Message-ID: <64d3f499-baa3-5039-dc87-c3581623ce8c@linux.intel.com>
Date: Mon, 12 Jan 2026 19:25:15 +0200 (EET)
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Rong Zhang <i@...g.moe>
cc: Mark Pearson <mpearson-lenovo@...ebb.ca>, 
    "Derek J. Clark" <derekjohn.clark@...il.com>, Armin Wolf <W_Armin@....de>, 
    Hans de Goede <hansg@...nel.org>, 
    Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>, 
    Guenter Roeck <linux@...ck-us.net>, platform-driver-x86@...r.kernel.org, 
    linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org
Subject: Re: [PATCH v7 5/7] platform/x86: lenovo-wmi-capdata: Add support
 for Fan Test Data

On Wed, 26 Nov 2025, Rong Zhang wrote:

> Add support for LENOVO_FAN_TEST_DATA WMI data block. Provides an
> interface for querying the min/max fan speed RPM (reference data) of a
> given fan ID.
> 
> This interface is optional. Hence, it does not bind to lenovo-wmi-other
> and is not registered as a component for the moment. Appropriate binding
> will be implemented in the subsequent patch.
> 
> Signed-off-by: Rong Zhang <i@...g.moe>
> Reviewed-by: Derek J. Clark <derekjohn.clark@...il.com>
> Tested-by: Derek J. Clark <derekjohn.clark@...il.com>
> ---
> Changes in v7:
> - Rearrange lwmi_cd_fan_list_alloc_cache() to drop gotos (thanks Ilpo
>   Järvinen)
> - Move the declarations of __free()-managed variablesto where thet are
>   assigned (ditto)
> - Prevent back-and-forth changes (ditto)
> - Improve the readablity of struct definition (ditto)
> - Emit unaligned access to the WMI block
> - Properly calculate array index when we truncate the data
> 
> Changes in v4:
> - Rebase on top of changes made to [PATCH v4 3/7]
> - Do not register it as a component until [PATCH v4 6/7]
> 
> Changes in v2:
> - Reword documentation
> ---
>  .../wmi/devices/lenovo-wmi-other.rst          | 17 ++++
>  drivers/platform/x86/lenovo/wmi-capdata.c     | 96 +++++++++++++++++++
>  drivers/platform/x86/lenovo/wmi-capdata.h     |  7 ++
>  3 files changed, 120 insertions(+)
> 
> diff --git a/Documentation/wmi/devices/lenovo-wmi-other.rst b/Documentation/wmi/devices/lenovo-wmi-other.rst
> index fcad595d49af..821282e07d93 100644
> --- a/Documentation/wmi/devices/lenovo-wmi-other.rst
> +++ b/Documentation/wmi/devices/lenovo-wmi-other.rst
> @@ -62,6 +62,13 @@ The following firmware-attributes are implemented:
>   - ppt_pl2_sppt: Platform Profile Tracking Slow Package Power Tracking
>   - ppt_pl3_fppt: Platform Profile Tracking Fast Package Power Tracking
>  
> +LENOVO_FAN_TEST_DATA
> +-------------------------
> +
> +WMI GUID ``B642801B-3D21-45DE-90AE-6E86F164FB21``
> +
> +The LENOVO_FAN_TEST_DATA interface provides reference data for self-test of
> +cooling fans.
>  
>  WMI interface description
>  =========================
> @@ -115,3 +122,13 @@ data using the `bmfdec <https://github.com/pali/bmfdec>`_ utility:
>      [WmiDataId(3), read, Description("Data Size.")] uint32 DataSize;
>      [WmiDataId(4), read, Description("Default Value"), WmiSizeIs("DataSize")] uint8 DefaultValue[];
>    };
> +
> +  [WMI, Dynamic, Provider("WmiProv"), Locale("MS\\0x409"), Description("Definition of Fan Test Data"), guid("{B642801B-3D21-45DE-90AE-6E86F164FB21}")]
> +  class LENOVO_FAN_TEST_DATA {
> +    [key, read] string InstanceName;
> +    [read] boolean Active;
> +    [WmiDataId(1), read, Description("Mode.")] uint32 NumOfFans;
> +    [WmiDataId(2), read, Description("Fan ID."), WmiSizeIs("NumOfFans")] uint32 FanId[];
> +    [WmiDataId(3), read, Description("Maximum Fan Speed."), WmiSizeIs("NumOfFans")] uint32 FanMaxSpeed[];
> +    [WmiDataId(4), read, Description("Minumum Fan Speed."), WmiSizeIs("NumOfFans")] uint32 FanMinSpeed[];
> +  };
> diff --git a/drivers/platform/x86/lenovo/wmi-capdata.c b/drivers/platform/x86/lenovo/wmi-capdata.c
> index 08a78dc490f6..9fed162abd17 100644
> --- a/drivers/platform/x86/lenovo/wmi-capdata.c
> +++ b/drivers/platform/x86/lenovo/wmi-capdata.c
> @@ -13,6 +13,10 @@
>   * attribute has multiple pages, one for each of the thermal modes managed by
>   * the Gamezone interface.
>   *
> + * Fan Test Data includes the max/min fan speed RPM for each fan. This is
> + * reference data for self-test. If the fan is in good condition, it is capable
> + * to spin faster than max RPM or slower than min RPM.
> + *
>   * Copyright (C) 2025 Derek J. Clark <derekjohn.clark@...il.com>
>   *   - Initial implementation (formerly named lenovo-wmi-capdata01)
>   *
> @@ -45,6 +49,7 @@
>  
>  #define LENOVO_CAPABILITY_DATA_00_GUID "362A3AFE-3D96-4665-8530-96DAD5BB300E"
>  #define LENOVO_CAPABILITY_DATA_01_GUID "7A8F5407-CB67-4D6E-B547-39B3BE018154"
> +#define LENOVO_FAN_TEST_DATA_GUID "B642801B-3D21-45DE-90AE-6E86F164FB21"
>  
>  #define ACPI_AC_CLASS "ac_adapter"
>  #define ACPI_AC_NOTIFY_STATUS 0x80
> @@ -52,6 +57,7 @@
>  enum lwmi_cd_type {
>  	LENOVO_CAPABILITY_DATA_00,
>  	LENOVO_CAPABILITY_DATA_01,
> +	LENOVO_FAN_TEST_DATA,
>  };
>  
>  #define LWMI_CD_TABLE_ITEM(_type)		\
> @@ -66,6 +72,7 @@ static const struct lwmi_cd_info {
>  } lwmi_cd_table[] = {
>  	LWMI_CD_TABLE_ITEM(LENOVO_CAPABILITY_DATA_00),
>  	LWMI_CD_TABLE_ITEM(LENOVO_CAPABILITY_DATA_01),
> +	LWMI_CD_TABLE_ITEM(LENOVO_FAN_TEST_DATA),
>  };
>  
>  struct lwmi_cd_priv {
> @@ -82,6 +89,7 @@ struct cd_list {
>  	union {
>  		DECLARE_FLEX_ARRAY(struct capdata00, cd00);
>  		DECLARE_FLEX_ARRAY(struct capdata01, cd01);
> +		DECLARE_FLEX_ARRAY(struct capdata_fan, cd_fan);
>  	};
>  };
>  
> @@ -121,6 +129,10 @@ void lwmi_cd_match_add_all(struct device *master, struct component_match **match
>  		return;
>  
>  	for (i = 0; i < ARRAY_SIZE(lwmi_cd_table); i++) {
> +		/* Skip sub-components. */
> +		if (lwmi_cd_table[i].type == LENOVO_FAN_TEST_DATA)
> +			continue;
> +
>  		component_match_add(master, matchptr, lwmi_cd_match,
>  				    (void *)&lwmi_cd_table[i].type);
>  		if (IS_ERR(*matchptr))
> @@ -200,6 +212,9 @@ EXPORT_SYMBOL_NS_GPL(lwmi_cd00_get_data, "LENOVO_WMI_CD");
>  DEF_LWMI_CDXX_GET_DATA(cd01, LENOVO_CAPABILITY_DATA_01, struct capdata01);
>  EXPORT_SYMBOL_NS_GPL(lwmi_cd01_get_data, "LENOVO_WMI_CD");
>  
> +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_CD");
> +
>  /**
>   * lwmi_cd_cache() - Cache all WMI data block information
>   * @priv: lenovo-wmi-capdata driver data.
> @@ -223,6 +238,9 @@ static int lwmi_cd_cache(struct lwmi_cd_priv *priv)
>  		p = &priv->list->cd01[0];
>  		size = sizeof(priv->list->cd01[0]);
>  		break;
> +	case LENOVO_FAN_TEST_DATA:
> +		/* Done by lwmi_cd_alloc() => lwmi_cd_fan_list_alloc_cache(). */
> +		return 0;
>  	default:
>  		return -EINVAL;
>  	}
> @@ -245,6 +263,72 @@ static int lwmi_cd_cache(struct lwmi_cd_priv *priv)
>  	return 0;
>  }
>  
> +/**
> + * lwmi_cd_fan_list_alloc_cache() - Alloc and cache Fan Test Data list
> + * @priv: lenovo-wmi-capdata driver data.
> + * @listptr: Pointer to returned cd_list pointer.
> + *
> + * Return: count of fans found, or an error.
> + */
> +static int lwmi_cd_fan_list_alloc_cache(struct lwmi_cd_priv *priv, struct cd_list **listptr)
> +{
> +	struct cd_list *list;
> +	size_t size;
> +	u32 count;
> +	int idx;
> +
> +	/* Emit unaligned access to u8 buffer with __packed. */
> +	struct cd_fan_block {
> +		u32 nr;
> +		u32 data[]; /* id[nr], max_rpm[nr], min_rpm[nr] */
> +	} __packed * block;
> +
> +	union acpi_object *ret_obj __free(kfree) = wmidev_block_query(priv->wdev, 0);
> +	if (!ret_obj)
> +		return -ENODEV;
> +
> +	if (ret_obj->type == ACPI_TYPE_BUFFER) {
> +		block = (struct cd_fan_block *)ret_obj->buffer.pointer;
> +		size = ret_obj->buffer.length;
> +
> +		count = size >= sizeof(*block) ? block->nr : 0;
> +		if (size < struct_size(block, data, count * 3)) {
> +			dev_warn(&priv->wdev->dev,
> +				 "incomplete fan test data block: %zu < %zu, ignoring\n",
> +				 size, struct_size(block, data, count * 3));
> +			count = 0;
> +		} else if (count > U8_MAX) {

+ limits.h

-- 
 i.

> +			dev_warn(&priv->wdev->dev,
> +				 "too many fans reported: %u > %u, truncating\n",
> +				 count, U8_MAX);
> +			count = U8_MAX;
> +		}
> +	} else {
> +		/*
> +		 * This is usually caused by a dummy ACPI method. Do not return an error
> +		 * as failing to probe this device will result in sub-master device being
> +		 * unbound. This behavior aligns with lwmi_cd_cache().
> +		 */
> +		count = 0;
> +	}
> +
> +	list = devm_kzalloc(&priv->wdev->dev, struct_size(list, cd_fan, count), GFP_KERNEL);
> +	if (!list)
> +		return -ENOMEM;
> +
> +	for (idx = 0; idx < count; idx++) {
> +		/* Do not calculate array index using count, as it may be truncated. */
> +		list->cd_fan[idx] = (struct capdata_fan) {
> +			.id      = block->data[idx],
> +			.max_rpm = block->data[idx + block->nr],
> +			.min_rpm = block->data[idx + (2 * block->nr)],
> +		};
> +	}
> +
> +	*listptr = list;
> +	return count;
> +}
> +
>  /**
>   * lwmi_cd_alloc() - Allocate a cd_list struct in drvdata
>   * @priv: lenovo-wmi-capdata driver data.
> @@ -270,6 +354,12 @@ static int lwmi_cd_alloc(struct lwmi_cd_priv *priv, enum lwmi_cd_type type)
>  	case LENOVO_CAPABILITY_DATA_01:
>  		list_size = struct_size(list, cd01, count);
>  		break;
> +	case LENOVO_FAN_TEST_DATA:
> +		count = lwmi_cd_fan_list_alloc_cache(priv, &list);
> +		if (count < 0)
> +			return count;
> +
> +		goto got_list;
>  	default:
>  		return -EINVAL;
>  	}
> @@ -278,6 +368,7 @@ static int lwmi_cd_alloc(struct lwmi_cd_priv *priv, enum lwmi_cd_type type)
>  	if (!list)
>  		return -ENOMEM;
>  
> +got_list:
>  	ret = devm_mutex_init(&priv->wdev->dev, &list->list_mutex);
>  	if (ret)
>  		return ret;
> @@ -396,6 +487,8 @@ static int lwmi_cd_probe(struct wmi_device *wdev, const void *context)
>  
>  		ret = component_add(&wdev->dev, &lwmi_cd_component_ops);
>  		goto out;
> +	case LENOVO_FAN_TEST_DATA:
> +		goto out;
>  	default:
>  		return -EINVAL;
>  	}
> @@ -419,6 +512,8 @@ static void lwmi_cd_remove(struct wmi_device *wdev)
>  	case LENOVO_CAPABILITY_DATA_01:
>  		component_del(&wdev->dev, &lwmi_cd_component_ops);
>  		break;
> +	case LENOVO_FAN_TEST_DATA:
> +		break;
>  	default:
>  		WARN_ON(1);
>  	}
> @@ -431,6 +526,7 @@ static void lwmi_cd_remove(struct wmi_device *wdev)
>  static const struct wmi_device_id lwmi_cd_id_table[] = {
>  	{ LWMI_CD_WDEV_ID(LENOVO_CAPABILITY_DATA_00) },
>  	{ LWMI_CD_WDEV_ID(LENOVO_CAPABILITY_DATA_01) },
> +	{ LWMI_CD_WDEV_ID(LENOVO_FAN_TEST_DATA) },
>  	{}
>  };
>  
> diff --git a/drivers/platform/x86/lenovo/wmi-capdata.h b/drivers/platform/x86/lenovo/wmi-capdata.h
> index a6d006ef458f..38af4c4e4ef4 100644
> --- a/drivers/platform/x86/lenovo/wmi-capdata.h
> +++ b/drivers/platform/x86/lenovo/wmi-capdata.h
> @@ -26,6 +26,12 @@ struct capdata01 {
>  	u32 max_value;
>  };
>  
> +struct capdata_fan {
> +	u32 id;
> +	u32 min_rpm;
> +	u32 max_rpm;
> +};
> +
>  struct lwmi_cd_binder {
>  	struct cd_list *cd00_list;
>  	struct cd_list *cd01_list;
> @@ -34,5 +40,6 @@ struct lwmi_cd_binder {
>  void lwmi_cd_match_add_all(struct device *master, struct component_match **matchptr);
>  int lwmi_cd00_get_data(struct cd_list *list, u32 attribute_id, struct capdata00 *output);
>  int lwmi_cd01_get_data(struct cd_list *list, u32 attribute_id, struct capdata01 *output);
> +int lwmi_cd_fan_get_data(struct cd_list *list, u32 attribute_id, struct capdata_fan *output);
>  
>  #endif /* !_LENOVO_WMI_CAPDATA_H_ */
> 

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