power: supply: core: add manufacture date properties

Some smart batteries store their manufacture date, which is
useful to identify the battery and/or to know about the cell
quality.

Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

Documentation/ABI/testing/sysfs-class-power

@@ -680,3 +680,31 @@ Description:
 		Valid values:
 		- 1: enabled
 		- 0: disabled
+
+What:		/sys/class/power_supply/<supply_name>/manufacture_year
+Date:		January 2020
+Contact:	linux-pm@vger.kernel.org
+Description:
+		Reports the year (following Gregorian calendar) when the device has been
+		manufactured.
+
+		Access: Read
+		Valid values: Reported as integer
+
+What:		/sys/class/power_supply/<supply_name>/manufacture_month
+Date:		January 2020
+Contact:	linux-pm@vger.kernel.org
+Description:
+		Reports the month when the device has been manufactured.
+
+		Access: Read
+		Valid values: 1-12
+
+What:		/sys/class/power_supply/<supply_name>/manufacture_day
+Date:		January 2020
+Contact:	linux-pm@vger.kernel.org
+Description:
+		Reports the day of month when the device has been manufactured.
+
+		Access: Read
+		Valid values: 1-31

drivers/power/supply/power_supply_sysfs.c

@@ -198,6 +198,9 @@ static struct power_supply_attr power_supply_attrs[] = {
 	POWER_SUPPLY_ATTR(PRECHARGE_CURRENT),
 	POWER_SUPPLY_ATTR(CHARGE_TERM_CURRENT),
 	POWER_SUPPLY_ATTR(CALIBRATE),
+	POWER_SUPPLY_ATTR(MANUFACTURE_YEAR),
+	POWER_SUPPLY_ATTR(MANUFACTURE_MONTH),
+	POWER_SUPPLY_ATTR(MANUFACTURE_DAY),
 	/* Properties of type `const char *' */
 	POWER_SUPPLY_ATTR(MODEL_NAME),
 	POWER_SUPPLY_ATTR(MANUFACTURER),

include/linux/power_supply.h

@@ -159,6 +159,9 @@ enum power_supply_property {
 	POWER_SUPPLY_PROP_PRECHARGE_CURRENT,
 	POWER_SUPPLY_PROP_CHARGE_TERM_CURRENT,
 	POWER_SUPPLY_PROP_CALIBRATE,
+	POWER_SUPPLY_PROP_MANUFACTURE_YEAR,
+	POWER_SUPPLY_PROP_MANUFACTURE_MONTH,
+	POWER_SUPPLY_PROP_MANUFACTURE_DAY,
 	/* Properties of type `const char *' */
 	POWER_SUPPLY_PROP_MODEL_NAME,
 	POWER_SUPPLY_PROP_MANUFACTURER,