net/dsa/tag_edsa.c

   1 /*
   2  * net/dsa/tag_edsa.c - Ethertype DSA tagging
   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
  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 | p->parent->index;
  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 | p->parent->index;
  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->dst->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_tree *dst = dev->dsa_ptr;
  95         struct dsa_switch *ds;
  96         u8 *edsa_header;
  97         int source_device;
  98         int source_port;
  99
 100         if (unlikely(dst == NULL))
 101                 goto out_drop;
 102
 103         skb = skb_unshare(skb, GFP_ATOMIC);
 104         if (skb == NULL)
 105                 goto out;
 106
 107         if (unlikely(!pskb_may_pull(skb, EDSA_HLEN)))
 108                 goto out_drop;
 109
 110         /*
 111          * Skip the two null bytes after the ethertype.
 112          */
 113         edsa_header = skb->data + 2;
 114
 115         /*
 116          * Check that frame type is either TO_CPU or FORWARD.
 117          */
 118         if ((edsa_header[0] & 0xc0) != 0x00 && (edsa_header[0] & 0xc0) != 0xc0)
 119                 goto out_drop;
 120
 121         /*
 122          * Determine source device and port.
 123          */
 124         source_device = edsa_header[0] & 0x1f;
 125         source_port = (edsa_header[1] >> 3) & 0x1f;
 126
 127         /*
 128          * Check that the source device exists and that the source
 129          * port is a registered DSA port.
 130          */
 131         if (source_device >= dst->pd->nr_chips)
 132                 goto out_drop;
 133         ds = dst->ds[source_device];
 134         if (source_port >= DSA_MAX_PORTS || ds->ports[source_port] == NULL)
 135                 goto out_drop;
 136
 137         /*
 138          * If the 'tagged' bit is set, convert the DSA tag to a 802.1q
 139          * tag and delete the ethertype part.  If the 'tagged' bit is
 140          * clear, delete the ethertype and the DSA tag parts.
 141          */
 142         if (edsa_header[0] & 0x20) {
 143                 u8 new_header[4];
 144
 145                 /*
 146                  * Insert 802.1q ethertype and copy the VLAN-related
 147                  * fields, but clear the bit that will hold CFI (since
 148                  * DSA uses that bit location for another purpose).
 149                  */
 150                 new_header[0] = (ETH_P_8021Q >> 8) & 0xff;
 151                 new_header[1] = ETH_P_8021Q & 0xff;
 152                 new_header[2] = edsa_header[2] & ~0x10;
 153                 new_header[3] = edsa_header[3];
 154
 155                 /*
 156                  * Move CFI bit from its place in the DSA header to
 157                  * its 802.1q-designated place.
 158                  */
 159                 if (edsa_header[1] & 0x01)
 160                         new_header[2] |= 0x10;
 161
 162                 skb_pull_rcsum(skb, DSA_HLEN);
 163
 164                 /*
 165                  * Update packet checksum if skb is CHECKSUM_COMPLETE.
 166                  */
 167                 if (skb->ip_summed == CHECKSUM_COMPLETE) {
 168                         __wsum c = skb->csum;
 169                         c = csum_add(c, csum_partial(new_header + 2, 2, 0));
 170                         c = csum_sub(c, csum_partial(edsa_header + 2, 2, 0));
 171                         skb->csum = c;
 172                 }
 173
 174                 memcpy(edsa_header, new_header, DSA_HLEN);
 175
 176                 memmove(skb->data - ETH_HLEN,
 177                         skb->data - ETH_HLEN - DSA_HLEN,
 178                         2 * ETH_ALEN);
 179         } else {
 180                 /*
 181                  * Remove DSA tag and update checksum.
 182                  */
 183                 skb_pull_rcsum(skb, EDSA_HLEN);
 184                 memmove(skb->data - ETH_HLEN,
 185                         skb->data - ETH_HLEN - EDSA_HLEN,
 186                         2 * ETH_ALEN);
 187         }
 188
 189         skb->dev = ds->ports[source_port];
 190         skb_push(skb, ETH_HLEN);
 191         skb->pkt_type = PACKET_HOST;
 192         skb->protocol = eth_type_trans(skb, skb->dev);
 193
 194         skb->dev->stats.rx_packets++;
 195         skb->dev->stats.rx_bytes += skb->len;
 196
 197         netif_receive_skb(skb);
 198
 199         return 0;
 200
 201 out_drop:
 202         kfree_skb(skb);
 203 out:
 204         return 0;
 205 }
 206
 207 static struct packet_type edsa_packet_type __read_mostly = {
 208         .type   = cpu_to_be16(ETH_P_EDSA),
 209         .func   = edsa_rcv,
 210 };
 211
 212 static int __init edsa_init_module(void)
 213 {
 214         dev_add_pack(&edsa_packet_type);
 215         return 0;
 216 }
 217 module_init(edsa_init_module);
 218
 219 static void __exit edsa_cleanup_module(void)
 220 {
 221         dev_remove_pack(&edsa_packet_type);
 222 }
 223 module_exit(edsa_cleanup_module);