dm: gpio: Add dm_gpio_request() to manually request a GPIO

This function can be used for testing to manually request a GPIO for use,
without resorting to the legacy GPIO API.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
index b1cf95c..0af599f 100644
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -434,6 +434,18 @@
 			      int flags);
 
 /**
+ * dm_gpio_request() - manually request a GPIO
+ *
+ * Note: This function should only be used for testing / debugging. Instead.
+ * use gpio_request_by_name() to pull GPIOs from the device tree.
+ *
+ * @desc:	GPIO description of GPIO to request (see dm_gpio_lookup_name())
+ * @label:	Label to attach to the GPIO while claimed
+ * @return 0 if OK, -ve on error
+ */
+int dm_gpio_request(struct gpio_desc *desc, const char *label);
+
+/**
  * gpio_get_list_count() - Returns the number of GPIOs in a list
  *
  * Counts the GPIOs in a list. See gpio_request_by_name() for additional