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/slab.h>
  14 #include "dsa_priv.h"
  15
  16 #define DSA_HLEN        4
  17
  18 static 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->dev = p->parent->dst->master_netdev;
  67         dev_queue_xmit(skb);
  68
  69         return NETDEV_TX_OK;
  70
  71 out_free:
  72         kfree_skb(skb);
  73         return NETDEV_TX_OK;
  74 }
  75
  76 static int dsa_rcv(struct sk_buff *skb, struct net_device *dev,
  77                    struct packet_type *pt, struct net_device *orig_dev)
  78 {
  79         struct dsa_switch_tree *dst = dev->dsa_ptr;
  80         struct dsa_switch *ds;
  81         u8 *dsa_header;
  82         int source_device;
  83         int source_port;
  84
  85         if (unlikely(dst == 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.
 102          */
 103         if ((dsa_header[0] & 0xc0) != 0x00 && (dsa_header[0] & 0xc0) != 0xc0)
 104                 goto out_drop;
 105
 106         /*
 107          * Determine source device and port.
 108          */
 109         source_device = dsa_header[0] & 0x1f;
 110         source_port = (dsa_header[1] >> 3) & 0x1f;
 111
 112         /*
 113          * Check that the source device exists and that the source
 114          * port is a registered DSA port.
 115          */
 116         if (source_device >= dst->pd->nr_chips)
 117                 goto out_drop;
 118         ds = dst->ds[source_device];
 119         if (source_port >= DSA_MAX_PORTS || ds->ports[source_port] == NULL)
 120                 goto out_drop;
 121
 122         /*
 123          * Convert the DSA header to an 802.1q header if the 'tagged'
 124          * bit in the DSA header is set.  If the 'tagged' bit is clear,
 125          * delete the DSA header entirely.
 126          */
 127         if (dsa_header[0] & 0x20) {
 128                 u8 new_header[4];
 129
 130                 /*
 131                  * Insert 802.1q ethertype and copy the VLAN-related
 132                  * fields, but clear the bit that will hold CFI (since
 133                  * DSA uses that bit location for another purpose).
 134                  */
 135                 new_header[0] = (ETH_P_8021Q >> 8) & 0xff;
 136                 new_header[1] = ETH_P_8021Q & 0xff;
 137                 new_header[2] = dsa_header[2] & ~0x10;
 138                 new_header[3] = dsa_header[3];
 139
 140                 /*
 141                  * Move CFI bit from its place in the DSA header to
 142                  * its 802.1q-designated place.
 143                  */
 144                 if (dsa_header[1] & 0x01)
 145                         new_header[2] |= 0x10;
 146
 147                 /*
 148                  * Update packet checksum if skb is CHECKSUM_COMPLETE.
 149                  */
 150                 if (skb->ip_summed == CHECKSUM_COMPLETE) {
 151                         __wsum c = skb->csum;
 152                         c = csum_add(c, csum_partial(new_header + 2, 2, 0));
 153                         c = csum_sub(c, csum_partial(dsa_header + 2, 2, 0));
 154                         skb->csum = c;
 155                 }
 156
 157                 memcpy(dsa_header, new_header, DSA_HLEN);
 158         } else {
 159                 /*
 160                  * Remove DSA tag and update checksum.
 161                  */
 162                 skb_pull_rcsum(skb, DSA_HLEN);
 163                 memmove(skb->data - ETH_HLEN,
 164                         skb->data - ETH_HLEN - DSA_HLEN,
 165                         2 * ETH_ALEN);
 166         }
 167
 168         skb->dev = ds->ports[source_port];
 169         skb_push(skb, ETH_HLEN);
 170         skb->pkt_type = PACKET_HOST;
 171         skb->protocol = eth_type_trans(skb, skb->dev);
 172
 173         skb->dev->stats.rx_packets++;
 174         skb->dev->stats.rx_bytes += skb->len;
 175
 176         netif_receive_skb(skb);
 177
 178         return 0;
 179
 180 out_drop:
 181         kfree_skb(skb);
 182 out:
 183         return 0;
 184 }
 185
 186 const struct dsa_device_ops dsa_netdev_ops = {
 187         .xmit   = dsa_xmit,
 188         .rcv    = dsa_rcv,
 189 };