dt-bindings: backlight: add TI LP8864/LP8866 LED-backlight drivers

Add bindings for Texas Instruments' LP8864/LP8866 LED-backlight drivers.
Note that multiple channels in these models are used for load-balancing and
brightness is controlled gobally, so from a user perspective it's only one
LED.

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
Link: https://lore.kernel.org/r/20241218210829.73191-2-alexander.sverdlin@siemens.com
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>

Documentation/devicetree/bindings/leds/backlight/ti,lp8864.yaml

@@ -0,0 +1,80 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/leds/backlight/ti,lp8864.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Texas Instruments - LP8864/LP8866 4/6-Channel LED Driver family
+
+maintainers:
+  - Andrew Davis <afd@ti.com>
+  - Alexander Sverdlin <alexander.sverdlin@siemens.com>
+
+description: |
+  LP8866-Q1, LP8866S-Q1, LP8864-Q1, LP8864S-Q1 are display LED-backlight drivers
+  with 4/6 channels. LED brightness can be controlled globally through the I2C
+  interface or PWM input.
+
+  For more product information please see the links below:
+    https://www.ti.com/product/LP8864-Q1
+    https://www.ti.com/product/LP8864S-Q1
+    https://www.ti.com/product/LP8866-Q1
+    https://www.ti.com/product/LP8866S-Q1
+
+properties:
+  compatible:
+    const: ti,lp8864
+
+  reg:
+    maxItems: 1
+    description: I2C slave address
+
+  enable-gpios:
+    maxItems: 1
+    description: GPIO pin to enable (active high) / disable the device
+
+  vled-supply:
+    description: LED supply
+
+  led:
+    type: object
+    $ref: common.yaml#
+    properties:
+      function: true
+      color: true
+      label: true
+      linux,default-trigger: true
+
+    additionalProperties: false
+
+required:
+  - compatible
+  - reg
+  - led
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/leds/common.h>
+
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        led-controller@3a {
+            compatible = "ti,lp8864";
+            reg = <0x3a>;
+            enable-gpios = <&gpio1 28 GPIO_ACTIVE_HIGH>;
+            vled-supply = <&vbatt>;
+
+            led {
+                function = LED_FUNCTION_BACKLIGHT;
+                color = <LED_COLOR_ID_WHITE>;
+                linux,default-trigger = "backlight";
+            };
+        };
+    };
+
+...