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/drivers/input/keyboard/gpio_keys.c b/drivers/input/keyboard/gpio_keys.c
index eb30063..73e58a9 100644
--- a/drivers/input/keyboard/gpio_keys.c
+++ b/drivers/input/keyboard/gpio_keys.c
@@ -324,7 +324,12 @@
 	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 @@
 					 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;