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