net/dsa/tag_trailer.c

   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
  16 static 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->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
  68 static 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
 110 out_drop:
 111         kfree_skb(skb);
 112 out:
 113         return 0;
 114 }
 115
 116 const struct dsa_device_ops trailer_netdev_ops = {
 117         .xmit   = trailer_xmit,
 118         .rcv    = trailer_rcv,
 119 };