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/netdevice.h>
  14#include "dsa_priv.h"
  15
  16netdev_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->protocol = htons(ETH_P_TRAILER);
  61
  62        nskb->dev = p->parent->dst->master_netdev;
  63        dev_queue_xmit(nskb);
  64
  65        return NETDEV_TX_OK;
  66}
  67
  68static int trailer_rcv(struct sk_buff *skb, struct net_device *dev,
  69                       struct packet_type *pt, struct net_device *orig_dev)
  70{
  71        struct dsa_switch_tree *dst = dev->dsa_ptr;
  72        struct dsa_switch *ds;
  73        u8 *trailer;
  74        int source_port;
  75
  76        if (unlikely(dst == NULL))
  77                goto out_drop;
  78        ds = dst->ds[0];
  79
  80        skb = skb_unshare(skb, GFP_ATOMIC);
  81        if (skb == NULL)
  82                goto out;
  83
  84        if (skb_linearize(skb))
  85                goto out_drop;
  86
  87        trailer = skb_tail_pointer(skb) - 4;
  88        if (trailer[0] != 0x80 || (trailer[1] & 0xf8) != 0x00 ||
  89            (trailer[3] & 0xef) != 0x00 || trailer[3] != 0x00)
  90                goto out_drop;
  91
  92        source_port = trailer[1] & 7;
  93        if (source_port >= DSA_MAX_PORTS || ds->ports[source_port] == NULL)
  94                goto out_drop;
  95
  96        pskb_trim_rcsum(skb, skb->len - 4);
  97
  98        skb->dev = ds->ports[source_port];
  99        skb_push(skb, ETH_HLEN);
 100        skb->pkt_type = PACKET_HOST;
 101        skb->protocol = eth_type_trans(skb, skb->dev);
 102
 103        skb->dev->stats.rx_packets++;
 104        skb->dev->stats.rx_bytes += skb->len;
 105
 106        netif_receive_skb(skb);
 107
 108        return 0;
 109
 110out_drop:
 111        kfree_skb(skb);
 112out:
 113        return 0;
 114}
 115
 116static struct packet_type trailer_packet_type __read_mostly = {
 117        .type   = cpu_to_be16(ETH_P_TRAILER),
 118        .func   = trailer_rcv,
 119};
 120
 121static int __init trailer_init_module(void)
 122{
 123        dev_add_pack(&trailer_packet_type);
 124        return 0;
 125}
 126module_init(trailer_init_module);
 127
 128static void __exit trailer_cleanup_module(void)
 129{
 130        dev_remove_pack(&trailer_packet_type);
 131}
 132module_exit(trailer_cleanup_module);
 133