net/dsa/tag_dsa.c

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