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/*

 * Linux ARCnet driver - RFC1051 ("simple" standard) packet encapsulation

 *

 * Written 1994-1999 by Avery Pennarun.

 * Derived from skeleton.c by Donald Becker.

 *

 * Special thanks to Contemporary Controls, Inc. (www.ccontrols.com)

 *  for sponsoring the further development of this driver.

 *

 * **********************

 *

 * The original copyright of skeleton.c was as follows:

 *

 * skeleton.c Written 1993 by Donald Becker.

 * Copyright 1993 United States Government as represented by the

 * Director, National Security Agency.  This software may only be used

 * and distributed according to the terms of the GNU General Public License as

 * modified by SRC, incorporated herein by reference.

 *

 * **********************

 *

 * For more details, see drivers/net/arcnet.c

 *

 * **********************

 */

#include <linux/module.h>

#include <linux/init.h>

#include <linux/if_arp.h>

#include <net/arp.h>

#include <linux/netdevice.h>

#include <linux/skbuff.h>

#include <linux/arcdevice.h>

#define VERSION "arcnet: RFC1051 \"simple standard\" (`s') encapsulation support loaded.\n"

static __be16 type_trans(struct sk_buff *skb, struct net_device *dev);

static void rx(struct net_device *dev, int bufnum,

               struct archdr *pkthdr, int length);

static int build_header(struct sk_buff *skb, struct net_device *dev,

                        unsigned short type, uint8_t daddr);

static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,

                      int bufnum);

static struct ArcProto rfc1051_proto =

{

        .suffix         = 's',

        .mtu            = XMTU - RFC1051_HDR_SIZE,

        .is_ip          = 1,

        .rx             = rx,

        .build_header   = build_header,

        .prepare_tx     = prepare_tx,

        .continue_tx    = NULL,

        .ack_tx         = NULL

};

static int __init arcnet_rfc1051_init(void)

{

        printk(VERSION);

        arc_proto_map[ARC_P_IP_RFC1051]

            = arc_proto_map[ARC_P_ARP_RFC1051]

            = &rfc1051_proto;

        /* if someone else already owns the broadcast, we won't take it */

        if (arc_bcast_proto == arc_proto_default)

                arc_bcast_proto = &rfc1051_proto;

        return 0;

}

static void __exit arcnet_rfc1051_exit(void)

{

        arcnet_unregister_proto(&rfc1051_proto);

}

module_init(arcnet_rfc1051_init);

module_exit(arcnet_rfc1051_exit);

MODULE_LICENSE("GPL");

/*

 * Determine a packet's protocol ID.

 *

 * With ARCnet we have to convert everything to Ethernet-style stuff.

 */

static __be16 type_trans(struct sk_buff *skb, struct net_device *dev)

{

        struct arcnet_local *lp = dev->priv;

        struct archdr *pkt = (struct archdr *) skb->data;

        struct arc_rfc1051 *soft = &pkt->soft.rfc1051;

        int hdr_size = ARC_HDR_SIZE + RFC1051_HDR_SIZE;

        /* Pull off the arcnet header. */

        skb_reset_mac_header(skb);

        skb_pull(skb, hdr_size);

        if (pkt->hard.dest == 0)

                skb->pkt_type = PACKET_BROADCAST;

        else if (dev->flags & IFF_PROMISC) {

                /* if we're not sending to ourselves :) */

                if (pkt->hard.dest != dev->dev_addr[0])

                        skb->pkt_type = PACKET_OTHERHOST;

        }

        /* now return the protocol number */

        switch (soft->proto) {

        case ARC_P_IP_RFC1051:

                return htons(ETH_P_IP);

        case ARC_P_ARP_RFC1051:

                return htons(ETH_P_ARP);

        default:

                lp->stats.rx_errors++;

                lp->stats.rx_crc_errors++;

                return 0;

        }

        return htons(ETH_P_IP);

}

/* packet receiver */

static void rx(struct net_device *dev, int bufnum,

               struct archdr *pkthdr, int length)

{

        struct arcnet_local *lp = dev->priv;

        struct sk_buff *skb;

        struct archdr *pkt = pkthdr;

        int ofs;

        BUGMSG(D_DURING, "it's a raw packet (length=%d)\n", length);

        if (length >= MinTU)

                ofs = 512 - length;

        else

                ofs = 256 - length;

        skb = alloc_skb(length + ARC_HDR_SIZE, GFP_ATOMIC);

        if (skb == NULL) {

                BUGMSG(D_NORMAL, "Memory squeeze, dropping packet.\n");

                lp->stats.rx_dropped++;

                return;

        }

        skb_put(skb, length + ARC_HDR_SIZE);

        skb->dev = dev;

        pkt = (struct archdr *) skb->data;

        /* up to sizeof(pkt->soft) has already been copied from the card */

        memcpy(pkt, pkthdr, sizeof(struct archdr));

        if (length > sizeof(pkt->soft))

                lp->hw.copy_from_card(dev, bufnum, ofs + sizeof(pkt->soft),

                                      pkt->soft.raw + sizeof(pkt->soft),

                                      length - sizeof(pkt->soft));

        BUGLVL(D_SKB) arcnet_dump_skb(dev, skb, "rx");

        skb->protocol = type_trans(skb, dev);

        netif_rx(skb);

        dev->last_rx = jiffies;

}

/*

 * Create the ARCnet hard/soft headers for RFC1051.

 */

static int build_header(struct sk_buff *skb, struct net_device *dev,

                        unsigned short type, uint8_t daddr)

{

        struct arcnet_local *lp = dev->priv;

        int hdr_size = ARC_HDR_SIZE + RFC1051_HDR_SIZE;

        struct archdr *pkt = (struct archdr *) skb_push(skb, hdr_size);

        struct arc_rfc1051 *soft = &pkt->soft.rfc1051;

        /* set the protocol ID according to RFC1051 */

        switch (type) {

        case ETH_P_IP:

                soft->proto = ARC_P_IP_RFC1051;

                break;

        case ETH_P_ARP:

                soft->proto = ARC_P_ARP_RFC1051;

                break;

        default:

                BUGMSG(D_NORMAL, "RFC1051: I don't understand protocol %d (%Xh)\n",

                       type, type);

                lp->stats.tx_errors++;

                lp->stats.tx_aborted_errors++;

                return 0;

        }

        /*

         * Set the source hardware address.

         *

         * This is pretty pointless for most purposes, but it can help in

         * debugging.  ARCnet does not allow us to change the source address in

         * the actual packet sent)

         */

        pkt->hard.source = *dev->dev_addr;

        /* see linux/net/ethernet/eth.c to see where I got the following */

        if (dev->flags & (IFF_LOOPBACK | IFF_NOARP)) {

                /*

                 * FIXME: fill in the last byte of the dest ipaddr here to better

                 * comply with RFC1051 in "noarp" mode.

                 */

                pkt->hard.dest = 0;

                return hdr_size;

        }

        /* otherwise, just fill it in and go! */

        pkt->hard.dest = daddr;

        return hdr_size;        /* success */

}

static int prepare_tx(struct net_device *dev, struct archdr *pkt, int length,

                      int bufnum)

{

        struct arcnet_local *lp = dev->priv;

        struct arc_hardware *hard = &pkt->hard;

        int ofs;

        BUGMSG(D_DURING, "prepare_tx: txbufs=%d/%d/%d\n",

               lp->next_tx, lp->cur_tx, bufnum);

        length -= ARC_HDR_SIZE; /* hard header is not included in packet length */

        if (length > XMTU) {

                /* should never happen! other people already check for this. */

                BUGMSG(D_NORMAL, "Bug!  prepare_tx with size %d (> %d)\n",

                       length, XMTU);

                length = XMTU;

        }

        if (length > MinTU) {

                hard->offset[0] = 0;

                hard->offset[1] = ofs = 512 - length;

        } else if (length > MTU) {

                hard->offset[0] = 0;

                hard->offset[1] = ofs = 512 - length - 3;

        } else

                hard->offset[0] = ofs = 256 - length;

        lp->hw.copy_to_card(dev, bufnum, 0, hard, ARC_HDR_SIZE);

        lp->hw.copy_to_card(dev, bufnum, ofs, &pkt->soft, length);

        lp->lastload_dest = hard->dest;

        return 1;               /* done */

}