1 // SPDX-License-Identifier: GPL-2.0
3 * Mediatek DSA Tag support
4 * Copyright (C) 2017 Landen Chao <landen.chao@mediatek.com>
5 * Sean Wang <sean.wang@mediatek.com>
8 #include <linux/etherdevice.h>
9 #include <linux/if_vlan.h>
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)
21 static struct sk_buff *mtk_tag_xmit(struct sk_buff *skb,
22 struct net_device *dev)
24 struct dsa_port *dp = dsa_slave_to_port(dev);
27 unsigned char *dest = eth_hdr(skb)->h_dest;
28 bool is_multicast_skb = is_multicast_ether_addr(dest) &&
29 !is_broadcast_ether_addr(dest);
31 /* Build the special tag after the MAC Source Address. If VLAN header
32 * is present, it's required that VLAN header and special tag is
33 * being combined. Only in this way we can allow the switch can parse
34 * the both special and VLAN tag at the same time and then look up VLAN
37 switch (skb->protocol) {
38 case htons(ETH_P_8021Q):
39 xmit_tpid = MTK_HDR_XMIT_TAGGED_TPID_8100;
41 case htons(ETH_P_8021AD):
42 xmit_tpid = MTK_HDR_XMIT_TAGGED_TPID_88A8;
45 if (skb_cow_head(skb, MTK_HDR_LEN) < 0)
48 xmit_tpid = MTK_HDR_XMIT_UNTAGGED;
49 skb_push(skb, MTK_HDR_LEN);
50 memmove(skb->data, skb->data + MTK_HDR_LEN, 2 * ETH_ALEN);
53 mtk_tag = skb->data + 2 * ETH_ALEN;
55 /* Mark tag attribute on special tag insertion to notify hardware
56 * whether that's a combined special tag with 802.1Q header.
58 mtk_tag[0] = xmit_tpid;
59 mtk_tag[1] = (1 << dp->index) & MTK_HDR_XMIT_DP_BIT_MASK;
61 /* Disable SA learning for multicast frames */
62 if (unlikely(is_multicast_skb))
63 mtk_tag[1] |= MTK_HDR_XMIT_SA_DIS;
65 /* Tag control information is kept for 802.1Q */
66 if (xmit_tpid == MTK_HDR_XMIT_UNTAGGED) {
74 static struct sk_buff *mtk_tag_rcv(struct sk_buff *skb, struct net_device *dev,
75 struct packet_type *pt)
79 unsigned char *dest = eth_hdr(skb)->h_dest;
80 bool is_multicast_skb = is_multicast_ether_addr(dest) &&
81 !is_broadcast_ether_addr(dest);
83 if (unlikely(!pskb_may_pull(skb, MTK_HDR_LEN)))
86 /* The MTK header is added by the switch between src addr
87 * and ethertype at this point, skb->data points to 2 bytes
88 * after src addr so header should be 2 bytes right before.
90 phdr = (__be16 *)(skb->data - 2);
93 /* Remove MTK tag and recalculate checksum. */
94 skb_pull_rcsum(skb, MTK_HDR_LEN);
96 memmove(skb->data - ETH_HLEN,
97 skb->data - ETH_HLEN - MTK_HDR_LEN,
100 /* Get source port information */
101 port = (hdr & MTK_HDR_RECV_SOURCE_PORT_MASK);
103 skb->dev = dsa_master_find_slave(dev, 0, port);
107 /* Only unicast or broadcast frames are offloaded */
108 if (likely(!is_multicast_skb))
109 skb->offload_fwd_mark = 1;
114 static int mtk_tag_flow_dissect(const struct sk_buff *skb, __be16 *proto,
118 *proto = ((__be16 *)skb->data)[1];
123 static const struct dsa_device_ops mtk_netdev_ops = {
125 .proto = DSA_TAG_PROTO_MTK,
126 .xmit = mtk_tag_xmit,
128 .flow_dissect = mtk_tag_flow_dissect,
129 .overhead = MTK_HDR_LEN,
132 MODULE_LICENSE("GPL");
133 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_MTK);
135 module_dsa_tag_driver(mtk_netdev_ops);