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+# 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>;
+ };
+
+...