nixos/hardware.deviceTree: Move things around

In response to comments, create a sub-folder for deviceTree packages
(starting with rpi), and a top-level package for helpers.

nixos/modules/hardware/device-tree.nix

@@ -19,8 +19,8 @@ in {
         base = mkOption {
           default = "${config.boot.kernelPackages.kernel}/dtbs";
           defaultText = "\${config.boot.kernelPackages.kernel}/dtbs";
-          example = literalExample "pkgs.deviceTree.raspberryPiDtbs";
+          example = literalExample "pkgs.deviceTree_rpi";
-          type = types.nullOr types.path;
+          type = types.path;
           description = ''
             The package containing the base device-tree (.dtb) to boot. Contains
             device trees bundled with the Linux kernel by default.
@@ -30,7 +30,7 @@ in {
         overlays = mkOption {
           default = [];
           example = literalExample
-            "[\"\${pkgs.deviceTree.raspberryPiOverlays}/w1-gpio.dtbo\"]";
+            "[\"\${pkgs.deviceTree_rpi.overlays}/w1-gpio.dtbo\"]";
           type = types.listOf types.path;
           description = ''
             A path containing device tree overlays (.dtbo) to be applied to all
@@ -41,9 +41,9 @@ in {
         package = mkOption {
           default = null;
           type = types.nullOr types.path;
+          internal = true;
           description = ''
-            A path containing device tree overlays (.dtbo) to be applied to all
+            A path containing the result of applying `overlays` to `base`.
-            base device-trees. Overrides `base` and `overlays`.
           '';
         };
       };

pkgs/os-specific/linux/device-tree/default.nix

@@ -1,4 +1,4 @@
-{ stdenvNoCC, dtc, findutils, raspberrypifw }:
+{ stdenvNoCC, dtc, findutils }:
 
 with stdenvNoCC.lib; {
   applyOverlays = (base: overlays: stdenvNoCC.mkDerivation {
@@ -14,15 +14,4 @@ with stdenvNoCC.lib; {
       done
     '';
   });
-
-  raspberryPiDtbs = stdenvNoCC.mkDerivation {
-    name = "raspberrypi-dtbs-${raspberrypifw.version}";
-    nativeBuildInputs = [ raspberrypifw ];
-    buildCommand = ''
-      mkdir -p $out/broadcom/
-      cp ${raspberrypifw}/share/raspberrypi/boot/bcm*.dtb $out/broadcom
-    '';
-  };
-
-  raspberryPiOverlays = "${raspberrypifw}/share/raspberrypi/boot/overlays";
 }

pkgs/os-specific/linux/device-tree/raspberrypi.nix

@@ -0,0 +1,14 @@
+{ stdenvNoCC, raspberrypifw }:
+
+stdenvNoCC.mkDerivation {
+  name = "raspberrypi-dtbs-${raspberrypifw.version}";
+  nativeBuildInputs = [ raspberrypifw ];
+  buildCommand = ''
+    mkdir -p $out/broadcom/
+    cp ${raspberrypifw}/share/raspberrypi/boot/bcm*.dtb $out/broadcom
+  '';
+  passthru = {
+    # Compatible overlays that may be used
+    overlays = "${raspberrypifw}/share/raspberrypi/boot/overlays";
+  };
+}

pkgs/top-level/all-packages.nix

@@ -169,7 +169,9 @@ in
 
   demoit = callPackage ../servers/demoit { };
 
-  deviceTree = callPackage ../os-specific/linux/device-tree.nix {};
+  deviceTree = callPackage ../os-specific/linux/device-tree {};
+
+  device-tree_rpi = callPackage ../os-specific/linux/device-tree/raspberrypi.nix {};
 
   diffPlugins = (callPackage ../build-support/plugins.nix {}).diffPlugins;