github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-09-13 15:40:03 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

net: dsa: initial MT7628 tagging driver

Browse Source 
Add support for the MT7628 embedded switch's tag.

The MT7628 tag is merged with the VLAN TPID field when a VLAN is
appended by the switch hardware. It is not installed if the VLAN tag is
already there on ingress. Due to this hardware quirk the tag cannot be
trusted for port 0 if we don't know that the VLAN was added by the
hardware. As a workaround for this the switch is configured to always
append the port PVID tag even if the incoming packet is already tagged.
The tagging driver can then trust that the tag is always accurate and
the whole VLAN tag can be removed on ingress as it's only metadata for
the tagger.

On egress the MT7628 tag allows precise TX, but the correct VLAN tag
from tag_8021q is still appended or the switch will not forward the
packet.

Signed-off-by: Joris Vaisvila <joey@tinyisr.com>
Link: https://patch.msgid.link/20260813190241.789323-4-joey@tinyisr.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Joris Vaisvila 2026-08-13 22:02:40 +03:00 committed by Paolo Abeni
parent c9c235775b
commit 44204fd425
4 changed files with 102 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/net/dsa.h
View File

@ -60,6 +60,7 @@ struct tc_action;
#define DSA_TAG_PROTO_MXL862_VALUE 32
#define DSA_TAG_PROTO_NETC_VALUE 33
#define DSA_TAG_PROTO_KSZ8463_VALUE 34
#define DSA_TAG_PROTO_MT7628_VALUE 35
enum dsa_tag_protocol {
DSA_TAG_PROTO_NONE = DSA_TAG_PROTO_NONE_VALUE,
@ -97,6 +98,7 @@ enum dsa_tag_protocol {
DSA_TAG_PROTO_MXL862 = DSA_TAG_PROTO_MXL862_VALUE,
DSA_TAG_PROTO_NETC = DSA_TAG_PROTO_NETC_VALUE,
DSA_TAG_PROTO_KSZ8463 = DSA_TAG_PROTO_KSZ8463_VALUE,
DSA_TAG_PROTO_MT7628 = DSA_TAG_PROTO_MT7628_VALUE,
};
struct dsa_switch;

6
net/dsa/Kconfig
View File

@ -98,6 +98,12 @@ config NET_DSA_TAG_EDSA
Say Y or M if you want to enable support for tagging frames for the
Marvell switches which use EtherType DSA headers.
config NET_DSA_TAG_MT7628
tristate "Tag driver for the MT7628 embedded switch"
help
Say Y or M if you want to enable support for tagging frames for the
switch embedded in the MT7628 SoC.
config NET_DSA_TAG_MTK
tristate "Tag driver for Mediatek switches"
help

1
net/dsa/Makefile
View File

@ -27,6 +27,7 @@ obj-$(CONFIG_NET_DSA_TAG_GSWIP) += tag_gswip.o
obj-$(CONFIG_NET_DSA_TAG_HELLCREEK) += tag_hellcreek.o
obj-$(CONFIG_NET_DSA_TAG_KSZ) += tag_ksz.o
obj-$(CONFIG_NET_DSA_TAG_LAN9303) += tag_lan9303.o
obj-$(CONFIG_NET_DSA_TAG_MT7628) += tag_mt7628.o
obj-$(CONFIG_NET_DSA_TAG_MTK) += tag_mtk.o
obj-$(CONFIG_NET_DSA_TAG_MXL_862XX) += tag_mxl862xx.o
obj-$(CONFIG_NET_DSA_TAG_MXL_GSW1XX) += tag_mxl-gsw1xx.o

93
net/dsa/tag_mt7628.c Normal file
View File

@ -0,0 +1,93 @@
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2026, Joris Vaisvila <joey@tinyisr.com>
* MT7628 switch tag support
*/
#include <linux/etherdevice.h>
#include <linux/dsa/8021q.h>
#include <net/dsa.h>
#include "tag.h"
/*
* The MT7628 tag is encoded in the VLAN TPID field.
* On TX the lower 6 bits encode the destination port bitmask.
* On RX the lower 3 bits encode the source port number.
*
* The switch hardware will not modify the TPID of an incoming packet if it is
* already VLAN tagged. To work around this the switch is configured to always
* append a tag_8021q standalone VLAN tag for each port. That means we can
* safely strip the outer VLAN tag after parsing it.
*
* A VLAN tag is constructed on egress to target the standalone VLAN and
* destination port.
*/
#define MT7628_TAG_NAME "mt7628"
#define MT7628_TAG_TX_PORT GENMASK(5, 0)
#define MT7628_TAG_RX_PORT GENMASK(2, 0)
#define MT7628_TAG_LEN 4
static struct sk_buff *mt7628_tag_xmit(struct sk_buff *skb,
struct net_device *dev)
{
struct dsa_port *dp;
u16 xmit_vlan;
__be16 *tag;
dp = dsa_user_to_port(dev);
xmit_vlan = dsa_tag_8021q_standalone_vid(dp);
skb_push(skb, MT7628_TAG_LEN);
dsa_alloc_etype_header(skb, MT7628_TAG_LEN);
tag = dsa_etype_header_pos_tx(skb);
tag[0] = htons(ETH_P_8021Q |
FIELD_PREP(MT7628_TAG_TX_PORT,
dsa_xmit_port_mask(skb, dev)));
tag[1] = htons(xmit_vlan);
return skb;
}
static struct sk_buff *mt7628_tag_rcv(struct sk_buff *skb,
struct net_device *dev)
{
__be16 *phdr;
if (unlikely(!pskb_may_pull(skb, MT7628_TAG_LEN))) {
kfree_skb(skb);
return NULL;
}
phdr = dsa_etype_header_pos_rx(skb);
skb->dev =
dsa_conduit_find_user(dev, 0,
FIELD_GET(MT7628_TAG_RX_PORT, ntohs(*phdr)));
if (!skb->dev) {
kfree_skb(skb);
return NULL;
}
skb_pull_rcsum(skb, MT7628_TAG_LEN);
dsa_strip_etype_header(skb, MT7628_TAG_LEN);
dsa_default_offload_fwd_mark(skb);
return skb;
}
static const struct dsa_device_ops mt7628_tag_ops = {
.name = MT7628_TAG_NAME,
.proto = DSA_TAG_PROTO_MT7628,
.xmit = mt7628_tag_xmit,
.rcv = mt7628_tag_rcv,
.needed_headroom = MT7628_TAG_LEN,
};
module_dsa_tag_driver(mt7628_tag_ops);
MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_MT7628, MT7628_TAG_NAME);
MODULE_DESCRIPTION("DSA tag driver for MT7628 switch");
MODULE_LICENSE("GPL");