rec {
  system = {
    crossSystem = {
      config = "mips-unknown-linux-musl";
      gcc = {
        abi = "32";
        arch = "24kc";          # maybe mips_24kc-
      };
    };
  };

  description = ''
    GL.iNet GL-AR750
    ****************

    The GL-AR750 "Creta" travel router features:

     - QCA9531 @650Mhz SoC
     - dual band wireless: IEEE 802.11a/b/g/n/ac
     - two 10/100Mbps LAN ports and one WAN
     - 128MB DDR2 RAM
     - 16MB NOR Flash
     - supported in OpenWrt by the "ath79" SoC family

    As with many GL.iNet devices, the stock vendor firmware
    is a fork of OpenWrt, meaning that the plain binary
    ``firmware.bin`` that Liminix builds can be flashed using the
    vendor web UI and the U-Boot emergency "unbrick" routine

    The GL-AR750 has two distinct sets of wifi hardware. The 2.4GHz
    radio is part of the QCA9531 SoC, i.e. it's on the same silicon as
    the CPU, the Ethernet, the USB etc. The device is connected to the
    host via AHB, the "Advanced High-Performance Bus" and it is
    supported in Linux using the ath9k driver. The 5GHz support, on the
    other hand, is provided by a QCA9887 PCIe (PCI embedded) WLAN chip:
    I haven't looked closely at the router innards to see if this is
    actually physically a separate board that could be unplugged, but
    as far as Linux is concerned it behaves as one. This is
    supported by the ath10k driver.

    Vendor web page: https://www.gl-inet.com/products/gl-ar750/

    OpenWrt web page: https://openwrt.org/toh/gl.inet/gl-ar750

  '';
  installer = "flashimage";

  module = {pkgs, config, ... }:
    let
      openwrt = pkgs.openwrt;
      firmwareBlobs = pkgs.pkgsBuildBuild.fetchFromGitHub {
        owner = "kvalo";
        repo = "ath10k-firmware";
        rev = "5d63529ffc6e24974bc7c45b28fd1c34573126eb";
        sha256 = "1bwpifrwl5mvsmbmc81k8l22hmkwk05v7xs8dxag7fgv2kd6lv2r";
      };
      firmware = pkgs.stdenv.mkDerivation {
        name = "wlan-firmware";
        phases = ["installPhase"];
        installPhase = ''
          mkdir -p $out/ath10k/QCA9887/hw1.0/
          blobdir=${firmwareBlobs}/QCA9887/hw1.0
          cp $blobdir/10.2.4-1.0/firmware-5.bin_10.2.4-1.0-00047 $out/ath10k/QCA9887/hw1.0/firmware-5.bin
          cp $blobdir/board.bin  $out/ath10k/QCA9887/hw1.0/
        '';
      };
      mac80211 = pkgs.mac80211.override {
        drivers = ["ath9k" "ath10k_pci"];
        klibBuild = config.system.outputs.kernel.modulesupport;
      };
      ath10k_cal_data =
        let
          offset = 1024 * 20; # 0x5000
          size = 2048 + 68; # 0x844
        in pkgs.liminix.services.oneshot rec  {
          name = "ath10k_cal_data";
          up = ''
            part=$(basename $(dirname $(grep -l art /sys/class/mtd/*/name)))
            echo ART partition is ''${part-unset}
            test -n "$part" || exit 1
            (in_outputs ${name}
             dd if=/dev/$part of=data iflag=skip_bytes,fullblock bs=${toString size} skip=${toString offset} count=1
            )
        '';
      };
      inherit (pkgs.pseudofile) dir symlink;
      inherit (pkgs.liminix.networking) interface;
    in {
      imports = [
        ../../modules/network
        ../../modules/arch/mipseb.nix
      ];

      programs.busybox.options = {
        FEATURE_DD_IBS_OBS = "y"; # ath10k_cal_data needs skip_bytes,fullblock
      };
      hardware = {
        defaultOutput = installer;
        loadAddress = "0x80060000";
        entryPoint  = "0x80060000";
        flash = {
          address = "0x9F060000";
          size ="0xfa0000";
          eraseBlockSize = "65536";
        };
        rootDevice = "/dev/mtdblock5";
        dts = {
          src = "${openwrt.src}/target/linux/ath79/dts/qca9531_glinet_gl-ar750.dts";
          includes =  [
            "${openwrt.src}/target/linux/ath79/dts"
          ];
        };

        networkInterfaces =
          let inherit (config.system.service.network) link;
          in {
            lan = link.build { ifname = "eth0"; };
            wan = link.build { ifname = "eth1"; };
            wlan = link.build {
              ifname = "wlan0";
              dependencies = [ mac80211 ];
            };
            wlan5 = link.build {
              ifname = "wlan1";
              dependencies = [ mac80211 ath10k_cal_data ];
            };
          };
      };
      filesystem = dir {
        lib = dir {
          firmware = dir {
            ath10k = dir {
              QCA9887 = symlink "${firmware}/ath10k/QCA9887";
              "cal-pci-0000:00:00.0.bin" = symlink "${ath10k_cal_data}/.outputs/data";
            };
          };
        };
      };
      boot.tftp = {
        loadAddress = "0x00A00000";
      };
      kernel = {
        src = pkgs.pkgsBuildBuild.fetchurl {
          name = "linux.tar.gz";
          url = "https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.15.71.tar.gz";
          hash = "sha256-yhO2cXIeIgUxkSZf/4aAsF11uxyh+UUZu6D1h92vCD8=";
        };
        extraPatchPhase = ''
          ${openwrt.applyPatches.ath79}
        '';
        config = {
          ATH79 = "y";
          PCI = "y";
          PCI_AR724X = "y";

          SERIAL_8250_CONSOLE = "y";
          SERIAL_8250 = "y";
          SERIAL_CORE_CONSOLE = "y";

          # need this to open console device at boot. dmesg goes from
          # [    0.272934] Warning: unable to open an initial console.
          # to
          # [    0.247413] printk: console [ttyS0] disabled
          # [     0.25200] 18020000.uart: ttyS0 at MMIO 0x1802000 (irq = 10, base_baud = 1562500) is a 16550A
          SERIAL_OF_PLATFORM = "y";

          CONSOLE_LOGLEVEL_DEFAULT = "8";
          CONSOLE_LOGLEVEL_QUIET = "4";

          NET = "y";
          ETHERNET = "y";
          NET_VENDOR_ATHEROS = "y";
          AG71XX = "y";             # ethernet (qca,qca9530-eth)
          MFD_SYSCON = "y";         # ethernet (compatible "syscon")
          AR8216_PHY = "y";         # eth1 is behind a switch

          MTD_SPI_NOR = "y";

          SPI_ATH79 = "y";      # these are copied from OpenWrt.
          SPI_MASTER= "y";      # At least one of them is necessary
          SPI_MEM= "y";
          SPI_AR934X= "y";
          SPI_BITBANG= "y";
          SPI_GPIO= "y";

          GPIO_ATH79 = "y";
          GPIOLIB = "y";
          EXPERT="y";
          GPIO_SYSFS = "y"; # required by patches-5.15/0004-phy-add-ath79-usb-phys.patch
          OF_GPIO = "y";
          SYSFS = "y";
          SPI = "y";
          MTD = "y";
          MTD_BLOCK = "y";          # fix undefined ref to register_mtd_blktrans_devs

          WATCHDOG = "y";
          ATH79_WDT = "y";  # watchdog timer

          # this is all copied from nixwrt ath79 config. Clearly not all
          # of it is device config, some of it is wifi config or
          # installation method config or ...

          EARLY_PRINTK = "y";

          PRINTK_TIME = "y";
        };
      };
    };
}