linux/net/dsa/tag_edsa.c
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   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
  20netdev_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
  87out_free:
  88        kfree_skb(skb);
  89        return NETDEV_TX_OK;
  90}
  91
  92static 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
 202out_drop:
 203        kfree_skb(skb);
 204out:
 205        return 0;
 206}
 207
 208struct packet_type edsa_packet_type __read_mostly = {
 209        .type   = cpu_to_be16(ETH_P_EDSA),
 210        .func   = edsa_rcv,
 211};
 212
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