From 51ed79611de509927bd6e74dd9792e287e3c5dc2 Mon Sep 17 00:00:00 2001
From: Lumpiasty <arek.dzski@gmail.com>
Date: Fri, 1 Aug 2025 21:57:35 +0200
Subject: [PATCH] add acer-wmi-battery kernel driver

---
 hosts/acer.nix                    | 11 ++++++-
 overlays/pkgs.nix                 |  3 ++
 pkgs/acer-wmi-battery/default.nix | 48 +++++++++++++++++++++++++++++++
 3 files changed, 61 insertions(+), 1 deletion(-)
 create mode 100644 pkgs/acer-wmi-battery/default.nix

diff --git a/hosts/acer.nix b/hosts/acer.nix
index 011ef03..a6d31f3 100644
--- a/hosts/acer.nix
+++ b/hosts/acer.nix
@@ -1,6 +1,6 @@
 { lib, pkgs, ... }:
 
-{
+rec {
   # Identity
   networking.hostName = "acer"; # Define your hostname.
   networking.hostId = "fc9583ce";
@@ -90,6 +90,15 @@
   # For dev vm stuff
   networking.firewall.trustedInterfaces = [ "br0" ];
 
+  # Battery driver
+  boot.extraModulePackages = [
+    # Super ugly hack, for some reason it's not included in pkgs.linuxKernel.packages.linux_6_12
+    # Despite being in overlays, something's not working
+    (pkgs.linuxPackages.acer-wmi-battery.override {
+      kernel = boot.kernelPackages.kernel;
+    })
+  ];
+
   # This value determines the NixOS release from which the default
   # settings for stateful data, like file locations and database versions
   # on your system were taken. It‘s perfectly fine and recommended to leave
diff --git a/overlays/pkgs.nix b/overlays/pkgs.nix
index 917d919..b3152b1 100644
--- a/overlays/pkgs.nix
+++ b/overlays/pkgs.nix
@@ -11,4 +11,7 @@ self: super:
   #     version = "6.3.1";
   #   });
   # });
+  linuxPackages = super.linuxPackages.extend (lpself: lpsuper: {
+    acer-wmi-battery = lpsuper.callPackage ../pkgs/acer-wmi-battery {};
+  });
 }
\ No newline at end of file
diff --git a/pkgs/acer-wmi-battery/default.nix b/pkgs/acer-wmi-battery/default.nix
new file mode 100644
index 0000000..8252b40
--- /dev/null
+++ b/pkgs/acer-wmi-battery/default.nix
@@ -0,0 +1,48 @@
+# Custom module for Acer WMI features, like battery charge limit
+{
+  lib,
+  stdenv,
+  fetchFromGitHub,
+  kernel
+}:
+
+stdenv.mkDerivation {
+  pname = "acer-wmi-battery";
+  version = "0.0.0";
+
+  src = fetchFromGitHub {
+    owner = "frederik-h";
+    repo = "acer-wmi-battery";
+    rev = "0889d3ea54655eaa88de552b334911ce7375952f";
+    sha256 = "sha256-mI6Ob9BmNfwqT3nndWf3jkz8f7tV10odkTnfApsNo+A=";
+  };
+
+  nativeBuildInputs = [ kernel.moduleBuildDependencies ];
+
+  makeFlags = kernel.makeFlags ++ [
+    "INSTALL_MOD_PATH=$(out)"
+  ];
+
+  # Makefile provided in repo is useless, hardcoded paths, overwriting it
+  patchPhase = ''
+    cat > Makefile <<EOF
+    obj-m += acer-wmi-battery.o
+
+    all:
+    $(printf '\t')make -C ${kernel.dev}/lib/modules/${kernel.modDirVersion}/build M=\$(PWD) modules
+
+    modules_install:
+    $(printf '\t')make -C ${kernel.dev}/lib/modules/${kernel.modDirVersion}/build M=\$(PWD) modules_install
+    EOF
+  '';
+
+  buildFlags = [ "all" ];
+  installTargets = [ "modules_install" ];
+
+  meta = {
+    description = "Acer WMI kernel module for battery charge limit";
+    homepage = "https://github.com/frederik-h/acer-wmi-battery";
+    license = lib.licenses.gpl2;
+    platforms = lib.platforms.linux;
+  };
+}