net/arcnet/arc-rawmode.c

0001 /*
0002  * Linux ARCnet driver - "raw mode" packet encapsulation (no soft headers)
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 #include "arcdevice.h"
0037
0038 /* packet receiver */
0039 static void rx(struct net_device *dev, int bufnum,
0040            struct archdr *pkthdr, int length)
0041 {
0042     struct arcnet_local *lp = netdev_priv(dev);
0043     struct sk_buff *skb;
0044     struct archdr *pkt = pkthdr;
0045     int ofs;
0046
0047     arc_printk(D_DURING, dev, "it's a raw packet (length=%d)\n", length);
0048
0049     if (length > MTU)
0050         ofs = 512 - length;
0051     else
0052         ofs = 256 - length;
0053
0054     skb = alloc_skb(length + ARC_HDR_SIZE, GFP_ATOMIC);
0055     if (!skb) {
0056         dev->stats.rx_dropped++;
0057         return;
0058     }
0059     skb_put(skb, length + ARC_HDR_SIZE);
0060     skb->dev = dev;
0061
0062     pkt = (struct archdr *)skb->data;
0063
0064     skb_reset_mac_header(skb);
0065     skb_pull(skb, ARC_HDR_SIZE);
0066
0067     /* up to sizeof(pkt->soft) has already been copied from the card */
0068     memcpy(pkt, pkthdr, sizeof(struct archdr));
0069     if (length > sizeof(pkt->soft))
0070         lp->hw.copy_from_card(dev, bufnum, ofs + sizeof(pkt->soft),
0071                       pkt->soft.raw + sizeof(pkt->soft),
0072                       length - sizeof(pkt->soft));
0073
0074     if (BUGLVL(D_SKB))
0075         arcnet_dump_skb(dev, skb, "rx");
0076
0077     skb->protocol = cpu_to_be16(ETH_P_ARCNET);
0078     netif_rx(skb);
0079 }
0080
0081 /* Create the ARCnet hard/soft headers for raw mode.
0082  * There aren't any soft headers in raw mode - not even the protocol id.
0083  */
0084 static int build_header(struct sk_buff *skb, struct net_device *dev,
0085             unsigned short type, uint8_t daddr)
0086 {
0087     int hdr_size = ARC_HDR_SIZE;
0088     struct archdr *pkt = skb_push(skb, hdr_size);
0089
0090     /* Set the source hardware address.
0091      *
0092      * This is pretty pointless for most purposes, but it can help in
0093      * debugging.  ARCnet does not allow us to change the source address
0094      * in the actual packet sent.
0095      */
0096     pkt->hard.source = *dev->dev_addr;
0097
0098     /* see linux/net/ethernet/eth.c to see where I got the following */
0099
0100     if (dev->flags & (IFF_LOOPBACK | IFF_NOARP)) {
0101         /* FIXME: fill in the last byte of the dest ipaddr here
0102          * to better comply with RFC1051 in "noarp" mode.
0103          */
0104         pkt->hard.dest = 0;
0105         return hdr_size;
0106     }
0107     /* otherwise, just fill it in and go! */
0108     pkt->hard.dest = daddr;
0109
0110     return hdr_size;    /* success */
0111 }
0112
0113 static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,
0114               int bufnum)
0115 {
0116     struct arcnet_local *lp = netdev_priv(dev);
0117     struct arc_hardware *hard = &pkt->hard;
0118     int ofs;
0119
0120     arc_printk(D_DURING, dev, "prepare_tx: txbufs=%d/%d/%d\n",
0121            lp->next_tx, lp->cur_tx, bufnum);
0122
0123     /* hard header is not included in packet length */
0124     length -= ARC_HDR_SIZE;
0125
0126     if (length > XMTU) {
0127         /* should never happen! other people already check for this. */
0128         arc_printk(D_NORMAL, dev, "Bug!  prepare_tx with size %d (> %d)\n",
0129                length, XMTU);
0130         length = XMTU;
0131     }
0132     if (length >= MinTU) {
0133         hard->offset[0] = 0;
0134         hard->offset[1] = ofs = 512 - length;
0135     } else if (length > MTU) {
0136         hard->offset[0] = 0;
0137         hard->offset[1] = ofs = 512 - length - 3;
0138     } else {
0139         hard->offset[0] = ofs = 256 - length;
0140     }
0141
0142     arc_printk(D_DURING, dev, "prepare_tx: length=%d ofs=%d\n",
0143            length, ofs);
0144
0145     lp->hw.copy_to_card(dev, bufnum, 0, hard, ARC_HDR_SIZE);
0146     lp->hw.copy_to_card(dev, bufnum, ofs, &pkt->soft, length);
0147
0148     lp->lastload_dest = hard->dest;
0149
0150     return 1;       /* done */
0151 }
0152
0153 static struct ArcProto rawmode_proto = {
0154     .suffix     = 'r',
0155     .mtu        = XMTU,
0156     .rx     = rx,
0157     .build_header   = build_header,
0158     .prepare_tx = prepare_tx,
0159     .continue_tx    = NULL,
0160     .ack_tx         = NULL
0161 };
0162
0163 static int __init arcnet_raw_init(void)
0164 {
0165     int count;
0166
0167     pr_info("raw mode (`r') encapsulation support loaded\n");
0168
0169     for (count = 0; count < 256; count++)
0170         if (arc_proto_map[count] == arc_proto_default)
0171             arc_proto_map[count] = &rawmode_proto;
0172
0173     /* for raw mode, we only set the bcast proto if there's no better one */
0174     if (arc_bcast_proto == arc_proto_default)
0175         arc_bcast_proto = &rawmode_proto;
0176
0177     arc_proto_default = &rawmode_proto;
0178     return 0;
0179 }
0180
0181 static void __exit arcnet_raw_exit(void)
0182 {
0183     arcnet_unregister_proto(&rawmode_proto);
0184 }
0185
0186 module_init(arcnet_raw_init);
0187 module_exit(arcnet_raw_exit);
0188
0189 MODULE_LICENSE("GPL");