net: stmmac: add tc flower filter for EtherType matching

This patch adds basic support for EtherType RX frame steering for
LLDP and PTP using the hardware offload capabilities.

Example steps for setting up RX frame steering for LLDP and PTP:
$ IFDEVNAME=eth0
$ tc qdisc add dev $IFDEVNAME ingress
$ tc qdisc add dev $IFDEVNAME root mqprio num_tc 8 \
     map 0 1 2 3 4 5 6 7 0 0 0 0 0 0 0 0 \
     queues 1@0 1@1 1@2 1@3 1@4 1@5 1@6 1@7 hw 0

For LLDP
$ tc filter add dev $IFDEVNAME parent ffff: protocol 0x88cc \
     flower hw_tc 5
OR
$ tc filter add dev $IFDEVNAME parent ffff: protocol LLDP \
     flower hw_tc 5

For PTP
$ tc filter add dev $IFDEVNAME parent ffff: protocol 0x88f7 \
     flower hw_tc 6

Show tc ingress filter
$ tc filter show dev $IFDEVNAME ingress

v1->v2:
 Thanks to Kurt's and Sebastian's suggestion.
 - change from __be16 to u16 etype
 - change ETHER_TYPE_FULL_MASK to use cpu_to_be16() macro

Signed-off-by: Ong Boon Leong <boon.leong.ong@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/stmmac.h

@@ -174,11 +174,14 @@ struct stmmac_flow_entry {
 /* Rx Frame Steering */
 enum stmmac_rfs_type {
 	STMMAC_RFS_T_VLAN,
+	STMMAC_RFS_T_LLDP,
+	STMMAC_RFS_T_1588,
 	STMMAC_RFS_T_MAX,
 };
 
 struct stmmac_rfs_entry {
 	unsigned long cookie;
+	u16 etype;
 	int in_use;
 	int type;
 	int tc;

drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c

@@ -237,6 +237,8 @@ static int tc_rfs_init(struct stmmac_priv *priv)
 	int i;
 
 	priv->rfs_entries_max[STMMAC_RFS_T_VLAN] = 8;
+	priv->rfs_entries_max[STMMAC_RFS_T_LLDP] = 1;
+	priv->rfs_entries_max[STMMAC_RFS_T_1588] = 1;
 
 	for (i = 0; i < STMMAC_RFS_T_MAX; i++)
 		priv->rfs_entries_total += priv->rfs_entries_max[i];
@@ -451,6 +453,8 @@ static int tc_parse_flow_actions(struct stmmac_priv *priv,
 	return 0;
 }
 
+#define ETHER_TYPE_FULL_MASK	cpu_to_be16(~0)
+
 static int tc_add_basic_flow(struct stmmac_priv *priv,
 			     struct flow_cls_offload *cls,
 			     struct stmmac_flow_entry *entry)
@@ -464,6 +468,7 @@ static int tc_add_basic_flow(struct stmmac_priv *priv,
 		return -EINVAL;
 
 	flow_rule_match_basic(rule, &match);
+
 	entry->ip_proto = match.key->ip_proto;
 	return 0;
 }
@@ -724,6 +729,114 @@ static int tc_del_vlan_flow(struct stmmac_priv *priv,
 	return 0;
 }
 
+static int tc_add_ethtype_flow(struct stmmac_priv *priv,
+			       struct flow_cls_offload *cls)
+{
+	struct stmmac_rfs_entry *entry = tc_find_rfs(priv, cls, false);
+	struct flow_rule *rule = flow_cls_offload_flow_rule(cls);
+	struct flow_dissector *dissector = rule->match.dissector;
+	int tc = tc_classid_to_hwtc(priv->dev, cls->classid);
+	struct flow_match_basic match;
+
+	if (!entry) {
+		entry = tc_find_rfs(priv, cls, true);
+		if (!entry)
+			return -ENOENT;
+	}
+
+	/* Nothing to do here */
+	if (!dissector_uses_key(dissector, FLOW_DISSECTOR_KEY_BASIC))
+		return -EINVAL;
+
+	if (tc < 0) {
+		netdev_err(priv->dev, "Invalid traffic class\n");
+		return -EINVAL;
+	}
+
+	flow_rule_match_basic(rule, &match);
+
+	if (match.mask->n_proto) {
+		u16 etype = ntohs(match.key->n_proto);
+
+		if (match.mask->n_proto != ETHER_TYPE_FULL_MASK) {
+			netdev_err(priv->dev, "Only full mask is supported for EthType filter");
+			return -EINVAL;
+		}
+		switch (etype) {
+		case ETH_P_LLDP:
+			if (priv->rfs_entries_cnt[STMMAC_RFS_T_LLDP] >=
+			    priv->rfs_entries_max[STMMAC_RFS_T_LLDP])
+				return -ENOENT;
+
+			entry->type = STMMAC_RFS_T_LLDP;
+			priv->rfs_entries_cnt[STMMAC_RFS_T_LLDP]++;
+
+			stmmac_rx_queue_routing(priv, priv->hw,
+						PACKET_DCBCPQ, tc);
+			break;
+		case ETH_P_1588:
+			if (priv->rfs_entries_cnt[STMMAC_RFS_T_1588] >=
+			    priv->rfs_entries_max[STMMAC_RFS_T_1588])
+				return -ENOENT;
+
+			entry->type = STMMAC_RFS_T_1588;
+			priv->rfs_entries_cnt[STMMAC_RFS_T_1588]++;
+
+			stmmac_rx_queue_routing(priv, priv->hw,
+						PACKET_PTPQ, tc);
+			break;
+		default:
+			netdev_err(priv->dev, "EthType(0x%x) is not supported", etype);
+			return -EINVAL;
+		}
+
+		entry->in_use = true;
+		entry->cookie = cls->cookie;
+		entry->tc = tc;
+		entry->etype = etype;
+
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
+static int tc_del_ethtype_flow(struct stmmac_priv *priv,
+			       struct flow_cls_offload *cls)
+{
+	struct stmmac_rfs_entry *entry = tc_find_rfs(priv, cls, false);
+
+	if (!entry || !entry->in_use ||
+	    entry->type < STMMAC_RFS_T_LLDP ||
+	    entry->type > STMMAC_RFS_T_1588)
+		return -ENOENT;
+
+	switch (entry->etype) {
+	case ETH_P_LLDP:
+		stmmac_rx_queue_routing(priv, priv->hw,
+					PACKET_DCBCPQ, 0);
+		priv->rfs_entries_cnt[STMMAC_RFS_T_LLDP]--;
+		break;
+	case ETH_P_1588:
+		stmmac_rx_queue_routing(priv, priv->hw,
+					PACKET_PTPQ, 0);
+		priv->rfs_entries_cnt[STMMAC_RFS_T_1588]--;
+		break;
+	default:
+		netdev_err(priv->dev, "EthType(0x%x) is not supported",
+			   entry->etype);
+		return -EINVAL;
+	}
+
+	entry->in_use = false;
+	entry->cookie = 0;
+	entry->tc = 0;
+	entry->etype = 0;
+	entry->type = 0;
+
+	return 0;
+}
+
 static int tc_add_flow_cls(struct stmmac_priv *priv,
 			   struct flow_cls_offload *cls)
 {
@@ -733,6 +846,10 @@ static int tc_add_flow_cls(struct stmmac_priv *priv,
 	if (!ret)
 		return ret;
 
+	ret = tc_add_ethtype_flow(priv, cls);
+	if (!ret)
+		return ret;
+
 	return tc_add_vlan_flow(priv, cls);
 }
 
@@ -745,6 +862,10 @@ static int tc_del_flow_cls(struct stmmac_priv *priv,
 	if (!ret)
 		return ret;
 
+	ret = tc_del_ethtype_flow(priv, cls);
+	if (!ret)
+		return ret;
+
 	return tc_del_vlan_flow(priv, cls);
 }