[v1,0/3] Add support for EMC2305 Fan Speed Controller.

From: Michael Shych <michaelsh@nvidia.com>

Introduce EMC2305 RPM-based PWM Fan Speed Controller
The EMC2305 is an SMBus compliant fan controller with up to five
controlled PWM fan drivers. All fan drivers are
controlled by a programmable frequency PWM driver and Fan Speed
Control algorithm that operates as a directly PWM-controlled device.

The closed-loop Fan Speed Control algorithm (FSC) has the capability to
detect aging fans and alert the system. It will likewise detect stalled
or locked fans and trigger an interrupt.

EMC2305 offers a clock output so that multiple devices may be chained
and slaved to the same clock source for optimal performance in large
distributed systems.

Patch set includes:
Patch#1 - add support for EMC2301/2/3/5 RPM-based PWM Fan Speed Controller.
Patch#2 - add microchip,emc2306.yaml
Patch#3 - add emc2305.rst into docs.

Michael Shych (3):
  hwmon: (emc2305) add support for EMC2301/2/3/5 RPM-based PWM Fan Speed
    Controller.
  dt-bindings: hwmon: add microchip,emc2306.yaml dt binding description.
  docs: hwmon: add emc2305.rst to docs

 .../bindings/hwmon/microchip,emc2305.yaml          |  55 ++
 Documentation/hwmon/emc2305.rst                    |  40 ++
 drivers/hwmon/Kconfig                              |  13 +
 drivers/hwmon/Makefile                             |   1 +
 drivers/hwmon/emc2305.c                            | 629 +++++++++++++++++++++
 5 files changed, 738 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwmon/microchip,emc2305.yaml
 create mode 100644 Documentation/hwmon/emc2305.rst
 create mode 100644 drivers/hwmon/emc2305.c

> -----Original Message-----
> From: Guenter Roeck <groeck7@gmail.com> On Behalf Of Guenter Roeck
> Sent: Saturday, April 30, 2022 3:57 PM
> To: Michael Shych <michaelsh@nvidia.com>
> Cc: robh+dt@kernel.org; linux-hwmon@vger.kernel.org;
> devicetree@vger.kernel.org; Vadim Pasternak <vadimp@nvidia.com>
> Subject: Re: [PATCH v1 1/3] hwmon: (emc2305) add support for
> EMC2301/2/3/5 RPM-based PWM Fan Speed Controller.
> 
> On Sat, Apr 30, 2022 at 02:49:03PM +0300, michaelsh@nvidia.com wrote:
> > From: Michael Shych <michaelsh@nvidia.com>
> >
> > Add driver for Microchip EMC2301/2/3/5 RPM-based PWM Fan Speed
> Controller.
> > Modify Makefile and Kconfig to support Microchip EMC2305 RPM-based
> PWM
> > Fan Speed Controller.
> >
> > Signed-off-by: Michael Shych <michaelsh@nvidia.com>
> > Reviewed-by: Vadim Pasternak <vadimp@nvidia.com>
> > ---
> >  drivers/hwmon/Kconfig   |  13 +
> >  drivers/hwmon/Makefile  |   1 +
> >  drivers/hwmon/emc2305.c | 629
> > ++++++++++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 643 insertions(+)
> >  create mode 100644 drivers/hwmon/emc2305.c
> >
> > diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig index
> > 85c22bba439b..3c25ba0e6ef7 100644
> > --- a/drivers/hwmon/Kconfig
> > +++ b/drivers/hwmon/Kconfig
> > @@ -1750,6 +1750,19 @@ config SENSORS_EMC2103
> >  	  This driver can also be built as a module. If so, the module
> >  	  will be called emc2103.
> >
> > +config SENSORS_EMC2305
> > +	tristate "Microchip EMC2305 and compatible EMC2301/2/3"
> > +	depends on I2C
> > +	imply THERMAL
> > +	help
> > +	  If you say yes here you get support for the Microchip EMC2305
> > +	  fan controller chips.
> > +	  The Microchip EMC2305 is a fan controller for up to 5 fans.
> > +	  Fan rotation speeds are reported in RPM.
> > +
> > +	  This driver can also be built as a module.  If so, the module
> > +	  will be called emc2305.
> > +
> >  config SENSORS_EMC6W201
> >  	tristate "SMSC EMC6W201"
> >  	depends on I2C
> > diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile index
> > 93f2b774cc5e..e2238c207ef4 100644
> > --- a/drivers/hwmon/Makefile
> > +++ b/drivers/hwmon/Makefile
> > @@ -70,6 +70,7 @@ obj-$(CONFIG_SENSORS_DS620)	+= ds620.o
> >  obj-$(CONFIG_SENSORS_DS1621)	+= ds1621.o
> >  obj-$(CONFIG_SENSORS_EMC1403)	+= emc1403.o
> >  obj-$(CONFIG_SENSORS_EMC2103)	+= emc2103.o
> > +obj-$(CONFIG_SENSORS_EMC2305)	+= emc2305.o
> >  obj-$(CONFIG_SENSORS_EMC6W201)	+= emc6w201.o
> >  obj-$(CONFIG_SENSORS_F71805F)	+= f71805f.o
> >  obj-$(CONFIG_SENSORS_F71882FG)	+= f71882fg.o
> > diff --git a/drivers/hwmon/emc2305.c b/drivers/hwmon/emc2305.c new
> > file mode 100644 index 000000000000..5c896fdfc525
> > --- /dev/null
> > +++ b/drivers/hwmon/emc2305.c
> > @@ -0,0 +1,629 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * Hardware monitoring driver for EMC2305 fan controller
> > + *
> > + * Copyright (C) 2022 Nvidia Technologies Ltd and Delta Networks, Inc.
> > + */
> > +
> > +#include <linux/err.h>
> > +#include <linux/hwmon.h>
> > +#include <linux/hwmon-sysfs.h>
> 
> Not necessary
Removed.

> 
> > +#include <linux/i2c.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/thermal.h>
> > +#include <linux/version.h>
> > +
> > +static const unsigned short
> > +emc2305_normal_i2c[] = { 0x27, 0x2c, 0x2d, 0x2e, 0x2f, 0x4c, 0x4d,
> > +I2C_CLIENT_END };
> > +
> > +#define EMC2305_REG_DRIVE_FAIL_STATUS	0x27
> > +#define EMC2305_REG_DEVICE		0xfd
> > +#define EMC2305_REG_VENDOR		0xfe
> > +#define EMC2305_FAN_MAX			0xff
> > +#define EMC2305_FAN_MIN			0x00
> > +#define EMC2305_FAN_MAX_STATE		10
> > +#define EMC2305_DEVICE			0x34
> > +#define EMC2305_VENDOR			0x5d
> > +#define EMC2305_REG_PRODUCT_ID		0xfd
> > +#define EMC2305_TACH_REGS_UNUSE_BITS	3
> > +#define EMC2305_TACH_CNT_MULTIPLIER	0x02
> > +#define EMC2305_PWM_MAX			5
> > +#define EMC2305_PWM_CHNL_CMN		0
> > +
> > +#define EMC2305_PWM_DUTY2STATE(duty, max_state, pwm_max) \
> > +	(DIV_ROUND_CLOSEST((duty) * (max_state), (pwm_max))) #define
> > +EMC2305_PWM_STATE2DUTY(state, max_state, pwm_max) \
> > +	(DIV_ROUND_CLOSEST((state) * (pwm_max), (max_state)))
> > +
> > +/* Factor by equations [2] and [3] from data sheet; valid for fans
> > +where the number of edges
> > + * equal (poles * 2 + 1).
> > + */
> 
> /*
>  * Please use standard multi-line comments.
>  */
Ack.

> 
> > +#define EMC2305_RPM_FACTOR		3932160
> > +
> > +#define EMC2305_REG_FAN_DRIVE(n) (0x30 + 0x10 * (n)) #define
> > +EMC2305_REG_FAN_MIN_DRIVE(n) (0x38 + 0x10 * (n)) #define
> > +EMC2305_REG_FAN_TACH(n) (0x3e + 0x10 * (n))
> 
> Please use
> 
> #define<space>NAME<tab>value
>
Ack.

> > +
> > +enum emc230x_product_id {
> > +	EMC2305 = 0x34,
> > +	EMC2303 = 0x35,
> > +	EMC2302 = 0x36,
> > +	EMC2301 = 0x37,
> > +};
> > +
> > +static const struct i2c_device_id emc2305_ids[] = {
> > +	{ "emc2305", 0 },
> > +	{ "emc2303", 0 },
> > +	{ "emc2302", 0 },
> > +	{ "emc2301", 0 },
> > +	{ }
> > +};
> > +MODULE_DEVICE_TABLE(i2c, emc2305_ids);
> > +
> > +static const struct of_device_id emc2305_dt_ids[] = {
> > +	{ .compatible = "smsc,emc2305" },
> > +	{ }
> > +};
> > +MODULE_DEVICE_TABLE(of, emc2305_dt_ids);
> > +
> > +/**
> > + * @cdev: cooling device;
> > + * @curr_state: cooling current state;
> > + * @last_hwmon_state: last cooling state updated by hwmon subsystem;
> > + * @last_thermal_state: last cooling state updated by thermal
> > +subsystem;
> > + *
> > + * The 'last_hwmon_state' and 'last_thermal_state' fields are
> > +provided to support fan low limit
> > + * speed feature. The purpose of this feature is to provides ability
> > +to limit fan speed
> > + * according to some system wise considerations, like absence of some
> > +replaceable units (PSU or
> > + * line cards), high system ambient temperature, unreliable
> > +transceivers temperature sensing or
> > + * some other factors which indirectly impacts system's airflow
> > + * Fan low limit feature is supported through 'hwmon' interface:
> > +'hwmon' 'pwm' attribute is
> > + * used for setting low limit for fan speed in case 'thermal'
> > +subsystem is configured in
> > + * kernel. In this case setting fan speed through 'hwmon' will never let the
> 'thermal'
> > + * subsystem to select a lower duty cycle than the duty cycle selected with
> the 'pwm'
> > + * attribute.
> > + * From other side, fan speed is to be updated in hardware through
> > +'pwm' only in case the
> > + * requested fan speed is above last speed set by 'thermal'
> > +subsystem, otherwise requested fan
> > + * speed will be just stored with no PWM update.
> > + */
> > +struct emc2305_cdev_data {
> > +	struct thermal_cooling_device *cdev;
> > +	unsigned int cur_state;
> > +	unsigned long last_hwmon_state;
> > +	unsigned long last_thermal_state;
> > +};
> > +
> > +/**
> > + * @client: i2c client;
> > + * @hwmon_dev: hwmon device;
> > + * @max_state: maximum cooling state of the cooling device;
> > + * @pwm_max: maximum PWM;
> > + * @pwm_min: minimum PWM;
> > + * @pwm_channel: maximum number of PWM channels;
> > + * @cdev_data: array of cooling devices data;  */ struct emc2305_data
> > +{
> > +	struct i2c_client *client;
> > +	struct device *hwmon_dev;
> > +	u8 max_state;
> > +	u8 pwm_max;
> > +	u8 pwm_min;
> > +	u8 pwm_num;
> > +	u8 pwm_channel;
> > +	struct emc2305_cdev_data cdev_data[EMC2305_PWM_MAX]; };
> > +
> > +static char *emc2305_fan_name[] = {
> > +	"emc2305_fan",
> > +	"emc2305_fan1",
> > +	"emc2305_fan2",
> > +	"emc2305_fan3",
> > +	"emc2305_fan4",
> > +	"emc2305_fan5",
> > +};
> > +
> > +static int emc2305_get_max_channel(struct emc2305_data *data) {
> > +	if (data->pwm_channel == EMC2305_PWM_CHNL_CMN)
> > +		return data->pwm_num;
> > +	else
> 
> else after return is unnecessary
Changed.

> 
> > +		return data->pwm_channel;
> > +}
> > +
> > +static int emc2305_get_cdev_idx(struct thermal_cooling_device *cdev)
> > +{
> > +	struct emc2305_data *data = cdev->devdata;
> > +	size_t len = strlen(cdev->type);
> > +	int ret;
> > +
> > +	if (len <= 0)
> > +		return -EINVAL;
> > +
> > +	/* Retuns index of cooling device 0..4 in case of separate PWM
> setting.
> > +	 * Zero index is used in case of one common PWM setting.
> > +	 * If the mode is set as EMC2305_PWM_CHNL_CMN, all PWMs are to
> be bound
> > +	 * to the common thermal zone and should work at the same speed
> > +	 * to perform cooling for the same thermal junction.
> > +	 * Otherwise, return specific channel that will be used in bound
> > +	 * related PWM to the thermal zone.
> > +	 */
> > +	if (data->pwm_channel == EMC2305_PWM_CHNL_CMN)
> > +		return 0;
> > +
> > +	ret = cdev->type[len - 1];
> > +	switch (ret) {
> > +	case '1' ... '5':
> > +		return ret - '1';
> > +	default:
> > +		break;
> > +	}
> > +	return -EINVAL;
> > +}
> > +
> > +static int emc2305_get_cur_state(struct thermal_cooling_device *cdev,
> > +unsigned long *state) {
> > +	int cdev_idx;
> > +	struct emc2305_data *data = cdev->devdata;
> > +
> > +	cdev_idx = emc2305_get_cdev_idx(cdev);
> > +	if (cdev_idx < 0)
> > +		return cdev_idx;
> > +
> > +	*state = data->cdev_data[cdev_idx].cur_state;
> > +	return 0;
> > +}
> > +
> > +static int emc2305_get_max_state(struct thermal_cooling_device *cdev,
> > +unsigned long *state) {
> > +	struct emc2305_data *data = cdev->devdata;
> > +	*state = data->max_state;
> > +	return 0;
> > +}
> > +
> > +static int emc2305_set_cur_state(struct thermal_cooling_device *cdev,
> > +unsigned long state) {
> > +	int cdev_idx;
> > +	struct emc2305_data *data = cdev->devdata;
> > +	struct i2c_client *client = data->client;
> > +	u8 val, i;
> > +
> > +	if (state > data->max_state)
> > +		return -EINVAL;
> > +
> > +	cdev_idx =  emc2305_get_cdev_idx(cdev);
> > +	if (cdev_idx < 0)
> > +		return cdev_idx;
> > +
> > +	/* Save thermal state. */
> > +	data->cdev_data[cdev_idx].last_thermal_state = state;
> > +	state = max_t(unsigned long, state,
> > +data->cdev_data[cdev_idx].last_hwmon_state);
> > +
> > +	val = EMC2305_PWM_STATE2DUTY(state, data->max_state, data-
> >pwm_max);
> > +	if (val > EMC2305_FAN_MAX)
> > +		return -EINVAL;
> > +
> > +	data->cdev_data[cdev_idx].cur_state = state;
> > +	if (data->pwm_channel == EMC2305_PWM_CHNL_CMN)
> > +	/* Set the same PWM value in all channels
> > +	 * if common PWM channel is used.
> > +	 */
> > +		for (i = 0; i < data->pwm_num; i++)
> > +			i2c_smbus_write_byte_data(client,
> EMC2305_REG_FAN_DRIVE(i), val);
> > +	else
> > +		i2c_smbus_write_byte_data(client,
> EMC2305_REG_FAN_DRIVE(cdev_idx),
> > +val);
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct thermal_cooling_device_ops emc2305_cooling_ops = {
> > +	.get_max_state = emc2305_get_max_state,
> > +	.get_cur_state = emc2305_get_cur_state,
> > +	.set_cur_state = emc2305_set_cur_state, };
> > +
> > +static int emc2305_show_fault(struct device *dev, int channel) {
> > +	struct emc2305_data *data = dev_get_drvdata(dev);
> > +	struct i2c_client *client = data->client;
> > +	int status_reg;
> > +
> > +	status_reg = i2c_smbus_read_byte_data(client,
> EMC2305_REG_DRIVE_FAIL_STATUS);
> > +	return status_reg & (1 << channel) ? 1 : 0; }
> > +
> > +static int emc2305_show_fan(struct device *dev, int channel) {
> > +	struct emc2305_data *data = dev_get_drvdata(dev);
> > +	struct i2c_client *client = data->client;
> > +	int ret;
> > +
> > +	ret = i2c_smbus_read_word_swapped(client,
> EMC2305_REG_FAN_TACH(channel));
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	ret = ret >> EMC2305_TACH_REGS_UNUSE_BITS;
> > +	return EMC2305_RPM_FACTOR * EMC2305_TACH_CNT_MULTIPLIER
> / (ret > 0 ?
> > +ret : 1); }
> > +
> > +static int emc2305_show_pwm(struct device *dev, int channel) {
> > +	struct emc2305_data *data = dev_get_drvdata(dev);
> > +	struct i2c_client *client = data->client;
> > +
> > +	return i2c_smbus_read_byte_data(client,
> > +EMC2305_REG_FAN_DRIVE(channel)); }
> > +
> > +static int emc2305_set_pwm(struct device *dev, long val, int channel)
> > +{
> > +	struct emc2305_data *data = dev_get_drvdata(dev);
> > +	struct i2c_client *client = data->client;
> > +
> > +	if (val < data->pwm_min || val > data->pwm_max)
> > +		return -EINVAL;
> > +
> > +	i2c_smbus_write_byte_data(client,
> EMC2305_REG_FAN_DRIVE(channel), val);
> > +	data->cdev_data[channel].cur_state =
> EMC2305_PWM_DUTY2STATE(val, data->max_state,
> > +								    data-
> >pwm_max);
> > +	return 0;
> > +}
> > +
> > +static int emc2305_get_tz_of(struct device *dev) {
> > +	struct device_node *np = dev->of_node;
> > +	struct emc2305_data *data = dev_get_drvdata(dev);
> > +	int ret = 0;
> > +
> > +	/* OF parameters are optional - overwrite default setting
> > +	 * if some of them are provided.
> > +	 */
> > +
> > +	if (of_find_property(np, "emc2305,cooling-levels", NULL)) {
> > +		ret = of_property_read_u8(np, "emc2305,cooling-levels",
> &data->max_state);
> > +		if (ret)
> > +			return ret;
> > +	}
> > +
> > +	if (of_find_property(np, "emc2305,pwm-max", NULL)) {
> > +		ret = of_property_read_u8(np, "emc2305,pwm-max", &data-
> >pwm_max);
> > +		if (ret)
> > +			return ret;
> > +	}
> > +
> > +	if (of_find_property(np, "emc2305,pwm-min", NULL)) {
> > +		ret = of_property_read_u8(np, "emc2305,pwm-min", &data-
> >pwm_min);
> > +		if (ret)
> > +			return ret;
> > +	}
> > +
> > +	/* Not defined or 0 means one thermal zone over all colling devices.
> 
> cooling
Changed.

> 
> > +	 * Otherwise - separted thermal zones for each PWM channel.
> 
> separate ?
> 
> > +	 */
> > +	if (of_find_property(np, "emc2305,pwm-channel", NULL)) {
> > +		ret = of_property_read_u8(np, "emc2305,pwm-channel",
> &data->pwm_channel);
> > +		if (ret)
> > +			return ret;
> > +	}
> 
> I think those values should be validated.
Checks are added.

> 
> > +
> > +	return ret;
> > +}
> > +
> > +static int emc2305_set_single_tz(struct device *dev, int idx) {
> > +	struct emc2305_data *data = dev_get_drvdata(dev);
> > +	long pwm = data->pwm_max;
> > +	int cdev_idx;
> > +
> > +	cdev_idx = (idx) ? idx - 1 : 0;
> > +
> > +	if (dev->of_node)
> > +		data->cdev_data[cdev_idx].cdev =
> > +			devm_thermal_of_cooling_device_register(dev, dev-
> >of_node,
> > +
> 	emc2305_fan_name[idx], data,
> > +
> 	&emc2305_cooling_ops);
> > +	else
> > +		data->cdev_data[cdev_idx].cdev =
> > +
> 	thermal_cooling_device_register(emc2305_fan_name[idx], data,
> > +
> 	&emc2305_cooling_ops);
> > +
> > +	if (IS_ERR(data->cdev_data[cdev_idx].cdev)) {
> > +		dev_err(dev, "Failed to register cooling device %s\n",
> emc2305_fan_name[idx]);
> > +		return PTR_ERR(data->cdev_data[cdev_idx].cdev);
> > +	}
> > +	emc2305_set_pwm(dev, pwm, cdev_idx);
> > +	data->cdev_data[cdev_idx].cur_state = data->max_state;
> > +	/* Set minimal PWM speed. */
> > +	data->cdev_data[cdev_idx].last_hwmon_state =
> EMC2305_PWM_DUTY2STATE(data->pwm_min,
> > +
> data->max_state,
> > +
> data->pwm_max);
> > +	return 0;
> > +}
> > +
> > +static int emc2305_set_tz(struct device *dev) {
> > +	struct emc2305_data *data = dev_get_drvdata(dev);
> > +	int i, ret;
> > +
> > +	if (data->pwm_channel == EMC2305_PWM_CHNL_CMN)
> > +		return emc2305_set_single_tz(dev, 0);
> > +
> > +	for (i = 0; i < data->pwm_channel; i++) {
> > +		ret = emc2305_set_single_tz(dev, i + 1);
> > +		if (ret)
> > +			goto thermal_cooling_device_register_fail;
> > +	}
> > +	return 0;
> > +
> > +thermal_cooling_device_register_fail:
> > +	emc2305_unset_tz(dev);
> > +	return ret;
> > +}
> > +
> > +static void emc2305_unset_tz(struct device *dev) {
> > +	struct emc2305_data *data = dev_get_drvdata(dev);
> > +	int i;
> > +
> > +	/* Unregister cooling device in case they have been registered by
> > +	 * thermal_cooling_device_unregister(). No need for clean-up flow in
> case they
> > +	 * have been registered by
> devm_thermal_of_cooling_device_register()
> > +	 */
> > +	if (!dev->of_node) {
> > +		for (i = 0; i < EMC2305_PWM_MAX; i++)
> > +			if (data->cdev_data[i].cdev)
> > +				thermal_cooling_device_unregister(data-
> >cdev_data[i].cdev);
> > +	}
> > +}
> > +
> > +static umode_t
> > +emc2305_is_visible(const void *data, enum hwmon_sensor_types type,
> > +u32 attr, int channel) {
> > +	int max_channel = emc2305_get_max_channel((struct emc2305_data
> > +*)data);
> 
> Unnecessary typecast.
It's required as otherwise there is compilation warning.

> 
> > +
> > +	/* Don't show channels which are not physically connected. */
> > +	if ((channel + 1) > max_channel)
> 
> Unnecessary ()
> 
Removed

> > +		return 0;
> > +	switch (type) {
> > +	case hwmon_fan:
> > +		switch (attr) {
> > +		case hwmon_fan_input:
> > +			return 0444;
> > +		case hwmon_fan_fault:
> > +			return 0444;
> > +		default:
> > +			break;
> > +		}
> > +		break;
> > +	case hwmon_pwm:
> > +		switch (attr) {
> > +		case hwmon_pwm_input:
> > +			return 0644;
> > +		default:
> > +			break;
> > +		}
> > +		break;
> > +	default:
> > +		break;
> > +	}
> > +
> > +	return 0;
> > +};
> > +
> > +static int
> > +emc2305_write(struct device *dev, enum hwmon_sensor_types type, u32
> > +attr, int channel, long val) {
> > +	struct emc2305_data *data = dev_get_drvdata(dev);
> > +
> > +	switch (type) {
> > +	case hwmon_pwm:
> > +		switch (attr) {
> > +		case hwmon_pwm_input:
> > +			/* If thermal is configured - handle PWM limit setting.
> */
> > +			if (IS_REACHABLE(CONFIG_THERMAL)) {
> > +				data->cdev_data[channel].last_hwmon_state
> =
> > +					EMC2305_PWM_DUTY2STATE(val,
> data->max_state, data->pwm_max);
> > +				/* Update PWM only in case requested state
> is not less than the
> > +				 * last thermal state.
> > +				 */
> > +				if (data-
> >cdev_data[channel].last_hwmon_state >=
> > +				    data-
> >cdev_data[channel].last_thermal_state)
> > +					return emc2305_set_cur_state(data-
> >cdev_data[channel].cdev,
> > +							data-
> >cdev_data[channel].last_hwmon_state);
> > +				return 0;
> > +			}
> > +			return emc2305_set_pwm(dev, val, channel);
> > +		default:
> > +			break;
> > +		}
> > +		break;
> > +	default:
> > +		break;
> > +	}
> > +
> > +	return -EOPNOTSUPP;
> > +};
> > +
> > +static int
> > +emc2305_read(struct device *dev, enum hwmon_sensor_types type, u32
> > +attr, int channel, long *val) {
> > +	int ret;
> > +
> > +	switch (type) {
> > +	case hwmon_fan:
> > +		switch (attr) {
> > +		case hwmon_fan_input:
> > +			ret = emc2305_show_fan(dev, channel);
> > +			if (ret < 0)
> > +				return ret;
> > +			*val = ret;
> > +			return 0;
> > +		case hwmon_fan_fault:
> > +			ret = emc2305_show_fault(dev, channel);
> > +			if (ret < 0)
> > +				return ret;
> > +			*val = ret;
> > +			return 0;
> > +		default:
> > +			break;
> > +		}
> > +		break;
> > +	case hwmon_pwm:
> > +		switch (attr) {
> > +		case hwmon_pwm_input:
> > +			ret = emc2305_show_pwm(dev, channel);
> > +			if (ret < 0)
> > +				return ret;
> > +			*val = ret;
> > +			return 0;
> > +		default:
> > +			break;
> > +		}
> > +		break;
> > +	default:
> > +		break;
> > +	}
> > +
> > +	return -EOPNOTSUPP;
> > +};
> > +
> > +static const struct hwmon_ops emc2305_ops = {
> > +	.is_visible = emc2305_is_visible,
> > +	.read = emc2305_read,
> > +	.write = emc2305_write,
> > +};
> > +
> > +static const struct hwmon_channel_info *emc2305_info[] = {
> > +	HWMON_CHANNEL_INFO(fan,
> > +			   HWMON_F_INPUT | HWMON_F_FAULT,
> > +			   HWMON_F_INPUT | HWMON_F_FAULT,
> > +			   HWMON_F_INPUT | HWMON_F_FAULT,
> > +			   HWMON_F_INPUT | HWMON_F_FAULT,
> > +			   HWMON_F_INPUT | HWMON_F_FAULT),
> > +	HWMON_CHANNEL_INFO(pwm,
> > +			   HWMON_PWM_INPUT,
> > +			   HWMON_PWM_INPUT,
> > +			   HWMON_PWM_INPUT,
> > +			   HWMON_PWM_INPUT,
> > +			   HWMON_PWM_INPUT),
> > +	NULL
> > +};
> > +
> > +static const struct hwmon_chip_info emc2305_chip_info = {
> > +	.ops = &emc2305_ops,
> > +	.info = emc2305_info,
> > +};
> > +
> > +static int emc2305_identify(struct device *dev) {
> > +	struct i2c_client *client = to_i2c_client(dev);
> > +	struct emc2305_data *data = i2c_get_clientdata(client);
> > +	int ret;
> > +
> > +	ret = i2c_smbus_read_byte_data(client,
> EMC2305_REG_PRODUCT_ID);
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	switch (ret) {
> > +	case EMC2305:
> > +		data->pwm_num = 5;
> > +		break;
> > +	case EMC2303:
> > +		data->pwm_num = 3;
> > +		break;
> > +	case EMC2302:
> > +		data->pwm_num = 2;
> > +		break;
> > +	case EMC2301:
> > +		data->pwm_num = 1;
> > +		break;
> > +	default:
> > +		return -EINVAL;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static int emc2305_probe(struct i2c_client *client, const struct
> > +i2c_device_id *id) {
> > +	struct i2c_adapter *adapter = client->adapter;
> > +	struct device *dev = &client->dev;
> > +	struct emc2305_data *data;
> > +	int vendor, device;
> > +	int ret;
> > +	int i;
> > +
> > +	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
> I2C_FUNC_SMBUS_WORD_DATA))
> > +		return -ENODEV;
> > +
> > +	vendor = i2c_smbus_read_byte_data(client,
> EMC2305_REG_VENDOR);
> > +	if (vendor != EMC2305_VENDOR)
> > +		return -ENODEV;
> > +
> > +	device = i2c_smbus_read_byte_data(client, EMC2305_REG_DEVICE);
> > +	if (device != EMC2305_DEVICE)
> > +		return -ENODEV;
> > +
> > +	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> > +	if (!data)
> > +		return -ENOMEM;
> > +
> > +	i2c_set_clientdata(client, data);
> > +	data->client = client;
> > +
> > +	ret = emc2305_identify(dev);
> > +	if (ret)
> > +		return ret;
> > +
> > +	data->max_state = EMC2305_FAN_MAX_STATE;
> > +	data->pwm_max = EMC2305_FAN_MAX;
> > +	data->pwm_min = EMC2305_FAN_MIN;
> > +	data->pwm_channel = EMC2305_PWM_CHNL_CMN;
> > +	if (dev->of_node) {
> > +		ret = emc2305_get_tz_of(dev);
> > +		if (ret < 0)
> > +			return ret;
> > +	}
> > +
> > +	data->hwmon_dev = devm_hwmon_device_register_with_info(dev,
> "emc2305", data,
> > +
> &emc2305_chip_info, NULL);
> > +	if (IS_ERR(data->hwmon_dev))
> > +		return PTR_ERR(data->hwmon_dev);
> > +
> > +	if (IS_REACHABLE(CONFIG_THERMAL)) {
> > +		ret = emc2305_set_tz(dev);
> > +		if (ret != 0)
> > +			return ret;
> > +	}
> > +
> > +	for (i = 0; i < data->pwm_num; i++)
> > +		i2c_smbus_write_byte_data(client,
> EMC2305_REG_FAN_MIN_DRIVE(i),
> > +data->pwm_min);
> > +
> > +	return 0;
> > +}
> > +
> > +static int emc2305_remove(struct i2c_client *client) {
> > +	struct device *dev = &client->dev;
> > +
> > +	if (IS_REACHABLE(CONFIG_THERMAL))
> > +		emc2305_unset_tz(dev);
> 
> It would be desirable to handle this with devm_add_action_or_reset() from
> emc2305_set_tz().
>
It's not required in case of devm_thermal_of_cooling_device_register
Added comment.
 
> > +	return 0;
> > +}
> > +
> > +static struct i2c_driver emc2305_driver = {
> > +	.class  = I2C_CLASS_HWMON,
> > +	.driver = {
> > +		.name = "emc2305",
> > +		.of_match_table = emc2305_dt_ids,
> > +	},
> > +	.probe    = emc2305_probe,
> > +	.remove	  = emc2305_remove,
> > +	.id_table = emc2305_ids,
> > +	.address_list = emc2305_normal_i2c,
> > +};
> > +
> > +module_i2c_driver(emc2305_driver);
> > +
> > +MODULE_AUTHOR("Nvidia");
> > +MODULE_DESCRIPTION("Microchip EMC2305 fan controller driver");
> > +MODULE_LICENSE("GPL");
> > --
> > 2.14.1
> >


Thank you,
    Michael.