dt-bindings: leds: Add generic LED consumer documentation

Introduce common generic led consumer binding, where consumer defines
led(s) by phandle, as opposed to trigger-source binding where the
trigger source is defined in led itself.

Add already used in some schemas 'leds' parameter which expects
phandle-array. Additionally, introduce 'led-names' which could be used
by consumers to map LED devices to their respective functions.

Signed-off-by: Aleksandrs Vinarskis <[email protected]>
Reviewed-by: "Rob Herring (Arm)" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Lee Jones <[email protected]>

Author: alexVinarskis

Documentation/devicetree/bindings/leds/leds-consumer.yaml

@@ -0,0 +1,67 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/leds/leds-consumer.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Common leds consumer
+
+maintainers:
+  - Aleksandrs Vinarskis <[email protected]>
+
+description:
+  Some LED defined in DT are required by other DT consumers, for example
+  v4l2 subnode may require privacy or flash LED. Unlike trigger-source
+  approach which is typically used as 'soft' binding, referencing LED
+  devices by phandle makes things simpler when 'hard' binding is desired.
+
+  Document LED properties that its consumers may define.
+
+select: true
+
+properties:
+  leds:
+    oneOf:
+      - type: object
+      - $ref: /schemas/types.yaml#/definitions/phandle-array
+        description:
+          A list of LED device(s) required by a particular consumer.
+        items:
+          maxItems: 1
+
+  led-names:
+    description:
+      A list of device name(s). Used to map LED devices to their respective
+      functions, when consumer requires more than one LED.
+
+additionalProperties: true
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/leds/common.h>
+
+    leds {
+        compatible = "gpio-leds";
+
+        privacy_led: privacy-led {
+            color = <LED_COLOR_ID_RED>;
+            default-state = "off";
+            function = LED_FUNCTION_INDICATOR;
+            gpios = <&tlmm 110 GPIO_ACTIVE_HIGH>;
+        };
+    };
+
+    i2c {
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      v4l2_node: camera@36 {
+        reg = <0x36>;
+
+        leds = <&privacy_led>;
+        led-names = "privacy";
+      };
+    };
+
+...