[PATCH] gpio: allow passing NULL to gpio_request_by_line_name() to search all gpio controllers

[Rasmus Villemoes <rasmus.villemoes@prevas.dk>]

The API is more convenient to use if one doesn't have to know upfront
which gpio controller has a line with the name one is searching for,
and arrange to look that device up somehow. Or implement this loop
oneself.

Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
---
 drivers/gpio/gpio-uclass.c | 7 +++++++
 include/asm-generic/gpio.h | 3 ++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpio-uclass.c b/drivers/gpio/gpio-uclass.c
index 0ed32b7217..4912dc8375 100644
--- a/drivers/gpio/gpio-uclass.c
+++ b/drivers/gpio/gpio-uclass.c
@@ -1192,6 +1192,13 @@ int gpio_request_by_line_name(struct udevice *dev, const char *line_name,
 {
 	int ret;
 
+	if (!dev) {
+		uclass_foreach_dev_probe(UCLASS_GPIO, dev)
+			if (!gpio_request_by_line_name(dev, line_name, desc, flags))
+				return 0;
+		return -ENOENT;
+	}
+
 	ret = dev_read_stringlist_search(dev, "gpio-line-names", line_name);
 	if (ret < 0)
 		return ret;
diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
index 81f63f06f1..44ca2458cf 100644
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -587,7 +587,8 @@ int gpio_request_by_name(struct udevice *dev, const char *list_name,
  * This allows boards to implement common behaviours using GPIOs while not
  * requiring specific GPIO offsets be used.
  *
- * @dev:	An instance of a GPIO controller udevice
+ * @dev:        An instance of a GPIO controller udevice, or NULL to search
+ *              all GPIO controller devices
  * @line_name:	The name of the GPIO (e.g. "bmc-secure-boot")
  * @desc:	A GPIO descriptor that is populated with the requested GPIO
  *              upon return
-- 
2.37.2