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>

include/linux/dsa/8021q.h

@@ -41,7 +41,11 @@ void dsa_tag_8021q_bridge_leave(struct dsa_switch *ds, int port,
 struct sk_buff *dsa_8021q_xmit(struct sk_buff *skb, struct net_device *netdev,
 			       u16 tpid, u16 tci);
 
-void dsa_8021q_rcv(struct sk_buff *skb, int *source_port, int *switch_id);
+void dsa_8021q_rcv(struct sk_buff *skb, int *source_port, int *switch_id,
+		   int *vbid);
+
+struct net_device *dsa_tag_8021q_find_port_by_vbid(struct net_device *master,
+						   int vbid);
 
 u16 dsa_8021q_bridge_tx_fwd_offload_vid(unsigned int bridge_num);
 

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);

net/dsa/tag_ocelot_8021q.c

@@ -77,7 +77,7 @@ static struct sk_buff *ocelot_rcv(struct sk_buff *skb,
 {
 	int src_port, switch_id;
 
-	dsa_8021q_rcv(skb, &src_port, &switch_id);
+	dsa_8021q_rcv(skb, &src_port, &switch_id, NULL);
 
 	skb->dev = dsa_master_find_slave(netdev, switch_id, src_port);
 	if (!skb->dev)

net/dsa/tag_sja1105.c

@@ -509,7 +509,7 @@ static bool sja1110_skb_has_inband_control_extension(const struct sk_buff *skb)
  * packet.
  */
 static void sja1105_vlan_rcv(struct sk_buff *skb, int *source_port,
-			     int *switch_id, u16 *vid)
+			     int *switch_id, int *vbid, u16 *vid)
 {
 	struct vlan_ethhdr *hdr = (struct vlan_ethhdr *)skb_mac_header(skb);
 	u16 vlan_tci;
@@ -519,8 +519,8 @@ static void sja1105_vlan_rcv(struct sk_buff *skb, int *source_port,
 	else
 		vlan_tci = ntohs(hdr->h_vlan_TCI);
 
-	if (vid_is_dsa_8021q_rxvlan(vlan_tci & VLAN_VID_MASK))
-		return dsa_8021q_rcv(skb, source_port, switch_id);
+	if (vid_is_dsa_8021q(vlan_tci & VLAN_VID_MASK))
+		return dsa_8021q_rcv(skb, source_port, switch_id, vbid);
 
 	/* Try our best with imprecise RX */
 	*vid = vlan_tci & VLAN_VID_MASK;
@@ -529,7 +529,7 @@ static void sja1105_vlan_rcv(struct sk_buff *skb, int *source_port,
 static struct sk_buff *sja1105_rcv(struct sk_buff *skb,
 				   struct net_device *netdev)
 {
-	int source_port = -1, switch_id = -1;
+	int source_port = -1, switch_id = -1, vbid = -1;
 	struct sja1105_meta meta = {0};
 	struct ethhdr *hdr;
 	bool is_link_local;
@@ -542,7 +542,7 @@ static struct sk_buff *sja1105_rcv(struct sk_buff *skb,
 
 	if (sja1105_skb_has_tag_8021q(skb)) {
 		/* Normal traffic path. */
-		sja1105_vlan_rcv(skb, &source_port, &switch_id, &vid);
+		sja1105_vlan_rcv(skb, &source_port, &switch_id, &vbid, &vid);
 	} else if (is_link_local) {
 		/* Management traffic path. Switch embeds the switch ID and
 		 * port ID into bytes of the destination MAC, courtesy of
@@ -561,7 +561,9 @@ static struct sk_buff *sja1105_rcv(struct sk_buff *skb,
 		return NULL;
 	}
 
-	if (source_port == -1 || switch_id == -1)
+	if (vbid >= 1)
+		skb->dev = dsa_tag_8021q_find_port_by_vbid(netdev, vbid);
+	else if (source_port == -1 || switch_id == -1)
 		skb->dev = dsa_find_designated_bridge_port_by_vid(netdev, vid);
 	else
 		skb->dev = dsa_master_find_slave(netdev, switch_id, source_port);
@@ -686,7 +688,7 @@ static struct sk_buff *sja1110_rcv_inband_control_extension(struct sk_buff *skb,
 static struct sk_buff *sja1110_rcv(struct sk_buff *skb,
 				   struct net_device *netdev)
 {
-	int source_port = -1, switch_id = -1;
+	int source_port = -1, switch_id = -1, vbid = -1;
 	bool host_only = false;
 	u16 vid = 0;
 
@@ -700,9 +702,11 @@ static struct sk_buff *sja1110_rcv(struct sk_buff *skb,
 
 	/* Packets with in-band control extensions might still have RX VLANs */
 	if (likely(sja1105_skb_has_tag_8021q(skb)))
-		sja1105_vlan_rcv(skb, &source_port, &switch_id, &vid);
+		sja1105_vlan_rcv(skb, &source_port, &switch_id, &vbid, &vid);
 
-	if (source_port == -1 || switch_id == -1)
+	if (vbid >= 1)
+		skb->dev = dsa_tag_8021q_find_port_by_vbid(netdev, vbid);
+	else if (source_port == -1 || switch_id == -1)
 		skb->dev = dsa_find_designated_bridge_port_by_vid(netdev, vid);
 	else
 		skb->dev = dsa_master_find_slave(netdev, switch_id, source_port);