add hardware.dts.includes option

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"
         ];