gl-ar750: update to newer kernel + openwrt

this device is not (yet?) in mainline, but openwrt 25.12 has
the right patches to make it work with linux 6.12

devices/gl-ar750/default.nix

@@ -60,7 +60,7 @@
     }:
     let
       inherit (lib) mkIf;
-      openwrt = pkgs.openwrt;
+      openwrt = pkgs.openwrt_25_12;
       firmwareBlobs = pkgs.pkgsBuildBuild.fetchgit {
         url = "https://git.codelinaro.org/clo/ath-firmware/ath10k-firmware";
         rev = "5d63529ffc6e24974bc7c45b28fd1c34573126eb";
@@ -175,13 +175,14 @@
         appendDTB = true;
       };
       kernel = {
-        # Mainline linux 5.19 doesn't have device-tree support for
+        # Mainline linux 6.12 doesn't have device-tree support for
         # this device or even for the SoC, so we use the extensive
         # OpenWrt kernel patches
+        src = openwrt.kernelSrc;
+        version = openwrt.kernelVersion;
         extraPatchPhase = ''
           ${openwrt.applyPatches.ath79}
           sed -i.bak -e '\,include <linux/hw_random.h>,a #include <linux/gpio/driver.h>'  drivers/net/wireless/ath/ath9k/ath9k.h # context reqd for next patch
-          patch -p1 <  ${openwrt.src}/package/kernel/mac80211/patches/ath9k/552-ath9k-ahb_of.patch
         '';
 
         config = {

pkgs/default.nix

@@ -135,6 +135,7 @@ in
   odhcp6c = callPackage ./odhcp6c { };
   openwrt = callPackage ./openwrt { };
   openwrt_24_10 = callPackage ./openwrt/2410.nix { };
+  openwrt_25_12 = callPackage ./openwrt/2512.nix { };
   output-template = callPackage ./output-template { };
   ppp = callPackage ./ppp { };
   pppoe = callPackage ./pppoe { };

pkgs/openwrt/2512.nix

@@ -0,0 +1,105 @@
+{
+  fetchFromGitHub,
+  pkgsBuildBuild,
+  lib,
+  cpio
+}:
+let
+  src = fetchFromGitHub {
+    name = "openwrt-source";
+    repo = "openwrt";
+    owner = "openwrt";
+    rev = "v25.12.1";
+    hash = "sha256-RshgHcH5d1pmS00XPj1DAmfApT4xXrC+QI4Vg2rd/dE=";
+  };
+  # we don't use different kernel versions for monolith and mac80211 as
+  # openwrt does, so we also need an older openwrt version with
+  # the wireless patches that correspond to 6.12.x
+  oldSrc = fetchFromGitHub {
+    name = "openwrt-source";
+    repo = "openwrt";
+    owner = "openwrt";
+    rev = "c8eacec725dce34c7b621f00c9bce814fe413759";
+    hash = "sha256-YTfAWmFPXPXFQ56QGRLgCc/QY+RndOdVdcgtBaZsh1E=";
+  };
+  kernelVersion = "6.12.77";
+  kernelSeries = lib.versions.majorMinor kernelVersion;
+  doPatch = family: ''
+    tar -C ${src}/target/linux/generic/files -cf - . | tar xpf -
+    chmod -R u+w .
+    tar -C ${src}/target/linux/${family}/files -cf - . | tar xpf -
+    chmod -R u+w .
+    test -d ${src}/target/linux/${family}/files-${kernelSeries}/ && ( tar -C ${src}/target/linux/${family}/files-${kernelSeries} -cf - . | tar xpf -)
+    chmod -R u+w .
+
+    ensure_patch() {
+      echo Applying $1
+      # skip patches which are already applied by testing if they
+      # can be dry-run in reverse
+      patch --batch --forward -p1 < $1 ||
+        patch --batch --reverse --dry-run -p1 < $1
+
+    }
+    patches() {
+      for i in $* ; do
+         ensure_patch $i
+      done
+    }
+
+    patches ${src}/target/linux/generic/backport-${kernelSeries}/*.patch
+    patches ${src}/target/linux/generic/pending-${kernelSeries}/*.patch
+    patches ${src}/target/linux/generic/hack-${kernelSeries}/*.patch
+    patches ${src}/target/linux/${family}/patches-${kernelSeries}/*.patch
+
+    for kconfig in $(find drivers/net/wireless/ -name Kconfig); do
+      sed -i.bak -E -e '/^((\s+))tristate/a\
+\tdepends on m'  $kconfig
+    done
+
+    mkdir backport_patches
+    for f in ${oldSrc}/package/kernel/mac80211/patches/*.*; do
+      out=backport_patches/`basename $f`
+      sed < $f 's/CPTCFG_/CONFIG_/g' > $out
+      ensure_patch $out
+    done
+  '';
+in
+{
+  inherit src;
+
+  # The kernel sources typically used with this version of openwrt
+  # You can find this in `include/kernel-5.15` or similar in the
+  # openwrt sources
+  kernelSrc = pkgsBuildBuild.fetchurl {
+    name = "linux.tar.gz";
+    url = "https://cdn.kernel.org/pub/linux/kernel/v${lib.versions.major kernelVersion}.x/linux-${kernelVersion}.tar.gz";
+    hash = "sha256-kPvUXXvWWmZ+B3ONP7iC2zlwaBom/RCNw6oxXeb47zU=";
+  };
+  inherit kernelVersion;
+
+  applyPatches.ath79 = doPatch "ath79";
+  applyPatches.ramips = doPatch "ramips";
+  applyPatches.mediatek = doPatch "mediatek"; # aarch64
+  applyPatches.mvebu = doPatch "mvebu"; # arm
+
+  applyPatches.rt2x00 = ''
+    PATH=${pkgsBuildBuild.patchutils}/bin:$PATH
+    for i in ${src}/package/kernel/mac80211/patches/rt2x00/6*.patch ; do
+      fixed=$(basename $i).fixed
+      sed '/depends on m/d'  < $i | sed 's/CPTCFG_/CONFIG_/g' | recountdiff | filterdiff -x '*/local-symbols' > $fixed
+      case $fixed in
+        606-*)
+          ;;
+        611-*)
+          filterdiff -x '*/rt2x00.h' < $fixed | patch --forward -p1
+          ;;
+        601-*|607-*)
+          filterdiff -x '*/rt2x00_platform.h' < $fixed | patch --forward -p1
+          ;;
+        *)
+          cat $fixed | patch --forward -p1
+          ;;
+      esac
+    done
+  '';
+}