gpiolib: of: Allow "trigger-sources" to reference a GPIO

The "trigger-sources" phandle used for LED triggers are special:
the DT bindings mandate that such triggers have the same phandle
references no matter what the trigger is. A GPIO is just another
kind of device that can trigger a LED.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

1 files changed, 28 insertions, 0 deletions

diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index 58c0bbe9d569..a904586c3c5f 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -620,6 +620,33 @@ static struct gpio_desc *of_find_mt2701_gpio(struct device_node *np,
 	return desc;
 }
 
+/*
+ * Trigger sources are special, they allow us to use any GPIO as a LED trigger
+ * and have the name "trigger-sources" no matter which kind of phandle it is
+ * pointing to, whether to a GPIO, a USB host, a network PHY etc. So in this case
+ * we allow looking something up that is not named "foo-gpios".
+ */
+static struct gpio_desc *of_find_trigger_gpio(struct device_node *np,
+					      const char *con_id,
+					      unsigned int idx,
+					      enum of_gpio_flags *of_flags)
+{
+	struct gpio_desc *desc;
+
+	if (!IS_ENABLED(CONFIG_LEDS_TRIGGER_GPIO))
+		return ERR_PTR(-ENOENT);
+
+	if (!con_id || strcmp(con_id, "trigger-sources"))
+		return ERR_PTR(-ENOENT);
+
+	desc = of_get_named_gpiod_flags(np, con_id, idx, of_flags);
+	if (!gpiod_not_found(desc))
+		pr_debug("%s is used as a trigger\n", of_node_full_name(np));
+
+	return desc;
+}
+
+
 typedef struct gpio_desc *(*of_find_gpio_quirk)(struct device_node *np,
 						const char *con_id,
 						unsigned int idx,
@@ -627,6 +654,7 @@ typedef struct gpio_desc *(*of_find_gpio_quirk)(struct device_node *np,
 static const of_find_gpio_quirk of_find_gpio_quirks[] = {
 	of_find_gpio_rename,
 	of_find_mt2701_gpio,
+	of_find_trigger_gpio,
 	NULL
 };