base-files: uci-defaults: support requesting untagged switch port configuration

Introduce support for a new [0-9]u@netdev syntax to ucidev_add_switch() to let
board.d network files request default network switch configurations which do
not use tagged CPU ports.

This commit itself has no effect on generated configurations at the moment
since we still emit untagged configurations by default but it allows boards to
opt-out from default tagged configs in case we start emitting tagged settings
by default.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

package/base-files/files/lib/functions/uci-defaults.sh

@@ -94,7 +94,7 @@ ucidef_set_interface_raw() {
 }
 
 _ucidef_add_switch_port() {
-	# inherited: $num $device $need_tag $role $index $prev_role
+	# inherited: $num $device $need_tag $want_untag $role $index $prev_role
 	# inherited: $n_cpu $n_ports $n_vlan $cpu0 $cpu1 $cpu2 $cpu3 $cpu4 $cpu5
 
 	n_ports=$((n_ports + 1))
@@ -104,6 +104,7 @@ _ucidef_add_switch_port() {
 			json_add_int num "$num"
 			[ -n "$device"     ] && json_add_string  device     "$device"
 			[ -n "$need_tag"   ] && json_add_boolean need_tag   "$need_tag"
+			[ -n "$want_untag" ] && json_add_boolean want_untag "$want_untag"
 			[ -n "$role"       ] && json_add_string  role       "$role"
 			[ -n "$index"      ] && json_add_int     index      "$index"
 		json_close_object
@@ -140,7 +141,7 @@ _ucidef_add_switch_port() {
 
 _ucidef_finish_switch_roles() {
 	# inherited: $name $n_cpu $n_vlan $cpu0 $cpu1 $cpu2 $cpu3 $cpu4 $cpu5
-	local index role roles num device need_tag port ports
+	local index role roles num device need_tag want_untag port ports
 
 	json_select switch
 		json_select "$name"
@@ -155,7 +156,7 @@ _ucidef_finish_switch_roles() {
 			json_select "$name"
 				json_select ports
 					json_select "$port"
-						json_get_vars num device need_tag
+						json_get_vars num device need_tag want_untag
 					json_select ..
 				json_select ..
 
@@ -207,10 +208,15 @@ ucidef_add_switch() {
 						num="${port%%@*}"
 						device="${port##*@}"
 						need_tag=0
+						want_untag=0
 						[ "${num%t}" != "$num" ] && {
 							num="${num%t}"
 							need_tag=1
 						}
+						[ "${num%u}" != "$num" ] && {
+							num="${num%u}"
+							want_untag=1
+						}
 					;;
 					[0-9]*:*:[0-9]*)
 						num="${port%%:*}"
@@ -227,7 +233,7 @@ ucidef_add_switch() {
 					_ucidef_add_switch_port
 				fi
 
-				unset num device role index need_tag
+				unset num device role index need_tag want_untag
 			done
 		json_select ..
 	json_select ..