net/dsa/tag_edsa.c

   1 /*
   2  * net/dsa/tag_edsa.c - Ethertype DSA tagging
   3  * Copyright (c) 2008 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
  16 #define DSA_HLEN        4
  17 #define EDSA_HLEN       8
  18
  19 int edsa_xmit(struct sk_buff *skb, struct net_device *dev)
  20 {
  21         struct dsa_slave_priv *p = netdev_priv(dev);
  22         u8 *edsa_header;
  23
  24         dev->stats.tx_packets++;
  25         dev->stats.tx_bytes += skb->len;
  26
  27         /*
  28          * Convert the outermost 802.1q tag to a DSA tag and prepend
  29          * a DSA ethertype field is the packet is tagged, or insert
  30          * a DSA ethertype plus DSA tag between the addresses and the
  31          * current ethertype field if the packet is untagged.
  32          */
  33         if (skb->protocol == htons(ETH_P_8021Q)) {
  34                 if (skb_cow_head(skb, DSA_HLEN) < 0)
  35                         goto out_free;
  36                 skb_push(skb, DSA_HLEN);
  37
  38                 memmove(skb->data, skb->data + DSA_HLEN, 2 * ETH_ALEN);
  39
  40                 /*
  41                  * Construct tagged FROM_CPU DSA tag from 802.1q tag.
  42                  */
  43                 edsa_header = skb->data + 2 * ETH_ALEN;
  44                 edsa_header[0] = (ETH_P_EDSA >> 8) & 0xff;
  45                 edsa_header[1] = ETH_P_EDSA & 0xff;
  46                 edsa_header[2] = 0x00;
  47                 edsa_header[3] = 0x00;
  48                 edsa_header[4] = 0x60;
  49                 edsa_header[5] = p->port << 3;
  50
  51                 /*
  52                  * Move CFI field from byte 6 to byte 5.
  53                  */
  54                 if (edsa_header[6] & 0x10) {
  55                         edsa_header[5] |= 0x01;
  56                         edsa_header[6] &= ~0x10;
  57                 }
  58         } else {
  59                 if (skb_cow_head(skb, EDSA_HLEN) < 0)
  60                         goto out_free;
  61                 skb_push(skb, EDSA_HLEN);
  62
  63                 memmove(skb->data, skb->data + EDSA_HLEN, 2 * ETH_ALEN);
  64
  65                 /*
  66                  * Construct untagged FROM_CPU DSA tag.
  67                  */
  68                 edsa_header = skb->data + 2 * ETH_ALEN;
  69                 edsa_header[0] = (ETH_P_EDSA >> 8) & 0xff;
  70                 edsa_header[1] = ETH_P_EDSA & 0xff;
  71                 edsa_header[2] = 0x00;
  72                 edsa_header[3] = 0x00;
  73                 edsa_header[4] = 0x40;
  74                 edsa_header[5] = p->port << 3;
  75                 edsa_header[6] = 0x00;
  76                 edsa_header[7] = 0x00;
  77         }
  78
  79         skb->protocol = htons(ETH_P_EDSA);
  80
  81         skb->dev = p->parent->master_netdev;
  82         dev_queue_xmit(skb);
  83
  84         return NETDEV_TX_OK;
  85
  86 out_free:
  87         kfree_skb(skb);
  88         return NETDEV_TX_OK;
  89 }
  90
  91 static int edsa_rcv(struct sk_buff *skb, struct net_device *dev,
  92                     struct packet_type *pt, struct net_device *orig_dev)
  93 {
  94         struct dsa_switch *ds = dev->dsa_ptr;
  95         u8 *edsa_header;
  96         int source_port;
  97
  98         if (unlikely(ds == NULL))
  99                 goto out_drop;
 100
 101         skb = skb_unshare(skb, GFP_ATOMIC);
 102         if (skb == NULL)
 103                 goto out;
 104
 105         if (unlikely(!pskb_may_pull(skb, EDSA_HLEN)))
 106                 goto out_drop;
 107
 108         /*
 109          * Skip the two null bytes after the ethertype.
 110          */
 111         edsa_header = skb->data + 2;
 112
 113         /*
 114          * Check that frame type is either TO_CPU or FORWARD, and
 115          * that the source device is zero.
 116          */
 117         if ((edsa_header[0] & 0xdf) != 0x00 && (edsa_header[0] & 0xdf) != 0xc0)
 118                 goto out_drop;
 119
 120         /*
 121          * Check that the source port is a registered DSA port.
 122          */
 123         source_port = (edsa_header[1] >> 3) & 0x1f;
 124         if (source_port >= DSA_MAX_PORTS || ds->ports[source_port] == NULL)
 125                 goto out_drop;
 126
 127         /*
 128          * If the 'tagged' bit is set, convert the DSA tag to a 802.1q
 129          * tag and delete the ethertype part.  If the 'tagged' bit is
 130          * clear, delete the ethertype and the DSA tag parts.
 131          */
 132         if (edsa_header[0] & 0x20) {
 133                 u8 new_header[4];
 134
 135                 /*
 136                  * Insert 802.1q ethertype and copy the VLAN-related
 137                  * fields, but clear the bit that will hold CFI (since
 138                  * DSA uses that bit location for another purpose).
 139                  */
 140                 new_header[0] = (ETH_P_8021Q >> 8) & 0xff;
 141                 new_header[1] = ETH_P_8021Q & 0xff;
 142                 new_header[2] = edsa_header[2] & ~0x10;
 143                 new_header[3] = edsa_header[3];
 144
 145                 /*
 146                  * Move CFI bit from its place in the DSA header to
 147                  * its 802.1q-designated place.
 148                  */
 149                 if (edsa_header[1] & 0x01)
 150                         new_header[2] |= 0x10;
 151
 152                 skb_pull_rcsum(skb, DSA_HLEN);
 153
 154                 /*
 155                  * Update packet checksum if skb is CHECKSUM_COMPLETE.
 156                  */
 157                 if (skb->ip_summed == CHECKSUM_COMPLETE) {
 158                         __wsum c = skb->csum;
 159                         c = csum_add(c, csum_partial(new_header + 2, 2, 0));
 160                         c = csum_sub(c, csum_partial(edsa_header + 2, 2, 0));
 161                         skb->csum = c;
 162                 }
 163
 164                 memcpy(edsa_header, new_header, DSA_HLEN);
 165
 166                 memmove(skb->data - ETH_HLEN,
 167                         skb->data - ETH_HLEN - DSA_HLEN,
 168                         2 * ETH_ALEN);
 169         } else {
 170                 /*
 171                  * Remove DSA tag and update checksum.
 172                  */
 173                 skb_pull_rcsum(skb, EDSA_HLEN);
 174                 memmove(skb->data - ETH_HLEN,
 175                         skb->data - ETH_HLEN - EDSA_HLEN,
 176                         2 * ETH_ALEN);
 177         }
 178
 179         skb->dev = ds->ports[source_port];
 180         skb_push(skb, ETH_HLEN);
 181         skb->protocol = eth_type_trans(skb, skb->dev);
 182
 183         skb->dev->last_rx = jiffies;
 184         skb->dev->stats.rx_packets++;
 185         skb->dev->stats.rx_bytes += skb->len;
 186
 187         netif_receive_skb(skb);
 188
 189         return 0;
 190
 191 out_drop:
 192         kfree_skb(skb);
 193 out:
 194         return 0;
 195 }
 196
 197 static struct packet_type edsa_packet_type = {
 198         .type   = __constant_htons(ETH_P_EDSA),
 199         .func   = edsa_rcv,
 200 };
 201
 202 static int __init edsa_init_module(void)
 203 {
 204         dev_add_pack(&edsa_packet_type);
 205         return 0;
 206 }
 207 module_init(edsa_init_module);
 208
 209 static void __exit edsa_cleanup_module(void)
 210 {
 211         dev_remove_pack(&edsa_packet_type);
 212 }
 213 module_exit(edsa_cleanup_module);