coreboot: rewrite the toConf function

- Use builtins.toJSON
- Fix nested attriute sets

coreboot.nix

@@ -1,4 +1,4 @@
-{ stdenv, fetchurl, fetchgit
+{ lib, stdenv, fetchurl, fetchgit
 , linkFarm, overrideCC
 , writeText, writeShellScriptBin
 , gnat, bison, flex, zlib, python3
@@ -11,7 +11,6 @@
 }:
 
 let
-  lib = stdenv.lib;
   adaStdenv = overrideCC stdenv gnat;
   version = lib.substring 0 6 rev;
 
@@ -29,7 +28,7 @@ in rec {
   # seabios source
   seabios = builtins.fetchGit {
     url = "https://review.coreboot.org/seabios.git";
-    rev = conf.seabios.revision_id;
+    rev = conf.seabios.revision-id;
   };
 
   # tarballs needed to build the toolchain
@@ -41,25 +40,23 @@ in rec {
   ## Helpers
 
   # converts Nix attrs to Kconfig format
-  toConf = top: n: v: with builtins;
+  toConf = prefix: name: val:
     let
-      prefix = lib.optionalString top "CONFIG_";
-      nconv = n: replaceStrings ["-"] ["_"] (lib.toUpper n);
-      vconv = v: if isBool v then (if v then "y" else "n")
-            else if (isString v) || (isPath v) || (lib.isDerivation v) then "\"${v}\""
-            else toString v;
+      name' = lib.replaceStrings ["-"] ["_"] (lib.toUpper name);
+      val' = if lib.isBool val then (if val then "y" else "n")
+             else builtins.toJSON val;
+      sub = "${prefix}_${name'}";
     in
-      if (lib.isAttrs v && ! lib.isDerivation v)
-      then (lib.concatMapStringsSep "\n"
-             (line: "${prefix}${nconv n}_${line}")
-             (lib.mapAttrsToList (toConf false) v))
-      else "${prefix}${nconv n}=${vconv v}";
+      if lib.isAttrs val && ! lib.isDerivation val
+      then (lib.concatStringsSep "\n"
+             (lib.mapAttrsToList (toConf sub) val))
+      else "${prefix}_${name'}=${val'}";
 
   # the coreboot Kconfig file
   defConfig = with lib;
     writeText "defconfig"
       (concatStringsSep "\n"
-        (mapAttrsToList (toConf true) conf));
+        (mapAttrsToList (toConf "CONFIG") conf));
 
   # returns the current revision
   fakegit = writeShellScriptBin "git" "echo ${version}";
@@ -141,7 +138,7 @@ in rec {
       make savedefconfig DEFCONFIG=$out/defconfig
     '';
 
-    meta = with stdenv.lib; {
+    meta = {
       description = "Fast, secure and flexible OpenSource firmware";
       longDescription = ''
         coreboot is an extended firmware platform that delivers a lightning
@@ -150,8 +147,8 @@ in rec {
         control over technology.
       '';
       homepage  = "https://www.coreboot.org";
-      license   = licenses.gpl2Only;
-      platforms = platforms.all;
+      license   = lib.licenses.gpl2Only;
+      platforms = lib.platforms.all;
     };
 
   };