/*
  Experimental ethernet netdevice using ATM AAL5 as underlying carrier
  (RFC1483 obsoleted by RFC2684) for Linux 2.4
  Author: Marcell GAL, 2000, XDSL Ltd, Hungary
  */
  
  #include <linux/module.h>

  #include <linux/init.h>
  #include <linux/kernel.h>
  #include <linux/list.h>
  #include <linux/netdevice.h>
  #include <linux/skbuff.h>
  #include <linux/etherdevice.h>
  #include <linux/rtnetlink.h>
  #include <linux/ip.h>
  #include <asm/uaccess.h>
  #include <net/arp.h>
  #include <linux/atm.h>
  #include <linux/atmdev.h>

  #include <linux/capability.h>

  #include <linux/seq_file.h>
  
  #include <linux/atmbr2684.h>
  
  #include "common.h"

  
  /*
   * Define this to use a version of the code which interacts with the higher
   * layers in a more intellegent way, by always reserving enough space for
   * our header at the begining of the packet.  However, there may still be
   * some problems with programs like tcpdump.  In 2.5 we'll sort out what
   * we need to do to get this perfect.  For now we just will copy the packet
   * if we need space for the header
   */
  /* #define FASTER_VERSION */
  
  #ifdef DEBUG
  #define DPRINTK(format, args...) printk(KERN_DEBUG "br2684: " format, ##args)
  #else
  #define DPRINTK(format, args...)
  #endif
  
  #ifdef SKB_DEBUG
  static void skb_debug(const struct sk_buff *skb)
  {
  #define NUM2PRINT 50
  	char buf[NUM2PRINT * 3 + 1];	/* 3 chars per byte */
  	int i = 0;
  	for (i = 0; i < skb->len && i < NUM2PRINT; i++) {
  		sprintf(buf + i * 3, "%2.2x ", 0xff & skb->data[i]);
  	}
  	printk(KERN_DEBUG "br2684: skb: %s
  ", buf);
  }
  #else
  #define skb_debug(skb)	do {} while (0)
  #endif
  
  static unsigned char llc_oui_pid_pad[] =
      { 0xAA, 0xAA, 0x03, 0x00, 0x80, 0xC2, 0x00, 0x07, 0x00, 0x00 };
  #define PADLEN	(2)
  
  enum br2684_encaps {
  	e_vc  = BR2684_ENCAPS_VC,
  	e_llc = BR2684_ENCAPS_LLC,
  };
  
  struct br2684_vcc {
  	struct atm_vcc  *atmvcc;
  	struct net_device *device;
  	/* keep old push,pop functions for chaining */
  	void (*old_push)(struct atm_vcc *vcc,struct sk_buff *skb);
  	/* void (*old_pop)(struct atm_vcc *vcc,struct sk_buff *skb); */
  	enum br2684_encaps encaps;
  	struct list_head brvccs;
  #ifdef CONFIG_ATM_BR2684_IPFILTER
  	struct br2684_filter filter;
  #endif /* CONFIG_ATM_BR2684_IPFILTER */
  #ifndef FASTER_VERSION
  	unsigned copies_needed, copies_failed;
  #endif /* FASTER_VERSION */
  };
  
  struct br2684_dev {
  	struct net_device *net_dev;
  	struct list_head br2684_devs;
  	int number;
  	struct list_head brvccs; /* one device <=> one vcc (before xmas) */
  	struct net_device_stats stats;
  	int mac_was_set;
  };
  
  /*
   * This lock should be held for writing any time the list of devices or
   * their attached vcc's could be altered.  It should be held for reading
   * any time these are being queried.  Note that we sometimes need to
   * do read-locking under interrupt context, so write locking must block
   * the current CPU's interrupts
   */
  static DEFINE_RWLOCK(devs_lock);
  
  static LIST_HEAD(br2684_devs);
  
  static inline struct br2684_dev *BRPRIV(const struct net_device *net_dev)
  {
  	return (struct br2684_dev *) net_dev->priv;
  }
  
  static inline struct net_device *list_entry_brdev(const struct list_head *le)
  {
  	return list_entry(le, struct br2684_dev, br2684_devs)->net_dev;
  }
  
  static inline struct br2684_vcc *BR2684_VCC(const struct atm_vcc *atmvcc)
  {
  	return (struct br2684_vcc *) (atmvcc->user_back);
  }
  
  static inline struct br2684_vcc *list_entry_brvcc(const struct list_head *le)
  {
  	return list_entry(le, struct br2684_vcc, brvccs);
  }
  
  /* Caller should hold read_lock(&devs_lock) */
  static struct net_device *br2684_find_dev(const struct br2684_if_spec *s)
  {
  	struct list_head *lh;
  	struct net_device *net_dev;
  	switch (s->method) {
  	case BR2684_FIND_BYNUM:
  		list_for_each(lh, &br2684_devs) {
  			net_dev = list_entry_brdev(lh);
  			if (BRPRIV(net_dev)->number == s->spec.devnum)
  				return net_dev;
  		}
  		break;
  	case BR2684_FIND_BYIFNAME:
  		list_for_each(lh, &br2684_devs) {
  			net_dev = list_entry_brdev(lh);
  			if (!strncmp(net_dev->name, s->spec.ifname, IFNAMSIZ))
  				return net_dev;
  		}
  		break;
  	}
  	return NULL;
  }
  
  /*
   * Send a packet out a particular vcc.  Not to useful right now, but paves
   * the way for multiple vcc's per itf.  Returns true if we can send,
   * otherwise false
   */
  static int br2684_xmit_vcc(struct sk_buff *skb, struct br2684_dev *brdev,
  	struct br2684_vcc *brvcc)
  {
  	struct atm_vcc *atmvcc;
  #ifdef FASTER_VERSION
  	if (brvcc->encaps == e_llc)
  		memcpy(skb_push(skb, 8), llc_oui_pid_pad, 8);
  	/* last 2 bytes of llc_oui_pid_pad are managed by header routines;
  	   yes, you got it: 8 + 2 = sizeof(llc_oui_pid_pad)
  	 */
  #else
  	int minheadroom = (brvcc->encaps == e_llc) ? 10 : 2;
  	if (skb_headroom(skb) < minheadroom) {
  		struct sk_buff *skb2 = skb_realloc_headroom(skb, minheadroom);
  		brvcc->copies_needed++;
  		dev_kfree_skb(skb);
  		if (skb2 == NULL) {
  			brvcc->copies_failed++;
  			return 0;
  		}
  		skb = skb2;
  	}
  	skb_push(skb, minheadroom);
  	if (brvcc->encaps == e_llc)

  		skb_copy_to_linear_data(skb, llc_oui_pid_pad, 10);

  	else
  		memset(skb->data, 0, 2);
  #endif /* FASTER_VERSION */
  	skb_debug(skb);
  
  	ATM_SKB(skb)->vcc = atmvcc = brvcc->atmvcc;
  	DPRINTK("atm_skb(%p)->vcc(%p)->dev(%p)
  ", skb, atmvcc, atmvcc->dev);
  	if (!atm_may_send(atmvcc, skb->truesize)) {

  		/* we free this here for now, because we cannot know in a higher

  			layer whether the skb point it supplied wasn't freed yet.
  			now, it always is.
  		*/
  		dev_kfree_skb(skb);
  		return 0;
  		}
  	atomic_add(skb->truesize, &sk_atm(atmvcc)->sk_wmem_alloc);
  	ATM_SKB(skb)->atm_options = atmvcc->atm_options;
  	brdev->stats.tx_packets++;
  	brdev->stats.tx_bytes += skb->len;
  	atmvcc->send(atmvcc, skb);
  	return 1;
  }
  
  static inline struct br2684_vcc *pick_outgoing_vcc(struct sk_buff *skb,
  	struct br2684_dev *brdev)
  {
  	return list_empty(&brdev->brvccs) ? NULL :
  	    list_entry_brvcc(brdev->brvccs.next); /* 1 vcc/dev right now */
  }
  
  static int br2684_start_xmit(struct sk_buff *skb, struct net_device *dev)
  {
  	struct br2684_dev *brdev = BRPRIV(dev);
  	struct br2684_vcc *brvcc;
  
  	DPRINTK("br2684_start_xmit, skb->dst=%p
  ", skb->dst);
  	read_lock(&devs_lock);
  	brvcc = pick_outgoing_vcc(skb, brdev);
  	if (brvcc == NULL) {
  		DPRINTK("no vcc attached to dev %s
  ", dev->name);
  		brdev->stats.tx_errors++;
  		brdev->stats.tx_carrier_errors++;
  		/* netif_stop_queue(dev); */
  		dev_kfree_skb(skb);
  		read_unlock(&devs_lock);

  		return 0;

  	}
  	if (!br2684_xmit_vcc(skb, brdev, brvcc)) {
  		/*
  		 * We should probably use netif_*_queue() here, but that
  		 * involves added complication.  We need to walk before
  		 * we can run
  		 */
  		/* don't free here! this pointer might be no longer valid!
  		dev_kfree_skb(skb);
  		*/
  		brdev->stats.tx_errors++;
  		brdev->stats.tx_fifo_errors++;
  	}
  	read_unlock(&devs_lock);
  	return 0;
  }
  
  static struct net_device_stats *br2684_get_stats(struct net_device *dev)
  {
  	DPRINTK("br2684_get_stats
  ");
  	return &BRPRIV(dev)->stats;
  }
  
  #ifdef FASTER_VERSION
  /*
   * These mirror eth_header and eth_header_cache.  They are not usually
   * exported for use in modules, so we grab them from net_device
   * after ether_setup() is done with it.  Bit of a hack.
   */
  static int (*my_eth_header)(struct sk_buff *, struct net_device *,
  	unsigned short, void *, void *, unsigned);
  static int (*my_eth_header_cache)(struct neighbour *, struct hh_cache *);
  
  static int
  br2684_header(struct sk_buff *skb, struct net_device *dev,
  	      unsigned short type, void *daddr, void *saddr, unsigned len)
  {
  	u16 *pad_before_eth;
  	int t = my_eth_header(skb, dev, type, daddr, saddr, len);
  	if (t > 0) {
  		pad_before_eth = (u16 *) skb_push(skb, 2);
  		*pad_before_eth = 0;
  		return dev->hard_header_len;	/* or return 16; ? */
  	} else
  		return t;
  }
  
  static int
  br2684_header_cache(struct neighbour *neigh, struct hh_cache *hh)
  {
  /* hh_data is 16 bytes long. if encaps is ether-llc we need 24, so
  xmit will add the additional header part in that case */
  	u16 *pad_before_eth = (u16 *)(hh->hh_data);
  	int t = my_eth_header_cache(neigh, hh);
  	DPRINTK("br2684_header_cache, neigh=%p, hh_cache=%p
  ", neigh, hh);
  	if (t < 0)
  		return t;
  	else {
  		*pad_before_eth = 0;
  		hh->hh_len = PADLEN + ETH_HLEN;
  	}
  	return 0;
  }
  
  /*
   * This is similar to eth_type_trans, which cannot be used because of
   * our dev->hard_header_len
   */

  static inline __be16 br_type_trans(struct sk_buff *skb, struct net_device *dev)

  {
  	struct ethhdr *eth;
  	unsigned char *rawp;
  	eth = eth_hdr(skb);

  	if (is_multicast_ether_addr(eth->h_dest)) {

  		if (!compare_ether_addr(eth->h_dest, dev->broadcast))

  			skb->pkt_type = PACKET_BROADCAST;
  		else
  			skb->pkt_type = PACKET_MULTICAST;
  	}

  	else if (compare_ether_addr(eth->h_dest, dev->dev_addr))

  		skb->pkt_type = PACKET_OTHERHOST;
  
  	if (ntohs(eth->h_proto) >= 1536)
  		return eth->h_proto;
  
  	rawp = skb->data;
  
  	/*
  	 * This is a magic hack to spot IPX packets. Older Novell breaks
  	 * the protocol design and runs IPX over 802.3 without an 802.2 LLC
  	 * layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This
  	 * won't work for fault tolerant netware but does for the rest.
  	 */
  	if (*(unsigned short *) rawp == 0xFFFF)
  		return htons(ETH_P_802_3);
  
  	/*
  	 * Real 802.2 LLC
  	 */
  	return htons(ETH_P_802_2);
  }
  #endif /* FASTER_VERSION */
  
  /*
   * We remember when the MAC gets set, so we don't override it later with
   * the ESI of the ATM card of the first VC
   */
  static int (*my_eth_mac_addr)(struct net_device *, void *);
  static int br2684_mac_addr(struct net_device *dev, void *p)
  {
  	int err = my_eth_mac_addr(dev, p);
  	if (!err)
  		BRPRIV(dev)->mac_was_set = 1;
  	return err;
  }
  
  #ifdef CONFIG_ATM_BR2684_IPFILTER
  /* this IOCTL is experimental. */
  static int br2684_setfilt(struct atm_vcc *atmvcc, void __user *arg)
  {
  	struct br2684_vcc *brvcc;
  	struct br2684_filter_set fs;
  
  	if (copy_from_user(&fs, arg, sizeof fs))
  		return -EFAULT;
  	if (fs.ifspec.method != BR2684_FIND_BYNOTHING) {
  		/*
  		 * This is really a per-vcc thing, but we can also search
  		 * by device
  		 */
  		struct br2684_dev *brdev;
  		read_lock(&devs_lock);
  		brdev = BRPRIV(br2684_find_dev(&fs.ifspec));
  		if (brdev == NULL || list_empty(&brdev->brvccs) ||
  		    brdev->brvccs.next != brdev->brvccs.prev)  /* >1 VCC */
  			brvcc = NULL;
  		else
  			brvcc = list_entry_brvcc(brdev->brvccs.next);
  		read_unlock(&devs_lock);
  		if (brvcc == NULL)
  			return -ESRCH;
  	} else
  		brvcc = BR2684_VCC(atmvcc);
  	memcpy(&brvcc->filter, &fs.filter, sizeof(brvcc->filter));
  	return 0;
  }
  
  /* Returns 1 if packet should be dropped */
  static inline int

  packet_fails_filter(__be16 type, struct br2684_vcc *brvcc, struct sk_buff *skb)

  {
  	if (brvcc->filter.netmask == 0)
  		return 0;			/* no filter in place */

  	if (type == htons(ETH_P_IP) &&

  	    (((struct iphdr *) (skb->data))->daddr & brvcc->filter.
  	     netmask) == brvcc->filter.prefix)
  		return 0;

  	if (type == htons(ETH_P_ARP))

  		return 0;
  	/* TODO: we should probably filter ARPs too.. don't want to have
  	 *   them returning values that don't make sense, or is that ok?
  	 */
  	return 1;		/* drop */
  }
  #endif /* CONFIG_ATM_BR2684_IPFILTER */
  
  static void br2684_close_vcc(struct br2684_vcc *brvcc)
  {
  	DPRINTK("removing VCC %p from dev %p
  ", brvcc, brvcc->device);
  	write_lock_irq(&devs_lock);
  	list_del(&brvcc->brvccs);
  	write_unlock_irq(&devs_lock);
  	brvcc->atmvcc->user_back = NULL;	/* what about vcc->recvq ??? */
  	brvcc->old_push(brvcc->atmvcc, NULL);	/* pass on the bad news */
  	kfree(brvcc);
  	module_put(THIS_MODULE);
  }
  
  /* when AAL5 PDU comes in: */
  static void br2684_push(struct atm_vcc *atmvcc, struct sk_buff *skb)
  {
  	struct br2684_vcc *brvcc = BR2684_VCC(atmvcc);
  	struct net_device *net_dev = brvcc->device;
  	struct br2684_dev *brdev = BRPRIV(net_dev);
  	int plen = sizeof(llc_oui_pid_pad) + ETH_HLEN;
  
  	DPRINTK("br2684_push
  ");
  
  	if (unlikely(skb == NULL)) {
  		/* skb==NULL means VCC is being destroyed */
  		br2684_close_vcc(brvcc);
  		if (list_empty(&brdev->brvccs)) {
  			read_lock(&devs_lock);
  			list_del(&brdev->br2684_devs);
  			read_unlock(&devs_lock);
  			unregister_netdev(net_dev);
  			free_netdev(net_dev);
  		}
  		return;
  	}
  
  	skb_debug(skb);
  	atm_return(atmvcc, skb->truesize);
  	DPRINTK("skb from brdev %p
  ", brdev);
  	if (brvcc->encaps == e_llc) {
  		/* let us waste some time for checking the encapsulation.
  		   Note, that only 7 char is checked so frames with a valid FCS
  		   are also accepted (but FCS is not checked of course) */
  		if (memcmp(skb->data, llc_oui_pid_pad, 7)) {
  			brdev->stats.rx_errors++;
  			dev_kfree_skb(skb);
  			return;
  		}
  
  		/* Strip FCS if present */
  		if (skb->len > 7 && skb->data[7] == 0x01)
  			__skb_trim(skb, skb->len - 4);
  	} else {
  		plen = PADLEN + ETH_HLEN;	/* pad, dstmac,srcmac, ethtype */
  		/* first 2 chars should be 0 */
  		if (*((u16 *) (skb->data)) != 0) {
  			brdev->stats.rx_errors++;
  			dev_kfree_skb(skb);
  			return;
  		}
  	}
  	if (skb->len < plen) {
  		brdev->stats.rx_errors++;
  		dev_kfree_skb(skb);	/* dev_ not needed? */
  		return;
  	}
  
  #ifdef FASTER_VERSION
  	/* FIXME: tcpdump shows that pointer to mac header is 2 bytes earlier,
  	   than should be. What else should I set? */
  	skb_pull(skb, plen);

  	skb_set_mac_header(skb, -ETH_HLEN);

  	skb->pkt_type = PACKET_HOST;

  	skb->protocol = br_type_trans(skb, net_dev);

  #else
  	skb_pull(skb, plen - ETH_HLEN);
  	skb->protocol = eth_type_trans(skb, net_dev);
  #endif /* FASTER_VERSION */
  #ifdef CONFIG_ATM_BR2684_IPFILTER
  	if (unlikely(packet_fails_filter(skb->protocol, brvcc, skb))) {
  		brdev->stats.rx_dropped++;
  		dev_kfree_skb(skb);
  		return;
  	}
  #endif /* CONFIG_ATM_BR2684_IPFILTER */
  	skb->dev = net_dev;
  	ATM_SKB(skb)->vcc = atmvcc;	/* needed ? */
  	DPRINTK("received packet's protocol: %x
  ", ntohs(skb->protocol));
  	skb_debug(skb);
  	if (unlikely(!(net_dev->flags & IFF_UP))) {
  		/* sigh, interface is down */
  		brdev->stats.rx_dropped++;
  		dev_kfree_skb(skb);
  		return;
  	}
  	brdev->stats.rx_packets++;
  	brdev->stats.rx_bytes += skb->len;
  	memset(ATM_SKB(skb), 0, sizeof(struct atm_skb_data));
  	netif_rx(skb);
  }
  
  static int br2684_regvcc(struct atm_vcc *atmvcc, void __user *arg)
  {
  /* assign a vcc to a dev
  Note: we do not have explicit unassign, but look at _push()
  */
  	int err;
  	struct br2684_vcc *brvcc;

  	struct sk_buff *skb;

  	struct sk_buff_head *rq;

  	struct br2684_dev *brdev;
  	struct net_device *net_dev;
  	struct atm_backend_br2684 be;

  	unsigned long flags;

  
  	if (copy_from_user(&be, arg, sizeof be))
  		return -EFAULT;

  	brvcc = kzalloc(sizeof(struct br2684_vcc), GFP_KERNEL);

  	if (!brvcc)
  		return -ENOMEM;

  	write_lock_irq(&devs_lock);
  	net_dev = br2684_find_dev(&be.ifspec);
  	if (net_dev == NULL) {
  		printk(KERN_ERR
  		    "br2684: tried to attach to non-existant device
  ");
  		err = -ENXIO;
  		goto error;
  	}
  	brdev = BRPRIV(net_dev);
  	if (atmvcc->push == NULL) {
  		err = -EBADFD;
  		goto error;
  	}
  	if (!list_empty(&brdev->brvccs)) {
  		/* Only 1 VCC/dev right now */
  		err = -EEXIST;
  		goto error;
  	}
  	if (be.fcs_in != BR2684_FCSIN_NO || be.fcs_out != BR2684_FCSOUT_NO ||
  	    be.fcs_auto || be.has_vpiid || be.send_padding || (be.encaps !=
  	    BR2684_ENCAPS_VC && be.encaps != BR2684_ENCAPS_LLC) ||
  	    be.min_size != 0) {
  		err = -EINVAL;
  		goto error;
  	}
  	DPRINTK("br2684_regvcc vcc=%p, encaps=%d, brvcc=%p
  ", atmvcc, be.encaps,
  		brvcc);
  	if (list_empty(&brdev->brvccs) && !brdev->mac_was_set) {
  		unsigned char *esi = atmvcc->dev->esi;
  		if (esi[0] | esi[1] | esi[2] | esi[3] | esi[4] | esi[5])
  			memcpy(net_dev->dev_addr, esi, net_dev->addr_len);
  		else
  			net_dev->dev_addr[2] = 1;
  	}
  	list_add(&brvcc->brvccs, &brdev->brvccs);
  	write_unlock_irq(&devs_lock);
  	brvcc->device = net_dev;
  	brvcc->atmvcc = atmvcc;
  	atmvcc->user_back = brvcc;
  	brvcc->encaps = (enum br2684_encaps) be.encaps;
  	brvcc->old_push = atmvcc->push;
  	barrier();
  	atmvcc->push = br2684_push;

  
  	rq = &sk_atm(atmvcc)->sk_receive_queue;
  
  	spin_lock_irqsave(&rq->lock, flags);
  	if (skb_queue_empty(rq)) {
  		skb = NULL;
  	} else {
  		/* NULL terminate the list.  */
  		rq->prev->next = NULL;
  		skb = rq->next;
  	}
  	rq->prev = rq->next = (struct sk_buff *)rq;
  	rq->qlen = 0;
  	spin_unlock_irqrestore(&rq->lock, flags);
  
  	while (skb) {
  		struct sk_buff *next = skb->next;
  
  		skb->next = skb->prev = NULL;

  		BRPRIV(skb->dev)->stats.rx_bytes -= skb->len;
  		BRPRIV(skb->dev)->stats.rx_packets--;
  		br2684_push(atmvcc, skb);

  
  		skb = next;

  	}
  	__module_get(THIS_MODULE);
  	return 0;
      error:
  	write_unlock_irq(&devs_lock);
  	kfree(brvcc);
  	return err;
  }
  
  static void br2684_setup(struct net_device *netdev)
  {
  	struct br2684_dev *brdev = BRPRIV(netdev);
  
  	ether_setup(netdev);
  	brdev->net_dev = netdev;
  
  #ifdef FASTER_VERSION
  	my_eth_header = netdev->hard_header;
  	netdev->hard_header = br2684_header;
  	my_eth_header_cache = netdev->hard_header_cache;
  	netdev->hard_header_cache = br2684_header_cache;
  	netdev->hard_header_len = sizeof(llc_oui_pid_pad) + ETH_HLEN;	/* 10 + 14 */
  #endif
  	my_eth_mac_addr = netdev->set_mac_address;
  	netdev->set_mac_address = br2684_mac_addr;
  	netdev->hard_start_xmit = br2684_start_xmit;
  	netdev->get_stats = br2684_get_stats;
  
  	INIT_LIST_HEAD(&brdev->brvccs);
  }
  
  static int br2684_create(void __user *arg)
  {
  	int err;
  	struct net_device *netdev;
  	struct br2684_dev *brdev;
  	struct atm_newif_br2684 ni;
  
  	DPRINTK("br2684_create
  ");
  
  	if (copy_from_user(&ni, arg, sizeof ni)) {
  		return -EFAULT;
  	}
  	if (ni.media != BR2684_MEDIA_ETHERNET || ni.mtu != 1500) {
  		return -EINVAL;
  	}
  
  	netdev = alloc_netdev(sizeof(struct br2684_dev),
  			      ni.ifname[0] ? ni.ifname : "nas%d",
  			      br2684_setup);
  	if (!netdev)
  		return -ENOMEM;
  
  	brdev = BRPRIV(netdev);
  
  	DPRINTK("registered netdev %s
  ", netdev->name);
  	/* open, stop, do_ioctl ? */
  	err = register_netdev(netdev);
  	if (err < 0) {
  		printk(KERN_ERR "br2684_create: register_netdev failed
  ");
  		free_netdev(netdev);
  		return err;
  	}
  
  	write_lock_irq(&devs_lock);
  	brdev->number = list_empty(&br2684_devs) ? 1 :
  	    BRPRIV(list_entry_brdev(br2684_devs.prev))->number + 1;
  	list_add_tail(&brdev->br2684_devs, &br2684_devs);
  	write_unlock_irq(&devs_lock);
  	return 0;
  }
  
  /*
   * This handles ioctls actually performed on our vcc - we must return
   * -ENOIOCTLCMD for any unrecognized ioctl
   */
  static int br2684_ioctl(struct socket *sock, unsigned int cmd,
  	unsigned long arg)
  {
  	struct atm_vcc *atmvcc = ATM_SD(sock);
  	void __user *argp = (void __user *)arg;
  
  	int err;
  	switch(cmd) {
  	case ATM_SETBACKEND:
  	case ATM_NEWBACKENDIF: {
  		atm_backend_t b;
  		err = get_user(b, (atm_backend_t __user *) argp);
  		if (err)
  			return -EFAULT;
  		if (b != ATM_BACKEND_BR2684)
  			return -ENOIOCTLCMD;
  		if (!capable(CAP_NET_ADMIN))
  			return -EPERM;
  		if (cmd == ATM_SETBACKEND)
  			return br2684_regvcc(atmvcc, argp);
  		else
  			return br2684_create(argp);
  		}
  #ifdef CONFIG_ATM_BR2684_IPFILTER
  	case BR2684_SETFILT:
  		if (atmvcc->push != br2684_push)
  			return -ENOIOCTLCMD;
  		if (!capable(CAP_NET_ADMIN))
  			return -EPERM;
  		err = br2684_setfilt(atmvcc, argp);
  		return err;
  #endif /* CONFIG_ATM_BR2684_IPFILTER */
  	}
  	return -ENOIOCTLCMD;
  }
  
  static struct atm_ioctl br2684_ioctl_ops = {
  	.owner	= THIS_MODULE,
  	.ioctl	= br2684_ioctl,
  };
  
  
  #ifdef CONFIG_PROC_FS
  static void *br2684_seq_start(struct seq_file *seq, loff_t *pos)
  {

  	read_lock(&devs_lock);

  	return seq_list_start(&br2684_devs, *pos);

  }
  
  static void *br2684_seq_next(struct seq_file *seq, void *v, loff_t *pos)
  {

  	return seq_list_next(v, &br2684_devs, pos);

  }
  
  static void br2684_seq_stop(struct seq_file *seq, void *v)
  {
  	read_unlock(&devs_lock);
  }
  
  static int br2684_seq_show(struct seq_file *seq, void *v)
  {

  	const struct br2684_dev *brdev = list_entry(v, struct br2684_dev,
  			br2684_devs);

  	const struct net_device *net_dev = brdev->net_dev;
  	const struct br2684_vcc *brvcc;
  
  	seq_printf(seq, "dev %.16s: num=%d, mac=%02X:%02X:"
  		       "%02X:%02X:%02X:%02X (%s)
  ", net_dev->name,
  		       brdev->number,
  		       net_dev->dev_addr[0],
  		       net_dev->dev_addr[1],
  		       net_dev->dev_addr[2],
  		       net_dev->dev_addr[3],
  		       net_dev->dev_addr[4],
  		       net_dev->dev_addr[5],
  		       brdev->mac_was_set ? "set" : "auto");
  
  	list_for_each_entry(brvcc, &brdev->brvccs, brvccs) {
  		seq_printf(seq, "  vcc %d.%d.%d: encaps=%s"
  #ifndef FASTER_VERSION
  				    ", failed copies %u/%u"
  #endif /* FASTER_VERSION */
  				    "
  ", brvcc->atmvcc->dev->number,
  				    brvcc->atmvcc->vpi, brvcc->atmvcc->vci,
  				    (brvcc->encaps == e_llc) ? "LLC" : "VC"
  #ifndef FASTER_VERSION
  				    , brvcc->copies_failed
  				    , brvcc->copies_needed
  #endif /* FASTER_VERSION */
  				    );
  #ifdef CONFIG_ATM_BR2684_IPFILTER
  #define b1(var, byte)	((u8 *) &brvcc->filter.var)[byte]
  #define bs(var)		b1(var, 0), b1(var, 1), b1(var, 2), b1(var, 3)
  			if (brvcc->filter.netmask != 0)
  				seq_printf(seq, "    filter=%d.%d.%d.%d/"
  						"%d.%d.%d.%d
  ",
  						bs(prefix), bs(netmask));
  #undef bs
  #undef b1
  #endif /* CONFIG_ATM_BR2684_IPFILTER */
  	}
  	return 0;
  }

  static const struct seq_operations br2684_seq_ops = {

  	.start = br2684_seq_start,
  	.next  = br2684_seq_next,
  	.stop  = br2684_seq_stop,
  	.show  = br2684_seq_show,
  };
  
  static int br2684_proc_open(struct inode *inode, struct file *file)
  {
  	return seq_open(file, &br2684_seq_ops);
  }

  static const struct file_operations br2684_proc_ops = {

  	.owner   = THIS_MODULE,
  	.open    = br2684_proc_open,
  	.read    = seq_read,
  	.llseek  = seq_lseek,
  	.release = seq_release,
  };
  
  extern struct proc_dir_entry *atm_proc_root;	/* from proc.c */
  #endif
  
  static int __init br2684_init(void)
  {
  #ifdef CONFIG_PROC_FS
  	struct proc_dir_entry *p;
  	if ((p = create_proc_entry("br2684", 0, atm_proc_root)) == NULL)
  		return -ENOMEM;
  	p->proc_fops = &br2684_proc_ops;
  #endif
  	register_atm_ioctl(&br2684_ioctl_ops);
  	return 0;
  }
  
  static void __exit br2684_exit(void)
  {
  	struct net_device *net_dev;
  	struct br2684_dev *brdev;
  	struct br2684_vcc *brvcc;
  	deregister_atm_ioctl(&br2684_ioctl_ops);
  
  #ifdef CONFIG_PROC_FS
  	remove_proc_entry("br2684", atm_proc_root);
  #endif
  
  	while (!list_empty(&br2684_devs)) {
  		net_dev = list_entry_brdev(br2684_devs.next);
  		brdev = BRPRIV(net_dev);
  		while (!list_empty(&brdev->brvccs)) {
  			brvcc = list_entry_brvcc(brdev->brvccs.next);
  			br2684_close_vcc(brvcc);
  		}
  
  		list_del(&brdev->br2684_devs);
  		unregister_netdev(net_dev);
  		free_netdev(net_dev);
  	}
  }
  
  module_init(br2684_init);
  module_exit(br2684_exit);
  
  MODULE_AUTHOR("Marcell GAL");
  MODULE_DESCRIPTION("RFC2684 bridged protocols over ATM/AAL5");
  MODULE_LICENSE("GPL");