[PATCH v6 5/7] platform/x86: lenovo-wmi-capdata: Add support for Fan Test Data

[Rong Zhang <i@rong.moe>]

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@rong.moe>
Reviewed-by: Derek J. Clark <derekjohn.clark@gmail.com>
Tested-by: Derek J. Clark <derekjohn.clark@gmail.com>
---
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     | 102 ++++++++++++++++++
 drivers/platform/x86/lenovo/wmi-capdata.h     |   7 ++
 3 files changed, 126 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 29267c373ab3..e6392357395c 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@gmail.com>
  *   - Initial implementation (formerly named lenovo-wmi-capdata01)
  *
@@ -41,6 +45,7 @@
 
 #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
@@ -48,6 +53,7 @@
 enum lwmi_cd_type {
 	LENOVO_CAPABILITY_DATA_00,
 	LENOVO_CAPABILITY_DATA_01,
+	LENOVO_FAN_TEST_DATA,
 };
 
 #define LWMI_CD_TABLE_ITEM(_type)		\
@@ -62,6 +68,7 @@ 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 {
@@ -78,6 +85,7 @@ struct cd_list {
 	union {
 		DECLARE_FLEX_ARRAY(struct capdata00, cd00);
 		DECLARE_FLEX_ARRAY(struct capdata01, cd01);
+		DECLARE_FLEX_ARRAY(struct capdata_fan, cd_fan);
 	};
 };
 
@@ -117,6 +125,10 @@ 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 optional interfaces. */
+		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))
@@ -194,6 +206,9 @@ 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.
@@ -217,6 +232,9 @@ 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;
 	}
@@ -239,6 +257,78 @@ 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)
+{
+	u32 count, *fan_ids, *fan_min_rpms, *fan_max_rpms;
+	union acpi_object *ret_obj __free(kfree) = NULL;
+	struct block { u32 nr; u32 data[]; } *block;
+	struct cd_list *list;
+	size_t size;
+	int idx;
+
+	ret_obj = wmidev_block_query(priv->wdev, 0);
+	if (!ret_obj)
+		return -ENODEV;
+
+	/*
+	 * This is usually caused by a dummy ACPI method. Do not return an error
+	 * as failing to probe this device will result in master driver being
+	 * unbound - this behavior aligns with lwmi_cd_cache().
+	 */
+	if (ret_obj->type != ACPI_TYPE_BUFFER) {
+		count = 0;
+		goto alloc;
+	}
+
+	size = ret_obj->buffer.length;
+	block = (struct block *)ret_obj->buffer.pointer;
+
+	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;
+	}
+
+	if (count == 0)
+		goto alloc;
+
+	if (count > U8_MAX) {
+		dev_warn(&priv->wdev->dev,
+			 "too many fans reported: %u > %u, truncating\n",
+			 count, U8_MAX);
+		count = U8_MAX;
+	}
+
+	fan_ids = &block->data[0];
+	fan_max_rpms = &block->data[count];
+	fan_min_rpms = &block->data[count * 2];
+
+alloc:
+	list = devm_kzalloc(&priv->wdev->dev, struct_size(list, cd_fan, count), GFP_KERNEL);
+	if (!list)
+		return -ENOMEM;
+
+	for (idx = 0; idx < count; idx++) {
+		list->cd_fan[idx] = (struct capdata_fan) {
+			.id = fan_ids[idx],
+			.min_rpm = fan_min_rpms[idx],
+			.max_rpm = fan_max_rpms[idx],
+		};
+	}
+
+	*listptr = list;
+	return count;
+}
+
 /**
  * lwmi_cd_alloc() - Allocate a cd_list struct in drvdata
  * @priv: lenovo-wmi-capdata driver data.
@@ -264,6 +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;
 	}
@@ -272,6 +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;
@@ -390,6 +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;
 	}
@@ -413,6 +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);
 	}
@@ -425,6 +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_ */
-- 
2.51.0