linux/net/dsa/tag_dsa.c
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   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
  19netdev_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
  74out_free:
  75        kfree_skb(skb);
  76        return NETDEV_TX_OK;
  77}
  78
  79static 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
 183out_drop:
 184        kfree_skb(skb);
 185out:
 186        return 0;
 187}
 188
 189struct packet_type dsa_packet_type __read_mostly = {
 190        .type   = cpu_to_be16(ETH_P_DSA),
 191        .func   = dsa_rcv,
 192};
 193
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