LXR linux/net/dsa/tag

   1/*
   2 * net/dsa/tag_trailer.c - Trailer tag format handling
   3 * Copyright (c) 2008-2009 Marvell Semiconductor
   4 *
   5 * This program is free software; you can redistribute it and/or modify
   6 * it under the terms of the GNU General Public License as published by
   7 * the Free Software Foundation; either version 2 of the License, or
   8 * (at your option) any later version.
   9 */
  10
  11#include <linux/etherdevice.h>
  12#include <linux/list.h>
  13#include <linux/slab.h>
  14#include "dsa_priv.h"
  15
  16static netdev_tx_t trailer_xmit(struct sk_buff *skb, struct net_device *dev)
  17{
  18        struct dsa_slave_priv *p = netdev_priv(dev);
  19        struct sk_buff *nskb;
  20        int padlen;
  21        u8 *trailer;
  22
  23        dev->stats.tx_packets++;
  24        dev->stats.tx_bytes += skb->len;
  25
  26        /*
  27         * We have to make sure that the trailer ends up as the very
  28         * last 4 bytes of the packet.  This means that we have to pad
  29         * the packet to the minimum ethernet frame size, if necessary,
  30         * before adding the trailer.
  31         */
  32        padlen = 0;
  33        if (skb->len < 60)
  34                padlen = 60 - skb->len;
  35
  36        nskb = alloc_skb(NET_IP_ALIGN + skb->len + padlen + 4, GFP_ATOMIC);
  37        if (nskb == NULL) {
  38                kfree_skb(skb);
  39                return NETDEV_TX_OK;
  40        }
  41        skb_reserve(nskb, NET_IP_ALIGN);
  42
  43        skb_reset_mac_header(nskb);
  44        skb_set_network_header(nskb, skb_network_header(skb) - skb->head);
  45        skb_set_transport_header(nskb, skb_transport_header(skb) - skb->head);
  46        skb_copy_and_csum_dev(skb, skb_put(nskb, skb->len));
  47        kfree_skb(skb);
  48
  49        if (padlen) {
  50                u8 *pad = skb_put(nskb, padlen);
  51                memset(pad, 0, padlen);
  52        }
  53
  54        trailer = skb_put(nskb, 4);
  55        trailer[0] = 0x80;
  56        trailer[1] = 1 << p->port;
  57        trailer[2] = 0x10;
  58        trailer[3] = 0x00;
  59
  60        nskb->dev = p->parent->dst->master_netdev;
  61        dev_queue_xmit(nskb);
  62
  63        return NETDEV_TX_OK;
  64}
  65
  66static int trailer_rcv(struct sk_buff *skb, struct net_device *dev,
  67                       struct packet_type *pt, struct net_device *orig_dev)
  68{
  69        struct dsa_switch_tree *dst = dev->dsa_ptr;
  70        struct dsa_switch *ds;
  71        u8 *trailer;
  72        int source_port;
  73
  74        if (unlikely(dst == NULL))
  75                goto out_drop;
  76        ds = dst->ds[0];
  77
  78        skb = skb_unshare(skb, GFP_ATOMIC);
  79        if (skb == NULL)
  80                goto out;
  81
  82        if (skb_linearize(skb))
  83                goto out_drop;
  84
  85        trailer = skb_tail_pointer(skb) - 4;
  86        if (trailer[0] != 0x80 || (trailer[1] & 0xf8) != 0x00 ||
  87            (trailer[3] & 0xef) != 0x00 || trailer[3] != 0x00)
  88                goto out_drop;
  89
  90        source_port = trailer[1] & 7;
  91        if (source_port >= DSA_MAX_PORTS || ds->ports[source_port] == NULL)
  92                goto out_drop;
  93
  94        pskb_trim_rcsum(skb, skb->len - 4);
  95
  96        skb->dev = ds->ports[source_port];
  97        skb_push(skb, ETH_HLEN);
  98        skb->pkt_type = PACKET_HOST;
  99        skb->protocol = eth_type_trans(skb, skb->dev);
 100
 101        skb->dev->stats.rx_packets++;
 102        skb->dev->stats.rx_bytes += skb->len;
 103
 104        netif_receive_skb(skb);
 105
 106        return 0;
 107
 108out_drop:
 109        kfree_skb(skb);
 110out:
 111        return 0;
 112}
 113
 114const struct dsa_device_ops trailer_netdev_ops = {
 115        .xmit   = trailer_xmit,
 116        .rcv    = trailer_rcv,
 117};
 118