text: /*
   * Linux ARCnet driver - "cap mode" packet encapsulation.
   * It adds sequence numbers to packets for communicating between a user space
   * application and the driver. After a transmit it sends a packet with protocol
   * byte 0 back up to the userspace containing the sequence number of the packet
   * plus the transmit-status on the ArcNet.
   *
   * Written 2002-4 by Esben Nielsen, Vestas Wind Systems A/S
   * Derived from arc-rawmode.c by Avery Pennarun.
   * arc-rawmode was in turned based on skeleton.c, see below.
   *
   * **********************
   *
   * 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
   *
   * **********************
   */
  
  #define pr_fmt(fmt) "arcnet:" KBUILD_MODNAME ": " fmt
  
  #include <linux/module.h>
  #include <linux/gfp.h>
  #include <linux/init.h>
  #include <linux/if_arp.h>
  #include <net/arp.h>
  #include <linux/netdevice.h>
  #include <linux/skbuff.h>
  
  #include "arcdevice.h"
  
  /* packet receiver */
  static void rx(struct net_device *dev, int bufnum,
  	       struct archdr *pkthdr, int length)
  {
  	struct arcnet_local *lp = netdev_priv(dev);
  	struct sk_buff *skb;
  	struct archdr *pkt = pkthdr;
  	char *pktbuf, *pkthdrbuf;
  	int ofs;
  
  	arc_printk(D_DURING, dev, "it's a raw(cap) packet (length=%d)\n",
  		   length);
  
  	if (length >= MinTU)
  		ofs = 512 - length;
  	else
  		ofs = 256 - length;
  
  	skb = alloc_skb(length + ARC_HDR_SIZE + sizeof(int), GFP_ATOMIC);
  	if (!skb) {
  		dev->stats.rx_dropped++;
  		return;
  	}
  	skb_put(skb, length + ARC_HDR_SIZE + sizeof(int));
  	skb->dev = dev;
  	skb_reset_mac_header(skb);
  	pkt = (struct archdr *)skb_mac_header(skb);
  	skb_pull(skb, ARC_HDR_SIZE);
  
  	/* up to sizeof(pkt->soft) has already been copied from the card
  	 * squeeze in an int for the cap encapsulation
  	 * use these variables to be sure we count in bytes, not in
  	 * sizeof(struct archdr)
  	 */
  	pktbuf = (char *)pkt;
  	pkthdrbuf = (char *)pkthdr;
  	memcpy(pktbuf, pkthdrbuf, ARC_HDR_SIZE + sizeof(pkt->soft.cap.proto));
  	memcpy(pktbuf + ARC_HDR_SIZE + sizeof(pkt->soft.cap.proto) + sizeof(int),
  	       pkthdrbuf + ARC_HDR_SIZE + sizeof(pkt->soft.cap.proto),
  	       sizeof(struct archdr) - ARC_HDR_SIZE - sizeof(pkt->soft.cap.proto));
  
  	if (length > sizeof(pkt->soft))
  		lp->hw.copy_from_card(dev, bufnum, ofs + sizeof(pkt->soft),
  				      pkt->soft.raw + sizeof(pkt->soft)
  				      + sizeof(int),
  				      length - sizeof(pkt->soft));
  
  	if (BUGLVL(D_SKB))
  		arcnet_dump_skb(dev, skb, "rx");
  
  	skb->protocol = cpu_to_be16(ETH_P_ARCNET);
  	netif_rx(skb);
  }
  
  /* Create the ARCnet hard/soft headers for cap mode.
   * There aren't any soft headers in cap mode - not even the protocol id.
   */
  static int build_header(struct sk_buff *skb,
  			struct net_device *dev,
  			unsigned short type,
  			uint8_t daddr)
  {
  	int hdr_size = ARC_HDR_SIZE;
  	struct archdr *pkt = skb_push(skb, hdr_size);
  
  	arc_printk(D_PROTO, dev, "Preparing header for cap packet %x.\n",
  		   *((int *)&pkt->soft.cap.cookie[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 = netdev_priv(dev);
  	struct arc_hardware *hard = &pkt->hard;
  	int ofs;
  
  	/* hard header is not included in packet length */
  	length -= ARC_HDR_SIZE;
  	/* And neither is the cookie field */
  	length -= sizeof(int);
  
  	arc_printk(D_DURING, dev, "prepare_tx: txbufs=%d/%d/%d\n",
  		   lp->next_tx, lp->cur_tx, bufnum);
  
  	arc_printk(D_PROTO, dev, "Sending for cap packet %x.\n",
  		   *((int *)&pkt->soft.cap.cookie[0]));
  
  	if (length > XMTU) {
  		/* should never happen! other people already check for this. */
  		arc_printk(D_NORMAL, dev, "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;
  	}
  
  	arc_printk(D_DURING, dev, "prepare_tx: length=%d ofs=%d\n",
  		   length, ofs);
  
  	/* Copy the arcnet-header + the protocol byte down: */
  	lp->hw.copy_to_card(dev, bufnum, 0, hard, ARC_HDR_SIZE);
  	lp->hw.copy_to_card(dev, bufnum, ofs, &pkt->soft.cap.proto,
  			    sizeof(pkt->soft.cap.proto));
  
  	/* Skip the extra integer we have written into it as a cookie
  	 * but write the rest of the message:
  	 */
  	lp->hw.copy_to_card(dev, bufnum, ofs + 1,
  			    ((unsigned char *)&pkt->soft.cap.mes), length - 1);
  
  	lp->lastload_dest = hard->dest;
  
  	return 1;	/* done */
  }
  
  static int ack_tx(struct net_device *dev, int acked)
  {
  	struct arcnet_local *lp = netdev_priv(dev);
  	struct sk_buff *ackskb;
  	struct archdr *ackpkt;
  	int length = sizeof(struct arc_cap);
  
  	arc_printk(D_DURING, dev, "capmode: ack_tx: protocol: %x: result: %d\n",
  		   lp->outgoing.skb->protocol, acked);
  
  	if (BUGLVL(D_SKB))
  		arcnet_dump_skb(dev, lp->outgoing.skb, "ack_tx");
  
  	/* Now alloc a skb to send back up through the layers: */
  	ackskb = alloc_skb(length + ARC_HDR_SIZE, GFP_ATOMIC);
  	if (!ackskb)
  		goto free_outskb;
  
  	skb_put(ackskb, length + ARC_HDR_SIZE);
  	ackskb->dev = dev;
  
  	skb_reset_mac_header(ackskb);
  	ackpkt = (struct archdr *)skb_mac_header(ackskb);
  	/* skb_pull(ackskb, ARC_HDR_SIZE); */
  
  	skb_copy_from_linear_data(lp->outgoing.skb, ackpkt,
  				  ARC_HDR_SIZE + sizeof(struct arc_cap));
  	ackpkt->soft.cap.proto = 0; /* using protocol 0 for acknowledge */
  	ackpkt->soft.cap.mes.ack = acked;
  
  	arc_printk(D_PROTO, dev, "Acknowledge for cap packet %x.\n",
  		   *((int *)&ackpkt->soft.cap.cookie[0]));
  
  	ackskb->protocol = cpu_to_be16(ETH_P_ARCNET);
  
  	if (BUGLVL(D_SKB))
  		arcnet_dump_skb(dev, ackskb, "ack_tx_recv");
  	netif_rx(ackskb);
  
  free_outskb:
  	dev_kfree_skb_irq(lp->outgoing.skb);
  	lp->outgoing.proto = NULL;
  			/* We are always finished when in this protocol */
  
  	return 0;
  }
  
  static struct ArcProto capmode_proto = {
  	.suffix		= 'r',
  	.mtu		= XMTU,
  	.rx		= rx,
  	.build_header	= build_header,
  	.prepare_tx	= prepare_tx,
  	.ack_tx		= ack_tx
  };
  
  static int __init capmode_module_init(void)
  {
  	int count;
  
  	pr_info("cap mode (`c') encapsulation support loaded\n");
  
  	for (count = 1; count <= 8; count++)
  		if (arc_proto_map[count] == arc_proto_default)
  			arc_proto_map[count] = &capmode_proto;
  
  	/* for cap mode, we only set the bcast proto if there's no better one */
  	if (arc_bcast_proto == arc_proto_default)
  		arc_bcast_proto = &capmode_proto;
  
  	arc_proto_default = &capmode_proto;
  	arc_raw_proto = &capmode_proto;
  
  	return 0;
  }
  
  static void __exit capmode_module_exit(void)
  {
  	arcnet_unregister_proto(&capmode_proto);
  }
  module_init(capmode_module_init);
  module_exit(capmode_module_exit);
  
  MODULE_LICENSE("GPL");
  