drivers/net/arcnet/rfc1051.c

   1 /*
   2  * Linux ARCnet driver - RFC1051 ("simple" standard) packet encapsulation
   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 #include <linux/module.h>
  27 #include <linux/init.h>
  28 #include <linux/if_arp.h>
  29 #include <net/arp.h>
  30 #include <linux/netdevice.h>
  31 #include <linux/skbuff.h>
  32 #include <linux/arcdevice.h>
  33
  34 #define VERSION "arcnet: RFC1051 \"simple standard\" (`s') encapsulation support loaded.\n"
  35
  36
  37 static __be16 type_trans(struct sk_buff *skb, struct net_device *dev);
  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
  46 static struct ArcProto rfc1051_proto =
  47 {
  48         .suffix         = 's',
  49         .mtu            = XMTU - RFC1051_HDR_SIZE,
  50         .is_ip          = 1,
  51         .rx             = rx,
  52         .build_header   = build_header,
  53         .prepare_tx     = prepare_tx,
  54         .continue_tx    = NULL,
  55         .ack_tx         = NULL
  56 };
  57
  58
  59 static int __init arcnet_rfc1051_init(void)
  60 {
  61         printk(VERSION);
  62
  63         arc_proto_map[ARC_P_IP_RFC1051]
  64             = arc_proto_map[ARC_P_ARP_RFC1051]
  65             = &rfc1051_proto;
  66
  67         /* if someone else already owns the broadcast, we won't take it */
  68         if (arc_bcast_proto == arc_proto_default)
  69                 arc_bcast_proto = &rfc1051_proto;
  70
  71         return 0;
  72 }
  73
  74 static void __exit arcnet_rfc1051_exit(void)
  75 {
  76         arcnet_unregister_proto(&rfc1051_proto);
  77 }
  78
  79 module_init(arcnet_rfc1051_init);
  80 module_exit(arcnet_rfc1051_exit);
  81
  82 MODULE_LICENSE("GPL");
  83
  84 /*
  85  * Determine a packet's protocol ID.
  86  *
  87  * With ARCnet we have to convert everything to Ethernet-style stuff.
  88  */
  89 static __be16 type_trans(struct sk_buff *skb, struct net_device *dev)
  90 {
  91         struct archdr *pkt = (struct archdr *) skb->data;
  92         struct arc_rfc1051 *soft = &pkt->soft.rfc1051;
  93         int hdr_size = ARC_HDR_SIZE + RFC1051_HDR_SIZE;
  94
  95         /* Pull off the arcnet header. */
  96         skb_reset_mac_header(skb);
  97         skb_pull(skb, hdr_size);
  98
  99         if (pkt->hard.dest == 0)
 100                 skb->pkt_type = PACKET_BROADCAST;
 101         else if (dev->flags & IFF_PROMISC) {
 102                 /* if we're not sending to ourselves :) */
 103                 if (pkt->hard.dest != dev->dev_addr[0])
 104                         skb->pkt_type = PACKET_OTHERHOST;
 105         }
 106         /* now return the protocol number */
 107         switch (soft->proto) {
 108         case ARC_P_IP_RFC1051:
 109                 return htons(ETH_P_IP);
 110         case ARC_P_ARP_RFC1051:
 111                 return htons(ETH_P_ARP);
 112
 113         default:
 114                 dev->stats.rx_errors++;
 115                 dev->stats.rx_crc_errors++;
 116                 return 0;
 117         }
 118
 119         return htons(ETH_P_IP);
 120 }
 121
 122
 123 /* packet receiver */
 124 static void rx(struct net_device *dev, int bufnum,
 125                struct archdr *pkthdr, int length)
 126 {
 127         struct arcnet_local *lp = netdev_priv(dev);
 128         struct sk_buff *skb;
 129         struct archdr *pkt = pkthdr;
 130         int ofs;
 131
 132         BUGMSG(D_DURING, "it's a raw packet (length=%d)\n", length);
 133
 134         if (length >= MinTU)
 135                 ofs = 512 - length;
 136         else
 137                 ofs = 256 - length;
 138
 139         skb = alloc_skb(length + ARC_HDR_SIZE, GFP_ATOMIC);
 140         if (skb == NULL) {
 141                 BUGMSG(D_NORMAL, "Memory squeeze, dropping packet.\n");
 142                 dev->stats.rx_dropped++;
 143                 return;
 144         }
 145         skb_put(skb, length + ARC_HDR_SIZE);
 146         skb->dev = dev;
 147
 148         pkt = (struct archdr *) skb->data;
 149
 150         /* up to sizeof(pkt->soft) has already been copied from the card */
 151         memcpy(pkt, pkthdr, sizeof(struct archdr));
 152         if (length > sizeof(pkt->soft))
 153                 lp->hw.copy_from_card(dev, bufnum, ofs + sizeof(pkt->soft),
 154                                       pkt->soft.raw + sizeof(pkt->soft),
 155                                       length - sizeof(pkt->soft));
 156
 157         BUGLVL(D_SKB) arcnet_dump_skb(dev, skb, "rx");
 158
 159         skb->protocol = type_trans(skb, dev);
 160         netif_rx(skb);
 161 }
 162
 163
 164 /*
 165  * Create the ARCnet hard/soft headers for RFC1051.
 166  */
 167 static int build_header(struct sk_buff *skb, struct net_device *dev,
 168                         unsigned short type, uint8_t daddr)
 169 {
 170         int hdr_size = ARC_HDR_SIZE + RFC1051_HDR_SIZE;
 171         struct archdr *pkt = (struct archdr *) skb_push(skb, hdr_size);
 172         struct arc_rfc1051 *soft = &pkt->soft.rfc1051;
 173
 174         /* set the protocol ID according to RFC1051 */
 175         switch (type) {
 176         case ETH_P_IP:
 177                 soft->proto = ARC_P_IP_RFC1051;
 178                 break;
 179         case ETH_P_ARP:
 180                 soft->proto = ARC_P_ARP_RFC1051;
 181                 break;
 182         default:
 183                 BUGMSG(D_NORMAL, "RFC1051: I don't understand protocol %d (%Xh)\n",
 184                        type, type);
 185                 dev->stats.tx_errors++;
 186                 dev->stats.tx_aborted_errors++;
 187                 return 0;
 188         }
 189
 190
 191         /*
 192          * Set the source hardware address.
 193          *
 194          * This is pretty pointless for most purposes, but it can help in
 195          * debugging.  ARCnet does not allow us to change the source address in
 196          * the actual packet sent)
 197          */
 198         pkt->hard.source = *dev->dev_addr;
 199
 200         /* see linux/net/ethernet/eth.c to see where I got the following */
 201
 202         if (dev->flags & (IFF_LOOPBACK | IFF_NOARP)) {
 203                 /*
 204                  * FIXME: fill in the last byte of the dest ipaddr here to better
 205                  * comply with RFC1051 in "noarp" mode.
 206                  */
 207                 pkt->hard.dest = 0;
 208                 return hdr_size;
 209         }
 210         /* otherwise, just fill it in and go! */
 211         pkt->hard.dest = daddr;
 212
 213         return hdr_size;        /* success */
 214 }
 215
 216
 217 static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
 218                       int bufnum)
 219 {
 220         struct arcnet_local *lp = netdev_priv(dev);
 221         struct arc_hardware *hard = &pkt->hard;
 222         int ofs;
 223
 224         BUGMSG(D_DURING, "prepare_tx: txbufs=%d/%d/%d\n",
 225                lp->next_tx, lp->cur_tx, bufnum);
 226
 227         length -= ARC_HDR_SIZE; /* hard header is not included in packet length */
 228
 229         if (length > XMTU) {
 230                 /* should never happen! other people already check for this. */
 231                 BUGMSG(D_NORMAL, "Bug!  prepare_tx with size %d (> %d)\n",
 232                        length, XMTU);
 233                 length = XMTU;
 234         }
 235         if (length > MinTU) {
 236                 hard->offset[0] = 0;
 237                 hard->offset[1] = ofs = 512 - length;
 238         } else if (length > MTU) {
 239                 hard->offset[0] = 0;
 240                 hard->offset[1] = ofs = 512 - length - 3;
 241         } else
 242                 hard->offset[0] = ofs = 256 - length;
 243
 244         lp->hw.copy_to_card(dev, bufnum, 0, hard, ARC_HDR_SIZE);
 245         lp->hw.copy_to_card(dev, bufnum, ofs, &pkt->soft, length);
 246
 247         lp->lastload_dest = hard->dest;
 248
 249         return 1;               /* done */
 250 }