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
  27 #define pr_fmt(fmt) "arcnet:" KBUILD_MODNAME ": " fmt
  28
  29 #include <linux/module.h>
  30 #include <linux/gfp.h>
  31 #include <linux/init.h>
  32 #include <linux/if_arp.h>
  33 #include <net/arp.h>
  34 #include <linux/netdevice.h>
  35 #include <linux/skbuff.h>
  36
  37 #include "arcdevice.h"
  38
  39 static __be16 type_trans(struct sk_buff *skb, struct net_device *dev);
  40 static void rx(struct net_device *dev, int bufnum,
  41                struct archdr *pkthdr, int length);
  42 static int build_header(struct sk_buff *skb, struct net_device *dev,
  43                         unsigned short type, uint8_t daddr);
  44 static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
  45                       int bufnum);
  46
  47 static struct ArcProto rfc1051_proto = {
  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 static int __init arcnet_rfc1051_init(void)
  59 {
  60         pr_info("%s\n", "RFC1051 \"simple standard\" (`s') encapsulation support loaded");
  61
  62         arc_proto_map[ARC_P_IP_RFC1051]
  63             = arc_proto_map[ARC_P_ARP_RFC1051]
  64             = &rfc1051_proto;
  65
  66         /* if someone else already owns the broadcast, we won't take it */
  67         if (arc_bcast_proto == arc_proto_default)
  68                 arc_bcast_proto = &rfc1051_proto;
  69
  70         return 0;
  71 }
  72
  73 static void __exit arcnet_rfc1051_exit(void)
  74 {
  75         arcnet_unregister_proto(&rfc1051_proto);
  76 }
  77
  78 module_init(arcnet_rfc1051_init);
  79 module_exit(arcnet_rfc1051_exit);
  80
  81 MODULE_LICENSE("GPL");
  82
  83 /* Determine a packet's protocol ID.
  84  *
  85  * With ARCnet we have to convert everything to Ethernet-style stuff.
  86  */
  87 static __be16 type_trans(struct sk_buff *skb, struct net_device *dev)
  88 {
  89         struct archdr *pkt = (struct archdr *)skb->data;
  90         struct arc_rfc1051 *soft = &pkt->soft.rfc1051;
  91         int hdr_size = ARC_HDR_SIZE + RFC1051_HDR_SIZE;
  92
  93         /* Pull off the arcnet header. */
  94         skb_reset_mac_header(skb);
  95         skb_pull(skb, hdr_size);
  96
  97         if (pkt->hard.dest == 0) {
  98                 skb->pkt_type = PACKET_BROADCAST;
  99         } else if (dev->flags & IFF_PROMISC) {
 100                 /* if we're not sending to ourselves :) */
 101                 if (pkt->hard.dest != dev->dev_addr[0])
 102                         skb->pkt_type = PACKET_OTHERHOST;
 103         }
 104         /* now return the protocol number */
 105         switch (soft->proto) {
 106         case ARC_P_IP_RFC1051:
 107                 return htons(ETH_P_IP);
 108         case ARC_P_ARP_RFC1051:
 109                 return htons(ETH_P_ARP);
 110
 111         default:
 112                 dev->stats.rx_errors++;
 113                 dev->stats.rx_crc_errors++;
 114                 return 0;
 115         }
 116
 117         return htons(ETH_P_IP);
 118 }
 119
 120 /* packet receiver */
 121 static void rx(struct net_device *dev, int bufnum,
 122                struct archdr *pkthdr, int length)
 123 {
 124         struct arcnet_local *lp = netdev_priv(dev);
 125         struct sk_buff *skb;
 126         struct archdr *pkt = pkthdr;
 127         int ofs;
 128
 129         arc_printk(D_DURING, dev, "it's a raw packet (length=%d)\n", length);
 130
 131         if (length >= MinTU)
 132                 ofs = 512 - length;
 133         else
 134                 ofs = 256 - length;
 135
 136         skb = alloc_skb(length + ARC_HDR_SIZE, GFP_ATOMIC);
 137         if (!skb) {
 138                 dev->stats.rx_dropped++;
 139                 return;
 140         }
 141         skb_put(skb, length + ARC_HDR_SIZE);
 142         skb->dev = dev;
 143
 144         pkt = (struct archdr *)skb->data;
 145
 146         /* up to sizeof(pkt->soft) has already been copied from the card */
 147         memcpy(pkt, pkthdr, sizeof(struct archdr));
 148         if (length > sizeof(pkt->soft))
 149                 lp->hw.copy_from_card(dev, bufnum, ofs + sizeof(pkt->soft),
 150                                       pkt->soft.raw + sizeof(pkt->soft),
 151                                       length - sizeof(pkt->soft));
 152
 153         if (BUGLVL(D_SKB))
 154                 arcnet_dump_skb(dev, skb, "rx");
 155
 156         skb->protocol = type_trans(skb, dev);
 157         netif_rx(skb);
 158 }
 159
 160 /* Create the ARCnet hard/soft headers for RFC1051 */
 161 static int build_header(struct sk_buff *skb, struct net_device *dev,
 162                         unsigned short type, uint8_t daddr)
 163 {
 164         int hdr_size = ARC_HDR_SIZE + RFC1051_HDR_SIZE;
 165         struct archdr *pkt = skb_push(skb, hdr_size);
 166         struct arc_rfc1051 *soft = &pkt->soft.rfc1051;
 167
 168         /* set the protocol ID according to RFC1051 */
 169         switch (type) {
 170         case ETH_P_IP:
 171                 soft->proto = ARC_P_IP_RFC1051;
 172                 break;
 173         case ETH_P_ARP:
 174                 soft->proto = ARC_P_ARP_RFC1051;
 175                 break;
 176         default:
 177                 arc_printk(D_NORMAL, dev, "RFC1051: I don't understand protocol %d (%Xh)\n",
 178                            type, type);
 179                 dev->stats.tx_errors++;
 180                 dev->stats.tx_aborted_errors++;
 181                 return 0;
 182         }
 183
 184         /* Set the source hardware address.
 185          *
 186          * This is pretty pointless for most purposes, but it can help in
 187          * debugging.  ARCnet does not allow us to change the source address
 188          * in the actual packet sent.
 189          */
 190         pkt->hard.source = *dev->dev_addr;
 191
 192         /* see linux/net/ethernet/eth.c to see where I got the following */
 193
 194         if (dev->flags & (IFF_LOOPBACK | IFF_NOARP)) {
 195                 /* FIXME: fill in the last byte of the dest ipaddr here to
 196                  * better comply with RFC1051 in "noarp" mode.
 197                  */
 198                 pkt->hard.dest = 0;
 199                 return hdr_size;
 200         }
 201         /* otherwise, just fill it in and go! */
 202         pkt->hard.dest = daddr;
 203
 204         return hdr_size;        /* success */
 205 }
 206
 207 static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
 208                       int bufnum)
 209 {
 210         struct arcnet_local *lp = netdev_priv(dev);
 211         struct arc_hardware *hard = &pkt->hard;
 212         int ofs;
 213
 214         arc_printk(D_DURING, dev, "prepare_tx: txbufs=%d/%d/%d\n",
 215                    lp->next_tx, lp->cur_tx, bufnum);
 216
 217         /* hard header is not included in packet length */
 218         length -= ARC_HDR_SIZE;
 219
 220         if (length > XMTU) {
 221                 /* should never happen! other people already check for this. */
 222                 arc_printk(D_NORMAL, dev, "Bug!  prepare_tx with size %d (> %d)\n",
 223                            length, XMTU);
 224                 length = XMTU;
 225         }
 226         if (length > MinTU) {
 227                 hard->offset[0] = 0;
 228                 hard->offset[1] = ofs = 512 - length;
 229         } else if (length > MTU) {
 230                 hard->offset[0] = 0;
 231                 hard->offset[1] = ofs = 512 - length - 3;
 232         } else {
 233                 hard->offset[0] = ofs = 256 - length;
 234         }
 235
 236         lp->hw.copy_to_card(dev, bufnum, 0, hard, ARC_HDR_SIZE);
 237         lp->hw.copy_to_card(dev, bufnum, ofs, &pkt->soft, length);
 238
 239         lp->lastload_dest = hard->dest;
 240
 241         return 1;               /* done */
 242 }