nix: basic packaging

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: I6a6a6964c848d4871ead297560a06c2e1dd2f14d

flake.lock

@@ -0,0 +1,27 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1759381078,
+        "narHash": "sha256-gTrEEp5gEspIcCOx9PD8kMaF1iEmfBcTbO0Jag2QhQs=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "7df7ff7d8e00218376575f0acdcc5d66741351ee",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,96 @@
+{
+  inputs.nixpkgs.url = "github:nixos/nixpkgs?ref=nixos-unstable";
+
+  outputs = {
+    self,
+    nixpkgs,
+  }: let
+    system = "x86_64-linux";
+    pkgs = nixpkgs.legacyPackages.${system};
+    lib = nixpkgs.lib;
+  in {
+    packages."${system}" = let
+      inherit (pkgs.linuxPackages_latest) kernel;
+      kmod = pkgs.callPackage ./nix/kmod.nix {inherit kernel;};
+    in {
+      inherit kernel kmod;
+    };
+
+    nixosConfigurations."gamma" = let
+      inherit (lib) nixosSystem;
+      inherit (lib.modules) mkDefault;
+    in
+      nixosSystem {
+        system = null;
+        modules = [
+          ({modulesPath, ...}: {
+            imports = [(modulesPath + "/profiles/qemu-guest.nix")];
+            networking.hostName = "gamma";
+
+            boot = {
+              growPartition = false;
+              kernelParams = ["console=ttyAMA0,115200n8" "console=tty0"];
+              consoleLogLevel = mkDefault 7; # ground control to kernel
+            };
+
+            # Empty password
+            # root can login without a password
+            users.extraUsers.root.initialHashedPassword = "";
+
+            # Nixpkgs options
+            nixpkgs.pkgs = pkgs; # discard everything else, follow flake `pkgs`
+
+            # Packages
+            environment.systemPackages = [pkgs.microfetch];
+
+            # Bootable
+            fileSystems."/boot" = {
+              device = "/dev/vda1";
+              fsType = "vfat";
+            };
+
+            fileSystems."/" = {
+              device = "/dev/vda2";
+              fsType = "ext4";
+            };
+
+            boot.loader.grub = {
+              efiSupport = true;
+              efiInstallAsRemovable = true;
+              device = "nodev";
+            };
+
+            # Kernel fun
+            boot = {
+              # Use kernel package defined in flake.nix
+              kernelPackages = pkgs.linuxPackagesFor self.packages.${system}.kernel; # exposed kernel
+
+              # Get test module from flake outputs
+              extraModulePackages = [self.packages.${system}.kmod];
+
+              # Load module from package.
+              # Alternatively, `$ modprobe test` would work too
+              kernelModules = ["deepcool"];
+            };
+
+            # Make it smaller
+            documentation = {
+              doc.enable = false;
+              man.enable = false;
+              nixos.enable = false;
+              info.enable = false;
+            };
+
+            # Get out.
+            programs = {
+              bash.completion.enable = false;
+              command-not-found.enable = false;
+            };
+
+            # Shut up.
+            system.stateVersion = "25.11";
+          })
+        ];
+      };
+  };
+}

nix/kmod.nix

@@ -0,0 +1,76 @@
+{
+  lib,
+  stdenv,
+  linuxPackages_latest,
+  kernel ? linuxPackages_latest.kernel,
+  ...
+}: let
+  pname = "deepcool";
+  version = "0.1.0";
+in
+  stdenv.mkDerivation {
+    inherit pname version;
+
+    src = let
+      fs = lib.fileset;
+      sp = ../.;
+    in
+      fs.toSource {
+        root = sp;
+        fileset = fs.unions [
+          (sp + /deepcool.c)
+          (sp + /Makefile)
+        ];
+      };
+
+    enableParallelBuilding = true;
+    nativeBuildInputs = kernel.moduleBuildDependencies;
+    hardeningDisable = ["pic" "format"];
+
+    env = {
+      KVERSION = kernel.modDirVersion;
+      INSTALL_MOD_PATH = builtins.placeholder "out";
+    };
+
+    buildPhase = ''
+      runHook preBuild
+      echo "Kernel version: $KVERSION"
+      make -C ${kernel.dev}/lib/modules/${kernel.modDirVersion}/build \
+        M=$(pwd) \
+        modules
+      runHook postBuild
+    '';
+
+    installPhase = ''
+      runHook preInstall
+      echo "Module Installation Path: $INSTALL_MOD_PATH"
+      make -C ${kernel.dev}/lib/modules/${kernel.modDirVersion}/build \
+        M=$(pwd) \
+        modules_install
+      runHook postInstall
+    '';
+
+    postInstall = ''
+      if [ -d $out/lib/modules/${kernel.modDirVersion}/extra ]; then
+        mkdir -p $out/lib/modules/${kernel.modDirVersion}/kernel/drivers/hid
+        find $out/lib/modules/${kernel.modDirVersion}/extra -name "*.ko*" \
+          -exec mv {} $out/lib/modules/${kernel.modDirVersion}/kernel/drivers/hid/ \;
+        rmdir $out/lib/modules/${kernel.modDirVersion}/extra 2>/dev/null || true
+      fi
+    '';
+
+    passthru = {
+      inherit kernel;
+      kernelVersion = kernel.modDirVersion;
+      moduleName = "deepcool_digital";
+      modulePath = "kernel/drivers/hid/deepcool_digital.ko";
+    };
+
+    meta = {
+      description = "Linux kernel module for Deepcool Digital USB HID devices";
+      license = lib.licenses.gpl2Plus;
+      maintainers = [];
+      platforms = lib.platforms.linux;
+      broken = lib.versionOlder kernel.version "5.10";
+    };
+  }