feat(uConsole): add disko, backlight fix, GPIO 23, mt7921u

- Add disko flake input + partition config (/boot/firmware, /, /home)
- Add cm5-backlight-fix service as display fallback
- Add enable-gpio23-usb-hub service for internal USB hub
- Add mt7921u kernel module for MediaTek AC1200 WiFi
- Add gpiod package for GPIO userspace control

flake.nix

@@ -8,6 +8,10 @@
       inputs.darwin.follows = "";
       inputs.nixpkgs.follows = "nixpkgs";
     };
+    disko = {
+      url = "github:nix-community/disko";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
     lix = {
       url = "git+https://git.lix.systems/lix-project/lix?ref=main";
       inputs.nixpkgs.follows = "nixpkgs";
@@ -23,7 +27,7 @@
     self.submodules = true;
   };
 
-  outputs = { self, nixpkgs, agenix, lix, nixos-uconsole, nixos-raspberrypi, ... }@inputs:
+  outputs = { self, nixpkgs, agenix, disko, lix, nixos-uconsole, nixos-raspberrypi, ... }@inputs:
     let
       system = "x86_64-linux";
       keys = import ./lib/keys.nix;
@@ -100,8 +104,10 @@
               }
               nixos-raspberrypi.nixosModules.raspberry-pi-5.base
               nixos-uconsole.nixosModules.uconsole-cm5
+              disko.nixosModules.disko
               ./hosts/uConsole/configuration.nix
               ./hosts/uConsole/hardware-configuration.nix
+              ./hosts/uConsole/disko-config.nix
             ];
           };
         };

hosts/uConsole/configuration.nix

@@ -1,5 +1,19 @@
 { config, lib, pkgs, paths, self, keys, ... }:
 
+let
+  # Backlight fallback for CM5 display quirk
+  # The kernel driver usually handles this, but some boots need a kick
+  backlightFixScript = pkgs.writeShellScript "backlight-fix" ''
+    # Try sysfs backlight control
+    for bl in /sys/class/backlight/*/brightness; do
+      if [ -f "$bl" ]; then
+        max=$(cat "$(dirname "$bl")/max_brightness" 2>/dev/null || echo 100)
+        echo "$max" > "$bl" 2>/dev/null || true
+      fi
+    done
+  '';
+in
+
 {
   # Basic Host Info
   networking.hostName = "uConsole";
@@ -56,6 +70,7 @@
     htop
     tmux
     neovim
+    gpiod                       # GPIO control (for internal USB hub, AIO modules)
 
     # ===== HAM Radio =====
     js8call
@@ -139,9 +154,10 @@
   };
 
   # ============================================================
-  # Kernel modules for SDR and radio
+  # Kernel modules for SDR, radio, and WiFi
   # ============================================================
   boot.kernelModules = [
+    "mt7921u"         # MediaTek MT7921 USB WiFi (uConsole AC1200)
     "88x2bu"          # Realtek 8812/8821BU USB WiFi (common adapter)
     "rtl8xxxu"        # RTL8188/8192/8723 USB WiFi
     "rtl2832_sdr"     # RTL-SDR kernel module
@@ -168,4 +184,37 @@
   # Reticulum uses its own encryption and doesn't need open ports
   # for basic mesh operations (peer-to-peer discovery).
   # For TCP interfaces, open additional ports as needed.
+
+  # ============================================================
+  # CM5 Display Backlight Fix
+  # The kernel driver initializes backlight, but some boots fail.
+  # This service kicks it after boot as a reliable fallback.
+  # ============================================================
+  systemd.services.cm5-backlight-fix = {
+    description = "CM5 Display Backlight Fix";
+    after = [ "multi-user.target" ];
+    wantedBy = [ "multi-user.target" ];
+    serviceConfig = {
+      Type = "oneshot";
+      ExecStart = "${backlightFixScript}";
+    };
+  };
+
+  # ============================================================
+  # Internal USB Hub Enable (GPIO 23)
+  # The Hacker Gadgets AIO V2 board has an internal USB hub for
+  # the AC1200 WiFi, SDR, and other peripherals. GPIO 23 must be
+  # HIGH to power the hub. CM5 defaults GPIO 23 to LOW.
+  # ============================================================
+  systemd.services.enable-gpio23-usb-hub = {
+    description = "Enable Internal USB Hub (GPIO 23)";
+    before = [ "network.target" ];
+    wantedBy = [ "multi-user.target" ];
+    serviceConfig = {
+      Type = "oneshot";
+      RemainAfterExit = true;
+      ExecStart = "${pkgs.gpiod}/bin/gpioset 0 23=1";
+      ExecStop = "${pkgs.gpiod}/bin/gpioset 0 23=0";
+    };
+  };
 }

hosts/uConsole/disko-config.nix

@@ -0,0 +1,48 @@
+{ lib, ... }:
+{
+  disk = {
+    main = {
+      type = "disk";
+      device = "/dev/disk/by-path/platform-fe340000.mmc";
+      content = {
+        type = "gpt";
+        partitions = {
+          boot = {
+            name = "FIRMWARE";
+            size = "1G";
+            type = "EF00";
+            content = {
+              type = "filesystem";
+              format = "vfat";
+              mountpoint = "/boot/firmware";
+              mountOptions = [
+                "fmask=0022"
+                "dmask=0022"
+              ];
+            };
+          };
+          root = {
+            name = "NIXOS_UCM5";
+            size = "30G";
+            content = {
+              type = "filesystem";
+              format = "ext4";
+              mountpoint = "/";
+              mountOptions = [ "noatime" ];
+            };
+          };
+          home = {
+            name = "NIXOS_HOME";
+            size = "100%";
+            content = {
+              type = "filesystem";
+              format = "ext4";
+              mountpoint = "/home";
+              mountOptions = [ "noatime" ];
+            };
+          };
+        };
+      };
+    };
+  };
+}

hosts/uConsole/hardware-configuration.nix

@@ -9,15 +9,26 @@
   boot.initrd.kernelModules = [ ];
   boot.extraModulePackages = [ ];
 
-  # uConsole CM5 uses NVMe or eMMC for boot storage
-  # The uconsole-cm5 module sets up /boot/firmware and default /
-  # Override device label here if using different storage
-  fileSystems."/" = lib.mkDefault {
+  # uConsole CM5 eMMC partitions managed by disko
+  # Labels defined in disko-config.nix
+  fileSystems."/" = {
     device = "/dev/disk/by-label/NIXOS_UCM5";
     fsType = "ext4";
     options = [ "noatime" ];
   };
 
+  fileSystems."/boot/firmware" = {
+    device = "/dev/disk/by-label/FIRMWARE";
+    fsType = "vfat";
+    options = lib.mkForce [ "fmask=0022" "dmask=0022" ];
+  };
+
+  fileSystems."/home" = {
+    device = "/dev/disk/by-label/NIXOS_HOME";
+    fsType = "ext4";
+    options = [ "noatime" ];
+  };
+
   swapDevices = [ ];
 
   nixpkgs.hostPlatform = lib.mkDefault "aarch64-linux";