[PATCH RFC net-next 09/10] net: dsa: mv88e6xxx: Enable mc flood for mrouter port

[Joseph Huang <Joseph.Huang@xxxxxxxxxx>]

When a port turns into an mrouter port, enable multicast flooding
on that port even if multicast flooding is disabled by user config. This
is necessary so that in a distributed system, the multicast packets
can be forwarded to the Querier when the multicast source is attached
to a Non-Querier bridge.

Consider the following scenario:

                 +--------------------+
                 |                    |
                 |      Snooping      |    +------------+
                 |      Bridge 1      |----| Listener 1 |
                 |     (Querier)      |    +------------+
                 |                    |
                 +--------------------+
                           |
                           |
                 +--------------------+
                 |    | mrouter |     |
+-----------+    |    +---------+     |
| MC Source |----|      Snooping      |
+-----------|    |      Bridge 2      |
                 |    (Non-Querier)   |
                 +--------------------+

In this scenario, Listener 1 will never receive multicast traffic
from MC Source if multicast flooding is disabled on the mrouter port on
Snooping Bridge 2.

Signed-off-by: Joseph Huang <Joseph.Huang@xxxxxxxxxx>
---
 drivers/net/dsa/mv88e6xxx/chip.c | 86 ++++++++++++++++++++++++++++++--
 drivers/net/dsa/mv88e6xxx/chip.h |  1 +
 2 files changed, 83 insertions(+), 4 deletions(-)

diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
index 32a613c965b1..9831aa370921 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.c
+++ b/drivers/net/dsa/mv88e6xxx/chip.c
@@ -47,6 +47,7 @@ struct mv88e6xxx_bridge {
 	struct list_head head;
 	struct net_device *br_dev;
 	u16 ports;
+	u16 mrouter_ports;
 	struct list_head br_mdb_list;
 };
 
@@ -2993,6 +2994,7 @@ static void mv88e6xxx_bridge_destroy(struct mv88e6xxx_bridge *mv_bridge)
 	list_del(&mv_bridge->head);
 
 	WARN_ON(mv_bridge->ports);
+	WARN_ON(mv_bridge->mrouter_ports);
 	WARN_ON(!list_empty(&mv_bridge->br_mdb_list));
 	kfree(mv_bridge);
 }
@@ -3010,6 +3012,19 @@ struct mv88e6xxx_bridge *mv88e6xxx_bridge_by_dev(struct mv88e6xxx_chip *chip,
 	return NULL;
 }
 
+static
+struct mv88e6xxx_bridge *mv88e6xxx_bridge_by_port(struct mv88e6xxx_chip *chip,
+						  int port)
+{
+	struct mv88e6xxx_bridge *mv_bridge;
+
+	list_for_each_entry(mv_bridge, &chip->bridge_list, head)
+		if (mv_bridge->ports & BIT(port))
+			return mv_bridge;
+
+	return NULL;
+}
+
 static struct mv88e6xxx_bridge *
 mv88e6xxx_bridge_get(struct mv88e6xxx_chip *chip, struct net_device *br_dev)
 {
@@ -6849,11 +6864,28 @@ static int mv88e6xxx_port_bridge_flags(struct dsa_switch *ds, int port,
 
 	if (flags.mask & BR_MCAST_FLOOD) {
 		bool multicast = !!(flags.val & BR_MCAST_FLOOD);
+		struct mv88e6xxx_bridge *mv_bridge;
+		struct mv88e6xxx_port *p;
+		bool mrouter;
 
-		err = chip->info->ops->port_set_mcast_flood(chip, port,
-							    multicast);
-		if (err)
-			goto out;
+		mv_bridge = mv88e6xxx_bridge_by_port(chip, port);
+		if (!mv_bridge)
+			return -EINVAL;
+
+		p = &chip->ports[port];
+		mrouter = !!(mv_bridge->mrouter_ports & BIT(port));
+
+		if (!mrouter) {
+			err = chip->info->ops->port_set_mcast_flood(chip, port,
+								    multicast);
+			if (err)
+				goto out;
+		}
+
+		if (multicast)
+			p->flags |= MV88E6XXX_PORT_FLAG_MC_FLOOD;
+		else
+			p->flags &= ~MV88E6XXX_PORT_FLAG_MC_FLOOD;
 	}
 
 	if (flags.mask & BR_BCAST_FLOOD) {
@@ -6883,6 +6915,51 @@ static int mv88e6xxx_port_bridge_flags(struct dsa_switch *ds, int port,
 	return err;
 }
 
+static int mv88e6xxx_port_mrouter(struct dsa_switch *ds, int port,
+				  bool mrouter,
+				  struct netlink_ext_ack *extack)
+{
+	struct mv88e6xxx_chip *chip = ds->priv;
+	struct mv88e6xxx_bridge *mv_bridge;
+	struct mv88e6xxx_port *p;
+	bool old_mrouter;
+	bool mc_flood;
+	int err;
+
+	if (!chip->info->ops->port_set_mcast_flood)
+		return -EOPNOTSUPP;
+
+	mv_bridge = mv88e6xxx_bridge_by_port(chip, port);
+	if (!mv_bridge)
+		return -EINVAL;
+
+	old_mrouter = !!(mv_bridge->mrouter_ports & BIT(port));
+	if (mrouter == old_mrouter)
+		return 0;
+
+	p = &chip->ports[port];
+	mc_flood = !!(p->flags & MV88E6XXX_PORT_FLAG_MC_FLOOD);
+
+	mv88e6xxx_reg_lock(chip);
+
+	if (!mc_flood) {
+		err = chip->info->ops->port_set_mcast_flood(chip, port,
+							    mrouter);
+		if (err)
+			goto out;
+	}
+
+	if (mrouter)
+		mv_bridge->mrouter_ports |= BIT(port);
+	else
+		mv_bridge->mrouter_ports &= ~BIT(port);
+
+out:
+	mv88e6xxx_reg_unlock(chip);
+
+	return err;
+}
+
 static bool mv88e6xxx_lag_can_offload(struct dsa_switch *ds,
 				      struct dsa_lag lag,
 				      struct netdev_lag_upper_info *info,
@@ -7199,6 +7276,7 @@ static const struct dsa_switch_ops mv88e6xxx_switch_ops = {
 	.port_bridge_leave	= mv88e6xxx_port_bridge_leave,
 	.port_pre_bridge_flags	= mv88e6xxx_port_pre_bridge_flags,
 	.port_bridge_flags	= mv88e6xxx_port_bridge_flags,
+	.port_mrouter		= mv88e6xxx_port_mrouter,
 	.port_stp_state_set	= mv88e6xxx_port_stp_state_set,
 	.port_mst_state_set	= mv88e6xxx_port_mst_state_set,
 	.port_fast_age		= mv88e6xxx_port_fast_age,
diff --git a/drivers/net/dsa/mv88e6xxx/chip.h b/drivers/net/dsa/mv88e6xxx/chip.h
index 205f6777c2ac..47e056dc7925 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.h
+++ b/drivers/net/dsa/mv88e6xxx/chip.h
@@ -274,6 +274,7 @@ struct mv88e6xxx_vlan {
 
 /* MacAuth Bypass Control Flag */
 #define MV88E6XXX_PORT_FLAG_MAB		BIT(0)
+#define MV88E6XXX_PORT_FLAG_MC_FLOOD	BIT(1)
 
 struct mv88e6xxx_port {
 	struct mv88e6xxx_chip *chip;
-- 
2.17.1