be registered by the
> user and the binding of these cooling devices to the corresponding
> trip points can be easily done as the registration APIs return the
> cooling device pointer. The user of these APIs are responsible for
> passing clipping frequency . The drivers can also register to recieve
> notification about any cooling action called.
>
> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@linaro.org>
> ---
>  Documentation/thermal/cpu-cooling-api.txt |   60 ++++
>  drivers/thermal/Kconfig                   |   11 +
>  drivers/thermal/Makefile                  |    3 +-
>  drivers/thermal/cpu_cooling.c             |  483
> +++++++++++++++++++++++++++++
>  include/linux/cpu_cooling.h               |   99 ++++++
>  5 files changed, 655 insertions(+), 1 deletions(-)
>  create mode 100644 Documentation/thermal/cpu-cooling-api.txt
>  create mode 100644 drivers/thermal/cpu_cooling.c
>  create mode 100644 include/linux/cpu_cooling.h
>
> diff --git a/Documentation/thermal/cpu-cooling-api.txt
> b/Documentation/thermal/cpu-cooling-api.txt
> new file mode 100644
> index 0000000..557adb8
> --- /dev/null
> +++ b/Documentation/thermal/cpu-cooling-api.txt
> @@ -0,0 +1,60 @@
> +CPU cooling APIs How To
> +===================================
> +
> +Written by Amit Daniel Kachhap <amit.kachhap@linaro.org>
> +
> +Updated: 12 May 2012
> +
> +Copyright (c)  2012 Samsung Electronics Co., Ltd(http://www.samsung.com)
> +
> +0. Introduction
> +
> +The generic cpu cooling(freq clipping, cpuhotplug etc) provides
> +registration/unregistration APIs to the caller. The binding of the cooling
> +devices to the trip point is left for the user. The registration APIs
> returns
> +the cooling device pointer.
> +
> +1. cpu cooling APIs
> +
> +1.1 cpufreq registration/unregistration APIs
> +1.1.1 struct thermal_cooling_device *cpufreq_cooling_register(
> +       struct freq_clip_table *tab_ptr, unsigned int tab_size)
> +
> +    This interface function registers the cpufreq cooling device with the
> name
> +    "thermal-cpufreq-%x". This api can support multiple instances of
> cpufreq
> +    cooling devices.
> +
> +    tab_ptr: The table containing the maximum value of frequency to be
> clipped
> +    for each cooling state.
> +       .freq_clip_max: Value of frequency to be clipped for each allowed
> +        cpus.
> +       .temp_level: Temperature level at which the frequency clamping will
> +       happen.
> +       .mask_val: cpumask of the allowed cpu's
> +    tab_size: the total number of cpufreq cooling states.
> +
> +1.1.2 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
> +
> +    This interface function unregisters the "thermal-cpufreq-%x" cooling
> device.
> +
> +    cdev: Cooling device pointer which has to be unregistered.
> +
> +
> +1.2 CPU cooling action notifier register/unregister interface
> +1.2.1 int cputherm_register_notifier(struct notifier_block *nb,
> +       unsigned int list)
> +
> +    This interface registers a driver with cpu cooling layer. The driver
> will
> +    be notified when any cpu cooling action is called.
> +
> +    nb: notifier function to register
> +    list: CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP
> +
> +1.2.2 int cputherm_unregister_notifier(struct notifier_block *nb,
> +       unsigned int list)
> +
> +    This interface registers a driver with cpu cooling layer. The driver
> will
> +    be notified when any cpu cooling action is called.
> +
> +    nb: notifier function to register
> +    list: CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP
> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
> index 514a691..d9c529f 100644
> --- a/drivers/thermal/Kconfig
> +++ b/drivers/thermal/Kconfig
> @@ -19,6 +19,17 @@ config THERMAL_HWMON
>         depends on HWMON=y || HWMON=THERMAL
>         default y
>
> +config CPU_THERMAL
> +       bool "generic cpu cooling support"
> +       depends on THERMAL && CPU_FREQ
> +       help
> +         This implements the generic cpu cooling mechanism through
> frequency
> +         reduction, cpu hotplug and any other ways of reducing
> temperature. An
> +         ACPI version of this already
> exists(drivers/acpi/processor_thermal.c).
> +         This will be useful for platforms using the generic thermal
> interface
> +         and not the ACPI interface.
> +         If you want this support, you should say Y or M here.
>
No M value for bool item, should be N ?

> +
>  config SPEAR_THERMAL
>         bool "SPEAr thermal sensor driver"
>         depends on THERMAL
> diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
> index a9fff0b..30c456c 100644
> --- a/drivers/thermal/Makefile
> +++ b/drivers/thermal/Makefile
> @@ -3,4 +3,5 @@
>  #
>
>  obj-$(CONFIG_THERMAL)          += thermal_sys.o
> -obj-$(CONFIG_SPEAR_THERMAL)            += spear_thermal.o
> \ No newline at end of file
> +obj-$(CONFIG_CPU_THERMAL)       += cpu_cooling.o
> +obj-$(CONFIG_SPEAR_THERMAL)            += spear_thermal.o
> diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
> new file mode 100644
> index 0000000..c40d9a0
> --- /dev/null
> +++ b/drivers/thermal/cpu_cooling.c
> @@ -0,0 +1,483 @@
> +/*
> + *  linux/drivers/thermal/cpu_cooling.c
> + *
> + *  Copyright (C) 2012 Samsung Electronics Co., Ltd(
> http://www.samsung.com)
> + *  Copyright (C) 2012  Amit Daniel <amit.kachhap@linaro.org>
> + *
> + *
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> + *  This program is free software; you can redistribute it and/or modify
> + *  it under the terms of the GNU General Public License as published by
> + *  the Free Software Foundation; version 2 of the License.
> + *
> + *  This program is distributed in the hope that it will be useful, but
> + *  WITHOUT ANY WARRANTY; without even the implied warranty of
> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + *  General Public License for more details.
> + *
> + *  You should have received a copy of the GNU General Public License
> along
> + *  with this program; if not, write to the Free Software Foundation,
> Inc.,
> + *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
> + *
> + *
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> + */
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/thermal.h>
> +#include <linux/platform_device.h>
> +#include <linux/cpufreq.h>
> +#include <linux/err.h>
> +#include <linux/slab.h>
> +#include <linux/cpu.h>
> +#include <linux/cpu_cooling.h>
> +
> +/**
> + * struct cpufreq_cooling_device
> + * @id: unique integer value corresponding to each cpufreq_cooling_device
> + *     registered.
> + * @cool_dev: thermal_cooling_device pointer to keep track of the the
> + *     egistered cooling device.
> + * @tab_ptr: freq_clip_table table containing the maximum value of
> frequency to
> + *     be set for different cooling state.
> + * @tab_size: integer value representing a count of the above table.
> + * @cpufreq_state: integer value representing the current state of cpufreq
> + *     cooling devices.
> + * @allowed_cpus: all the cpus involved for this cpufreq_cooling_device.
> + * @node: list_head to link all cpufreq_cooling_device together.
> + *
> + * This structure is required for keeping information of each
> + * cpufreq_cooling_device registered as a list whose head is represented
> by
> + * cooling_cpufreq_list. In order to prevent corruption of this list a
> + * mutex lock cooling_cpufreq_lock is used.
> + */
> +struct cpufreq_cooling_device {
> +       int id;
> +       struct thermal_cooling_device *cool_dev;
> +       struct freq_clip_table *tab_ptr;
> +       unsigned int tab_size;
> +       unsigned int cpufreq_state;
> +       struct cpumask allowed_cpus;
> +       struct list_head node;
> +};
> +static LIST_HEAD(cooling_cpufreq_list);
> +static DEFINE_MUTEX(cooling_cpufreq_lock);
> +static DEFINE_IDR(cpufreq_idr);
> +
> +/*per cpu variable to store the previous max frequency allowed*/
> +static DEFINE_PER_CPU(unsigned int, max_policy_freq);
> +
> +/*notify_table passes value to the CPUFREQ_ADJUST callback function.*/
> +#define NOTIFY_INVALID NULL
> +static struct freq_clip_table *notify_table;
> +
> +/*Head of the blocking notifier chain to inform about frequency clamping*/
> +static BLOCKING_NOTIFIER_HEAD(cputherm_state_notifier_list);
> +
> +/**
> + * get_idr - function to get a unique id.
> + * @idr: struct idr * handle used to create a id.
> + * @id: int * value generated by this function.
> + */
> +static int get_idr(struct idr *idr, int *id)
> +{
> +       int err;
> +again:
> +       if (unlikely(idr_pre_get(idr, GFP_KERNEL) == 0))
> +               return -ENOMEM;
> +
> +       mutex_lock(&cooling_cpufreq_lock);
> +       err = idr_get_new(idr, NULL, id);
> +       mutex_unlock(&cooling_cpufreq_lock);
> +
> +       if (unlikely(err == -EAGAIN))
> +               goto again;
> +       else if (unlikely(err))
> +               return err;
> +
> +       *id = *id & MAX_ID_MASK;
> +       return 0;
> +}
> +
> +/**
> + * release_idr - function to free the unique id.
> + * @idr: struct idr * handle used for creating the id.
> + * @id: int value representing the unique id.
> + */
> +static void release_idr(struct idr *idr, int id)
> +{
> +       mutex_lock(&cooling_cpufreq_lock);
> +       idr_remove(idr, id);
> +       mutex_unlock(&cooling_cpufreq_lock);
> +}
> +
> +/**
> + * cputherm_register_notifier - Register a notifier with cpu cooling
> interface.
> + * @nb:        struct notifier_block * with callback info.
> + * @list: integer value for which notification is needed. possible values
> are
> + *     CPUFREQ_COOLING_START and CPUFREQ_COOLING_STOP.
> + *
> + * This exported function registers a driver with cpu cooling layer. The
> driver
> + * will be notified when any cpu cooling action is called.
> + */
> +int cputherm_register_notifier(struct notifier_block *nb, unsigned int
> list)
> +{
> +       int ret = 0;
> +
> +       switch (list) {
> +       case CPUFREQ_COOLING_START:
> +       case CPUFREQ_COOLING_STOP:
> +               ret = blocking_notifier_chain_register(
> +                               &cputherm_state_notifier_list, nb);
> +               break;
> +       default:
> +               ret = -EINVAL;
> +       }
> +       return ret;
> +}
> +EXPORT_SYMBOL(cputherm_register_notifier);
> +
> +/**
> + * cputherm_unregister_notifier - Un-register a notifier.
> + * @nb:        struct notifier_block * with callback info.
> + * @list: integer value for which notification is needed. values possible
> are
> + *     CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP.
> + *
> + * This exported function un-registers a driver with cpu cooling layer.
> + */
> +int cputherm_unregister_notifier(struct notifier_block *nb, unsigned int
> list)
> +{
> +       int ret = 0;
> +
> +       switch (list) {
> +       case CPUFREQ_COOLING_START:
> +       case CPUFREQ_COOLING_STOP:
> +               ret = blocking_notifier_chain_unregister(
> +                               &cputherm_state_notifier_list, nb);
> +               break;
> +       default:
> +               ret = -EINVAL;
> +       }
> +       return ret;
> +}
> +EXPORT_SYMBOL(cputherm_unregister_notifier);
> +
> +/*Below codes defines functions to be used for cpufreq as cooling device*/
> +
> +/**
> + * is_cpufreq_valid - function to check if a cpu has frequency transition
> policy.
> + * @cpu: cpu for which check is needed.
> + */
> +static int is_cpufreq_valid(int cpu)
> +{
> +       struct cpufreq_policy policy;
> +       return !cpufreq_get_policy(&policy, cpu);
> +}
> +
> +/**
> + * cpufreq_apply_cooling - function to apply frequency clipping.
> + * @cpufreq_device: cpufreq_cooling_device pointer containing frequency
> + *     clipping data.
> + * @cooling_state: value of the cooling state.
> + */
> +static int cpufreq_apply_cooling(struct cpufreq_cooling_device
> *cpufreq_device,
> +                               unsigned long cooling_state)
> +{
> +       unsigned int event, cpuid, state;
> +       struct freq_clip_table *th_table, *table_ptr;
> +       const struct cpumask *maskPtr = &cpufreq_device->allowed_cpus;
> +       struct cpufreq_cooling_device *cpufreq_ptr;
> +
> +       if (cooling_state > cpufreq_device->tab_size)
> +               return -EINVAL;
> +
> +       /*Check if the old cooling action is same as new cooling action*/
> +       if (cpufreq_device->cpufreq_state == cooling_state)
> +               return 0;
> +
> +       /*pass cooling table info to the cpufreq_thermal_notifier
> callback*/
> +       notify_table = NOTIFY_INVALID;
> +
> +       if (cooling_state > 0) {
> +               th_table = &(cpufreq_device->tab_ptr[cooling_state - 1]);
> +               notify_table = th_table;
> +       }
> +
> +       /*check if any lower clip frequency active in other
> cpufreq_device's*/
> +       list_for_each_entry(cpufreq_ptr, &cooling_cpufreq_list, node) {
> +
> +               state = cpufreq_ptr->cpufreq_state;
> +               if (state == 0 || cpufreq_ptr == cpufreq_device)
> +                       continue;
> +
> +               if (!cpumask_equal(&cpufreq_ptr->allowed_cpus,
> +                               &cpufreq_device->allowed_cpus))
> +                       continue;
> +
> +               table_ptr = &(cpufreq_ptr->tab_ptr[state - 1]);
> +               if (notify_table == NULL ||
> +                               (table_ptr->freq_clip_max <
> +                               notify_table->freq_clip_max))
> +                       notify_table =  table_ptr;
> +       }
> +
> +       cpufreq_device->cpufreq_state = cooling_state;
> +
> +       if (notify_table != NOTIFY_INVALID) {
> +               event = CPUFREQ_COOLING_START;
> +               maskPtr = notify_table->mask_val;
> +       } else {
> +               event = CPUFREQ_COOLING_STOP;
> +       }
> +
> +       blocking_notifier_call_chain(&cputherm_state_notifier_list,
> +                                               event, notify_table);
> +
> +       for_each_cpu(cpuid, maskPtr) {
> +               if (is_cpufreq_valid(cpuid))
> +                       cpufreq_update_policy(cpuid);
> +       }
> +
> +       notify_table = NOTIFY_INVALID;
> +
> +       return 0;
> +}
> +
> +/**
> + * cpufreq_thermal_notifier - notifier callback for cpufreq policy change.
> + * @nb:        struct notifier_block * with callback info.
> + * @event: value showing cpufreq event for which this function invoked.
> + * @data: callback-specific data
> + */
> +static int cpufreq_thermal_notifier(struct notifier_block *nb,
> +                                       unsigned long event, void *data)
> +{
> +       struct cpufreq_policy *policy = data;
> +       unsigned long max_freq = 0;
> +
> +       if (event != CPUFREQ_ADJUST)
> +               return 0;
> +
> +       if (notify_table != NOTIFY_INVALID) {
> +               max_freq = notify_table->freq_clip_max;
> +
> +               if (!per_cpu(max_policy_freq, policy->cpu))
> +                       per_cpu(max_policy_freq, policy->cpu) =
> policy->max;
> +       } else {
> +               if (per_cpu(max_policy_freq, policy->cpu)) {
> +                       max_freq = per_cpu(max_policy_freq, policy->cpu);
> +                       per_cpu(max_policy_freq, policy->cpu) = 0;
> +               } else {
> +                       max_freq = policy->max;
> +               }
> +       }
> +
> +       /* Never exceed user_policy.max*/
> +       if (max_freq > policy->user_policy.max)
> +               max_freq = policy->user_policy.max;
> +
> +       if (policy->max != max_freq)
> +               cpufreq_verify_within_limits(policy, 0, max_freq);
> +
> +       return 0;
> +}
> +
> +/*
> + * cpufreq cooling device callback functions are defined below
> + */
> +
> +/**
> + * cpufreq_get_max_state - callback function to get the max cooling state.
> + * @cdev: thermal cooling device pointer.
> + * @state: fill this variable with the max cooling state.
> + */
> +static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
> +                                unsigned long *state)
> +{
> +       int ret = -EINVAL;
> +       struct cpufreq_cooling_device *cpufreq_device;
> +
> +       mutex_lock(&cooling_cpufreq_lock);
> +       list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node) {
> +               if (cpufreq_device && cpufreq_device->cool_dev == cdev) {
> +                       *state = cpufreq_device->tab_size;
> +                       ret = 0;
> +                       break;
> +               }
> +       }
> +       mutex_unlock(&cooling_cpufreq_lock);
> +       return ret;
> +}
> +
> +/**
> + * cpufreq_get_cur_state - callback function to get the current cooling
> state.
> + * @cdev: thermal cooling device pointer.
> + * @state: fill this variable with the current cooling state.
> + */
> +static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
> +                                unsigned long *state)
> +{
> +       int ret = -EINVAL;
> +       struct cpufreq_cooling_device *cpufreq_device;
> +
> +       mutex_lock(&cooling_cpufreq_lock);
> +       list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node) {
> +               if (cpufreq_device && cpufreq_device->cool_dev == cdev) {
> +                       *state = cpufreq_device->cpufreq_state;
> +                       ret = 0;
> +                       break;
> +               }
> +       }
> +       mutex_unlock(&cooling_cpufreq_lock);
> +       return ret;
> +}
> +
> +/**
> + * cpufreq_set_cur_state - callback function to set the current cooling
> state.
> + * @cdev: thermal cooling device pointer.
> + * @state: set this variable to the current cooling state.
> + */
> +static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
> +                                unsigned long state)
> +{
> +       int ret = -EINVAL;
> +       struct cpufreq_cooling_device *cpufreq_device;
> +
> +       mutex_lock(&cooling_cpufreq_lock);
> +       list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node) {
> +               if (cpufreq_device && cpufreq_device->cool_dev == cdev) {
> +                       ret = 0;
> +                       break;
> +               }
> +       }
> +       if (!ret)
> +               ret = cpufreq_apply_cooling(cpufreq_device, state);
> +
> +       mutex_unlock(&cooling_cpufreq_lock);
> +
> +       return ret;
> +}
> +
> +/*Bind cpufreq callbacks to thermal cooling device ops*/
> +static struct thermal_cooling_device_ops const cpufreq_cooling_ops = {
> +       .get_max_state = cpufreq_get_max_state,
> +       .get_cur_state = cpufreq_get_cur_state,
> +       .set_cur_state = cpufreq_set_cur_state,
> +};
> +
> +/*Notifier for cpufreq policy change*/
> +static struct notifier_block thermal_cpufreq_notifier_block = {
> +       .notifier_call = cpufreq_thermal_notifier,
> +};
> +
> +/**
> + * cpufreq_cooling_register - function to create cpufreq cooling device.
> + * @tab_ptr: table ptr containing the maximum value of frequency to be
> clipped
> + *     for each cooling state.
> + * @tab_size: count of entries in the above table.
> + *     happen.
> + */
> +struct thermal_cooling_device *cpufreq_cooling_register(
> +       struct freq_clip_table *tab_ptr, unsigned int tab_size)
> +{
> +       struct thermal_cooling_device *cool_dev;
> +       struct cpufreq_cooling_device *cpufreq_dev = NULL;
> +       struct freq_clip_table *clip_tab;
> +       unsigned int cpufreq_dev_count = 0;
> +       char dev_name[THERMAL_NAME_LENGTH];
> +       int ret = 0, id = 0, i;
> +
> +       if (tab_ptr == NULL || tab_size == 0)
> +               return ERR_PTR(-EINVAL);
> +
> +       list_for_each_entry(cpufreq_dev, &cooling_cpufreq_list, node)
> +               cpufreq_dev_count++;
> +
> +       cpufreq_dev = kzalloc(sizeof(struct cpufreq_cooling_device),
> +                       GFP_KERNEL);
> +       if (!cpufreq_dev)
> +               return ERR_PTR(-ENOMEM);
> +
> +       /*Verify that all the entries of freq_clip_table are present*/
> +       for (i = 0; i < tab_size; i++) {
> +               clip_tab = ((struct freq_clip_table *)&tab_ptr[i]);
> +               if (!clip_tab->freq_clip_max || !clip_tab->mask_val
> +                                       || !clip_tab->temp_level) {
> +                       kfree(cpufreq_dev);
> +                       return ERR_PTR(-EINVAL);
> +               }
> +               /*
> +                *Consolidate all the cpumask for all the individual
> entries
> +                *of the trip table. This is useful in resetting all the
> +                *clipped frequencies to the normal level for each cpufreq
> +                *cooling device.
> +                */
> +               cpumask_or(&cpufreq_dev->allowed_cpus,
> +                       &cpufreq_dev->allowed_cpus, clip_tab->mask_val);
> +       }
> +
> +       cpufreq_dev->tab_ptr = tab_ptr;
> +       cpufreq_dev->tab_size = tab_size;
> +
> +       ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
> +       if (ret) {
> +               kfree(cpufreq_dev);
> +               return ERR_PTR(-EINVAL);
> +       }
> +
> +       sprintf(dev_name, "thermal-cpufreq-%d", cpufreq_dev->id);
> +
> +       cool_dev = thermal_cooling_device_register(dev_name, cpufreq_dev,
> +                                               &cpufreq_cooling_ops);
> +       if (!cool_dev) {
> +               release_idr(&cpufreq_idr, cpufreq_dev->id);
> +               kfree(cpufreq_dev);
> +               return ERR_PTR(-EINVAL);
> +       }
> +       cpufreq_dev->id = id;
> +       cpufreq_dev->cool_dev = cool_dev;
> +       mutex_lock(&cooling_cpufreq_lock);
> +       list_add_tail(&cpufreq_dev->node, &cooling_cpufreq_list);
> +
> +       /*Register the notifier for first cpufreq cooling device*/
> +       if (cpufreq_dev_count == 0)
> +               cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
> +                                               CPUFREQ_POLICY_NOTIFIER);
> +
> +       mutex_unlock(&cooling_cpufreq_lock);
> +       return cool_dev;
> +}
> +EXPORT_SYMBOL(cpufreq_cooling_register);
> +
> +/**
> + * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
> + * @cdev: thermal cooling device pointer.
> + */
> +void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
> +{
> +       struct cpufreq_cooling_device *cpufreq_dev = NULL;
> +       unsigned int cpufreq_dev_count = 0;
> +
> +       mutex_lock(&cooling_cpufreq_lock);
> +       list_for_each_entry(cpufreq_dev, &cooling_cpufreq_list, node) {
> +               if (cpufreq_dev && cpufreq_dev->cool_dev == cdev)
> +                       break;
> +               cpufreq_dev_count++;
> +       }
> +
> +       if (!cpufreq_dev || cpufreq_dev->cool_dev != cdev) {
> +               mutex_unlock(&cooling_cpufreq_lock);
> +               return;
> +       }
> +
> +       list_del(&cpufreq_dev->node);
> +
> +       /*Unregister the notifier for the last cpufreq cooling device*/
> +       if (cpufreq_dev_count == 1) {
> +
> cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
> +                                       CPUFREQ_POLICY_NOTIFIER);
> +       }
> +       mutex_unlock(&cooling_cpufreq_lock);
> +       thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
> +       release_idr(&cpufreq_idr, cpufreq_dev->id);
> +       kfree(cpufreq_dev);
> +}
> +EXPORT_SYMBOL(cpufreq_cooling_unregister);
> diff --git a/include/linux/cpu_cooling.h b/include/linux/cpu_cooling.h
> new file mode 100644
> index 0000000..ed6c096
> --- /dev/null
> +++ b/include/linux/cpu_cooling.h
> @@ -0,0 +1,99 @@
> +/*
> + *  linux/include/linux/cpu_cooling.h
> + *
> + *  Copyright (C) 2012 Samsung Electronics Co., Ltd(
> http://www.samsung.com)
> + *  Copyright (C) 2012  Amit Daniel <amit.kachhap@linaro.org>
> + *
> + *
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> + *  This program is free software; you can redistribute it and/or modify
> + *  it under the terms of the GNU General Public License as published by
> + *  the Free Software Foundation; version 2 of the License.
> + *
> + *  This program is distributed in the hope that it will be useful, but
> + *  WITHOUT ANY WARRANTY; without even the implied warranty of
> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + *  General Public License for more details.
> + *
> + *  You should have received a copy of the GNU General Public License
> along
> + *  with this program; if not, write to the Free Software Foundation,
> Inc.,
> + *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
> + *
> + *
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> + */
> +
> +#ifndef __CPU_COOLING_H__
> +#define __CPU_COOLING_H__
> +
> +#include <linux/thermal.h>
> +
> +#define CPUFREQ_COOLING_START          0
> +#define CPUFREQ_COOLING_STOP           1
> +
> +/**
> + * struct freq_clip_table
> + * @freq_clip_max: maximum frequency allowed for this cooling state.
> + * @temp_level: Temperature level at which the temperature clipping will
> + *     happen.
> + * @mask_val: cpumask of the allowed cpu's where the clipping will take
> place.
> + *
> + * This structure is required to be filled and passed to the
> + * cpufreq_cooling_unregister function.
> + */
> +struct freq_clip_table {
> +       unsigned int freq_clip_max;
> +       unsigned int temp_level;
> +       const struct cpumask *mask_val;
> +};
> +
> +/**
> + * cputherm_register_notifier - Register a notifier with cpu cooling
> interface.
> + * @nb:        struct notifier_block * with callback info.
> + * @list: integer value for which notification is needed. possible values
> are
> + *     CPUFREQ_COOLING_TYPE and CPUHOTPLUG_COOLING_TYPE.
> + *
> + * This exported function registers a driver with cpu cooling layer. The
> driver
> + * will be notified when any cpu cooling action is called.
> + */
> +int cputherm_register_notifier(struct notifier_block *nb, unsigned int
> list);
> +
> +/**
> + * cputherm_unregister_notifier - Un-register a notifier.
> + * @nb:        struct notifier_block * with callback info.
> + * @list: integer value for which notification is needed. values possible
> are
> + *     CPUFREQ_COOLING_TYPE.
> + *
> + * This exported function un-registers a driver with cpu cooling layer.
> + */
> +int cputherm_unregister_notifier(struct notifier_block *nb, unsigned int
> list);
> +
> +#ifdef CONFIG_CPU_FREQ
> +/**
> + * cpufreq_cooling_register - function to create cpufreq cooling device.
> + * @tab_ptr: table ptr containing the maximum value of frequency to be
> clipped
> + *     for each cooling state.
> + * @tab_size: count of entries in the above table.
> + * @mask_val: cpumask containing the allowed cpu's where frequency
> clipping can
> + *     happen.
> + */
> +struct thermal_cooling_device *cpufreq_cooling_register(
> +       struct freq_clip_table *tab_ptr, unsigned int tab_size);
> +
> +/**
> + * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
> + * @cdev: thermal cooling device pointer.
> + */
> +void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev);
> +#else /*!CONFIG_CPU_FREQ*/
> +static inline struct thermal_cooling_device *cpufreq_cooling_register(
> +       struct freq_clip_table *tab_ptr, unsigned int tab_size);
> +{
> +       return NULL;
> +}
> +static inline void cpufreq_cooling_unregister(
> +               struct thermal_cooling_device *cdev)
> +{
> +       return;
> +}
> +#endif /*CONFIG_CPU_FREQ*/
> +
> +#endif /* __CPU_COOLING_H__ */
> --
> 1.7.1
>
>
> _______________________________________________
> linaro-dev mailing list
> linaro-dev@lists.linaro.org
> http://lists.linaro.org/mailman/listinfo/linaro-dev
>

On Fri, Jul 13, 2012 at 3:39 PM, Hongbo Zhang <hongbo.zhang@linaro.org> wrote:
>
>
> On 12 May 2012 17:40, Amit Daniel Kachhap <amit.kachhap@linaro.org> wrote:
>>
>> This patch adds support for generic cpu thermal cooling low level
>> implementations using frequency scaling up/down based on the registration
>> parameters. Different cpu related cooling devices can be registered by the
>> user and the binding of these cooling devices to the corresponding
>> trip points can be easily done as the registration APIs return the
>> cooling device pointer. The user of these APIs are responsible for
>> passing clipping frequency . The drivers can also register to recieve
>> notification about any cooling action called.
>>
>> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@linaro.org>
>> ---
>>  Documentation/thermal/cpu-cooling-api.txt |   60 ++++
>>  drivers/thermal/Kconfig                   |   11 +
>>  drivers/thermal/Makefile                  |    3 +-
>>  drivers/thermal/cpu_cooling.c             |  483
>> +++++++++++++++++++++++++++++
>>  include/linux/cpu_cooling.h               |   99 ++++++
>>  5 files changed, 655 insertions(+), 1 deletions(-)
>>  create mode 100644 Documentation/thermal/cpu-cooling-api.txt
>>  create mode 100644 drivers/thermal/cpu_cooling.c
>>  create mode 100644 include/linux/cpu_cooling.h
>>
>> diff --git a/Documentation/thermal/cpu-cooling-api.txt
>> b/Documentation/thermal/cpu-cooling-api.txt
>> new file mode 100644
>> index 0000000..557adb8
>> --- /dev/null
>> +++ b/Documentation/thermal/cpu-cooling-api.txt
>> @@ -0,0 +1,60 @@
>> +CPU cooling APIs How To
>> +===================================
>> +
>> +Written by Amit Daniel Kachhap <amit.kachhap@linaro.org>
>> +
>> +Updated: 12 May 2012
>> +
>> +Copyright (c)  2012 Samsung Electronics Co., Ltd(http://www.samsung.com)
>> +
>> +0. Introduction
>> +
>> +The generic cpu cooling(freq clipping, cpuhotplug etc) provides
>> +registration/unregistration APIs to the caller. The binding of the
>> cooling
>> +devices to the trip point is left for the user. The registration APIs
>> returns
>> +the cooling device pointer.
>> +
>> +1. cpu cooling APIs
>> +
>> +1.1 cpufreq registration/unregistration APIs
>> +1.1.1 struct thermal_cooling_device *cpufreq_cooling_register(
>> +       struct freq_clip_table *tab_ptr, unsigned int tab_size)
>> +
>> +    This interface function registers the cpufreq cooling device with the
>> name
>> +    "thermal-cpufreq-%x". This api can support multiple instances of
>> cpufreq
>> +    cooling devices.
>> +
>> +    tab_ptr: The table containing the maximum value of frequency to be
>> clipped
>> +    for each cooling state.
>> +       .freq_clip_max: Value of frequency to be clipped for each allowed
>> +        cpus.
>> +       .temp_level: Temperature level at which the frequency clamping
>> will
>> +       happen.
>> +       .mask_val: cpumask of the allowed cpu's
>> +    tab_size: the total number of cpufreq cooling states.
>> +
>> +1.1.2 void cpufreq_cooling_unregister(struct thermal_cooling_device
>> *cdev)
>> +
>> +    This interface function unregisters the "thermal-cpufreq-%x" cooling
>> device.
>> +
>> +    cdev: Cooling device pointer which has to be unregistered.
>> +
>> +
>> +1.2 CPU cooling action notifier register/unregister interface
>> +1.2.1 int cputherm_register_notifier(struct notifier_block *nb,
>> +       unsigned int list)
>> +
>> +    This interface registers a driver with cpu cooling layer. The driver
>> will
>> +    be notified when any cpu cooling action is called.
>> +
>> +    nb: notifier function to register
>> +    list: CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP
>> +
>> +1.2.2 int cputherm_unregister_notifier(struct notifier_block *nb,
>> +       unsigned int list)
>> +
>> +    This interface registers a driver with cpu cooling layer. The driver
>> will
>> +    be notified when any cpu cooling action is called.
>> +
>> +    nb: notifier function to register
>> +    list: CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP
>> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
>> index 514a691..d9c529f 100644
>> --- a/drivers/thermal/Kconfig
>> +++ b/drivers/thermal/Kconfig
>> @@ -19,6 +19,17 @@ config THERMAL_HWMON
>>         depends on HWMON=y || HWMON=THERMAL
>>         default y
>>
>> +config CPU_THERMAL
>> +       bool "generic cpu cooling support"
>> +       depends on THERMAL && CPU_FREQ
>> +       help
>> +         This implements the generic cpu cooling mechanism through
>> frequency
>> +         reduction, cpu hotplug and any other ways of reducing
>> temperature. An
>> +         ACPI version of this already
>> exists(drivers/acpi/processor_thermal.c).
>> +         This will be useful for platforms using the generic thermal
>> interface
>> +         and not the ACPI interface.
>> +         If you want this support, you should say Y or M here.
>
> No M value for bool item, should be N ?
Yes I will include this change.
>>
>> +
>>  config SPEAR_THERMAL
>>         bool "SPEAr thermal sensor driver"
>>         depends on THERMAL
>> diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
>> index a9fff0b..30c456c 100644
>> --- a/drivers/thermal/Makefile
>> +++ b/drivers/thermal/Makefile
>> @@ -3,4 +3,5 @@
>>  #
>>
>>  obj-$(CONFIG_THERMAL)          += thermal_sys.o
>> -obj-$(CONFIG_SPEAR_THERMAL)            += spear_thermal.o
>> \ No newline at end of file
>> +obj-$(CONFIG_CPU_THERMAL)       += cpu_cooling.o
>> +obj-$(CONFIG_SPEAR_THERMAL)            += spear_thermal.o
>> diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
>> new file mode 100644
>> index 0000000..c40d9a0
>> --- /dev/null
>> +++ b/drivers/thermal/cpu_cooling.c
>> @@ -0,0 +1,483 @@
>> +/*
>> + *  linux/drivers/thermal/cpu_cooling.c
>> + *
>> + *  Copyright (C) 2012 Samsung Electronics Co.,
>> Ltd(http://www.samsung.com)
>> + *  Copyright (C) 2012  Amit Daniel <amit.kachhap@linaro.org>
>> + *
>> + *
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> + *  This program is free software; you can redistribute it and/or modify
>> + *  it under the terms of the GNU General Public License as published by
>> + *  the Free Software Foundation; version 2 of the License.
>> + *
>> + *  This program is distributed in the hope that it will be useful, but
>> + *  WITHOUT ANY WARRANTY; without even the implied warranty of
>> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>> + *  General Public License for more details.
>> + *
>> + *  You should have received a copy of the GNU General Public License
>> along
>> + *  with this program; if not, write to the Free Software Foundation,
>> Inc.,
>> + *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
>> + *
>> + *
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> + */
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/thermal.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/cpufreq.h>
>> +#include <linux/err.h>
>> +#include <linux/slab.h>
>> +#include <linux/cpu.h>
>> +#include <linux/cpu_cooling.h>
>> +
>> +/**
>> + * struct cpufreq_cooling_device
>> + * @id: unique integer value corresponding to each cpufreq_cooling_device
>> + *     registered.
>> + * @cool_dev: thermal_cooling_device pointer to keep track of the the
>> + *     egistered cooling device.
>> + * @tab_ptr: freq_clip_table table containing the maximum value of
>> frequency to
>> + *     be set for different cooling state.
>> + * @tab_size: integer value representing a count of the above table.
>> + * @cpufreq_state: integer value representing the current state of
>> cpufreq
>> + *     cooling devices.
>> + * @allowed_cpus: all the cpus involved for this cpufreq_cooling_device.
>> + * @node: list_head to link all cpufreq_cooling_device together.
>> + *
>> + * This structure is required for keeping information of each
>> + * cpufreq_cooling_device registered as a list whose head is represented
>> by
>> + * cooling_cpufreq_list. In order to prevent corruption of this list a
>> + * mutex lock cooling_cpufreq_lock is used.
>> + */
>> +struct cpufreq_cooling_device {
>> +       int id;
>> +       struct thermal_cooling_device *cool_dev;
>> +       struct freq_clip_table *tab_ptr;
>> +       unsigned int tab_size;
>> +       unsigned int cpufreq_state;
>> +       struct cpumask allowed_cpus;
>> +       struct list_head node;
>> +};
>> +static LIST_HEAD(cooling_cpufreq_list);
>> +static DEFINE_MUTEX(cooling_cpufreq_lock);
>> +static DEFINE_IDR(cpufreq_idr);
>> +
>> +/*per cpu variable to store the previous max frequency allowed*/
>> +static DEFINE_PER_CPU(unsigned int, max_policy_freq);
>> +
>> +/*notify_table passes value to the CPUFREQ_ADJUST callback function.*/
>> +#define NOTIFY_INVALID NULL
>> +static struct freq_clip_table *notify_table;
>> +
>> +/*Head of the blocking notifier chain to inform about frequency
>> clamping*/
>> +static BLOCKING_NOTIFIER_HEAD(cputherm_state_notifier_list);
>> +
>> +/**
>> + * get_idr - function to get a unique id.
>> + * @idr: struct idr * handle used to create a id.
>> + * @id: int * value generated by this function.
>> + */
>> +static int get_idr(struct idr *idr, int *id)
>> +{
>> +       int err;
>> +again:
>> +       if (unlikely(idr_pre_get(idr, GFP_KERNEL) == 0))
>> +               return -ENOMEM;
>> +
>> +       mutex_lock(&cooling_cpufreq_lock);
>> +       err = idr_get_new(idr, NULL, id);
>> +       mutex_unlock(&cooling_cpufreq_lock);
>> +
>> +       if (unlikely(err == -EAGAIN))
>> +               goto again;
>> +       else if (unlikely(err))
>> +               return err;
>> +
>> +       *id = *id & MAX_ID_MASK;
>> +       return 0;
>> +}
>> +
>> +/**
>> + * release_idr - function to free the unique id.
>> + * @idr: struct idr * handle used for creating the id.
>> + * @id: int value representing the unique id.
>> + */
>> +static void release_idr(struct idr *idr, int id)
>> +{
>> +       mutex_lock(&cooling_cpufreq_lock);
>> +       idr_remove(idr, id);
>> +       mutex_unlock(&cooling_cpufreq_lock);
>> +}
>> +
>> +/**
>> + * cputherm_register_notifier - Register a notifier with cpu cooling
>> interface.
>> + * @nb:        struct notifier_block * with callback info.
>> + * @list: integer value for which notification is needed. possible values
>> are
>> + *     CPUFREQ_COOLING_START and CPUFREQ_COOLING_STOP.
>> + *
>> + * This exported function registers a driver with cpu cooling layer. The
>> driver
>> + * will be notified when any cpu cooling action is called.
>> + */
>> +int cputherm_register_notifier(struct notifier_block *nb, unsigned int
>> list)
>> +{
>> +       int ret = 0;
>> +
>> +       switch (list) {
>> +       case CPUFREQ_COOLING_START:
>> +       case CPUFREQ_COOLING_STOP:
>> +               ret = blocking_notifier_chain_register(
>> +                               &cputherm_state_notifier_list, nb);
>> +               break;
>> +       default:
>> +               ret = -EINVAL;
>> +       }
>> +       return ret;
>> +}
>> +EXPORT_SYMBOL(cputherm_register_notifier);
>> +
>> +/**
>> + * cputherm_unregister_notifier - Un-register a notifier.
>> + * @nb:        struct notifier_block * with callback info.
>> + * @list: integer value for which notification is needed. values possible
>> are
>> + *     CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP.
>> + *
>> + * This exported function un-registers a driver with cpu cooling layer.
>> + */
>> +int cputherm_unregister_notifier(struct notifier_block *nb, unsigned int
>> list)
>> +{
>> +       int ret = 0;
>> +
>> +       switch (list) {
>> +       case CPUFREQ_COOLING_START:
>> +       case CPUFREQ_COOLING_STOP:
>> +               ret = blocking_notifier_chain_unregister(
>> +                               &cputherm_state_notifier_list, nb);
>> +               break;
>> +       default:
>> +               ret = -EINVAL;
>> +       }
>> +       return ret;
>> +}
>> +EXPORT_SYMBOL(cputherm_unregister_notifier);
>> +
>> +/*Below codes defines functions to be used for cpufreq as cooling
>> device*/
>> +
>> +/**
>> + * is_cpufreq_valid - function to check if a cpu has frequency transition
>> policy.
>> + * @cpu: cpu for which check is needed.
>> + */
>> +static int is_cpufreq_valid(int cpu)
>> +{
>> +       struct cpufreq_policy policy;
>> +       return !cpufreq_get_policy(&policy, cpu);
>> +}
>> +
>> +/**
>> + * cpufreq_apply_cooling - function to apply frequency clipping.
>> + * @cpufreq_device: cpufreq_cooling_device pointer containing frequency
>> + *     clipping data.
>> + * @cooling_state: value of the cooling state.
>> + */
>> +static int cpufreq_apply_cooling(struct cpufreq_cooling_device
>> *cpufreq_device,
>> +                               unsigned long cooling_state)
>> +{
>> +       unsigned int event, cpuid, state;
>> +       struct freq_clip_table *th_table, *table_ptr;
>> +       const struct cpumask *maskPtr = &cpufreq_device->allowed_cpus;
>> +       struct cpufreq_cooling_device *cpufreq_ptr;
>> +
>> +       if (cooling_state > cpufreq_device->tab_size)
>> +               return -EINVAL;
>> +
>> +       /*Check if the old cooling action is same as new cooling action*/
>> +       if (cpufreq_device->cpufreq_state == cooling_state)
>> +               return 0;
>> +
>> +       /*pass cooling table info to the cpufreq_thermal_notifier
>> callback*/
>> +       notify_table = NOTIFY_INVALID;
>> +
>> +       if (cooling_state > 0) {
>> +               th_table = &(cpufreq_device->tab_ptr[cooling_state - 1]);
>> +               notify_table = th_table;
>> +       }
>> +
>> +       /*check if any lower clip frequency active in other
>> cpufreq_device's*/
>> +       list_for_each_entry(cpufreq_ptr, &cooling_cpufreq_list, node) {
>> +
>> +               state = cpufreq_ptr->cpufreq_state;
>> +               if (state == 0 || cpufreq_ptr == cpufreq_device)
>> +                       continue;
>> +
>> +               if (!cpumask_equal(&cpufreq_ptr->allowed_cpus,
>> +                               &cpufreq_device->allowed_cpus))
>> +                       continue;
>> +
>> +               table_ptr = &(cpufreq_ptr->tab_ptr[state - 1]);
>> +               if (notify_table == NULL ||
>> +                               (table_ptr->freq_clip_max <
>> +                               notify_table->freq_clip_max))
>> +                       notify_table =  table_ptr;
>> +       }
>> +
>> +       cpufreq_device->cpufreq_state = cooling_state;
>> +
>> +       if (notify_table != NOTIFY_INVALID) {
>> +               event = CPUFREQ_COOLING_START;
>> +               maskPtr = notify_table->mask_val;
>> +       } else {
>> +               event = CPUFREQ_COOLING_STOP;
>> +       }
>> +
>> +       blocking_notifier_call_chain(&cputherm_state_notifier_list,
>> +                                               event, notify_table);
>> +
>> +       for_each_cpu(cpuid, maskPtr) {
>> +               if (is_cpufreq_valid(cpuid))
>> +                       cpufreq_update_policy(cpuid);
>> +       }
>> +
>> +       notify_table = NOTIFY_INVALID;
>> +
>> +       return 0;
>> +}
>> +
>> +/**
>> + * cpufreq_thermal_notifier - notifier callback for cpufreq policy
>> change.
>> + * @nb:        struct notifier_block * with callback info.
>> + * @event: value showing cpufreq event for which this function invoked.
>> + * @data: callback-specific data
>> + */
>> +static int cpufreq_thermal_notifier(struct notifier_block *nb,
>> +                                       unsigned long event, void *data)
>> +{
>> +       struct cpufreq_policy *policy = data;
>> +       unsigned long max_freq = 0;
>> +
>> +       if (event != CPUFREQ_ADJUST)
>> +               return 0;
>> +
>> +       if (notify_table != NOTIFY_INVALID) {
>> +               max_freq = notify_table->freq_clip_max;
>> +
>> +               if (!per_cpu(max_policy_freq, policy->cpu))
>> +                       per_cpu(max_policy_freq, policy->cpu) =
>> policy->max;
>> +       } else {
>> +               if (per_cpu(max_policy_freq, policy->cpu)) {
>> +                       max_freq = per_cpu(max_policy_freq, policy->cpu);
>> +                       per_cpu(max_policy_freq, policy->cpu) = 0;
>> +               } else {
>> +                       max_freq = policy->max;
>> +               }
>> +       }
>> +
>> +       /* Never exceed user_policy.max*/
>> +       if (max_freq > policy->user_policy.max)
>> +               max_freq = policy->user_policy.max;
>> +
>> +       if (policy->max != max_freq)
>> +               cpufreq_verify_within_limits(policy, 0, max_freq);
>> +
>> +       return 0;
>> +}
>> +
>> +/*
>> + * cpufreq cooling device callback functions are defined below
>> + */
>> +
>> +/**
>> + * cpufreq_get_max_state - callback function to get the max cooling
>> state.
>> + * @cdev: thermal cooling device pointer.
>> + * @state: fill this variable with the max cooling state.
>> + */
>> +static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
>> +                                unsigned long *state)
>> +{
>> +       int ret = -EINVAL;
>> +       struct cpufreq_cooling_device *cpufreq_device;
>> +
>> +       mutex_lock(&cooling_cpufreq_lock);
>> +       list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node) {
>> +               if (cpufreq_device && cpufreq_device->cool_dev == cdev) {
>> +                       *state = cpufreq_device->tab_size;
>> +                       ret = 0;
>> +                       break;
>> +               }
>> +       }
>> +       mutex_unlock(&cooling_cpufreq_lock);
>> +       return ret;
>> +}
>> +
>> +/**
>> + * cpufreq_get_cur_state - callback function to get the current cooling
>> state.
>> + * @cdev: thermal cooling device pointer.
>> + * @state: fill this variable with the current cooling state.
>> + */
>> +static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
>> +                                unsigned long *state)
>> +{
>> +       int ret = -EINVAL;
>> +       struct cpufreq_cooling_device *cpufreq_device;
>> +
>> +       mutex_lock(&cooling_cpufreq_lock);
>> +       list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node) {
>> +               if (cpufreq_device && cpufreq_device->cool_dev == cdev) {
>> +                       *state = cpufreq_device->cpufreq_state;
>> +                       ret = 0;
>> +                       break;
>> +               }
>> +       }
>> +       mutex_unlock(&cooling_cpufreq_lock);
>> +       return ret;
>> +}
>> +
>> +/**
>> + * cpufreq_set_cur_state - callback function to set the current cooling
>> state.
>> + * @cdev: thermal cooling device pointer.
>> + * @state: set this variable to the current cooling state.
>> + */
>> +static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
>> +                                unsigned long state)
>> +{
>> +       int ret = -EINVAL;
>> +       struct cpufreq_cooling_device *cpufreq_device;
>> +
>> +       mutex_lock(&cooling_cpufreq_lock);
>> +       list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node) {
>> +               if (cpufreq_device && cpufreq_device->cool_dev == cdev) {
>> +                       ret = 0;
>> +                       break;
>> +               }
>> +       }
>> +       if (!ret)
>> +               ret = cpufreq_apply_cooling(cpufreq_device, state);
>> +
>> +       mutex_unlock(&cooling_cpufreq_lock);
>> +
>> +       return ret;
>> +}
>> +
>> +/*Bind cpufreq callbacks to thermal cooling device ops*/
>> +static struct thermal_cooling_device_ops const cpufreq_cooling_ops = {
>> +       .get_max_state = cpufreq_get_max_state,
>> +       .get_cur_state = cpufreq_get_cur_state,
>> +       .set_cur_state = cpufreq_set_cur_state,
>> +};
>> +
>> +/*Notifier for cpufreq policy change*/
>> +static struct notifier_block thermal_cpufreq_notifier_block = {
>> +       .notifier_call = cpufreq_thermal_notifier,
>> +};
>> +
>> +/**
>> + * cpufreq_cooling_register - function to create cpufreq cooling device.
>> + * @tab_ptr: table ptr containing the maximum value of frequency to be
>> clipped
>> + *     for each cooling state.
>> + * @tab_size: count of entries in the above table.
>> + *     happen.
>> + */
>> +struct thermal_cooling_device *cpufreq_cooling_register(
>> +       struct freq_clip_table *tab_ptr, unsigned int tab_size)
>> +{
>> +       struct thermal_cooling_device *cool_dev;
>> +       struct cpufreq_cooling_device *cpufreq_dev = NULL;
>> +       struct freq_clip_table *clip_tab;
>> +       unsigned int cpufreq_dev_count = 0;
>> +       char dev_name[THERMAL_NAME_LENGTH];
>> +       int ret = 0, id = 0, i;
>> +
>> +       if (tab_ptr == NULL || tab_size == 0)
>> +               return ERR_PTR(-EINVAL);
>> +
>> +       list_for_each_entry(cpufreq_dev, &cooling_cpufreq_list, node)
>> +               cpufreq_dev_count++;
>> +
>> +       cpufreq_dev = kzalloc(sizeof(struct cpufreq_cooling_device),
>> +                       GFP_KERNEL);
>> +       if (!cpufreq_dev)
>> +               return ERR_PTR(-ENOMEM);
>> +
>> +       /*Verify that all the entries of freq_clip_table are present*/
>> +       for (i = 0; i < tab_size; i++) {
>> +               clip_tab = ((struct freq_clip_table *)&tab_ptr[i]);
>> +               if (!clip_tab->freq_clip_max || !clip_tab->mask_val
>> +                                       || !clip_tab->temp_level) {
>> +                       kfree(cpufreq_dev);
>> +                       return ERR_PTR(-EINVAL);
>> +               }
>> +               /*
>> +                *Consolidate all the cpumask for all the individual
>> entries
>> +                *of the trip table. This is useful in resetting all the
>> +                *clipped frequencies to the normal level for each cpufreq
>> +                *cooling device.
>> +                */
>> +               cpumask_or(&cpufreq_dev->allowed_cpus,
>> +                       &cpufreq_dev->allowed_cpus, clip_tab->mask_val);
>> +       }
>> +
>> +       cpufreq_dev->tab_ptr = tab_ptr;
>> +       cpufreq_dev->tab_size = tab_size;
>> +
>> +       ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
>> +       if (ret) {
>> +               kfree(cpufreq_dev);
>> +               return ERR_PTR(-EINVAL);
>> +       }
>> +
>> +       sprintf(dev_name, "thermal-cpufreq-%d", cpufreq_dev->id);
>> +
>> +       cool_dev = thermal_cooling_device_register(dev_name, cpufreq_dev,
>> +                                               &cpufreq_cooling_ops);
>> +       if (!cool_dev) {
>> +               release_idr(&cpufreq_idr, cpufreq_dev->id);
>> +               kfree(cpufreq_dev);
>> +               return ERR_PTR(-EINVAL);
>> +       }
>> +       cpufreq_dev->id = id;
>> +       cpufreq_dev->cool_dev = cool_dev;
>> +       mutex_lock(&cooling_cpufreq_lock);
>> +       list_add_tail(&cpufreq_dev->node, &cooling_cpufreq_list);
>> +
>> +       /*Register the notifier for first cpufreq cooling device*/
>> +       if (cpufreq_dev_count == 0)
>> +               cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
>> +                                               CPUFREQ_POLICY_NOTIFIER);
>> +
>> +       mutex_unlock(&cooling_cpufreq_lock);
>> +       return cool_dev;
>> +}
>> +EXPORT_SYMBOL(cpufreq_cooling_register);
>> +
>> +/**
>> + * cpufreq_cooling_unregister - function to remove cpufreq cooling
>> device.
>> + * @cdev: thermal cooling device pointer.
>> + */
>> +void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
>> +{
>> +       struct cpufreq_cooling_device *cpufreq_dev = NULL;
>> +       unsigned int cpufreq_dev_count = 0;
>> +
>> +       mutex_lock(&cooling_cpufreq_lock);
>> +       list_for_each_entry(cpufreq_dev, &cooling_cpufreq_list, node) {
>> +               if (cpufreq_dev && cpufreq_dev->cool_dev == cdev)
>> +                       break;
>> +               cpufreq_dev_count++;
>> +       }
>> +
>> +       if (!cpufreq_dev || cpufreq_dev->cool_dev != cdev) {
>> +               mutex_unlock(&cooling_cpufreq_lock);
>> +               return;
>> +       }
>> +
>> +       list_del(&cpufreq_dev->node);
>> +
>> +       /*Unregister the notifier for the last cpufreq cooling device*/
>> +       if (cpufreq_dev_count == 1) {
>> +
>> cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
>> +                                       CPUFREQ_POLICY_NOTIFIER);
>> +       }
>> +       mutex_unlock(&cooling_cpufreq_lock);
>> +       thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
>> +       release_idr(&cpufreq_idr, cpufreq_dev->id);
>> +       kfree(cpufreq_dev);
>> +}
>> +EXPORT_SYMBOL(cpufreq_cooling_unregister);
>> diff --git a/include/linux/cpu_cooling.h b/include/linux/cpu_cooling.h
>> new file mode 100644
>> index 0000000..ed6c096
>> --- /dev/null
>> +++ b/include/linux/cpu_cooling.h
>> @@ -0,0 +1,99 @@
>> +/*
>> + *  linux/include/linux/cpu_cooling.h
>> + *
>> + *  Copyright (C) 2012 Samsung Electronics Co.,
>> Ltd(http://www.samsung.com)
>> + *  Copyright (C) 2012  Amit Daniel <amit.kachhap@linaro.org>
>> + *
>> + *
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> + *  This program is free software; you can redistribute it and/or modify
>> + *  it under the terms of the GNU General Public License as published by
>> + *  the Free Software Foundation; version 2 of the License.
>> + *
>> + *  This program is distributed in the hope that it will be useful, but
>> + *  WITHOUT ANY WARRANTY; without even the implied warranty of
>> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>> + *  General Public License for more details.
>> + *
>> + *  You should have received a copy of the GNU General Public License
>> along
>> + *  with this program; if not, write to the Free Software Foundation,
>> Inc.,
>> + *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
>> + *
>> + *
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> + */
>> +
>> +#ifndef __CPU_COOLING_H__
>> +#define __CPU_COOLING_H__
>> +
>> +#include <linux/thermal.h>
>> +
>> +#define CPUFREQ_COOLING_START          0
>> +#define CPUFREQ_COOLING_STOP           1
>> +
>> +/**
>> + * struct freq_clip_table
>> + * @freq_clip_max: maximum frequency allowed for this cooling state.
>> + * @temp_level: Temperature level at which the temperature clipping will
>> + *     happen.
>> + * @mask_val: cpumask of the allowed cpu's where the clipping will take
>> place.
>> + *
>> + * This structure is required to be filled and passed to the
>> + * cpufreq_cooling_unregister function.
>> + */
>> +struct freq_clip_table {
>> +       unsigned int freq_clip_max;
>> +       unsigned int temp_level;
>> +       const struct cpumask *mask_val;
>> +};
>> +
>> +/**
>> + * cputherm_register_notifier - Register a notifier with cpu cooling
>> interface.
>> + * @nb:        struct notifier_block * with callback info.
>> + * @list: integer value for which notification is needed. possible values
>> are
>> + *     CPUFREQ_COOLING_TYPE and CPUHOTPLUG_COOLING_TYPE.
>> + *
>> + * This exported function registers a driver with cpu cooling layer. The
>> driver
>> + * will be notified when any cpu cooling action is called.
>> + */
>> +int cputherm_register_notifier(struct notifier_block *nb, unsigned int
>> list);
>> +
>> +/**
>> + * cputherm_unregister_notifier - Un-register a notifier.
>> + * @nb:        struct notifier_block * with callback info.
>> + * @list: integer value for which notification is needed. values possible
>> are
>> + *     CPUFREQ_COOLING_TYPE.
>> + *
>> + * This exported function un-registers a driver with cpu cooling layer.
>> + */
>> +int cputherm_unregister_notifier(struct notifier_block *nb, unsigned int
>> list);
>> +
>> +#ifdef CONFIG_CPU_FREQ
>> +/**
>> + * cpufreq_cooling_register - function to create cpufreq cooling device.
>> + * @tab_ptr: table ptr containing the maximum value of frequency to be
>> clipped
>> + *     for each cooling state.
>> + * @tab_size: count of entries in the above table.
>> + * @mask_val: cpumask containing the allowed cpu's where frequency
>> clipping can
>> + *     happen.
>> + */
>> +struct thermal_cooling_device *cpufreq_cooling_register(
>> +       struct freq_clip_table *tab_ptr, unsigned int tab_size);
>> +
>> +/**
>> + * cpufreq_cooling_unregister - function to remove cpufreq cooling
>> device.
>> + * @cdev: thermal cooling device pointer.
>> + */
>> +void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev);
>> +#else /*!CONFIG_CPU_FREQ*/
>> +static inline struct thermal_cooling_device *cpufreq_cooling_register(
>> +       struct freq_clip_table *tab_ptr, unsigned int tab_size);
>> +{
>> +       return NULL;
>> +}
>> +static inline void cpufreq_cooling_unregister(
>> +               struct thermal_cooling_device *cdev)
>> +{
>> +       return;
>> +}
>> +#endif /*CONFIG_CPU_FREQ*/
>> +
>> +#endif /* __CPU_COOLING_H__ */
>> --
>> 1.7.1
>>
>>
>> _______________________________________________
>>
>> linaro-dev mailing list
>> linaro-dev@lists.linaro.org
>> http://lists.linaro.org/mailman/listinfo/linaro-dev
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