migrate to libcec with cec socket

nix/cec.nix

@@ -0,0 +1,33 @@
+{ pkgs, ... }:
+{
+  boot.kernelModules = [ "cec" ];
+
+  environment.systemPackages = with pkgs; [
+    libcec
+  ];
+
+  services.udev.extraRules = ''
+    # Pulse-Eight CEC adapter
+    SUBSYSTEM=="tty" ACTION=="add" ATTRS{manufacturer}=="Pulse-Eight" ATTRS{product}=="CEC Adapter" GROUP="video" MODE="0660"
+  '';
+
+  systemd.sockets."cec-client" = {
+    wantedBy = [ "sockets.target" ];
+    socketConfig = {
+      ListenFIFO = "/run/cec.fifo";
+      SocketGroup = "video";
+      SocketMode = "0660";
+    };
+  };
+
+  systemd.services."cec-client" = {
+    wantedBy = [ "multi-user.target" ];
+    serviceConfig = {
+      ExecStart = ''${pkgs.libcec}/bin/cec-client -d 1 -o /dev/ttyACM0'';
+      ExecStop = ''/bin/sh -c "echo q > /run/cec.fifo"'';
+      StandardInput = "socket";
+      StandardOutput = "journal";
+      Restart = "on-failure";
+    };
+  };
+}