drivers/net/arcnet/capmode.c

   1 /*
   2  * Linux ARCnet driver - "cap mode" packet encapsulation.
   3  * It adds sequence numbers to packets for communicating between a user space
   4  * application and the driver. After a transmit it sends a packet with protocol
   5  * byte 0 back up to the userspace containing the sequence number of the packet
   6  * plus the transmit-status on the ArcNet.
   7  *
   8  * Written 2002-4 by Esben Nielsen, Vestas Wind Systems A/S
   9  * Derived from arc-rawmode.c by Avery Pennarun.
  10  * arc-rawmode was in turned based on skeleton.c, see below.
  11  *
  12  * **********************
  13  *
  14  * The original copyright of skeleton.c was as follows:
  15  *
  16  * skeleton.c Written 1993 by Donald Becker.
  17  * Copyright 1993 United States Government as represented by the
  18  * Director, National Security Agency.  This software may only be used
  19  * and distributed according to the terms of the GNU General Public License as
  20  * modified by SRC, incorporated herein by reference.
  21  *
  22  * **********************
  23  *
  24  * For more details, see drivers/net/arcnet.c
  25  *
  26  * **********************
  27  */
  28
  29 #define pr_fmt(fmt) "arcnet:" KBUILD_MODNAME ": " fmt
  30
  31 #include <linux/module.h>
  32 #include <linux/gfp.h>
  33 #include <linux/init.h>
  34 #include <linux/if_arp.h>
  35 #include <net/arp.h>
  36 #include <linux/netdevice.h>
  37 #include <linux/skbuff.h>
  38 #include <linux/arcdevice.h>
  39
  40 /* packet receiver */
  41 static void rx(struct net_device *dev, int bufnum,
  42                struct archdr *pkthdr, int length)
  43 {
  44         struct arcnet_local *lp = netdev_priv(dev);
  45         struct sk_buff *skb;
  46         struct archdr *pkt = pkthdr;
  47         char *pktbuf, *pkthdrbuf;
  48         int ofs;
  49
  50         arc_printk(D_DURING, dev, "it's a raw(cap) packet (length=%d)\n",
  51                    length);
  52
  53         if (length >= MinTU)
  54                 ofs = 512 - length;
  55         else
  56                 ofs = 256 - length;
  57
  58         skb = alloc_skb(length + ARC_HDR_SIZE + sizeof(int), GFP_ATOMIC);
  59         if (skb == NULL) {
  60                 dev->stats.rx_dropped++;
  61                 return;
  62         }
  63         skb_put(skb, length + ARC_HDR_SIZE + sizeof(int));
  64         skb->dev = dev;
  65         skb_reset_mac_header(skb);
  66         pkt = (struct archdr *)skb_mac_header(skb);
  67         skb_pull(skb, ARC_HDR_SIZE);
  68
  69         /* up to sizeof(pkt->soft) has already been copied from the card
  70          * squeeze in an int for the cap encapsulation
  71          * use these variables to be sure we count in bytes, not in
  72          * sizeof(struct archdr)
  73          */
  74         pktbuf = (char *)pkt;
  75         pkthdrbuf = (char *)pkthdr;
  76         memcpy(pktbuf, pkthdrbuf, ARC_HDR_SIZE + sizeof(pkt->soft.cap.proto));
  77         memcpy(pktbuf + ARC_HDR_SIZE + sizeof(pkt->soft.cap.proto) + sizeof(int),
  78                pkthdrbuf + ARC_HDR_SIZE + sizeof(pkt->soft.cap.proto),
  79                sizeof(struct archdr) - ARC_HDR_SIZE - sizeof(pkt->soft.cap.proto));
  80
  81         if (length > sizeof(pkt->soft))
  82                 lp->hw.copy_from_card(dev, bufnum, ofs + sizeof(pkt->soft),
  83                                       pkt->soft.raw + sizeof(pkt->soft)
  84                                       + sizeof(int),
  85                                       length - sizeof(pkt->soft));
  86
  87         if (BUGLVL(D_SKB))
  88                 arcnet_dump_skb(dev, skb, "rx");
  89
  90         skb->protocol = cpu_to_be16(ETH_P_ARCNET);
  91         netif_rx(skb);
  92 }
  93
  94 /* Create the ARCnet hard/soft headers for cap mode.
  95  * There aren't any soft headers in cap mode - not even the protocol id.
  96  */
  97 static int build_header(struct sk_buff *skb,
  98                         struct net_device *dev,
  99                         unsigned short type,
 100                         uint8_t daddr)
 101 {
 102         int hdr_size = ARC_HDR_SIZE;
 103         struct archdr *pkt = (struct archdr *)skb_push(skb, hdr_size);
 104
 105         arc_printk(D_PROTO, dev, "Preparing header for cap packet %x.\n",
 106                    *((int *)&pkt->soft.cap.cookie[0]));
 107
 108         /* Set the source hardware address.
 109          *
 110          * This is pretty pointless for most purposes, but it can help in
 111          * debugging.  ARCnet does not allow us to change the source address in
 112          * the actual packet sent)
 113          */
 114         pkt->hard.source = *dev->dev_addr;
 115
 116         /* see linux/net/ethernet/eth.c to see where I got the following */
 117
 118         if (dev->flags & (IFF_LOOPBACK | IFF_NOARP)) {
 119                 /* FIXME: fill in the last byte of the dest ipaddr here to
 120                  * better comply with RFC1051 in "noarp" mode.
 121                  */
 122                 pkt->hard.dest = 0;
 123                 return hdr_size;
 124         }
 125         /* otherwise, just fill it in and go! */
 126         pkt->hard.dest = daddr;
 127
 128         return hdr_size;        /* success */
 129 }
 130
 131 static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
 132                       int bufnum)
 133 {
 134         struct arcnet_local *lp = netdev_priv(dev);
 135         struct arc_hardware *hard = &pkt->hard;
 136         int ofs;
 137
 138         /* hard header is not included in packet length */
 139         length -= ARC_HDR_SIZE;
 140         /* And neither is the cookie field */
 141         length -= sizeof(int);
 142
 143         arc_printk(D_DURING, dev, "prepare_tx: txbufs=%d/%d/%d\n",
 144                    lp->next_tx, lp->cur_tx, bufnum);
 145
 146         arc_printk(D_PROTO, dev, "Sending for cap packet %x.\n",
 147                    *((int *)&pkt->soft.cap.cookie[0]));
 148
 149         if (length > XMTU) {
 150                 /* should never happen! other people already check for this. */
 151                 arc_printk(D_NORMAL, dev, "Bug!  prepare_tx with size %d (> %d)\n",
 152                            length, XMTU);
 153                 length = XMTU;
 154         }
 155         if (length > MinTU) {
 156                 hard->offset[0] = 0;
 157                 hard->offset[1] = ofs = 512 - length;
 158         } else if (length > MTU) {
 159                 hard->offset[0] = 0;
 160                 hard->offset[1] = ofs = 512 - length - 3;
 161         } else {
 162                 hard->offset[0] = ofs = 256 - length;
 163         }
 164
 165         arc_printk(D_DURING, dev, "prepare_tx: length=%d ofs=%d\n",
 166                    length, ofs);
 167
 168         /* Copy the arcnet-header + the protocol byte down: */
 169         lp->hw.copy_to_card(dev, bufnum, 0, hard, ARC_HDR_SIZE);
 170         lp->hw.copy_to_card(dev, bufnum, ofs, &pkt->soft.cap.proto,
 171                             sizeof(pkt->soft.cap.proto));
 172
 173         /* Skip the extra integer we have written into it as a cookie
 174          * but write the rest of the message:
 175          */
 176         lp->hw.copy_to_card(dev, bufnum, ofs + 1,
 177                             ((unsigned char *)&pkt->soft.cap.mes), length - 1);
 178
 179         lp->lastload_dest = hard->dest;
 180
 181         return 1;       /* done */
 182 }
 183
 184 static int ack_tx(struct net_device *dev, int acked)
 185 {
 186         struct arcnet_local *lp = netdev_priv(dev);
 187         struct sk_buff *ackskb;
 188         struct archdr *ackpkt;
 189         int length = sizeof(struct arc_cap);
 190
 191         arc_printk(D_DURING, dev, "capmode: ack_tx: protocol: %x: result: %d\n",
 192                    lp->outgoing.skb->protocol, acked);
 193
 194         if (BUGLVL(D_SKB))
 195                 arcnet_dump_skb(dev, lp->outgoing.skb, "ack_tx");
 196
 197         /* Now alloc a skb to send back up through the layers: */
 198         ackskb = alloc_skb(length + ARC_HDR_SIZE, GFP_ATOMIC);
 199         if (ackskb == NULL)
 200                 goto free_outskb;
 201
 202         skb_put(ackskb, length + ARC_HDR_SIZE);
 203         ackskb->dev = dev;
 204
 205         skb_reset_mac_header(ackskb);
 206         ackpkt = (struct archdr *)skb_mac_header(ackskb);
 207         /* skb_pull(ackskb, ARC_HDR_SIZE); */
 208
 209         skb_copy_from_linear_data(lp->outgoing.skb, ackpkt,
 210                                   ARC_HDR_SIZE + sizeof(struct arc_cap));
 211         ackpkt->soft.cap.proto = 0; /* using protocol 0 for acknowledge */
 212         ackpkt->soft.cap.mes.ack = acked;
 213
 214         arc_printk(D_PROTO, dev, "Ackknowledge for cap packet %x.\n",
 215                    *((int *)&ackpkt->soft.cap.cookie[0]));
 216
 217         ackskb->protocol = cpu_to_be16(ETH_P_ARCNET);
 218
 219         if (BUGLVL(D_SKB))
 220                 arcnet_dump_skb(dev, ackskb, "ack_tx_recv");
 221         netif_rx(ackskb);
 222
 223 free_outskb:
 224         dev_kfree_skb_irq(lp->outgoing.skb);
 225         lp->outgoing.proto = NULL; /* We are always finished when in this protocol */
 226
 227         return 0;
 228 }
 229
 230 static struct ArcProto capmode_proto = {
 231         'r',
 232         XMTU,
 233         0,
 234         rx,
 235         build_header,
 236         prepare_tx,
 237         NULL,
 238         ack_tx
 239 };
 240
 241 static void arcnet_cap_init(void)
 242 {
 243         int count;
 244
 245         for (count = 1; count <= 8; count++)
 246                 if (arc_proto_map[count] == arc_proto_default)
 247                         arc_proto_map[count] = &capmode_proto;
 248
 249         /* for cap mode, we only set the bcast proto if there's no better one */
 250         if (arc_bcast_proto == arc_proto_default)
 251                 arc_bcast_proto = &capmode_proto;
 252
 253         arc_proto_default = &capmode_proto;
 254         arc_raw_proto = &capmode_proto;
 255 }
 256
 257 static int __init capmode_module_init(void)
 258 {
 259         pr_info("%s\n", "cap mode (`c') encapsulation support loaded");
 260         arcnet_cap_init();
 261         return 0;
 262 }
 263
 264 static void __exit capmode_module_exit(void)
 265 {
 266         arcnet_unregister_proto(&capmode_proto);
 267 }
 268 module_init(capmode_module_init);
 269 module_exit(capmode_module_exit);
 270
 271 MODULE_LICENSE("GPL");