dt-bindings: backlight: Convert common backlight bindings to DT schema

Convert the common GPIO, LED, and PWM backlight bindings to DT schema
format.

Given there's only 2 common properties and the descriptions are slightly
different, I opted to not create a common backlight schema.

Cc: Lee Jones <lee.jones@linaro.org>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jingoo Han <jingoohan1@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://lore.kernel.org/r/20200630200111.1170742-1-robh@kernel.orgSigned-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/leds/backlight/gpio-backlight.txt

-gpio-backlight bindings
-
-Required properties:
-  - compatible: "gpio-backlight"
-  - gpios: describes the gpio that is used for enabling/disabling the backlight.
-    refer to bindings/gpio/gpio.txt for more details.
-
-Optional properties:
-  - default-on: enable the backlight at boot.
-
-Example:
-	backlight {
-		compatible = "gpio-backlight";
-		gpios = <&gpio3 4 GPIO_ACTIVE_HIGH>;
-		default-on;
-	};

Documentation/devicetree/bindings/leds/backlight/gpio-backlight.yaml

+# SPDX-License-Identifier: GPL-2.0-only
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/leds/backlight/gpio-backlight.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: gpio-backlight bindings
+
+maintainers:
+  - Lee Jones <lee.jones@linaro.org>
+  - Daniel Thompson <daniel.thompson@linaro.org>
+  - Jingoo Han <jingoohan1@gmail.com>
+
+properties:
+  compatible:
+    const: gpio-backlight
+
+  gpios:
+    description: The gpio that is used for enabling/disabling the backlight.
+    maxItems: 1
+
+  default-on:
+    description: enable the backlight at boot.
+    type: boolean
+
+required:
+  - compatible
+  - gpios
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    backlight {
+        compatible = "gpio-backlight";
+        gpios = <&gpio3 4 GPIO_ACTIVE_HIGH>;
+        default-on;
+    };
+
+...

Documentation/devicetree/bindings/leds/backlight/led-backlight.txt

-led-backlight bindings
-
-This binding is used to describe a basic backlight device made of LEDs.
-It can also be used to describe a backlight device controlled by the output of
-a LED driver.
-
-Required properties:
-  - compatible: "led-backlight"
-  - leds: a list of LEDs
-
-Optional properties:
-  - brightness-levels: Array of distinct brightness levels. The levels must be
-                       in the range accepted by the underlying LED devices.
-                       This is used to translate a backlight brightness level
-                       into a LED brightness level. If it is not provided, the
-                       identity mapping is used.
-
-  - default-brightness-level: The default brightness level.
-
-Example:
-
-	backlight {
-		compatible = "led-backlight";
-
-		leds = <&led1>, <&led2>;
-		brightness-levels = <0 4 8 16 32 64 128 255>;
-		default-brightness-level = <6>;
-	};

Documentation/devicetree/bindings/leds/backlight/led-backlight.yaml

+# SPDX-License-Identifier: GPL-2.0-only
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/leds/backlight/led-backlight.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: led-backlight bindings
+
+maintainers:
+  - Lee Jones <lee.jones@linaro.org>
+  - Daniel Thompson <daniel.thompson@linaro.org>
+  - Jingoo Han <jingoohan1@gmail.com>
+
+description:
+  This binding is used to describe a basic backlight device made of LEDs. It
+  can also be used to describe a backlight device controlled by the output of
+  a LED driver.
+
+properties:
+  compatible:
+    const: led-backlight
+
+  leds:
+    description: A list of LED nodes
+    $ref: /schemas/types.yaml#/definitions/phandle-array
+
+  brightness-levels:
+    description:
+      Array of distinct brightness levels. The levels must be in the range
+      accepted by the underlying LED devices. This is used to translate a
+      backlight brightness level into a LED brightness level. If it is not
+      provided, the identity mapping is used.
+    $ref: /schemas/types.yaml#/definitions/uint32-array
+
+  default-brightness-level:
+    description:
+      The default brightness level (index into the array defined by the
+      "brightness-levels" property).
+    $ref: /schemas/types.yaml#/definitions/uint32
+
+required:
+  - compatible
+  - leds
+
+additionalProperties: false
+
+examples:
+  - |
+    backlight {
+        compatible = "led-backlight";
+
+        leds = <&led1>, <&led2>;
+        brightness-levels = <0 4 8 16 32 64 128 255>;
+        default-brightness-level = <6>;
+    };
+
+...

Documentation/devicetree/bindings/leds/backlight/pwm-backlight.txt

-pwm-backlight bindings
-
-Required properties:
-  - compatible: "pwm-backlight"
-  - pwms: OF device-tree PWM specification (see PWM binding[0])
-  - power-supply: regulator for supply voltage
-
-Optional properties:
-  - pwm-names: a list of names for the PWM devices specified in the
-               "pwms" property (see PWM binding[0])
-  - enable-gpios: contains a single GPIO specifier for the GPIO which enables
-                  and disables the backlight (see GPIO binding[1])
-  - post-pwm-on-delay-ms: Delay in ms between setting an initial (non-zero) PWM
-                          and enabling the backlight using GPIO.
-  - pwm-off-delay-ms: Delay in ms between disabling the backlight using GPIO
-                      and setting PWM value to 0.
-  - brightness-levels: Array of distinct brightness levels. Typically these
-                       are in the range from 0 to 255, but any range starting at
-                       0 will do. The actual brightness level (PWM duty cycle)
-                       will be interpolated from these values. 0 means a 0% duty
-                       cycle (darkest/off), while the last value in the array
-                       represents a 100% duty cycle (brightest).
-  - default-brightness-level: The default brightness level (index into the
-                              array defined by the "brightness-levels" property).
-  - num-interpolated-steps: Number of interpolated steps between each value
-                            of brightness-levels table. This way a high
-                            resolution pwm duty cycle can be used without
-                            having to list out every possible value in the
-                            brightness-level array.
-
-[0]: Documentation/devicetree/bindings/pwm/pwm.txt
-[1]: Documentation/devicetree/bindings/gpio/gpio.txt
-
-Example:
-
-	backlight {
-		compatible = "pwm-backlight";
-		pwms = <&pwm 0 5000000>;
-
-		brightness-levels = <0 4 8 16 32 64 128 255>;
-		default-brightness-level = <6>;
-
-		power-supply = <&vdd_bl_reg>;
-		enable-gpios = <&gpio 58 0>;
-		post-pwm-on-delay-ms = <10>;
-		pwm-off-delay-ms = <10>;
-	};
-
-Example using num-interpolation-steps:
-
-	backlight {
-		compatible = "pwm-backlight";
-		pwms = <&pwm 0 5000000>;
-
-		brightness-levels = <0 2048 4096 8192 16384 65535>;
-		num-interpolated-steps = <2048>;
-		default-brightness-level = <4096>;
-
-		power-supply = <&vdd_bl_reg>;
-		enable-gpios = <&gpio 58 0>;
-	};

Documentation/devicetree/bindings/leds/backlight/pwm-backlight.yaml

+# SPDX-License-Identifier: GPL-2.0-only
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/leds/backlight/pwm-backlight.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: pwm-backlight bindings
+
+maintainers:
+  - Lee Jones <lee.jones@linaro.org>
+  - Daniel Thompson <daniel.thompson@linaro.org>
+  - Jingoo Han <jingoohan1@gmail.com>
+
+properties:
+  compatible:
+    const: pwm-backlight
+
+  pwms:
+    maxItems: 1
+
+  pwm-names: true
+
+  power-supply:
+    description: regulator for supply voltage
+
+  enable-gpios:
+    description:
+      Contains a single GPIO specifier for the GPIO which enables and disables
+      the backlight.
+    maxItems: 1
+
+  post-pwm-on-delay-ms:
+    description:
+      Delay in ms between setting an initial (non-zero) PWM and enabling the
+      backlight using GPIO.
+
+  pwm-off-delay-ms:
+    description:
+      Delay in ms between disabling the backlight using GPIO and setting PWM
+      value to 0.
+
+  brightness-levels:
+    description:
+      Array of distinct brightness levels. Typically these are in the range
+      from 0 to 255, but any range starting at 0 will do. The actual brightness
+      level (PWM duty cycle) will be interpolated from these values. 0 means a
+      0% duty cycle (darkest/off), while the last value in the array represents
+      a 100% duty cycle (brightest).
+    $ref: /schemas/types.yaml#/definitions/uint32-array
+
+  default-brightness-level:
+    description:
+      The default brightness level (index into the array defined by the
+      "brightness-levels" property).
+    $ref: /schemas/types.yaml#/definitions/uint32
+
+  num-interpolated-steps:
+    description:
+      Number of interpolated steps between each value of brightness-levels
+      table. This way a high resolution pwm duty cycle can be used without
+      having to list out every possible value in the brightness-level array.
+    $ref: /schemas/types.yaml#/definitions/uint32
+
+dependencies:
+  default-brightness-level: [brightness-levels]
+  num-interpolated-steps: [brightness-levels]
+
+required:
+  - compatible
+  - pwms
+  - power-supply
+
+additionalProperties: false
+
+examples:
+  - |
+    backlight {
+        compatible = "pwm-backlight";
+        pwms = <&pwm 0 5000000>;
+
+        brightness-levels = <0 4 8 16 32 64 128 255>;
+        default-brightness-level = <6>;
+
+        power-supply = <&vdd_bl_reg>;
+        enable-gpios = <&gpio 58 0>;
+        post-pwm-on-delay-ms = <10>;
+        pwm-off-delay-ms = <10>;
+    };
+
+  - |
+    // Example using num-interpolation-steps:
+    backlight {
+        compatible = "pwm-backlight";
+        pwms = <&pwm 0 5000000>;
+
+        brightness-levels = <0 2048 4096 8192 16384 65535>;
+        num-interpolated-steps = <2048>;
+        default-brightness-level = <4096>;
+
+        power-supply = <&vdd_bl_reg>;
+        enable-gpios = <&gpio 58 0>;
+    };
+
+...