Input: wacom - use a uniq name for the battery device

The current implementation uses "wacom_battery" as a generic name for
batteries. This prevents us to have two Wacom devices with a battery
attached as the power system will complain about the name which is already
registered.

Use an incremental name for each battery attached.

Related bug:
https://sourceforge.net/p/linuxwacom/bugs/248/

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Acked-by: Przemo Firszt <przemo@firszt.eu>
Acked-by: Ping Cheng <pingc@wacom.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/hid/wacom_sys.c

@@ -809,12 +809,16 @@ static int wacom_battery_get_property(struct power_supply *psy,
 static int wacom_initialize_battery(struct wacom *wacom)
 {
 	int error = 0;
+	static atomic_t battery_no = ATOMIC_INIT(0);
+	unsigned long n;
 
 	if (wacom->wacom_wac.features.quirks & WACOM_QUIRK_BATTERY) {
+		n = atomic_inc_return(&battery_no) - 1;
 		wacom->battery.properties = wacom_battery_props;
 		wacom->battery.num_properties = ARRAY_SIZE(wacom_battery_props);
 		wacom->battery.get_property = wacom_battery_get_property;
-		wacom->battery.name = "wacom_battery";
+		sprintf(wacom->wacom_wac.bat_name, "wacom_battery_%ld", n);
+		wacom->battery.name = wacom->wacom_wac.bat_name;
 		wacom->battery.type = POWER_SUPPLY_TYPE_BATTERY;
 		wacom->battery.use_for_apm = 0;
 

drivers/hid/wacom_wac.h

@@ -154,6 +154,7 @@ struct wacom_shared {
 struct wacom_wac {
 	char name[WACOM_NAME_MAX];
 	char pad_name[WACOM_NAME_MAX];
+	char bat_name[WACOM_NAME_MAX];
 	unsigned char data[WACOM_PKGLEN_MAX];
 	int tool[2];
 	int id[2];