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 <linux/slab.h>
  15 #include "dsa_priv.h"
  16
  17 #define DSA_HLEN        4
  18 #define EDSA_HLEN       8
  19
  20 netdev_tx_t edsa_xmit(struct sk_buff *skb, struct net_device *dev)
  21 {
  22         struct dsa_slave_priv *p = netdev_priv(dev);
  23         u8 *edsa_header;
  24
  25         dev->stats.tx_packets++;
  26         dev->stats.tx_bytes += skb->len;
  27
  28         /*
  29          * Convert the outermost 802.1q tag to a DSA tag and prepend
  30          * a DSA ethertype field is the packet is tagged, or insert
  31          * a DSA ethertype plus DSA tag between the addresses and the
  32          * current ethertype field if the packet is untagged.
  33          */
  34         if (skb->protocol == htons(ETH_P_8021Q)) {
  35                 if (skb_cow_head(skb, DSA_HLEN) < 0)
  36                         goto out_free;
  37                 skb_push(skb, DSA_HLEN);
  38
  39                 memmove(skb->data, skb->data + DSA_HLEN, 2 * ETH_ALEN);
  40
  41                 /*
  42                  * Construct tagged FROM_CPU DSA tag from 802.1q tag.
  43                  */
  44                 edsa_header = skb->data + 2 * ETH_ALEN;
  45                 edsa_header[0] = (ETH_P_EDSA >> 8) & 0xff;
  46                 edsa_header[1] = ETH_P_EDSA & 0xff;
  47                 edsa_header[2] = 0x00;
  48                 edsa_header[3] = 0x00;
  49                 edsa_header[4] = 0x60 | p->parent->index;
  50                 edsa_header[5] = p->port << 3;
  51
  52                 /*
  53                  * Move CFI field from byte 6 to byte 5.
  54                  */
  55                 if (edsa_header[6] & 0x10) {
  56                         edsa_header[5] |= 0x01;
  57                         edsa_header[6] &= ~0x10;
  58                 }
  59         } else {
  60                 if (skb_cow_head(skb, EDSA_HLEN) < 0)
  61                         goto out_free;
  62                 skb_push(skb, EDSA_HLEN);
  63
  64                 memmove(skb->data, skb->data + EDSA_HLEN, 2 * ETH_ALEN);
  65
  66                 /*
  67                  * Construct untagged FROM_CPU DSA tag.
  68                  */
  69                 edsa_header = skb->data + 2 * ETH_ALEN;
  70                 edsa_header[0] = (ETH_P_EDSA >> 8) & 0xff;
  71                 edsa_header[1] = ETH_P_EDSA & 0xff;
  72                 edsa_header[2] = 0x00;
  73                 edsa_header[3] = 0x00;
  74                 edsa_header[4] = 0x40 | p->parent->index;
  75                 edsa_header[5] = p->port << 3;
  76                 edsa_header[6] = 0x00;
  77                 edsa_header[7] = 0x00;
  78         }
  79
  80         skb->protocol = htons(ETH_P_EDSA);
  81
  82         skb->dev = p->parent->dst->master_netdev;
  83         dev_queue_xmit(skb);
  84
  85         return NETDEV_TX_OK;
  86
  87 out_free:
  88         kfree_skb(skb);
  89         return NETDEV_TX_OK;
  90 }
  91
  92 static int edsa_rcv(struct sk_buff *skb, struct net_device *dev,
  93                     struct packet_type *pt, struct net_device *orig_dev)
  94 {
  95         struct dsa_switch_tree *dst = dev->dsa_ptr;
  96         struct dsa_switch *ds;
  97         u8 *edsa_header;
  98         int source_device;
  99         int source_port;
 100
 101         if (unlikely(dst == NULL))
 102                 goto out_drop;
 103
 104         skb = skb_unshare(skb, GFP_ATOMIC);
 105         if (skb == NULL)
 106                 goto out;
 107
 108         if (unlikely(!pskb_may_pull(skb, EDSA_HLEN)))
 109                 goto out_drop;
 110
 111         /*
 112          * Skip the two null bytes after the ethertype.
 113          */
 114         edsa_header = skb->data + 2;
 115
 116         /*
 117          * Check that frame type is either TO_CPU or FORWARD.
 118          */
 119         if ((edsa_header[0] & 0xc0) != 0x00 && (edsa_header[0] & 0xc0) != 0xc0)
 120                 goto out_drop;
 121
 122         /*
 123          * Determine source device and port.
 124          */
 125         source_device = edsa_header[0] & 0x1f;
 126         source_port = (edsa_header[1] >> 3) & 0x1f;
 127
 128         /*
 129          * Check that the source device exists and that the source
 130          * port is a registered DSA port.
 131          */
 132         if (source_device >= dst->pd->nr_chips)
 133                 goto out_drop;
 134         ds = dst->ds[source_device];
 135         if (source_port >= DSA_MAX_PORTS || ds->ports[source_port] == NULL)
 136                 goto out_drop;
 137
 138         /*
 139          * If the 'tagged' bit is set, convert the DSA tag to a 802.1q
 140          * tag and delete the ethertype part.  If the 'tagged' bit is
 141          * clear, delete the ethertype and the DSA tag parts.
 142          */
 143         if (edsa_header[0] & 0x20) {
 144                 u8 new_header[4];
 145
 146                 /*
 147                  * Insert 802.1q ethertype and copy the VLAN-related
 148                  * fields, but clear the bit that will hold CFI (since
 149                  * DSA uses that bit location for another purpose).
 150                  */
 151                 new_header[0] = (ETH_P_8021Q >> 8) & 0xff;
 152                 new_header[1] = ETH_P_8021Q & 0xff;
 153                 new_header[2] = edsa_header[2] & ~0x10;
 154                 new_header[3] = edsa_header[3];
 155
 156                 /*
 157                  * Move CFI bit from its place in the DSA header to
 158                  * its 802.1q-designated place.
 159                  */
 160                 if (edsa_header[1] & 0x01)
 161                         new_header[2] |= 0x10;
 162
 163                 skb_pull_rcsum(skb, DSA_HLEN);
 164
 165                 /*
 166                  * Update packet checksum if skb is CHECKSUM_COMPLETE.
 167                  */
 168                 if (skb->ip_summed == CHECKSUM_COMPLETE) {
 169                         __wsum c = skb->csum;
 170                         c = csum_add(c, csum_partial(new_header + 2, 2, 0));
 171                         c = csum_sub(c, csum_partial(edsa_header + 2, 2, 0));
 172                         skb->csum = c;
 173                 }
 174
 175                 memcpy(edsa_header, new_header, DSA_HLEN);
 176
 177                 memmove(skb->data - ETH_HLEN,
 178                         skb->data - ETH_HLEN - DSA_HLEN,
 179                         2 * ETH_ALEN);
 180         } else {
 181                 /*
 182                  * Remove DSA tag and update checksum.
 183                  */
 184                 skb_pull_rcsum(skb, EDSA_HLEN);
 185                 memmove(skb->data - ETH_HLEN,
 186                         skb->data - ETH_HLEN - EDSA_HLEN,
 187                         2 * ETH_ALEN);
 188         }
 189
 190         skb->dev = ds->ports[source_port];
 191         skb_push(skb, ETH_HLEN);
 192         skb->pkt_type = PACKET_HOST;
 193         skb->protocol = eth_type_trans(skb, skb->dev);
 194
 195         skb->dev->stats.rx_packets++;
 196         skb->dev->stats.rx_bytes += skb->len;
 197
 198         netif_receive_skb(skb);
 199
 200         return 0;
 201
 202 out_drop:
 203         kfree_skb(skb);
 204 out:
 205         return 0;
 206 }
 207
 208 static struct packet_type edsa_packet_type __read_mostly = {
 209         .type   = cpu_to_be16(ETH_P_EDSA),
 210         .func   = edsa_rcv,
 211 };
 212
 213 static int __init edsa_init_module(void)
 214 {
 215         dev_add_pack(&edsa_packet_type);
 216         return 0;
 217 }
 218 module_init(edsa_init_module);
 219
 220 static void __exit edsa_cleanup_module(void)
 221 {
 222         dev_remove_pack(&edsa_packet_type);
 223 }
 224 module_exit(edsa_cleanup_module);