Re: [PATCH v11 15/15] platform/x86: lenovo-wmi-capdata: Add debugfs file for dumping capdata

["Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>]

On Thu, 7 May 2026, Derek J. Clark wrote:

> From: Rong Zhang <i@rong.moe>
> 
> The Lenovo GameZone/Other interfaces have some delicate divergences
> among different devices. When making a bug report or adding support for
> new devices/interfaces, capdata is the most important information to
> cross-check with.
> 
> Add a debugfs file (lenovo_wmi/<device_name>/capdata), so that users can
> dump capdata and include it in their reports.
> 
> Since `struct capdata01' is just an extension to `struct capdata00',
> also converts the former to include the latter anonymously
> (-fms-extensions, since v6.19). In this manner type casting won't be
> confusing.
> 
> Tested-by: Kurt Borja <kuurtb@gmail.com>
> Signed-off-by: Rong Zhang <i@rong.moe>
> Signed-off-by: Derek J. Clark <derekjohn.clark@gmail.com>
> ---
>  drivers/platform/x86/lenovo/Kconfig       |   1 +
>  drivers/platform/x86/lenovo/wmi-capdata.c | 120 ++++++++++++++++++++++
>  drivers/platform/x86/lenovo/wmi-capdata.h |   4 +-
>  3 files changed, 122 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/platform/x86/lenovo/Kconfig b/drivers/platform/x86/lenovo/Kconfig
> index b9a5d18caa1e..4443f40ef8aa 100644
> --- a/drivers/platform/x86/lenovo/Kconfig
> +++ b/drivers/platform/x86/lenovo/Kconfig
> @@ -236,6 +236,7 @@ config YT2_1380
>  config LENOVO_WMI_CAPDATA
>  	tristate
>  	depends on ACPI_WMI
> +	depends on LENOVO_WMI_HELPERS
>  
>  config LENOVO_WMI_EVENTS
>  	tristate
> diff --git a/drivers/platform/x86/lenovo/wmi-capdata.c b/drivers/platform/x86/lenovo/wmi-capdata.c
> index 169665be4dcf..b5e2c16d638f 100644
> --- a/drivers/platform/x86/lenovo/wmi-capdata.c
> +++ b/drivers/platform/x86/lenovo/wmi-capdata.c
> @@ -31,6 +31,7 @@
>  #include <linux/cleanup.h>
>  #include <linux/component.h>
>  #include <linux/container_of.h>
> +#include <linux/debugfs.h>
>  #include <linux/device.h>
>  #include <linux/dev_printk.h>
>  #include <linux/err.h>
> @@ -42,6 +43,7 @@
>  #include <linux/mutex_types.h>
>  #include <linux/notifier.h>
>  #include <linux/overflow.h>
> +#include <linux/seq_file.h>
>  #include <linux/stddef.h>
>  #include <linux/types.h>
>  #include <linux/wmi.h>
> @@ -88,6 +90,7 @@ struct lwmi_cd_priv {
>  	struct notifier_block acpi_nb; /* ACPI events */
>  	struct wmi_device *wdev;
>  	struct cd_list *list;
> +	struct dentry *debugfs_dir;
>  
>  	/*
>  	 * A capdata device may be a component master of another capdata device.
> @@ -118,6 +121,8 @@ struct cd_list {
>  
>  static struct wmi_driver lwmi_cd_driver;
>  
> +/* ======== Device components ======== */
> +
>  /**
>   * lwmi_cd_match() - Match rule for the master driver.
>   * @dev: Pointer to the capability data parent device.
> @@ -471,6 +476,116 @@ EXPORT_SYMBOL_NS_GPL(lwmi_cd01_get_data, "LENOVO_WMI_CAPDATA");
>  DEF_LWMI_CDXX_GET_DATA(cd_fan, LENOVO_FAN_TEST_DATA, struct capdata_fan);
>  EXPORT_SYMBOL_NS_GPL(lwmi_cd_fan_get_data, "LENOVO_WMI_CAPDATA");
>  
> +/* ======== debugfs ======== */
> +
> +/**
> + * lwmi_cd00_show() - Dump capdata00
> + * @s: Pointer to seq_file where the capdata00 is dumped.
> + * @cd00: Pointer to a capdata00 struct to be dumped.
> + */
> +static void lwmi_cd00_show(struct seq_file *s, struct capdata00 *cd00)
> +{
> +	u8 dev = FIELD_GET(LWMI_ATTR_DEV_ID_MASK, cd00->id);
> +	u8 feat = FIELD_GET(LWMI_ATTR_FEAT_ID_MASK, cd00->id);
> +	u8 mode = FIELD_GET(LWMI_ATTR_MODE_ID_MASK, cd00->id);
> +	u8 type = FIELD_GET(LWMI_ATTR_TYPE_ID_MASK, cd00->id);
> +	bool extra = cd00->supported & ~(LWMI_SUPP_GET | LWMI_SUPP_SET | LWMI_SUPP_VALID);
> +	bool get = cd00->supported & LWMI_SUPP_GET;
> +	bool set = cd00->supported & LWMI_SUPP_SET;
> +	bool valid = cd00->supported & LWMI_SUPP_VALID;
> +
> +	seq_printf(s, "  id:             0x%08x [dev: %2u, feat: %2u, mode: %2u, type: %2u]\n",
> +		   cd00->id, dev, feat, mode, type);
> +
> +	seq_printf(s, "  supported:      0x%08x [%c%c%c%c]\n", cd00->supported,
> +		   extra ? '+' : ' ',
> +		   get   ? 'R' : ' ',
> +		   set   ? 'W' : ' ',
> +		   valid ? 'V' : ' ');
> +
> +	seq_printf(s, "  default_value:  %u\n", cd00->default_value);
> +}
> +
> +/**
> + * lwmi_cd01_show() - Dump capdata01
> + * @s: Pointer to seq_file where the capdata01 is dumped.
> + * @cd01: Pointer to a capdata01 struct to be dumped.
> + */
> +static void lwmi_cd01_show(struct seq_file *s, struct capdata01 *cd01)
> +{
> +	/* capdata01 is an extension to capdata00. */
> +	lwmi_cd00_show(s, (struct capdata00 *)cd01);

Hpmf, so anonymous struct leads to this now.

I wonder if we could wrap it with an union to have both named access to it 
(to get the pointer without casting) while retaining anonymous access to 
its members:

struct capdata01 {
	union {
		struct capdata00;
		struct capdata00 cd00;
	};
	...

...If it's not possible, then I'll have to accept the cast I guess.

> +	seq_printf(s, "  step:           %u\n", cd01->step);
> +	seq_printf(s, "  min_value:      %u\n", cd01->min_value);
> +	seq_printf(s, "  max_value:      %u\n", cd01->max_value);
> +}
> +
> +/**
> + * lwmi_cd_fan_show() - Dump capdata_fan
> + * @s: Pointer to seq_file where the capdata_fan is dumped.
> + * @cd_fan: Pointer to a capdata_fan struct to be dumped.
> + */
> +static void lwmi_cd_fan_show(struct seq_file *s, struct capdata_fan *cd_fan)
> +{
> +	seq_printf(s, "  id:             %u\n", cd_fan->id);
> +	seq_printf(s, "  min_rpm:        %u\n", cd_fan->min_rpm);
> +	seq_printf(s, "  max_rpm:        %u\n", cd_fan->max_rpm);
> +}
> +
> +/**
> + * lwmi_cd_debugfs_show() - Dump capability data to debugfs
> + * @s: Pointer to seq_file where the capability data is dumped.
> + * @data: unused.
> + *
> + * Return: 0
> + */
> +static int lwmi_cd_debugfs_show(struct seq_file *s, void *data)
> +{
> +	struct lwmi_cd_priv *priv = s->private;
> +	u8 idx;
> +
> +	guard(mutex)(&priv->list->list_mutex);
> +
> +	/* lwmi_cd_alloc() ensured priv->list->type must be a valid type. */
> +	for (idx = 0; idx < priv->list->count; idx++) {
> +		seq_printf(s, "%s[%u]:\n", lwmi_cd_table[priv->list->type].name, idx);
> +
> +		if (priv->list->type == LENOVO_CAPABILITY_DATA_00)
> +			lwmi_cd00_show(s, &priv->list->cd00[idx]);
> +		else if (priv->list->type == LENOVO_CAPABILITY_DATA_01)
> +			lwmi_cd01_show(s, &priv->list->cd01[idx]);
> +		else if (priv->list->type == LENOVO_FAN_TEST_DATA)
> +			lwmi_cd_fan_show(s, &priv->list->cd_fan[idx]);
> +	}
> +
> +	return 0;
> +}
> +DEFINE_SHOW_ATTRIBUTE(lwmi_cd_debugfs);
> +
> +/**
> + * lwmi_cd_debugfs_add() - Create debugfs directory and files for a device
> + * @priv: lenovo-wmi-capdata driver data.
> + */
> +static void lwmi_cd_debugfs_add(struct lwmi_cd_priv *priv)
> +{
> +	priv->debugfs_dir = lwmi_debugfs_create_dir(priv->wdev);
> +
> +	debugfs_create_file("capdata", 0444, priv->debugfs_dir, priv, &lwmi_cd_debugfs_fops);
> +}
> +
> +/**
> + * lwmi_cd_debugfs_remove() - Remove debugfs directory for a device
> + * @priv: lenovo-wmi-capdata driver data.
> + */
> +static void lwmi_cd_debugfs_remove(struct lwmi_cd_priv *priv)
> +{
> +	debugfs_remove_recursive(priv->debugfs_dir);
> +	priv->debugfs_dir = NULL;
> +}
> +
> +/* ======== WMI interface ======== */
> +
>  /**
>   * lwmi_cd_cache() - Cache all WMI data block information
>   * @priv: lenovo-wmi-capdata driver data.
> @@ -773,6 +888,8 @@ static int lwmi_cd_probe(struct wmi_device *wdev, const void *context)
>  		dev_err(&wdev->dev, "failed to register %s: %d\n",
>  			info->name, ret);
>  	} else {
> +		lwmi_cd_debugfs_add(priv);
> +
>  		dev_dbg(&wdev->dev, "registered %s with %u items\n",
>  			info->name, priv->list->count);
>  	}
> @@ -783,6 +900,8 @@ static void lwmi_cd_remove(struct wmi_device *wdev)
>  {
>  	struct lwmi_cd_priv *priv = dev_get_drvdata(&wdev->dev);
>  
> +	lwmi_cd_debugfs_remove(priv);
> +
>  	switch (priv->list->type) {
>  	case LENOVO_CAPABILITY_DATA_00:
>  		lwmi_cd_sub_master_del(priv);
> @@ -822,6 +941,7 @@ static struct wmi_driver lwmi_cd_driver = {
>  
>  module_wmi_driver(lwmi_cd_driver);
>  
> +MODULE_IMPORT_NS("LENOVO_WMI_HELPERS");
>  MODULE_DEVICE_TABLE(wmi, lwmi_cd_id_table);
>  MODULE_AUTHOR("Derek J. Clark <derekjohn.clark@gmail.com>");
>  MODULE_AUTHOR("Rong Zhang <i@rong.moe>");
> diff --git a/drivers/platform/x86/lenovo/wmi-capdata.h b/drivers/platform/x86/lenovo/wmi-capdata.h
> index e0a30f2c0c87..0df3ae534ed5 100644
> --- a/drivers/platform/x86/lenovo/wmi-capdata.h
> +++ b/drivers/platform/x86/lenovo/wmi-capdata.h
> @@ -38,9 +38,7 @@ struct capdata00 {
>  };
>  
>  struct capdata01 {
> -	u32 id;
> -	u32 supported;
> -	u32 default_value;
> +	struct capdata00;
>  	u32 step;
>  	u32 min_value;
>  	u32 max_value;
> 

-- 
 i.