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/gfp.h>
  28 #include <linux/init.h>
  29 #include <linux/if_arp.h>
  30 #include <net/arp.h>
  31 #include <linux/netdevice.h>
  32 #include <linux/skbuff.h>
  33 #include <linux/arcdevice.h>
  34
  35 #define VERSION "arcnet: RFC1051 \"simple standard\" (`s') encapsulation support loaded.\n"
  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 static struct ArcProto rfc1051_proto = {
  46         .suffix         = 's',
  47         .mtu            = XMTU - RFC1051_HDR_SIZE,
  48         .is_ip          = 1,
  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_rfc1051_init(void)
  57 {
  58         printk(VERSION);
  59
  60         arc_proto_map[ARC_P_IP_RFC1051]
  61             = arc_proto_map[ARC_P_ARP_RFC1051]
  62             = &rfc1051_proto;
  63
  64         /* if someone else already owns the broadcast, we won't take it */
  65         if (arc_bcast_proto == arc_proto_default)
  66                 arc_bcast_proto = &rfc1051_proto;
  67
  68         return 0;
  69 }
  70
  71 static void __exit arcnet_rfc1051_exit(void)
  72 {
  73         arcnet_unregister_proto(&rfc1051_proto);
  74 }
  75
  76 module_init(arcnet_rfc1051_init);
  77 module_exit(arcnet_rfc1051_exit);
  78
  79 MODULE_LICENSE("GPL");
  80
  81 /* Determine a packet's protocol ID.
  82  *
  83  * With ARCnet we have to convert everything to Ethernet-style stuff.
  84  */
  85 static __be16 type_trans(struct sk_buff *skb, struct net_device *dev)
  86 {
  87         struct archdr *pkt = (struct archdr *)skb->data;
  88         struct arc_rfc1051 *soft = &pkt->soft.rfc1051;
  89         int hdr_size = ARC_HDR_SIZE + RFC1051_HDR_SIZE;
  90
  91         /* Pull off the arcnet header. */
  92         skb_reset_mac_header(skb);
  93         skb_pull(skb, hdr_size);
  94
  95         if (pkt->hard.dest == 0) {
  96                 skb->pkt_type = PACKET_BROADCAST;
  97         } else if (dev->flags & IFF_PROMISC) {
  98                 /* if we're not sending to ourselves :) */
  99                 if (pkt->hard.dest != dev->dev_addr[0])
 100                         skb->pkt_type = PACKET_OTHERHOST;
 101         }
 102         /* now return the protocol number */
 103         switch (soft->proto) {
 104         case ARC_P_IP_RFC1051:
 105                 return htons(ETH_P_IP);
 106         case ARC_P_ARP_RFC1051:
 107                 return htons(ETH_P_ARP);
 108
 109         default:
 110                 dev->stats.rx_errors++;
 111                 dev->stats.rx_crc_errors++;
 112                 return 0;
 113         }
 114
 115         return htons(ETH_P_IP);
 116 }
 117
 118 /* packet receiver */
 119 static void rx(struct net_device *dev, int bufnum,
 120                struct archdr *pkthdr, int length)
 121 {
 122         struct arcnet_local *lp = netdev_priv(dev);
 123         struct sk_buff *skb;
 124         struct archdr *pkt = pkthdr;
 125         int ofs;
 126
 127         BUGMSG(D_DURING, "it's a raw packet (length=%d)\n", length);
 128
 129         if (length >= MinTU)
 130                 ofs = 512 - length;
 131         else
 132                 ofs = 256 - length;
 133
 134         skb = alloc_skb(length + ARC_HDR_SIZE, GFP_ATOMIC);
 135         if (skb == NULL) {
 136                 BUGMSG(D_NORMAL, "Memory squeeze, dropping packet.\n");
 137                 dev->stats.rx_dropped++;
 138                 return;
 139         }
 140         skb_put(skb, length + ARC_HDR_SIZE);
 141         skb->dev = dev;
 142
 143         pkt = (struct archdr *)skb->data;
 144
 145         /* up to sizeof(pkt->soft) has already been copied from the card */
 146         memcpy(pkt, pkthdr, sizeof(struct archdr));
 147         if (length > sizeof(pkt->soft))
 148                 lp->hw.copy_from_card(dev, bufnum, ofs + sizeof(pkt->soft),
 149                                       pkt->soft.raw + sizeof(pkt->soft),
 150                                       length - sizeof(pkt->soft));
 151
 152         if (BUGLVL(D_SKB))
 153                 arcnet_dump_skb(dev, skb, "rx");
 154
 155         skb->protocol = type_trans(skb, dev);
 156         netif_rx(skb);
 157 }
 158
 159 /* Create the ARCnet hard/soft headers for RFC1051 */
 160 static int build_header(struct sk_buff *skb, struct net_device *dev,
 161                         unsigned short type, uint8_t daddr)
 162 {
 163         int hdr_size = ARC_HDR_SIZE + RFC1051_HDR_SIZE;
 164         struct archdr *pkt = (struct archdr *)skb_push(skb, hdr_size);
 165         struct arc_rfc1051 *soft = &pkt->soft.rfc1051;
 166
 167         /* set the protocol ID according to RFC1051 */
 168         switch (type) {
 169         case ETH_P_IP:
 170                 soft->proto = ARC_P_IP_RFC1051;
 171                 break;
 172         case ETH_P_ARP:
 173                 soft->proto = ARC_P_ARP_RFC1051;
 174                 break;
 175         default:
 176                 BUGMSG(D_NORMAL, "RFC1051: I don't understand protocol %d (%Xh)\n",
 177                        type, type);
 178                 dev->stats.tx_errors++;
 179                 dev->stats.tx_aborted_errors++;
 180                 return 0;
 181         }
 182
 183         /* Set the source hardware address.
 184          *
 185          * This is pretty pointless for most purposes, but it can help in
 186          * debugging.  ARCnet does not allow us to change the source address
 187          * in the actual packet sent.
 188          */
 189         pkt->hard.source = *dev->dev_addr;
 190
 191         /* see linux/net/ethernet/eth.c to see where I got the following */
 192
 193         if (dev->flags & (IFF_LOOPBACK | IFF_NOARP)) {
 194                 /* FIXME: fill in the last byte of the dest ipaddr here to
 195                  * better comply with RFC1051 in "noarp" mode.
 196                  */
 197                 pkt->hard.dest = 0;
 198                 return hdr_size;
 199         }
 200         /* otherwise, just fill it in and go! */
 201         pkt->hard.dest = daddr;
 202
 203         return hdr_size;        /* success */
 204 }
 205
 206 static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
 207                       int bufnum)
 208 {
 209         struct arcnet_local *lp = netdev_priv(dev);
 210         struct arc_hardware *hard = &pkt->hard;
 211         int ofs;
 212
 213         BUGMSG(D_DURING, "prepare_tx: txbufs=%d/%d/%d\n",
 214                lp->next_tx, lp->cur_tx, bufnum);
 215
 216         length -= ARC_HDR_SIZE; /* hard header is not included in packet length */
 217
 218         if (length > XMTU) {
 219                 /* should never happen! other people already check for this. */
 220                 BUGMSG(D_NORMAL, "Bug!  prepare_tx with size %d (> %d)\n",
 221                        length, XMTU);
 222                 length = XMTU;
 223         }
 224         if (length > MinTU) {
 225                 hard->offset[0] = 0;
 226                 hard->offset[1] = ofs = 512 - length;
 227         } else if (length > MTU) {
 228                 hard->offset[0] = 0;
 229                 hard->offset[1] = ofs = 512 - length - 3;
 230         } else {
 231                 hard->offset[0] = ofs = 256 - length;
 232         }
 233
 234         lp->hw.copy_to_card(dev, bufnum, 0, hard, ARC_HDR_SIZE);
 235         lp->hw.copy_to_card(dev, bufnum, ofs, &pkt->soft, length);
 236
 237         lp->lastload_dest = hard->dest;
 238
 239         return 1;               /* done */
 240 }