leds: led-class: Add Device Tree support to led_get()

Add 'name' argument to of_led_get() such that it can lookup LEDs in
devicetree by either name or index.

And use this modified function to add devicetree support to the generic
(non devicetree specific) [devm_]led_get() function.

This uses the standard devicetree pattern of adding a -names string array
to map names to the indexes for an array of resources.

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Hans de Goede <hansg@kernel.org>
Signed-off-by: Aleksandrs Vinarskis <alex@vinarskis.com>
Link: https://lore.kernel.org/r/20250910-leds-v5-3-bb90a0f897d5@vinarskis.com
Signed-off-by: Lee Jones <lee@kernel.org>

Author: Hans de Goede

drivers/leds/led-class.c

@@ -252,15 +252,23 @@ static const struct class leds_class = {
  * of_led_get() - request a LED device via the LED framework
  * @np: device node to get the LED device from
  * @index: the index of the LED
+ * @name: the name of the LED used to map it to its function, if present
  *
  * Returns the LED device parsed from the phandle specified in the "leds"
  * property of a device tree node or a negative error-code on failure.
  */
-static struct led_classdev *of_led_get(struct device_node *np, int index)
+static struct led_classdev *of_led_get(struct device_node *np, int index,
+				       const char *name)
 {
 	struct device *led_dev;
 	struct device_node *led_node;
 
+	/*
+	 * For named LEDs, first look up the name in the "led-names" property.
+	 * If it cannot be found, then of_parse_phandle() will propagate the error.
+	 */
+	if (name)
+		index = of_property_match_string(np, "led-names", name);
 	led_node = of_parse_phandle(np, "leds", index);
 	if (!led_node)
 		return ERR_PTR(-ENOENT);
@@ -324,7 +332,7 @@ struct led_classdev *__must_check devm_of_led_get(struct device *dev,
 	if (!dev)
 		return ERR_PTR(-EINVAL);
 
-	led = of_led_get(dev->of_node, index);
+	led = of_led_get(dev->of_node, index, NULL);
 	if (IS_ERR(led))
 		return led;
 
@@ -342,9 +350,14 @@ EXPORT_SYMBOL_GPL(devm_of_led_get);
 struct led_classdev *led_get(struct device *dev, char *con_id)
 {
 	struct led_lookup_data *lookup;
+	struct led_classdev *led_cdev;
 	const char *provider = NULL;
 	struct device *led_dev;
 
+	led_cdev = of_led_get(dev->of_node, -1, con_id);
+	if (!IS_ERR(led_cdev) || PTR_ERR(led_cdev) != -ENOENT)
+		return led_cdev;
+
 	mutex_lock(&leds_lookup_lock);
 	list_for_each_entry(lookup, &leds_lookup_list, list) {
 		if (!strcmp(lookup->dev_id, dev_name(dev)) &&