text: /*
     Copyright (c) 2013-2014 Intel Corp.
  
     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License version 2 and
     only version 2 as published by the Free Software Foundation.
  
     This program is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     GNU General Public License for more details.
  */
  
  #include <linux/if_arp.h>
  #include <linux/netdevice.h>
  #include <linux/etherdevice.h>
  #include <linux/module.h>
  #include <linux/debugfs.h>
  
  #include <net/ipv6.h>
  #include <net/ip6_route.h>
  #include <net/addrconf.h>
  
  #include <net/bluetooth/bluetooth.h>
  #include <net/bluetooth/hci_core.h>
  #include <net/bluetooth/l2cap.h>
  
  #include <net/6lowpan.h> /* for the compression support */
  
  #define VERSION "0.1"
  
  static struct dentry *lowpan_enable_debugfs;
  static struct dentry *lowpan_control_debugfs;
  
  #define IFACE_NAME_TEMPLATE "bt%d"
  
  struct skb_cb {
  	struct in6_addr addr;
  	struct in6_addr gw;
  	struct l2cap_chan *chan;
  	int status;
  };
  #define lowpan_cb(skb) ((struct skb_cb *)((skb)->cb))
  
  /* The devices list contains those devices that we are acting
   * as a proxy. The BT 6LoWPAN device is a virtual device that
   * connects to the Bluetooth LE device. The real connection to
   * BT device is done via l2cap layer. There exists one
   * virtual device / one BT 6LoWPAN network (=hciX device).
   * The list contains struct lowpan_dev elements.
   */
  static LIST_HEAD(bt_6lowpan_devices);
  static DEFINE_SPINLOCK(devices_lock);
  
  static bool enable_6lowpan;
  
  /* We are listening incoming connections via this channel
   */
  static struct l2cap_chan *listen_chan;
  
  struct lowpan_peer {
  	struct list_head list;
  	struct rcu_head rcu;
  	struct l2cap_chan *chan;
  
  	/* peer addresses in various formats */
  	unsigned char eui64_addr[EUI64_ADDR_LEN];
  	struct in6_addr peer_addr;
  };
  
  struct lowpan_btle_dev {
  	struct list_head list;
  
  	struct hci_dev *hdev;
  	struct net_device *netdev;
  	struct list_head peers;
  	atomic_t peer_count; /* number of items in peers list */
  
  	struct work_struct delete_netdev;
  	struct delayed_work notify_peers;
  };
  
  static inline struct lowpan_btle_dev *
  lowpan_btle_dev(const struct net_device *netdev)
  {
  	return (struct lowpan_btle_dev *)lowpan_dev(netdev)->priv;
  }
  
  static inline void peer_add(struct lowpan_btle_dev *dev,
  			    struct lowpan_peer *peer)
  {
  	list_add_rcu(&peer->list, &dev->peers);
  	atomic_inc(&dev->peer_count);
  }
  
  static inline bool peer_del(struct lowpan_btle_dev *dev,
  			    struct lowpan_peer *peer)
  {
  	list_del_rcu(&peer->list);
  	kfree_rcu(peer, rcu);
  
  	module_put(THIS_MODULE);
  
  	if (atomic_dec_and_test(&dev->peer_count)) {
  		BT_DBG("last peer");
  		return true;
  	}
  
  	return false;
  }
  
  static inline struct lowpan_peer *peer_lookup_ba(struct lowpan_btle_dev *dev,
  						 bdaddr_t *ba, __u8 type)
  {
  	struct lowpan_peer *peer;
  
  	BT_DBG("peers %d addr %pMR type %d", atomic_read(&dev->peer_count),
  	       ba, type);
  
  	rcu_read_lock();
  
  	list_for_each_entry_rcu(peer, &dev->peers, list) {
  		BT_DBG("dst addr %pMR dst type %d",
  		       &peer->chan->dst, peer->chan->dst_type);
  
  		if (bacmp(&peer->chan->dst, ba))
  			continue;
  
  		if (type == peer->chan->dst_type) {
  			rcu_read_unlock();
  			return peer;
  		}
  	}
  
  	rcu_read_unlock();
  
  	return NULL;
  }
  
  static inline struct lowpan_peer *
  __peer_lookup_chan(struct lowpan_btle_dev *dev, struct l2cap_chan *chan)
  {
  	struct lowpan_peer *peer;
  
  	list_for_each_entry_rcu(peer, &dev->peers, list) {
  		if (peer->chan == chan)
  			return peer;
  	}
  
  	return NULL;
  }
  
  static inline struct lowpan_peer *
  __peer_lookup_conn(struct lowpan_btle_dev *dev, struct l2cap_conn *conn)
  {
  	struct lowpan_peer *peer;
  
  	list_for_each_entry_rcu(peer, &dev->peers, list) {
  		if (peer->chan->conn == conn)
  			return peer;
  	}
  
  	return NULL;
  }
  
  static inline struct lowpan_peer *peer_lookup_dst(struct lowpan_btle_dev *dev,
  						  struct in6_addr *daddr,
  						  struct sk_buff *skb)
  {
  	struct lowpan_peer *peer;
  	struct in6_addr *nexthop;
  	struct rt6_info *rt = (struct rt6_info *)skb_dst(skb);
  	int count = atomic_read(&dev->peer_count);
  
  	BT_DBG("peers %d addr %pI6c rt %p", count, daddr, rt);
  
  	/* If we have multiple 6lowpan peers, then check where we should
  	 * send the packet. If only one peer exists, then we can send the
  	 * packet right away.
  	 */
  	if (count == 1) {
  		rcu_read_lock();
  		peer = list_first_or_null_rcu(&dev->peers, struct lowpan_peer,
  					      list);
  		rcu_read_unlock();
  		return peer;
  	}
  
  	if (!rt) {
  		nexthop = &lowpan_cb(skb)->gw;
  
  		if (ipv6_addr_any(nexthop))
  			return NULL;
  	} else {
  		nexthop = rt6_nexthop(rt, daddr);
  
  		/* We need to remember the address because it is needed
  		 * by bt_xmit() when sending the packet. In bt_xmit(), the
  		 * destination routing info is not set.
  		 */
  		memcpy(&lowpan_cb(skb)->gw, nexthop, sizeof(struct in6_addr));
  	}
  
  	BT_DBG("gw %pI6c", nexthop);
  
  	rcu_read_lock();
  
  	list_for_each_entry_rcu(peer, &dev->peers, list) {
  		BT_DBG("dst addr %pMR dst type %d ip %pI6c",
  		       &peer->chan->dst, peer->chan->dst_type,
  		       &peer->peer_addr);
  
  		if (!ipv6_addr_cmp(&peer->peer_addr, nexthop)) {
  			rcu_read_unlock();
  			return peer;
  		}
  	}
  
  	rcu_read_unlock();
  
  	return NULL;
  }
  
  static struct lowpan_peer *lookup_peer(struct l2cap_conn *conn)
  {
  	struct lowpan_btle_dev *entry;
  	struct lowpan_peer *peer = NULL;
  
  	rcu_read_lock();
  
  	list_for_each_entry_rcu(entry, &bt_6lowpan_devices, list) {
  		peer = __peer_lookup_conn(entry, conn);
  		if (peer)
  			break;
  	}
  
  	rcu_read_unlock();
  
  	return peer;
  }
  
  static struct lowpan_btle_dev *lookup_dev(struct l2cap_conn *conn)
  {
  	struct lowpan_btle_dev *entry;
  	struct lowpan_btle_dev *dev = NULL;
  
  	rcu_read_lock();
  
  	list_for_each_entry_rcu(entry, &bt_6lowpan_devices, list) {
  		if (conn->hcon->hdev == entry->hdev) {
  			dev = entry;
  			break;
  		}
  	}
  
  	rcu_read_unlock();
  
  	return dev;
  }
  
  static int give_skb_to_upper(struct sk_buff *skb, struct net_device *dev)
  {
  	struct sk_buff *skb_cp;
  
  	skb_cp = skb_copy(skb, GFP_ATOMIC);
  	if (!skb_cp)
  		return NET_RX_DROP;
  
  	return netif_rx_ni(skb_cp);
  }
  
  static int iphc_decompress(struct sk_buff *skb, struct net_device *netdev,
  			   struct l2cap_chan *chan)
  {
  	const u8 *saddr, *daddr;
  	struct lowpan_btle_dev *dev;
  	struct lowpan_peer *peer;
  
  	dev = lowpan_btle_dev(netdev);
  
  	rcu_read_lock();
  	peer = __peer_lookup_chan(dev, chan);
  	rcu_read_unlock();
  	if (!peer)
  		return -EINVAL;
  
  	saddr = peer->eui64_addr;
  	daddr = dev->netdev->dev_addr;
  
  	return lowpan_header_decompress(skb, netdev, daddr, saddr);
  }
  
  static int recv_pkt(struct sk_buff *skb, struct net_device *dev,
  		    struct l2cap_chan *chan)
  {
  	struct sk_buff *local_skb;
  	int ret;
  
  	if (!netif_running(dev))
  		goto drop;
  
  	if (dev->type != ARPHRD_6LOWPAN || !skb->len)
  		goto drop;
  
  	skb_reset_network_header(skb);
  
  	skb = skb_share_check(skb, GFP_ATOMIC);
  	if (!skb)
  		goto drop;
  
  	/* check that it's our buffer */
  	if (lowpan_is_ipv6(*skb_network_header(skb))) {
  		/* Pull off the 1-byte of 6lowpan header. */
  		skb_pull(skb, 1);
  
  		/* Copy the packet so that the IPv6 header is
  		 * properly aligned.
  		 */
  		local_skb = skb_copy_expand(skb, NET_SKB_PAD - 1,
  					    skb_tailroom(skb), GFP_ATOMIC);
  		if (!local_skb)
  			goto drop;
  
  		local_skb->protocol = htons(ETH_P_IPV6);
  		local_skb->pkt_type = PACKET_HOST;
  		local_skb->dev = dev;
  
  		skb_set_transport_header(local_skb, sizeof(struct ipv6hdr));
  
  		if (give_skb_to_upper(local_skb, dev) != NET_RX_SUCCESS) {
  			kfree_skb(local_skb);
  			goto drop;
  		}
  
  		dev->stats.rx_bytes += skb->len;
  		dev->stats.rx_packets++;
  
  		consume_skb(local_skb);
  		consume_skb(skb);
  	} else if (lowpan_is_iphc(*skb_network_header(skb))) {
  		local_skb = skb_clone(skb, GFP_ATOMIC);
  		if (!local_skb)
  			goto drop;
  
  		local_skb->dev = dev;
  
  		ret = iphc_decompress(local_skb, dev, chan);
  		if (ret < 0) {
  			kfree_skb(local_skb);
  			goto drop;
  		}
  
  		local_skb->protocol = htons(ETH_P_IPV6);
  		local_skb->pkt_type = PACKET_HOST;
  
  		if (give_skb_to_upper(local_skb, dev)
  				!= NET_RX_SUCCESS) {
  			kfree_skb(local_skb);
  			goto drop;
  		}
  
  		dev->stats.rx_bytes += skb->len;
  		dev->stats.rx_packets++;
  
  		consume_skb(local_skb);
  		consume_skb(skb);
  	} else {
  		goto drop;
  	}
  
  	return NET_RX_SUCCESS;
  
  drop:
  	dev->stats.rx_dropped++;
  	return NET_RX_DROP;
  }
  
  /* Packet from BT LE device */
  static int chan_recv_cb(struct l2cap_chan *chan, struct sk_buff *skb)
  {
  	struct lowpan_btle_dev *dev;
  	struct lowpan_peer *peer;
  	int err;
  
  	peer = lookup_peer(chan->conn);
  	if (!peer)
  		return -ENOENT;
  
  	dev = lookup_dev(chan->conn);
  	if (!dev || !dev->netdev)
  		return -ENOENT;
  
  	err = recv_pkt(skb, dev->netdev, chan);
  	if (err) {
  		BT_DBG("recv pkt %d", err);
  		err = -EAGAIN;
  	}
  
  	return err;
  }
  
  static u8 get_addr_type_from_eui64(u8 byte)
  {
  	/* Is universal(0) or local(1) bit */
  	return ((byte & 0x02) ? BDADDR_LE_RANDOM : BDADDR_LE_PUBLIC);
  }
  
  static void copy_to_bdaddr(struct in6_addr *ip6_daddr, bdaddr_t *addr)
  {
  	u8 *eui64 = ip6_daddr->s6_addr + 8;
  
  	addr->b[0] = eui64[7];
  	addr->b[1] = eui64[6];
  	addr->b[2] = eui64[5];
  	addr->b[3] = eui64[2];
  	addr->b[4] = eui64[1];
  	addr->b[5] = eui64[0];
  }
  
  static void convert_dest_bdaddr(struct in6_addr *ip6_daddr,
  				bdaddr_t *addr, u8 *addr_type)
  {
  	copy_to_bdaddr(ip6_daddr, addr);
  
  	/* We need to toggle the U/L bit that we got from IPv6 address
  	 * so that we get the proper address and type of the BD address.
  	 */
  	addr->b[5] ^= 0x02;
  
  	*addr_type = get_addr_type_from_eui64(addr->b[5]);
  }
  
  static int setup_header(struct sk_buff *skb, struct net_device *netdev,
  			bdaddr_t *peer_addr, u8 *peer_addr_type)
  {
  	struct in6_addr ipv6_daddr;
  	struct ipv6hdr *hdr;
  	struct lowpan_btle_dev *dev;
  	struct lowpan_peer *peer;
  	bdaddr_t addr, *any = BDADDR_ANY;
  	u8 *daddr = any->b;
  	int err, status = 0;
  
  	hdr = ipv6_hdr(skb);
  
  	dev = lowpan_btle_dev(netdev);
  
  	memcpy(&ipv6_daddr, &hdr->daddr, sizeof(ipv6_daddr));
  
  	if (ipv6_addr_is_multicast(&ipv6_daddr)) {
  		lowpan_cb(skb)->chan = NULL;
  	} else {
  		u8 addr_type;
  
  		/* Get destination BT device from skb.
  		 * If there is no such peer then discard the packet.
  		 */
  		convert_dest_bdaddr(&ipv6_daddr, &addr, &addr_type);
  
  		BT_DBG("dest addr %pMR type %d IP %pI6c", &addr,
  		       addr_type, &ipv6_daddr);
  
  		peer = peer_lookup_ba(dev, &addr, addr_type);
  		if (!peer) {
  			/* The packet might be sent to 6lowpan interface
  			 * because of routing (either via default route
  			 * or user set route) so get peer according to
  			 * the destination address.
  			 */
  			peer = peer_lookup_dst(dev, &ipv6_daddr, skb);
  			if (!peer) {
  				BT_DBG("no such peer %pMR found", &addr);
  				return -ENOENT;
  			}
  		}
  
  		daddr = peer->eui64_addr;
  		*peer_addr = addr;
  		*peer_addr_type = addr_type;
  		lowpan_cb(skb)->chan = peer->chan;
  
  		status = 1;
  	}
  
  	lowpan_header_compress(skb, netdev, daddr, dev->netdev->dev_addr);
  
  	err = dev_hard_header(skb, netdev, ETH_P_IPV6, NULL, NULL, 0);
  	if (err < 0)
  		return err;
  
  	return status;
  }
  
  static int header_create(struct sk_buff *skb, struct net_device *netdev,
  			 unsigned short type, const void *_daddr,
  			 const void *_saddr, unsigned int len)
  {
  	if (type != ETH_P_IPV6)
  		return -EINVAL;
  
  	return 0;
  }
  
  /* Packet to BT LE device */
  static int send_pkt(struct l2cap_chan *chan, struct sk_buff *skb,
  		    struct net_device *netdev)
  {
  	struct msghdr msg;
  	struct kvec iv;
  	int err;
  
  	/* Remember the skb so that we can send EAGAIN to the caller if
  	 * we run out of credits.
  	 */
  	chan->data = skb;
  
  	iv.iov_base = skb->data;
  	iv.iov_len = skb->len;
  
  	memset(&msg, 0, sizeof(msg));
  	iov_iter_kvec(&msg.msg_iter, WRITE | ITER_KVEC, &iv, 1, skb->len);
  
  	err = l2cap_chan_send(chan, &msg, skb->len);
  	if (err > 0) {
  		netdev->stats.tx_bytes += err;
  		netdev->stats.tx_packets++;
  		return 0;
  	}
  
  	if (!err)
  		err = lowpan_cb(skb)->status;
  
  	if (err < 0) {
  		if (err == -EAGAIN)
  			netdev->stats.tx_dropped++;
  		else
  			netdev->stats.tx_errors++;
  	}
  
  	return err;
  }
  
  static int send_mcast_pkt(struct sk_buff *skb, struct net_device *netdev)
  {
  	struct sk_buff *local_skb;
  	struct lowpan_btle_dev *entry;
  	int err = 0;
  
  	rcu_read_lock();
  
  	list_for_each_entry_rcu(entry, &bt_6lowpan_devices, list) {
  		struct lowpan_peer *pentry;
  		struct lowpan_btle_dev *dev;
  
  		if (entry->netdev != netdev)
  			continue;
  
  		dev = lowpan_btle_dev(entry->netdev);
  
  		list_for_each_entry_rcu(pentry, &dev->peers, list) {
  			int ret;
  
  			local_skb = skb_clone(skb, GFP_ATOMIC);
  
  			BT_DBG("xmit %s to %pMR type %d IP %pI6c chan %p",
  			       netdev->name,
  			       &pentry->chan->dst, pentry->chan->dst_type,
  			       &pentry->peer_addr, pentry->chan);
  			ret = send_pkt(pentry->chan, local_skb, netdev);
  			if (ret < 0)
  				err = ret;
  
  			kfree_skb(local_skb);
  		}
  	}
  
  	rcu_read_unlock();
  
  	return err;
  }
  
  static netdev_tx_t bt_xmit(struct sk_buff *skb, struct net_device *netdev)
  {
  	int err = 0;
  	bdaddr_t addr;
  	u8 addr_type;
  
  	/* We must take a copy of the skb before we modify/replace the ipv6
  	 * header as the header could be used elsewhere
  	 */
  	skb = skb_unshare(skb, GFP_ATOMIC);
  	if (!skb)
  		return NET_XMIT_DROP;
  
  	/* Return values from setup_header()
  	 *  <0 - error, packet is dropped
  	 *   0 - this is a multicast packet
  	 *   1 - this is unicast packet
  	 */
  	err = setup_header(skb, netdev, &addr, &addr_type);
  	if (err < 0) {
  		kfree_skb(skb);
  		return NET_XMIT_DROP;
  	}
  
  	if (err) {
  		if (lowpan_cb(skb)->chan) {
  			BT_DBG("xmit %s to %pMR type %d IP %pI6c chan %p",
  			       netdev->name, &addr, addr_type,
  			       &lowpan_cb(skb)->addr, lowpan_cb(skb)->chan);
  			err = send_pkt(lowpan_cb(skb)->chan, skb, netdev);
  		} else {
  			err = -ENOENT;
  		}
  	} else {
  		/* We need to send the packet to every device behind this
  		 * interface.
  		 */
  		err = send_mcast_pkt(skb, netdev);
  	}
  
  	dev_kfree_skb(skb);
  
  	if (err)
  		BT_DBG("ERROR: xmit failed (%d)", err);
  
  	return err < 0 ? NET_XMIT_DROP : err;
  }
  
  static struct lock_class_key bt_tx_busylock;
  static struct lock_class_key bt_netdev_xmit_lock_key;
  
  static void bt_set_lockdep_class_one(struct net_device *dev,
  				     struct netdev_queue *txq,
  				     void *_unused)
  {
  	lockdep_set_class(&txq->_xmit_lock, &bt_netdev_xmit_lock_key);
  }
  
  static int bt_dev_init(struct net_device *dev)
  {
  	netdev_for_each_tx_queue(dev, bt_set_lockdep_class_one, NULL);
  	dev->qdisc_tx_busylock = &bt_tx_busylock;
  
  	return 0;
  }
  
  static const struct net_device_ops netdev_ops = {
  	.ndo_init		= bt_dev_init,
  	.ndo_start_xmit		= bt_xmit,
  };
  
  static struct header_ops header_ops = {
  	.create	= header_create,
  };
  
  static void netdev_setup(struct net_device *dev)
  {
  	dev->hard_header_len	= 0;
  	dev->needed_tailroom	= 0;
  	dev->flags		= IFF_RUNNING | IFF_POINTOPOINT |
  				  IFF_MULTICAST;
  	dev->watchdog_timeo	= 0;
  
  	dev->netdev_ops		= &netdev_ops;
  	dev->header_ops		= &header_ops;
  	dev->destructor		= free_netdev;
  }
  
  static struct device_type bt_type = {
  	.name	= "bluetooth",
  };
  
  static void set_addr(u8 *eui, u8 *addr, u8 addr_type)
  {
  	/* addr is the BT address in little-endian format */
  	eui[0] = addr[5];
  	eui[1] = addr[4];
  	eui[2] = addr[3];
  	eui[3] = 0xFF;
  	eui[4] = 0xFE;
  	eui[5] = addr[2];
  	eui[6] = addr[1];
  	eui[7] = addr[0];
  
  	/* Universal/local bit set, BT 6lowpan draft ch. 3.2.1 */
  	if (addr_type == BDADDR_LE_PUBLIC)
  		eui[0] &= ~0x02;
  	else
  		eui[0] |= 0x02;
  
  	BT_DBG("type %d addr %*phC", addr_type, 8, eui);
  }
  
  static void set_dev_addr(struct net_device *netdev, bdaddr_t *addr,
  		         u8 addr_type)
  {
  	netdev->addr_assign_type = NET_ADDR_PERM;
  	set_addr(netdev->dev_addr, addr->b, addr_type);
  }
  
  static void ifup(struct net_device *netdev)
  {
  	int err;
  
  	rtnl_lock();
  	err = dev_open(netdev);
  	if (err < 0)
  		BT_INFO("iface %s cannot be opened (%d)", netdev->name, err);
  	rtnl_unlock();
  }
  
  static void ifdown(struct net_device *netdev)
  {
  	int err;
  
  	rtnl_lock();
  	err = dev_close(netdev);
  	if (err < 0)
  		BT_INFO("iface %s cannot be closed (%d)", netdev->name, err);
  	rtnl_unlock();
  }
  
  static void do_notify_peers(struct work_struct *work)
  {
  	struct lowpan_btle_dev *dev = container_of(work, struct lowpan_btle_dev,
  						   notify_peers.work);
  
  	netdev_notify_peers(dev->netdev); /* send neighbour adv at startup */
  }
  
  static bool is_bt_6lowpan(struct hci_conn *hcon)
  {
  	if (hcon->type != LE_LINK)
  		return false;
  
  	if (!enable_6lowpan)
  		return false;
  
  	return true;
  }
  
  static struct l2cap_chan *chan_create(void)
  {
  	struct l2cap_chan *chan;
  
  	chan = l2cap_chan_create();
  	if (!chan)
  		return NULL;
  
  	l2cap_chan_set_defaults(chan);
  
  	chan->chan_type = L2CAP_CHAN_CONN_ORIENTED;
  	chan->mode = L2CAP_MODE_LE_FLOWCTL;
  	chan->imtu = 1280;
  
  	return chan;
  }
  
  static void set_ip_addr_bits(u8 addr_type, u8 *addr)
  {
  	if (addr_type == BDADDR_LE_PUBLIC)
  		*addr |= 0x02;
  	else
  		*addr &= ~0x02;
  }
  
  static struct l2cap_chan *add_peer_chan(struct l2cap_chan *chan,
  					struct lowpan_btle_dev *dev)
  {
  	struct lowpan_peer *peer;
  
  	peer = kzalloc(sizeof(*peer), GFP_ATOMIC);
  	if (!peer)
  		return NULL;
  
  	peer->chan = chan;
  	memset(&peer->peer_addr, 0, sizeof(struct in6_addr));
  
  	/* RFC 2464 ch. 5 */
  	peer->peer_addr.s6_addr[0] = 0xFE;
  	peer->peer_addr.s6_addr[1] = 0x80;
  	set_addr((u8 *)&peer->peer_addr.s6_addr + 8, chan->dst.b,
  		 chan->dst_type);
  
  	memcpy(&peer->eui64_addr, (u8 *)&peer->peer_addr.s6_addr + 8,
  	       EUI64_ADDR_LEN);
  
  	/* IPv6 address needs to have the U/L bit set properly so toggle
  	 * it back here.
  	 */
  	set_ip_addr_bits(chan->dst_type, (u8 *)&peer->peer_addr.s6_addr + 8);
  
  	spin_lock(&devices_lock);
  	INIT_LIST_HEAD(&peer->list);
  	peer_add(dev, peer);
  	spin_unlock(&devices_lock);
  
  	/* Notifying peers about us needs to be done without locks held */
  	INIT_DELAYED_WORK(&dev->notify_peers, do_notify_peers);
  	schedule_delayed_work(&dev->notify_peers, msecs_to_jiffies(100));
  
  	return peer->chan;
  }
  
  static int setup_netdev(struct l2cap_chan *chan, struct lowpan_btle_dev **dev)
  {
  	struct net_device *netdev;
  	int err = 0;
  
  	netdev = alloc_netdev(LOWPAN_PRIV_SIZE(sizeof(struct lowpan_btle_dev)),
  			      IFACE_NAME_TEMPLATE, NET_NAME_UNKNOWN,
  			      netdev_setup);
  	if (!netdev)
  		return -ENOMEM;
  
  	set_dev_addr(netdev, &chan->src, chan->src_type);
  
  	netdev->netdev_ops = &netdev_ops;
  	SET_NETDEV_DEV(netdev, &chan->conn->hcon->hdev->dev);
  	SET_NETDEV_DEVTYPE(netdev, &bt_type);
  
  	*dev = lowpan_btle_dev(netdev);
  	(*dev)->netdev = netdev;
  	(*dev)->hdev = chan->conn->hcon->hdev;
  	INIT_LIST_HEAD(&(*dev)->peers);
  
  	spin_lock(&devices_lock);
  	INIT_LIST_HEAD(&(*dev)->list);
  	list_add_rcu(&(*dev)->list, &bt_6lowpan_devices);
  	spin_unlock(&devices_lock);
  
  	err = lowpan_register_netdev(netdev, LOWPAN_LLTYPE_BTLE);
  	if (err < 0) {
  		BT_INFO("register_netdev failed %d", err);
  		spin_lock(&devices_lock);
  		list_del_rcu(&(*dev)->list);
  		spin_unlock(&devices_lock);
  		free_netdev(netdev);
  		goto out;
  	}
  
  	BT_DBG("ifindex %d peer bdaddr %pMR type %d my addr %pMR type %d",
  	       netdev->ifindex, &chan->dst, chan->dst_type,
  	       &chan->src, chan->src_type);
  	set_bit(__LINK_STATE_PRESENT, &netdev->state);
  
  	return 0;
  
  out:
  	return err;
  }
  
  static inline void chan_ready_cb(struct l2cap_chan *chan)
  {
  	struct lowpan_btle_dev *dev;
  
  	dev = lookup_dev(chan->conn);
  
  	BT_DBG("chan %p conn %p dev %p", chan, chan->conn, dev);
  
  	if (!dev) {
  		if (setup_netdev(chan, &dev) < 0) {
  			l2cap_chan_del(chan, -ENOENT);
  			return;
  		}
  	}
  
  	if (!try_module_get(THIS_MODULE))
  		return;
  
  	add_peer_chan(chan, dev);
  	ifup(dev->netdev);
  }
  
  static inline struct l2cap_chan *chan_new_conn_cb(struct l2cap_chan *pchan)
  {
  	struct l2cap_chan *chan;
  
  	chan = chan_create();
  	if (!chan)
  		return NULL;
  
  	chan->ops = pchan->ops;
  
  	BT_DBG("chan %p pchan %p", chan, pchan);
  
  	return chan;
  }
  
  static void delete_netdev(struct work_struct *work)
  {
  	struct lowpan_btle_dev *entry = container_of(work,
  						     struct lowpan_btle_dev,
  						     delete_netdev);
  
  	lowpan_unregister_netdev(entry->netdev);
  
  	/* The entry pointer is deleted by the netdev destructor. */
  }
  
  static void chan_close_cb(struct l2cap_chan *chan)
  {
  	struct lowpan_btle_dev *entry;
  	struct lowpan_btle_dev *dev = NULL;
  	struct lowpan_peer *peer;
  	int err = -ENOENT;
  	bool last = false, remove = true;
  
  	BT_DBG("chan %p conn %p", chan, chan->conn);
  
  	if (chan->conn && chan->conn->hcon) {
  		if (!is_bt_6lowpan(chan->conn->hcon))
  			return;
  
  		/* If conn is set, then the netdev is also there and we should
  		 * not remove it.
  		 */
  		remove = false;
  	}
  
  	spin_lock(&devices_lock);
  
  	list_for_each_entry_rcu(entry, &bt_6lowpan_devices, list) {
  		dev = lowpan_btle_dev(entry->netdev);
  		peer = __peer_lookup_chan(dev, chan);
  		if (peer) {
  			last = peer_del(dev, peer);
  			err = 0;
  
  			BT_DBG("dev %p removing %speer %p", dev,
  			       last ? "last " : "1 ", peer);
  			BT_DBG("chan %p orig refcnt %d", chan,
  			       atomic_read(&chan->kref.refcount));
  
  			l2cap_chan_put(chan);
  			break;
  		}
  	}
  
  	if (!err && last && dev && !atomic_read(&dev->peer_count)) {
  		spin_unlock(&devices_lock);
  
  		cancel_delayed_work_sync(&dev->notify_peers);
  
  		ifdown(dev->netdev);
  
  		if (remove) {
  			INIT_WORK(&entry->delete_netdev, delete_netdev);
  			schedule_work(&entry->delete_netdev);
  		}
  	} else {
  		spin_unlock(&devices_lock);
  	}
  
  	return;
  }
  
  static void chan_state_change_cb(struct l2cap_chan *chan, int state, int err)
  {
  	BT_DBG("chan %p conn %p state %s err %d", chan, chan->conn,
  	       state_to_string(state), err);
  }
  
  static struct sk_buff *chan_alloc_skb_cb(struct l2cap_chan *chan,
  					 unsigned long hdr_len,
  					 unsigned long len, int nb)
  {
  	/* Note that we must allocate using GFP_ATOMIC here as
  	 * this function is called originally from netdev hard xmit
  	 * function in atomic context.
  	 */
  	return bt_skb_alloc(hdr_len + len, GFP_ATOMIC);
  }
  
  static void chan_suspend_cb(struct l2cap_chan *chan)
  {
  	struct sk_buff *skb = chan->data;
  
  	BT_DBG("chan %p conn %p skb %p", chan, chan->conn, skb);
  
  	if (!skb)
  		return;
  
  	lowpan_cb(skb)->status = -EAGAIN;
  }
  
  static void chan_resume_cb(struct l2cap_chan *chan)
  {
  	struct sk_buff *skb = chan->data;
  
  	BT_DBG("chan %p conn %p skb %p", chan, chan->conn, skb);
  
  	if (!skb)
  		return;
  
  	lowpan_cb(skb)->status = 0;
  }
  
  static long chan_get_sndtimeo_cb(struct l2cap_chan *chan)
  {
  	return L2CAP_CONN_TIMEOUT;
  }
  
  static const struct l2cap_ops bt_6lowpan_chan_ops = {
  	.name			= "L2CAP 6LoWPAN channel",
  	.new_connection		= chan_new_conn_cb,
  	.recv			= chan_recv_cb,
  	.close			= chan_close_cb,
  	.state_change		= chan_state_change_cb,
  	.ready			= chan_ready_cb,
  	.resume			= chan_resume_cb,
  	.suspend		= chan_suspend_cb,
  	.get_sndtimeo		= chan_get_sndtimeo_cb,
  	.alloc_skb		= chan_alloc_skb_cb,
  
  	.teardown		= l2cap_chan_no_teardown,
  	.defer			= l2cap_chan_no_defer,
  	.set_shutdown		= l2cap_chan_no_set_shutdown,
  };
  
  static inline __u8 bdaddr_type(__u8 type)
  {
  	if (type == ADDR_LE_DEV_PUBLIC)
  		return BDADDR_LE_PUBLIC;
  	else
  		return BDADDR_LE_RANDOM;
  }
  
  static int bt_6lowpan_connect(bdaddr_t *addr, u8 dst_type)
  {
  	struct l2cap_chan *chan;
  	int err;
  
  	chan = chan_create();
  	if (!chan)
  		return -EINVAL;
  
  	chan->ops = &bt_6lowpan_chan_ops;
  
  	err = l2cap_chan_connect(chan, cpu_to_le16(L2CAP_PSM_IPSP), 0,
  				 addr, dst_type);
  
  	BT_DBG("chan %p err %d", chan, err);
  	if (err < 0)
  		l2cap_chan_put(chan);
  
  	return err;
  }
  
  static int bt_6lowpan_disconnect(struct l2cap_conn *conn, u8 dst_type)
  {
  	struct lowpan_peer *peer;
  
  	BT_DBG("conn %p dst type %d", conn, dst_type);
  
  	peer = lookup_peer(conn);
  	if (!peer)
  		return -ENOENT;
  
  	BT_DBG("peer %p chan %p", peer, peer->chan);
  
  	l2cap_chan_close(peer->chan, ENOENT);
  
  	return 0;
  }
  
  static struct l2cap_chan *bt_6lowpan_listen(void)
  {
  	bdaddr_t *addr = BDADDR_ANY;
  	struct l2cap_chan *chan;
  	int err;
  
  	if (!enable_6lowpan)
  		return NULL;
  
  	chan = chan_create();
  	if (!chan)
  		return NULL;
  
  	chan->ops = &bt_6lowpan_chan_ops;
  	chan->state = BT_LISTEN;
  	chan->src_type = BDADDR_LE_PUBLIC;
  
  	atomic_set(&chan->nesting, L2CAP_NESTING_PARENT);
  
  	BT_DBG("chan %p src type %d", chan, chan->src_type);
  
  	err = l2cap_add_psm(chan, addr, cpu_to_le16(L2CAP_PSM_IPSP));
  	if (err) {
  		l2cap_chan_put(chan);
  		BT_ERR("psm cannot be added err %d", err);
  		return NULL;
  	}
  
  	return chan;
  }
  
  static int get_l2cap_conn(char *buf, bdaddr_t *addr, u8 *addr_type,
  			  struct l2cap_conn **conn)
  {
  	struct hci_conn *hcon;
  	struct hci_dev *hdev;
  	bdaddr_t *src = BDADDR_ANY;
  	int n;
  
  	n = sscanf(buf, "%hhx:%hhx:%hhx:%hhx:%hhx:%hhx %hhu",
  		   &addr->b[5], &addr->b[4], &addr->b[3],
  		   &addr->b[2], &addr->b[1], &addr->b[0],
  		   addr_type);
  
  	if (n < 7)
  		return -EINVAL;
  
  	hdev = hci_get_route(addr, src);
  	if (!hdev)
  		return -ENOENT;
  
  	hci_dev_lock(hdev);
  	hcon = hci_conn_hash_lookup_le(hdev, addr, *addr_type);
  	hci_dev_unlock(hdev);
  
  	if (!hcon)
  		return -ENOENT;
  
  	*conn = (struct l2cap_conn *)hcon->l2cap_data;
  
  	BT_DBG("conn %p dst %pMR type %d", *conn, &hcon->dst, hcon->dst_type);
  
  	return 0;
  }
  
  static void disconnect_all_peers(void)
  {
  	struct lowpan_btle_dev *entry;
  	struct lowpan_peer *peer, *tmp_peer, *new_peer;
  	struct list_head peers;
  
  	INIT_LIST_HEAD(&peers);
  
  	/* We make a separate list of peers as the close_cb() will
  	 * modify the device peers list so it is better not to mess
  	 * with the same list at the same time.
  	 */
  
  	rcu_read_lock();
  
  	list_for_each_entry_rcu(entry, &bt_6lowpan_devices, list) {
  		list_for_each_entry_rcu(peer, &entry->peers, list) {
  			new_peer = kmalloc(sizeof(*new_peer), GFP_ATOMIC);
  			if (!new_peer)
  				break;
  
  			new_peer->chan = peer->chan;
  			INIT_LIST_HEAD(&new_peer->list);
  
  			list_add(&new_peer->list, &peers);
  		}
  	}
  
  	rcu_read_unlock();
  
  	spin_lock(&devices_lock);
  	list_for_each_entry_safe(peer, tmp_peer, &peers, list) {
  		l2cap_chan_close(peer->chan, ENOENT);
  
  		list_del_rcu(&peer->list);
  		kfree_rcu(peer, rcu);
  	}
  	spin_unlock(&devices_lock);
  }
  
  struct set_enable {
  	struct work_struct work;
  	bool flag;
  };
  
  static void do_enable_set(struct work_struct *work)
  {
  	struct set_enable *set_enable = container_of(work,
  						     struct set_enable, work);
  
  	if (!set_enable->flag || enable_6lowpan != set_enable->flag)
  		/* Disconnect existing connections if 6lowpan is
  		 * disabled
  		 */
  		disconnect_all_peers();
  
  	enable_6lowpan = set_enable->flag;
  
  	if (listen_chan) {
  		l2cap_chan_close(listen_chan, 0);
  		l2cap_chan_put(listen_chan);
  	}
  
  	listen_chan = bt_6lowpan_listen();
  
  	kfree(set_enable);
  }
  
  static int lowpan_enable_set(void *data, u64 val)
  {
  	struct set_enable *set_enable;
  
  	set_enable = kzalloc(sizeof(*set_enable), GFP_KERNEL);
  	if (!set_enable)
  		return -ENOMEM;
  
  	set_enable->flag = !!val;
  	INIT_WORK(&set_enable->work, do_enable_set);
  
  	schedule_work(&set_enable->work);
  
  	return 0;
  }
  
  static int lowpan_enable_get(void *data, u64 *val)
  {
  	*val = enable_6lowpan;
  	return 0;
  }
  
  DEFINE_SIMPLE_ATTRIBUTE(lowpan_enable_fops, lowpan_enable_get,
  			lowpan_enable_set, "%llu\n");
  
  static ssize_t lowpan_control_write(struct file *fp,
  				    const char __user *user_buffer,
  				    size_t count,
  				    loff_t *position)
  {
  	char buf[32];
  	size_t buf_size = min(count, sizeof(buf) - 1);
  	int ret;
  	bdaddr_t addr;
  	u8 addr_type;
  	struct l2cap_conn *conn = NULL;
  
  	if (copy_from_user(buf, user_buffer, buf_size))
  		return -EFAULT;
  
  	buf[buf_size] = '\0';
  
  	if (memcmp(buf, "connect ", 8) == 0) {
  		ret = get_l2cap_conn(&buf[8], &addr, &addr_type, &conn);
  		if (ret == -EINVAL)
  			return ret;
  
  		if (listen_chan) {
  			l2cap_chan_close(listen_chan, 0);
  			l2cap_chan_put(listen_chan);
  			listen_chan = NULL;
  		}
  
  		if (conn) {
  			struct lowpan_peer *peer;
  
  			if (!is_bt_6lowpan(conn->hcon))
  				return -EINVAL;
  
  			peer = lookup_peer(conn);
  			if (peer) {
  				BT_DBG("6LoWPAN connection already exists");
  				return -EALREADY;
  			}
  
  			BT_DBG("conn %p dst %pMR type %d user %d", conn,
  			       &conn->hcon->dst, conn->hcon->dst_type,
  			       addr_type);
  		}
  
  		ret = bt_6lowpan_connect(&addr, addr_type);
  		if (ret < 0)
  			return ret;
  
  		return count;
  	}
  
  	if (memcmp(buf, "disconnect ", 11) == 0) {
  		ret = get_l2cap_conn(&buf[11], &addr, &addr_type, &conn);
  		if (ret < 0)
  			return ret;
  
  		ret = bt_6lowpan_disconnect(conn, addr_type);
  		if (ret < 0)
  			return ret;
  
  		return count;
  	}
  
  	return count;
  }
  
  static int lowpan_control_show(struct seq_file *f, void *ptr)
  {
  	struct lowpan_btle_dev *entry;
  	struct lowpan_peer *peer;
  
  	spin_lock(&devices_lock);
  
  	list_for_each_entry(entry, &bt_6lowpan_devices, list) {
  		list_for_each_entry(peer, &entry->peers, list)
  			seq_printf(f, "%pMR (type %u)\n",
  				   &peer->chan->dst, peer->chan->dst_type);
  	}
  
  	spin_unlock(&devices_lock);
  
  	return 0;
  }
  
  static int lowpan_control_open(struct inode *inode, struct file *file)
  {
  	return single_open(file, lowpan_control_show, inode->i_private);
  }
  
  static const struct file_operations lowpan_control_fops = {
  	.open		= lowpan_control_open,
  	.read		= seq_read,
  	.write		= lowpan_control_write,
  	.llseek		= seq_lseek,
  	.release	= single_release,
  };
  
  static void disconnect_devices(void)
  {
  	struct lowpan_btle_dev *entry, *tmp, *new_dev;
  	struct list_head devices;
  
  	INIT_LIST_HEAD(&devices);
  
  	/* We make a separate list of devices because the unregister_netdev()
  	 * will call device_event() which will also want to modify the same
  	 * devices list.
  	 */
  
  	rcu_read_lock();
  
  	list_for_each_entry_rcu(entry, &bt_6lowpan_devices, list) {
  		new_dev = kmalloc(sizeof(*new_dev), GFP_ATOMIC);
  		if (!new_dev)
  			break;
  
  		new_dev->netdev = entry->netdev;
  		INIT_LIST_HEAD(&new_dev->list);
  
  		list_add_rcu(&new_dev->list, &devices);
  	}
  
  	rcu_read_unlock();
  
  	list_for_each_entry_safe(entry, tmp, &devices, list) {
  		ifdown(entry->netdev);
  		BT_DBG("Unregistering netdev %s %p",
  		       entry->netdev->name, entry->netdev);
  		lowpan_unregister_netdev(entry->netdev);
  		kfree(entry);
  	}
  }
  
  static int device_event(struct notifier_block *unused,
  			unsigned long event, void *ptr)
  {
  	struct net_device *netdev = netdev_notifier_info_to_dev(ptr);
  	struct lowpan_btle_dev *entry;
  
  	if (netdev->type != ARPHRD_6LOWPAN)
  		return NOTIFY_DONE;
  
  	switch (event) {
  	case NETDEV_UNREGISTER:
  		spin_lock(&devices_lock);
  		list_for_each_entry(entry, &bt_6lowpan_devices, list) {
  			if (entry->netdev == netdev) {
  				BT_DBG("Unregistered netdev %s %p",
  				       netdev->name, netdev);
  				list_del(&entry->list);
  				break;
  			}
  		}
  		spin_unlock(&devices_lock);
  		break;
  	}
  
  	return NOTIFY_DONE;
  }
  
  static struct notifier_block bt_6lowpan_dev_notifier = {
  	.notifier_call = device_event,
  };
  
  static int __init bt_6lowpan_init(void)
  {
  	lowpan_enable_debugfs = debugfs_create_file("6lowpan_enable", 0644,
  						    bt_debugfs, NULL,
  						    &lowpan_enable_fops);
  	lowpan_control_debugfs = debugfs_create_file("6lowpan_control", 0644,
  						     bt_debugfs, NULL,
  						     &lowpan_control_fops);
  
  	return register_netdevice_notifier(&bt_6lowpan_dev_notifier);
  }
  
  static void __exit bt_6lowpan_exit(void)
  {
  	debugfs_remove(lowpan_enable_debugfs);
  	debugfs_remove(lowpan_control_debugfs);
  
  	if (listen_chan) {
  		l2cap_chan_close(listen_chan, 0);
  		l2cap_chan_put(listen_chan);
  	}
  
  	disconnect_devices();
  
  	unregister_netdevice_notifier(&bt_6lowpan_dev_notifier);
  }
  
  module_init(bt_6lowpan_init);
  module_exit(bt_6lowpan_exit);
  
  MODULE_AUTHOR("Jukka Rissanen <jukka.rissanen@linux.intel.com>");
  MODULE_DESCRIPTION("Bluetooth 6LoWPAN");
  MODULE_VERSION(VERSION);
  MODULE_LICENSE("GPL");
  