nixos-hardware/raspberry-pi/4/pwm0.nix

{ config, lib, ... }:

let
  cfg = config.hardware.raspberry-pi."4".pwm0;
in
{
  options.hardware = {
    raspberry-pi."4".pwm0 = {
      enable = lib.mkEnableOption ''
        Enable support for the hardware pwm0 channel on GPIO_18
      '';
    };
  };

  config = lib.mkIf cfg.enable {
    hardware.deviceTree = {
      overlays = [
        {
          name = "pwm-overlay";
          dtsText = ''
            /dts-v1/;
            /plugin/;
            / {
              compatible = "brcm,bcm2711";

              fragment@0 {
                target = <&gpio>;
                __overlay__ {
                  pwm_pins: pwm_pins {
                    brcm,pins = <18>;
                    brcm,function = <2>; /* Alt5 */
                  };
                };
              };

              fragment@1 {
                target = <&pwm>;
                __overlay__ {
                  pinctrl-names = "default";
                  assigned-clock-rates = <100000000>;
                  status = "okay";
                  pinctrl-0 = <&pwm_pins>;
                };
              };

            };
          '';
        }
      ];
    };
  };
}