/*
   * IPv4 over IEEE 1394, per RFC 2734
   *
   * Copyright (C) 2009 Jay Fenlason <fenlason@redhat.com>
   *
   * based on eth1394 by Ben Collins et al
   */

  #include <linux/bug.h>

  #include <linux/compiler.h>

  #include <linux/delay.h>

  #include <linux/device.h>

  #include <linux/ethtool.h>

  #include <linux/firewire.h>
  #include <linux/firewire-constants.h>
  #include <linux/highmem.h>
  #include <linux/in.h>
  #include <linux/ip.h>

  #include <linux/jiffies.h>

  #include <linux/mod_devicetable.h>
  #include <linux/module.h>
  #include <linux/moduleparam.h>

  #include <linux/mutex.h>

  #include <linux/netdevice.h>
  #include <linux/skbuff.h>

  #include <linux/slab.h>

  #include <linux/spinlock.h>

  
  #include <asm/unaligned.h>
  #include <net/arp.h>

  /* rx limits */
  #define FWNET_MAX_FRAGMENTS		30 /* arbitrary, > TX queue depth */
  #define FWNET_ISO_PAGE_COUNT		(PAGE_SIZE < 16*1024 ? 4 : 2)
  
  /* tx limits */
  #define FWNET_MAX_QUEUED_DATAGRAMS	20 /* < 64 = number of tlabels */
  #define FWNET_MIN_QUEUED_DATAGRAMS	10 /* should keep AT DMA busy enough */
  #define FWNET_TX_QUEUE_LEN		FWNET_MAX_QUEUED_DATAGRAMS /* ? */

  #define IEEE1394_BROADCAST_CHANNEL	31
  #define IEEE1394_ALL_NODES		(0xffc0 | 0x003f)
  #define IEEE1394_MAX_PAYLOAD_S100	512
  #define FWNET_NO_FIFO_ADDR		(~0ULL)

  #define IANA_SPECIFIER_ID		0x00005eU
  #define RFC2734_SW_VERSION		0x000001U

  #define IEEE1394_GASP_HDR_SIZE	8

  #define RFC2374_UNFRAG_HDR_SIZE	4
  #define RFC2374_FRAG_HDR_SIZE	8
  #define RFC2374_FRAG_OVERHEAD	4

  #define RFC2374_HDR_UNFRAG	0	/* unfragmented		*/
  #define RFC2374_HDR_FIRSTFRAG	1	/* first fragment	*/
  #define RFC2374_HDR_LASTFRAG	2	/* last fragment	*/
  #define RFC2374_HDR_INTFRAG	3	/* interior fragment	*/

  #define RFC2734_HW_ADDR_LEN	16

  struct rfc2734_arp {
  	__be16 hw_type;		/* 0x0018	*/
  	__be16 proto_type;	/* 0x0806       */
  	u8 hw_addr_len;		/* 16		*/
  	u8 ip_addr_len;		/* 4		*/
  	__be16 opcode;		/* ARP Opcode	*/
  	/* Above is exactly the same format as struct arphdr */

  	__be64 s_uniq_id;	/* Sender's 64bit EUI			*/
  	u8 max_rec;		/* Sender's max packet size		*/
  	u8 sspd;		/* Sender's max speed			*/
  	__be16 fifo_hi;		/* hi 16bits of sender's FIFO addr	*/
  	__be32 fifo_lo;		/* lo 32bits of sender's FIFO addr	*/
  	__be32 sip;		/* Sender's IP Address			*/
  	__be32 tip;		/* IP Address of requested hw addr	*/

  } __packed;

  /* This header format is specific to this driver implementation. */
  #define FWNET_ALEN	8
  #define FWNET_HLEN	10
  struct fwnet_header {
  	u8 h_dest[FWNET_ALEN];	/* destination address */
  	__be16 h_proto;		/* packet type ID field */

  } __packed;

  /* IPv4 and IPv6 encapsulation header */
  struct rfc2734_header {

  	u32 w0;
  	u32 w1;
  };

  #define fwnet_get_hdr_lf(h)		(((h)->w0 & 0xc0000000) >> 30)
  #define fwnet_get_hdr_ether_type(h)	(((h)->w0 & 0x0000ffff))
  #define fwnet_get_hdr_dg_size(h)	(((h)->w0 & 0x0fff0000) >> 16)
  #define fwnet_get_hdr_fg_off(h)		(((h)->w0 & 0x00000fff))
  #define fwnet_get_hdr_dgl(h)		(((h)->w1 & 0xffff0000) >> 16)

  #define fwnet_set_hdr_lf(lf)		((lf)  << 30)
  #define fwnet_set_hdr_ether_type(et)	(et)
  #define fwnet_set_hdr_dg_size(dgs)	((dgs) << 16)
  #define fwnet_set_hdr_fg_off(fgo)	(fgo)

  #define fwnet_set_hdr_dgl(dgl)		((dgl) << 16)

  static inline void fwnet_make_uf_hdr(struct rfc2734_header *hdr,
  		unsigned ether_type)
  {
  	hdr->w0 = fwnet_set_hdr_lf(RFC2374_HDR_UNFRAG)
  		  | fwnet_set_hdr_ether_type(ether_type);
  }

  static inline void fwnet_make_ff_hdr(struct rfc2734_header *hdr,
  		unsigned ether_type, unsigned dg_size, unsigned dgl)
  {
  	hdr->w0 = fwnet_set_hdr_lf(RFC2374_HDR_FIRSTFRAG)
  		  | fwnet_set_hdr_dg_size(dg_size)
  		  | fwnet_set_hdr_ether_type(ether_type);
  	hdr->w1 = fwnet_set_hdr_dgl(dgl);
  }

  static inline void fwnet_make_sf_hdr(struct rfc2734_header *hdr,
  		unsigned lf, unsigned dg_size, unsigned fg_off, unsigned dgl)
  {
  	hdr->w0 = fwnet_set_hdr_lf(lf)
  		  | fwnet_set_hdr_dg_size(dg_size)
  		  | fwnet_set_hdr_fg_off(fg_off);
  	hdr->w1 = fwnet_set_hdr_dgl(dgl);
  }

  
  /* This list keeps track of what parts of the datagram have been filled in */

  struct fwnet_fragment_info {
  	struct list_head fi_link;

  	u16 offset;
  	u16 len;
  };

  struct fwnet_partial_datagram {
  	struct list_head pd_link;
  	struct list_head fi_list;

  	struct sk_buff *skb;
  	/* FIXME Why not use skb->data? */
  	char *pbuf;
  	u16 datagram_label;
  	u16 ether_type;
  	u16 datagram_size;
  };

  static DEFINE_MUTEX(fwnet_device_mutex);
  static LIST_HEAD(fwnet_device_list);

  struct fwnet_device {

  	struct list_head dev_link;

  	spinlock_t lock;

  	enum {
  		FWNET_BROADCAST_ERROR,
  		FWNET_BROADCAST_RUNNING,
  		FWNET_BROADCAST_STOPPED,
  	} broadcast_state;

  	struct fw_iso_context *broadcast_rcv_context;
  	struct fw_iso_buffer broadcast_rcv_buffer;
  	void **broadcast_rcv_buffer_ptrs;
  	unsigned broadcast_rcv_next_ptr;
  	unsigned num_broadcast_rcv_ptrs;
  	unsigned rcv_buffer_size;
  	/*
  	 * This value is the maximum unfragmented datagram size that can be
  	 * sent by the hardware.  It already has the GASP overhead and the
  	 * unfragmented datagram header overhead calculated into it.
  	 */
  	unsigned broadcast_xmt_max_payload;
  	u16 broadcast_xmt_datagramlabel;
  
  	/*

  	 * The CSR address that remote nodes must send datagrams to for us to

  	 * receive them.
  	 */
  	struct fw_address_handler handler;
  	u64 local_fifo;

  	/* Number of tx datagrams that have been queued but not yet acked */
  	int queued_datagrams;

  	int peer_count;

  	struct list_head peer_list;

  	struct fw_card *card;

  	struct net_device *netdev;
  };
  
  struct fwnet_peer {
  	struct list_head peer_link;
  	struct fwnet_device *dev;
  	u64 guid;
  	u64 fifo;

  	__be32 ip;

  
  	/* guarded by dev->lock */
  	struct list_head pd_list; /* received partial datagrams */
  	unsigned pdg_size;        /* pd_list size */
  
  	u16 datagram_label;       /* outgoing datagram label */

  	u16 max_payload;          /* includes RFC2374_FRAG_HDR_SIZE overhead */

  	int node_id;
  	int generation;
  	unsigned speed;

  };
  
  /* This is our task struct. It's used for the packet complete callback.  */

  struct fwnet_packet_task {

  	struct fw_transaction transaction;

  	struct rfc2734_header hdr;

  	struct sk_buff *skb;

  	struct fwnet_device *dev;

  	int outstanding_pkts;

  	u64 fifo_addr;
  	u16 dest_node;

  	u16 max_payload;

  	u8 generation;
  	u8 speed;

  	u8 enqueued;

  };

  /*
   * saddr == NULL means use device source address.
   * daddr == NULL means leave destination address (eg unresolved arp).
   */
  static int fwnet_header_create(struct sk_buff *skb, struct net_device *net,
  			unsigned short type, const void *daddr,
  			const void *saddr, unsigned len)
  {
  	struct fwnet_header *h;

  	h = (struct fwnet_header *)skb_push(skb, sizeof(*h));
  	put_unaligned_be16(type, &h->h_proto);

  	if (net->flags & (IFF_LOOPBACK | IFF_NOARP)) {
  		memset(h->h_dest, 0, net->addr_len);

  		return net->hard_header_len;

  	}
  
  	if (daddr) {

  		memcpy(h->h_dest, daddr, net->addr_len);
  
  		return net->hard_header_len;

  	}

  	return -net->hard_header_len;

  }

  static int fwnet_header_rebuild(struct sk_buff *skb)

  {

  	struct fwnet_header *h = (struct fwnet_header *)skb->data;

  	if (get_unaligned_be16(&h->h_proto) == ETH_P_IP)
  		return arp_find((unsigned char *)&h->h_dest, skb);

  	fw_notify("%s: unable to resolve type %04x addresses
  ",
  		  skb->dev->name, be16_to_cpu(h->h_proto));

  	return 0;
  }

  static int fwnet_header_cache(const struct neighbour *neigh,

  			      struct hh_cache *hh, __be16 type)

  {
  	struct net_device *net;
  	struct fwnet_header *h;

  	if (type == cpu_to_be16(ETH_P_802_3))

  		return -1;

  	net = neigh->dev;
  	h = (struct fwnet_header *)((u8 *)hh->hh_data + 16 - sizeof(*h));

  	h->h_proto = type;

  	memcpy(h->h_dest, neigh->ha, net->addr_len);
  	hh->hh_len = FWNET_HLEN;

  	return 0;
  }
  
  /* Called by Address Resolution module to notify changes in address. */

  static void fwnet_header_cache_update(struct hh_cache *hh,
  		const struct net_device *net, const unsigned char *haddr)
  {
  	memcpy((u8 *)hh->hh_data + 16 - FWNET_HLEN, haddr, net->addr_len);

  }

  static int fwnet_header_parse(const struct sk_buff *skb, unsigned char *haddr)
  {
  	memcpy(haddr, skb->dev->dev_addr, FWNET_ALEN);
  
  	return FWNET_ALEN;

  }

  static const struct header_ops fwnet_header_ops = {
  	.create         = fwnet_header_create,
  	.rebuild        = fwnet_header_rebuild,
  	.cache		= fwnet_header_cache,
  	.cache_update	= fwnet_header_cache_update,
  	.parse          = fwnet_header_parse,

  };

  /* FIXME: is this correct for all cases? */

  static bool fwnet_frag_overlap(struct fwnet_partial_datagram *pd,
  			       unsigned offset, unsigned len)

  {

  	struct fwnet_fragment_info *fi;

  	unsigned end = offset + len;

  	list_for_each_entry(fi, &pd->fi_list, fi_link)
  		if (offset < fi->offset + fi->len && end > fi->offset)

  			return true;

  	return false;
  }
  
  /* Assumes that new fragment does not overlap any existing fragments */

  static struct fwnet_fragment_info *fwnet_frag_new(
  	struct fwnet_partial_datagram *pd, unsigned offset, unsigned len)
  {
  	struct fwnet_fragment_info *fi, *fi2, *new;

  	struct list_head *list;

  	list = &pd->fi_list;
  	list_for_each_entry(fi, &pd->fi_list, fi_link) {

  		if (fi->offset + fi->len == offset) {
  			/* The new fragment can be tacked on to the end */
  			/* Did the new fragment plug a hole? */

  			fi2 = list_entry(fi->fi_link.next,
  					 struct fwnet_fragment_info, fi_link);

  			if (fi->offset + fi->len == fi2->offset) {

  				/* glue fragments together */
  				fi->len += len + fi2->len;

  				list_del(&fi2->fi_link);

  				kfree(fi2);
  			} else {

  				fi->len += len;
  			}

  			return fi;
  		}
  		if (offset + len == fi->offset) {
  			/* The new fragment can be tacked on to the beginning */
  			/* Did the new fragment plug a hole? */

  			fi2 = list_entry(fi->fi_link.prev,
  					 struct fwnet_fragment_info, fi_link);

  			if (fi2->offset + fi2->len == fi->offset) {
  				/* glue fragments together */

  				fi2->len += fi->len + len;

  				list_del(&fi->fi_link);

  				kfree(fi);

  				return fi2;
  			}

  			fi->offset = offset;
  			fi->len += len;

  			return fi;
  		}
  		if (offset > fi->offset + fi->len) {

  			list = &fi->fi_link;

  			break;
  		}
  		if (offset + len < fi->offset) {

  			list = fi->fi_link.prev;

  			break;
  		}
  	}
  
  	new = kmalloc(sizeof(*new), GFP_ATOMIC);
  	if (!new) {

  		fw_error("out of memory
  ");

  		return NULL;
  	}
  
  	new->offset = offset;
  	new->len = len;

  	list_add(&new->fi_link, list);

  	return new;
  }

  static struct fwnet_partial_datagram *fwnet_pd_new(struct net_device *net,
  		struct fwnet_peer *peer, u16 datagram_label, unsigned dg_size,
  		void *frag_buf, unsigned frag_off, unsigned frag_len)
  {
  	struct fwnet_partial_datagram *new;
  	struct fwnet_fragment_info *fi;

  
  	new = kmalloc(sizeof(*new), GFP_ATOMIC);
  	if (!new)
  		goto fail;

  
  	INIT_LIST_HEAD(&new->fi_list);
  	fi = fwnet_frag_new(new, frag_off, frag_len);
  	if (fi == NULL)

  		goto fail_w_new;

  	new->datagram_label = datagram_label;
  	new->datagram_size = dg_size;

  	new->skb = dev_alloc_skb(dg_size + net->hard_header_len + 15);
  	if (new->skb == NULL)

  		goto fail_w_fi;

  
  	skb_reserve(new->skb, (net->hard_header_len + 15) & ~15);

  	new->pbuf = skb_put(new->skb, dg_size);
  	memcpy(new->pbuf + frag_off, frag_buf, frag_len);

  	list_add_tail(&new->pd_link, &peer->pd_list);

  	return new;
  
  fail_w_fi:
  	kfree(fi);
  fail_w_new:
  	kfree(new);
  fail:

  	fw_error("out of memory
  ");

  	return NULL;
  }

  static struct fwnet_partial_datagram *fwnet_pd_find(struct fwnet_peer *peer,
  						    u16 datagram_label)
  {
  	struct fwnet_partial_datagram *pd;

  	list_for_each_entry(pd, &peer->pd_list, pd_link)
  		if (pd->datagram_label == datagram_label)

  			return pd;

  	return NULL;
  }

  static void fwnet_pd_delete(struct fwnet_partial_datagram *old)
  {
  	struct fwnet_fragment_info *fi, *n;

  	list_for_each_entry_safe(fi, n, &old->fi_list, fi_link)

  		kfree(fi);

  
  	list_del(&old->pd_link);

  	dev_kfree_skb_any(old->skb);
  	kfree(old);
  }

  static bool fwnet_pd_update(struct fwnet_peer *peer,
  		struct fwnet_partial_datagram *pd, void *frag_buf,
  		unsigned frag_off, unsigned frag_len)
  {
  	if (fwnet_frag_new(pd, frag_off, frag_len) == NULL)

  		return false;

  	memcpy(pd->pbuf + frag_off, frag_buf, frag_len);
  
  	/*

  	 * Move list entry to beginning of list so that oldest partial

  	 * datagrams percolate to the end of the list
  	 */

  	list_move_tail(&pd->pd_link, &peer->pd_list);

  	return true;
  }

  static bool fwnet_pd_is_complete(struct fwnet_partial_datagram *pd)
  {
  	struct fwnet_fragment_info *fi;

  	fi = list_entry(pd->fi_list.next, struct fwnet_fragment_info, fi_link);

  	return fi->len == pd->datagram_size;

  }

  /* caller must hold dev->lock */

  static struct fwnet_peer *fwnet_peer_find_by_guid(struct fwnet_device *dev,
  						  u64 guid)
  {

  	struct fwnet_peer *peer;

  	list_for_each_entry(peer, &dev->peer_list, peer_link)
  		if (peer->guid == guid)
  			return peer;

  	return NULL;

  }

  /* caller must hold dev->lock */

  static struct fwnet_peer *fwnet_peer_find_by_node_id(struct fwnet_device *dev,

  						int node_id, int generation)

  {

  	struct fwnet_peer *peer;

  	list_for_each_entry(peer, &dev->peer_list, peer_link)
  		if (peer->node_id    == node_id &&
  		    peer->generation == generation)
  			return peer;

  	return NULL;

  }

  /* See IEEE 1394-2008 table 6-4, table 8-8, table 16-18. */
  static unsigned fwnet_max_payload(unsigned max_rec, unsigned speed)

  {

  	max_rec = min(max_rec, speed + 8);

  	max_rec = clamp(max_rec, 8U, 11U); /* 512...4096 */

  
  	return (1 << (max_rec + 1)) - RFC2374_FRAG_HDR_SIZE;

  }

  static int fwnet_finish_incoming_packet(struct net_device *net,
  					struct sk_buff *skb, u16 source_node_id,
  					bool is_broadcast, u16 ether_type)
  {
  	struct fwnet_device *dev;
  	static const __be64 broadcast_hw = cpu_to_be64(~0ULL);

  	int status;

  	__be64 guid;

  	dev = netdev_priv(net);

  	/* Write metadata, and then pass to the receive level */

  	skb->dev = net;

  	skb->ip_summed = CHECKSUM_UNNECESSARY;  /* don't check it */
  
  	/*
  	 * Parse the encapsulation header. This actually does the job of
  	 * converting to an ethernet frame header, as well as arp
  	 * conversion if needed. ARP conversion is easier in this
  	 * direction, since we are using ethernet as our backend.
  	 */
  	/*
  	 * If this is an ARP packet, convert it. First, we want to make
  	 * use of some of the fields, since they tell us a little bit
  	 * about the sending machine.
  	 */
  	if (ether_type == ETH_P_ARP) {

  		struct rfc2734_arp *arp1394;

  		struct arphdr *arp;
  		unsigned char *arp_ptr;
  		u64 fifo_addr;

  		u64 peer_guid;

  		unsigned sspd;

  		u16 max_payload;

  		struct fwnet_peer *peer;

  		unsigned long flags;
  
  		arp1394   = (struct rfc2734_arp *)skb->data;
  		arp       = (struct arphdr *)skb->data;
  		arp_ptr   = (unsigned char *)(arp + 1);
  		peer_guid = get_unaligned_be64(&arp1394->s_uniq_id);
  		fifo_addr = (u64)get_unaligned_be16(&arp1394->fifo_hi) << 32
  				| get_unaligned_be32(&arp1394->fifo_lo);

  		sspd = arp1394->sspd;

  		/* Sanity check.  OS X 10.3 PPC reportedly sends 131. */
  		if (sspd > SCODE_3200) {
  			fw_notify("sspd %x out of range
  ", sspd);

  			sspd = SCODE_3200;

  		}

  		max_payload = fwnet_max_payload(arp1394->max_rec, sspd);

  		spin_lock_irqsave(&dev->lock, flags);

  		peer = fwnet_peer_find_by_guid(dev, peer_guid);

  		if (peer) {
  			peer->fifo = fifo_addr;
  
  			if (peer->speed > sspd)
  				peer->speed = sspd;
  			if (peer->max_payload > max_payload)
  				peer->max_payload = max_payload;

  
  			peer->ip = arp1394->sip;

  		}
  		spin_unlock_irqrestore(&dev->lock, flags);

  		if (!peer) {
  			fw_notify("No peer for ARP packet from %016llx
  ",
  				  (unsigned long long)peer_guid);

  			goto no_peer;

  		}

  		/*
  		 * Now that we're done with the 1394 specific stuff, we'll
  		 * need to alter some of the data.  Believe it or not, all
  		 * that needs to be done is sender_IP_address needs to be
  		 * moved, the destination hardware address get stuffed
  		 * in and the hardware address length set to 8.
  		 *
  		 * IMPORTANT: The code below overwrites 1394 specific data
  		 * needed above so keep the munging of the data for the
  		 * higher level IP stack last.
  		 */
  
  		arp->ar_hln = 8;

  		/* skip over sender unique id */
  		arp_ptr += arp->ar_hln;
  		/* move sender IP addr */
  		put_unaligned(arp1394->sip, (u32 *)arp_ptr);
  		/* skip over sender IP addr */
  		arp_ptr += arp->ar_pln;

  
  		if (arp->ar_op == htons(ARPOP_REQUEST))
  			memset(arp_ptr, 0, sizeof(u64));
  		else

  			memcpy(arp_ptr, net->dev_addr, sizeof(u64));

  	}
  
  	/* Now add the ethernet header. */

  	guid = cpu_to_be64(dev->card->guid);
  	if (dev_hard_header(skb, net, ether_type,
  			   is_broadcast ? &broadcast_hw : &guid,
  			   NULL, skb->len) >= 0) {
  		struct fwnet_header *eth;

  		u16 *rawp;
  		__be16 protocol;
  
  		skb_reset_mac_header(skb);
  		skb_pull(skb, sizeof(*eth));

  		eth = (struct fwnet_header *)skb_mac_header(skb);

  		if (*eth->h_dest & 1) {

  			if (memcmp(eth->h_dest, net->broadcast,
  				   net->addr_len) == 0)

  				skb->pkt_type = PACKET_BROADCAST;

  #if 0
  			else
  				skb->pkt_type = PACKET_MULTICAST;
  #endif
  		} else {

  			if (memcmp(eth->h_dest, net->dev_addr, net->addr_len))

  				skb->pkt_type = PACKET_OTHERHOST;

  		}
  		if (ntohs(eth->h_proto) >= 1536) {

  			protocol = eth->h_proto;
  		} else {
  			rawp = (u16 *)skb->data;

  			if (*rawp == 0xffff)

  				protocol = htons(ETH_P_802_3);

  			else

  				protocol = htons(ETH_P_802_2);

  		}
  		skb->protocol = protocol;
  	}
  	status = netif_rx(skb);

  	if (status == NET_RX_DROP) {
  		net->stats.rx_errors++;
  		net->stats.rx_dropped++;

  	} else {

  		net->stats.rx_packets++;
  		net->stats.rx_bytes += skb->len;

  	}

  	return 0;

   no_peer:

  	net->stats.rx_errors++;
  	net->stats.rx_dropped++;

  	dev_kfree_skb_any(skb);

  	return -ENOENT;

  }

  static int fwnet_incoming_packet(struct fwnet_device *dev, __be32 *buf, int len,

  				 int source_node_id, int generation,
  				 bool is_broadcast)

  {

  	struct sk_buff *skb;

  	struct net_device *net = dev->netdev;

  	struct rfc2734_header hdr;

  	unsigned lf;
  	unsigned long flags;

  	struct fwnet_peer *peer;
  	struct fwnet_partial_datagram *pd;

  	int fg_off;
  	int dg_size;
  	u16 datagram_label;
  	int retval;
  	u16 ether_type;

  	hdr.w0 = be32_to_cpu(buf[0]);
  	lf = fwnet_get_hdr_lf(&hdr);
  	if (lf == RFC2374_HDR_UNFRAG) {

  		/*
  		 * An unfragmented datagram has been received by the ieee1394
  		 * bus. Build an skbuff around it so we can pass it to the
  		 * high level network layer.
  		 */

  		ether_type = fwnet_get_hdr_ether_type(&hdr);

  		buf++;

  		len -= RFC2374_UNFRAG_HDR_SIZE;

  		skb = dev_alloc_skb(len + net->hard_header_len + 15);

  		if (unlikely(!skb)) {

  			fw_error("out of memory
  ");
  			net->stats.rx_dropped++;

  			return -ENOMEM;

  		}

  		skb_reserve(skb, (net->hard_header_len + 15) & ~15);
  		memcpy(skb_put(skb, len), buf, len);
  
  		return fwnet_finish_incoming_packet(net, skb, source_node_id,
  						    is_broadcast, ether_type);

  	}
  	/* A datagram fragment has been received, now the fun begins. */
  	hdr.w1 = ntohl(buf[1]);

  	buf += 2;
  	len -= RFC2374_FRAG_HDR_SIZE;
  	if (lf == RFC2374_HDR_FIRSTFRAG) {
  		ether_type = fwnet_get_hdr_ether_type(&hdr);

  		fg_off = 0;
  	} else {

  		ether_type = 0;
  		fg_off = fwnet_get_hdr_fg_off(&hdr);

  	}

  	datagram_label = fwnet_get_hdr_dgl(&hdr);
  	dg_size = fwnet_get_hdr_dg_size(&hdr); /* ??? + 1 */

  	spin_lock_irqsave(&dev->lock, flags);
  
  	peer = fwnet_peer_find_by_node_id(dev, source_node_id, generation);

  	if (!peer) {
  		retval = -ENOENT;
  		goto fail;
  	}

  
  	pd = fwnet_pd_find(peer, datagram_label);

  	if (pd == NULL) {

  		while (peer->pdg_size >= FWNET_MAX_FRAGMENTS) {

  			/* remove the oldest */

  			fwnet_pd_delete(list_first_entry(&peer->pd_list,
  				struct fwnet_partial_datagram, pd_link));
  			peer->pdg_size--;

  		}

  		pd = fwnet_pd_new(net, peer, datagram_label,
  				  dg_size, buf, fg_off, len);
  		if (pd == NULL) {

  			retval = -ENOMEM;

  			goto fail;

  		}

  		peer->pdg_size++;

  	} else {

  		if (fwnet_frag_overlap(pd, fg_off, len) ||
  		    pd->datagram_size != dg_size) {

  			/*
  			 * Differing datagram sizes or overlapping fragments,

  			 * discard old datagram and start a new one.

  			 */

  			fwnet_pd_delete(pd);
  			pd = fwnet_pd_new(net, peer, datagram_label,
  					  dg_size, buf, fg_off, len);
  			if (pd == NULL) {

  				peer->pdg_size--;

  				retval = -ENOMEM;
  				goto fail;

  			}
  		} else {

  			if (!fwnet_pd_update(peer, pd, buf, fg_off, len)) {

  				/*
  				 * Couldn't save off fragment anyway
  				 * so might as well obliterate the
  				 * datagram now.
  				 */

  				fwnet_pd_delete(pd);
  				peer->pdg_size--;

  				retval = -ENOMEM;
  				goto fail;

  			}
  		}
  	} /* new datagram or add to existing one */

  	if (lf == RFC2374_HDR_FIRSTFRAG)

  		pd->ether_type = ether_type;

  
  	if (fwnet_pd_is_complete(pd)) {

  		ether_type = pd->ether_type;

  		peer->pdg_size--;

  		skb = skb_get(pd->skb);

  		fwnet_pd_delete(pd);

  		spin_unlock_irqrestore(&dev->lock, flags);

  
  		return fwnet_finish_incoming_packet(net, skb, source_node_id,
  						    false, ether_type);

  	}
  	/*
  	 * Datagram is not complete, we're done for the
  	 * moment.
  	 */

  	retval = 0;

   fail:

  	spin_unlock_irqrestore(&dev->lock, flags);

  	return retval;

  }

  static void fwnet_receive_packet(struct fw_card *card, struct fw_request *r,
  		int tcode, int destination, int source, int generation,

  		unsigned long long offset, void *payload, size_t length,
  		void *callback_data)

  {

  	struct fwnet_device *dev = callback_data;
  	int rcode;

  	if (destination == IEEE1394_ALL_NODES) {
  		kfree(r);

  		return;
  	}

  	if (offset != dev->handler.offset)
  		rcode = RCODE_ADDRESS_ERROR;
  	else if (tcode != TCODE_WRITE_BLOCK_REQUEST)
  		rcode = RCODE_TYPE_ERROR;
  	else if (fwnet_incoming_packet(dev, payload, length,
  				       source, generation, false) != 0) {

  		fw_error("Incoming packet failure
  ");

  		rcode = RCODE_CONFLICT_ERROR;
  	} else
  		rcode = RCODE_COMPLETE;

  	fw_send_response(card, r, rcode);

  }

  static void fwnet_receive_broadcast(struct fw_iso_context *context,
  		u32 cycle, size_t header_length, void *header, void *data)
  {
  	struct fwnet_device *dev;

  	struct fw_iso_packet packet;
  	struct fw_card *card;

  	__be16 *hdr_ptr;
  	__be32 *buf_ptr;

  	int retval;
  	u32 length;
  	u16 source_node_id;
  	u32 specifier_id;
  	u32 ver;
  	unsigned long offset;
  	unsigned long flags;

  	dev = data;
  	card = dev->card;

  	hdr_ptr = header;

  	length = be16_to_cpup(hdr_ptr);
  
  	spin_lock_irqsave(&dev->lock, flags);
  
  	offset = dev->rcv_buffer_size * dev->broadcast_rcv_next_ptr;
  	buf_ptr = dev->broadcast_rcv_buffer_ptrs[dev->broadcast_rcv_next_ptr++];
  	if (dev->broadcast_rcv_next_ptr == dev->num_broadcast_rcv_ptrs)
  		dev->broadcast_rcv_next_ptr = 0;
  
  	spin_unlock_irqrestore(&dev->lock, flags);

  
  	specifier_id =    (be32_to_cpu(buf_ptr[0]) & 0xffff) << 8
  			| (be32_to_cpu(buf_ptr[1]) & 0xff000000) >> 24;

  	ver = be32_to_cpu(buf_ptr[1]) & 0xffffff;

  	source_node_id = be32_to_cpu(buf_ptr[0]) >> 16;

  
  	if (specifier_id == IANA_SPECIFIER_ID && ver == RFC2734_SW_VERSION) {

  		buf_ptr += 2;

  		length -= IEEE1394_GASP_HDR_SIZE;
  		fwnet_incoming_packet(dev, buf_ptr, length,

  				      source_node_id, -1, true);

  	}
  
  	packet.payload_length = dev->rcv_buffer_size;

  	packet.interrupt = 1;
  	packet.skip = 0;
  	packet.tag = 3;
  	packet.sy = 0;

  	packet.header_length = IEEE1394_GASP_HDR_SIZE;
  
  	spin_lock_irqsave(&dev->lock, flags);

  	retval = fw_iso_context_queue(dev->broadcast_rcv_context, &packet,
  				      &dev->broadcast_rcv_buffer, offset);
  
  	spin_unlock_irqrestore(&dev->lock, flags);

  	if (retval >= 0)
  		fw_iso_context_queue_flush(dev->broadcast_rcv_context);
  	else

  		fw_error("requeue failed
  ");

  }

  static struct kmem_cache *fwnet_packet_task_cache;

  static void fwnet_free_ptask(struct fwnet_packet_task *ptask)
  {
  	dev_kfree_skb_any(ptask->skb);
  	kmem_cache_free(fwnet_packet_task_cache, ptask);
  }

  /* Caller must hold dev->lock. */
  static void dec_queued_datagrams(struct fwnet_device *dev)
  {
  	if (--dev->queued_datagrams == FWNET_MIN_QUEUED_DATAGRAMS)
  		netif_wake_queue(dev->netdev);
  }

  static int fwnet_send_packet(struct fwnet_packet_task *ptask);
  
  static void fwnet_transmit_packet_done(struct fwnet_packet_task *ptask)
  {

  	struct fwnet_device *dev = ptask->dev;

  	struct sk_buff *skb = ptask->skb;

  	unsigned long flags;

  	bool free;

  
  	spin_lock_irqsave(&dev->lock, flags);

  	ptask->outstanding_pkts--;
  
  	/* Check whether we or the networking TX soft-IRQ is last user. */

  	free = (ptask->outstanding_pkts == 0 && ptask->enqueued);

  	if (free)

  		dec_queued_datagrams(dev);

  	if (ptask->outstanding_pkts == 0) {

  		dev->netdev->stats.tx_packets++;
  		dev->netdev->stats.tx_bytes += skb->len;
  	}

  
  	spin_unlock_irqrestore(&dev->lock, flags);

  
  	if (ptask->outstanding_pkts > 0) {

  		u16 dg_size;
  		u16 fg_off;
  		u16 datagram_label;
  		u16 lf;

  
  		/* Update the ptask to point to the next fragment and send it */

  		lf = fwnet_get_hdr_lf(&ptask->hdr);

  		switch (lf) {

  		case RFC2374_HDR_LASTFRAG:
  		case RFC2374_HDR_UNFRAG:

  		default:

  			fw_error("Outstanding packet %x lf %x, header %x,%x
  ",
  				 ptask->outstanding_pkts, lf, ptask->hdr.w0,
  				 ptask->hdr.w1);

  			BUG();

  		case RFC2374_HDR_FIRSTFRAG:

  			/* Set frag type here for future interior fragments */

  			dg_size = fwnet_get_hdr_dg_size(&ptask->hdr);
  			fg_off = ptask->max_payload - RFC2374_FRAG_HDR_SIZE;
  			datagram_label = fwnet_get_hdr_dgl(&ptask->hdr);

  			break;

  		case RFC2374_HDR_INTFRAG:
  			dg_size = fwnet_get_hdr_dg_size(&ptask->hdr);
  			fg_off = fwnet_get_hdr_fg_off(&ptask->hdr)
  				  + ptask->max_payload - RFC2374_FRAG_HDR_SIZE;
  			datagram_label = fwnet_get_hdr_dgl(&ptask->hdr);

  			break;
  		}

  		skb_pull(skb, ptask->max_payload);
  		if (ptask->outstanding_pkts > 1) {
  			fwnet_make_sf_hdr(&ptask->hdr, RFC2374_HDR_INTFRAG,
  					  dg_size, fg_off, datagram_label);

  		} else {

  			fwnet_make_sf_hdr(&ptask->hdr, RFC2374_HDR_LASTFRAG,
  					  dg_size, fg_off, datagram_label);
  			ptask->max_payload = skb->len + RFC2374_FRAG_HDR_SIZE;

  		}

  		fwnet_send_packet(ptask);

  	}

  
  	if (free)
  		fwnet_free_ptask(ptask);

  }

  static void fwnet_transmit_packet_failed(struct fwnet_packet_task *ptask)
  {
  	struct fwnet_device *dev = ptask->dev;
  	unsigned long flags;
  	bool free;
  
  	spin_lock_irqsave(&dev->lock, flags);
  
  	/* One fragment failed; don't try to send remaining fragments. */
  	ptask->outstanding_pkts = 0;
  
  	/* Check whether we or the networking TX soft-IRQ is last user. */

  	free = ptask->enqueued;

  	if (free)

  		dec_queued_datagrams(dev);

  
  	dev->netdev->stats.tx_dropped++;
  	dev->netdev->stats.tx_errors++;
  
  	spin_unlock_irqrestore(&dev->lock, flags);
  
  	if (free)
  		fwnet_free_ptask(ptask);
  }

  static void fwnet_write_complete(struct fw_card *card, int rcode,
  				 void *payload, size_t length, void *data)
  {

  	struct fwnet_packet_task *ptask = data;
  	static unsigned long j;
  	static int last_rcode, errors_skipped;

  	if (rcode == RCODE_COMPLETE) {

  		fwnet_transmit_packet_done(ptask);

  	} else {

  		fwnet_transmit_packet_failed(ptask);

  
  		if (printk_timed_ratelimit(&j,  1000) || rcode != last_rcode) {
  			fw_error("fwnet_write_complete: "
  				"failed: %x (skipped %d)
  ", rcode, errors_skipped);
  
  			errors_skipped = 0;
  			last_rcode = rcode;
  		} else
  			errors_skipped++;

  	}

  }

  static int fwnet_send_packet(struct fwnet_packet_task *ptask)
  {
  	struct fwnet_device *dev;

  	unsigned tx_len;

  	struct rfc2734_header *bufhdr;

  	unsigned long flags;

  	bool free;

  	dev = ptask->dev;

  	tx_len = ptask->max_payload;

  	switch (fwnet_get_hdr_lf(&ptask->hdr)) {
  	case RFC2374_HDR_UNFRAG:
  		bufhdr = (struct rfc2734_header *)
  				skb_push(ptask->skb, RFC2374_UNFRAG_HDR_SIZE);
  		put_unaligned_be32(ptask->hdr.w0, &bufhdr->w0);

  		break;

  	case RFC2374_HDR_FIRSTFRAG:
  	case RFC2374_HDR_INTFRAG:
  	case RFC2374_HDR_LASTFRAG:
  		bufhdr = (struct rfc2734_header *)
  				skb_push(ptask->skb, RFC2374_FRAG_HDR_SIZE);
  		put_unaligned_be32(ptask->hdr.w0, &bufhdr->w0);
  		put_unaligned_be32(ptask->hdr.w1, &bufhdr->w1);

  		break;
  
  	default:
  		BUG();
  	}

  	if (ptask->dest_node == IEEE1394_ALL_NODES) {
  		u8 *p;

  		int generation;

  		int node_id;

  
  		/* ptask->generation may not have been set yet */

  		generation = dev->card->generation;

  		smp_rmb();

  		node_id = dev->card->node_id;
  
  		p = skb_push(ptask->skb, 8);
  		put_unaligned_be32(node_id << 16 | IANA_SPECIFIER_ID >> 8, p);
  		put_unaligned_be32((IANA_SPECIFIER_ID & 0xff) << 24
  						| RFC2734_SW_VERSION, &p[4]);
  
  		/* We should not transmit if broadcast_channel.valid == 0. */
  		fw_send_request(dev->card, &ptask->transaction,
  				TCODE_STREAM_DATA,
  				fw_stream_packet_destination_id(3,
  						IEEE1394_BROADCAST_CHANNEL, 0),
  				generation, SCODE_100, 0ULL, ptask->skb->data,
  				tx_len + 8, fwnet_write_complete, ptask);

  		spin_lock_irqsave(&dev->lock, flags);

  
  		/* If the AT tasklet already ran, we may be last user. */

  		free = (ptask->outstanding_pkts == 0 && !ptask->enqueued);

  		if (!free)

  			ptask->enqueued = true;
  		else

  			dec_queued_datagrams(dev);

  		spin_unlock_irqrestore(&dev->lock, flags);

  		goto out;

  	}

  
  	fw_send_request(dev->card, &ptask->transaction,
  			TCODE_WRITE_BLOCK_REQUEST, ptask->dest_node,
  			ptask->generation, ptask->speed, ptask->fifo_addr,
  			ptask->skb->data, tx_len, fwnet_write_complete, ptask);

  	spin_lock_irqsave(&dev->lock, flags);

  
  	/* If the AT tasklet already ran, we may be last user. */

  	free = (ptask->outstanding_pkts == 0 && !ptask->enqueued);

  	if (!free)

  		ptask->enqueued = true;
  	else

  		dec_queued_datagrams(dev);

  	spin_unlock_irqrestore(&dev->lock, flags);

  	dev->netdev->trans_start = jiffies;

   out:
  	if (free)
  		fwnet_free_ptask(ptask);

  	return 0;
  }

  static int fwnet_broadcast_start(struct fwnet_device *dev)
  {

  	struct fw_iso_context *context;
  	int retval;
  	unsigned num_packets;
  	unsigned max_receive;
  	struct fw_iso_packet packet;
  	unsigned long offset;
  	unsigned u;

  	if (dev->local_fifo == FWNET_NO_FIFO_ADDR) {

  		dev->handler.length = 4096;
  		dev->handler.address_callback = fwnet_receive_packet;
  		dev->handler.callback_data = dev;

  		retval = fw_core_add_address_handler(&dev->handler,
  					&fw_high_memory_region);

  		if (retval < 0)

  			goto failed_initial;

  
  		dev->local_fifo = dev->handler.offset;

  	}

  	max_receive = 1U << (dev->card->max_receive + 1);
  	num_packets = (FWNET_ISO_PAGE_COUNT * PAGE_SIZE) / max_receive;
  
  	if (!dev->broadcast_rcv_context) {

  		void **ptrptr;

  		context = fw_iso_context_create(dev->card,
  		    FW_ISO_CONTEXT_RECEIVE, IEEE1394_BROADCAST_CHANNEL,
  		    dev->card->link_speed, 8, fwnet_receive_broadcast, dev);

  		if (IS_ERR(context)) {
  			retval = PTR_ERR(context);
  			goto failed_context_create;
  		}

  
  		retval = fw_iso_buffer_init(&dev->broadcast_rcv_buffer,
  		    dev->card, FWNET_ISO_PAGE_COUNT, DMA_FROM_DEVICE);
  		if (retval < 0)

  			goto failed_buffer_init;

  
  		ptrptr = kmalloc(sizeof(void *) * num_packets, GFP_KERNEL);
  		if (!ptrptr) {

  			retval = -ENOMEM;
  			goto failed_ptrs_alloc;
  		}

  
  		dev->broadcast_rcv_buffer_ptrs = ptrptr;
  		for (u = 0; u < FWNET_ISO_PAGE_COUNT; u++) {

  			void *ptr;
  			unsigned v;

  			ptr = kmap(dev->broadcast_rcv_buffer.pages[u]);
  			for (v = 0; v < num_packets / FWNET_ISO_PAGE_COUNT; v++)
  				*ptrptr++ = (void *)
  						((char *)ptr + v * max_receive);

  		}

  		dev->broadcast_rcv_context = context;
  	} else {
  		context = dev->broadcast_rcv_context;
  	}

  
  	packet.payload_length = max_receive;
  	packet.interrupt = 1;
  	packet.skip = 0;
  	packet.tag = 3;
  	packet.sy = 0;

  	packet.header_length = IEEE1394_GASP_HDR_SIZE;

  	offset = 0;

  
  	for (u = 0; u < num_packets; u++) {
  		retval = fw_iso_context_queue(context, &packet,
  				&dev->broadcast_rcv_buffer, offset);
  		if (retval < 0)

  			goto failed_rcv_queue;

  		offset += max_receive;
  	}

  	dev->num_broadcast_rcv_ptrs = num_packets;
  	dev->rcv_buffer_size = max_receive;
  	dev->broadcast_rcv_next_ptr = 0U;
  	retval = fw_iso_context_start(context, -1, 0,
  			FW_ISO_CONTEXT_MATCH_ALL_TAGS); /* ??? sync */
  	if (retval < 0)

  		goto failed_rcv_queue;

  
  	/* FIXME: adjust it according to the min. speed of all known peers? */
  	dev->broadcast_xmt_max_payload = IEEE1394_MAX_PAYLOAD_S100
  			- IEEE1394_GASP_HDR_SIZE - RFC2374_UNFRAG_HDR_SIZE;
  	dev->broadcast_state = FWNET_BROADCAST_RUNNING;

  	return 0;
  
   failed_rcv_queue:

  	kfree(dev->broadcast_rcv_buffer_ptrs);
  	dev->broadcast_rcv_buffer_ptrs = NULL;

   failed_ptrs_alloc:

  	fw_iso_buffer_destroy(&dev->broadcast_rcv_buffer, dev->card);

   failed_buffer_init:

  	fw_iso_context_destroy(context);
  	dev->broadcast_rcv_context = NULL;

   failed_context_create:

  	fw_core_remove_address_handler(&dev->handler);

   failed_initial:

  	dev->local_fifo = FWNET_NO_FIFO_ADDR;

  	return retval;
  }

  static void set_carrier_state(struct fwnet_device *dev)
  {
  	if (dev->peer_count > 1)
  		netif_carrier_on(dev->netdev);
  	else
  		netif_carrier_off(dev->netdev);
  }

  /* ifup */
  static int fwnet_open(struct net_device *net)
  {
  	struct fwnet_device *dev = netdev_priv(net);

  	int ret;

  	if (dev->broadcast_state == FWNET_BROADCAST_ERROR) {
  		ret = fwnet_broadcast_start(dev);

  		if (ret)
  			return ret;
  	}

  	netif_start_queue(net);

  	spin_lock_irq(&dev->lock);
  	set_carrier_state(dev);
  	spin_unlock_irq(&dev->lock);

  	return 0;
  }

  /* ifdown */
  static int fwnet_stop(struct net_device *net)

  {

  	netif_stop_queue(net);
  
  	/* Deallocate iso context for use by other applications? */

  	return 0;
  }

  static netdev_tx_t fwnet_tx(struct sk_buff *skb, struct net_device *net)

  {

  	struct fwnet_header hdr_buf;
  	struct fwnet_device *dev = netdev_priv(net);

  	__be16 proto;
  	u16 dest_node;

  	unsigned max_payload;
  	u16 dg_size;
  	u16 *datagram_label_ptr;

  	struct fwnet_packet_task *ptask;

  	struct fwnet_peer *peer;
  	unsigned long flags;

  	spin_lock_irqsave(&dev->lock, flags);
  
  	/* Can this happen? */
  	if (netif_queue_stopped(dev->netdev)) {
  		spin_unlock_irqrestore(&dev->lock, flags);
  
  		return NETDEV_TX_BUSY;
  	}

  	ptask = kmem_cache_alloc(fwnet_packet_task_cache, GFP_ATOMIC);

  	if (ptask == NULL)
  		goto fail;
  
  	skb = skb_share_check(skb, GFP_ATOMIC);
  	if (!skb)
  		goto fail;
  
  	/*

  	 * Make a copy of the driver-specific header.

  	 * We might need to rebuild the header on tx failure.
  	 */
  	memcpy(&hdr_buf, skb->data, sizeof(hdr_buf));
  	skb_pull(skb, sizeof(hdr_buf));
  
  	proto = hdr_buf.h_proto;
  	dg_size = skb->len;
  
  	/*
  	 * Set the transmission type for the packet.  ARP packets and IP
  	 * broadcast packets are sent via GASP.
  	 */

  	if (memcmp(hdr_buf.h_dest, net->broadcast, FWNET_ALEN) == 0

  	    || proto == htons(ETH_P_ARP)

  	    || (proto == htons(ETH_P_IP)
  		&& IN_MULTICAST(ntohl(ip_hdr(skb)->daddr)))) {

  		max_payload        = dev->broadcast_xmt_max_payload;

  		datagram_label_ptr = &dev->broadcast_xmt_datagramlabel;

  		ptask->fifo_addr   = FWNET_NO_FIFO_ADDR;
  		ptask->generation  = 0;
  		ptask->dest_node   = IEEE1394_ALL_NODES;
  		ptask->speed       = SCODE_100;

  	} else {

  		__be64 guid = get_unaligned((__be64 *)hdr_buf.h_dest);

  		u8 generation;

  		peer = fwnet_peer_find_by_guid(dev, be64_to_cpu(guid));

  		if (!peer || peer->fifo == FWNET_NO_FIFO_ADDR)

  			goto fail;

  		generation         = peer->generation;
  		dest_node          = peer->node_id;
  		max_payload        = peer->max_payload;

  		datagram_label_ptr = &peer->datagram_label;

  		ptask->fifo_addr   = peer->fifo;
  		ptask->generation  = generation;
  		ptask->dest_node   = dest_node;
  		ptask->speed       = peer->speed;

  	}
  
  	/* If this is an ARP packet, convert it */
  	if (proto == htons(ETH_P_ARP)) {

  		struct arphdr *arp = (struct arphdr *)skb->data;
  		unsigned char *arp_ptr = (unsigned char *)(arp + 1);

  		struct rfc2734_arp *arp1394 = (struct rfc2734_arp *)skb->data;
  		__be32 ipaddr;
  
  		ipaddr = get_unaligned((__be32 *)(arp_ptr + FWNET_ALEN));
  
  		arp1394->hw_addr_len    = RFC2734_HW_ADDR_LEN;
  		arp1394->max_rec        = dev->card->max_receive;
  		arp1394->sspd		= dev->card->link_speed;
  
  		put_unaligned_be16(dev->local_fifo >> 32,
  				   &arp1394->fifo_hi);
  		put_unaligned_be32(dev->local_fifo & 0xffffffff,
  				   &arp1394->fifo_lo);
  		put_unaligned(ipaddr, &arp1394->sip);

  	}

  
  	ptask->hdr.w0 = 0;
  	ptask->hdr.w1 = 0;
  	ptask->skb = skb;

  	ptask->dev = dev;

  	/* Does it all fit in one packet? */

  	if (dg_size <= max_payload) {
  		fwnet_make_uf_hdr(&ptask->hdr, ntohs(proto));

  		ptask->outstanding_pkts = 1;

  		max_payload = dg_size + RFC2374_UNFRAG_HDR_SIZE;

  	} else {
  		u16 datagram_label;

  		max_payload -= RFC2374_FRAG_OVERHEAD;

  		datagram_label = (*datagram_label_ptr)++;

  		fwnet_make_ff_hdr(&ptask->hdr, ntohs(proto), dg_size,
  				  datagram_label);

  		ptask->outstanding_pkts = DIV_ROUND_UP(dg_size, max_payload);

  		max_payload += RFC2374_FRAG_HDR_SIZE;

  	}

  	if (++dev->queued_datagrams == FWNET_MAX_QUEUED_DATAGRAMS)
  		netif_stop_queue(dev->netdev);

  	spin_unlock_irqrestore(&dev->lock, flags);

  	ptask->max_payload = max_payload;

  	ptask->enqueued    = 0;

  	fwnet_send_packet(ptask);

  	return NETDEV_TX_OK;
  
   fail:

  	spin_unlock_irqrestore(&dev->lock, flags);

  	if (ptask)

  		kmem_cache_free(fwnet_packet_task_cache, ptask);

  
  	if (skb != NULL)
  		dev_kfree_skb(skb);

  	net->stats.tx_dropped++;
  	net->stats.tx_errors++;

  
  	/*
  	 * FIXME: According to a patch from 2003-02-26, "returning non-zero
  	 * causes serious problems" here, allegedly.  Before that patch,
  	 * -ERRNO was returned which is not appropriate under Linux 2.6.
  	 * Perhaps more needs to be done?  Stop the queue in serious
  	 * conditions and restart it elsewhere?
  	 */
  	return NETDEV_TX_OK;
  }

  static int fwnet_change_mtu(struct net_device *net, int new_mtu)
  {

  	if (new_mtu < 68)
  		return -EINVAL;

  	net->mtu = new_mtu;

  	return 0;
  }

  static const struct ethtool_ops fwnet_ethtool_ops = {
  	.get_link	= ethtool_op_get_link,
  };

  static const struct net_device_ops fwnet_netdev_ops = {
  	.ndo_open       = fwnet_open,
  	.ndo_stop	= fwnet_stop,
  	.ndo_start_xmit = fwnet_tx,

  	.ndo_change_mtu = fwnet_change_mtu,

  };

  static void fwnet_init_dev(struct net_device *net)
  {
  	net->header_ops		= &fwnet_header_ops;
  	net->netdev_ops		= &fwnet_netdev_ops;

  	net->watchdog_timeo	= 2 * HZ;

  	net->flags		= IFF_BROADCAST | IFF_MULTICAST;
  	net->features		= NETIF_F_HIGHDMA;
  	net->addr_len		= FWNET_ALEN;
  	net->hard_header_len	= FWNET_HLEN;
  	net->type		= ARPHRD_IEEE1394;

  	net->tx_queue_len	= FWNET_TX_QUEUE_LEN;

  	net->ethtool_ops	= &fwnet_ethtool_ops;

  }

  /* caller must hold fwnet_device_mutex */
  static struct fwnet_device *fwnet_dev_find(struct fw_card *card)
  {
  	struct fwnet_device *dev;
  
  	list_for_each_entry(dev, &fwnet_device_list, dev_link)
  		if (dev->card == card)
  			return dev;
  
  	return NULL;
  }
  
  static int fwnet_add_peer(struct fwnet_device *dev,
  			  struct fw_unit *unit, struct fw_device *device)
  {
  	struct fwnet_peer *peer;
  
  	peer = kmalloc(sizeof(*peer), GFP_KERNEL);
  	if (!peer)
  		return -ENOMEM;

  	dev_set_drvdata(&unit->device, peer);

  	peer->dev = dev;
  	peer->guid = (u64)device->config_rom[3] << 32 | device->config_rom[4];
  	peer->fifo = FWNET_NO_FIFO_ADDR;

  	peer->ip = 0;

  	INIT_LIST_HEAD(&peer->pd_list);
  	peer->pdg_size = 0;
  	peer->datagram_label = 0;
  	peer->speed = device->max_speed;
  	peer->max_payload = fwnet_max_payload(device->max_rec, peer->speed);
  
  	peer->generation = device->generation;
  	smp_rmb();
  	peer->node_id = device->node_id;
  
  	spin_lock_irq(&dev->lock);
  	list_add_tail(&peer->peer_link, &dev->peer_list);

  	dev->peer_count++;

  	set_carrier_state(dev);

  	spin_unlock_irq(&dev->lock);
  
  	return 0;
  }

  static int fwnet_probe(struct device *_dev)
  {
  	struct fw_unit *unit = fw_unit(_dev);
  	struct fw_device *device = fw_parent_device(unit);
  	struct fw_card *card = device->card;
  	struct net_device *net;

  	bool allocated_netdev = false;

  	struct fwnet_device *dev;

  	unsigned max_mtu;

  	int ret;

  	mutex_lock(&fwnet_device_mutex);

  	dev = fwnet_dev_find(card);
  	if (dev) {

  		net = dev->netdev;
  		goto have_dev;

  	}

  	net = alloc_netdev(sizeof(*dev), "firewire%d", fwnet_init_dev);
  	if (net == NULL) {

  		ret = -ENOMEM;

  		goto out;
  	}

  	allocated_netdev = true;

  	SET_NETDEV_DEV(net, card->device);
  	dev = netdev_priv(net);

  	spin_lock_init(&dev->lock);
  	dev->broadcast_state = FWNET_BROADCAST_ERROR;
  	dev->broadcast_rcv_context = NULL;
  	dev->broadcast_xmt_max_payload = 0;
  	dev->broadcast_xmt_datagramlabel = 0;

  	dev->local_fifo = FWNET_NO_FIFO_ADDR;

  	dev->queued_datagrams = 0;

  	INIT_LIST_HEAD(&dev->peer_list);

  	dev->card = card;

  	dev->netdev = net;

  
  	/*
  	 * Use the RFC 2734 default 1500 octets or the maximum payload
  	 * as initial MTU
  	 */
  	max_mtu = (1 << (card->max_receive + 1))