services: port amdgpu services from private config

modules/services/hardware/amdgpu-pwm.nix

@@ -0,0 +1,29 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+
+  acfg = config.services.amdgpu;
+  cfg = config.services.amdgpu.pwm;
+
+in
+
+{
+  options.services.amdgpu.pwm = {
+    enable = mkEnableOption "amdgpu-pwm";
+  };
+
+  config = mkIf cfg.enable {
+    systemd.services.amdgpu-pwm = {
+      description = "enable manual configuration of AMDGPU fans";
+      wantedBy = [ "default.target" ];
+      script =
+        let
+          enablePwm = card: "echo 1 > /sys/class/drm/${card}/device/hwmon/hwmon1/pwm1_enable";
+        in
+        lib.concatStringsSep "\n" (map enablePwm acfg.cards);
+      serviceConfig.Type = "oneshot";
+    };
+  };
+}