diff --git a/rpi/config.nix b/rpi/config.nix
index 1226520..125cb13 100644
--- a/rpi/config.nix
+++ b/rpi/config.nix
@@ -1,126 +1,144 @@
 { lib, config, pkgs, ... }:
 let
   cfg = config.hardware.raspberry-pi;
-  render-raspberrypi-config = let
-    render-options = opts:
-      lib.strings.concatStringsSep "\n" (render-dt-kvs opts);
-    render-dt-param = x: "dtparam=" + x;
-    render-dt-kv = k: v:
-      if isNull v.value then
-        k
-      else
-        let vstr = toString v.value; in "${k}=${vstr}";
-    render-dt-kvs = x:
-      lib.attrsets.mapAttrsToList render-dt-kv
-      (lib.filterAttrs (k: v: v.enable) x);
-    render-dt-overlay = { overlay, args }:
-      "dtoverlay=" + overlay + "\n"
-      + lib.strings.concatMapStringsSep "\n" render-dt-param args + "\n"
-      + "dtoverlay=";
-    render-base-dt-params = params:
-      lib.strings.concatMapStringsSep "\n" render-dt-param
-      (render-dt-kvs params);
-    render-dt-overlays = overlays:
-      lib.strings.concatMapStringsSep "\n" render-dt-overlay
-      (lib.attrsets.mapAttrsToList (k: v: {
-        overlay = k;
-        args = render-dt-kvs v.params;
-      }) (lib.filterAttrs (k: v: v.enable) overlays));
-    render-config-section = k:
-      { options, base-dt-params, dt-overlays }:
-      let
-        all-config = lib.concatStringsSep "\n" (lib.filter (x: x != "") [
-          (render-options options)
-          (render-base-dt-params base-dt-params)
-          (render-dt-overlays dt-overlays)
-        ]);
-      in ''
-        [${k}]
-        ${all-config}
-      '';
-  in conf:
-  lib.strings.concatStringsSep "\n"
-  (lib.attrsets.mapAttrsToList render-config-section conf);
-in {
+  render-raspberrypi-config =
+    let
+      render-options = opts:
+        lib.strings.concatStringsSep "\n" (render-dt-kvs opts);
+      render-dt-param = x: "dtparam=" + x;
+      render-dt-kv = k: v:
+        if isNull v.value then
+          k
+        else
+          let vstr = toString v.value; in "${k}=${vstr}";
+      render-dt-kvs = x:
+        lib.attrsets.mapAttrsToList render-dt-kv
+          (lib.filterAttrs (k: v: v.enable) x);
+      render-dt-overlay = { overlay, args }:
+        "dtoverlay=" + overlay + "\n"
+        + lib.strings.concatMapStringsSep "\n" render-dt-param args + "\n"
+        + "dtoverlay=";
+      render-base-dt-params = params:
+        lib.strings.concatMapStringsSep "\n" render-dt-param
+          (render-dt-kvs params);
+      render-dt-overlays = overlays:
+        lib.strings.concatMapStringsSep "\n" render-dt-overlay
+          (lib.attrsets.mapAttrsToList
+            (k: v: {
+              overlay = k;
+              args = render-dt-kvs v.params;
+            })
+            (lib.filterAttrs (k: v: v.enable) overlays));
+      render-config-section = k:
+        { options, base-dt-params, dt-overlays }:
+        let
+          all-config = lib.concatStringsSep "\n" (lib.filter (x: x != "") [
+            (render-options options)
+            (render-base-dt-params base-dt-params)
+            (render-dt-overlays dt-overlays)
+          ]);
+        in
+        ''
+          [${k}]
+          ${all-config}
+        '';
+    in
+    conf:
+    lib.strings.concatStringsSep "\n"
+      (lib.attrsets.mapAttrsToList render-config-section conf);
+in
+{
   options = {
     hardware.raspberry-pi = {
-      config = let
-        rpi-config-param = {
-          options = {
-            enable = lib.mkEnableOption "attr";
-            value =
-              lib.mkOption { type = with lib.types; oneOf [ int str bool ]; };
-          };
-        };
-        dt-param = {
-          options = {
-            enable = lib.mkEnableOption "attr";
-            value = lib.mkOption {
-              type = with lib.types; nullOr (oneOf [ int str bool ]);
-              default = null;
+      config =
+        let
+          rpi-config-param = {
+            options = {
+              enable = lib.mkEnableOption "attr";
+              value =
+                lib.mkOption { type = with lib.types; oneOf [ int str bool ]; };
             };
           };
-        };
-        dt-overlay = {
-          options = {
-            enable = lib.mkEnableOption "overlay";
-            params = lib.mkOption {
-              type = with lib.types; attrsOf (submodule dt-param);
-            };
-          };
-        };
-        raspberry-pi-config-options = {
-          options = {
-            options = lib.mkOption {
-              type = with lib.types; attrsOf (submodule rpi-config-param);
-              default = { };
-              example = {
-                enable_gic = {
-                  enable = true;
-                  value = true;
-                };
-                arm_boost = {
-                  enable = true;
-                  value = true;
-                };
+          dt-param = {
+            options = {
+              enable = lib.mkEnableOption "attr";
+              value = lib.mkOption {
+                type = with lib.types; nullOr (oneOf [ int str bool ]);
+                default = null;
               };
             };
-            base-dt-params = lib.mkOption {
-              type = with lib.types; attrsOf (submodule rpi-config-param);
-              default = { };
-              example = {
-                i2c = {
-                  enable = true;
-                  value = "on";
-                };
-                audio = {
-                  enable = true;
-                  value = "on";
-                };
+          };
+          dt-overlay = {
+            options = {
+              enable = lib.mkEnableOption "overlay";
+              params = lib.mkOption {
+                type = with lib.types; attrsOf (submodule dt-param);
               };
-              description = "parameters to pass to the base dtb";
-            };
-            dt-overlays = lib.mkOption {
-              type = with lib.types; attrsOf (submodule dt-overlay);
-              default = { };
-              example = { vc4-kms-v3d = { cma-256 = { enable = true; }; }; };
-              description = "dtb overlays to apply";
             };
           };
+          raspberry-pi-config-options = {
+            options = {
+              options = lib.mkOption {
+                type = with lib.types; attrsOf (submodule rpi-config-param);
+                default = { };
+                example = {
+                  enable_gic = {
+                    enable = true;
+                    value = true;
+                  };
+                  arm_boost = {
+                    enable = true;
+                    value = true;
+                  };
+                };
+              };
+              base-dt-params = lib.mkOption {
+                type = with lib.types; attrsOf (submodule rpi-config-param);
+                default = { };
+                example = {
+                  i2c = {
+                    enable = true;
+                    value = "on";
+                  };
+                  audio = {
+                    enable = true;
+                    value = "on";
+                  };
+                };
+                description = "parameters to pass to the base dtb";
+              };
+              dt-overlays = lib.mkOption {
+                type = with lib.types; attrsOf (submodule dt-overlay);
+                default = { };
+                example = { vc4-kms-v3d = { cma-256 = { enable = true; }; }; };
+                description = "dtb overlays to apply";
+              };
+            };
+          };
+        in
+        lib.mkOption {
+          type = with lib.types; attrsOf (submodule raspberry-pi-config-options);
         };
-      in lib.mkOption {
-        type = with lib.types; attrsOf (submodule raspberry-pi-config-options);
+
+      config-generated = lib.mkOption {
+        type = lib.types.str;
+        description = "the config text generated by raspberrypi.hardware.config";
+        readOnly = true;
       };
+
       config-output = lib.mkOption {
         type = lib.types.package;
         default = pkgs.writeTextFile {
           name = "config.txt";
           text = ''
             # This is a generated file. Do not edit!
-            ${render-raspberrypi-config cfg.config}
+            ${cfg.config-generated}
           '';
         };
       };
     };
   };
+  config = {
+    hardware.raspberry-pi.config-generated = render-raspberrypi-config cfg.config;
+  };
 }