Input: gpio_keys - fall back to platform_get_irq() for interrupt-only keys

To allow transitioning away from gpio-keys platform data attempt to
retrieve IRQ for interrupt-only keys using platform_get_irq_optional()
if interrupt is not specified in platform data.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/keyboard/gpio_keys.c

diff --git a/drivers/input/keyboard/gpio_keys.c b/drivers/input/keyboard/gpio_keys.c
index 5e87577..e196174 100644
--- a/drivers/input/keyboard/gpio_keys.c
+++ b/drivers/input/keyboard/gpio_keys.c
@@ -616,12 +616,19 @@ static int gpio_keys_setup_key(struct platform_device *pdev,
 			break;
 		}
 	} else {
-		if (!button->irq) {
-			dev_err(dev, "Found button without gpio or irq\n");
-			return -EINVAL;
-		}
+		if (button->irq) {
+			bdata->irq = button->irq;
+		} else {
+			irq = platform_get_irq_optional(pdev, idx);
+			if (irq < 0) {
+				error = irq;
+				return dev_err_probe(dev, error,
+						     "Unable to determine IRQ# for button #%d",
+						     idx);
+			}
 
-		bdata->irq = button->irq;
+			bdata->irq = irq;
+		}
 
 		if (button->type && button->type != EV_KEY) {
 			dev_err(dev, "Only EV_KEY allowed for IRQ buttons.\n");