linux/drivers/net/arcnet/arc-rawmode.c
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   1/*
   2 * Linux ARCnet driver - "raw mode" packet encapsulation (no soft headers)
   3 *
   4 * Written 1994-1999 by Avery Pennarun.
   5 * Derived from skeleton.c by Donald Becker.
   6 *
   7 * Special thanks to Contemporary Controls, Inc. (www.ccontrols.com)
   8 *  for sponsoring the further development of this driver.
   9 *
  10 * **********************
  11 *
  12 * The original copyright of skeleton.c was as follows:
  13 *
  14 * skeleton.c Written 1993 by Donald Becker.
  15 * Copyright 1993 United States Government as represented by the
  16 * Director, National Security Agency.  This software may only be used
  17 * and distributed according to the terms of the GNU General Public License as
  18 * modified by SRC, incorporated herein by reference.
  19 *
  20 * **********************
  21 *
  22 * For more details, see drivers/net/arcnet.c
  23 *
  24 * **********************
  25 */
  26
  27#define pr_fmt(fmt) "arcnet:" KBUILD_MODNAME ": " fmt
  28
  29#include <linux/module.h>
  30#include <linux/gfp.h>
  31#include <linux/init.h>
  32#include <linux/if_arp.h>
  33#include <net/arp.h>
  34#include <linux/netdevice.h>
  35#include <linux/skbuff.h>
  36#include "arcdevice.h"
  37
  38/* packet receiver */
  39static void rx(struct net_device *dev, int bufnum,
  40               struct archdr *pkthdr, int length)
  41{
  42        struct arcnet_local *lp = netdev_priv(dev);
  43        struct sk_buff *skb;
  44        struct archdr *pkt = pkthdr;
  45        int ofs;
  46
  47        arc_printk(D_DURING, dev, "it's a raw packet (length=%d)\n", length);
  48
  49        if (length > MTU)
  50                ofs = 512 - length;
  51        else
  52                ofs = 256 - length;
  53
  54        skb = alloc_skb(length + ARC_HDR_SIZE, GFP_ATOMIC);
  55        if (!skb) {
  56                dev->stats.rx_dropped++;
  57                return;
  58        }
  59        skb_put(skb, length + ARC_HDR_SIZE);
  60        skb->dev = dev;
  61
  62        pkt = (struct archdr *)skb->data;
  63
  64        skb_reset_mac_header(skb);
  65        skb_pull(skb, ARC_HDR_SIZE);
  66
  67        /* up to sizeof(pkt->soft) has already been copied from the card */
  68        memcpy(pkt, pkthdr, sizeof(struct archdr));
  69        if (length > sizeof(pkt->soft))
  70                lp->hw.copy_from_card(dev, bufnum, ofs + sizeof(pkt->soft),
  71                                      pkt->soft.raw + sizeof(pkt->soft),
  72                                      length - sizeof(pkt->soft));
  73
  74        if (BUGLVL(D_SKB))
  75                arcnet_dump_skb(dev, skb, "rx");
  76
  77        skb->protocol = cpu_to_be16(ETH_P_ARCNET);
  78        netif_rx(skb);
  79}
  80
  81/* Create the ARCnet hard/soft headers for raw mode.
  82 * There aren't any soft headers in raw mode - not even the protocol id.
  83 */
  84static int build_header(struct sk_buff *skb, struct net_device *dev,
  85                        unsigned short type, uint8_t daddr)
  86{
  87        int hdr_size = ARC_HDR_SIZE;
  88        struct archdr *pkt = (struct archdr *)skb_push(skb, hdr_size);
  89
  90        /* Set the source hardware address.
  91         *
  92         * This is pretty pointless for most purposes, but it can help in
  93         * debugging.  ARCnet does not allow us to change the source address
  94         * in the actual packet sent.
  95         */
  96        pkt->hard.source = *dev->dev_addr;
  97
  98        /* see linux/net/ethernet/eth.c to see where I got the following */
  99
 100        if (dev->flags & (IFF_LOOPBACK | IFF_NOARP)) {
 101                /* FIXME: fill in the last byte of the dest ipaddr here
 102                 * to better comply with RFC1051 in "noarp" mode.
 103                 */
 104                pkt->hard.dest = 0;
 105                return hdr_size;
 106        }
 107        /* otherwise, just fill it in and go! */
 108        pkt->hard.dest = daddr;
 109
 110        return hdr_size;        /* success */
 111}
 112
 113static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
 114                      int bufnum)
 115{
 116        struct arcnet_local *lp = netdev_priv(dev);
 117        struct arc_hardware *hard = &pkt->hard;
 118        int ofs;
 119
 120        arc_printk(D_DURING, dev, "prepare_tx: txbufs=%d/%d/%d\n",
 121                   lp->next_tx, lp->cur_tx, bufnum);
 122
 123        /* hard header is not included in packet length */
 124        length -= ARC_HDR_SIZE;
 125
 126        if (length > XMTU) {
 127                /* should never happen! other people already check for this. */
 128                arc_printk(D_NORMAL, dev, "Bug!  prepare_tx with size %d (> %d)\n",
 129                           length, XMTU);
 130                length = XMTU;
 131        }
 132        if (length >= MinTU) {
 133                hard->offset[0] = 0;
 134                hard->offset[1] = ofs = 512 - length;
 135        } else if (length > MTU) {
 136                hard->offset[0] = 0;
 137                hard->offset[1] = ofs = 512 - length - 3;
 138        } else {
 139                hard->offset[0] = ofs = 256 - length;
 140        }
 141
 142        arc_printk(D_DURING, dev, "prepare_tx: length=%d ofs=%d\n",
 143                   length, ofs);
 144
 145        lp->hw.copy_to_card(dev, bufnum, 0, hard, ARC_HDR_SIZE);
 146        lp->hw.copy_to_card(dev, bufnum, ofs, &pkt->soft, length);
 147
 148        lp->lastload_dest = hard->dest;
 149
 150        return 1;               /* done */
 151}
 152
 153static struct ArcProto rawmode_proto = {
 154        .suffix         = 'r',
 155        .mtu            = XMTU,
 156        .rx             = rx,
 157        .build_header   = build_header,
 158        .prepare_tx     = prepare_tx,
 159        .continue_tx    = NULL,
 160        .ack_tx         = NULL
 161};
 162
 163static int __init arcnet_raw_init(void)
 164{
 165        int count;
 166
 167        pr_info("raw mode (`r') encapsulation support loaded\n");
 168
 169        for (count = 0; count < 256; count++)
 170                if (arc_proto_map[count] == arc_proto_default)
 171                        arc_proto_map[count] = &rawmode_proto;
 172
 173        /* for raw mode, we only set the bcast proto if there's no better one */
 174        if (arc_bcast_proto == arc_proto_default)
 175                arc_bcast_proto = &rawmode_proto;
 176
 177        arc_proto_default = &rawmode_proto;
 178        return 0;
 179}
 180
 181static void __exit arcnet_raw_exit(void)
 182{
 183        arcnet_unregister_proto(&rawmode_proto);
 184}
 185
 186module_init(arcnet_raw_init);
 187module_exit(arcnet_raw_exit);
 188
 189MODULE_LICENSE("GPL");
 190