/*

   * Ethernet netdevice using ATM AAL5 as underlying carrier
   * (RFC1483 obsoleted by RFC2684) for Linux
   *
   * Authors: Marcell GAL, 2000, XDSL Ltd, Hungary
   *          Eric Kinzie, 2006-2007, US Naval Research Laboratory
   */

  #define pr_fmt(fmt) KBUILD_MODNAME ":%s: " fmt, __func__

  #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 <linux/uaccess.h>

  #include <linux/slab.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"

  static void skb_debug(const struct sk_buff *skb)
  {

  #ifdef SKB_DEBUG

  #define NUM2PRINT 50

  	print_hex_dump(KERN_DEBUG, "br2684: skb: ", DUMP_OFFSET,
  		       16, 1, skb->data, min(NUM2PRINT, skb->len), true);

  #endif

  }

  #define BR2684_ETHERTYPE_LEN	2
  #define BR2684_PAD_LEN		2
  
  #define LLC		0xaa, 0xaa, 0x03
  #define SNAP_BRIDGED	0x00, 0x80, 0xc2
  #define SNAP_ROUTED	0x00, 0x00, 0x00
  #define PID_ETHERNET	0x00, 0x07
  #define ETHERTYPE_IPV4	0x08, 0x00
  #define ETHERTYPE_IPV6	0x86, 0xdd
  #define PAD_BRIDGED	0x00, 0x00

  static const unsigned char ethertype_ipv4[] = { ETHERTYPE_IPV4 };
  static const unsigned char ethertype_ipv6[] = { ETHERTYPE_IPV6 };
  static const unsigned char llc_oui_pid_pad[] =

  			{ LLC, SNAP_BRIDGED, PID_ETHERNET, PAD_BRIDGED };

  static const unsigned char pad[] = { PAD_BRIDGED };

  static const unsigned char llc_oui_ipv4[] = { LLC, SNAP_ROUTED, ETHERTYPE_IPV4 };
  static const unsigned char llc_oui_ipv6[] = { LLC, SNAP_ROUTED, ETHERTYPE_IPV6 };

  
  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 */

  	unsigned copies_needed, copies_failed;

  };
  
  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) */

  	int mac_was_set;

  	enum br2684_payload payload;

  };
  
  /*
   * 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 netdev_priv(net_dev);

  }
  
  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;
  }

  static int atm_dev_event(struct notifier_block *this, unsigned long event,
  		 void *arg)
  {
  	struct atm_dev *atm_dev = arg;
  	struct list_head *lh;
  	struct net_device *net_dev;
  	struct br2684_vcc *brvcc;
  	struct atm_vcc *atm_vcc;
  	unsigned long flags;
  
  	pr_debug("event=%ld dev=%p
  ", event, atm_dev);
  
  	read_lock_irqsave(&devs_lock, flags);
  	list_for_each(lh, &br2684_devs) {
  		net_dev = list_entry_brdev(lh);
  
  		list_for_each_entry(brvcc, &BRPRIV(net_dev)->brvccs, brvccs) {
  			atm_vcc = brvcc->atmvcc;
  			if (atm_vcc && brvcc->atmvcc->dev == atm_dev) {
  
  				if (atm_vcc->dev->signal == ATM_PHY_SIG_LOST)
  					netif_carrier_off(net_dev);
  				else
  					netif_carrier_on(net_dev);
  
  			}
  		}
  	}
  	read_unlock_irqrestore(&devs_lock, flags);
  
  	return NOTIFY_DONE;
  }
  
  static struct notifier_block atm_dev_notifier = {
  	.notifier_call = atm_dev_event,
  };

  /* chained vcc->pop function.  Check if we should wake the netif_queue */
  static void br2684_pop(struct atm_vcc *vcc, struct sk_buff *skb)
  {
  	struct br2684_vcc *brvcc = BR2684_VCC(vcc);
  	struct net_device *net_dev = skb->dev;

  	pr_debug("(vcc %p ; net_dev %p )
  ", vcc, net_dev);

  	brvcc->old_pop(vcc, skb);
  
  	if (!net_dev)
  		return;
  
  	if (atm_may_send(vcc, 0))
  		netif_wake_queue(net_dev);
  
  }

  /*
   * 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 net_device *dev,

  			   struct br2684_vcc *brvcc)

  {

  	struct br2684_dev *brdev = BRPRIV(dev);

  	struct atm_vcc *atmvcc;

  	int minheadroom = (brvcc->encaps == e_llc) ?
  		((brdev->payload == p_bridged) ?
  			sizeof(llc_oui_pid_pad) : sizeof(llc_oui_ipv4)) :
  		((brdev->payload == p_bridged) ? BR2684_PAD_LEN : 0);

  	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;
  	}

  
  	if (brvcc->encaps == e_llc) {
  		if (brdev->payload == p_bridged) {
  			skb_push(skb, sizeof(llc_oui_pid_pad));

  			skb_copy_to_linear_data(skb, llc_oui_pid_pad,
  						sizeof(llc_oui_pid_pad));

  		} else if (brdev->payload == p_routed) {
  			unsigned short prot = ntohs(skb->protocol);
  
  			skb_push(skb, sizeof(llc_oui_ipv4));
  			switch (prot) {

  			case ETH_P_IP:
  				skb_copy_to_linear_data(skb, llc_oui_ipv4,
  							sizeof(llc_oui_ipv4));
  				break;
  			case ETH_P_IPV6:
  				skb_copy_to_linear_data(skb, llc_oui_ipv6,
  							sizeof(llc_oui_ipv6));
  				break;
  			default:
  				dev_kfree_skb(skb);
  				return 0;

  			}
  		}

  	} else { /* e_vc */
  		if (brdev->payload == p_bridged) {
  			skb_push(skb, 2);

  			memset(skb->data, 0, 2);

  		}

  	}

  	skb_debug(skb);
  
  	ATM_SKB(skb)->vcc = atmvcc = brvcc->atmvcc;

  	pr_debug("atm_skb(%p)->vcc(%p)->dev(%p)
  ", skb, atmvcc, atmvcc->dev);

  	atomic_add(skb->truesize, &sk_atm(atmvcc)->sk_wmem_alloc);
  	ATM_SKB(skb)->atm_options = atmvcc->atm_options;

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

  	atmvcc->send(atmvcc, skb);

  
  	if (!atm_may_send(atmvcc, 0)) {
  		netif_stop_queue(brvcc->device);
  		/*check for race with br2684_pop*/
  		if (atm_may_send(atmvcc, 0))
  			netif_start_queue(brvcc->device);
  	}

  	return 1;
  }

  static inline struct br2684_vcc *pick_outgoing_vcc(const struct sk_buff *skb,
  						   const struct br2684_dev *brdev)

  {

  	return list_empty(&brdev->brvccs) ? NULL : list_entry_brvcc(brdev->brvccs.next);	/* 1 vcc/dev right now */

  }

  static netdev_tx_t br2684_start_xmit(struct sk_buff *skb,
  				     struct net_device *dev)

  {
  	struct br2684_dev *brdev = BRPRIV(dev);
  	struct br2684_vcc *brvcc;

  	pr_debug("skb_dst(skb)=%p
  ", skb_dst(skb));

  	read_lock(&devs_lock);
  	brvcc = pick_outgoing_vcc(skb, brdev);
  	if (brvcc == NULL) {

  		pr_debug("no vcc attached to dev %s
  ", dev->name);

  		dev->stats.tx_errors++;
  		dev->stats.tx_carrier_errors++;

  		/* netif_stop_queue(dev); */
  		dev_kfree_skb(skb);
  		read_unlock(&devs_lock);

  		return NETDEV_TX_OK;

  	}

  	if (!br2684_xmit_vcc(skb, dev, 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->stats.tx_errors++;
  		dev->stats.tx_fifo_errors++;

  	}
  	read_unlock(&devs_lock);

  	return NETDEV_TX_OK;

  }

  /*
   * 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 br2684_mac_addr(struct net_device *dev, void *p)
  {

  	int err = 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)
  {

  	pr_debug("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);

  	pr_debug("
  ");

  
  	if (unlikely(skb == NULL)) {
  		/* skb==NULL means VCC is being destroyed */
  		br2684_close_vcc(brvcc);
  		if (list_empty(&brdev->brvccs)) {

  			write_lock_irq(&devs_lock);

  			list_del(&brdev->br2684_devs);

  			write_unlock_irq(&devs_lock);

  			unregister_netdev(net_dev);

  			free_netdev(net_dev);

  		}
  		return;
  	}
  
  	skb_debug(skb);
  	atm_return(atmvcc, skb->truesize);

  	pr_debug("skb from brdev %p
  ", brdev);

  	if (brvcc->encaps == e_llc) {

  
  		if (skb->len > 7 && skb->data[7] == 0x01)
  			__skb_trim(skb, skb->len - 4);
  
  		/* accept packets that have "ipv[46]" in the snap header */

  		if ((skb->len >= (sizeof(llc_oui_ipv4))) &&
  		    (memcmp(skb->data, llc_oui_ipv4,
  			    sizeof(llc_oui_ipv4) - BR2684_ETHERTYPE_LEN) == 0)) {
  			if (memcmp(skb->data + 6, ethertype_ipv6,
  				   sizeof(ethertype_ipv6)) == 0)

  				skb->protocol = htons(ETH_P_IPV6);

  			else if (memcmp(skb->data + 6, ethertype_ipv4,
  					sizeof(ethertype_ipv4)) == 0)

  				skb->protocol = htons(ETH_P_IP);

  			else
  				goto error;

  			skb_pull(skb, sizeof(llc_oui_ipv4));
  			skb_reset_network_header(skb);
  			skb->pkt_type = PACKET_HOST;

  		/*
  		 * 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).
  		 */

  		} else if ((skb->len >= sizeof(llc_oui_pid_pad)) &&

  			   (memcmp(skb->data, llc_oui_pid_pad, 7) == 0)) {

  			skb_pull(skb, sizeof(llc_oui_pid_pad));
  			skb->protocol = eth_type_trans(skb, net_dev);

  		} else
  			goto error;

  	} else { /* e_vc */
  		if (brdev->payload == p_routed) {
  			struct iphdr *iph;
  
  			skb_reset_network_header(skb);
  			iph = ip_hdr(skb);
  			if (iph->version == 4)

  				skb->protocol = htons(ETH_P_IP);

  			else if (iph->version == 6)

  				skb->protocol = htons(ETH_P_IPV6);

  			else
  				goto error;
  			skb->pkt_type = PACKET_HOST;
  		} else { /* p_bridged */
  			/* first 2 chars should be 0 */

  			if (memcmp(skb->data, pad, BR2684_PAD_LEN) != 0)

  				goto error;
  			skb_pull(skb, BR2684_PAD_LEN);
  			skb->protocol = eth_type_trans(skb, net_dev);

  		}

  	}

  #ifdef CONFIG_ATM_BR2684_IPFILTER

  	if (unlikely(packet_fails_filter(skb->protocol, brvcc, skb)))
  		goto dropped;

  #endif /* CONFIG_ATM_BR2684_IPFILTER */
  	skb->dev = net_dev;
  	ATM_SKB(skb)->vcc = atmvcc;	/* needed ? */

  	pr_debug("received packet's protocol: %x
  ", ntohs(skb->protocol));

  	skb_debug(skb);

  	/* sigh, interface is down? */
  	if (unlikely(!(net_dev->flags & IFF_UP)))
  		goto dropped;

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

  	memset(ATM_SKB(skb), 0, sizeof(struct atm_skb_data));
  	netif_rx(skb);

  	return;
  
  dropped:

  	net_dev->stats.rx_dropped++;

  	goto free_skb;
  error:

  	net_dev->stats.rx_errors++;

  free_skb:
  	dev_kfree_skb(skb);

  }

  /*
   * Assign a vcc to a dev
   * Note: we do not have explicit unassign, but look at _push()
   */
  static int br2684_regvcc(struct atm_vcc *atmvcc, void __user * arg)

  {

  	struct br2684_vcc *brvcc;

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

  	int err;

  
  	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) {

  		pr_err("tried to attach to non-existent 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;
  	}

  	pr_debug("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;

  	brvcc->old_pop = atmvcc->pop;

  	barrier();
  	atmvcc->push = br2684_push;

  	atmvcc->pop = br2684_pop;

  	/* initialize netdev carrier state */
  	if (atmvcc->dev->signal == ATM_PHY_SIG_LOST)
  		netif_carrier_off(net_dev);
  	else
  		netif_carrier_on(net_dev);

  	__module_get(THIS_MODULE);

  
  	/* re-process everything received between connection setup and
  	   backend setup */
  	vcc_process_recv_queue(atmvcc);

  	return 0;

  
  error:

  	write_unlock_irq(&devs_lock);
  	kfree(brvcc);
  	return err;
  }

  static const struct net_device_ops br2684_netdev_ops = {
  	.ndo_start_xmit 	= br2684_start_xmit,
  	.ndo_set_mac_address	= br2684_mac_addr,
  	.ndo_change_mtu		= eth_change_mtu,
  	.ndo_validate_addr	= eth_validate_addr,
  };

  static const struct net_device_ops br2684_netdev_ops_routed = {
  	.ndo_start_xmit 	= br2684_start_xmit,
  	.ndo_set_mac_address	= br2684_mac_addr,
  	.ndo_change_mtu		= eth_change_mtu
  };

  static void br2684_setup(struct net_device *netdev)
  {
  	struct br2684_dev *brdev = BRPRIV(netdev);
  
  	ether_setup(netdev);

  	netdev->hard_header_len += sizeof(llc_oui_pid_pad); /* worst case */

  	brdev->net_dev = netdev;

  	netdev->netdev_ops = &br2684_netdev_ops;

  
  	INIT_LIST_HEAD(&brdev->brvccs);
  }

  static void br2684_setup_routed(struct net_device *netdev)
  {
  	struct br2684_dev *brdev = BRPRIV(netdev);

  	brdev->net_dev = netdev;

  	netdev->hard_header_len = sizeof(llc_oui_ipv4); /* worst case */

  	netdev->netdev_ops = &br2684_netdev_ops_routed;

  	netdev->addr_len = 0;
  	netdev->mtu = 1500;
  	netdev->type = ARPHRD_PPP;
  	netdev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
  	netdev->tx_queue_len = 100;
  	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;

  	enum br2684_payload payload;

  	pr_debug("
  ");

  	if (copy_from_user(&ni, arg, sizeof ni))

  		return -EFAULT;

  
  	if (ni.media & BR2684_FLAG_ROUTED)
  		payload = p_routed;
  	else
  		payload = p_bridged;

  	ni.media &= 0xffff;	/* strip flags */

  	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",

  			      (payload == p_routed) ?

  			      br2684_setup_routed : br2684_setup);

  	if (!netdev)
  		return -ENOMEM;
  
  	brdev = BRPRIV(netdev);

  	pr_debug("registered netdev %s
  ", netdev->name);

  	/* open, stop, do_ioctl ? */
  	err = register_netdev(netdev);
  	if (err < 0) {

  		pr_err("register_netdev failed
  ");

  		free_netdev(netdev);
  		return err;
  	}
  
  	write_lock_irq(&devs_lock);

  	brdev->payload = payload;

  
  	if (list_empty(&br2684_devs)) {
  		/* 1st br2684 device */

  		brdev->number = 1;
  	} else
  		brdev->number = 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;

  	atm_backend_t b;

  
  	int err;

  	switch (cmd) {

  	case ATM_SETBACKEND:

  	case ATM_NEWBACKENDIF:

  		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)

  	__acquires(devs_lock)

  {

  	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)

  	__releases(devs_lock)

  {
  	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=%pM (%s)
  ",

  		   net_dev->name,
  		   brdev->number,

  		   net_dev->dev_addr,

  		   brdev->mac_was_set ? "set" : "auto");

  
  	list_for_each_entry(brvcc, &brdev->brvccs, brvccs) {

  		seq_printf(seq, "  vcc %d.%d.%d: encaps=%s payload=%s"

  			   ", failed copies %u/%u"
  			   "
  ", brvcc->atmvcc->dev->number,
  			   brvcc->atmvcc->vpi, brvcc->atmvcc->vci,
  			   (brvcc->encaps == e_llc) ? "LLC" : "VC",
  			   (brdev->payload == p_bridged) ? "bridged" : "routed",
  			   brvcc->copies_failed, brvcc->copies_needed);

  #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 /* CONFIG_PROC_FS */

  
  static int __init br2684_init(void)
  {
  #ifdef CONFIG_PROC_FS
  	struct proc_dir_entry *p;

  	p = proc_create("br2684", 0, atm_proc_root, &br2684_proc_ops);
  	if (p == NULL)

  		return -ENOMEM;

  #endif
  	register_atm_ioctl(&br2684_ioctl_ops);

  	register_atmdevice_notifier(&atm_dev_notifier);

  	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

  	unregister_atmdevice_notifier(&atm_dev_notifier);

  	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");