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/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: raw mode (`r') encapsulation support loaded.\n"
  36
  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
  57 static int __init arcnet_raw_init(void)
  58 {
  59         int count;
  60
  61         printk(VERSION);
  62
  63         for (count = 0; count < 256; count++)
  64                 if (arc_proto_map[count] == arc_proto_default)
  65                         arc_proto_map[count] = &rawmode_proto;
  66
  67         /* for raw mode, we only set the bcast proto if there's no better one */
  68         if (arc_bcast_proto == arc_proto_default)
  69                 arc_bcast_proto = &rawmode_proto;
  70
  71         arc_proto_default = &rawmode_proto;
  72         return 0;
  73 }
  74
  75 static void __exit arcnet_raw_exit(void)
  76 {
  77         arcnet_unregister_proto(&rawmode_proto);
  78 }
  79
  80 module_init(arcnet_raw_init);
  81 module_exit(arcnet_raw_exit);
  82
  83 MODULE_LICENSE("GPL");
  84
  85
  86 /* packet receiver */
  87 static void rx(struct net_device *dev, int bufnum,
  88                struct archdr *pkthdr, int length)
  89 {
  90         struct arcnet_local *lp = netdev_priv(dev);
  91         struct sk_buff *skb;
  92         struct archdr *pkt = pkthdr;
  93         int ofs;
  94
  95         BUGMSG(D_DURING, "it's a raw packet (length=%d)\n", length);
  96
  97         if (length > MTU)
  98                 ofs = 512 - length;
  99         else
 100                 ofs = 256 - length;
 101
 102         skb = alloc_skb(length + ARC_HDR_SIZE, GFP_ATOMIC);
 103         if (skb == NULL) {
 104                 BUGMSG(D_NORMAL, "Memory squeeze, dropping packet.\n");
 105                 dev->stats.rx_dropped++;
 106                 return;
 107         }
 108         skb_put(skb, length + ARC_HDR_SIZE);
 109         skb->dev = dev;
 110
 111         pkt = (struct archdr *) skb->data;
 112
 113         skb_reset_mac_header(skb);
 114         skb_pull(skb, ARC_HDR_SIZE);
 115
 116         /* up to sizeof(pkt->soft) has already been copied from the card */
 117         memcpy(pkt, pkthdr, sizeof(struct archdr));
 118         if (length > sizeof(pkt->soft))
 119                 lp->hw.copy_from_card(dev, bufnum, ofs + sizeof(pkt->soft),
 120                                       pkt->soft.raw + sizeof(pkt->soft),
 121                                       length - sizeof(pkt->soft));
 122
 123         BUGLVL(D_SKB) arcnet_dump_skb(dev, skb, "rx");
 124
 125         skb->protocol = cpu_to_be16(ETH_P_ARCNET);
 126         netif_rx(skb);
 127 }
 128
 129
 130 /*
 131  * Create the ARCnet hard/soft headers for raw mode.
 132  * There aren't any soft headers in raw mode - not even the protocol id.
 133  */
 134 static int build_header(struct sk_buff *skb, struct net_device *dev,
 135                         unsigned short type, uint8_t daddr)
 136 {
 137         int hdr_size = ARC_HDR_SIZE;
 138         struct archdr *pkt = (struct archdr *) skb_push(skb, hdr_size);
 139
 140         /*
 141          * Set the source hardware address.
 142          *
 143          * This is pretty pointless for most purposes, but it can help in
 144          * debugging.  ARCnet does not allow us to change the source address in
 145          * the actual packet sent)
 146          */
 147         pkt->hard.source = *dev->dev_addr;
 148
 149         /* see linux/net/ethernet/eth.c to see where I got the following */
 150
 151         if (dev->flags & (IFF_LOOPBACK | IFF_NOARP)) {
 152                 /*
 153                  * FIXME: fill in the last byte of the dest ipaddr here to better
 154                  * comply with RFC1051 in "noarp" mode.
 155                  */
 156                 pkt->hard.dest = 0;
 157                 return hdr_size;
 158         }
 159         /* otherwise, just fill it in and go! */
 160         pkt->hard.dest = daddr;
 161
 162         return hdr_size;        /* success */
 163 }
 164
 165
 166 static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
 167                       int bufnum)
 168 {
 169         struct arcnet_local *lp = netdev_priv(dev);
 170         struct arc_hardware *hard = &pkt->hard;
 171         int ofs;
 172
 173         BUGMSG(D_DURING, "prepare_tx: txbufs=%d/%d/%d\n",
 174                lp->next_tx, lp->cur_tx, bufnum);
 175
 176         length -= ARC_HDR_SIZE; /* hard header is not included in packet length */
 177
 178         if (length > XMTU) {
 179                 /* should never happen! other people already check for this. */
 180                 BUGMSG(D_NORMAL, "Bug!  prepare_tx with size %d (> %d)\n",
 181                        length, XMTU);
 182                 length = XMTU;
 183         }
 184         if (length >= MinTU) {
 185                 hard->offset[0] = 0;
 186                 hard->offset[1] = ofs = 512 - length;
 187         } else if (length > MTU) {
 188                 hard->offset[0] = 0;
 189                 hard->offset[1] = ofs = 512 - length - 3;
 190         } else
 191                 hard->offset[0] = ofs = 256 - length;
 192
 193         BUGMSG(D_DURING, "prepare_tx: length=%d ofs=%d\n",
 194                length,ofs);
 195
 196         lp->hw.copy_to_card(dev, bufnum, 0, hard, ARC_HDR_SIZE);
 197         lp->hw.copy_to_card(dev, bufnum, ofs, &pkt->soft, length);
 198
 199         lp->lastload_dest = hard->dest;
 200
 201         return 1;               /* done */
 202 }