Rework laptop battery/power optimization settings

system/roles/laptop/power/auto-cpufreq/default.nix

@@ -0,0 +1,47 @@
+# This sets up power management using auto-cpufreq,
+# alongside with upower and power-profiles-daemon.
+# Together, this provides a complete alternative to TLP
+{ pkgs, lib, config, ...}: let
+  inherit (lib) mkIf mkDefault;
+  deviceType = config.myOptions.device.roles.type;
+  acceptedTypes = ["laptop"];
+in {
+  imports = [
+    ./power-profiles-daemon
+  ];
+
+  config = mkIf (builtins.elem deviceType acceptedTypes) {
+    services = {
+      # superior power management
+      auto-cpufreq = {
+        enable = true;
+        settings = let
+          MHz = x: x * 1000;
+        in {
+          battery = {
+            governor = "powersave";
+            scaling_min_freq = mkDefault (MHz 1200);
+            scaling_max_freq = mkDefault (MHz 1800);
+            turbo = "never";
+          };
+
+          charger = {
+            governor = "performance";
+            scaling_min_freq = mkDefault (MHz 1800);
+            scaling_max_freq = mkDefault (MHz 3800);
+            turbo = "auto";
+          };
+        };
+      };
+
+      # DBus service that provides power management support to applications
+      upower = {
+        enable = true;
+        percentageLow = 15;
+        percentageCritical = 5;
+        percentageAction = 3;
+        criticalPowerAction = "Hibernate";
+      };
+    };
+  };
+}

system/roles/laptop/power/auto-cpufreq/power-profiles-daemon/default.nix

@@ -0,0 +1,40 @@
+# This sets up power management using auto-cpufreq,
+# alongside with upower and power-profiles-daemon.
+# Together, this provides a complete alternative to TLP
+{ pkgs, lib, config, ...}: let
+  inherit (lib) mkIf;
+  inherit (lib.modules) mkForce;
+  inherit (lib.strings) makeBinPath;
+  deviceType = config.myOptions.device.roles.type;
+  acceptedTypes = ["laptop"];
+in {
+  config = mkIf (builtins.elem deviceType acceptedTypes) {
+    # allows changing system behavior based upon user-selected power profiles
+    # (with `powerprofilesctl` command)
+    services.power-profiles-daemon.enable = true;
+
+    # Power state monitor. Switches power profiles based on charging state.
+    # Plugged in - performance (if available, falls back to balance)
+    # Unplugged - balanced, until below 50%, then power-saver
+    systemd.services."power-monitor" = let
+      dependencies = with pkgs; [
+        coreutils
+        power-profiles-daemon
+        inotify-tools
+        jaq
+      ];
+    in {
+      description = "Power Monitoring Service";
+      environment.PATH = mkForce "/run/wrappers/bin:${makeBinPath dependencies}";
+      script = builtins.readFile ./scripts/power_monitor.sh;
+
+      serviceConfig = {
+        Type = "simple";
+        Restart = "on-failure";
+      };
+
+      wants = ["power-profiles-daemon.service"];
+      wantedBy = ["default.target"];
+    };
+  };
+}

system/roles/laptop/power/auto-cpufreq/power-profiles-daemon/scripts/power_monitor.sh

@@ -0,0 +1,42 @@
+#!/usr/bin/env bash
+
+BAT=$(echo /sys/class/power_supply/BAT*) # only supports single-battery systems
+BAT_STATUS="$BAT/status"
+BAT_CAP="$BAT/capacity"
+
+POWER_SAVE_PERCENT=50 # Enter power-save mode if on bat and below this capacity
+
+HAS_PERFORMANCE="$(powerprofilesctl list | grep performance)"
+
+# monitor loop
+prev=0
+while true; do
+	# read the current state
+	status="$(cat "$BAT_STATUS")"
+	capacity="$(cat "$BAT_CAP")"
+
+	if [[ $status == "Discharging" ]]; then
+		if [[ $capacity -le $POWER_SAVE_PERCENT ]]; then
+			profile="power-saver"
+		else
+			profile="balanced"
+		fi
+	else
+		if [[ -n $HAS_PERFORMANCE ]]; then
+			profile="performance"
+		else
+			profile="balanced"
+		fi
+	fi
+
+	# Set the new profile
+	if [[ $profile != $prev ]]; then
+		echo -en "Setting power profile to ${profile}\n"
+		powerprofilesctl set $profile
+		prev=$profile
+	fi
+
+	# wait for changes in status or capacity files
+	# i.e. for the next power change event
+	inotifywait -qq "$BAT_STATUS" "$BAT_CAP"
+done

system/roles/laptop/power/default.nix

@@ -3,6 +3,10 @@
   deviceType = config.myOptions.device.roles.type;
   acceptedTypes = ["laptop"];
 in {
+  imports = [
+    ./auto-cpufreq
+  ];
+
   config = mkIf (builtins.elem deviceType acceptedTypes) {
     hardware.acpilight.enable = true;
 
@@ -15,48 +19,11 @@ in {
       # handle ACPI events
       acpid.enable = true;
 
-      # allows changing system behavior based upon user-selected power profiles
-      power-profiles-daemon.enable = true;
-
       # temperature target on battery
       undervolt = {
         tempBat = 65; # deg C
         package = pkgs.undervolt;
       };
-
-      # superior power management
-      auto-cpufreq = {
-        enable = true;
-
-        # define the profiles
-        # (you can manually switch between profiles using `powerprofilesctl` cmd)
-        settings = let
-          MHz = x: x * 1000;
-        in {
-          battery = {
-            governor = "powersave";
-            scaling_min_freq = mkDefault (MHz 1200);
-            scaling_max_freq = mkDefault (MHz 1800);
-            turbo = "never";
-          };
-
-          charger = {
-            governor = "performance";
-            scaling_min_freq = mkDefault (MHz 1800);
-            scaling_max_freq = mkDefault (MHz 3800);
-            turbo = "auto";
-          };
-        };
-      };
-
-      # DBus service that provides power management support to applications
-      upower = {
-        enable = true;
-        percentageLow = 15;
-        percentageCritical = 5;
-        percentageAction = 3;
-        criticalPowerAction = "Hibernate";
-      };
     };
 
     boot = {