purism/librem/5r4: make it usuable without an overlay

In larger installations nixpkgs.overlays adds significant overhead
because it's harder to share nixpkgs between different NixOS machines
i.e. using nixpkgs.pkgs

purism/librem/5r4/audio.nix

@@ -9,7 +9,7 @@
       enable = true;
       # this is required to correctly configure the modem as PA source/sink
       extraConfig = ''
-        .include ${pkgs.librem5-base}/etc/pulse/librem5.pa
+        .include ${config.hardware.librem5.package}/etc/pulse/librem5.pa
       '';
     };
 

purism/librem/5r4/default.nix

@@ -1,8 +1,15 @@
 { config, pkgs, lib, ... }:
-let cfg = config.hardware.librem5;
+let
+  cfg = config.hardware.librem5;
+  linuxPackages_librem5 = pkgs.linuxPackagesFor (pkgs.callPackage ./kernel.nix { });
+  ubootLibrem5 = pkgs.callPackage ./u-boot { };
 in {
   options = {
     hardware.librem5 = {
+      package = lib.mkOption {
+        type = lib.types.package;
+        default = pkgs.callPackage ./librem5-base { };
+      };
       wifiCard = lib.mkOption {
         type = lib.types.enum [ "redpine" "sparklan" "none" ];
         description = lib.mdDoc ''
@@ -42,15 +49,6 @@ in {
       lockdownFix = lib.mkDefault true;
     };
 
-    nixpkgs.overlays = [
-      (import ./kernel)
-      (final: prev: {
-        ubootLibrem5 = final.callPackage ./u-boot { };
-
-        librem5-base = final.callPackage ./librem5-base { };
-      })
-    ];
-
     boot = {
       kernelParams = [ "rootwait" ];
 
@@ -59,12 +57,11 @@ in {
         grub.enable = false;
       };
 
-      kernelPackages = lib.mkDefault pkgs.linuxPackages_librem5;
+      kernelPackages = lib.mkDefault linuxPackages_librem5;
     };
 
-    services.udev.packages = lib.mkIf cfg.installUdevPackages [ pkgs.librem5-base ];
-
-    environment.systemPackages = with pkgs; [ ubootLibrem5 ];
+    services.udev.packages = lib.mkIf cfg.installUdevPackages [ config.hardware.librem5.package ];
 
+    environment.systemPackages = [ ubootLibrem5 ];
   };
 }

purism/librem/5r4/kernel/default.nix

@@ -1,3 +0,0 @@
-final: prev: {
-  linuxPackages_librem5 = final.linuxPackagesFor (final.callPackage ./kernel.nix { });
-}

purism/librem/5r4/lockdown-fix.nix

@@ -11,7 +11,7 @@ lib.mkIf config.hardware.librem5.lockdownFix {
   systemd.services.librem5-lockdown-support = {
     description = "Set up drivers for the orientation and proximity sensors on Librem 5";
     serviceConfig.Type = "oneshot";
-    serviceConfig.ExecStart = "${pkgs.librem5-base}/bin/lockdown-support.sh";
+    serviceConfig.ExecStart = "${config.hardware.librem5.package}/bin/lockdown-support.sh";
     wantedBy = [ "default.target" ];
     path = [ pkgs.kmod ];
   };