Message-ID: <99496c39-d25f-48b0-8746-261584e3fc67@gmx.de>
Date: Fri, 2 May 2025 23:10:39 +0200
From: Armin Wolf <W_Armin@....de>
To: "Derek J. Clark" <derekjohn.clark@...il.com>,
 Hans de Goede <hdegoede@...hat.com>,
 Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc: Jonathan Corbet <corbet@....net>, Mario Limonciello <superm1@...nel.org>,
 Luke Jones <luke@...nes.dev>, Xino Ni <nijs1@...ovo.com>,
 Zhixin Zhang <zhangzx36@...ovo.com>, Mia Shao <shaohz1@...ovo.com>,
 Mark Pearson <mpearson-lenovo@...ebb.ca>,
 "Pierre-Loup A . Griffais" <pgriffais@...vesoftware.com>,
 "Cody T . -H . Chiu" <codyit@...il.com>, John Martens <johnfanv2@...il.com>,
 platform-driver-x86@...r.kernel.org, linux-doc@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 4/6] platform/x86: Add Lenovo WMI Capability Data 01
 Driver

Am 02.05.25 um 17:51 schrieb Derek J. Clark:

>
> On May 1, 2025 7:18:40 PM PDT, Armin Wolf <W_Armin@....de> wrote:
>> Am 28.04.25 um 03:18 schrieb Derek J. Clark:
>>
>>> Adds lenovo-wmi-capdata01 driver which provides the
>>> LENOVO_CAPABILITY_DATA_01 WMI data block that comes on "Other Mode"
>>> enabled hardware. Provides an interface for querying if a given
>>> attribute is supported by the hardware, as well as its default_value,
>>> max_value, min_value, and step increment.
>>>
>>> Reviewed-by: Armin Wolf <W_Armin@....de>
>>> Signed-off-by: Derek J. Clark <derekjohn.clark@...il.com>
>>> ---
>>> v6:
>>>    - Recache capabiltiy data on ACPI AC events to ensure accutare
>>>      max_value.
>>>    - Fix typos and rewordings from v5 review.
>>> v5:
>>>    - Return to cache at device initialization. On component bind, pass a
>>>      pointer to lenovo-wmi-other.
>>>    - Fixes from v4 review.
>>> v4:
>>>    - Make driver data a private struct, remove references from Other Mode
>>>      driver.
>>>    - Don't cache data at device initialization. Instead, on component bind,
>>>      cache the data on a member variable of the Other Mode driver data
>>>      passed as a void pointer.
>>>    - Add header file for capdata01 structs.
>>>    - Add new struct to pass capdata01 array data and array length to Other
>>>      Mode.
>>> v3:
>>> - Add as component to lenovo-wmi-other driver.
>>> v2:
>>> - Use devm_kmalloc to ensure driver can be instanced, remove global
>>>     reference.
>>> - Ensure reverse Christmas tree for all variable declarations.
>>> - Remove extra whitespace.
>>> - Use guard(mutex) in all mutex instances, global mutex.
>>> - Use pr_fmt instead of adding the driver name to each pr_err.
>>> - Remove noisy pr_info usage.
>>> - Rename capdata_wmi to lenovo_wmi_cd01_priv and cd01_wmi to priv.
>>> - Use list to get the lenovo_wmi_cd01_priv instance in
>>>     lenovo_wmi_capdata01_get as none of the data provided by the macros
>>>     that will use it can pass a member of the struct for use in
>>>     container_of.
>>>    MAINTAINERS                                 |   1 +
>>>    drivers/platform/x86/Kconfig                |   4 +
>>>    drivers/platform/x86/Makefile               |   1 +
>>>    drivers/platform/x86/lenovo-wmi-capdata01.c | 272 ++++++++++++++++++++
>>>    drivers/platform/x86/lenovo-wmi-capdata01.h |  29 +++
>>>    5 files changed, 307 insertions(+)
>>>    create mode 100644 drivers/platform/x86/lenovo-wmi-capdata01.c
>>>    create mode 100644 drivers/platform/x86/lenovo-wmi-capdata01.h
>>>
>>> diff --git a/MAINTAINERS b/MAINTAINERS
>>> index 2b4b06e81192..1b22e41cc730 100644
>>> --- a/MAINTAINERS
>>> +++ b/MAINTAINERS
>>> @@ -13164,6 +13164,7 @@ L:	platform-driver-x86@...r.kernel.org
>>>    S:	Maintained
>>>    F:	Documentation/wmi/devices/lenovo-wmi-gamezone.rst
>>>    F:	Documentation/wmi/devices/lenovo-wmi-other.rst
>>> +F:	drivers/platform/x86/lenovo-wmi-capdata01.*
>>>    F:	drivers/platform/x86/lenovo-wmi-events.*
>>>    F:	drivers/platform/x86/lenovo-wmi-helpers.*
>>>    diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
>>> index 13b8f4ac5dc5..64663667f0cb 100644
>>> --- a/drivers/platform/x86/Kconfig
>>> +++ b/drivers/platform/x86/Kconfig
>>> @@ -467,6 +467,10 @@ config LENOVO_WMI_HELPERS
>>>    	tristate
>>>    	depends on ACPI_WMI
>>>    +config LENOVO_WMI_DATA01
>>> +	tristate
>>> +	depends on ACPI_WMI
>>> +
>>>    config IDEAPAD_LAPTOP
>>>    	tristate "Lenovo IdeaPad Laptop Extras"
>>>    	depends on ACPI
>>> diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
>>> index fc039839286a..7a35c77221b7 100644
>>> --- a/drivers/platform/x86/Makefile
>>> +++ b/drivers/platform/x86/Makefile
>>> @@ -69,6 +69,7 @@ obj-$(CONFIG_THINKPAD_LMI)	+= think-lmi.o
>>>    obj-$(CONFIG_YOGABOOK)		+= lenovo-yogabook.o
>>>    obj-$(CONFIG_YT2_1380)		+= lenovo-yoga-tab2-pro-1380-fastcharger.o
>>>    obj-$(CONFIG_LENOVO_WMI_CAMERA)	+= lenovo-wmi-camera.o
>>> +obj-$(CONFIG_LENOVO_WMI_DATA01)	+= lenovo-wmi-capdata01.o
>>>    obj-$(CONFIG_LENOVO_WMI_EVENTS)	+= lenovo-wmi-events.o
>>>    obj-$(CONFIG_LENOVO_WMI_HELPERS)	+= lenovo-wmi-helpers.o
>>>    diff --git a/drivers/platform/x86/lenovo-wmi-capdata01.c b/drivers/platform/x86/lenovo-wmi-capdata01.c
>>> new file mode 100644
>>> index 000000000000..841d4a37249b
>>> --- /dev/null
>>> +++ b/drivers/platform/x86/lenovo-wmi-capdata01.c
>>> @@ -0,0 +1,272 @@
>>> +// SPDX-License-Identifier: GPL-2.0-or-later
>>> +/*
>>> + * Lenovo Capability Data 01 WMI Data Block driver.
>>> + *
>>> + * Lenovo Capability Data 01 provides information on tunable attributes used by
>>> + * the "Other Mode" WMI interface. The data includes if the attribute is
>>> + * supported by the hardware, the default_value, max_value, min_value, and step
>>> + * increment. Each attibute has multiple pages, one for each of the thermal
>>> + * modes managed by the Gamezone interface.
>>> + *
>>> + * Copyright(C) 2025 Derek J. Clark <derekjohn.clark@...il.com>
>>> + */
>>> +
>>> +#include <linux/acpi.h>
>>> +#include <linux/cleanup.h>
>>> +#include <linux/component.h>
>>> +#include <linux/container_of.h>
>>> +#include <linux/device.h>
>>> +#include <linux/export.h>
>>> +#include <linux/gfp_types.h>
>>> +#include <linux/module.h>
>>> +#include <linux/notifier.h>
>>> +#include <linux/overflow.h>
>>> +#include <linux/types.h>
>>> +#include <linux/wmi.h>
>>> +
>>> +#include "lenovo-wmi-capdata01.h"
>>> +
>>> +#define LENOVO_CAPABILITY_DATA_01_GUID "7A8F5407-CB67-4D6E-B547-39B3BE018154"
>>> +
>>> +#define ACPI_AC_NOTIFY_STATUS 0x80
>>> +
>>> +static DEFINE_MUTEX(list_mutex);
>> Hi,
>>
>> why not moving this mutex inside struct cd01_list?
>>
> I can do that. Is that preferable over adding it to priv?

You can also add it to priv, but keep in mind that lwmi_cd01_get_data() needs to access it.

>>> +
>>> +struct lwmi_cd01_priv {
>>> +	struct notifier_block acpi_nb; /* ACPI events */
>>> +	struct wmi_device *wdev;
>>> +	struct cd01_list *list;
>>> +};
>>> +
>>> +/**
>>> + * lwmi_cd01_component_bind() - Bind component to master device.
>>> + * @cd01_dev: Pointer to the lenovo-wmi-capdata01 driver parent device.
>>> + * @om_dev: Pointer to the lenovo-wmi-other driver parent device.
>>> + * @data: capdata01_list object pointer used to return the capability data.
>>> + *
>>> + * On lenovo-wmi-other's master bind, provide a pointer to the local capdata01
>>> + * list. This is used to call lwmi_cd01_get_data to look up attribute data
>>> + * from the lenovo-wmi-other driver.
>>> + *
>>> +:* Return: 0 on success, or an error code.
>>> + */
>>> +static int lwmi_cd01_component_bind(struct device *cd01_dev,
>>> +				    struct device *om_dev, void *data)
>>> +{
>>> +	struct lwmi_cd01_priv *priv = dev_get_drvdata(cd01_dev);
>>> +	struct cd01_list **cd01_list = data;
>>> +
>>> +	if (!priv->list)
>>> +		return -ENODEV;
>>> +
>>> +	*cd01_list = priv->list;
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static const struct component_ops lwmi_cd01_component_ops = {
>>> +	.bind = lwmi_cd01_component_bind,
>>> +};
>>> +
>>> +/**
>>> + * lwmi_cd01_get_data - Get the data of the specified attribute
>>> + * @dev: The lenovo-wmi-capdata01 parent device.
>>> + * @tunable_attr: The attribute to be populated.
>>> + *
>>> + * Retrieves the capability data 01 struct pointer for the given
>>> + * attribute for its specified thermal mode.
>>> + *
>>> + * Return: Either a pointer to capability data, or NULL.
>>> + */
>>> +struct capdata01 *lwmi_cd01_get_data(struct cd01_list *list, u32 attribute_id)
>>> +{
>>> +	u8 idx;
>>> +
>>> +	guard(mutex)(&list_mutex);
>>> +	for (idx = 0; idx < list->count; idx++) {
>>> +		if (list->data[idx].id != attribute_id)
>>> +			continue;
>>> +		return &list->data[idx];
>> This might cause issues should lwmi_cd01_cache() be called when the caller of this function
>> currently accesses the returned data.
>>
>> Maybe it would make sense to simply copy the struct capdata01? It is rather small, so the overhead
>> would be negligible.
>>
>> I envision something like this:
>>
>> int lwmi_cd01_get_data(struct cd01_list *list, u32 attribute_id, struct capdata01 *output);
>>
>> In this case the resulting capdata is copied into "output".
>>
> I can make this work. I assume memcpy is preferred. Should I make the source pointer a devm kmalloc before it's sent or use the stack?

I suggest that you let the caller decide that. Inside lwmi_cd01_get_data() you simply use memcpy() with "output" being the destination.
The caller will take care of providing the memory referenced by "output".

Thanks,
Armin Wolf

>>> +	}
>>> +	return NULL;
>>> +}
>>> +EXPORT_SYMBOL_NS_GPL(lwmi_cd01_get_data, "LENOVO_WMI_CD01");
>>> +
>>> +/**
>>> + * lwmi_cd01_setup() - Cache all WMI data block information
>>> + * @priv: lenovo-wmi-capdata01 driver data.
>>> + *
>>> + * Loop through each WMI data block and cache the data.
>>> + *
>>> + * Return: 0 on success, or an error.
>>> + */
>>> +static int lwmi_cd01_cache(struct lwmi_cd01_priv *priv)
>>> +{
>>> +	int idx;
>>> +
>>> +	guard(mutex)(&list_mutex);
>>> +	for (idx = 0; idx < priv->list->count; idx++) {
>>> +		union acpi_object *ret_obj __free(kfree) = NULL;
>>> +
>>> +		ret_obj = wmidev_block_query(priv->wdev, idx);
>>> +		if (!ret_obj)
>>> +			return -ENODEV;
>>> +
>>> +		if (ret_obj->type != ACPI_TYPE_BUFFER ||
>>> +		    ret_obj->buffer.length < sizeof(priv->list->data[idx]))
>>> +			continue;
>>> +
>>> +		memcpy(&priv->list->data[idx], ret_obj->buffer.pointer,
>>> +		       ret_obj->buffer.length);
>>> +	}
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +/**
>>> + * lwmi_cd01_alloc() - Allocate a cd01_list struct in drvdata
>>> + * @priv: lenovo-wmi-capdata01 driver data.
>>> + *
>>> + * Allocate a cd01_list struct large enough to contain data from all WMI data
>>> + * blocks provided by the interface.
>>> + *
>>> + * Return: 0 on success, or an error.
>>> + */
>>> +static int lwmi_cd01_alloc(struct lwmi_cd01_priv *priv)
>>> +{
>>> +	struct cd01_list *list;
>>> +	size_t list_size;
>>> +	int count;
>>> +
>>> +	count = wmidev_instance_count(priv->wdev);
>>> +	list_size = struct_size(list, data, count);
>>> +
>>> +	guard(mutex)(&list_mutex);
>>> +	list = devm_kzalloc(&priv->wdev->dev, list_size, GFP_KERNEL);
>>> +	if (!list)
>>> +		return -ENOMEM;
>>> +
>>> +	list->count = count;
>>> +	priv->list = list;
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +/**
>>> + * lwmi_cd01_setup() - Cache all WMI data block information
>>> + * @priv: lenovo-wmi-capdata01 driver data.
>>> + *
>>> + * Allocate a cd01_list struct large enough to contain data from all WMI data
>>> + * blocks provided by the interface. Then loop through each data block and
>>> + * cache the data.
>>> + *
>>> + * Return: 0 on success, or an error code.
>>> + */
>>> +static int lwmi_cd01_setup(struct lwmi_cd01_priv *priv)
>>> +{
>>> +	int ret;
>>> +
>>> +	ret = lwmi_cd01_alloc(priv);
>>> +	if (ret)
>>> +		return ret;
>>> +
>>> +	return lwmi_cd01_cache(priv);
>>> +}
>>> +
>>> +/**
>>> + * lwmi_cd01_notifier_call() - Call method for lenovo-wmi-capdata01 driver notifier.
>>> + * block call chain.
>>> + * @nb: The notifier_block registered to lenovo-wmi-events driver.
>>> + * @action: Unused.
>>> + * @data: The ACPI event.
>>> + *
>>> + * For LWMI_EVENT_THERMAL_MODE, set current_mode and notify platform_profile
>>> + * of a change.
>>> + *
>>> + * Return: notifier_block status.
>>> + */
>>> +static int lwmi_cd01_notifier_call(struct notifier_block *nb, unsigned long action,
>>> +				   void *data)
>>> +{
>>> +	struct acpi_bus_event *event = (struct acpi_bus_event *)data;
>> Unnecessary cast, please drop.
>>
>>> +	struct lwmi_cd01_priv *priv;
>>> +	int ret;
>>> +
>>> +
>>> +	priv = container_of(nb, struct lwmi_cd01_priv, acpi_nb);
>>> +
>>> +	switch (event->type) {
>>> +	case ACPI_AC_NOTIFY_STATUS:
>> You should also check the the "device_class" of the ACPI event (search for ACPI_AC_CLASS)
>> because "type" is not guaranteed to be unique between different events.
>>
> Good to know, thanks.
>
>
> Ack all below.
>   
> Thanks,
> Derek
>
>>> +		ret = lwmi_cd01_cache(priv);
>>> +		if (ret)
>>> +			return NOTIFY_BAD;
>>> +
>>> +		return NOTIFY_OK;
>>> +	default:
>>> +		return NOTIFY_DONE;
>>> +	}
>>> +}
>>> +
>>> +static int lwmi_cd01_probe(struct wmi_device *wdev, const void *context)
>>> +
>>> +{
>>> +	struct lwmi_cd01_priv *priv;
>>> +	int ret;
>>> +
>>> +	priv = devm_kzalloc(&wdev->dev, sizeof(*priv), GFP_KERNEL);
>>> +	if (!priv)
>>> +		return -ENOMEM;
>>> +
>>> +	priv->wdev = wdev;
>>> +	dev_set_drvdata(&wdev->dev, priv);
>>> +
>>> +	ret = lwmi_cd01_setup(priv);
>>> +	if (ret)
>>> +		return ret;
>>> +
>>> +	priv->acpi_nb.notifier_call = lwmi_cd01_notifier_call;
>>> +	register_acpi_notifier(&priv->acpi_nb);
>>> +
>>> +	return component_add(&wdev->dev, &lwmi_cd01_component_ops);
>> You need to unregister the ACPI notifier when component_add() fails.
>>
>>> +}
>>> +
>>> +static void lwmi_cd01_remove(struct wmi_device *wdev)
>>> +{
>>> +	component_del(&wdev->dev, &lwmi_cd01_component_ops);
>> Same as above. You could use devm_add_action_or_reset() to fix both cases.
>>
>>> +}
>>> +
>>> +static const struct wmi_device_id lwmi_cd01_id_table[] = {
>>> +	{ LENOVO_CAPABILITY_DATA_01_GUID, NULL },
>>> +	{}
>>> +};
>>> +
>>> +static struct wmi_driver lwmi_cd01_driver = {
>>> +	.driver = {
>>> +		.name = "lenovo_wmi_cd01",
>>> +		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
>>> +	},
>>> +	.id_table = lwmi_cd01_id_table,
>>> +	.probe = lwmi_cd01_probe,
>>> +	.remove = lwmi_cd01_remove,
>>> +	.no_singleton = true,
>>> +};
>>> +
>>> +/**
>>> + * lwmi_cd01_match() - Match rule for the master driver.
>>> + * @dev: Pointer to the capability data 01 parent device.
>>> + * @data: Unused void pointer for passing match criteria.
>>> + *
>>> + * Return: int.
>>> + */
>>> +int lwmi_cd01_match(struct device *dev, void *data)
>>> +{
>>> +	return dev->driver == &lwmi_cd01_driver.driver;
>>> +}
>>> +EXPORT_SYMBOL_NS_GPL(lwmi_cd01_match, "LENOVO_WMI_CD01");
>>> +
>>> +module_wmi_driver(lwmi_cd01_driver);
>>> +
>>> +MODULE_DEVICE_TABLE(wmi, lwmi_cd01_id_table);
>>> +MODULE_AUTHOR("Derek J. Clark <derekjohn.clark@...il.com>");
>>> +MODULE_DESCRIPTION("Lenovo Capability Data 01 WMI Driver");
>>> +MODULE_LICENSE("GPL");
>>> diff --git a/drivers/platform/x86/lenovo-wmi-capdata01.h b/drivers/platform/x86/lenovo-wmi-capdata01.h
>>> new file mode 100644
>>> index 000000000000..ed4f3d86464d
>>> --- /dev/null
>>> +++ b/drivers/platform/x86/lenovo-wmi-capdata01.h
>>> @@ -0,0 +1,29 @@
>>> +/* SPDX-License-Identifier: GPL-2.0-or-later */
>>> +
>>> +/* Copyright(C) 2025 Derek J. Clark <derekjohn.clark@...il.com> */
>>> +
>>> +#ifndef _LENOVO_WMI_CAPDATA01_H_
>>> +#define _LENOVO_WMI_CAPDATA01_H_
>>> +
>>> +#include <linux/types.h>
>>> +
>>> +struct device;
>>> +
>>> +struct capdata01 {
>>> +	u32 id;
>>> +	u32 supported;
>>> +	u32 default_value;
>>> +	u32 step;
>>> +	u32 min_value;
>>> +	u32 max_value;
>>> +};
>>> +
>>> +struct cd01_list {
>>> +	u8 count;
>>> +	struct capdata01 data[];
>>> +};
>> Since client driver are not directly accessing this struct anyway please keep its definition private
>> and only provide an incomplete definition in this header:
>>
>> 	struct cd01_list *;
>>
>> Thanks,
>> Armin Wolf
>>
>>> +
>>> +struct capdata01 *lwmi_cd01_get_data(struct cd01_list *list, u32 attribute_id);
>>> +int lwmi_cd01_match(struct device *dev, void *data);
>>> +
>>> +#endif /* !_LENOVO_WMI_CAPDATA01_H_ */
> - Derek
>

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