Message-ID: <de122cb5-e245-43e9-8bd7-2fcff1426203@gmx.de>
Date: Thu, 27 Mar 2025 02:29:18 +0100
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 v4 4/6 RESEND] platform/x86: Add Lenovo Capability Data 01
 WMI Driver

Am 17.03.25 um 15:43 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.
>
> Signed-off-by: Derek J. Clark <derekjohn.clark@...il.com>
> ---
> 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                                 |   2 +
>   drivers/platform/x86/Kconfig                |   4 +
>   drivers/platform/x86/Makefile               |   1 +
>   drivers/platform/x86/lenovo-wmi-capdata01.c | 136 ++++++++++++++++++++
>   drivers/platform/x86/lenovo-wmi-capdata01.h |  29 +++++
>   5 files changed, 172 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 6dde75922aaf..56ead241a053 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -13164,6 +13164,8 @@ 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.c
> +F:	drivers/platform/x86/lenovo-wmi-capdata01.h
>   F:	drivers/platform/x86/lenovo-wmi-events.c
>   F:	drivers/platform/x86/lenovo-wmi-events.h
>   F:	drivers/platform/x86/lenovo-wmi-helpers.c
> 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..b6876611ffd9
> --- /dev/null
> +++ b/drivers/platform/x86/lenovo-wmi-capdata01.c
> @@ -0,0 +1,136 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * LENOVO_CAPABILITY_DATA_01 WMI data block driver. This interface provides
> + * information on tunable attributes used by the "Other Mode" WMI interface,
> + * including if it is supported by the hardware, the default_value, max_value,
> + * min_value, and step increment.
> + *
> + * Copyright(C) 2025 Derek J. Clark <derekjohn.clark@...il.com>
> + */
> +
> +#include <linux/cleanup.h>
> +#include <linux/component.h>
> +#include <linux/container_of.h>
> +#include <linux/device.h>
> +#include <linux/gfp_types.h>
> +#include <linux/types.h>
> +#include <linux/wmi.h>
> +#include "lenovo-wmi-capdata01.h"

Hi,

please also include linux/acpi.h, linux/export.h and linux/module.h.

> +
> +/* Interface GUIDs */
> +#define LENOVO_CAPABILITY_DATA_01_GUID "7A8F5407-CB67-4D6E-B547-39B3BE018154"
> +
> +struct lwmi_cd01_priv {
> +	struct wmi_device *wdev;
> +};
> +
> +/*

/* -> /**

> + * lenovo_cd01_component_bind() - On master bind, caches all capability data on
> + * the master device.
> + * @cd01_dev: Pointer to the capability data 01 parent device.
> + * @om_dev: Pointer to the other mode parent device.
> + * @data: capdata01_list object pointer to return the capability data with.
> + *
> + * Returns: 0, or an error.
> + */
> +static int lenovo_cd01_component_bind(struct device *cd01_dev,
> +				      struct device *om_dev, void *data)
> +{
> +	struct lwmi_cd01_priv *priv = dev_get_drvdata(cd01_dev);
> +	int count, idx;
> +
> +	if (!priv)
> +		return -ENODEV;

This check is unnecessary, please drop.

> +
> +	count = wmidev_instance_count(priv->wdev);
> +
> +	if (count == 0)
> +		return -EINVAL;

The WMI driver core already ensures that WMI devices with 0 instances are
rejected. Please drop this check.

> +
> +	((struct cd01_list *)data)->count = count;
> +	((struct cd01_list *)data)->data = devm_kmalloc_array(om_dev, count,
> +							      sizeof(struct capdata01 *),
> +							      GFP_KERNEL);

Two things:

  - using a local variable with a type of struct cd01_list * results in cleaner source code here

  - using devres is not possible inside the component callbacks, since the lifetime of the component
    device is not necessarily tied to the lifetime of the underlying device.

I suggest you move the whole WMI data querying into lwmi_cd01_probe(), because then you can keep using
devres.

> +	if (!data)
> +		return -ENOMEM;
> +
> +	for (idx = 0; idx < count; idx++) {
> +		union acpi_object *ret_obj __free(kfree) = NULL;
> +
> +		ret_obj = wmidev_block_query(priv->wdev, idx);
> +		if (!ret_obj) {
> +			((struct cd01_list *)data)->data[idx] = NULL;
> +			continue;
> +		}
> +		if (ret_obj->type != ACPI_TYPE_BUFFER) {
> +			((struct cd01_list *)data)->data[idx] = NULL;
> +			continue;
> +		}
> +
> +		if (ret_obj->buffer.length != sizeof(struct capdata01)) {
> +			((struct cd01_list *)data)->data[idx] = NULL;
> +			continue;
> +		}
> +
> +		((struct cd01_list *)data)->data[idx] =
> +			devm_kmemdup(om_dev, ret_obj->buffer.pointer,
> +				     ret_obj->buffer.length, GFP_KERNEL);
> +	}
> +	return 0;
> +}
> +
> +static const struct component_ops lenovo_cd01_component_ops = {
> +	.bind = lenovo_cd01_component_bind,
> +};
> +
> +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 = component_add(&wdev->dev, &lenovo_cd01_component_ops);
> +
> +	return ret;

Please just omit the local variable here and return the result of component_add() directly here.

> +}
> +
> +static void lwmi_cd01_remove(struct wmi_device *wdev)
> +{
> +	component_del(&wdev->dev, &lenovo_cd01_component_ops);
> +}
> +
> +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,
> +};
> +
> +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..c7067a8d0398
> --- /dev/null
> +++ b/drivers/platform/x86/lenovo-wmi-capdata01.h
> @@ -0,0 +1,29 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later

SPDX license identifiers need to be a separate comment.

> + *
> + * Copyright(C) 2025 Derek J. Clark <derekjohn.clark@...il.com>
> + *
> + */
> +
> +#ifndef _LENOVO_WMI_CAPDATA01_H_
> +#define _LENOVO_WMI_CAPDATA01_H_
> +
> +#include <linux/device.h>
> +#include <linux/types.h>
> +
> +struct capdata01 {
> +	u32 id;
> +	u32 supported;
> +	u32 default_value;
> +	u32 step;
> +	u32 min_value;
> +	u32 max_value;
> +};
> +
> +struct cd01_list {
> +	struct capdata01 **data;
> +	int count;
> +};

In order to save memory you could try something like this:

struct cd01_list {
	size_t count;
	struct capdata01 data[];
};

This way you

1. Avoid the memory fragmentation resulting from multiple memory allocations.

2. Omit two pointers when accessing the data.

You can use struct_size() from linux/overflow.h to calculate the size of such
an array with a trailing flexible array.

Thanks,
Armin Wolf

> +
> +int lwmi_cd01_match(struct device *dev, void *data);
> +
> +#endif /* !_LENOVO_WMI_CAPDATA01_H_ */

Powered by blists - more mailing lists