net/dsa/tag_8021q.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /* Copyright (c) 2019, Vladimir Oltean <olteanv@gmail.com>
  *
  * This module is not a complete tagger implementation. It only provides
  * primitives for taggers that rely on 802.1Q VLAN tags to use.
  */
 #include <linux/if_vlan.h>
 #include <linux/dsa/8021q.h>

 #include "port.h"
 #include "switch.h"
 #include "tag.h"
 #include "tag_8021q.h"

 /* Binary structure of the fake 12-bit VID field (when the TPID is
  * ETH_P_DSA_8021Q):
  *
  * | 11  | 10  |  9  |  8  |  7  |  6  |  5  |  4  |  3  |  2  |  1  |  0  |
  * +-----------+-----+-----------------+-----------+-----------------------+
  * |    RSV    | VBID|    SWITCH_ID    |   VBID    |          PORT         |
  * +-----------+-----+-----------------+-----------+-----------------------+
  *
  * RSV - VID[11:10]:
  *	Reserved. Must be set to 3 (0b11).
  *
  * SWITCH_ID - VID[8:6]:
  *	Index of switch within DSA tree. Must be between 0 and 7.
  *
  * VBID - { VID[9], VID[5:4] }:
  *	Virtual bridge ID. If between 1 and 7, packet targets the broadcast
  *	domain of a bridge. If transmitted as zero, packet targets a single
  *	port.
  *
  * PORT - VID[3:0]:
  *	Index of switch port. Must be between 0 and 15.
  */

 #define DSA_8021Q_RSV_VAL		3
 #define DSA_8021Q_RSV_SHIFT		10
 #define DSA_8021Q_RSV_MASK		GENMASK(11, 10)
 #define DSA_8021Q_RSV			((DSA_8021Q_RSV_VAL << DSA_8021Q_RSV_SHIFT) & \
 							       DSA_8021Q_RSV_MASK)

 #define DSA_8021Q_SWITCH_ID_SHIFT	6
 #define DSA_8021Q_SWITCH_ID_MASK	GENMASK(8, 6)
 #define DSA_8021Q_SWITCH_ID(x)		(((x) << DSA_8021Q_SWITCH_ID_SHIFT) & \
 						 DSA_8021Q_SWITCH_ID_MASK)

 #define DSA_8021Q_VBID_HI_SHIFT		9
 #define DSA_8021Q_VBID_HI_MASK		GENMASK(9, 9)
 #define DSA_8021Q_VBID_LO_SHIFT		4
 #define DSA_8021Q_VBID_LO_MASK		GENMASK(5, 4)
 #define DSA_8021Q_VBID_HI(x)		(((x) & GENMASK(2, 2)) >> 2)
 #define DSA_8021Q_VBID_LO(x)		((x) & GENMASK(1, 0))
 #define DSA_8021Q_VBID(x)		\
 		(((DSA_8021Q_VBID_LO(x) << DSA_8021Q_VBID_LO_SHIFT) & \
 		  DSA_8021Q_VBID_LO_MASK) | \
 		 ((DSA_8021Q_VBID_HI(x) << DSA_8021Q_VBID_HI_SHIFT) & \
 		  DSA_8021Q_VBID_HI_MASK))

 #define DSA_8021Q_PORT_SHIFT		0
 #define DSA_8021Q_PORT_MASK		GENMASK(3, 0)
 #define DSA_8021Q_PORT(x)		(((x) << DSA_8021Q_PORT_SHIFT) & \
 						 DSA_8021Q_PORT_MASK)

 struct dsa_tag_8021q_vlan {
 	struct list_head list;
 	int port;
 	u16 vid;
 	refcount_t refcount;
 };

 struct dsa_8021q_context {
 	struct dsa_switch *ds;
 	struct list_head vlans;
 	/* EtherType of RX VID, used for filtering on master interface */
 	__be16 proto;
 };

 u16 dsa_tag_8021q_bridge_vid(unsigned int bridge_num)
 {
 	/* The VBID value of 0 is reserved for precise TX, but it is also
 	 * reserved/invalid for the bridge_num, so all is well.
 	 */
 	return DSA_8021Q_RSV | DSA_8021Q_VBID(bridge_num);
 }
 EXPORT_SYMBOL_GPL(dsa_tag_8021q_bridge_vid);

 /* Returns the VID that will be installed as pvid for this switch port, sent as
  * tagged egress towards the CPU port and decoded by the rcv function.
  */
 u16 dsa_tag_8021q_standalone_vid(const struct dsa_port *dp)
 {
 	return DSA_8021Q_RSV | DSA_8021Q_SWITCH_ID(dp->ds->index) |
 	       DSA_8021Q_PORT(dp->index);
 }
 EXPORT_SYMBOL_GPL(dsa_tag_8021q_standalone_vid);

 /* Returns the decoded switch ID from the RX VID. */
 int dsa_8021q_rx_switch_id(u16 vid)
 {
 	return (vid & DSA_8021Q_SWITCH_ID_MASK) >> DSA_8021Q_SWITCH_ID_SHIFT;
 }
 EXPORT_SYMBOL_GPL(dsa_8021q_rx_switch_id);

 /* Returns the decoded port ID from the RX VID. */
 int dsa_8021q_rx_source_port(u16 vid)
 {
 	return (vid & DSA_8021Q_PORT_MASK) >> DSA_8021Q_PORT_SHIFT;
 }
 EXPORT_SYMBOL_GPL(dsa_8021q_rx_source_port);

 /* Returns the decoded VBID from the RX VID. */
 static int dsa_tag_8021q_rx_vbid(u16 vid)
 {
 	u16 vbid_hi = (vid & DSA_8021Q_VBID_HI_MASK) >> DSA_8021Q_VBID_HI_SHIFT;
 	u16 vbid_lo = (vid & DSA_8021Q_VBID_LO_MASK) >> DSA_8021Q_VBID_LO_SHIFT;

 	return (vbid_hi << 2) | vbid_lo;
 }

 bool vid_is_dsa_8021q(u16 vid)
 {
 	u16 rsv = (vid & DSA_8021Q_RSV_MASK) >> DSA_8021Q_RSV_SHIFT;

 	return rsv == DSA_8021Q_RSV_VAL;
 }
 EXPORT_SYMBOL_GPL(vid_is_dsa_8021q);

 static struct dsa_tag_8021q_vlan *
 dsa_tag_8021q_vlan_find(struct dsa_8021q_context *ctx, int port, u16 vid)
 {
 	struct dsa_tag_8021q_vlan *v;

 	list_for_each_entry(v, &ctx->vlans, list)
 		if (v->vid == vid && v->port == port)
 			return v;

 	return NULL;
 }

 static int dsa_port_do_tag_8021q_vlan_add(struct dsa_port *dp, u16 vid,
 					  u16 flags)
 {
 	struct dsa_8021q_context *ctx = dp->ds->tag_8021q_ctx;
 	struct dsa_switch *ds = dp->ds;
 	struct dsa_tag_8021q_vlan *v;
 	int port = dp->index;
 	int err;

 	/* No need to bother with refcounting for user ports */
 	if (!(dsa_port_is_cpu(dp) || dsa_port_is_dsa(dp)))
 		return ds->ops->tag_8021q_vlan_add(ds, port, vid, flags);

 	v = dsa_tag_8021q_vlan_find(ctx, port, vid);
 	if (v) {
 		refcount_inc(&v->refcount);
 		return 0;
 	}

 	v = kzalloc(sizeof(*v), GFP_KERNEL);
 	if (!v)
 		return -ENOMEM;

 	err = ds->ops->tag_8021q_vlan_add(ds, port, vid, flags);
 	if (err) {
 		kfree(v);
 		return err;
 	}

 	v->vid = vid;
 	v->port = port;
 	refcount_set(&v->refcount, 1);
 	list_add_tail(&v->list, &ctx->vlans);

 	return 0;
 }

 static int dsa_port_do_tag_8021q_vlan_del(struct dsa_port *dp, u16 vid)
 {
 	struct dsa_8021q_context *ctx = dp->ds->tag_8021q_ctx;
 	struct dsa_switch *ds = dp->ds;
 	struct dsa_tag_8021q_vlan *v;
 	int port = dp->index;
 	int err;

 	/* No need to bother with refcounting for user ports */
 	if (!(dsa_port_is_cpu(dp) || dsa_port_is_dsa(dp)))
 		return ds->ops->tag_8021q_vlan_del(ds, port, vid);

 	v = dsa_tag_8021q_vlan_find(ctx, port, vid);
 	if (!v)
 		return -ENOENT;

 	if (!refcount_dec_and_test(&v->refcount))
 		return 0;

 	err = ds->ops->tag_8021q_vlan_del(ds, port, vid);
 	if (err) {
 		refcount_inc(&v->refcount);
 		return err;
 	}

 	list_del(&v->list);
 	kfree(v);

 	return 0;
 }

 static bool
 dsa_port_tag_8021q_vlan_match(struct dsa_port *dp,
 			      struct dsa_notifier_tag_8021q_vlan_info *info)
 {
 	return dsa_port_is_dsa(dp) || dsa_port_is_cpu(dp) || dp == info->dp;
 }

 int dsa_switch_tag_8021q_vlan_add(struct dsa_switch *ds,
 				  struct dsa_notifier_tag_8021q_vlan_info *info)
 {
 	struct dsa_port *dp;
 	int err;

 	/* Since we use dsa_broadcast(), there might be other switches in other
 	 * trees which don't support tag_8021q, so don't return an error.
 	 * Or they might even support tag_8021q but have not registered yet to
 	 * use it (maybe they use another tagger currently).
 	 */
 	if (!ds->ops->tag_8021q_vlan_add || !ds->tag_8021q_ctx)
 		return 0;

 	dsa_switch_for_each_port(dp, ds) {
 		if (dsa_port_tag_8021q_vlan_match(dp, info)) {
 			u16 flags = 0;

 			if (dsa_port_is_user(dp))
 				flags |= BRIDGE_VLAN_INFO_UNTAGGED |
 					 BRIDGE_VLAN_INFO_PVID;

 			err = dsa_port_do_tag_8021q_vlan_add(dp, info->vid,
 							     flags);
 			if (err)
 				return err;
 		}
 	}

 	return 0;
 }

 int dsa_switch_tag_8021q_vlan_del(struct dsa_switch *ds,
 				  struct dsa_notifier_tag_8021q_vlan_info *info)
 {
 	struct dsa_port *dp;
 	int err;

 	if (!ds->ops->tag_8021q_vlan_del || !ds->tag_8021q_ctx)
 		return 0;

 	dsa_switch_for_each_port(dp, ds) {
 		if (dsa_port_tag_8021q_vlan_match(dp, info)) {
 			err = dsa_port_do_tag_8021q_vlan_del(dp, info->vid);
 			if (err)
 				return err;
 		}
 	}

 	return 0;
 }

 /* There are 2 ways of offloading tag_8021q VLANs.
  *
  * One is to use a hardware TCAM to push the port's standalone VLAN into the
  * frame when forwarding it to the CPU, as an egress modification rule on the
  * CPU port. This is preferable because it has no side effects for the
  * autonomous forwarding path, and accomplishes tag_8021q's primary goal of
  * identifying the source port of each packet based on VLAN ID.
  *
  * The other is to commit the tag_8021q VLAN as a PVID to the VLAN table, and
  * to configure the port as VLAN-unaware. This is less preferable because
  * unique source port identification can only be done for standalone ports;
  * under a VLAN-unaware bridge, all ports share the same tag_8021q VLAN as
  * PVID, and under a VLAN-aware bridge, packets received by software will not
  * have tag_8021q VLANs appended, just bridge VLANs.
  *
  * For tag_8021q implementations of the second type, this method is used to
  * replace the standalone tag_8021q VLAN of a port with the tag_8021q VLAN to
  * be used for VLAN-unaware bridging.
  */
 int dsa_tag_8021q_bridge_join(struct dsa_switch *ds, int port,
 			      struct dsa_bridge bridge)
 {
 	struct dsa_port *dp = dsa_to_port(ds, port);
 	u16 standalone_vid, bridge_vid;
 	int err;

 	/* Delete the standalone VLAN of the port and replace it with a
 	 * bridging VLAN
 	 */
 	standalone_vid = dsa_tag_8021q_standalone_vid(dp);
 	bridge_vid = dsa_tag_8021q_bridge_vid(bridge.num);

 	err = dsa_port_tag_8021q_vlan_add(dp, bridge_vid, true);
 	if (err)
 		return err;

 	dsa_port_tag_8021q_vlan_del(dp, standalone_vid, false);

 	return 0;
 }
 EXPORT_SYMBOL_GPL(dsa_tag_8021q_bridge_join);

 void dsa_tag_8021q_bridge_leave(struct dsa_switch *ds, int port,
 				struct dsa_bridge bridge)
 {
 	struct dsa_port *dp = dsa_to_port(ds, port);
 	u16 standalone_vid, bridge_vid;
 	int err;

 	/* Delete the bridging VLAN of the port and replace it with a
 	 * standalone VLAN
 	 */
 	standalone_vid = dsa_tag_8021q_standalone_vid(dp);
 	bridge_vid = dsa_tag_8021q_bridge_vid(bridge.num);

 	err = dsa_port_tag_8021q_vlan_add(dp, standalone_vid, false);
 	if (err) {
 		dev_err(ds->dev,
 			"Failed to delete tag_8021q standalone VLAN %d from port %d: %pe\n",
 			standalone_vid, port, ERR_PTR(err));
 	}

 	dsa_port_tag_8021q_vlan_del(dp, bridge_vid, true);
 }
 EXPORT_SYMBOL_GPL(dsa_tag_8021q_bridge_leave);

 /* Set up a port's standalone tag_8021q VLAN */
 static int dsa_tag_8021q_port_setup(struct dsa_switch *ds, int port)
 {
 	struct dsa_8021q_context *ctx = ds->tag_8021q_ctx;
 	struct dsa_port *dp = dsa_to_port(ds, port);
 	u16 vid = dsa_tag_8021q_standalone_vid(dp);
 	struct net_device *master;
 	int err;

 	/* The CPU port is implicitly configured by
 	 * configuring the front-panel ports
 	 */
 	if (!dsa_port_is_user(dp))
 		return 0;

 	master = dsa_port_to_master(dp);

 	err = dsa_port_tag_8021q_vlan_add(dp, vid, false);
 	if (err) {
 		dev_err(ds->dev,
 			"Failed to apply standalone VID %d to port %d: %pe\n",
 			vid, port, ERR_PTR(err));
 		return err;
 	}

 	/* Add the VLAN to the master's RX filter. */
 	vlan_vid_add(master, ctx->proto, vid);

 	return err;
 }

 static void dsa_tag_8021q_port_teardown(struct dsa_switch *ds, int port)
 {
 	struct dsa_8021q_context *ctx = ds->tag_8021q_ctx;
 	struct dsa_port *dp = dsa_to_port(ds, port);
 	u16 vid = dsa_tag_8021q_standalone_vid(dp);
 	struct net_device *master;

 	/* The CPU port is implicitly configured by
 	 * configuring the front-panel ports
 	 */
 	if (!dsa_port_is_user(dp))
 		return;

 	master = dsa_port_to_master(dp);

 	dsa_port_tag_8021q_vlan_del(dp, vid, false);

 	vlan_vid_del(master, ctx->proto, vid);
 }

 static int dsa_tag_8021q_setup(struct dsa_switch *ds)
 {
 	int err, port;

 	ASSERT_RTNL();

 	for (port = 0; port < ds->num_ports; port++) {
 		err = dsa_tag_8021q_port_setup(ds, port);
 		if (err < 0) {
 			dev_err(ds->dev,
 				"Failed to setup VLAN tagging for port %d: %pe\n",
 				port, ERR_PTR(err));
 			return err;
 		}
 	}

 	return 0;
 }

 static void dsa_tag_8021q_teardown(struct dsa_switch *ds)
 {
 	int port;

 	ASSERT_RTNL();

 	for (port = 0; port < ds->num_ports; port++)
 		dsa_tag_8021q_port_teardown(ds, port);
 }

 int dsa_tag_8021q_register(struct dsa_switch *ds, __be16 proto)
 {
 	struct dsa_8021q_context *ctx;
 	int err;

 	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
 	if (!ctx)
 		return -ENOMEM;

 	ctx->proto = proto;
 	ctx->ds = ds;

 	INIT_LIST_HEAD(&ctx->vlans);

 	ds->tag_8021q_ctx = ctx;

 	err = dsa_tag_8021q_setup(ds);
 	if (err)
 		goto err_free;

 	return 0;

 err_free:
 	kfree(ctx);
 	return err;
 }
 EXPORT_SYMBOL_GPL(dsa_tag_8021q_register);

 void dsa_tag_8021q_unregister(struct dsa_switch *ds)
 {
 	struct dsa_8021q_context *ctx = ds->tag_8021q_ctx;
 	struct dsa_tag_8021q_vlan *v, *n;

 	dsa_tag_8021q_teardown(ds);

 	list_for_each_entry_safe(v, n, &ctx->vlans, list) {
 		list_del(&v->list);
 		kfree(v);
 	}

 	ds->tag_8021q_ctx = NULL;

 	kfree(ctx);
 }
 EXPORT_SYMBOL_GPL(dsa_tag_8021q_unregister);

 struct sk_buff *dsa_8021q_xmit(struct sk_buff *skb, struct net_device *netdev,
 			       u16 tpid, u16 tci)
 {
 	/* skb->data points at the MAC header, which is fine
 	 * for vlan_insert_tag().
 	 */
 	return vlan_insert_tag(skb, htons(tpid), tci);
 }
 EXPORT_SYMBOL_GPL(dsa_8021q_xmit);

 struct net_device *dsa_tag_8021q_find_port_by_vbid(struct net_device *master,
 						   int vbid)
 {
 	struct dsa_port *cpu_dp = master->dsa_ptr;
 	struct dsa_switch_tree *dst = cpu_dp->dst;
 	struct dsa_port *dp;

 	if (WARN_ON(!vbid))
 		return NULL;

 	dsa_tree_for_each_user_port(dp, dst) {
 		if (!dp->bridge)
 			continue;

 		if (dp->stp_state != BR_STATE_LEARNING &&
 		    dp->stp_state != BR_STATE_FORWARDING)
 			continue;

 		if (dp->cpu_dp != cpu_dp)
 			continue;

 		if (dsa_port_bridge_num_get(dp) == vbid)
 			return dp->slave;
 	}

 	return NULL;
 }
 EXPORT_SYMBOL_GPL(dsa_tag_8021q_find_port_by_vbid);

 void dsa_8021q_rcv(struct sk_buff *skb, int *source_port, int *switch_id,
 		   int *vbid)
 {
 	u16 vid, tci;

 	if (skb_vlan_tag_present(skb)) {
 		tci = skb_vlan_tag_get(skb);
 		__vlan_hwaccel_clear_tag(skb);
 	} else {
 		skb_push_rcsum(skb, ETH_HLEN);
 		__skb_vlan_pop(skb, &tci);
 		skb_pull_rcsum(skb, ETH_HLEN);
 	}

 	vid = tci & VLAN_VID_MASK;

 	*source_port = dsa_8021q_rx_source_port(vid);
 	*switch_id = dsa_8021q_rx_switch_id(vid);

 	if (vbid)
 		*vbid = dsa_tag_8021q_rx_vbid(vid);

 	skb->priority = (tci & VLAN_PRIO_MASK) >> VLAN_PRIO_SHIFT;
 }
 EXPORT_SYMBOL_GPL(dsa_8021q_rcv);
	// SPDX-License-Identifier: GPL-2.0
	/* Copyright (c) 2019, Vladimir Oltean <olteanv@gmail.com>
	*
	* This module is not a complete tagger implementation. It only provides
	* primitives for taggers that rely on 802.1Q VLAN tags to use.
	*/
	#include <linux/if_vlan.h>
	#include <linux/dsa/8021q.h>

	#include "port.h"
	#include "switch.h"
	#include "tag.h"
	#include "tag_8021q.h"

	/* Binary structure of the fake 12-bit VID field (when the TPID is
	* ETH_P_DSA_8021Q):
	*
	* \| 11 \| 10 \| 9 \| 8 \| 7 \| 6 \| 5 \| 4 \| 3 \| 2 \| 1 \| 0 \|
	* +-----------+-----+-----------------+-----------+-----------------------+
	* \| RSV \| VBID\| SWITCH_ID \| VBID \| PORT \|
	* +-----------+-----+-----------------+-----------+-----------------------+
	*
	* RSV - VID[11:10]:
	* Reserved. Must be set to 3 (0b11).
	*
	* SWITCH_ID - VID[8:6]:
	* Index of switch within DSA tree. Must be between 0 and 7.
	*
	* VBID - { VID[9], VID[5:4] }:
	* Virtual bridge ID. If between 1 and 7, packet targets the broadcast
	* domain of a bridge. If transmitted as zero, packet targets a single
	* port.
	*
	* PORT - VID[3:0]:
	* Index of switch port. Must be between 0 and 15.
	*/

	#define DSA_8021Q_RSV_VAL 3
	#define DSA_8021Q_RSV_SHIFT 10
	#define DSA_8021Q_RSV_MASK GENMASK(11, 10)
	#define DSA_8021Q_RSV ((DSA_8021Q_RSV_VAL << DSA_8021Q_RSV_SHIFT) & \
	DSA_8021Q_RSV_MASK)

	#define DSA_8021Q_SWITCH_ID_SHIFT 6
	#define DSA_8021Q_SWITCH_ID_MASK GENMASK(8, 6)
	#define DSA_8021Q_SWITCH_ID(x) (((x) << DSA_8021Q_SWITCH_ID_SHIFT) & \
	DSA_8021Q_SWITCH_ID_MASK)

	#define DSA_8021Q_VBID_HI_SHIFT 9
	#define DSA_8021Q_VBID_HI_MASK GENMASK(9, 9)
	#define DSA_8021Q_VBID_LO_SHIFT 4
	#define DSA_8021Q_VBID_LO_MASK GENMASK(5, 4)
	#define DSA_8021Q_VBID_HI(x) (((x) & GENMASK(2, 2)) >> 2)
	#define DSA_8021Q_VBID_LO(x) ((x) & GENMASK(1, 0))
	#define DSA_8021Q_VBID(x) \
	(((DSA_8021Q_VBID_LO(x) << DSA_8021Q_VBID_LO_SHIFT) & \
	DSA_8021Q_VBID_LO_MASK) \| \
	((DSA_8021Q_VBID_HI(x) << DSA_8021Q_VBID_HI_SHIFT) & \
	DSA_8021Q_VBID_HI_MASK))

	#define DSA_8021Q_PORT_SHIFT 0
	#define DSA_8021Q_PORT_MASK GENMASK(3, 0)
	#define DSA_8021Q_PORT(x) (((x) << DSA_8021Q_PORT_SHIFT) & \
	DSA_8021Q_PORT_MASK)

	struct dsa_tag_8021q_vlan {
	struct list_head list;
	int port;
	u16 vid;
	refcount_t refcount;
	};

	struct dsa_8021q_context {
	struct dsa_switch *ds;
	struct list_head vlans;
	/* EtherType of RX VID, used for filtering on master interface */
	__be16 proto;
	};

	u16 dsa_tag_8021q_bridge_vid(unsigned int bridge_num)
	{
	/* The VBID value of 0 is reserved for precise TX, but it is also
	* reserved/invalid for the bridge_num, so all is well.
	*/
	return DSA_8021Q_RSV \| DSA_8021Q_VBID(bridge_num);
	}
	EXPORT_SYMBOL_GPL(dsa_tag_8021q_bridge_vid);

	/* Returns the VID that will be installed as pvid for this switch port, sent as
	* tagged egress towards the CPU port and decoded by the rcv function.
	*/
	u16 dsa_tag_8021q_standalone_vid(const struct dsa_port *dp)
	{
	return DSA_8021Q_RSV \| DSA_8021Q_SWITCH_ID(dp->ds->index) \|
	DSA_8021Q_PORT(dp->index);
	}
	EXPORT_SYMBOL_GPL(dsa_tag_8021q_standalone_vid);

	/* Returns the decoded switch ID from the RX VID. */
	int dsa_8021q_rx_switch_id(u16 vid)
	{
	return (vid & DSA_8021Q_SWITCH_ID_MASK) >> DSA_8021Q_SWITCH_ID_SHIFT;
	}
	EXPORT_SYMBOL_GPL(dsa_8021q_rx_switch_id);

	/* Returns the decoded port ID from the RX VID. */
	int dsa_8021q_rx_source_port(u16 vid)
	{
	return (vid & DSA_8021Q_PORT_MASK) >> DSA_8021Q_PORT_SHIFT;
	}
	EXPORT_SYMBOL_GPL(dsa_8021q_rx_source_port);

	/* Returns the decoded VBID from the RX VID. */
	static int dsa_tag_8021q_rx_vbid(u16 vid)
	{
	u16 vbid_hi = (vid & DSA_8021Q_VBID_HI_MASK) >> DSA_8021Q_VBID_HI_SHIFT;
	u16 vbid_lo = (vid & DSA_8021Q_VBID_LO_MASK) >> DSA_8021Q_VBID_LO_SHIFT;

	return (vbid_hi << 2) \| vbid_lo;
	}

	bool vid_is_dsa_8021q(u16 vid)
	{
	u16 rsv = (vid & DSA_8021Q_RSV_MASK) >> DSA_8021Q_RSV_SHIFT;

	return rsv == DSA_8021Q_RSV_VAL;
	}
	EXPORT_SYMBOL_GPL(vid_is_dsa_8021q);

	static struct dsa_tag_8021q_vlan *
	dsa_tag_8021q_vlan_find(struct dsa_8021q_context *ctx, int port, u16 vid)
	{
	struct dsa_tag_8021q_vlan *v;

	list_for_each_entry(v, &ctx->vlans, list)
	if (v->vid == vid && v->port == port)
	return v;

	return NULL;
	}

	static int dsa_port_do_tag_8021q_vlan_add(struct dsa_port *dp, u16 vid,
	u16 flags)
	{
	struct dsa_8021q_context *ctx = dp->ds->tag_8021q_ctx;
	struct dsa_switch *ds = dp->ds;
	struct dsa_tag_8021q_vlan *v;
	int port = dp->index;
	int err;

	/* No need to bother with refcounting for user ports */
	if (!(dsa_port_is_cpu(dp) \|\| dsa_port_is_dsa(dp)))
	return ds->ops->tag_8021q_vlan_add(ds, port, vid, flags);

	v = dsa_tag_8021q_vlan_find(ctx, port, vid);
	if (v) {
	refcount_inc(&v->refcount);
	return 0;
	}

	v = kzalloc(sizeof(*v), GFP_KERNEL);
	if (!v)
	return -ENOMEM;

	err = ds->ops->tag_8021q_vlan_add(ds, port, vid, flags);
	if (err) {
	kfree(v);
	return err;
	}

	v->vid = vid;
	v->port = port;
	refcount_set(&v->refcount, 1);
	list_add_tail(&v->list, &ctx->vlans);

	return 0;
	}

	static int dsa_port_do_tag_8021q_vlan_del(struct dsa_port *dp, u16 vid)
	{
	struct dsa_8021q_context *ctx = dp->ds->tag_8021q_ctx;
	struct dsa_switch *ds = dp->ds;
	struct dsa_tag_8021q_vlan *v;
	int port = dp->index;
	int err;

	/* No need to bother with refcounting for user ports */
	if (!(dsa_port_is_cpu(dp) \|\| dsa_port_is_dsa(dp)))
	return ds->ops->tag_8021q_vlan_del(ds, port, vid);

	v = dsa_tag_8021q_vlan_find(ctx, port, vid);
	if (!v)
	return -ENOENT;

	if (!refcount_dec_and_test(&v->refcount))
	return 0;

	err = ds->ops->tag_8021q_vlan_del(ds, port, vid);
	if (err) {
	refcount_inc(&v->refcount);
	return err;
	}

	list_del(&v->list);
	kfree(v);

	return 0;
	}

	static bool
	dsa_port_tag_8021q_vlan_match(struct dsa_port *dp,
	struct dsa_notifier_tag_8021q_vlan_info *info)
	{
	return dsa_port_is_dsa(dp) \|\| dsa_port_is_cpu(dp) \|\| dp == info->dp;
	}

	int dsa_switch_tag_8021q_vlan_add(struct dsa_switch *ds,
	struct dsa_notifier_tag_8021q_vlan_info *info)
	{
	struct dsa_port *dp;
	int err;

	/* Since we use dsa_broadcast(), there might be other switches in other
	* trees which don't support tag_8021q, so don't return an error.
	* Or they might even support tag_8021q but have not registered yet to
	* use it (maybe they use another tagger currently).
	*/
	if (!ds->ops->tag_8021q_vlan_add \|\| !ds->tag_8021q_ctx)
	return 0;

	dsa_switch_for_each_port(dp, ds) {
	if (dsa_port_tag_8021q_vlan_match(dp, info)) {
	u16 flags = 0;

	if (dsa_port_is_user(dp))
	flags \|= BRIDGE_VLAN_INFO_UNTAGGED \|
	BRIDGE_VLAN_INFO_PVID;

	err = dsa_port_do_tag_8021q_vlan_add(dp, info->vid,
	flags);
	if (err)
	return err;
	}
	}

	return 0;
	}

	int dsa_switch_tag_8021q_vlan_del(struct dsa_switch *ds,
	struct dsa_notifier_tag_8021q_vlan_info *info)
	{
	struct dsa_port *dp;
	int err;

	if (!ds->ops->tag_8021q_vlan_del \|\| !ds->tag_8021q_ctx)
	return 0;

	dsa_switch_for_each_port(dp, ds) {
	if (dsa_port_tag_8021q_vlan_match(dp, info)) {
	err = dsa_port_do_tag_8021q_vlan_del(dp, info->vid);
	if (err)
	return err;
	}
	}

	return 0;
	}

	/* There are 2 ways of offloading tag_8021q VLANs.
	*
	* One is to use a hardware TCAM to push the port's standalone VLAN into the
	* frame when forwarding it to the CPU, as an egress modification rule on the
	* CPU port. This is preferable because it has no side effects for the
	* autonomous forwarding path, and accomplishes tag_8021q's primary goal of
	* identifying the source port of each packet based on VLAN ID.
	*
	* The other is to commit the tag_8021q VLAN as a PVID to the VLAN table, and
	* to configure the port as VLAN-unaware. This is less preferable because
	* unique source port identification can only be done for standalone ports;
	* under a VLAN-unaware bridge, all ports share the same tag_8021q VLAN as
	* PVID, and under a VLAN-aware bridge, packets received by software will not
	* have tag_8021q VLANs appended, just bridge VLANs.
	*
	* For tag_8021q implementations of the second type, this method is used to
	* replace the standalone tag_8021q VLAN of a port with the tag_8021q VLAN to
	* be used for VLAN-unaware bridging.
	*/
	int dsa_tag_8021q_bridge_join(struct dsa_switch *ds, int port,
	struct dsa_bridge bridge)
	{
	struct dsa_port *dp = dsa_to_port(ds, port);
	u16 standalone_vid, bridge_vid;
	int err;

	/* Delete the standalone VLAN of the port and replace it with a
	* bridging VLAN
	*/
	standalone_vid = dsa_tag_8021q_standalone_vid(dp);
	bridge_vid = dsa_tag_8021q_bridge_vid(bridge.num);

	err = dsa_port_tag_8021q_vlan_add(dp, bridge_vid, true);
	if (err)
	return err;

	dsa_port_tag_8021q_vlan_del(dp, standalone_vid, false);

	return 0;
	}
	EXPORT_SYMBOL_GPL(dsa_tag_8021q_bridge_join);

	void dsa_tag_8021q_bridge_leave(struct dsa_switch *ds, int port,
	struct dsa_bridge bridge)
	{
	struct dsa_port *dp = dsa_to_port(ds, port);
	u16 standalone_vid, bridge_vid;
	int err;

	/* Delete the bridging VLAN of the port and replace it with a
	* standalone VLAN
	*/
	standalone_vid = dsa_tag_8021q_standalone_vid(dp);
	bridge_vid = dsa_tag_8021q_bridge_vid(bridge.num);

	err = dsa_port_tag_8021q_vlan_add(dp, standalone_vid, false);
	if (err) {
	dev_err(ds->dev,
	"Failed to delete tag_8021q standalone VLAN %d from port %d: %pe\n",
	standalone_vid, port, ERR_PTR(err));
	}

	dsa_port_tag_8021q_vlan_del(dp, bridge_vid, true);
	}
	EXPORT_SYMBOL_GPL(dsa_tag_8021q_bridge_leave);

	/* Set up a port's standalone tag_8021q VLAN */
	static int dsa_tag_8021q_port_setup(struct dsa_switch *ds, int port)
	{
	struct dsa_8021q_context *ctx = ds->tag_8021q_ctx;
	struct dsa_port *dp = dsa_to_port(ds, port);
	u16 vid = dsa_tag_8021q_standalone_vid(dp);
	struct net_device *master;
	int err;

	/* The CPU port is implicitly configured by
	* configuring the front-panel ports
	*/
	if (!dsa_port_is_user(dp))
	return 0;

	master = dsa_port_to_master(dp);

	err = dsa_port_tag_8021q_vlan_add(dp, vid, false);
	if (err) {
	dev_err(ds->dev,
	"Failed to apply standalone VID %d to port %d: %pe\n",
	vid, port, ERR_PTR(err));
	return err;
	}

	/* Add the VLAN to the master's RX filter. */
	vlan_vid_add(master, ctx->proto, vid);

	return err;
	}

	static void dsa_tag_8021q_port_teardown(struct dsa_switch *ds, int port)
	{
	struct dsa_8021q_context *ctx = ds->tag_8021q_ctx;
	struct dsa_port *dp = dsa_to_port(ds, port);
	u16 vid = dsa_tag_8021q_standalone_vid(dp);
	struct net_device *master;

	/* The CPU port is implicitly configured by
	* configuring the front-panel ports
	*/
	if (!dsa_port_is_user(dp))
	return;

	master = dsa_port_to_master(dp);

	dsa_port_tag_8021q_vlan_del(dp, vid, false);

	vlan_vid_del(master, ctx->proto, vid);
	}

	static int dsa_tag_8021q_setup(struct dsa_switch *ds)
	{
	int err, port;

	ASSERT_RTNL();

	for (port = 0; port < ds->num_ports; port++) {
	err = dsa_tag_8021q_port_setup(ds, port);
	if (err < 0) {
	dev_err(ds->dev,
	"Failed to setup VLAN tagging for port %d: %pe\n",
	port, ERR_PTR(err));
	return err;
	}
	}

	return 0;
	}

	static void dsa_tag_8021q_teardown(struct dsa_switch *ds)
	{
	int port;

	ASSERT_RTNL();

	for (port = 0; port < ds->num_ports; port++)
	dsa_tag_8021q_port_teardown(ds, port);
	}

	int dsa_tag_8021q_register(struct dsa_switch *ds, __be16 proto)
	{
	struct dsa_8021q_context *ctx;
	int err;

	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
	if (!ctx)
	return -ENOMEM;

	ctx->proto = proto;
	ctx->ds = ds;

	INIT_LIST_HEAD(&ctx->vlans);

	ds->tag_8021q_ctx = ctx;

	err = dsa_tag_8021q_setup(ds);
	if (err)
	goto err_free;

	return 0;

	err_free:
	kfree(ctx);
	return err;
	}
	EXPORT_SYMBOL_GPL(dsa_tag_8021q_register);

	void dsa_tag_8021q_unregister(struct dsa_switch *ds)
	{
	struct dsa_8021q_context *ctx = ds->tag_8021q_ctx;
	struct dsa_tag_8021q_vlan v, n;

	dsa_tag_8021q_teardown(ds);

	list_for_each_entry_safe(v, n, &ctx->vlans, list) {
	list_del(&v->list);
	kfree(v);
	}

	ds->tag_8021q_ctx = NULL;

	kfree(ctx);
	}
	EXPORT_SYMBOL_GPL(dsa_tag_8021q_unregister);

	struct sk_buff dsa_8021q_xmit(struct sk_buff skb, struct net_device *netdev,
	u16 tpid, u16 tci)
	{
	/* skb->data points at the MAC header, which is fine
	* for vlan_insert_tag().
	*/
	return vlan_insert_tag(skb, htons(tpid), tci);
	}
	EXPORT_SYMBOL_GPL(dsa_8021q_xmit);

	struct net_device dsa_tag_8021q_find_port_by_vbid(struct net_device master,
	int vbid)
	{
	struct dsa_port *cpu_dp = master->dsa_ptr;
	struct dsa_switch_tree *dst = cpu_dp->dst;
	struct dsa_port *dp;

	if (WARN_ON(!vbid))
	return NULL;

	dsa_tree_for_each_user_port(dp, dst) {
	if (!dp->bridge)
	continue;

	if (dp->stp_state != BR_STATE_LEARNING &&
	dp->stp_state != BR_STATE_FORWARDING)
	continue;

	if (dp->cpu_dp != cpu_dp)
	continue;

	if (dsa_port_bridge_num_get(dp) == vbid)
	return dp->slave;
	}

	return NULL;
	}
	EXPORT_SYMBOL_GPL(dsa_tag_8021q_find_port_by_vbid);

	void dsa_8021q_rcv(struct sk_buff skb, int source_port, int *switch_id,
	int *vbid)
	{
	u16 vid, tci;

	if (skb_vlan_tag_present(skb)) {
	tci = skb_vlan_tag_get(skb);
	__vlan_hwaccel_clear_tag(skb);
	} else {
	skb_push_rcsum(skb, ETH_HLEN);
	__skb_vlan_pop(skb, &tci);
	skb_pull_rcsum(skb, ETH_HLEN);
	}

	vid = tci & VLAN_VID_MASK;

	*source_port = dsa_8021q_rx_source_port(vid);
	*switch_id = dsa_8021q_rx_switch_id(vid);

	if (vbid)
	*vbid = dsa_tag_8021q_rx_vbid(vid);

	skb->priority = (tci & VLAN_PRIO_MASK) >> VLAN_PRIO_SHIFT;
	}
	EXPORT_SYMBOL_GPL(dsa_8021q_rcv);