nix (nixos, nixos-hardware) device-tree overlay for LP5012 & oneshot systemd service to set LED color

rpi4-lp5012-leds.nix

{ config, lib, ... }:

let
  cfg = config.hardware.raspberry-pi."4".lp5012-leds;
in {
  options.hardware = {
    raspberry-pi."4".lp5012-leds = {
      enable = lib.mkEnableOption ''
        support for lp50xx activity leds.
      '';
    };
  };

  config = lib.mkIf cfg.enable {
    hardware.raspberry-pi."4".apply-overlays-dtmerge.enable = lib.mkDefault true;

    systemd.services.lp5012-intensity = {
      enable = true;
      wantedBy = [ "multi-user.target" ];
      serviceConfig = {
        Type = "oneshot";
        User = "root";
        Group = "root";
        RemainAfterExit = true;
      };
      script = ''
        if [ -d /sys/class/leds/rgb:power ]; then
          echo "0 255 0" > /sys/class/leds/rgb:power/multi_intensity
          # echo "255" > /sys/class/leds/rgb:power/brightness
        fi

        if [ -d /sys/class/leds/rgb:sd ]; then
          echo "255 255 255" > /sys/class/leds/rgb:sd/multi_intensity
          # echo "255" > /sys/class/leds/rgb:sd/brightness
        fi

        if [ -d /sys/class/leds/rgb:wlan ]; then
          echo "255 255 0" > /sys/class/leds/rgb:wlan/multi_intensity
          # echo "255" > /sys/class/leds/rgb:wlan/brightness
        fi

        if [ -d /sys/class/leds/rgb:bluetooth ]; then
          echo "0 0 255" > /sys/class/leds/rgb:bluetooth/multi_intensity
          # echo "255" > /sys/class/leds/rgb:bluetooth/brightness
        fi
      '';
    };

    hardware.deviceTree = {
      overlays = [
        {
          name = "lp5012-leds-overlay";
          dtsText = ''
            /dts-v1/;
            /plugin/;

            #include <dt-bindings/leds/common.h>

            / {
              compatible = "brcm,bcm2711";

              fragment@0 {
                target = <&i2c1>;
                i2c_bus: __overlay__ {
                  led-controller@14 {
                    compatible = "ti,lp5012";
                    reg = <0x14>;
                    #address-cells = <1>;
                    #size-cells = <0>;

                    multi-led@0 {
                      #address-cells = <1>;
                      #size-cells = <0>;
                      reg = <0>;
                      color = <LED_COLOR_ID_RGB>;
                      function = LED_FUNCTION_POWER;
                      default-state = "off";
                      linux,default-trigger = "default-on";
                      max-brightness = <2>;

                      led@0 {
                        reg = <0>;
                        color = <LED_COLOR_ID_RED>;
                      };

                      led@1 {
                        reg = <1>;
                        color = <LED_COLOR_ID_GREEN>;
                      };

                      led@2 {
                        reg = <2>;
                        color = <LED_COLOR_ID_BLUE>;
                      };
                    };

                    multi-led@1 {
                      #address-cells = <1>;
                      #size-cells = <0>;
                      reg = <1>;
                      color = <LED_COLOR_ID_RGB>;
                      function = LED_FUNCTION_SD;
                      default-state = "off";
                      linux,default-trigger = "mmc0";
                      max-brightness = <2>;

                      led@0 {
                        reg = <0>;
                        color = <LED_COLOR_ID_RED>;
                      };

                      led@1 {
                        reg = <1>;
                        color = <LED_COLOR_ID_GREEN>;
                      };

                      led@2 {
                        reg = <2>;
                        color = <LED_COLOR_ID_BLUE>;
                      };
                    };

                    multi-led@2 {
                      #address-cells = <1>;
                      #size-cells = <0>;
                      reg = <2>;
                      color = <LED_COLOR_ID_RGB>;
                      function = LED_FUNCTION_WLAN;
                      default-state = "off";
                      linux,default-trigger = "rfkill0";
                      max-brightness = <2>;

                      led@0 {
                        reg = <0>;
                        color = <LED_COLOR_ID_RED>;
                      };

                      led@1 {
                        reg = <1>;
                        color = <LED_COLOR_ID_GREEN>;
                      };

                      led@2 {
                        reg = <2>;
                        color = <LED_COLOR_ID_BLUE>;
                      };
                    };

                    multi-led@3 {
                      #address-cells = <1>;
                      #size-cells = <0>;
                      reg = <3>;
                      color = <LED_COLOR_ID_RGB>;
                      function = LED_FUNCTION_BLUETOOTH;
                      default-state = "off";
                      linux,default-trigger = "rfkill1";
                      max-brightness = <2>;

                      led@0 {
                        reg = <0>;
                        color = <LED_COLOR_ID_RED>;
                      };

                      led@1 {
                        reg = <1>;
                        color = <LED_COLOR_ID_GREEN>;
                      };

                      led@2 {
                        reg = <2>;
                        color = <LED_COLOR_ID_BLUE>;
                      };
                    };
                  };
                };
              };
            };
          '';
        }
      ];
    };
  };
}