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linux
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] = FIELD_PREP(MTK_HDR_XMIT_DP_BIT_MASK,
58 dsa_xmit_port_mask(skb, dev));
59
60 /* Tag control information is kept for 802.1Q */
61 if (xmit_tpid == MTK_HDR_XMIT_UNTAGGED) {
62 mtk_tag[2] = 0;
63 mtk_tag[3] = 0;
64 }
65
66 return skb;
67}
68
69static struct sk_buff *mtk_tag_rcv(struct sk_buff *skb, struct net_device *dev)
70{
71 u16 hdr;
72 int port;
73 __be16 *phdr;
74
75 if (unlikely(!pskb_may_pull(skb, MTK_HDR_LEN)))
76 return NULL;
77
78 phdr = dsa_etype_header_pos_rx(skb);
79 hdr = ntohs(*phdr);
80
81 /* Remove MTK tag and recalculate checksum. */
82 skb_pull_rcsum(skb, MTK_HDR_LEN);
83
84 dsa_strip_etype_header(skb, MTK_HDR_LEN);
85
86 /* Get source port information */
87 port = (hdr & MTK_HDR_RECV_SOURCE_PORT_MASK);
88
89 skb->dev = dsa_conduit_find_user(dev, 0, port);
90 if (!skb->dev)
91 return NULL;
92
93 dsa_default_offload_fwd_mark(skb);
94
95 return skb;
96}
97
98static const struct dsa_device_ops mtk_netdev_ops = {
99 .name = MTK_NAME,
100 .proto = DSA_TAG_PROTO_MTK,
101 .xmit = mtk_tag_xmit,
102 .rcv = mtk_tag_rcv,
103 .needed_headroom = MTK_HDR_LEN,
104};
105
106MODULE_DESCRIPTION("DSA tag driver for Mediatek switches");
107MODULE_LICENSE("GPL");
108MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_MTK, MTK_NAME);
109
110module_dsa_tag_driver(mtk_netdev_ops);