diff mbox series

[v2,2/2] platform/x86: dell: Add new dell-wmi-ddv driver

Message ID 20220927204521.601887-3-W_Armin@gmx.de
State Accepted
Commit a77272c16041862c5c8d450c8701139887e1bb05
Headers show
Series platform/x86: dell: Add new dell-wmi-ddv driver | expand

Commit Message

Armin Wolf Sept. 27, 2022, 8:45 p.m. UTC
The dell-wmi-ddv driver adds support for reading
the current temperature and ePPID of ACPI batteries
on supported Dell machines.

Since the WMI interface used by this driver does not
do any input validation and thus cannot be used for probing,
the driver depends on the ACPI battery extension machanism
to discover batteries.

The driver also supports a debugfs interface for retrieving
buffers containing fan and thermal sensor information.
Since the meaing of the content of those buffers is currently
unknown, the interface is meant for reverse-engineering and
will likely be replaced with an hwmon interface once the
meaning has been understood.

The driver was tested on a Dell Inspiron 3505.

Signed-off-by: Armin Wolf <W_Armin@gmx.de>
---
 .../ABI/testing/debugfs-dell-wmi-ddv          |  21 +
 .../ABI/testing/sysfs-platform-dell-wmi-ddv   |   7 +
 MAINTAINERS                                   |   7 +
 drivers/platform/x86/dell/Kconfig             |  13 +
 drivers/platform/x86/dell/Makefile            |   1 +
 drivers/platform/x86/dell/dell-wmi-ddv.c      | 361 ++++++++++++++++++
 drivers/platform/x86/wmi.c                    |   1 +
 7 files changed, 411 insertions(+)
 create mode 100644 Documentation/ABI/testing/debugfs-dell-wmi-ddv
 create mode 100644 Documentation/ABI/testing/sysfs-platform-dell-wmi-ddv
 create mode 100644 drivers/platform/x86/dell/dell-wmi-ddv.c

--
2.30.2

Comments

Andy Shevchenko Sept. 29, 2022, 9:51 a.m. UTC | #1
On Wed, Sep 28, 2022 at 10:57:16PM +0200, Armin Wolf wrote:
> Am 28.09.22 um 12:47 schrieb Andy Shevchenko:
> > On Tue, Sep 27, 2022 at 10:45:21PM +0200, Armin Wolf wrote:

Side note: When answering to emails, please remove unrelated context, do not
make this the answering party problem.
Armin Wolf Oct. 21, 2022, 9:34 a.m. UTC | #2
Am 29.09.22 um 15:12 schrieb Hans de Goede:

> Hi,
>
> On 9/29/22 11:50, Andy Shevchenko wrote:
>> On Wed, Sep 28, 2022 at 10:57:16PM +0200, Armin Wolf wrote:
>>> Am 28.09.22 um 12:47 schrieb Andy Shevchenko:
>>>> On Tue, Sep 27, 2022 at 10:45:21PM +0200, Armin Wolf wrote:
>> ...
>>
>>>>> +static void dell_wmi_ddv_debugfs_init(struct wmi_device *wdev)
>>>> Strictly speaking this should return int (see below).
>>>>
>>>>> +{
>>>>> +	struct dentry *entry;
>>>>> +	char name[64];
>>>>> +Fujitsu Academy
>>>>>
>>>>> +	scnprintf(name, ARRAY_SIZE(name), "%s-%s", DRIVER_NAME, dev_name(&wdev->dev));
>>>>> +	entry = debugfs_create_dir(name, NULL);
>>>>> +
>>>>> +	debugfs_create_devm_seqfile(&wdev->dev, "fan_sensor_information", entry,
>>>>> +				    dell_wmi_ddv_fan_read);
>>>>> +	debugfs_create_devm_seqfile(&wdev->dev, "thermal_sensor_information", entry,
>>>>> +				    dell_wmi_ddv_temp_read);
>>>>> +
>>>>> +	devm_add_action_or_reset(&wdev->dev, dell_wmi_ddv_debugfs_remove, entry);
>>>> return devm...
>>>>
>>>> This is not related to debugfs and there is no rule to avoid checking error
>>>> codes from devm_add_action_or_reset().
>>>>
>>> According to the documentation of debugfs_create_dir(), drivers should work fine if debugfs
>>> initialization fails. Thus the the return value of dell_wmi_ddv_debugfs_init() would be ignored
>>> when called, which means that returning an error would serve no purpose.
>>> Additionally, devm_add_action_or_reset() automatically executes the cleanup function if devres
>>> registration fails, so we do not have to care about that.
>> The problem with your code that if devm_ call fails and you ain't stop probing
>> the remove-insert module (or unbind-bind) cycle will fail, because of existing
>> (leaked) debugfs dentries.
> No it won't if the devm_ call fails then it will directly call
> the passed in handler so in this case we can simply continue
> without debugfs entries (which will have been removed by the
> handler). The directly calling of the action handler on
> failure is the whole difference between devm_add_action()
> and devm_add_action_or_reset()
>
> So using it this way in the case of a debugfs init function
> is fine.
>
>>>>> +		.name = DRIVER_NAME,
>>>> I would use explicit literal since this is a (semi-) ABI, and having it as
>>>> a define feels not fully right.
>>> The driver name is used in two places (init and debugfs), so having a define for it
>>> avoids problems in case someone forgets to change both.
>> Which is exactly what we must prevent developer to do. If changing debugfs it
>> mustn't change the driver name, because the latter is ABI, while the former is
>> not.
> Arguably both are not really ABI. Drivers have been renamed in the past
> without issues for userspace.
>
> Regards,
>
> Hans
>
What is the current status of this patch set? If necessary, i can submit an v3 patch set which includes the
patch regarding the minor style fixes. I also tested the driver on my Dell Insprion 3505 for some time, so
i can proof it works.

Armin Wolf
Hans de Goede Oct. 21, 2022, 9:58 a.m. UTC | #3
Hi Armin, Rafael,

On 10/21/22 11:34, Armin Wolf wrote:
> Am 29.09.22 um 15:12 schrieb Hans de Goede:
> 
>> Hi,
>>
>> On 9/29/22 11:50, Andy Shevchenko wrote:
>>> On Wed, Sep 28, 2022 at 10:57:16PM +0200, Armin Wolf wrote:
>>>> Am 28.09.22 um 12:47 schrieb Andy Shevchenko:
>>>>> On Tue, Sep 27, 2022 at 10:45:21PM +0200, Armin Wolf wrote:
>>> ...
>>>
>>>>>> +static void dell_wmi_ddv_debugfs_init(struct wmi_device *wdev)
>>>>> Strictly speaking this should return int (see below).
>>>>>
>>>>>> +{
>>>>>> +    struct dentry *entry;
>>>>>> +    char name[64];
>>>>>> +Fujitsu Academy
>>>>>>
>>>>>> +    scnprintf(name, ARRAY_SIZE(name), "%s-%s", DRIVER_NAME, dev_name(&wdev->dev));
>>>>>> +    entry = debugfs_create_dir(name, NULL);
>>>>>> +
>>>>>> +    debugfs_create_devm_seqfile(&wdev->dev, "fan_sensor_information", entry,
>>>>>> +                    dell_wmi_ddv_fan_read);
>>>>>> +    debugfs_create_devm_seqfile(&wdev->dev, "thermal_sensor_information", entry,
>>>>>> +                    dell_wmi_ddv_temp_read);
>>>>>> +
>>>>>> +    devm_add_action_or_reset(&wdev->dev, dell_wmi_ddv_debugfs_remove, entry);
>>>>> return devm...
>>>>>
>>>>> This is not related to debugfs and there is no rule to avoid checking error
>>>>> codes from devm_add_action_or_reset().
>>>>>
>>>> According to the documentation of debugfs_create_dir(), drivers should work fine if debugfs
>>>> initialization fails. Thus the the return value of dell_wmi_ddv_debugfs_init() would be ignored
>>>> when called, which means that returning an error would serve no purpose.
>>>> Additionally, devm_add_action_or_reset() automatically executes the cleanup function if devres
>>>> registration fails, so we do not have to care about that.
>>> The problem with your code that if devm_ call fails and you ain't stop probing
>>> the remove-insert module (or unbind-bind) cycle will fail, because of existing
>>> (leaked) debugfs dentries.
>> No it won't if the devm_ call fails then it will directly call
>> the passed in handler so in this case we can simply continue
>> without debugfs entries (which will have been removed by the
>> handler). The directly calling of the action handler on
>> failure is the whole difference between devm_add_action()
>> and devm_add_action_or_reset()
>>
>> So using it this way in the case of a debugfs init function
>> is fine.
>>
>>>>>> +        .name = DRIVER_NAME,
>>>>> I would use explicit literal since this is a (semi-) ABI, and having it as
>>>>> a define feels not fully right.
>>>> The driver name is used in two places (init and debugfs), so having a define for it
>>>> avoids problems in case someone forgets to change both.
>>> Which is exactly what we must prevent developer to do. If changing debugfs it
>>> mustn't change the driver name, because the latter is ABI, while the former is
>>> not.
>> Arguably both are not really ABI. Drivers have been renamed in the past
>> without issues for userspace.
>>
>> Regards,
>>
>> Hans
>>
> What is the current status of this patch set?

I indicated to Rafael (ACPI subsys maintainer) that I consider this ready
for merging and tried to coordinate this with Rafael, but that email
seems to have fallen through the cracks, likely due to it being pretty
close to the 6.1 merge window. So lets try again:

Rafael, from my pov this patch-set is ready for merging, since 2/2 depends
on "[PATCH v2 1/2] ACPI: battery: Pass battery hook pointer to hook callbacks"
we need to coordinate this.

Since even patch 1/2 mostly touches files under drivers/platform/x86 I would
prefer to merge this through the pdx86 tree, may I have your ack for this ?

> If necessary, i can submit an v3 patch set which includes the
> patch regarding the minor style fixes. I also tested the driver on my Dell Insprion 3505 for some time, so
> i can proof it works.

I can squash the follow up patch into 2/2 when merging this myself. From
my pov no action is needed from you on this at this moment on time. But
it is good that you send a friendly ping about this :)

Regards,

Hans
diff mbox series

Patch

diff --git a/Documentation/ABI/testing/debugfs-dell-wmi-ddv b/Documentation/ABI/testing/debugfs-dell-wmi-ddv
new file mode 100644
index 000000000000..fbcc5d6f7388
--- /dev/null
+++ b/Documentation/ABI/testing/debugfs-dell-wmi-ddv
@@ -0,0 +1,21 @@ 
+What:		/sys/kernel/debug/dell-wmi-ddv-<wmi_device_name>/fan_sensor_information
+Date:		September 2022
+KernelVersion:	6.1
+Contact:	Armin Wolf <W_Armin@gmx.de>
+Description:
+		This file contains the contents of the fan sensor information buffer,
+		which contains fan sensor entries and a terminating character (0xFF).
+
+		Each fan sensor entry consists of three bytes with an unknown meaning,
+		interested people may use this file for reverse-engineering.
+
+What:		/sys/kernel/debug/dell-wmi-ddv-<wmi_device_name>/thermal_sensor_information
+Date:		September 2022
+KernelVersion:	6.1
+Contact:	Armin Wolf <W_Armin@gmx.de>
+Description:
+		This file contains the contents of the thermal sensor information buffer,
+		which contains thermal sensor entries and a terminating character (0xFF).
+
+		Each thermal sensor entry consists of five bytes with an unknown meaning,
+		interested people may use this file for reverse-engineering.
diff --git a/Documentation/ABI/testing/sysfs-platform-dell-wmi-ddv b/Documentation/ABI/testing/sysfs-platform-dell-wmi-ddv
new file mode 100644
index 000000000000..1d97ad615c66
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-platform-dell-wmi-ddv
@@ -0,0 +1,7 @@ 
+What:		/sys/class/power_supply/<battery_name>/eppid
+Date:		September 2022
+KernelVersion:	6.1
+Contact:	Armin Wolf <W_Armin@gmx.de>
+Description:
+		Reports the Dell ePPID (electronic Dell Piece Part Identification)
+		of the ACPI battery.
diff --git a/MAINTAINERS b/MAINTAINERS
index 6bb894ea4a77..d9fd4c9eebbc 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5821,6 +5821,13 @@  L:	Dell.Client.Kernel@dell.com
 S:	Maintained
 F:	drivers/platform/x86/dell/dell-wmi-descriptor.c

+DELL WMI DDV DRIVER
+M:	Armin Wolf <W_Armin@gmx.de>
+S:	Maintained
+F:	Documentation/ABI/testing/debugfs-dell-wmi-ddv
+F:	Documentation/ABI/testing/sysfs-platform-dell-wmi-ddv
+F:	drivers/platform/x86/dell/dell-wmi-ddv.c
+
 DELL WMI SYSMAN DRIVER
 M:	Divya Bharathi <divya.bharathi@dell.com>
 M:	Prasanth Ksr <prasanth.ksr@dell.com>
diff --git a/drivers/platform/x86/dell/Kconfig b/drivers/platform/x86/dell/Kconfig
index 25421e061c47..d319de8f2132 100644
--- a/drivers/platform/x86/dell/Kconfig
+++ b/drivers/platform/x86/dell/Kconfig
@@ -189,6 +189,19 @@  config DELL_WMI_DESCRIPTOR
 	default n
 	depends on ACPI_WMI

+config DELL_WMI_DDV
+	tristate "Dell WMI sensors Support"
+	default m
+	depends on ACPI_BATTERY
+	depends on ACPI_WMI
+	help
+	  This option adds support for WMI-based sensors like
+	  battery temperature sensors found on some Dell notebooks.
+	  It also supports reading of the battery ePPID.
+
+	  To compile this drivers as a module, choose M here: the module will
+	  be called dell-wmi-ddv.
+
 config DELL_WMI_LED
 	tristate "External LED on Dell Business Netbooks"
 	default m
diff --git a/drivers/platform/x86/dell/Makefile b/drivers/platform/x86/dell/Makefile
index ddba1df71e80..1b8942426622 100644
--- a/drivers/platform/x86/dell/Makefile
+++ b/drivers/platform/x86/dell/Makefile
@@ -19,5 +19,6 @@  dell-wmi-objs				:= dell-wmi-base.o
 dell-wmi-$(CONFIG_DELL_WMI_PRIVACY)	+= dell-wmi-privacy.o
 obj-$(CONFIG_DELL_WMI_AIO)		+= dell-wmi-aio.o
 obj-$(CONFIG_DELL_WMI_DESCRIPTOR)	+= dell-wmi-descriptor.o
+obj-$(CONFIG_DELL_WMI_DDV)		+= dell-wmi-ddv.o
 obj-$(CONFIG_DELL_WMI_LED)		+= dell-wmi-led.o
 obj-$(CONFIG_DELL_WMI_SYSMAN)		+= dell-wmi-sysman/
diff --git a/drivers/platform/x86/dell/dell-wmi-ddv.c b/drivers/platform/x86/dell/dell-wmi-ddv.c
new file mode 100644
index 000000000000..6ccce90f475d
--- /dev/null
+++ b/drivers/platform/x86/dell/dell-wmi-ddv.c
@@ -0,0 +1,361 @@ 
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * dell-wmi-ddv.c -- Linux driver for WMI sensor information on Dell notebooks.
+ *
+ * Copyright (C) 2022 Armin Wolf <W_Armin@gmx.de>
+ */
+
+#define pr_format(fmt) KBUILD_MODNAME ": " fmt
+
+#include <acpi/battery.h>
+#include <linux/acpi.h>
+#include <linux/debugfs.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/kstrtox.h>
+#include <linux/math.h>
+#include <linux/module.h>
+#include <linux/limits.h>
+#include <linux/power_supply.h>
+#include <linux/seq_file.h>
+#include <linux/sysfs.h>
+#include <linux/wmi.h>
+
+#define DRIVER_NAME	"dell-wmi-ddv"
+
+#define DELL_DDV_SUPPORTED_INTERFACE 2
+#define DELL_DDV_GUID	"8A42EA14-4F2A-FD45-6422-0087F7A7E608"
+
+enum dell_ddv_method {
+	DELL_DDV_BATTERY_DESIGN_CAPACITY	= 0x01,
+	DELL_DDV_BATTERY_FULL_CHARGE_CAPACITY	= 0x02,
+	DELL_DDV_BATTERY_MANUFACTURE_NAME	= 0x03,
+	DELL_DDV_BATTERY_MANUFACTURE_DATE	= 0x04,
+	DELL_DDV_BATTERY_SERIAL_NUMBER		= 0x05,
+	DELL_DDV_BATTERY_CHEMISTRY_VALUE	= 0x06,
+	DELL_DDV_BATTERY_TEMPERATURE		= 0x07,
+	DELL_DDV_BATTERY_CURRENT		= 0x08,
+	DELL_DDV_BATTERY_VOLTAGE		= 0x09,
+	DELL_DDV_BATTERY_MANUFACTURER_ACCESS	= 0x0A,
+	DELL_DDV_BATTERY_RELATIVE_CHARGE_STATE	= 0x0B,
+	DELL_DDV_BATTERY_CYCLE_COUNT		= 0x0C,
+	DELL_DDV_BATTERY_EPPID			= 0x0D,
+	DELL_DDV_BATTERY_RAW_ANALYTICS_START	= 0x0E,
+	DELL_DDV_BATTERY_RAW_ANALYTICS		= 0x0F,
+	DELL_DDV_BATTERY_DESIGN_VOLTAGE		= 0x10,
+
+	DELL_DDV_INTERFACE_VERSION		= 0x12,
+
+	DELL_DDV_FAN_SENSOR_INFORMATION		= 0x20,
+	DELL_DDV_THERMAL_SENSOR_INFORMATION	= 0x22,
+};
+
+struct dell_wmi_ddv_data {
+	struct acpi_battery_hook hook;
+	struct device_attribute temp_attr, eppid_attr;
+	struct wmi_device *wdev;
+};
+
+static int dell_wmi_ddv_query_type(struct wmi_device *wdev, enum dell_ddv_method method, u32 arg,
+				   union acpi_object **result, acpi_object_type type)
+{
+	struct acpi_buffer out = { ACPI_ALLOCATE_BUFFER, NULL };
+	const struct acpi_buffer in = {
+		.length = sizeof(arg),
+		.pointer = &arg,
+	};
+	union acpi_object *obj;
+	acpi_status ret;
+
+	ret = wmidev_evaluate_method(wdev, 0x0, method, &in, &out);
+	if (ACPI_FAILURE(ret))
+		return -EIO;
+
+	obj = out.pointer;
+	if (!obj)
+		return -ENODATA;
+
+	if (obj->type != type) {
+		kfree(obj);
+		return -EIO;
+	}
+
+	*result = obj;
+
+	return 0;
+}
+
+static int dell_wmi_ddv_query_integer(struct wmi_device *wdev, enum dell_ddv_method method,
+				      u32 arg, u32 *res)
+{
+	union acpi_object *obj;
+	int ret;
+
+	ret = dell_wmi_ddv_query_type(wdev, method, arg, &obj, ACPI_TYPE_INTEGER);
+	if (ret < 0)
+		return ret;
+
+	if (obj->integer.value <= U32_MAX)
+		*res = (u32)obj->integer.value;
+	else
+		ret = -ERANGE;
+
+	kfree(obj);
+
+	return ret;
+}
+
+static int dell_wmi_ddv_query_buffer(struct wmi_device *wdev, enum dell_ddv_method method,
+				     u32 arg, union acpi_object **result)
+{
+	union acpi_object *obj;
+	u64 buffer_size;
+	int ret;
+
+	ret = dell_wmi_ddv_query_type(wdev, method, arg, &obj, ACPI_TYPE_PACKAGE);
+	if (ret < 0)
+		return ret;
+
+	if (obj->package.count != 2)
+		goto err_free;
+
+	if (obj->package.elements[0].type != ACPI_TYPE_INTEGER)
+		goto err_free;
+
+	buffer_size = obj->package.elements[0].integer.value;
+
+	if (obj->package.elements[1].type != ACPI_TYPE_BUFFER)
+		goto err_free;
+
+	if (buffer_size != obj->package.elements[1].buffer.length) {
+		dev_warn(&wdev->dev,
+			 FW_WARN "ACPI buffer size (%llu) does not match WMI buffer size (%d)\n",
+			 buffer_size, obj->package.elements[1].buffer.length);
+
+		goto err_free;
+	}
+
+	*result = obj;
+
+	return 0;
+
+err_free:
+	kfree(obj);
+
+	return -EIO;
+}
+
+static int dell_wmi_ddv_query_string(struct wmi_device *wdev, enum dell_ddv_method method,
+				     u32 arg, union acpi_object **result)
+{
+	return dell_wmi_ddv_query_type(wdev, method, arg, result, ACPI_TYPE_STRING);
+}
+
+static int dell_wmi_ddv_battery_index(struct acpi_device *acpi_dev, u32 *index)
+{
+	const char *uid_str = acpi_device_uid(acpi_dev);
+
+	if (!uid_str)
+		return -ENODEV;
+
+	return kstrtou32(uid_str, 10, index);
+}
+
+static ssize_t temp_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct dell_wmi_ddv_data *data = container_of(attr, struct dell_wmi_ddv_data, temp_attr);
+	u32 index, value;
+	int ret;
+
+	ret = dell_wmi_ddv_battery_index(to_acpi_device(dev->parent), &index);
+	if (ret < 0)
+		return ret;
+
+	ret = dell_wmi_ddv_query_integer(data->wdev, DELL_DDV_BATTERY_TEMPERATURE, index, &value);
+	if (ret < 0)
+		return ret;
+
+	return sysfs_emit(buf, "%d\n", DIV_ROUND_CLOSEST(value, 10));
+}
+
+static ssize_t eppid_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct dell_wmi_ddv_data *data = container_of(attr, struct dell_wmi_ddv_data, eppid_attr);
+	union acpi_object *obj;
+	u32 index;
+	int ret;
+
+	ret = dell_wmi_ddv_battery_index(to_acpi_device(dev->parent), &index);
+	if (ret < 0)
+		return ret;
+
+	ret = dell_wmi_ddv_query_string(data->wdev, DELL_DDV_BATTERY_EPPID, index, &obj);
+	if (ret < 0)
+		return ret;
+
+	ret = sysfs_emit(buf, "%s\n", obj->string.pointer);
+
+	kfree(obj);
+
+	return ret;
+}
+
+static int dell_wmi_ddv_add_battery(struct power_supply *battery, struct acpi_battery_hook *hook)
+{
+	struct dell_wmi_ddv_data *data = container_of(hook, struct dell_wmi_ddv_data, hook);
+	u32 index;
+	int ret;
+
+	/* Return 0 instead of error to avoid being unloaded */
+	ret = dell_wmi_ddv_battery_index(to_acpi_device(battery->dev.parent), &index);
+	if (ret < 0)
+		return 0;
+
+	ret = device_create_file(&battery->dev, &data->temp_attr);
+	if (ret < 0)
+		return ret;
+
+	ret = device_create_file(&battery->dev, &data->eppid_attr);
+	if (ret < 0) {
+		device_remove_file(&battery->dev, &data->temp_attr);
+
+		return ret;
+	}
+
+	return 0;
+}
+
+static int dell_wmi_ddv_remove_battery(struct power_supply *battery, struct acpi_battery_hook *hook)
+{
+	struct dell_wmi_ddv_data *data = container_of(hook, struct dell_wmi_ddv_data, hook);
+
+	device_remove_file(&battery->dev, &data->temp_attr);
+	device_remove_file(&battery->dev, &data->eppid_attr);
+
+	return 0;
+}
+
+static void dell_wmi_ddv_battery_remove(void *data)
+{
+	struct acpi_battery_hook *hook = data;
+
+	battery_hook_unregister(hook);
+}
+
+static int dell_wmi_ddv_battery_add(struct dell_wmi_ddv_data *data)
+{
+	data->hook.name = "Dell DDV Battery Extension";
+	data->hook.add_battery = dell_wmi_ddv_add_battery;
+	data->hook.remove_battery = dell_wmi_ddv_remove_battery;
+
+	sysfs_attr_init(&data->temp_attr.attr);
+	data->temp_attr.attr.name = "temp";
+	data->temp_attr.attr.mode = 0444;
+	data->temp_attr.show = temp_show;
+
+	sysfs_attr_init(&data->eppid_attr.attr);
+	data->eppid_attr.attr.name = "eppid";
+	data->eppid_attr.attr.mode = 0444;
+	data->eppid_attr.show = eppid_show;
+
+	battery_hook_register(&data->hook);
+
+	return devm_add_action_or_reset(&data->wdev->dev, dell_wmi_ddv_battery_remove, &data->hook);
+}
+
+static int dell_wmi_ddv_buffer_read(struct seq_file *seq, enum dell_ddv_method method)
+{
+	struct device *dev = seq->private;
+	struct dell_wmi_ddv_data *data = dev_get_drvdata(dev);
+	union acpi_object *obj;
+	union acpi_object buf;
+	int ret;
+
+	ret = dell_wmi_ddv_query_buffer(data->wdev, method, 0, &obj);
+	if (ret < 0)
+		return ret;
+
+	buf = obj->package.elements[1];
+	ret = seq_write(seq, buf.buffer.pointer, buf.buffer.length);
+	kfree(obj);
+
+	return ret;
+}
+
+static int dell_wmi_ddv_fan_read(struct seq_file *seq, void *offset)
+{
+	return dell_wmi_ddv_buffer_read(seq, DELL_DDV_FAN_SENSOR_INFORMATION);
+}
+
+static int dell_wmi_ddv_temp_read(struct seq_file *seq, void *offset)
+{
+	return dell_wmi_ddv_buffer_read(seq, DELL_DDV_THERMAL_SENSOR_INFORMATION);
+}
+
+static void dell_wmi_ddv_debugfs_remove(void *data)
+{
+	struct dentry *entry = data;
+
+	debugfs_remove(entry);
+}
+
+static void dell_wmi_ddv_debugfs_init(struct wmi_device *wdev)
+{
+	struct dentry *entry;
+	char name[64];
+
+	scnprintf(name, ARRAY_SIZE(name), "%s-%s", DRIVER_NAME, dev_name(&wdev->dev));
+	entry = debugfs_create_dir(name, NULL);
+
+	debugfs_create_devm_seqfile(&wdev->dev, "fan_sensor_information", entry,
+				    dell_wmi_ddv_fan_read);
+	debugfs_create_devm_seqfile(&wdev->dev, "thermal_sensor_information", entry,
+				    dell_wmi_ddv_temp_read);
+
+	devm_add_action_or_reset(&wdev->dev, dell_wmi_ddv_debugfs_remove, entry);
+}
+
+static int dell_wmi_ddv_probe(struct wmi_device *wdev, const void *context)
+{
+	struct dell_wmi_ddv_data *data;
+	u32 version;
+	int ret;
+
+	ret = dell_wmi_ddv_query_integer(wdev, DELL_DDV_INTERFACE_VERSION, 0, &version);
+	if (ret < 0)
+		return ret;
+
+	dev_dbg(&wdev->dev, "WMI interface version: %d\n", version);
+	if (version != DELL_DDV_SUPPORTED_INTERFACE)
+		return -ENODEV;
+
+	data = devm_kzalloc(&wdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	dev_set_drvdata(&wdev->dev, data);
+	data->wdev = wdev;
+
+	dell_wmi_ddv_debugfs_init(wdev);
+
+	return dell_wmi_ddv_battery_add(data);
+}
+
+static const struct wmi_device_id dell_wmi_ddv_id_table[] = {
+	{ DELL_DDV_GUID, NULL },
+	{ }
+};
+MODULE_DEVICE_TABLE(wmi, dell_wmi_ddv_id_table);
+
+static struct wmi_driver dell_wmi_ddv_driver = {
+	.driver = {
+		.name = DRIVER_NAME,
+	},
+	.id_table = dell_wmi_ddv_id_table,
+	.probe = dell_wmi_ddv_probe,
+};
+module_wmi_driver(dell_wmi_ddv_driver);
+
+MODULE_AUTHOR("Armin Wolf <W_Armin@gmx.de>");
+MODULE_DESCRIPTION("Dell WMI sensor driver");
+MODULE_LICENSE("GPL");
diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c
index aff23309b5d3..f307d8c5c6c3 100644
--- a/drivers/platform/x86/wmi.c
+++ b/drivers/platform/x86/wmi.c
@@ -108,6 +108,7 @@  MODULE_DEVICE_TABLE(acpi, wmi_device_ids);
 /* allow duplicate GUIDs as these device drivers use struct wmi_driver */
 static const char * const allow_duplicates[] = {
 	"05901221-D566-11D1-B2F0-00A0C9062910",	/* wmi-bmof */
+	"8A42EA14-4F2A-FD45-6422-0087F7A7E608",	/* dell-wmi-ddv */
 	NULL
 };