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