1 files changed, 465 insertions, 58 deletions

diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c
index c0ffc7a2b65f..4d4956ed303b 100644
--- a/net/dsa/dsa2.c
+++ b/net/dsa/dsa2.c
@@ -21,8 +21,107 @@
 static DEFINE_MUTEX(dsa2_mutex);
 LIST_HEAD(dsa_tree_list);
 
-static const struct devlink_ops dsa_devlink_ops = {
-};
+/**
+ * dsa_tree_notify - Execute code for all switches in a DSA switch tree.
+ * @dst: collection of struct dsa_switch devices to notify.
+ * @e: event, must be of type DSA_NOTIFIER_*
+ * @v: event-specific value.
+ *
+ * Given a struct dsa_switch_tree, this can be used to run a function once for
+ * each member DSA switch. The other alternative of traversing the tree is only
+ * through its ports list, which does not uniquely list the switches.
+ */
+int dsa_tree_notify(struct dsa_switch_tree *dst, unsigned long e, void *v)
+{
+	struct raw_notifier_head *nh = &dst->nh;
+	int err;
+
+	err = raw_notifier_call_chain(nh, e, v);
+
+	return notifier_to_errno(err);
+}
+
+/**
+ * dsa_broadcast - Notify all DSA trees in the system.
+ * @e: event, must be of type DSA_NOTIFIER_*
+ * @v: event-specific value.
+ *
+ * Can be used to notify the switching fabric of events such as cross-chip
+ * bridging between disjoint trees (such as islands of tagger-compatible
+ * switches bridged by an incompatible middle switch).
+ */
+int dsa_broadcast(unsigned long e, void *v)
+{
+	struct dsa_switch_tree *dst;
+	int err = 0;
+
+	list_for_each_entry(dst, &dsa_tree_list, list) {
+		err = dsa_tree_notify(dst, e, v);
+		if (err)
+			break;
+	}
+
+	return err;
+}
+
+/**
+ * dsa_lag_map() - Map LAG netdev to a linear LAG ID
+ * @dst: Tree in which to record the mapping.
+ * @lag: Netdev that is to be mapped to an ID.
+ *
+ * dsa_lag_id/dsa_lag_dev can then be used to translate between the
+ * two spaces. The size of the mapping space is determined by the
+ * driver by setting ds->num_lag_ids. It is perfectly legal to leave
+ * it unset if it is not needed, in which case these functions become
+ * no-ops.
+ */
+void dsa_lag_map(struct dsa_switch_tree *dst, struct net_device *lag)
+{
+	unsigned int id;
+
+	if (dsa_lag_id(dst, lag) >= 0)
+		/* Already mapped */
+		return;
+
+	for (id = 0; id < dst->lags_len; id++) {
+		if (!dsa_lag_dev(dst, id)) {
+			dst->lags[id] = lag;
+			return;
+		}
+	}
+
+	/* No IDs left, which is OK. Some drivers do not need it. The
+	 * ones that do, e.g. mv88e6xxx, will discover that dsa_lag_id
+	 * returns an error for this device when joining the LAG. The
+	 * driver can then return -EOPNOTSUPP back to DSA, which will
+	 * fall back to a software LAG.
+	 */
+}
+
+/**
+ * dsa_lag_unmap() - Remove a LAG ID mapping
+ * @dst: Tree in which the mapping is recorded.
+ * @lag: Netdev that was mapped.
+ *
+ * As there may be multiple users of the mapping, it is only removed
+ * if there are no other references to it.
+ */
+void dsa_lag_unmap(struct dsa_switch_tree *dst, struct net_device *lag)
+{
+	struct dsa_port *dp;
+	unsigned int id;
+
+	dsa_lag_foreach_port(dp, dst, lag)
+		/* There are remaining users of this mapping */
+		return;
+
+	dsa_lags_foreach_id(id, dst) {
+		if (dsa_lag_dev(dst, id) == lag) {
+			dst->lags[id] = NULL;
+			break;
+		}
+	}
+}
 
 struct dsa_switch *dsa_switch_find(int tree_index, int sw_index)
 {
@@ -80,6 +179,8 @@ static struct dsa_switch_tree *dsa_tree_alloc(int index)
 
 static void dsa_tree_free(struct dsa_switch_tree *dst)
 {
+	if (dst->tag_ops)
+		dsa_tag_driver_put(dst->tag_ops);
 	list_del(&dst->list);
 	kfree(dst);
 }
@@ -254,22 +355,11 @@ static void dsa_tree_teardown_default_cpu(struct dsa_switch_tree *dst)
 
 static int dsa_port_setup(struct dsa_port *dp)
 {
-	struct dsa_switch *ds = dp->ds;
-	struct dsa_switch_tree *dst = ds->dst;
-	const unsigned char *id = (const unsigned char *)&dst->index;
-	const unsigned char len = sizeof(dst->index);
 	struct devlink_port *dlp = &dp->devlink_port;
 	bool dsa_port_link_registered = false;
-	bool devlink_port_registered = false;
-	struct devlink_port_attrs attrs = {};
-	struct devlink *dl = ds->devlink;
 	bool dsa_port_enabled = false;
 	int err = 0;
 
-	attrs.phys.port_number = dp->index;
-	memcpy(attrs.switch_id.id, id, len);
-	attrs.switch_id.id_len = len;
-
 	if (dp->setup)
 		return 0;
 
@@ -278,14 +368,6 @@ static int dsa_port_setup(struct dsa_port *dp)
 		dsa_port_disable(dp);
 		break;
 	case DSA_PORT_TYPE_CPU:
-		memset(dlp, 0, sizeof(*dlp));
-		attrs.flavour = DEVLINK_PORT_FLAVOUR_CPU;
-		devlink_port_attrs_set(dlp, &attrs);
-		err = devlink_port_register(dl, dlp, dp->index);
-		if (err)
-			break;
-		devlink_port_registered = true;
-
 		err = dsa_port_link_register_of(dp);
 		if (err)
 			break;
@@ -298,14 +380,6 @@ static int dsa_port_setup(struct dsa_port *dp)
 
 		break;
 	case DSA_PORT_TYPE_DSA:
-		memset(dlp, 0, sizeof(*dlp));
-		attrs.flavour = DEVLINK_PORT_FLAVOUR_DSA;
-		devlink_port_attrs_set(dlp, &attrs);
-		err = devlink_port_register(dl, dlp, dp->index);
-		if (err)
-			break;
-		devlink_port_registered = true;
-
 		err = dsa_port_link_register_of(dp);
 		if (err)
 			break;
@@ -318,14 +392,6 @@ static int dsa_port_setup(struct dsa_port *dp)
 
 		break;
 	case DSA_PORT_TYPE_USER:
-		memset(dlp, 0, sizeof(*dlp));
-		attrs.flavour = DEVLINK_PORT_FLAVOUR_PHYSICAL;
-		devlink_port_attrs_set(dlp, &attrs);
-		err = devlink_port_register(dl, dlp, dp->index);
-		if (err)
-			break;
-		devlink_port_registered = true;
-
 		dp->mac = of_get_mac_address(dp->dn);
 		err = dsa_slave_create(dp);
 		if (err)
@@ -339,8 +405,6 @@ static int dsa_port_setup(struct dsa_port *dp)
 		dsa_port_disable(dp);
 	if (err && dsa_port_link_registered)
 		dsa_port_link_unregister_of(dp);
-	if (err && devlink_port_registered)
-		devlink_port_unregister(dlp);
 	if (err)
 		return err;
 
@@ -349,6 +413,48 @@ static int dsa_port_setup(struct dsa_port *dp)
 	return 0;
 }
 
+static int dsa_port_devlink_setup(struct dsa_port *dp)
+{
+	struct devlink_port *dlp = &dp->devlink_port;
+	struct dsa_switch_tree *dst = dp->ds->dst;
+	struct devlink_port_attrs attrs = {};
+	struct devlink *dl = dp->ds->devlink;
+	const unsigned char *id;
+	unsigned char len;
+	int err;
+
+	id = (const unsigned char *)&dst->index;
+	len = sizeof(dst->index);
+
+	attrs.phys.port_number = dp->index;
+	memcpy(attrs.switch_id.id, id, len);
+	attrs.switch_id.id_len = len;
+	memset(dlp, 0, sizeof(*dlp));
+
+	switch (dp->type) {
+	case DSA_PORT_TYPE_UNUSED:
+		attrs.flavour = DEVLINK_PORT_FLAVOUR_UNUSED;
+		break;
+	case DSA_PORT_TYPE_CPU:
+		attrs.flavour = DEVLINK_PORT_FLAVOUR_CPU;
+		break;
+	case DSA_PORT_TYPE_DSA:
+		attrs.flavour = DEVLINK_PORT_FLAVOUR_DSA;
+		break;
+	case DSA_PORT_TYPE_USER:
+		attrs.flavour = DEVLINK_PORT_FLAVOUR_PHYSICAL;
+		break;
+	}
+
+	devlink_port_attrs_set(dlp, &attrs);
+	err = devlink_port_register(dl, dlp, dp->index);
+
+	if (!err)
+		dp->devlink_port_setup = true;
+
+	return err;
+}
+
 static void dsa_port_teardown(struct dsa_port *dp)
 {
 	struct devlink_port *dlp = &dp->devlink_port;
@@ -356,22 +462,20 @@ static void dsa_port_teardown(struct dsa_port *dp)
 	if (!dp->setup)
 		return;
 
+	devlink_port_type_clear(dlp);
+
 	switch (dp->type) {
 	case DSA_PORT_TYPE_UNUSED:
 		break;
 	case DSA_PORT_TYPE_CPU:
 		dsa_port_disable(dp);
-		dsa_tag_driver_put(dp->tag_ops);
-		devlink_port_unregister(dlp);
 		dsa_port_link_unregister_of(dp);
 		break;
 	case DSA_PORT_TYPE_DSA:
 		dsa_port_disable(dp);
-		devlink_port_unregister(dlp);
 		dsa_port_link_unregister_of(dp);
 		break;
 	case DSA_PORT_TYPE_USER:
-		devlink_port_unregister(dlp);
 		if (dp->slave) {
 			dsa_slave_destroy(dp->slave);
 			dp->slave = NULL;
@@ -382,9 +486,192 @@ static void dsa_port_teardown(struct dsa_port *dp)
 	dp->setup = false;
 }
 
+static void dsa_port_devlink_teardown(struct dsa_port *dp)
+{
+	struct devlink_port *dlp = &dp->devlink_port;
+
+	if (dp->devlink_port_setup)
+		devlink_port_unregister(dlp);
+	dp->devlink_port_setup = false;
+}
+
+static int dsa_devlink_info_get(struct devlink *dl,
+				struct devlink_info_req *req,
+				struct netlink_ext_ack *extack)
+{
+	struct dsa_switch *ds = dsa_devlink_to_ds(dl);
+
+	if (ds->ops->devlink_info_get)
+		return ds->ops->devlink_info_get(ds, req, extack);
+
+	return -EOPNOTSUPP;
+}
+
+static int dsa_devlink_sb_pool_get(struct devlink *dl,
+				   unsigned int sb_index, u16 pool_index,
+				   struct devlink_sb_pool_info *pool_info)
+{
+	struct dsa_switch *ds = dsa_devlink_to_ds(dl);
+
+	if (!ds->ops->devlink_sb_pool_get)
+		return -EOPNOTSUPP;
+
+	return ds->ops->devlink_sb_pool_get(ds, sb_index, pool_index,
+					    pool_info);
+}
+
+static int dsa_devlink_sb_pool_set(struct devlink *dl, unsigned int sb_index,
+				   u16 pool_index, u32 size,
+				   enum devlink_sb_threshold_type threshold_type,
+				   struct netlink_ext_ack *extack)
+{
+	struct dsa_switch *ds = dsa_devlink_to_ds(dl);
+
+	if (!ds->ops->devlink_sb_pool_set)
+		return -EOPNOTSUPP;
+
+	return ds->ops->devlink_sb_pool_set(ds, sb_index, pool_index, size,
+					    threshold_type, extack);
+}
+
+static int dsa_devlink_sb_port_pool_get(struct devlink_port *dlp,
+					unsigned int sb_index, u16 pool_index,
+					u32 *p_threshold)
+{
+	struct dsa_switch *ds = dsa_devlink_port_to_ds(dlp);
+	int port = dsa_devlink_port_to_port(dlp);
+
+	if (!ds->ops->devlink_sb_port_pool_get)
+		return -EOPNOTSUPP;
+
+	return ds->ops->devlink_sb_port_pool_get(ds, port, sb_index,
+						 pool_index, p_threshold);
+}
+
+static int dsa_devlink_sb_port_pool_set(struct devlink_port *dlp,
+					unsigned int sb_index, u16 pool_index,
+					u32 threshold,
+					struct netlink_ext_ack *extack)
+{
+	struct dsa_switch *ds = dsa_devlink_port_to_ds(dlp);
+	int port = dsa_devlink_port_to_port(dlp);
+
+	if (!ds->ops->devlink_sb_port_pool_set)
+		return -EOPNOTSUPP;
+
+	return ds->ops->devlink_sb_port_pool_set(ds, port, sb_index,
+						 pool_index, threshold, extack);
+}
+
+static int
+dsa_devlink_sb_tc_pool_bind_get(struct devlink_port *dlp,
+				unsigned int sb_index, u16 tc_index,
+				enum devlink_sb_pool_type pool_type,
+				u16 *p_pool_index, u32 *p_threshold)
+{
+	struct dsa_switch *ds = dsa_devlink_port_to_ds(dlp);
+	int port = dsa_devlink_port_to_port(dlp);
+
+	if (!ds->ops->devlink_sb_tc_pool_bind_get)
+		return -EOPNOTSUPP;
+
+	return ds->ops->devlink_sb_tc_pool_bind_get(ds, port, sb_index,
+						    tc_index, pool_type,
+						    p_pool_index, p_threshold);
+}
+
+static int
+dsa_devlink_sb_tc_pool_bind_set(struct devlink_port *dlp,
+				unsigned int sb_index, u16 tc_index,
+				enum devlink_sb_pool_type pool_type,
+				u16 pool_index, u32 threshold,
+				struct netlink_ext_ack *extack)
+{
+	struct dsa_switch *ds = dsa_devlink_port_to_ds(dlp);
+	int port = dsa_devlink_port_to_port(dlp);
+
+	if (!ds->ops->devlink_sb_tc_pool_bind_set)
+		return -EOPNOTSUPP;
+
+	return ds->ops->devlink_sb_tc_pool_bind_set(ds, port, sb_index,
+						    tc_index, pool_type,
+						    pool_index, threshold,
+						    extack);
+}
+
+static int dsa_devlink_sb_occ_snapshot(struct devlink *dl,
+				       unsigned int sb_index)
+{
+	struct dsa_switch *ds = dsa_devlink_to_ds(dl);
+
+	if (!ds->ops->devlink_sb_occ_snapshot)
+		return -EOPNOTSUPP;
+
+	return ds->ops->devlink_sb_occ_snapshot(ds, sb_index);
+}
+
+static int dsa_devlink_sb_occ_max_clear(struct devlink *dl,
+					unsigned int sb_index)
+{
+	struct dsa_switch *ds = dsa_devlink_to_ds(dl);
+
+	if (!ds->ops->devlink_sb_occ_max_clear)
+		return -EOPNOTSUPP;
+
+	return ds->ops->devlink_sb_occ_max_clear(ds, sb_index);
+}
+
+static int dsa_devlink_sb_occ_port_pool_get(struct devlink_port *dlp,
+					    unsigned int sb_index,
+					    u16 pool_index, u32 *p_cur,
+					    u32 *p_max)
+{
+	struct dsa_switch *ds = dsa_devlink_port_to_ds(dlp);
+	int port = dsa_devlink_port_to_port(dlp);
+
+	if (!ds->ops->devlink_sb_occ_port_pool_get)
+		return -EOPNOTSUPP;
+
+	return ds->ops->devlink_sb_occ_port_pool_get(ds, port, sb_index,
+						     pool_index, p_cur, p_max);
+}
+
+static int
+dsa_devlink_sb_occ_tc_port_bind_get(struct devlink_port *dlp,
+				    unsigned int sb_index, u16 tc_index,
+				    enum devlink_sb_pool_type pool_type,
+				    u32 *p_cur, u32 *p_max)
+{
+	struct dsa_switch *ds = dsa_devlink_port_to_ds(dlp);
+	int port = dsa_devlink_port_to_port(dlp);
+
+	if (!ds->ops->devlink_sb_occ_tc_port_bind_get)
+		return -EOPNOTSUPP;
+
+	return ds->ops->devlink_sb_occ_tc_port_bind_get(ds, port,
+							sb_index, tc_index,
+							pool_type, p_cur,
+							p_max);
+}
+
+static const struct devlink_ops dsa_devlink_ops = {
+	.info_get			= dsa_devlink_info_get,
+	.sb_pool_get			= dsa_devlink_sb_pool_get,
+	.sb_pool_set			= dsa_devlink_sb_pool_set,
+	.sb_port_pool_get		= dsa_devlink_sb_port_pool_get,
+	.sb_port_pool_set		= dsa_devlink_sb_port_pool_set,
+	.sb_tc_pool_bind_get		= dsa_devlink_sb_tc_pool_bind_get,
+	.sb_tc_pool_bind_set		= dsa_devlink_sb_tc_pool_bind_set,
+	.sb_occ_snapshot		= dsa_devlink_sb_occ_snapshot,
+	.sb_occ_max_clear		= dsa_devlink_sb_occ_max_clear,
+	.sb_occ_port_pool_get		= dsa_devlink_sb_occ_port_pool_get,
+	.sb_occ_tc_port_bind_get	= dsa_devlink_sb_occ_tc_port_bind_get,
+};
+
 static int dsa_switch_setup(struct dsa_switch *ds)
 {
 	struct dsa_devlink_priv *dl_priv;
+	struct dsa_port *dp;
 	int err;
 
 	if (ds->setup)
@@ -410,9 +697,22 @@ static int dsa_switch_setup(struct dsa_switch *ds)
 	if (err)
 		goto free_devlink;
 
+	/* Setup devlink port instances now, so that the switch
+	 * setup() can register regions etc, against the ports
+	 */
+	list_for_each_entry(dp, &ds->dst->ports, list) {
+		if (dp->ds == ds) {
+			err = dsa_port_devlink_setup(dp);
+			if (err)
+				goto unregister_devlink_ports;
+		}
+	}
+
 	err = dsa_switch_register_notifier(ds);
 	if (err)
-		goto unregister_devlink;
+		goto unregister_devlink_ports;
+
+	ds->configure_vlan_while_not_filtering = true;
 
 	err = ds->ops->setup(ds);
 	if (err < 0)
@@ -424,23 +724,29 @@ static int dsa_switch_setup(struct dsa_switch *ds)
 		ds->slave_mii_bus = devm_mdiobus_alloc(ds->dev);
 		if (!ds->slave_mii_bus) {
 			err = -ENOMEM;
-			goto unregister_notifier;
+			goto teardown;
 		}
 
 		dsa_slave_mii_bus_init(ds);
 
 		err = mdiobus_register(ds->slave_mii_bus);
 		if (err < 0)
-			goto unregister_notifier;
+			goto teardown;
 	}
 
 	ds->setup = true;
 
 	return 0;
 
+teardown:
+	if (ds->ops->teardown)
+		ds->ops->teardown(ds);
 unregister_notifier:
 	dsa_switch_unregister_notifier(ds);
-unregister_devlink:
+unregister_devlink_ports:
+	list_for_each_entry(dp, &ds->dst->ports, list)
+		if (dp->ds == ds)
+			dsa_port_devlink_teardown(dp);
 	devlink_unregister(ds->devlink);
 free_devlink:
 	devlink_free(ds->devlink);
@@ -451,6 +757,8 @@ free_devlink:
 
 static void dsa_switch_teardown(struct dsa_switch *ds)
 {
+	struct dsa_port *dp;
+
 	if (!ds->setup)
 		return;
 
@@ -463,6 +771,9 @@ static void dsa_switch_teardown(struct dsa_switch *ds)
 		ds->ops->teardown(ds);
 
 	if (ds->devlink) {
+		list_for_each_entry(dp, &ds->dst->ports, list)
+			if (dp->ds == ds)
+				dsa_port_devlink_teardown(dp);
 		devlink_unregister(ds->devlink);
 		devlink_free(ds->devlink);
 		ds->devlink = NULL;
@@ -536,6 +847,32 @@ static void dsa_tree_teardown_master(struct dsa_switch_tree *dst)
 			dsa_master_teardown(dp->master);
 }
 
+static int dsa_tree_setup_lags(struct dsa_switch_tree *dst)
+{
+	unsigned int len = 0;
+	struct dsa_port *dp;
+
+	list_for_each_entry(dp, &dst->ports, list) {
+		if (dp->ds->num_lag_ids > len)
+			len = dp->ds->num_lag_ids;
+	}
+
+	if (!len)
+		return 0;
+
+	dst->lags = kcalloc(len, sizeof(*dst->lags), GFP_KERNEL);
+	if (!dst->lags)
+		return -ENOMEM;
+
+	dst->lags_len = len;
+	return 0;
+}
+
+static void dsa_tree_teardown_lags(struct dsa_switch_tree *dst)
+{
+	kfree(dst->lags);
+}
+
 static int dsa_tree_setup(struct dsa_switch_tree *dst)
 {
 	bool complete;
@@ -563,12 +900,18 @@ static int dsa_tree_setup(struct dsa_switch_tree *dst)
 	if (err)
 		goto teardown_switches;
 
+	err = dsa_tree_setup_lags(dst);
+	if (err)
+		goto teardown_master;
+
 	dst->setup = true;
 
 	pr_info("DSA: tree %d setup\n", dst->index);
 
 	return 0;
 
+teardown_master:
+	dsa_tree_teardown_master(dst);
 teardown_switches:
 	dsa_tree_teardown_switches(dst);
 teardown_default_cpu:
@@ -584,6 +927,8 @@ static void dsa_tree_teardown(struct dsa_switch_tree *dst)
 	if (!dst->setup)
 		return;
 
+	dsa_tree_teardown_lags(dst);
+
 	dsa_tree_teardown_master(dst);
 
 	dsa_tree_teardown_switches(dst);
@@ -600,6 +945,57 @@ static void dsa_tree_teardown(struct dsa_switch_tree *dst)
 	dst->setup = false;
 }
 
+/* Since the dsa/tagging sysfs device attribute is per master, the assumption
+ * is that all DSA switches within a tree share the same tagger, otherwise
+ * they would have formed disjoint trees (different "dsa,member" values).
+ */
+int dsa_tree_change_tag_proto(struct dsa_switch_tree *dst,
+			      struct net_device *master,
+			      const struct dsa_device_ops *tag_ops,
+			      const struct dsa_device_ops *old_tag_ops)
+{
+	struct dsa_notifier_tag_proto_info info;
+	struct dsa_port *dp;
+	int err = -EBUSY;
+
+	if (!rtnl_trylock())
+		return restart_syscall();
+
+	/* At the moment we don't allow changing the tag protocol under
+	 * traffic. The rtnl_mutex also happens to serialize concurrent
+	 * attempts to change the tagging protocol. If we ever lift the IFF_UP
+	 * restriction, there needs to be another mutex which serializes this.
+	 */
+	if (master->flags & IFF_UP)
+		goto out_unlock;
+
+	list_for_each_entry(dp, &dst->ports, list) {
+		if (!dsa_is_user_port(dp->ds, dp->index))
+			continue;
+
+		if (dp->slave->flags & IFF_UP)
+			goto out_unlock;
+	}
+
+	info.tag_ops = tag_ops;
+	err = dsa_tree_notify(dst, DSA_NOTIFIER_TAG_PROTO, &info);
+	if (err)
+		goto out_unwind_tagger;
+
+	dst->tag_ops = tag_ops;
+
+	rtnl_unlock();
+
+	return 0;
+
+out_unwind_tagger:
+	info.tag_ops = old_tag_ops;
+	dsa_tree_notify(dst, DSA_NOTIFIER_TAG_PROTO, &info);
+out_unlock:
+	rtnl_unlock();
+	return err;
+}
+
 static struct dsa_port *dsa_port_touch(struct dsa_switch *ds, int index)
 {
 	struct dsa_switch_tree *dst = ds->dst;
@@ -670,24 +1066,33 @@ static int dsa_port_parse_cpu(struct dsa_port *dp, struct net_device *master)
 {
 	struct dsa_switch *ds = dp->ds;
 	struct dsa_switch_tree *dst = ds->dst;
-	const struct dsa_device_ops *tag_ops;
 	enum dsa_tag_protocol tag_protocol;
 
 	tag_protocol = dsa_get_tag_protocol(dp, master);
-	tag_ops = dsa_tag_driver_get(tag_protocol);
-	if (IS_ERR(tag_ops)) {
-		if (PTR_ERR(tag_ops) == -ENOPROTOOPT)
-			return -EPROBE_DEFER;
-		dev_warn(ds->dev, "No tagger for this switch\n");
-		dp->master = NULL;
-		return PTR_ERR(tag_ops);
+	if (dst->tag_ops) {
+		if (dst->tag_ops->proto != tag_protocol) {
+			dev_err(ds->dev,
+				"A DSA switch tree can have only one tagging protocol\n");
+			return -EINVAL;
+		}
+		/* In the case of multiple CPU ports per switch, the tagging
+		 * protocol is still reference-counted only per switch tree, so
+		 * nothing to do here.
+		 */
+	} else {
+		dst->tag_ops = dsa_tag_driver_get(tag_protocol);
+		if (IS_ERR(dst->tag_ops)) {
+			if (PTR_ERR(dst->tag_ops) == -ENOPROTOOPT)
+				return -EPROBE_DEFER;
+			dev_warn(ds->dev, "No tagger for this switch\n");
+			dp->master = NULL;
+			return PTR_ERR(dst->tag_ops);
+		}
 	}
 
 	dp->master = master;
 	dp->type = DSA_PORT_TYPE_CPU;
-	dp->filter = tag_ops->filter;
-	dp->rcv = tag_ops->rcv;
-	dp->tag_ops = tag_ops;
+	dsa_port_set_tag_protocol(dp, dst->tag_ops);
 	dp->dst = dst;
 
 	return 0;
@@ -741,6 +1146,8 @@ static int dsa_switch_parse_ports_of(struct dsa_switch *ds,
 			goto out_put_node;
 
 		if (reg >= ds->num_ports) {
+			dev_err(ds->dev, "port %pOF index %u exceeds num_ports (%zu)\n",
+				port, reg, ds->num_ports);
 			err = -EINVAL;
 			goto out_put_node;
 		}