xref: /linux/Documentation/devicetree/bindings/leds/backlight/pwm-backlight.yaml (revision c532de5a67a70f8533d495f8f2aaa9a0491c3ad0) 
1# SPDX-License-Identifier: GPL-2.0-only
2%YAML 1.2
3---
4$id: http://devicetree.org/schemas/leds/backlight/pwm-backlight.yaml#
5$schema: http://devicetree.org/meta-schemas/core.yaml#
6
7title: pwm-backlight
8
9maintainers:
10  - Lee Jones <lee@kernel.org>
11  - Daniel Thompson <daniel.thompson@linaro.org>
12  - Jingoo Han <jingoohan1@gmail.com>
13
14allOf:
15  - $ref: common.yaml#
16
17properties:
18  compatible:
19    const: pwm-backlight
20
21  pwms:
22    maxItems: 1
23
24  pwm-names: true
25
26  power-supply:
27    description: regulator for supply voltage
28
29  enable-gpios:
30    description:
31      Contains a single GPIO specifier for the GPIO which enables and disables
32      the backlight.
33    maxItems: 1
34
35  post-pwm-on-delay-ms:
36    description:
37      Delay in ms between setting an initial (non-zero) PWM and enabling the
38      backlight using GPIO.
39
40  pwm-off-delay-ms:
41    description:
42      Delay in ms between disabling the backlight using GPIO and setting PWM
43      value to 0.
44
45  num-interpolated-steps:
46    description:
47      Number of interpolated steps between each value of brightness-levels
48      table. This way a high resolution pwm duty cycle can be used without
49      having to list out every possible value in the brightness-level array.
50    $ref: /schemas/types.yaml#/definitions/uint32
51
52dependencies:
53  default-brightness-level: [brightness-levels]
54  num-interpolated-steps: [brightness-levels]
55
56required:
57  - compatible
58  - pwms
59
60unevaluatedProperties: false
61
62examples:
63  - |
64    backlight {
65        compatible = "pwm-backlight";
66        pwms = <&pwm 0 5000000>;
67
68        brightness-levels = <0 4 8 16 32 64 128 255>;
69        default-brightness-level = <6>;
70
71        power-supply = <&vdd_bl_reg>;
72        enable-gpios = <&gpio 58 0>;
73        post-pwm-on-delay-ms = <10>;
74        pwm-off-delay-ms = <10>;
75    };
76
77  - |
78    // Example using num-interpolation-steps:
79    backlight {
80        compatible = "pwm-backlight";
81        pwms = <&pwm 0 5000000>;
82
83        brightness-levels = <0 2048 4096 8192 16384 65535>;
84        num-interpolated-steps = <2048>;
85        default-brightness-level = <4096>;
86
87        power-supply = <&vdd_bl_reg>;
88        enable-gpios = <&gpio 58 0>;
89    };
90
91...
92