net: stmmac: add RX frame steering based on VLAN priority in tc flower

We extend tc flower to support configuration of VLAN priority-based RX
frame steering hardware offloading.

To map VLAN <PCP> to Traffic Class <TC>:
  $ tc filter add dev <IFNAME> parent ffff: protocol 802.1Q flower \
       vlan_prio <PCP> hw_tc <TC>

  Note: <TC> < N whereby "tc qdisc ... num_tc N ..."

To delete all tc flower configurations:
  $ tc qdisc delete dev <IFNAME> ingress
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_tc.c

@@ -598,14 +598,73 @@ static int tc_del_flow(struct stmmac_priv *priv,
 	return ret;
 }
 
+#define VLAN_PRIO_FULL_MASK (0x07)
+
+static int tc_add_vlan_flow(struct stmmac_priv *priv,
+			    struct flow_cls_offload *cls)
+{
+	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_vlan match;
+
+	/* Nothing to do here */
+	if (!dissector_uses_key(dissector, FLOW_DISSECTOR_KEY_VLAN))
+		return -EINVAL;
+
+	if (tc < 0) {
+		netdev_err(priv->dev, "Invalid traffic class\n");
+		return -EINVAL;
+	}
+
+	flow_rule_match_vlan(rule, &match);
+
+	if (match.mask->vlan_priority) {
+		u32 prio;
+
+		if (match.mask->vlan_priority != VLAN_PRIO_FULL_MASK) {
+			netdev_err(priv->dev, "Only full mask is supported for VLAN priority");
+			return -EINVAL;
+		}
+
+		prio = BIT(match.key->vlan_priority);
+		stmmac_rx_queue_prio(priv, priv->hw, prio, tc);
+	}
+
+	return 0;
+}
+
+static int tc_del_vlan_flow(struct stmmac_priv *priv,
+			    struct flow_cls_offload *cls)
+{
+	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);
+
+	/* Nothing to do here */
+	if (!dissector_uses_key(dissector, FLOW_DISSECTOR_KEY_VLAN))
+		return -EINVAL;
+
+	if (tc < 0) {
+		netdev_err(priv->dev, "Invalid traffic class\n");
+		return -EINVAL;
+	}
+
+	stmmac_rx_queue_prio(priv, priv->hw, 0, tc);
+
+	return 0;
+}
+
 static int tc_add_flow_cls(struct stmmac_priv *priv,
 			   struct flow_cls_offload *cls)
 {
 	int ret;
 
 	ret = tc_add_flow(priv, cls);
+	if (!ret)
+		return ret;
 
-	return ret;
+	return tc_add_vlan_flow(priv, cls);
 }
 
 static int tc_del_flow_cls(struct stmmac_priv *priv,
@@ -614,8 +673,10 @@ static int tc_del_flow_cls(struct stmmac_priv *priv,
 	int ret;
 
 	ret = tc_del_flow(priv, cls);
+	if (!ret)
+		return ret;
 
-	return ret;
+	return tc_del_vlan_flow(priv, cls);
 }
 
 static int tc_setup_cls(struct stmmac_priv *priv,