0001 # SPDX-License-Identifier: GPL-2.0-only
0002 %YAML 1.2
0003 ---
0004 $id: http://devicetree.org/schemas/leds/backlight/pwm-backlight.yaml#
0005 $schema: http://devicetree.org/meta-schemas/core.yaml#
0006
0007 title: pwm-backlight bindings
0008
0009 maintainers:
0010 - Lee Jones <lee@kernel.org>
0011 - Daniel Thompson <daniel.thompson@linaro.org>
0012 - Jingoo Han <jingoohan1@gmail.com>
0013
0014 properties:
0015 compatible:
0016 const: pwm-backlight
0017
0018 pwms:
0019 maxItems: 1
0020
0021 pwm-names: true
0022
0023 power-supply:
0024 description: regulator for supply voltage
0025
0026 enable-gpios:
0027 description:
0028 Contains a single GPIO specifier for the GPIO which enables and disables
0029 the backlight.
0030 maxItems: 1
0031
0032 post-pwm-on-delay-ms:
0033 description:
0034 Delay in ms between setting an initial (non-zero) PWM and enabling the
0035 backlight using GPIO.
0036
0037 pwm-off-delay-ms:
0038 description:
0039 Delay in ms between disabling the backlight using GPIO and setting PWM
0040 value to 0.
0041
0042 brightness-levels:
0043 description:
0044 Array of distinct brightness levels. Typically these are in the range
0045 from 0 to 255, but any range starting at 0 will do. The actual brightness
0046 level (PWM duty cycle) will be interpolated from these values. 0 means a
0047 0% duty cycle (darkest/off), while the last value in the array represents
0048 a 100% duty cycle (brightest).
0049 $ref: /schemas/types.yaml#/definitions/uint32-array
0050
0051 default-brightness-level:
0052 description:
0053 The default brightness level (index into the array defined by the
0054 "brightness-levels" property).
0055 $ref: /schemas/types.yaml#/definitions/uint32
0056
0057 num-interpolated-steps:
0058 description:
0059 Number of interpolated steps between each value of brightness-levels
0060 table. This way a high resolution pwm duty cycle can be used without
0061 having to list out every possible value in the brightness-level array.
0062 $ref: /schemas/types.yaml#/definitions/uint32
0063
0064 dependencies:
0065 default-brightness-level: [brightness-levels]
0066 num-interpolated-steps: [brightness-levels]
0067
0068 required:
0069 - compatible
0070 - pwms
0071 - power-supply
0072
0073 additionalProperties: false
0074
0075 examples:
0076 - |
0077 backlight {
0078 compatible = "pwm-backlight";
0079 pwms = <&pwm 0 5000000>;
0080
0081 brightness-levels = <0 4 8 16 32 64 128 255>;
0082 default-brightness-level = <6>;
0083
0084 power-supply = <&vdd_bl_reg>;
0085 enable-gpios = <&gpio 58 0>;
0086 post-pwm-on-delay-ms = <10>;
0087 pwm-off-delay-ms = <10>;
0088 };
0089
0090 - |
0091 // Example using num-interpolation-steps:
0092 backlight {
0093 compatible = "pwm-backlight";
0094 pwms = <&pwm 0 5000000>;
0095
0096 brightness-levels = <0 2048 4096 8192 16384 65535>;
0097 num-interpolated-steps = <2048>;
0098 default-brightness-level = <4096>;
0099
0100 power-supply = <&vdd_bl_reg>;
0101 enable-gpios = <&gpio 58 0>;
0102 };
0103
0104 ...
