net: dsa: tag_8021q: add support for imprecise RX based on the VBID

The sja1105 switch can't populate the PORT field of the tag_8021q header
when sending a frame to the CPU with a non-zero VBID.

Similar to dsa_find_designated_bridge_port_by_vid() which performs
imprecise RX for VLAN-aware bridges, let's introduce a helper in
tag_8021q for performing imprecise RX based on the VLAN that it has
allocated for a VLAN-unaware bridge.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 36 insertions, 2 deletions

diff --git a/net/dsa/tag_8021q.c b/net/dsa/tag_8021q.c
index c6555003f5df..1cf245a6f18e 100644
--- a/net/dsa/tag_8021q.c
+++ b/net/dsa/tag_8021q.c
@@ -32,7 +32,7 @@
  * VBID - { VID[9], VID[5:4] }:
  *	Virtual bridge ID. If between 1 and 7, packet targets the broadcast
  *	domain of a bridge. If transmitted as zero, packet targets a single
- *	port. Field only valid on transmit, must be ignored on receive.
+ *	port.
  *
  * PORT - VID[3:0]:
  *	Index of switch port. Must be between 0 and 15.
@@ -533,7 +533,37 @@ struct sk_buff *dsa_8021q_xmit(struct sk_buff *skb, struct net_device *netdev,
 }
 EXPORT_SYMBOL_GPL(dsa_8021q_xmit);
 
-void dsa_8021q_rcv(struct sk_buff *skb, int *source_port, int *switch_id)
+struct net_device *dsa_tag_8021q_find_port_by_vbid(struct net_device *master,
+						   int vbid)
+{
+	struct dsa_port *cpu_dp = master->dsa_ptr;
+	struct dsa_switch_tree *dst = cpu_dp->dst;
+	struct dsa_port *dp;
+
+	if (WARN_ON(!vbid))
+		return NULL;
+
+	dsa_tree_for_each_user_port(dp, dst) {
+		if (!dp->bridge)
+			continue;
+
+		if (dp->stp_state != BR_STATE_LEARNING &&
+		    dp->stp_state != BR_STATE_FORWARDING)
+			continue;
+
+		if (dp->cpu_dp != cpu_dp)
+			continue;
+
+		if (dsa_port_bridge_num_get(dp) == vbid)
+			return dp->slave;
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(dsa_tag_8021q_find_port_by_vbid);
+
+void dsa_8021q_rcv(struct sk_buff *skb, int *source_port, int *switch_id,
+		   int *vbid)
 {
 	u16 vid, tci;
 
@@ -550,6 +580,10 @@ void dsa_8021q_rcv(struct sk_buff *skb, int *source_port, int *switch_id)
 
 	*source_port = dsa_8021q_rx_source_port(vid);
 	*switch_id = dsa_8021q_rx_switch_id(vid);
+
+	if (vbid)
+		*vbid = dsa_tag_8021q_rx_vbid(vid);
+
 	skb->priority = (tci & VLAN_PRIO_MASK) >> VLAN_PRIO_SHIFT;
 }
 EXPORT_SYMBOL_GPL(dsa_8021q_rcv);