2 * Mediatek DSA Tag support
3 * Copyright (C) 2017 Landen Chao <landen.chao@mediatek.com>
4 * Sean Wang <sean.wang@mediatek.com>
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 and
7 * only version 2 as published by the Free Software Foundation.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
15 #include <linux/etherdevice.h>
16 #include <linux/if_vlan.h>
21 #define MTK_HDR_XMIT_UNTAGGED 0
22 #define MTK_HDR_XMIT_TAGGED_TPID_8100 1
23 #define MTK_HDR_XMIT_TAGGED_TPID_88A8 2
24 #define MTK_HDR_RECV_SOURCE_PORT_MASK GENMASK(2, 0)
25 #define MTK_HDR_XMIT_DP_BIT_MASK GENMASK(5, 0)
26 #define MTK_HDR_XMIT_SA_DIS BIT(6)
28 static struct sk_buff *mtk_tag_xmit(struct sk_buff *skb,
29 struct net_device *dev)
31 struct dsa_port *dp = dsa_slave_to_port(dev);
34 unsigned char *dest = eth_hdr(skb)->h_dest;
35 bool is_multicast_skb = is_multicast_ether_addr(dest) &&
36 !is_broadcast_ether_addr(dest);
38 /* Build the special tag after the MAC Source Address. If VLAN header
39 * is present, it's required that VLAN header and special tag is
40 * being combined. Only in this way we can allow the switch can parse
41 * the both special and VLAN tag at the same time and then look up VLAN
44 switch (skb->protocol) {
45 case htons(ETH_P_8021Q):
46 xmit_tpid = MTK_HDR_XMIT_TAGGED_TPID_8100;
48 case htons(ETH_P_8021AD):
49 xmit_tpid = MTK_HDR_XMIT_TAGGED_TPID_88A8;
52 if (skb_cow_head(skb, MTK_HDR_LEN) < 0)
55 xmit_tpid = MTK_HDR_XMIT_UNTAGGED;
56 skb_push(skb, MTK_HDR_LEN);
57 memmove(skb->data, skb->data + MTK_HDR_LEN, 2 * ETH_ALEN);
60 mtk_tag = skb->data + 2 * ETH_ALEN;
62 /* Mark tag attribute on special tag insertion to notify hardware
63 * whether that's a combined special tag with 802.1Q header.
65 mtk_tag[0] = xmit_tpid;
66 mtk_tag[1] = (1 << dp->index) & MTK_HDR_XMIT_DP_BIT_MASK;
68 /* Disable SA learning for multicast frames */
69 if (unlikely(is_multicast_skb))
70 mtk_tag[1] |= MTK_HDR_XMIT_SA_DIS;
72 /* Tag control information is kept for 802.1Q */
73 if (xmit_tpid == MTK_HDR_XMIT_UNTAGGED) {
81 static struct sk_buff *mtk_tag_rcv(struct sk_buff *skb, struct net_device *dev,
82 struct packet_type *pt)
86 unsigned char *dest = eth_hdr(skb)->h_dest;
87 bool is_multicast_skb = is_multicast_ether_addr(dest) &&
88 !is_broadcast_ether_addr(dest);
90 if (unlikely(!pskb_may_pull(skb, MTK_HDR_LEN)))
93 /* The MTK header is added by the switch between src addr
94 * and ethertype at this point, skb->data points to 2 bytes
95 * after src addr so header should be 2 bytes right before.
97 phdr = (__be16 *)(skb->data - 2);
100 /* Remove MTK tag and recalculate checksum. */
101 skb_pull_rcsum(skb, MTK_HDR_LEN);
103 memmove(skb->data - ETH_HLEN,
104 skb->data - ETH_HLEN - MTK_HDR_LEN,
107 /* Get source port information */
108 port = (hdr & MTK_HDR_RECV_SOURCE_PORT_MASK);
110 skb->dev = dsa_master_find_slave(dev, 0, port);
114 /* Only unicast or broadcast frames are offloaded */
115 if (likely(!is_multicast_skb))
116 skb->offload_fwd_mark = 1;
121 static int mtk_tag_flow_dissect(const struct sk_buff *skb, __be16 *proto,
125 *proto = ((__be16 *)skb->data)[1];
130 const struct dsa_device_ops mtk_netdev_ops = {
131 .xmit = mtk_tag_xmit,
133 .flow_dissect = mtk_tag_flow_dissect,