LXR linux/net/dsa/tag

   1/*
   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.
   8 *
   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.
  13 */
  14
  15#include <linux/etherdevice.h>
  16
  17#include "dsa_priv.h"
  18
  19#define MTK_HDR_LEN             4
  20#define MTK_HDR_RECV_SOURCE_PORT_MASK   GENMASK(2, 0)
  21#define MTK_HDR_XMIT_DP_BIT_MASK        GENMASK(5, 0)
  22
  23static struct sk_buff *mtk_tag_xmit(struct sk_buff *skb,
  24                                    struct net_device *dev)
  25{
  26        struct dsa_slave_priv *p = netdev_priv(dev);
  27        u8 *mtk_tag;
  28
  29        if (skb_cow_head(skb, MTK_HDR_LEN) < 0)
  30                return NULL;
  31
  32        skb_push(skb, MTK_HDR_LEN);
  33
  34        memmove(skb->data, skb->data + MTK_HDR_LEN, 2 * ETH_ALEN);
  35
  36        /* Build the tag after the MAC Source Address */
  37        mtk_tag = skb->data + 2 * ETH_ALEN;
  38        mtk_tag[0] = 0;
  39        mtk_tag[1] = (1 << p->dp->index) & MTK_HDR_XMIT_DP_BIT_MASK;
  40        mtk_tag[2] = 0;
  41        mtk_tag[3] = 0;
  42
  43        return skb;
  44}
  45
  46static struct sk_buff *mtk_tag_rcv(struct sk_buff *skb, struct net_device *dev,
  47                                   struct packet_type *pt)
  48{
  49        struct dsa_switch_tree *dst = dev->dsa_ptr;
  50        struct dsa_switch *ds;
  51        int port;
  52        __be16 *phdr, hdr;
  53
  54        if (unlikely(!pskb_may_pull(skb, MTK_HDR_LEN)))
  55                return NULL;
  56
  57        /* The MTK header is added by the switch between src addr
  58         * and ethertype at this point, skb->data points to 2 bytes
  59         * after src addr so header should be 2 bytes right before.
  60         */
  61        phdr = (__be16 *)(skb->data - 2);
  62        hdr = ntohs(*phdr);
  63
  64        /* Remove MTK tag and recalculate checksum. */
  65        skb_pull_rcsum(skb, MTK_HDR_LEN);
  66
  67        memmove(skb->data - ETH_HLEN,
  68                skb->data - ETH_HLEN - MTK_HDR_LEN,
  69                2 * ETH_ALEN);
  70
  71        /* This protocol doesn't support cascading multiple
  72         * switches so it's safe to assume the switch is first
  73         * in the tree.
  74         */
  75        ds = dst->ds[0];
  76        if (!ds)
  77                return NULL;
  78
  79        /* Get source port information */
  80        port = (hdr & MTK_HDR_RECV_SOURCE_PORT_MASK);
  81        if (!ds->ports[port].netdev)
  82                return NULL;
  83
  84        skb->dev = ds->ports[port].netdev;
  85
  86        return skb;
  87}
  88
  89static int mtk_tag_flow_dissect(const struct sk_buff *skb, __be16 *proto,
  90                                int *offset)
  91{
  92        *offset = 4;
  93        *proto = ((__be16 *)skb->data)[1];
  94
  95        return 0;
  96}
  97
  98const struct dsa_device_ops mtk_netdev_ops = {
  99        .xmit           = mtk_tag_xmit,
 100        .rcv            = mtk_tag_rcv,
 101        .flow_dissect   = mtk_tag_flow_dissect,
 102};
 103