LXR linux/net/dsa/tag

   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
  21static 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
  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
  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
 100static 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        .needed_headroom = MTK_HDR_LEN,
 106};
 107
 108MODULE_LICENSE("GPL");
 109MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_MTK);
 110
 111module_dsa_tag_driver(mtk_netdev_ops);
 112