1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Mediatek DSA Tag support
4 * Copyright (C) 2017 Landen Chao <landen.chao@mediatek.com>
5 *		      Sean Wang <sean.wang@mediatek.com>
6 */
7
8#include <linux/etherdevice.h>
9#include <linux/if_vlan.h>
10
11#include "tag.h"
12
13#define MTK_NAME		"mtk"
14
15#define MTK_HDR_LEN		4
16#define MTK_HDR_XMIT_UNTAGGED		0
17#define MTK_HDR_XMIT_TAGGED_TPID_8100	1
18#define MTK_HDR_XMIT_TAGGED_TPID_88A8	2
19#define MTK_HDR_RECV_SOURCE_PORT_MASK	GENMASK(2, 0)
20#define MTK_HDR_XMIT_DP_BIT_MASK	GENMASK(5, 0)
21#define MTK_HDR_XMIT_SA_DIS		BIT(6)
22
23static struct sk_buff *mtk_tag_xmit(struct sk_buff *skb,
24				    struct net_device *dev)
25{
26	struct dsa_port *dp = dsa_user_to_port(dev);
27	u8 xmit_tpid;
28	u8 *mtk_tag;
29
30	skb_set_queue_mapping(skb, dp->index);
31
32	/* Build the special tag after the MAC Source Address. If VLAN header
33	 * is present, it's required that VLAN header and special tag is
34	 * being combined. Only in this way we can allow the switch can parse
35	 * the both special and VLAN tag at the same time and then look up VLAN
36	 * table with VID.
37	 */
38	switch (skb->protocol) {
39	case htons(ETH_P_8021Q):
40		xmit_tpid = MTK_HDR_XMIT_TAGGED_TPID_8100;
41		break;
42	case htons(ETH_P_8021AD):
43		xmit_tpid = MTK_HDR_XMIT_TAGGED_TPID_88A8;
44		break;
45	default:
46		xmit_tpid = MTK_HDR_XMIT_UNTAGGED;
47		skb_push(skb, MTK_HDR_LEN);
48		dsa_alloc_etype_header(skb, MTK_HDR_LEN);
49	}
50
51	mtk_tag = dsa_etype_header_pos_tx(skb);
52
53	/* Mark tag attribute on special tag insertion to notify hardware
54	 * whether that's a combined special tag with 802.1Q header.
55	 */
56	mtk_tag[0] = xmit_tpid;
57	mtk_tag[1] = (1 << dp->index) & MTK_HDR_XMIT_DP_BIT_MASK;
58
59	/* Tag control information is kept for 802.1Q */
60	if (xmit_tpid == MTK_HDR_XMIT_UNTAGGED) {
61		mtk_tag[2] = 0;
62		mtk_tag[3] = 0;
63	}
64
65	return skb;
66}
67
68static struct sk_buff *mtk_tag_rcv(struct sk_buff *skb, struct net_device *dev)
69{
70	u16 hdr;
71	int port;
72	__be16 *phdr;
73
74	if (unlikely(!pskb_may_pull(skb, MTK_HDR_LEN)))
75		return NULL;
76
77	phdr = dsa_etype_header_pos_rx(skb);
78	hdr = ntohs(*phdr);
79
80	/* Remove MTK tag and recalculate checksum. */
81	skb_pull_rcsum(skb, MTK_HDR_LEN);
82
83	dsa_strip_etype_header(skb, MTK_HDR_LEN);
84
85	/* Get source port information */
86	port = (hdr & MTK_HDR_RECV_SOURCE_PORT_MASK);
87
88	skb->dev = dsa_conduit_find_user(dev, 0, port);
89	if (!skb->dev)
90		return NULL;
91
92	dsa_default_offload_fwd_mark(skb);
93
94	return skb;
95}
96
97static const struct dsa_device_ops mtk_netdev_ops = {
98	.name		= MTK_NAME,
99	.proto		= DSA_TAG_PROTO_MTK,
100	.xmit		= mtk_tag_xmit,
101	.rcv		= mtk_tag_rcv,
102	.needed_headroom = MTK_HDR_LEN,
103};
104
105MODULE_DESCRIPTION("DSA tag driver for Mediatek switches");
106MODULE_LICENSE("GPL");
107MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_MTK, MTK_NAME);
108
109module_dsa_tag_driver(mtk_netdev_ops);
110