net.c

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/*
 * IPv4 over IEEE 1394, per RFC 2734
 *
 * Copyright (C) 2009 Jay Fenlason <[email protected]>
 *
 * 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);

    dev_notice(&skb->dev->dev, "unable to resolve type %04x addresses\n",
           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) {
        dev_err(&pd->skb->dev->dev, "out of memory\n");
        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:
    dev_err(&net->dev, "out of memory\n");

    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) {
            dev_notice(&net->dev, "sspd %x out of range\n", 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) {
            dev_notice(&net->dev,
                   "no peer for ARP packet from %016llx\n",
                   (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)) {
            dev_err(&net->dev, "out of memory\n");
            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) {
        dev_err(&dev->netdev->dev, "incoming packet failure\n");
        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
        dev_err(&dev->netdev->dev, "requeue failed\n");
}

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:
            dev_err(&dev->netdev->dev,
                "outstanding packet %x lf %x, header %x,%x\n",
                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) {
            dev_err(&ptask->dev->netdev->dev,
                "fwnet_write_complete failed: %x (skipped %d)\n",
                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))
          - sizeof(struct rfc2734_header) - IEEE1394_GASP_HDR_SIZE;
    net->mtu = min(1500U, max_mtu);

    /* Set our hardware address while we're at it */
    put_unaligned_be64(card->guid, net->dev_addr);
    put_unaligned_be64(~0ULL, net->broadcast);
    ret = register_netdev(net);
    if (ret)
        goto out;

    list_add_tail(&dev->dev_link, &fwnet_device_list);
    dev_notice(&net->dev, "IPv4 over IEEE 1394 on card %s\n",
           dev_name(card->device));
 have_dev:
    ret = fwnet_add_peer(dev, unit, device);
    if (ret && allocated_netdev) {
        unregister_netdev(net);
        list_del(&dev->dev_link);
    }
 out:
    if (ret && allocated_netdev)
        free_netdev(net);

    mutex_unlock(&fwnet_device_mutex);

    return ret;
}

static void fwnet_remove_peer(struct fwnet_peer *peer, struct fwnet_device *dev)
{
    struct fwnet_partial_datagram *pd, *pd_next;

    spin_lock_irq(&dev->lock);
    list_del(&peer->peer_link);
    dev->peer_count--;
    set_carrier_state(dev);
    spin_unlock_irq(&dev->lock);

    list_for_each_entry_safe(pd, pd_next, &peer->pd_list, pd_link)
        fwnet_pd_delete(pd);

    kfree(peer);
}

static int fwnet_remove(struct device *_dev)
{
    struct fwnet_peer *peer = dev_get_drvdata(_dev);
    struct fwnet_device *dev = peer->dev;
    struct net_device *net;
    int i;

    mutex_lock(&fwnet_device_mutex);

    net = dev->netdev;
    if (net && peer->ip)
        arp_invalidate(net, peer->ip);

    fwnet_remove_peer(peer, dev);

    if (list_empty(&dev->peer_list)) {
        unregister_netdev(net);

        if (dev->local_fifo != FWNET_NO_FIFO_ADDR)
            fw_core_remove_address_handler(&dev->handler);
        if (dev->broadcast_rcv_context) {
            fw_iso_context_stop(dev->broadcast_rcv_context);
            fw_iso_buffer_destroy(&dev->broadcast_rcv_buffer,
                          dev->card);
            fw_iso_context_destroy(dev->broadcast_rcv_context);
        }
        for (i = 0; dev->queued_datagrams && i < 5; i++)
            ssleep(1);
        WARN_ON(dev->queued_datagrams);
        list_del(&dev->dev_link);

        free_netdev(net);
    }

    mutex_unlock(&fwnet_device_mutex);

    return 0;
}

/*
 * FIXME abort partially sent fragmented datagrams,
 * discard partially received fragmented datagrams
 */
static void fwnet_update(struct fw_unit *unit)
{
    struct fw_device *device = fw_parent_device(unit);
    struct fwnet_peer *peer = dev_get_drvdata(&unit->device);
    int generation;

    generation = device->generation;

    spin_lock_irq(&peer->dev->lock);
    peer->node_id    = device->node_id;
    peer->generation = generation;
    spin_unlock_irq(&peer->dev->lock);
}

static const struct ieee1394_device_id fwnet_id_table[] = {
    {
        .match_flags  = IEEE1394_MATCH_SPECIFIER_ID |
                IEEE1394_MATCH_VERSION,
        .specifier_id = IANA_SPECIFIER_ID,
        .version      = RFC2734_SW_VERSION,
    },
    { }
};

static struct fw_driver fwnet_driver = {
    .driver = {
        .owner  = THIS_MODULE,
        .name   = KBUILD_MODNAME,
        .bus    = &fw_bus_type,
        .probe  = fwnet_probe,
        .remove = fwnet_remove,
    },
    .update   = fwnet_update,
    .id_table = fwnet_id_table,
};

static const u32 rfc2374_unit_directory_data[] = {
    0x00040000, /* directory_length     */
    0x1200005e, /* unit_specifier_id: IANA  */
    0x81000003, /* textual descriptor offset    */
    0x13000001, /* unit_sw_version: RFC 2734    */
    0x81000005, /* textual descriptor offset    */
    0x00030000, /* descriptor_length        */
    0x00000000, /* text             */
    0x00000000, /* minimal ASCII, en        */
    0x49414e41, /* I A N A          */
    0x00030000, /* descriptor_length        */
    0x00000000, /* text             */
    0x00000000, /* minimal ASCII, en        */
    0x49507634, /* I P v 4          */
};

static struct fw_descriptor rfc2374_unit_directory = {
    .length = ARRAY_SIZE(rfc2374_unit_directory_data),
    .key    = (CSR_DIRECTORY | CSR_UNIT) << 24,
    .data   = rfc2374_unit_directory_data
};

static int __init fwnet_init(void)
{
    int err;

    err = fw_core_add_descriptor(&rfc2374_unit_directory);
    if (err)
        return err;

    fwnet_packet_task_cache = kmem_cache_create("packet_task",
            sizeof(struct fwnet_packet_task), 0, 0, NULL);
    if (!fwnet_packet_task_cache) {
        err = -ENOMEM;
        goto out;
    }

    err = driver_register(&fwnet_driver.driver);
    if (!err)
        return 0;

    kmem_cache_destroy(fwnet_packet_task_cache);
out:
    fw_core_remove_descriptor(&rfc2374_unit_directory);

    return err;
}
module_init(fwnet_init);

static void __exit fwnet_cleanup(void)
{
    driver_unregister(&fwnet_driver.driver);
    kmem_cache_destroy(fwnet_packet_task_cache);
    fw_core_remove_descriptor(&rfc2374_unit_directory);
}
module_exit(fwnet_cleanup);

MODULE_AUTHOR("Jay Fenlason <[email protected]>");
MODULE_DESCRIPTION("IPv4 over IEEE1394 as per RFC 2734");
MODULE_LICENSE("GPL");
MODULE_DEVICE_TABLE(ieee1394, fwnet_id_table);