power: supply: core: add POWER_SUPPLY_HEALTH_NO_BATTERY

Some chargers can keep the system powered from the mains even when no
battery is present. It this case none of the currently defined health
statuses applies. Add a new status to report that no battery is present.

Suggested-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

Documentation/ABI/testing/sysfs-class-power

@@ -413,7 +413,7 @@ Description:
 			      "Over voltage", "Unspecified failure", "Cold",
 			      "Watchdog timer expire", "Safety timer expire",
 			      "Over current", "Calibration required", "Warm",
-			      "Cool", "Hot"
+			      "Cool", "Hot", "No battery"
 
 What:		/sys/class/power_supply/<supply_name>/precharge_current
 Date:		June 2017

drivers/power/supply/power_supply_sysfs.c

@@ -106,6 +106,7 @@ static const char * const POWER_SUPPLY_HEALTH_TEXT[] = {
 	[POWER_SUPPLY_HEALTH_WARM]		    = "Warm",
 	[POWER_SUPPLY_HEALTH_COOL]		    = "Cool",
 	[POWER_SUPPLY_HEALTH_HOT]		    = "Hot",
+	[POWER_SUPPLY_HEALTH_NO_BATTERY]	    = "No battery",
 };
 
 static const char * const POWER_SUPPLY_TECHNOLOGY_TEXT[] = {

include/linux/power_supply.h

@@ -66,6 +66,7 @@ enum {
 	POWER_SUPPLY_HEALTH_WARM,
 	POWER_SUPPLY_HEALTH_COOL,
 	POWER_SUPPLY_HEALTH_HOT,
+	POWER_SUPPLY_HEALTH_NO_BATTERY,
 };
 
 enum {