net/dsa/tag_dsa.c

   1 /*
   2  * net/dsa/tag_dsa.c - (Non-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
  18 netdev_tx_t 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 | p->parent->index;
  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 | p->parent->index;
  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->dst->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_tree *dst = dev->dsa_ptr;
  82         struct dsa_switch *ds;
  83         u8 *dsa_header;
  84         int source_device;
  85         int source_port;
  86
  87         if (unlikely(dst == NULL))
  88                 goto out_drop;
  89
  90         skb = skb_unshare(skb, GFP_ATOMIC);
  91         if (skb == NULL)
  92                 goto out;
  93
  94         if (unlikely(!pskb_may_pull(skb, DSA_HLEN)))
  95                 goto out_drop;
  96
  97         /*
  98          * The ethertype field is part of the DSA header.
  99          */
 100         dsa_header = skb->data - 2;
 101
 102         /*
 103          * Check that frame type is either TO_CPU or FORWARD.
 104          */
 105         if ((dsa_header[0] & 0xc0) != 0x00 && (dsa_header[0] & 0xc0) != 0xc0)
 106                 goto out_drop;
 107
 108         /*
 109          * Determine source device and port.
 110          */
 111         source_device = dsa_header[0] & 0x1f;
 112         source_port = (dsa_header[1] >> 3) & 0x1f;
 113
 114         /*
 115          * Check that the source device exists and that the source
 116          * port is a registered DSA port.
 117          */
 118         if (source_device >= dst->pd->nr_chips)
 119                 goto out_drop;
 120         ds = dst->ds[source_device];
 121         if (source_port >= DSA_MAX_PORTS || ds->ports[source_port] == NULL)
 122                 goto out_drop;
 123
 124         /*
 125          * Convert the DSA header to an 802.1q header if the 'tagged'
 126          * bit in the DSA header is set.  If the 'tagged' bit is clear,
 127          * delete the DSA header entirely.
 128          */
 129         if (dsa_header[0] & 0x20) {
 130                 u8 new_header[4];
 131
 132                 /*
 133                  * Insert 802.1q ethertype and copy the VLAN-related
 134                  * fields, but clear the bit that will hold CFI (since
 135                  * DSA uses that bit location for another purpose).
 136                  */
 137                 new_header[0] = (ETH_P_8021Q >> 8) & 0xff;
 138                 new_header[1] = ETH_P_8021Q & 0xff;
 139                 new_header[2] = dsa_header[2] & ~0x10;
 140                 new_header[3] = dsa_header[3];
 141
 142                 /*
 143                  * Move CFI bit from its place in the DSA header to
 144                  * its 802.1q-designated place.
 145                  */
 146                 if (dsa_header[1] & 0x01)
 147                         new_header[2] |= 0x10;
 148
 149                 /*
 150                  * Update packet checksum if skb is CHECKSUM_COMPLETE.
 151                  */
 152                 if (skb->ip_summed == CHECKSUM_COMPLETE) {
 153                         __wsum c = skb->csum;
 154                         c = csum_add(c, csum_partial(new_header + 2, 2, 0));
 155                         c = csum_sub(c, csum_partial(dsa_header + 2, 2, 0));
 156                         skb->csum = c;
 157                 }
 158
 159                 memcpy(dsa_header, new_header, DSA_HLEN);
 160         } else {
 161                 /*
 162                  * Remove DSA tag and update checksum.
 163                  */
 164                 skb_pull_rcsum(skb, DSA_HLEN);
 165                 memmove(skb->data - ETH_HLEN,
 166                         skb->data - ETH_HLEN - DSA_HLEN,
 167                         2 * ETH_ALEN);
 168         }
 169
 170         skb->dev = ds->ports[source_port];
 171         skb_push(skb, ETH_HLEN);
 172         skb->pkt_type = PACKET_HOST;
 173         skb->protocol = eth_type_trans(skb, skb->dev);
 174
 175         skb->dev->stats.rx_packets++;
 176         skb->dev->stats.rx_bytes += skb->len;
 177
 178         netif_receive_skb(skb);
 179
 180         return 0;
 181
 182 out_drop:
 183         kfree_skb(skb);
 184 out:
 185         return 0;
 186 }
 187
 188 static struct packet_type dsa_packet_type __read_mostly = {
 189         .type   = cpu_to_be16(ETH_P_DSA),
 190         .func   = dsa_rcv,
 191 };
 192
 193 static int __init dsa_init_module(void)
 194 {
 195         dev_add_pack(&dsa_packet_type);
 196         return 0;
 197 }
 198 module_init(dsa_init_module);
 199
 200 static void __exit dsa_cleanup_module(void)
 201 {
 202         dev_remove_pack(&dsa_packet_type);
 203 }
 204 module_exit(dsa_cleanup_module);