Input: gpio_keys - add support for EV_ABS

With this patch you can setup a group of GPIOs representing a specific
position on an EV_ABS axis.

Signed-off-by: Alexander Stein <alexander.stein@informatik.tu-chemnitz.de>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
diff --git a/include/linux/gpio_keys.h b/include/linux/gpio_keys.h
index dd1a56f..3204edf 100644
--- a/include/linux/gpio_keys.h
+++ b/include/linux/gpio_keys.h
@@ -3,14 +3,15 @@
 
 struct gpio_keys_button {
 	/* Configuration parameters */
-	int code;		/* input event code (KEY_*, SW_*) */
+	unsigned int code;	/* input event code (KEY_*, SW_*) */
 	int gpio;
 	int active_low;
-	char *desc;
-	int type;		/* input event type (EV_KEY, EV_SW) */
+	const char *desc;
+	unsigned int type;	/* input event type (EV_KEY, EV_SW, EV_ABS) */
 	int wakeup;		/* configure the button as a wake-up source */
 	int debounce_interval;	/* debounce ticks interval in msecs */
 	bool can_disable;
+	int value;		/* axis value for EV_ABS */
 };
 
 struct gpio_keys_platform_data {