[RFC PATCH net-next 4/5] net: ethernet: zte: zx279128s: offload flows to and from WLAN ports

[Agustin Santiago Isasmendi <isasmendi.agus@gmail.com>]

Accept flows whose egress or ingress is a mac80211 AP interface, bound
to a WLAN logical port on first use:

- egress: the flowtable hands over the AP interface, or the bridge in
  front of it (mac80211 fills no forwarding path, so the route stops at
  the bridge); one step of the bridge's forwarding path for the next
  hop MAC gives the interface.  The classifier entry's egress field
  takes the WLAN port instead of a bridge port; the fabric then writes
  the rewritten frame to the WLAN RX ring, and the ring delivers it to
  the interface.
- ingress: the flowtable reports the AP interface, or its bridge; the
  flow's pre-NAT source address leads through the bridge's neighbour
  entry and forwarding database to the interface.  The entry is
  installed like a switch port's, and its key is listed for the
  interface's ingress hook, which injects the matching frames so that
  they reach the entry.

The flows of a port are dropped when its interface is unregistered;
their traffic returns to the software path and the flowtable offers
them again once their hardware statistics stop.

Assisted-by: LLM
Signed-off-by: Agustin Santiago Isasmendi <isasmendi.agus@gmail.com>
---
 drivers/net/ethernet/zte/zx279128s-eth.h  |  1 +
 drivers/net/ethernet/zte/zx279128s-ppe.c  | 92 ++++++++++++++++++-----
 drivers/net/ethernet/zte/zx279128s-wlan.c |  9 ++-
 3 files changed, 82 insertions(+), 20 deletions(-)

diff --git a/drivers/net/ethernet/zte/zx279128s-eth.h b/drivers/net/ethernet/zte/zx279128s-eth.h
index b5a547eade35..a5c8df1c60c3 100644
--- a/drivers/net/ethernet/zte/zx279128s-eth.h
+++ b/drivers/net/ethernet/zte/zx279128s-eth.h
@@ -480,6 +480,7 @@ void zx_set_trap_dmac(struct zx_eth_adapter *adapter, int idx, const u8 *mac);
 extern const struct rhashtable_params zx_ppe_ht_params;
 void zx_update_traps(struct zx_eth_adapter *adapter);
 void zx_update_mac_tables(struct zx_eth_adapter *adapter);
+void zx_ppe_wlan_flush(struct zx_eth_adapter *adapter, int wlan_port);
 int zx_eth_setup_tc(struct net_device *dev, enum tc_setup_type type,
 		    void *type_data);
 
diff --git a/drivers/net/ethernet/zte/zx279128s-ppe.c b/drivers/net/ethernet/zte/zx279128s-ppe.c
index ff19d2cc67bd..e02d6bfbddd9 100644
--- a/drivers/net/ethernet/zte/zx279128s-ppe.c
+++ b/drivers/net/ethernet/zte/zx279128s-ppe.c
@@ -37,6 +37,8 @@ struct zx_ppe_entry {
 	u16			flow;
 	u16			nh;
 	u8			subnet;
+	s8			wlan_in;	/* WLAN port of the ingress, or -1 */
+	s8			wlan_out;	/* WLAN port of the egress, or -1 */
 };
 
 const struct rhashtable_params zx_ppe_ht_params = {
@@ -168,12 +170,13 @@ static void zx_ppe_slots(const struct zx_ppe_tuple *t, u16 slot[2])
 }
 
 /*
- * Classifier entry: rewrite index, egress port and forward flag, then the
- * key. Words 1-3 are the same constants in every entry of the stock
- * firmware, and so is the 0x44 in word 0.
+ * Classifier entry: rewrite index, egress port (a bridge port or a WLAN
+ * logical port) and forward flag, then the key. Words 1-3 are the same
+ * constants in every entry of the stock firmware, and so is the 0x44 in
+ * word 0.
  */
-static void zx_ppe_hash_entry(const struct zx_ppe_tuple *t, u16 flow, int port,
-			      u32 w[9])
+static void zx_ppe_hash_entry(const struct zx_ppe_tuple *t, u16 flow,
+			      int egress, u32 w[9])
 {
 	u8 key[20] = {};
 	u16 hw[7];
@@ -185,7 +188,7 @@ static void zx_ppe_hash_entry(const struct zx_ppe_tuple *t, u16 flow, int port,
 	for (i = 0; i < 7; i++)
 		zx_ppe_put_bits(key, 24 + 16 * i, 16, hw[i]);
 	w[0] = FIELD_PREP(ZX_CLA_W0_FLOW, flow) | ZX_CLA_W0_FWD |
-	       FIELD_PREP(ZX_CLA_W0_EGRESS, ZX_BRPORT(port)) | ZX_CLA_W0_BITS;
+	       FIELD_PREP(ZX_CLA_W0_EGRESS, egress) | ZX_CLA_W0_BITS;
 	w[1] = 0xfa11c000;
 	w[2] = 0x00000608;
 	w[3] = 0x80000000;
@@ -305,22 +308,17 @@ static int zx_ppe_flow_add(struct zx_eth_adapter *adapter,
 	__be32 new_saddr, new_daddr;
 	u16 slot[2];
 	u32 w[17];
-	int i, ret, port, subnet, flow, nh;
+	int i, ret, egress, subnet, flow, nh, ingress_ifindex = 0;
+	int wlan_in = -1, wlan_out = -1;
 
 	if (rhashtable_lookup_fast(&adapter->ppe_flows, &f->cookie, zx_ppe_ht_params))
 		return -EEXIST;
 
-	/* the hardware only sees frames from our switch ports */
 	if (flow_rule_match_key(rule, FLOW_DISSECTOR_KEY_META)) {
 		struct flow_match_meta match;
 
 		flow_rule_match_meta(rule, &match);
-		for (i = 0; i < ZX_NUM_PORTS; i++)
-			if (adapter->ports[i] &&
-			    adapter->ports[i]->ifindex == match.key->ingress_ifindex)
-				break;
-		if (i == ZX_NUM_PORTS)
-			return -EOPNOTSUPP;
+		ingress_ifindex = match.key->ingress_ifindex;
 	}
 
 	if (flow_rule_match_key(rule, FLOW_DISSECTOR_KEY_CONTROL)) {
@@ -363,6 +361,23 @@ static int zx_ppe_flow_add(struct zx_eth_adapter *adapter,
 	rw.new_sport = t.sport;
 	rw.new_dport = t.dport;
 
+	/*
+	 * The hardware sees frames from our switch ports, and those a WLAN
+	 * port's ingress hook injects for it (zx279128s-wlan.c).
+	 */
+	if (ingress_ifindex) {
+		for (i = 0; i < ZX_NUM_PORTS; i++)
+			if (adapter->ports[i] &&
+			    adapter->ports[i]->ifindex == ingress_ifindex)
+				break;
+		if (i == ZX_NUM_PORTS) {
+			wlan_in = zx_wlan_port_of_ingress(adapter, ingress_ifindex,
+							  t.saddr);
+			if (wlan_in < 0)
+				return -EOPNOTSUPP;
+		}
+	}
+
 	flow_action_for_each(i, act, &rule->action) {
 		switch (act->id) {
 		case FLOW_ACTION_MANGLE:
@@ -410,11 +425,19 @@ static int zx_ppe_flow_add(struct zx_eth_adapter *adapter,
 		}
 	}
 
-	if (!odev || !zx_eth_is_port(odev))
+	if (!odev)
 		return -EOPNOTSUPP;
-	port = ((struct zx_eth_priv *)netdev_priv(odev))->port;
 	if (!is_valid_ether_addr(eth.h_source) || !is_valid_ether_addr(eth.h_dest))
 		return -EOPNOTSUPP;
+	if (zx_eth_is_port(odev)) {
+		egress = ZX_BRPORT(((struct zx_eth_priv *)netdev_priv(odev))->port);
+	} else {
+		/* an AP interface, or the bridge in front of it */
+		wlan_out = zx_wlan_port_of_egress(adapter, odev, eth.h_dest);
+		if (wlan_out < 0)
+			return -EOPNOTSUPP;
+		egress = ZX_WLAN_PORT(wlan_out);
+	}
 
 	rw.sip = new_saddr != t.saddr;
 	rw.dip = new_daddr != t.daddr;
@@ -462,7 +485,7 @@ static int zx_ppe_flow_add(struct zx_eth_adapter *adapter,
 	ret = zx_pp_write(adapter, ZX_CLA_BASE, ZX_CLA_AGING, slot[1], w, 0);
 	if (ret)
 		goto err_nh;
-	zx_ppe_hash_entry(&t, flow, port, w);
+	zx_ppe_hash_entry(&t, flow, egress, w);
 	ret = zx_pp_write(adapter, ZX_CLA_BASE,
 			  slot[1] < ZX_PPE_HASH0_SIZE ? ZX_CLA_HASH0 : ZX_CLA_HASH1,
 			  slot[1] % ZX_PPE_HASH0_SIZE, w, 9);
@@ -474,11 +497,18 @@ static int zx_ppe_flow_add(struct zx_eth_adapter *adapter,
 	e->flow = flow;
 	e->nh = nh;
 	e->subnet = subnet;
+	e->wlan_in = wlan_in;
+	e->wlan_out = wlan_out;
 	ret = rhashtable_insert_fast(&adapter->ppe_flows, &e->node, zx_ppe_ht_params);
 	if (ret)
 		goto err_entry;
 	set_bit(e->hash, adapter->ppe_hash_used);
 	adapter->ppe_count++;
+	/* the frames of a WLAN ingress flow only reach the entry if injected */
+	if (wlan_in >= 0)
+		zx_wlan_flow_set(adapter, flow,
+				 zx_wlan_flow_key(t.proto, t.saddr, t.daddr,
+						  t.sport, t.dport), wlan_in);
 	return 0;
 
 err_entry:
@@ -499,6 +529,8 @@ static int zx_ppe_flow_add(struct zx_eth_adapter *adapter,
 static void zx_ppe_entry_remove(struct zx_eth_adapter *adapter,
 				struct zx_ppe_entry *e)
 {
+	if (e->wlan_in >= 0)
+		zx_wlan_flow_set(adapter, e->flow, 0, 0);
 	zx_pp_write(adapter, ZX_CLA_BASE,
 		    e->hash < ZX_PPE_HASH0_SIZE ? ZX_CLA_HASH0 : ZX_CLA_HASH1,
 		    e->hash % ZX_PPE_HASH0_SIZE, NULL, 0);
@@ -524,6 +556,32 @@ static int zx_ppe_flow_del(struct zx_eth_adapter *adapter,
 	return 0;
 }
 
+/*
+ * Drop the flows of a WLAN port whose interface goes away; their traffic
+ * returns to the software path, and the flowtable offers them again once
+ * their statistics stop.  Called with ppe_lock held.
+ */
+void zx_ppe_wlan_flush(struct zx_eth_adapter *adapter, int wlan_port)
+{
+	struct rhashtable_iter iter;
+	struct zx_ppe_entry *e;
+
+	rhashtable_walk_enter(&adapter->ppe_flows, &iter);
+	rhashtable_walk_start(&iter);
+	while ((e = rhashtable_walk_next(&iter))) {
+		if (IS_ERR(e))
+			continue;
+		if (e->wlan_in != wlan_port && e->wlan_out != wlan_port)
+			continue;
+		rhashtable_remove_fast(&adapter->ppe_flows, &e->node,
+				       zx_ppe_ht_params);
+		zx_ppe_entry_remove(adapter, e);
+		kfree(e);
+	}
+	rhashtable_walk_stop(&iter);
+	rhashtable_walk_exit(&iter);
+}
+
 /* No packet counters: report use from the entry's hit flag */
 static int zx_ppe_flow_stats(struct zx_eth_adapter *adapter,
 			     struct flow_cls_offload *f)
diff --git a/drivers/net/ethernet/zte/zx279128s-wlan.c b/drivers/net/ethernet/zte/zx279128s-wlan.c
index 17ba32bd993a..6c6f6a36d34f 100644
--- a/drivers/net/ethernet/zte/zx279128s-wlan.c
+++ b/drivers/net/ethernet/zte/zx279128s-wlan.c
@@ -707,9 +707,12 @@ static int zx_wlan_netdev_event(struct notifier_block *nb, unsigned long event,
 	if (event != NETDEV_UNREGISTER || !zx_wlan_is_ap(dev))
 		return NOTIFY_DONE;
 	mutex_lock(&w->adapter->ppe_lock);
-	for (i = 0; i < ZX_WLAN_PORTS; i++)
-		if (w->ports[i].vif == dev)
-			zx_wlan_port_put(w, i);
+	for (i = 0; i < ZX_WLAN_PORTS; i++) {
+		if (w->ports[i].vif != dev)
+			continue;
+		zx_ppe_wlan_flush(w->adapter, i);
+		zx_wlan_port_put(w, i);
+	}
 	mutex_unlock(&w->adapter->ppe_lock);
 	return NOTIFY_DONE;
 }
-- 
2.30.2