ACPI: battery: Add the ThinkPad "Not Charging" quirk

The EC/ACPI firmware on Lenovo ThinkPads used to report a status
of "Unknown" when the battery is between the charge start and
charge stop thresholds. On Windows, it reports "Not Charging"
so the quirk has been added to also report correctly.

Now the "status" attribute returns "Not Charging" when the
battery on ThinkPads is not physicaly charging.

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Ognjen Galic <smclt30p@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/battery.c

@@ -74,6 +74,7 @@ static async_cookie_t async_cookie;
 static bool battery_driver_registered;
 static int battery_bix_broken_package;
 static int battery_notification_delay_ms;
+static int battery_quirk_notcharging;
 static int battery_full_discharging;
 static unsigned int cache_time = 1000;
 module_param(cache_time, uint, 0644);
@@ -229,6 +230,8 @@ static int acpi_battery_get_property(struct power_supply *psy,
 			val->intval = POWER_SUPPLY_STATUS_CHARGING;
 		else if (acpi_battery_is_charged(battery))
 			val->intval = POWER_SUPPLY_STATUS_FULL;
+		else if (battery_quirk_notcharging)
+			val->intval = POWER_SUPPLY_STATUS_NOT_CHARGING;
 		else
 			val->intval = POWER_SUPPLY_STATUS_UNKNOWN;
 		break;
@@ -707,7 +710,7 @@ EXPORT_SYMBOL_GPL(battery_hook_register);
  * This function gets called right after the battery sysfs
  * attributes have been added, so that the drivers that
  * define custom sysfs attributes can add their own.
-*/
+ */
 static void battery_hook_add_battery(struct acpi_battery *battery)
 {
 	struct acpi_battery_hook *hook_node;
@@ -1315,6 +1318,12 @@ static int __init battery_full_discharging_quirk(const struct dmi_system_id *d)
 	return 0;
 }
 
+static int __init battery_quirk_not_charging(const struct dmi_system_id *d)
+{
+	battery_quirk_notcharging = 1;
+	return 0;
+}
+
 static const struct dmi_system_id bat_dmi_table[] __initconst = {
 	{
 		.callback = battery_bix_broken_package_quirk,
@@ -1364,6 +1373,19 @@ static const struct dmi_system_id bat_dmi_table[] __initconst = {
 			DMI_MATCH(DMI_PRODUCT_NAME, "UX410UAK"),
 		},
 	},
+	{
+		/*
+		 * On Lenovo ThinkPads the BIOS specification defines
+		 * a state when the bits for charging and discharging
+		 * are both set to 0. That state is "Not Charging".
+		 */
+		.callback = battery_quirk_not_charging,
+		.ident = "Lenovo ThinkPad",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
+			DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad"),
+		},
+	},
 	{},
 };