ACPI Battery: Added capacity

Added Capacity field, which is a pre-defined power_supply
property. Calculating capacity using current charge/energy and
full charge/energy.
Some user mode implementations are relying on capacity field to
show battery strength and power down decision.

Signed-off-by: srinivas pandruvada <srinivas.pandruvada@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/acpi/battery.c

@@ -250,6 +250,13 @@ static int acpi_battery_get_property(struct power_supply *psy,
 		else
 			val->intval = battery->capacity_now * 1000;
 		break;
+	case POWER_SUPPLY_PROP_CAPACITY:
+		if (battery->capacity_now && battery->full_charge_capacity)
+			val->intval = battery->capacity_now * 100/
+					battery->full_charge_capacity;
+		else
+			val->intval = 0;
+		break;
 	case POWER_SUPPLY_PROP_MODEL_NAME:
 		val->strval = battery->model_number;
 		break;
@@ -276,6 +283,7 @@ static enum power_supply_property charge_battery_props[] = {
 	POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN,
 	POWER_SUPPLY_PROP_CHARGE_FULL,
 	POWER_SUPPLY_PROP_CHARGE_NOW,
+	POWER_SUPPLY_PROP_CAPACITY,
 	POWER_SUPPLY_PROP_MODEL_NAME,
 	POWER_SUPPLY_PROP_MANUFACTURER,
 	POWER_SUPPLY_PROP_SERIAL_NUMBER,
@@ -292,6 +300,7 @@ static enum power_supply_property energy_battery_props[] = {
 	POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN,
 	POWER_SUPPLY_PROP_ENERGY_FULL,
 	POWER_SUPPLY_PROP_ENERGY_NOW,
+	POWER_SUPPLY_PROP_CAPACITY,
 	POWER_SUPPLY_PROP_MODEL_NAME,
 	POWER_SUPPLY_PROP_MANUFACTURER,
 	POWER_SUPPLY_PROP_SERIAL_NUMBER,