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 "dsa_priv.h"
12
13 #define MTK_HDR_LEN 4
14 #define MTK_HDR_XMIT_UNTAGGED 0
15 #define MTK_HDR_XMIT_TAGGED_TPID_8100 1
16 #define MTK_HDR_XMIT_TAGGED_TPID_88A8 2
17 #define MTK_HDR_RECV_SOURCE_PORT_MASK GENMASK(2, 0)
18 #define MTK_HDR_XMIT_DP_BIT_MASK GENMASK(5, 0)
19 #define MTK_HDR_XMIT_SA_DIS BIT(6)
20
mtk_tag_xmit(struct sk_buff * skb,struct net_device * dev)21 static struct sk_buff *mtk_tag_xmit(struct sk_buff *skb,
22 struct net_device *dev)
23 {
24 struct dsa_port *dp = dsa_slave_to_port(dev);
25 u8 xmit_tpid;
26 u8 *mtk_tag;
27
28 /* Build the special tag after the MAC Source Address. If VLAN header
29 * is present, it's required that VLAN header and special tag is
30 * being combined. Only in this way we can allow the switch can parse
31 * the both special and VLAN tag at the same time and then look up VLAN
32 * table with VID.
33 */
34 switch (skb->protocol) {
35 case htons(ETH_P_8021Q):
36 xmit_tpid = MTK_HDR_XMIT_TAGGED_TPID_8100;
37 break;
38 case htons(ETH_P_8021AD):
39 xmit_tpid = MTK_HDR_XMIT_TAGGED_TPID_88A8;
40 break;
41 default:
42 xmit_tpid = MTK_HDR_XMIT_UNTAGGED;
43 skb_push(skb, MTK_HDR_LEN);
44 memmove(skb->data, skb->data + MTK_HDR_LEN, 2 * ETH_ALEN);
45 }
46
47 mtk_tag = skb->data + 2 * ETH_ALEN;
48
49 /* Mark tag attribute on special tag insertion to notify hardware
50 * whether that's a combined special tag with 802.1Q header.
51 */
52 mtk_tag[0] = xmit_tpid;
53 mtk_tag[1] = (1 << dp->index) & MTK_HDR_XMIT_DP_BIT_MASK;
54
55 /* Tag control information is kept for 802.1Q */
56 if (xmit_tpid == MTK_HDR_XMIT_UNTAGGED) {
57 mtk_tag[2] = 0;
58 mtk_tag[3] = 0;
59 }
60
61 return skb;
62 }
63
mtk_tag_rcv(struct sk_buff * skb,struct net_device * dev,struct packet_type * pt)64 static struct sk_buff *mtk_tag_rcv(struct sk_buff *skb, struct net_device *dev,
65 struct packet_type *pt)
66 {
67 u16 hdr;
68 int port;
69 __be16 *phdr;
70
71 if (unlikely(!pskb_may_pull(skb, MTK_HDR_LEN)))
72 return NULL;
73
74 /* The MTK header is added by the switch between src addr
75 * and ethertype at this point, skb->data points to 2 bytes
76 * after src addr so header should be 2 bytes right before.
77 */
78 phdr = (__be16 *)(skb->data - 2);
79 hdr = ntohs(*phdr);
80
81 /* Remove MTK tag and recalculate checksum. */
82 skb_pull_rcsum(skb, MTK_HDR_LEN);
83
84 memmove(skb->data - ETH_HLEN,
85 skb->data - ETH_HLEN - MTK_HDR_LEN,
86 2 * ETH_ALEN);
87
88 /* Get source port information */
89 port = (hdr & MTK_HDR_RECV_SOURCE_PORT_MASK);
90
91 skb->dev = dsa_master_find_slave(dev, 0, port);
92 if (!skb->dev)
93 return NULL;
94
95 skb->offload_fwd_mark = 1;
96
97 return skb;
98 }
99
100 static const struct dsa_device_ops mtk_netdev_ops = {
101 .name = "mtk",
102 .proto = DSA_TAG_PROTO_MTK,
103 .xmit = mtk_tag_xmit,
104 .rcv = mtk_tag_rcv,
105 .overhead = MTK_HDR_LEN,
106 };
107
108 MODULE_LICENSE("GPL");
109 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_MTK);
110
111 module_dsa_tag_driver(mtk_netdev_ops);
112