(submitted) input: keyboard: gpio_keys_polled: use gpio lookup table

Support the recently introduced gpio lookup tables for
attaching to gpio lines. So, harcoded gpio numbers aren't
needed anymore.

changes v4:
    * completely rewritten in a much simpler way, now just adding
      a third case (in the button probe loop), where neither oftree
      nor raw gpio number exists.

changes v3:
    * fix printf string in gpio_keys_polled_get_gpiod()
    * fix unused variable 'error' in gpio_keys_polled_get_gpiod()
    * fix uninitialized variable in gpio_keys_polled_get_gpiod_fwnode()

Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: linux-input@vger.kernel.org
Signed-off-by: Enrico Weigelt <info@metux.net>

drivers/input/keyboard/gpio_keys_polled.c

@@ -307,7 +307,7 @@ static int gpio_keys_polled_probe(struct platform_device *pdev)
 				fwnode_handle_put(child);
 				return error;
 			}
-		} else if (gpio_is_valid(button->gpio)) {
+		} else if ((button->gpio > 0) && gpio_is_valid(button->gpio)) {
 			/*
 			 * Legacy GPIO number so request the GPIO here and
 			 * convert it to descriptor.
@@ -333,6 +333,18 @@ static int gpio_keys_polled_probe(struct platform_device *pdev)
 					button->gpio);
 				return -EINVAL;
 			}
+		} else {
+			/* try via gpio lookup table */
+			bdata->gpiod = devm_gpiod_get_index(dev, NULL, i, GPIOF_IN);
+			if (IS_ERR(bdata->gpiod)) {
+				dev_err(dev,
+					"unable to get gpio for button %d: %ld\n",
+					i, PTR_ERR(bdata->gpiod));
+				return PTR_ERR(bdata->gpiod);
+			}
+
+			gpiod_set_consumer_name(bdata->gpiod,
+						button->desc ? : DRV_NAME);
 		}
 
 		bdata->last_state = -1;