drivers/net/arcnet/arc-rawmode.c

   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 #include <linux/module.h>
  28 #include <linux/gfp.h>
  29 #include <linux/init.h>
  30 #include <linux/if_arp.h>
  31 #include <net/arp.h>
  32 #include <linux/netdevice.h>
  33 #include <linux/skbuff.h>
  34 #include <linux/arcdevice.h>
  35
  36 #define VERSION "arcnet: raw mode (`r') encapsulation support loaded.\n"
  37
  38
  39 static void rx(struct net_device *dev, int bufnum,
  40                struct archdr *pkthdr, int length);
  41 static int build_header(struct sk_buff *skb, struct net_device *dev,
  42                         unsigned short type, uint8_t daddr);
  43 static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
  44                       int bufnum);
  45
  46 static struct ArcProto rawmode_proto =
  47 {
  48         .suffix         = 'r',
  49         .mtu            = XMTU,
  50         .rx             = rx,
  51         .build_header   = build_header,
  52         .prepare_tx     = prepare_tx,
  53         .continue_tx    = NULL,
  54         .ack_tx         = NULL
  55 };
  56
  57
  58 static int __init arcnet_raw_init(void)
  59 {
  60         int count;
  61
  62         printk(VERSION);
  63
  64         for (count = 0; count < 256; count++)
  65                 if (arc_proto_map[count] == arc_proto_default)
  66                         arc_proto_map[count] = &rawmode_proto;
  67
  68         /* for raw mode, we only set the bcast proto if there's no better one */
  69         if (arc_bcast_proto == arc_proto_default)
  70                 arc_bcast_proto = &rawmode_proto;
  71
  72         arc_proto_default = &rawmode_proto;
  73         return 0;
  74 }
  75
  76 static void __exit arcnet_raw_exit(void)
  77 {
  78         arcnet_unregister_proto(&rawmode_proto);
  79 }
  80
  81 module_init(arcnet_raw_init);
  82 module_exit(arcnet_raw_exit);
  83
  84 MODULE_LICENSE("GPL");
  85
  86
  87 /* packet receiver */
  88 static void rx(struct net_device *dev, int bufnum,
  89                struct archdr *pkthdr, int length)
  90 {
  91         struct arcnet_local *lp = netdev_priv(dev);
  92         struct sk_buff *skb;
  93         struct archdr *pkt = pkthdr;
  94         int ofs;
  95
  96         BUGMSG(D_DURING, "it's a raw packet (length=%d)\n", length);
  97
  98         if (length > MTU)
  99                 ofs = 512 - length;
 100         else
 101                 ofs = 256 - length;
 102
 103         skb = alloc_skb(length + ARC_HDR_SIZE, GFP_ATOMIC);
 104         if (skb == NULL) {
 105                 BUGMSG(D_NORMAL, "Memory squeeze, dropping packet.\n");
 106                 dev->stats.rx_dropped++;
 107                 return;
 108         }
 109         skb_put(skb, length + ARC_HDR_SIZE);
 110         skb->dev = dev;
 111
 112         pkt = (struct archdr *) skb->data;
 113
 114         skb_reset_mac_header(skb);
 115         skb_pull(skb, ARC_HDR_SIZE);
 116
 117         /* up to sizeof(pkt->soft) has already been copied from the card */
 118         memcpy(pkt, pkthdr, sizeof(struct archdr));
 119         if (length > sizeof(pkt->soft))
 120                 lp->hw.copy_from_card(dev, bufnum, ofs + sizeof(pkt->soft),
 121                                       pkt->soft.raw + sizeof(pkt->soft),
 122                                       length - sizeof(pkt->soft));
 123
 124         BUGLVL(D_SKB) arcnet_dump_skb(dev, skb, "rx");
 125
 126         skb->protocol = cpu_to_be16(ETH_P_ARCNET);
 127         netif_rx(skb);
 128 }
 129
 130
 131 /*
 132  * Create the ARCnet hard/soft headers for raw mode.
 133  * There aren't any soft headers in raw mode - not even the protocol id.
 134  */
 135 static int build_header(struct sk_buff *skb, struct net_device *dev,
 136                         unsigned short type, uint8_t daddr)
 137 {
 138         int hdr_size = ARC_HDR_SIZE;
 139         struct archdr *pkt = (struct archdr *) skb_push(skb, hdr_size);
 140
 141         /*
 142          * Set the source hardware address.
 143          *
 144          * This is pretty pointless for most purposes, but it can help in
 145          * debugging.  ARCnet does not allow us to change the source address in
 146          * the actual packet sent)
 147          */
 148         pkt->hard.source = *dev->dev_addr;
 149
 150         /* see linux/net/ethernet/eth.c to see where I got the following */
 151
 152         if (dev->flags & (IFF_LOOPBACK | IFF_NOARP)) {
 153                 /*
 154                  * FIXME: fill in the last byte of the dest ipaddr here to better
 155                  * comply with RFC1051 in "noarp" mode.
 156                  */
 157                 pkt->hard.dest = 0;
 158                 return hdr_size;
 159         }
 160         /* otherwise, just fill it in and go! */
 161         pkt->hard.dest = daddr;
 162
 163         return hdr_size;        /* success */
 164 }
 165
 166
 167 static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
 168                       int bufnum)
 169 {
 170         struct arcnet_local *lp = netdev_priv(dev);
 171         struct arc_hardware *hard = &pkt->hard;
 172         int ofs;
 173
 174         BUGMSG(D_DURING, "prepare_tx: txbufs=%d/%d/%d\n",
 175                lp->next_tx, lp->cur_tx, bufnum);
 176
 177         length -= ARC_HDR_SIZE; /* hard header is not included in packet length */
 178
 179         if (length > XMTU) {
 180                 /* should never happen! other people already check for this. */
 181                 BUGMSG(D_NORMAL, "Bug!  prepare_tx with size %d (> %d)\n",
 182                        length, XMTU);
 183                 length = XMTU;
 184         }
 185         if (length >= MinTU) {
 186                 hard->offset[0] = 0;
 187                 hard->offset[1] = ofs = 512 - length;
 188         } else if (length > MTU) {
 189                 hard->offset[0] = 0;
 190                 hard->offset[1] = ofs = 512 - length - 3;
 191         } else
 192                 hard->offset[0] = ofs = 256 - length;
 193
 194         BUGMSG(D_DURING, "prepare_tx: length=%d ofs=%d\n",
 195                length,ofs);
 196
 197         lp->hw.copy_to_card(dev, bufnum, 0, hard, ARC_HDR_SIZE);
 198         lp->hw.copy_to_card(dev, bufnum, ofs, &pkt->soft, length);
 199
 200         lp->lastload_dest = hard->dest;
 201
 202         return 1;               /* done */
 203 }