power_supply: Add a charge_type property, and use it for olpc driver

This adds a new sysfs file called 'charge_type' which displays the
type of charging (unknown, n/a, trickle charge, or fast charging).

This allows things like battery diagnostics to determine what the
battery/EC is doing without resorting to changing the 'status' sysfs
output.

Signed-off-by: Andres Salomon <dilinger@collabora.co.uk>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>

include/linux/power_supply.h

@@ -38,6 +38,13 @@ enum {
 	POWER_SUPPLY_STATUS_FULL,
 };
 
+enum {
+	POWER_SUPPLY_CHARGE_TYPE_UNKNOWN = 0,
+	POWER_SUPPLY_CHARGE_TYPE_NONE,
+	POWER_SUPPLY_CHARGE_TYPE_TRICKLE,
+	POWER_SUPPLY_CHARGE_TYPE_FAST,
+};
+
 enum {
 	POWER_SUPPLY_HEALTH_UNKNOWN = 0,
 	POWER_SUPPLY_HEALTH_GOOD,
@@ -70,6 +77,7 @@ enum {
 enum power_supply_property {
 	/* Properties of type `int' */
 	POWER_SUPPLY_PROP_STATUS = 0,
+	POWER_SUPPLY_PROP_CHARGE_TYPE,
 	POWER_SUPPLY_PROP_HEALTH,
 	POWER_SUPPLY_PROP_PRESENT,
 	POWER_SUPPLY_PROP_ONLINE,