battery charge limit

modules/nixos/hardware/battery/default.nix

@@ -0,0 +1,43 @@
+# echo 81 | sudo tee /sys/class/power_supply/macsmc-battery/charge_control_end_threshold
+{
+  config,
+  pkgs,
+  lib,
+  namespace,
+  ...
+}:
+with lib;
+let
+  inherit (lib.${namespace}) mkOpt;
+  cfg = config.${namespace}.hardware.battery;
+in
+{
+  options.${namespace}.hardware.battery = {
+    enable = mkEnableOption "battery charge limit service";
+
+    chargeLimit = mkOpt types.int 81 "Charge limit for the battery, ex: 81 = 80% charge limit";
+
+    battery = mkOpt types.str "" "Path to the battery charge limit file";
+  };
+
+  config = mkIf cfg.enable {
+    systemd = {
+      services = {
+        set-charge-limit = {
+          enable = true;
+          wantedBy = [ "multi-user.target" ];
+          path = [
+            pkgs.uutils-coreutils-noprefix
+          ];
+          script = ''
+            ${pkgs.uutils-coreutils-noprefix}/bin/echo ${toString cfg.chargeLimit} | tee ${cfg.battery}
+          '';
+          serviceConfig = {
+            Type = "oneshot";
+            TimeoutSec = "5s";
+          };
+        };
+      };
+    };
+  };
+}