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                dsa_alloc_etype_header(skb, MTK_HDR_LEN);
  45        }
  46
  47        mtk_tag = dsa_etype_header_pos_tx(skb);
  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{
  66        u16 hdr;
  67        int port;
  68        __be16 *phdr;
  69
  70        if (unlikely(!pskb_may_pull(skb, MTK_HDR_LEN)))
  71                return NULL;
  72
  73        phdr = dsa_etype_header_pos_rx(skb);
  74        hdr = ntohs(*phdr);
  75
  76        /* Remove MTK tag and recalculate checksum. */
  77        skb_pull_rcsum(skb, MTK_HDR_LEN);
  78
  79        dsa_strip_etype_header(skb, MTK_HDR_LEN);
  80
  81        /* Get source port information */
  82        port = (hdr & MTK_HDR_RECV_SOURCE_PORT_MASK);
  83
  84        skb->dev = dsa_master_find_slave(dev, 0, port);
  85        if (!skb->dev)
  86                return NULL;
  87
  88        dsa_default_offload_fwd_mark(skb);
  89
  90        return skb;
  91}
  92
  93static const struct dsa_device_ops mtk_netdev_ops = {
  94        .name           = "mtk",
  95        .proto          = DSA_TAG_PROTO_MTK,
  96        .xmit           = mtk_tag_xmit,
  97        .rcv            = mtk_tag_rcv,
  98        .needed_headroom = MTK_HDR_LEN,
  99};
 100
 101MODULE_LICENSE("GPL");
 102MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_MTK);
 103
 104module_dsa_tag_driver(mtk_netdev_ops);
 105