make a module for vlan

Acked-by: Daniel Barlow <<dan@telent.net>>

modules/vlan/default.nix

@@ -0,0 +1,41 @@
+## VLAN
+## ====
+##
+## Virtual LANs give you the ability to sub-divide a LAN. Linux can
+## accept VLAN tagged traffic and presents each VLAN ID as a
+## different network interface (eg: eth0.100 for VLAN ID 100)
+##
+## Some Liminix devices with multiple ethernet ports are implemented
+## using a network switch connecting the physical ports to the CPU,
+## and require using VLAN in order to send different traffic to
+## different ports (e.g. LAN vs WAN)
+
+{ lib, pkgs, config, ...}:
+let
+  inherit (lib) mkOption types;
+  inherit (pkgs.liminix.services) oneshot;
+  inherit (pkgs) liminix;
+in
+{
+  options = {
+    system.service.vlan = mkOption { type = liminix.lib.types.serviceDefn; };
+  };
+  config.system.service.vlan = liminix.callService ./service.nix {
+    ifname = mkOption {
+      type = types.str;
+      description = "interface name to create";
+    };
+    primary = mkOption {
+      description = "existing physical interface";
+      type = liminix.lib.types.interface;
+    };
+    vid = mkOption {
+      description = "VLAN identifier (VID) in range 1-4094";
+      type = types.str;
+    };
+  };
+  config.kernel.config = {
+    VLAN_8021Q = "y";
+    SWCONFIG = "y"; # not always appropriate, some devices will use DSA
+  };
+}

modules/vlan/service.nix

@@ -0,0 +1,15 @@
+{
+  liminix
+, lib
+}:
+{ ifname, primary, vid } :
+let
+  inherit (liminix.services) oneshot;
+in oneshot rec {
+  name = "${ifname}.link";
+  up = ''
+    ip link add link $(output ${primary} ifname) name ${ifname} type vlan id ${vid}
+    ${liminix.networking.ifup name ifname}
+  '';
+  down = "ip link set down dev ${ifname}";
+}