leds: gpio: Try to lookup gpiod from device

This augments the GPIO lookup code in the GPIO LEDs to
attempt to look up a GPIO descriptor from the device with
index.

This makes it possible to use GPIO machine look-up tables
and stop passing global GPIO numbers through platform data.

Using this we can stepwise convert existing board files
to use machine descriptor tables and then eventually drop
the legacy GPIO support and only include
<linux/gpio/consumer.h> and use descriptors exclusively.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>

drivers/leds/leds-gpio.c

@@ -81,35 +81,6 @@ static int create_gpio_led(const struct gpio_led *template,
 {
 	int ret, state;
 
-	led_dat->gpiod = template->gpiod;
-	if (!led_dat->gpiod) {
-		/*
-		 * This is the legacy code path for platform code that
-		 * still uses GPIO numbers. Ultimately we would like to get
-		 * rid of this block completely.
-		 */
-		unsigned long flags = GPIOF_OUT_INIT_LOW;
-
-		/* skip leds that aren't available */
-		if (!gpio_is_valid(template->gpio)) {
-			dev_info(parent, "Skipping unavailable LED gpio %d (%s)\n",
-					template->gpio, template->name);
-			return 0;
-		}
-
-		if (template->active_low)
-			flags |= GPIOF_ACTIVE_LOW;
-
-		ret = devm_gpio_request_one(parent, template->gpio, flags,
-					    template->name);
-		if (ret < 0)
-			return ret;
-
-		led_dat->gpiod = gpio_to_desc(template->gpio);
-		if (!led_dat->gpiod)
-			return -EINVAL;
-	}
-
 	led_dat->cdev.name = template->name;
 	led_dat->cdev.default_trigger = template->default_trigger;
 	led_dat->can_sleep = gpiod_cansleep(led_dat->gpiod);
@@ -231,6 +202,52 @@ static const struct of_device_id of_gpio_leds_match[] = {
 
 MODULE_DEVICE_TABLE(of, of_gpio_leds_match);
 
+static struct gpio_desc *gpio_led_get_gpiod(struct device *dev, int idx,
+					    const struct gpio_led *template)
+{
+	struct gpio_desc *gpiod;
+	unsigned long flags = GPIOF_OUT_INIT_LOW;
+	int ret;
+
+	/*
+	 * This means the LED does not come from the device tree
+	 * or ACPI, so let's try just getting it by index from the
+	 * device, this will hit the board file, if any and get
+	 * the GPIO from there.
+	 */
+	gpiod = devm_gpiod_get_index(dev, NULL, idx, flags);
+	if (!IS_ERR(gpiod)) {
+		gpiod_set_consumer_name(gpiod, template->name);
+		return gpiod;
+	}
+	if (PTR_ERR(gpiod) != -ENOENT)
+		return gpiod;
+
+	/*
+	 * This is the legacy code path for platform code that
+	 * still uses GPIO numbers. Ultimately we would like to get
+	 * rid of this block completely.
+	 */
+
+	/* skip leds that aren't available */
+	if (!gpio_is_valid(template->gpio))
+		return ERR_PTR(-ENOENT);
+
+	if (template->active_low)
+		flags |= GPIOF_ACTIVE_LOW;
+
+	ret = devm_gpio_request_one(dev, template->gpio, flags,
+				    template->name);
+	if (ret < 0)
+		return ERR_PTR(ret);
+
+	gpiod = gpio_to_desc(template->gpio);
+	if (!gpiod)
+		return ERR_PTR(-EINVAL);
+
+	return gpiod;
+}
+
 static int gpio_led_probe(struct platform_device *pdev)
 {
 	struct gpio_led_platform_data *pdata = dev_get_platdata(&pdev->dev);
@@ -246,7 +263,22 @@ static int gpio_led_probe(struct platform_device *pdev)
 
 		priv->num_leds = pdata->num_leds;
 		for (i = 0; i < priv->num_leds; i++) {
-			ret = create_gpio_led(&pdata->leds[i], &priv->leds[i],
+			const struct gpio_led *template = &pdata->leds[i];
+			struct gpio_led_data *led_dat = &priv->leds[i];
+
+			if (template->gpiod)
+				led_dat->gpiod = template->gpiod;
+			else
+				led_dat->gpiod =
+					gpio_led_get_gpiod(&pdev->dev,
+							   i, template);
+			if (IS_ERR(led_dat->gpiod)) {
+				dev_info(&pdev->dev, "Skipping unavailable LED gpio %d (%s)\n",
+					 template->gpio, template->name);
+				continue;
+			}
+
+			ret = create_gpio_led(template, led_dat,
 					      &pdev->dev, NULL,
 					      pdata->gpio_blink_set);
 			if (ret < 0)