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
mtk_tag_xmit(struct sk_buff * skb,struct net_device * dev)23 static 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
mtk_tag_rcv(struct sk_buff * skb,struct net_device * dev)68 static 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
97 static 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
105 MODULE_DESCRIPTION("DSA tag driver for Mediatek switches");
106 MODULE_LICENSE("GPL");
107 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_MTK, MTK_NAME);
108
109 module_dsa_tag_driver(mtk_netdev_ops);
110