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/gfp.h>
  29 #include <linux/init.h>
  30 #include <linux/if_arp.h>
  31 #include <net/arp.h>
  32 #include <linux/netdevice.h>
  33 #include <linux/skbuff.h>
  34 #include <linux/arcdevice.h>
  35
  36 #define VERSION "arcnet: raw mode (`r') encapsulation support loaded.\n"
  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         .suffix         = 'r',
  47         .mtu            = XMTU,
  48         .rx             = rx,
  49         .build_header   = build_header,
  50         .prepare_tx     = prepare_tx,
  51         .continue_tx    = NULL,
  52         .ack_tx         = NULL
  53 };
  54
  55 static int __init arcnet_raw_init(void)
  56 {
  57         int count;
  58
  59         printk(VERSION);
  60
  61         for (count = 0; count < 256; count++)
  62                 if (arc_proto_map[count] == arc_proto_default)
  63                         arc_proto_map[count] = &rawmode_proto;
  64
  65         /* for raw mode, we only set the bcast proto if there's no better one */
  66         if (arc_bcast_proto == arc_proto_default)
  67                 arc_bcast_proto = &rawmode_proto;
  68
  69         arc_proto_default = &rawmode_proto;
  70         return 0;
  71 }
  72
  73 static void __exit arcnet_raw_exit(void)
  74 {
  75         arcnet_unregister_proto(&rawmode_proto);
  76 }
  77
  78 module_init(arcnet_raw_init);
  79 module_exit(arcnet_raw_exit);
  80
  81 MODULE_LICENSE("GPL");
  82
  83 /* packet receiver */
  84 static void rx(struct net_device *dev, int bufnum,
  85                struct archdr *pkthdr, int length)
  86 {
  87         struct arcnet_local *lp = netdev_priv(dev);
  88         struct sk_buff *skb;
  89         struct archdr *pkt = pkthdr;
  90         int ofs;
  91
  92         BUGMSG(D_DURING, "it's a raw packet (length=%d)\n", length);
  93
  94         if (length > MTU)
  95                 ofs = 512 - length;
  96         else
  97                 ofs = 256 - length;
  98
  99         skb = alloc_skb(length + ARC_HDR_SIZE, GFP_ATOMIC);
 100         if (skb == NULL) {
 101                 BUGMSG(D_NORMAL, "Memory squeeze, dropping packet.\n");
 102                 dev->stats.rx_dropped++;
 103                 return;
 104         }
 105         skb_put(skb, length + ARC_HDR_SIZE);
 106         skb->dev = dev;
 107
 108         pkt = (struct archdr *)skb->data;
 109
 110         skb_reset_mac_header(skb);
 111         skb_pull(skb, ARC_HDR_SIZE);
 112
 113         /* up to sizeof(pkt->soft) has already been copied from the card */
 114         memcpy(pkt, pkthdr, sizeof(struct archdr));
 115         if (length > sizeof(pkt->soft))
 116                 lp->hw.copy_from_card(dev, bufnum, ofs + sizeof(pkt->soft),
 117                                       pkt->soft.raw + sizeof(pkt->soft),
 118                                       length - sizeof(pkt->soft));
 119
 120         if (BUGLVL(D_SKB))
 121                 arcnet_dump_skb(dev, skb, "rx");
 122
 123         skb->protocol = cpu_to_be16(ETH_P_ARCNET);
 124         netif_rx(skb);
 125 }
 126
 127 /* Create the ARCnet hard/soft headers for raw mode.
 128  * There aren't any soft headers in raw mode - not even the protocol id.
 129  */
 130 static int build_header(struct sk_buff *skb, struct net_device *dev,
 131                         unsigned short type, uint8_t daddr)
 132 {
 133         int hdr_size = ARC_HDR_SIZE;
 134         struct archdr *pkt = (struct archdr *)skb_push(skb, hdr_size);
 135
 136         /* Set the source hardware address.
 137          *
 138          * This is pretty pointless for most purposes, but it can help in
 139          * debugging.  ARCnet does not allow us to change the source address
 140          * in the actual packet sent.
 141          */
 142         pkt->hard.source = *dev->dev_addr;
 143
 144         /* see linux/net/ethernet/eth.c to see where I got the following */
 145
 146         if (dev->flags & (IFF_LOOPBACK | IFF_NOARP)) {
 147                 /* FIXME: fill in the last byte of the dest ipaddr here
 148                  * to better comply with RFC1051 in "noarp" mode.
 149                  */
 150                 pkt->hard.dest = 0;
 151                 return hdr_size;
 152         }
 153         /* otherwise, just fill it in and go! */
 154         pkt->hard.dest = daddr;
 155
 156         return hdr_size;        /* success */
 157 }
 158
 159 static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
 160                       int bufnum)
 161 {
 162         struct arcnet_local *lp = netdev_priv(dev);
 163         struct arc_hardware *hard = &pkt->hard;
 164         int ofs;
 165
 166         BUGMSG(D_DURING, "prepare_tx: txbufs=%d/%d/%d\n",
 167                lp->next_tx, lp->cur_tx, bufnum);
 168
 169         length -= ARC_HDR_SIZE; /* hard header is not included in packet length */
 170
 171         if (length > XMTU) {
 172                 /* should never happen! other people already check for this. */
 173                 BUGMSG(D_NORMAL, "Bug!  prepare_tx with size %d (> %d)\n",
 174                        length, XMTU);
 175                 length = XMTU;
 176         }
 177         if (length >= MinTU) {
 178                 hard->offset[0] = 0;
 179                 hard->offset[1] = ofs = 512 - length;
 180         } else if (length > MTU) {
 181                 hard->offset[0] = 0;
 182                 hard->offset[1] = ofs = 512 - length - 3;
 183         } else {
 184                 hard->offset[0] = ofs = 256 - length;
 185         }
 186
 187         BUGMSG(D_DURING, "prepare_tx: length=%d ofs=%d\n",
 188                length, ofs);
 189
 190         lp->hw.copy_to_card(dev, bufnum, 0, hard, ARC_HDR_SIZE);
 191         lp->hw.copy_to_card(dev, bufnum, ofs, &pkt->soft, length);
 192
 193         lp->lastload_dest = hard->dest;
 194
 195         return 1;               /* done */
 196 }