net: add ETH_P_802_3_MIN

[mirror_ubuntu-jammy-kernel.git] / drivers / firewire / net.c

/*
 * IPv4 over IEEE 1394, per RFC 2734
 * IPv6 over IEEE 1394, per RFC 3146
 *
 * 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>
#include <net/firewire.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 RFC3146_SW_VERSION              0x000002U

#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    */

static bool fwnet_hwaddr_is_multicast(u8 *ha)
{
        return !!(*ha & 1);
}

/* 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;

        /* 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;
};

/*
 * Get fifo address embedded in hwaddr
 */
static __u64 fwnet_hwaddr_fifo(union fwnet_hwaddr *ha)
{
        return (u64)get_unaligned_be16(&ha->uc.fifo_hi) << 32
               | get_unaligned_be32(&ha->uc.fifo_lo);
}

/*
 * 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 + HH_DATA_OFF(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 + HH_DATA_OFF(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 + LL_RESERVED_SPACE(net));
        if (new->skb == NULL)
                goto fail_w_fi;

        skb_reserve(new->skb, LL_RESERVED_SPACE(net));
        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;
        int status;
        __be64 guid;

        switch (ether_type) {
        case ETH_P_ARP:
        case ETH_P_IP:
#if IS_ENABLED(CONFIG_IPV6)
        case ETH_P_IPV6:
#endif
                break;
        default:
                goto err;
        }

        dev = netdev_priv(net);
        /* Write metadata, and then pass to the receive level */
        skb->dev = net;
        skb->ip_summed = CHECKSUM_NONE;

        /*
         * Parse the encapsulation header. This actually does the job of
         * converting to an ethernet-like pseudo frame header.
         */
        guid = cpu_to_be64(dev->card->guid);
        if (dev_hard_header(skb, net, ether_type,
                           is_broadcast ? net->broadcast : net->dev_addr,
                           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 (fwnet_hwaddr_is_multicast(eth->h_dest)) {
                        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) >= ETH_P_802_3_MIN) {
                        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;

 err:
        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 + LL_RESERVED_SPACE(net));
                if (unlikely(!skb)) {
                        dev_err(&net->dev, "out of memory\n");
                        net->stats.rx_dropped++;

                        return -ENOMEM;
                }
                skb_reserve(skb, LL_RESERVED_SPACE(net));
                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;
        __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;
        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
#if IS_ENABLED(CONFIG_IPV6)
             || ver == RFC3146_SW_VERSION
#endif
            )) {
                buf_ptr += 2;
                length -= IEEE1394_GASP_HDR_SIZE;
                fwnet_incoming_packet(dev, buf_ptr, length, source_node_id,
                                      context->card->generation, 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;
                }

                if (ptask->dest_node == IEEE1394_ALL_NODES) {
                        skb_pull(skb,
                                 ptask->max_payload + IEEE1394_GASP_HDR_SIZE);
                } else {
                        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;
                unsigned int sw_version;

                /* ptask->generation may not have been set yet */
                generation = dev->card->generation;
                smp_rmb();
                node_id = dev->card->node_id;

                switch (ptask->skb->protocol) {
                default:
                        sw_version = RFC2734_SW_VERSION;
                        break;
#if IS_ENABLED(CONFIG_IPV6)
                case htons(ETH_P_IPV6):
                        sw_version = RFC3146_SW_VERSION;
#endif
                }

                p = skb_push(ptask->skb, IEEE1394_GASP_HDR_SIZE);
                put_unaligned_be32(node_id << 16 | IANA_SPECIFIER_ID >> 8, p);
                put_unaligned_be32((IANA_SPECIFIER_ID & 0xff) << 24
                                                | 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 void fwnet_fifo_stop(struct fwnet_device *dev)
{
        if (dev->local_fifo == FWNET_NO_FIFO_ADDR)
                return;

        fw_core_remove_address_handler(&dev->handler);
        dev->local_fifo = FWNET_NO_FIFO_ADDR;
}

static int fwnet_fifo_start(struct fwnet_device *dev)
{
        int retval;

        if (dev->local_fifo != FWNET_NO_FIFO_ADDR)
                return 0;

        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)
                return retval;

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

        return 0;
}

static void __fwnet_broadcast_stop(struct fwnet_device *dev)
{
        unsigned u;

        if (dev->broadcast_state != FWNET_BROADCAST_ERROR) {
                for (u = 0; u < FWNET_ISO_PAGE_COUNT; u++)
                        kunmap(dev->broadcast_rcv_buffer.pages[u]);
                fw_iso_buffer_destroy(&dev->broadcast_rcv_buffer, dev->card);
        }
        if (dev->broadcast_rcv_context) {
                fw_iso_context_destroy(dev->broadcast_rcv_context);
                dev->broadcast_rcv_context = NULL;
        }
        kfree(dev->broadcast_rcv_buffer_ptrs);
        dev->broadcast_rcv_buffer_ptrs = NULL;
        dev->broadcast_state = FWNET_BROADCAST_ERROR;
}

static void fwnet_broadcast_stop(struct fwnet_device *dev)
{
        if (dev->broadcast_state == FWNET_BROADCAST_ERROR)
                return;
        fw_iso_context_stop(dev->broadcast_rcv_context);
        __fwnet_broadcast_stop(dev);
}

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;
        void **ptrptr;
        unsigned u;

        if (dev->broadcast_state != FWNET_BROADCAST_ERROR)
                return 0;

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

        ptrptr = kmalloc(sizeof(void *) * num_packets, GFP_KERNEL);
        if (!ptrptr) {
                retval = -ENOMEM;
                goto failed;
        }
        dev->broadcast_rcv_buffer_ptrs = 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;
        }

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

        dev->broadcast_state = FWNET_BROADCAST_STOPPED;

        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;

        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;

                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;

        /* 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:
        __fwnet_broadcast_stop(dev);
        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;

        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)
{
        struct fwnet_device *dev = netdev_priv(net);

        netif_stop_queue(net);
        fwnet_broadcast_stop(dev);

        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));
        proto = hdr_buf.h_proto;

        switch (proto) {
        case htons(ETH_P_ARP):
        case htons(ETH_P_IP):
#if IS_ENABLED(CONFIG_IPV6)
        case htons(ETH_P_IPV6):
#endif
                break;
        default:
                goto fail;
        }

        skb_pull(skb, sizeof(hdr_buf));
        dg_size = skb->len;

        /*
         * Set the transmission type for the packet.  ARP packets and IP
         * broadcast packets are sent via GASP.
         */
        if (fwnet_hwaddr_is_multicast(hdr_buf.h_dest)) {
                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 {
                union fwnet_hwaddr *ha = (union fwnet_hwaddr *)hdr_buf.h_dest;
                __be64 guid = get_unaligned(&ha->uc.uniq_id);
                u8 generation;

                peer = fwnet_peer_find_by_guid(dev, be64_to_cpu(guid));
                if (!peer)
                        goto fail;

                generation         = peer->generation;
                dest_node          = peer->node_id;
                max_payload        = peer->max_payload;
                datagram_label_ptr = &peer->datagram_label;

                ptask->fifo_addr   = fwnet_hwaddr_fifo(ha);
                ptask->generation  = generation;
                ptask->dest_node   = dest_node;
                ptask->speed       = peer->speed;
        }

        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];
        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;
        union fwnet_hwaddr *ha;

        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;

        ret = fwnet_fifo_start(dev);
        if (ret < 0)
                goto out;
        dev->local_fifo = dev->handler.offset;

        /*
         * 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 */
        ha = (union fwnet_hwaddr *)net->dev_addr;
        put_unaligned_be64(card->guid, &ha->uc.uniq_id);
        ha->uc.max_rec = dev->card->max_receive;
        ha->uc.sspd = dev->card->link_speed;
        put_unaligned_be16(dev->local_fifo >> 32, &ha->uc.fifo_hi);
        put_unaligned_be32(dev->local_fifo & 0xffffffff, &ha->uc.fifo_lo);

        memset(net->broadcast, -1, net->addr_len);

        ret = register_netdev(net);
        if (ret)
                goto out;

        list_add_tail(&dev->dev_link, &fwnet_device_list);
        dev_notice(&net->dev, "IP 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:
                fwnet_fifo_stop(dev);
                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;

        fwnet_remove_peer(peer, dev);

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

                fwnet_fifo_stop(dev);

                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,
        },
#if IS_ENABLED(CONFIG_IPV6)
        {
                .match_flags  = IEEE1394_MATCH_SPECIFIER_ID |
                                IEEE1394_MATCH_VERSION,
                .specifier_id = IANA_SPECIFIER_ID,
                .version      = RFC3146_SW_VERSION,
        },
#endif
        { }
};

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
};

#if IS_ENABLED(CONFIG_IPV6)
static const u32 rfc3146_unit_directory_data[] = {
        0x00040000,     /* directory_length             */
        0x1200005e,     /* unit_specifier_id: IANA      */
        0x81000003,     /* textual descriptor offset    */
        0x13000002,     /* unit_sw_version: RFC 3146    */
        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            */
        0x49507636,     /* I P v 6                      */
};

static struct fw_descriptor rfc3146_unit_directory = {
        .length = ARRAY_SIZE(rfc3146_unit_directory_data),
        .key    = (CSR_DIRECTORY | CSR_UNIT) << 24,
        .data   = rfc3146_unit_directory_data
};
#endif

static int __init fwnet_init(void)
{
        int err;

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

#if IS_ENABLED(CONFIG_IPV6)
        err = fw_core_add_descriptor(&rfc3146_unit_directory);
        if (err)
                goto out;
#endif

        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 out2;
        }

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

        kmem_cache_destroy(fwnet_packet_task_cache);
out2:
#if IS_ENABLED(CONFIG_IPV6)
        fw_core_remove_descriptor(&rfc3146_unit_directory);
out:
#endif
        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);
#if IS_ENABLED(CONFIG_IPV6)
        fw_core_remove_descriptor(&rfc3146_unit_directory);
#endif
        fw_core_remove_descriptor(&rfc2374_unit_directory);
}
module_exit(fwnet_cleanup);

MODULE_AUTHOR("Jay Fenlason <fenlason@redhat.com>");
MODULE_DESCRIPTION("IP over IEEE1394 as per RFC 2734/3146");
MODULE_LICENSE("GPL");
MODULE_DEVICE_TABLE(ieee1394, fwnet_id_table);