uboot: (firmwareOdroidC2/C4) don't invoke patch tool, use patches = [] instead

https://github.com/NixOS/nixpkgs/blob/master/pkgs/stdenv/generic/setup.sh#L948
this can do it nicely.

Signed-off-by: Anton Arapov <anton@deadbeef.mx>

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

@@ -0,0 +1,32 @@
+{ lib, stdenvNoCC, dtc }:
+
+with lib; {
+  applyOverlays = (base: overlays': stdenvNoCC.mkDerivation {
+    name = "device-tree-overlays";
+    nativeBuildInputs = [ dtc ];
+    buildCommand = let
+      overlays = toList overlays';
+    in ''
+      mkdir -p $out
+      cd ${base}
+      find . -type f -name '*.dtb' -print0 \
+        | xargs -0 cp -v --no-preserve=mode --target-directory $out --parents
+
+      for dtb in $(find $out -type f -name '*.dtb'); do
+        dtbCompat="$( fdtget -t s $dtb / compatible )"
+
+        ${flip (concatMapStringsSep "\n") overlays (o: ''
+        overlayCompat="$( fdtget -t s ${o.dtboFile} / compatible )"
+        # overlayCompat in dtbCompat
+        if [[ "$dtbCompat" =~ "$overlayCompat" ]]; then
+          echo "Applying overlay ${o.name} to $( basename $dtb )"
+          mv $dtb{,.in}
+          fdtoverlay -o "$dtb" -i "$dtb.in" ${o.dtboFile};
+          rm $dtb.in
+        fi
+        '')}
+
+      done
+    '';
+  });
+}

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

@@ -0,0 +1,38 @@
+{ lib, stdenvNoCC, raspberrypifw }:
+
+stdenvNoCC.mkDerivation {
+  pname = "raspberrypi-dtbs";
+  version = raspberrypifw.version;
+  nativeBuildInputs = [ raspberrypifw ];
+
+  # Rename DTBs so u-boot finds them, like linux-rpi.nix
+  buildCommand = ''
+    mkdir -p $out/broadcom/
+    cd $out/broadcom/
+
+    cp ${raspberrypifw}/share/raspberrypi/boot/bcm*.dtb .
+
+    cp bcm2708-rpi-zero-w.dtb bcm2835-rpi-zero-w.dtb
+    cp bcm2708-rpi-b.dtb bcm2835-rpi-a.dtb
+    cp bcm2708-rpi-b.dtb bcm2835-rpi-b.dtb
+    cp bcm2708-rpi-b.dtb bcm2835-rpi-b-rev2.dtb
+    cp bcm2708-rpi-b-plus.dtb bcm2835-rpi-a-plus
+    cp bcm2708-rpi-b-plus.dtb bcm2835-rpi-b-plus
+    cp bcm2708-rpi-b-plus.dtb bcm2835-rpi-zero.dtb
+    cp bcm2708-rpi-cm.dtb bcm2835-rpi-cm.dtb
+    cp bcm2709-rpi-2-b.dtb bcm2836-rpi-2-b.dtb
+    cp bcm2710-rpi-3-b.dtb bcm2837-rpi-3-b.dtb
+    cp bcm2710-rpi-3-b-plus.dtb bcm2837-rpi-3-b-plus.dtb
+    cp bcm2710-rpi-cm3.dtb bcm2837-rpi-cm3.dtb
+    cp bcm2711-rpi-4-b.dtb bcm2838-rpi-4-b.dtb
+  '';
+
+  passthru = {
+    # Compatible overlays that may be used
+    overlays = "${raspberrypifw}/share/raspberrypi/boot/overlays";
+  };
+  meta = with lib; {
+    inherit (raspberrypifw.meta) homepage license;
+    description = "DTBs for the Raspberry Pi";
+  };
+}