platform/x86: dell-ddv: Expose the battery health to userspace

The health of a given battery is exposed over the Dell DDV WMI
interface using the "BatteryManufactureAceess" WMI method. The
resulting data contains, among other data, the health status of
the battery.

Expose this value to userspace using the power supply extension
interface.

Tested on a Dell Inspiron 3505.

Signed-off-by: Armin Wolf <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Reviewed-by: Ilpo Järvinen <[e-mail]>
Signed-off-by: Ilpo Järvinen <[e-mail]>

Documentation/wmi/devices/dell-wmi-ddv.rst

···
 WMI method BatteryManufactureAccess()
 -------------------------------------
 
-Returns a manufacture-defined value as an u16.
+Returns the health status of the battery as a u16.
+The health status encoded in the following manner:
+
+ - the third nibble contains the general failure mode
+ - the fourth nibble contains the specific failure code
+
+Valid failure modes are:
+
+ - permanent failure (``0x9``)
+ - overheat failure (``0xa``)
+ - overcurrent failure (``0xb``)
+
+All other failure modes are to be considered normal.
+
+The following failure codes are valid for a permanent failure:
+
+ - fuse blown (``0x0``)
+ - cell imbalance (``0x1``)
+ - overvoltage (``0x2``)
+ - fet failure (``0x3``)
+
+The last two bits of the failure code are to be ignored when the battery
+signals a permanent failure.
+
+The following failure codes a valid for a overheat failure:
+
+ - overheat at start of charging (``0x5``)
+ - overheat during charging (``0x7``)
+ - overheat during discharging (``0x8``)
+
+The following failure codes are valid for a overcurrent failure:
+
+ - overcurrent during charging (``0x6``)
+ - overcurrent during discharging (``0xb``)
 
 WMI method BatteryRelativeStateOfCharge()
 -----------------------------------------

drivers/platform/x86/dell/dell-wmi-ddv.c

···
 #define SBS_MANUFACTURE_MONTH_MASK	GENMASK(8, 5)
 #define SBS_MANUFACTURE_DAY_MASK	GENMASK(4, 0)
 
+#define MA_FAILURE_MODE_MASK			GENMASK(11, 8)
+#define MA_FAILURE_MODE_PERMANENT		0x9
+#define MA_FAILURE_MODE_OVERHEAT		0xA
+#define MA_FAILURE_MODE_OVERCURRENT		0xB
+
+#define MA_PERMANENT_FAILURE_CODE_MASK		GENMASK(13, 12)
+#define MA_PERMANENT_FAILURE_FUSE_BLOWN		0x0
+#define MA_PERMANENT_FAILURE_CELL_IMBALANCE	0x1
+#define MA_PERMANENT_FAILURE_OVERVOLTAGE	0x2
+#define MA_PERMANENT_FAILURE_FET_FAILURE	0x3
+
+#define MA_OVERHEAT_FAILURE_CODE_MASK		GENMASK(15, 12)
+#define MA_OVERHEAT_FAILURE_START		0x5
+#define MA_OVERHEAT_FAILURE_CHARGING		0x7
+#define MA_OVERHEAT_FAILURE_DISCHARGING		0x8
+
+#define MA_OVERCURRENT_FAILURE_CODE_MASK	GENMASK(15, 12)
+#define MA_OVERCURRENT_FAILURE_CHARGING		0x6
+#define MA_OVERCURRENT_FAILURE_DISCHARGING	0xB
+
 #define DELL_EPPID_LENGTH	20
 #define DELL_EPPID_EXT_LENGTH	23
 
···
 	return ret;
 }
 
+static int dell_wmi_ddv_get_health(struct dell_wmi_ddv_data *data, u32 index,
+				   union power_supply_propval *val)
+{
+	u32 value, code;
+	int ret;
+
+	ret = dell_wmi_ddv_query_integer(data->wdev, DELL_DDV_BATTERY_MANUFACTURER_ACCESS, index,
+					 &value);
+	if (ret < 0)
+		return ret;
+
+	switch (FIELD_GET(MA_FAILURE_MODE_MASK, value)) {
+	case MA_FAILURE_MODE_PERMANENT:
+		code = FIELD_GET(MA_PERMANENT_FAILURE_CODE_MASK, value);
+		switch (code) {
+		case MA_PERMANENT_FAILURE_FUSE_BLOWN:
+			val->intval = POWER_SUPPLY_HEALTH_BLOWN_FUSE;
+			return 0;
+		case MA_PERMANENT_FAILURE_CELL_IMBALANCE:
+			val->intval = POWER_SUPPLY_HEALTH_CELL_IMBALANCE;
+			return 0;
+		case MA_PERMANENT_FAILURE_OVERVOLTAGE:
+			val->intval = POWER_SUPPLY_HEALTH_OVERVOLTAGE;
+			return 0;
+		case MA_PERMANENT_FAILURE_FET_FAILURE:
+			val->intval = POWER_SUPPLY_HEALTH_DEAD;
+			return 0;
+		default:
+			dev_notice_once(&data->wdev->dev, "Unknown permanent failure code %u\n",
+					code);
+			val->intval = POWER_SUPPLY_HEALTH_UNSPEC_FAILURE;
+			return 0;
+		}
+	case MA_FAILURE_MODE_OVERHEAT:
+		code = FIELD_GET(MA_OVERHEAT_FAILURE_CODE_MASK, value);
+		switch (code) {
+		case MA_OVERHEAT_FAILURE_START:
+		case MA_OVERHEAT_FAILURE_CHARGING:
+		case MA_OVERHEAT_FAILURE_DISCHARGING:
+			val->intval = POWER_SUPPLY_HEALTH_OVERHEAT;
+			return 0;
+		default:
+			dev_notice_once(&data->wdev->dev, "Unknown overheat failure code %u\n",
+					code);
+			val->intval = POWER_SUPPLY_HEALTH_UNSPEC_FAILURE;
+			return 0;
+		}
+	case MA_FAILURE_MODE_OVERCURRENT:
+		code = FIELD_GET(MA_OVERCURRENT_FAILURE_CODE_MASK, value);
+		switch (code) {
+		case MA_OVERCURRENT_FAILURE_CHARGING:
+		case MA_OVERCURRENT_FAILURE_DISCHARGING:
+			val->intval = POWER_SUPPLY_HEALTH_OVERCURRENT;
+			return 0;
+		default:
+			dev_notice_once(&data->wdev->dev, "Unknown overcurrent failure code %u\n",
+					code);
+			val->intval = POWER_SUPPLY_HEALTH_UNSPEC_FAILURE;
+			return 0;
+		}
+	default:
+		val->intval = POWER_SUPPLY_HEALTH_GOOD;
+		return 0;
+	}
+}
+
 static int dell_wmi_ddv_get_manufacture_date(struct dell_wmi_ddv_data *data, u32 index,
 					     enum power_supply_property psp,
 					     union power_supply_propval *val)
···
 		return ret;
 
 	switch (psp) {
+	case POWER_SUPPLY_PROP_HEALTH:
+		return dell_wmi_ddv_get_health(data, index, val);
 	case POWER_SUPPLY_PROP_TEMP:
 		ret = dell_wmi_ddv_query_integer(data->wdev, DELL_DDV_BATTERY_TEMPERATURE, index,
 						 &value);
···
 }
 
 static const enum power_supply_property dell_wmi_ddv_properties[] = {
+	POWER_SUPPLY_PROP_HEALTH,
 	POWER_SUPPLY_PROP_TEMP,
 	POWER_SUPPLY_PROP_MANUFACTURE_YEAR,
 	POWER_SUPPLY_PROP_MANUFACTURE_MONTH,