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 arcnet_local *lp = netdev_priv(dev);
  92         struct archdr *pkt = (struct archdr *) skb->data;
  93         struct arc_rfc1051 *soft = &pkt->soft.rfc1051;
  94         int hdr_size = ARC_HDR_SIZE + RFC1051_HDR_SIZE;
  95
  96         /* Pull off the arcnet header. */
  97         skb_reset_mac_header(skb);
  98         skb_pull(skb, hdr_size);
  99
 100         if (pkt->hard.dest == 0)
 101                 skb->pkt_type = PACKET_BROADCAST;
 102         else if (dev->flags & IFF_PROMISC) {
 103                 /* if we're not sending to ourselves :) */
 104                 if (pkt->hard.dest != dev->dev_addr[0])
 105                         skb->pkt_type = PACKET_OTHERHOST;
 106         }
 107         /* now return the protocol number */
 108         switch (soft->proto) {
 109         case ARC_P_IP_RFC1051:
 110                 return htons(ETH_P_IP);
 111         case ARC_P_ARP_RFC1051:
 112                 return htons(ETH_P_ARP);
 113
 114         default:
 115                 lp->stats.rx_errors++;
 116                 lp->stats.rx_crc_errors++;
 117                 return 0;
 118         }
 119
 120         return htons(ETH_P_IP);
 121 }
 122
 123
 124 /* packet receiver */
 125 static void rx(struct net_device *dev, int bufnum,
 126                struct archdr *pkthdr, int length)
 127 {
 128         struct arcnet_local *lp = netdev_priv(dev);
 129         struct sk_buff *skb;
 130         struct archdr *pkt = pkthdr;
 131         int ofs;
 132
 133         BUGMSG(D_DURING, "it's a raw packet (length=%d)\n", length);
 134
 135         if (length >= MinTU)
 136                 ofs = 512 - length;
 137         else
 138                 ofs = 256 - length;
 139
 140         skb = alloc_skb(length + ARC_HDR_SIZE, GFP_ATOMIC);
 141         if (skb == NULL) {
 142                 BUGMSG(D_NORMAL, "Memory squeeze, dropping packet.\n");
 143                 lp->stats.rx_dropped++;
 144                 return;
 145         }
 146         skb_put(skb, length + ARC_HDR_SIZE);
 147         skb->dev = dev;
 148
 149         pkt = (struct archdr *) skb->data;
 150
 151         /* up to sizeof(pkt->soft) has already been copied from the card */
 152         memcpy(pkt, pkthdr, sizeof(struct archdr));
 153         if (length > sizeof(pkt->soft))
 154                 lp->hw.copy_from_card(dev, bufnum, ofs + sizeof(pkt->soft),
 155                                       pkt->soft.raw + sizeof(pkt->soft),
 156                                       length - sizeof(pkt->soft));
 157
 158         BUGLVL(D_SKB) arcnet_dump_skb(dev, skb, "rx");
 159
 160         skb->protocol = type_trans(skb, dev);
 161         netif_rx(skb);
 162 }
 163
 164
 165 /*
 166  * Create the ARCnet hard/soft headers for RFC1051.
 167  */
 168 static int build_header(struct sk_buff *skb, struct net_device *dev,
 169                         unsigned short type, uint8_t daddr)
 170 {
 171         struct arcnet_local *lp = netdev_priv(dev);
 172         int hdr_size = ARC_HDR_SIZE + RFC1051_HDR_SIZE;
 173         struct archdr *pkt = (struct archdr *) skb_push(skb, hdr_size);
 174         struct arc_rfc1051 *soft = &pkt->soft.rfc1051;
 175
 176         /* set the protocol ID according to RFC1051 */
 177         switch (type) {
 178         case ETH_P_IP:
 179                 soft->proto = ARC_P_IP_RFC1051;
 180                 break;
 181         case ETH_P_ARP:
 182                 soft->proto = ARC_P_ARP_RFC1051;
 183                 break;
 184         default:
 185                 BUGMSG(D_NORMAL, "RFC1051: I don't understand protocol %d (%Xh)\n",
 186                        type, type);
 187                 lp->stats.tx_errors++;
 188                 lp->stats.tx_aborted_errors++;
 189                 return 0;
 190         }
 191
 192
 193         /*
 194          * Set the source hardware address.
 195          *
 196          * This is pretty pointless for most purposes, but it can help in
 197          * debugging.  ARCnet does not allow us to change the source address in
 198          * the actual packet sent)
 199          */
 200         pkt->hard.source = *dev->dev_addr;
 201
 202         /* see linux/net/ethernet/eth.c to see where I got the following */
 203
 204         if (dev->flags & (IFF_LOOPBACK | IFF_NOARP)) {
 205                 /*
 206                  * FIXME: fill in the last byte of the dest ipaddr here to better
 207                  * comply with RFC1051 in "noarp" mode.
 208                  */
 209                 pkt->hard.dest = 0;
 210                 return hdr_size;
 211         }
 212         /* otherwise, just fill it in and go! */
 213         pkt->hard.dest = daddr;
 214
 215         return hdr_size;        /* success */
 216 }
 217
 218
 219 static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
 220                       int bufnum)
 221 {
 222         struct arcnet_local *lp = netdev_priv(dev);
 223         struct arc_hardware *hard = &pkt->hard;
 224         int ofs;
 225
 226         BUGMSG(D_DURING, "prepare_tx: txbufs=%d/%d/%d\n",
 227                lp->next_tx, lp->cur_tx, bufnum);
 228
 229         length -= ARC_HDR_SIZE; /* hard header is not included in packet length */
 230
 231         if (length > XMTU) {
 232                 /* should never happen! other people already check for this. */
 233                 BUGMSG(D_NORMAL, "Bug!  prepare_tx with size %d (> %d)\n",
 234                        length, XMTU);
 235                 length = XMTU;
 236         }
 237         if (length > MinTU) {
 238                 hard->offset[0] = 0;
 239                 hard->offset[1] = ofs = 512 - length;
 240         } else if (length > MTU) {
 241                 hard->offset[0] = 0;
 242                 hard->offset[1] = ofs = 512 - length - 3;
 243         } else
 244                 hard->offset[0] = ofs = 256 - length;
 245
 246         lp->hw.copy_to_card(dev, bufnum, 0, hard, ARC_HDR_SIZE);
 247         lp->hw.copy_to_card(dev, bufnum, ofs, &pkt->soft, length);
 248
 249         lp->lastload_dest = hard->dest;
 250
 251         return 1;               /* done */
 252 }