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>

drivers/input/keyboard/gpio_keys.c

@@ -324,7 +324,12 @@ static void gpio_keys_report_event(struct gpio_button_data *bdata)
 	unsigned int type = button->type ?: EV_KEY;
 	int state = (gpio_get_value_cansleep(button->gpio) ? 1 : 0) ^ button->active_low;
 
-	input_event(input, type, button->code, !!state);
+	if (type == EV_ABS) {
+		if (state)
+			input_event(input, type, button->code, button->value);
+	} else {
+		input_event(input, type, button->code, !!state);
+	}
 	input_sync(input);
 }
 
@@ -363,7 +368,7 @@ static int __devinit gpio_keys_setup_key(struct platform_device *pdev,
 					 struct gpio_button_data *bdata,
 					 struct gpio_keys_button *button)
 {
-	char *desc = button->desc ? button->desc : "gpio_keys";
+	const char *desc = button->desc ? button->desc : "gpio_keys";
 	struct device *dev = &pdev->dev;
 	unsigned long irqflags;
 	int irq, error;

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 {