net/arcnet/rfc1051.c

0001 /*
0002  * Linux ARCnet driver - RFC1051 ("simple" standard) packet encapsulation
0003  *
0004  * Written 1994-1999 by Avery Pennarun.
0005  * Derived from skeleton.c by Donald Becker.
0006  *
0007  * Special thanks to Contemporary Controls, Inc. (www.ccontrols.com)
0008  *  for sponsoring the further development of this driver.
0009  *
0010  * **********************
0011  *
0012  * The original copyright of skeleton.c was as follows:
0013  *
0014  * skeleton.c Written 1993 by Donald Becker.
0015  * Copyright 1993 United States Government as represented by the
0016  * Director, National Security Agency.  This software may only be used
0017  * and distributed according to the terms of the GNU General Public License as
0018  * modified by SRC, incorporated herein by reference.
0019  *
0020  * **********************
0021  *
0022  * For more details, see drivers/net/arcnet.c
0023  *
0024  * **********************
0025  */
0026
0027 #define pr_fmt(fmt) "arcnet:" KBUILD_MODNAME ": " fmt
0028
0029 #include <linux/module.h>
0030 #include <linux/gfp.h>
0031 #include <linux/init.h>
0032 #include <linux/if_arp.h>
0033 #include <net/arp.h>
0034 #include <linux/netdevice.h>
0035 #include <linux/skbuff.h>
0036
0037 #include "arcdevice.h"
0038
0039 static __be16 type_trans(struct sk_buff *skb, struct net_device *dev);
0040 static void rx(struct net_device *dev, int bufnum,
0041            struct archdr *pkthdr, int length);
0042 static int build_header(struct sk_buff *skb, struct net_device *dev,
0043             unsigned short type, uint8_t daddr);
0044 static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
0045               int bufnum);
0046
0047 static struct ArcProto rfc1051_proto = {
0048     .suffix     = 's',
0049     .mtu        = XMTU - RFC1051_HDR_SIZE,
0050     .is_ip          = 1,
0051     .rx     = rx,
0052     .build_header   = build_header,
0053     .prepare_tx = prepare_tx,
0054     .continue_tx    = NULL,
0055     .ack_tx         = NULL
0056 };
0057
0058 static int __init arcnet_rfc1051_init(void)
0059 {
0060     pr_info("%s\n", "RFC1051 \"simple standard\" (`s') encapsulation support loaded");
0061
0062     arc_proto_map[ARC_P_IP_RFC1051]
0063         = arc_proto_map[ARC_P_ARP_RFC1051]
0064         = &rfc1051_proto;
0065
0066     /* if someone else already owns the broadcast, we won't take it */
0067     if (arc_bcast_proto == arc_proto_default)
0068         arc_bcast_proto = &rfc1051_proto;
0069
0070     return 0;
0071 }
0072
0073 static void __exit arcnet_rfc1051_exit(void)
0074 {
0075     arcnet_unregister_proto(&rfc1051_proto);
0076 }
0077
0078 module_init(arcnet_rfc1051_init);
0079 module_exit(arcnet_rfc1051_exit);
0080
0081 MODULE_LICENSE("GPL");
0082
0083 /* Determine a packet's protocol ID.
0084  *
0085  * With ARCnet we have to convert everything to Ethernet-style stuff.
0086  */
0087 static __be16 type_trans(struct sk_buff *skb, struct net_device *dev)
0088 {
0089     struct archdr *pkt = (struct archdr *)skb->data;
0090     struct arc_rfc1051 *soft = &pkt->soft.rfc1051;
0091     int hdr_size = ARC_HDR_SIZE + RFC1051_HDR_SIZE;
0092
0093     /* Pull off the arcnet header. */
0094     skb_reset_mac_header(skb);
0095     skb_pull(skb, hdr_size);
0096
0097     if (pkt->hard.dest == 0) {
0098         skb->pkt_type = PACKET_BROADCAST;
0099     } else if (dev->flags & IFF_PROMISC) {
0100         /* if we're not sending to ourselves :) */
0101         if (pkt->hard.dest != dev->dev_addr[0])
0102             skb->pkt_type = PACKET_OTHERHOST;
0103     }
0104     /* now return the protocol number */
0105     switch (soft->proto) {
0106     case ARC_P_IP_RFC1051:
0107         return htons(ETH_P_IP);
0108     case ARC_P_ARP_RFC1051:
0109         return htons(ETH_P_ARP);
0110
0111     default:
0112         dev->stats.rx_errors++;
0113         dev->stats.rx_crc_errors++;
0114         return 0;
0115     }
0116
0117     return htons(ETH_P_IP);
0118 }
0119
0120 /* packet receiver */
0121 static void rx(struct net_device *dev, int bufnum,
0122            struct archdr *pkthdr, int length)
0123 {
0124     struct arcnet_local *lp = netdev_priv(dev);
0125     struct sk_buff *skb;
0126     struct archdr *pkt = pkthdr;
0127     int ofs;
0128
0129     arc_printk(D_DURING, dev, "it's a raw packet (length=%d)\n", length);
0130
0131     if (length >= MinTU)
0132         ofs = 512 - length;
0133     else
0134         ofs = 256 - length;
0135
0136     skb = alloc_skb(length + ARC_HDR_SIZE, GFP_ATOMIC);
0137     if (!skb) {
0138         dev->stats.rx_dropped++;
0139         return;
0140     }
0141     skb_put(skb, length + ARC_HDR_SIZE);
0142     skb->dev = dev;
0143
0144     pkt = (struct archdr *)skb->data;
0145
0146     /* up to sizeof(pkt->soft) has already been copied from the card */
0147     memcpy(pkt, pkthdr, sizeof(struct archdr));
0148     if (length > sizeof(pkt->soft))
0149         lp->hw.copy_from_card(dev, bufnum, ofs + sizeof(pkt->soft),
0150                       pkt->soft.raw + sizeof(pkt->soft),
0151                       length - sizeof(pkt->soft));
0152
0153     if (BUGLVL(D_SKB))
0154         arcnet_dump_skb(dev, skb, "rx");
0155
0156     skb->protocol = type_trans(skb, dev);
0157     netif_rx(skb);
0158 }
0159
0160 /* Create the ARCnet hard/soft headers for RFC1051 */
0161 static int build_header(struct sk_buff *skb, struct net_device *dev,
0162             unsigned short type, uint8_t daddr)
0163 {
0164     int hdr_size = ARC_HDR_SIZE + RFC1051_HDR_SIZE;
0165     struct archdr *pkt = skb_push(skb, hdr_size);
0166     struct arc_rfc1051 *soft = &pkt->soft.rfc1051;
0167
0168     /* set the protocol ID according to RFC1051 */
0169     switch (type) {
0170     case ETH_P_IP:
0171         soft->proto = ARC_P_IP_RFC1051;
0172         break;
0173     case ETH_P_ARP:
0174         soft->proto = ARC_P_ARP_RFC1051;
0175         break;
0176     default:
0177         arc_printk(D_NORMAL, dev, "RFC1051: I don't understand protocol %d (%Xh)\n",
0178                type, type);
0179         dev->stats.tx_errors++;
0180         dev->stats.tx_aborted_errors++;
0181         return 0;
0182     }
0183
0184     /* Set the source hardware address.
0185      *
0186      * This is pretty pointless for most purposes, but it can help in
0187      * debugging.  ARCnet does not allow us to change the source address
0188      * in the actual packet sent.
0189      */
0190     pkt->hard.source = *dev->dev_addr;
0191
0192     /* see linux/net/ethernet/eth.c to see where I got the following */
0193
0194     if (dev->flags & (IFF_LOOPBACK | IFF_NOARP)) {
0195         /* FIXME: fill in the last byte of the dest ipaddr here to
0196          * better comply with RFC1051 in "noarp" mode.
0197          */
0198         pkt->hard.dest = 0;
0199         return hdr_size;
0200     }
0201     /* otherwise, just fill it in and go! */
0202     pkt->hard.dest = daddr;
0203
0204     return hdr_size;    /* success */
0205 }
0206
0207 static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
0208               int bufnum)
0209 {
0210     struct arcnet_local *lp = netdev_priv(dev);
0211     struct arc_hardware *hard = &pkt->hard;
0212     int ofs;
0213
0214     arc_printk(D_DURING, dev, "prepare_tx: txbufs=%d/%d/%d\n",
0215            lp->next_tx, lp->cur_tx, bufnum);
0216
0217     /* hard header is not included in packet length */
0218     length -= ARC_HDR_SIZE;
0219
0220     if (length > XMTU) {
0221         /* should never happen! other people already check for this. */
0222         arc_printk(D_NORMAL, dev, "Bug!  prepare_tx with size %d (> %d)\n",
0223                length, XMTU);
0224         length = XMTU;
0225     }
0226     if (length > MinTU) {
0227         hard->offset[0] = 0;
0228         hard->offset[1] = ofs = 512 - length;
0229     } else if (length > MTU) {
0230         hard->offset[0] = 0;
0231         hard->offset[1] = ofs = 512 - length - 3;
0232     } else {
0233         hard->offset[0] = ofs = 256 - length;
0234     }
0235
0236     lp->hw.copy_to_card(dev, bufnum, 0, hard, ARC_HDR_SIZE);
0237     lp->hw.copy_to_card(dev, bufnum, ofs, &pkt->soft, length);
0238
0239     lp->lastload_dest = hard->dest;
0240
0241     return 1;       /* done */
0242 }