1 files changed, 133 insertions, 0 deletions
diff --git a/nixos/modules/services/audio/alsa.nix b/nixos/modules/services/audio/alsa.nix
new file mode 100644
index 00000000000..0d743ed31da
--- /dev/null
+++ b/nixos/modules/services/audio/alsa.nix
@@ -0,0 +1,133 @@
+# ALSA sound support.
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+
+  inherit (pkgs) alsa-utils;
+
+  pulseaudioEnabled = config.hardware.pulseaudio.enable;
+
+in
+
+{
+  imports = [
+    (mkRenamedOptionModule [ "sound" "enableMediaKeys" ] [ "sound" "mediaKeys" "enable" ])
+  ];
+
+  ###### interface
+
+  options = {
+
+    sound = {
+
+      enable = mkOption {
+        type = types.bool;
+        default = false;
+        description = ''
+          Whether to enable ALSA sound.
+        '';
+      };
+
+      enableOSSEmulation = mkOption {
+        type = types.bool;
+        default = false;
+        description = ''
+          Whether to enable ALSA OSS emulation (with certain cards sound mixing may not work!).
+        '';
+      };
+
+      extraConfig = mkOption {
+        type = types.lines;
+        default = "";
+        example = ''
+          defaults.pcm.!card 3
+        '';
+        description = ''
+          Set addition configuration for system-wide alsa.
+        '';
+      };
+
+      mediaKeys = {
+
+        enable = mkOption {
+          type = types.bool;
+          default = false;
+          description = ''
+            Whether to enable volume and capture control with keyboard media keys.
+
+            You want to leave this disabled if you run a desktop environment
+            like KDE, Gnome, Xfce, etc, as those handle such things themselves.
+            You might want to enable this if you run a minimalistic desktop
+            environment or work from bare linux ttys/framebuffers.
+
+            Enabling this will turn on <option>services.actkbd</option>.
+          '';
+        };
+
+        volumeStep = mkOption {
+          type = types.str;
+          default = "1";
+          example = "1%";
+          description = ''
+            The value by which to increment/decrement volume on media keys.
+
+            See amixer(1) for allowed values.
+          '';
+        };
+
+      };
+
+    };
+
+  };
+
+
+  ###### implementation
+
+  config = mkIf config.sound.enable {
+
+    environment.systemPackages = [ alsa-utils ];
+
+    environment.etc = mkIf (!pulseaudioEnabled && config.sound.extraConfig != "")
+      { "asound.conf".text = config.sound.extraConfig; };
+
+    # ALSA provides a udev rule for restoring volume settings.
+    services.udev.packages = [ alsa-utils ];
+
+    boot.kernelModules = optional config.sound.enableOSSEmulation "snd_pcm_oss";
+
+    systemd.services.alsa-store =
+      { description = "Store Sound Card State";
+        wantedBy = [ "multi-user.target" ];
+        unitConfig.RequiresMountsFor = "/var/lib/alsa";
+        unitConfig.ConditionVirtualization = "!systemd-nspawn";
+        serviceConfig = {
+          Type = "oneshot";
+          RemainAfterExit = true;
+          ExecStart = "${pkgs.coreutils}/bin/mkdir -p /var/lib/alsa";
+          ExecStop = "${alsa-utils}/sbin/alsactl store --ignore";
+        };
+      };
+
+    services.actkbd = mkIf config.sound.mediaKeys.enable {
+      enable = true;
+      bindings = [
+        # "Mute" media key
+        { keys = [ 113 ]; events = [ "key" ];       command = "${alsa-utils}/bin/amixer -q set Master toggle"; }
+
+        # "Lower Volume" media key
+        { keys = [ 114 ]; events = [ "key" "rep" ]; command = "${alsa-utils}/bin/amixer -q set Master ${config.sound.mediaKeys.volumeStep}- unmute"; }
+
+        # "Raise Volume" media key
+        { keys = [ 115 ]; events = [ "key" "rep" ]; command = "${alsa-utils}/bin/amixer -q set Master ${config.sound.mediaKeys.volumeStep}+ unmute"; }
+
+        # "Mic Mute" media key
+        { keys = [ 190 ]; events = [ "key" ];       command = "${alsa-utils}/bin/amixer -q set Capture toggle"; }
+      ];
+    };
+
+  };
+
+}