dt-bindings: backlight: Add Kinetic KTD2801 binding

KTD2801 is a LED backlight driver IC found in samsung,coreprimevelte.
The brightness can be set using PWM or the ExpressWire protocol. Add
a DT binding for the KTD2801.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Duje Mihanović <duje.mihanovic@skole.hr>
Link: https://lore.kernel.org/r/20240125-ktd2801-v5-3-e22da232a825@skole.hr
Signed-off-by: Lee Jones <lee@kernel.org>

Documentation/devicetree/bindings/leds/backlight/kinetic,ktd2801.yaml

@@ -0,0 +1,46 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/leds/backlight/kinetic,ktd2801.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Kinetic Technologies KTD2801 one-wire backlight
+
+maintainers:
+  - Duje Mihanović <duje.mihanovic@skole.hr>
+
+description: |
+  The Kinetic Technologies KTD2801 is a LED backlight driver controlled
+  by a single GPIO line. The driver can be controlled with a PWM signal
+  or by pulsing the GPIO line to set the backlight level. This is called
+  "ExpressWire".
+
+allOf:
+  - $ref: common.yaml#
+
+properties:
+  compatible:
+    const: kinetic,ktd2801
+
+  ctrl-gpios:
+    maxItems: 1
+
+  default-brightness: true
+  max-brightness: true
+
+required:
+  - compatible
+  - ctrl-gpios
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    backlight {
+        compatible = "kinetic,ktd2801";
+        ctrl-gpios = <&gpio 97 GPIO_ACTIVE_HIGH>;
+        max-brightness = <210>;
+        default-brightness = <100>;
+    };