tjh.dev
Linux kernel mirror (for testing)
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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 "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_RECV_SOURCE_PORT_MASK GENMASK(2, 0)
17#define MTK_HDR_XMIT_DP_BIT_MASK GENMASK(5, 0)
18#define MTK_HDR_XMIT_SA_DIS BIT(6)
19
20static struct sk_buff *mtk_tag_xmit(struct sk_buff *skb,
21 struct net_device *dev)
22{
23 struct dsa_port *dp = dsa_slave_to_port(dev);
24 u8 *mtk_tag;
25 bool is_vlan_skb = true;
26 unsigned char *dest = eth_hdr(skb)->h_dest;
27 bool is_multicast_skb = is_multicast_ether_addr(dest) &&
28 !is_broadcast_ether_addr(dest);
29
30 /* Build the special tag after the MAC Source Address. If VLAN header
31 * is present, it's required that VLAN header and special tag is
32 * being combined. Only in this way we can allow the switch can parse
33 * the both special and VLAN tag at the same time and then look up VLAN
34 * table with VID.
35 */
36 if (!skb_vlan_tagged(skb)) {
37 skb_push(skb, MTK_HDR_LEN);
38 memmove(skb->data, skb->data + MTK_HDR_LEN, 2 * ETH_ALEN);
39 is_vlan_skb = false;
40 }
41
42 mtk_tag = skb->data + 2 * ETH_ALEN;
43
44 /* Mark tag attribute on special tag insertion to notify hardware
45 * whether that's a combined special tag with 802.1Q header.
46 */
47 mtk_tag[0] = is_vlan_skb ? MTK_HDR_XMIT_TAGGED_TPID_8100 :
48 MTK_HDR_XMIT_UNTAGGED;
49 mtk_tag[1] = (1 << dp->index) & MTK_HDR_XMIT_DP_BIT_MASK;
50
51 /* Disable SA learning for multicast frames */
52 if (unlikely(is_multicast_skb))
53 mtk_tag[1] |= MTK_HDR_XMIT_SA_DIS;
54
55 /* Tag control information is kept for 802.1Q */
56 if (!is_vlan_skb) {
57 mtk_tag[2] = 0;
58 mtk_tag[3] = 0;
59 }
60
61 return skb;
62}
63
64static 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 unsigned char *dest = eth_hdr(skb)->h_dest;
71 bool is_multicast_skb = is_multicast_ether_addr(dest) &&
72 !is_broadcast_ether_addr(dest);
73
74 if (unlikely(!pskb_may_pull(skb, MTK_HDR_LEN)))
75 return NULL;
76
77 /* The MTK header is added by the switch between src addr
78 * and ethertype at this point, skb->data points to 2 bytes
79 * after src addr so header should be 2 bytes right before.
80 */
81 phdr = (__be16 *)(skb->data - 2);
82 hdr = ntohs(*phdr);
83
84 /* Remove MTK tag and recalculate checksum. */
85 skb_pull_rcsum(skb, MTK_HDR_LEN);
86
87 memmove(skb->data - ETH_HLEN,
88 skb->data - ETH_HLEN - MTK_HDR_LEN,
89 2 * ETH_ALEN);
90
91 /* Get source port information */
92 port = (hdr & MTK_HDR_RECV_SOURCE_PORT_MASK);
93
94 skb->dev = dsa_master_find_slave(dev, 0, port);
95 if (!skb->dev)
96 return NULL;
97
98 /* Only unicast or broadcast frames are offloaded */
99 if (likely(!is_multicast_skb))
100 skb->offload_fwd_mark = 1;
101
102 return skb;
103}
104
105static const struct dsa_device_ops mtk_netdev_ops = {
106 .name = "mtk",
107 .proto = DSA_TAG_PROTO_MTK,
108 .xmit = mtk_tag_xmit,
109 .rcv = mtk_tag_rcv,
110 .overhead = MTK_HDR_LEN,
111};
112
113MODULE_LICENSE("GPL");
114MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_MTK);
115
116module_dsa_tag_driver(mtk_netdev_ops);