add hardware.dts.includes option

NEWS

@@ -134,6 +134,11 @@ and then run the generated `install.sh` script
 
 2024-12-16
 
-config option rename: config.hardware.dts.includes is now
-hardware.dts.includePaths, which is a better name and  also
-means I can use hardware.dts.includes for a different purpose
+Config options changed: if you had set config.hardware.dts.includes
+(maybe in an out-of-tree device port) to specify the search paths
+in which dtc finds include files, you will need to change this to 
+hardware.dts.includePaths.
+
+The "new" hardware.dts.includes option is now for dtsi files which
+should be merged into the device tree.
+

modules/hardware.nix

@@ -29,6 +29,11 @@ in
           description = "List of directories to search for DTS includes (.dtsi files)";
           type = types.listOf types.path;
         };
+        includes = mkOption {
+          default = [ ];
+          description = "\"dtsi\" fragments to include in the generated device tree";
+          type = types.listOf types.path;
+        };
       };
       defaultOutput = mkOption {
         description = "\"Default\" output: what gets built for this device when outputs.default is requested. Typically this is \"mtdimage\" or \"vmroot\"";

modules/outputs.nix

@@ -104,7 +104,7 @@ in
     system.outputs = rec {
       dtb = liminix.builders.dtb {
         inherit (config.boot) commandLine;
-        dts = config.hardware.dts.src;
+        dts = config.hardware.dts.includes ++ [config.hardware.dts.src];
         includes = config.hardware.dts.includePaths ++ [
           "${o.kernel.headers}/include"
         ];

pkgs/kernel/dtb.nix

@@ -2,6 +2,8 @@
   stdenv
 , dtc
 , lib
+, runCommand
+, writeText
 }:
 { dts
 , includes
@@ -10,14 +12,20 @@
   cppDtSearchFlags = builtins.concatStringsSep " " (map (f: "-I${f}") includes);
   dtcSearchFlags = builtins.concatStringsSep " " (map (f: "-i${f}") includes);
   cmdline = lib.concatStringsSep " " commandLine;
+  chosen = writeText "chosen.dtsi" "/{ chosen { bootargs = ${builtins.toJSON cmdline}; }; };";
+  combined = writeText "combined-dts-fragments"
+    (lib.concatStrings
+      (builtins.map
+        (f: "#include \"${f}\"\n")
+        (dts ++ [ chosen ])));
 in stdenv.mkDerivation {
   name = "dtb";
   phases = [ "buildPhase" ];
   nativeBuildInputs = [ dtc ];
   buildPhase = ''
-    ${stdenv.cc.targetPrefix}cpp -nostdinc -x assembler-with-cpp ${cppDtSearchFlags} -undef -D__DTS__  -o dtb.tmp ${dts}
-    echo '/{ chosen { bootargs = ${builtins.toJSON cmdline}; }; };'  >> dtb.tmp
+    ${stdenv.cc.targetPrefix}cpp -nostdinc -x assembler-with-cpp ${cppDtSearchFlags} -undef -D__DTS__  -o dtb.tmp ${combined}
     dtc ${dtcSearchFlags} -I dts  -O dtb -o $out dtb.tmp
+    # dtc -I dtb  -O dts  $out
     test -e $out
   '';
 }