diff --git a/net/caif/caif_socket.c b/net/caif/caif_socket.c
new file mode 100644
index 0000000..aa209b1
--- /dev/null
+++ b/net/caif/caif_socket.c
@@ -0,0 +1,1121 @@
+/*
+ * Copyright (C) ST-Ericsson AB 2010
+ * Author:	Sjur Brendeland
+ * License terms: GNU General Public License (GPL) version 2
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__
+
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+#include <linux/mutex.h>
+#include <linux/list.h>
+#include <linux/wait.h>
+#include <linux/poll.h>
+#include <linux/tcp.h>
+#include <linux/uaccess.h>
+#include <linux/debugfs.h>
+#include <linux/caif/caif_socket.h>
+#include <linux/pkt_sched.h>
+#include <net/sock.h>
+#include <net/tcp_states.h>
+#include <net/caif/caif_layer.h>
+#include <net/caif/caif_dev.h>
+#include <net/caif/cfpkt.h>
+
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_NETPROTO(AF_CAIF);
+
+/*
+ * CAIF state is re-using the TCP socket states.
+ * caif_states stored in sk_state reflect the state as reported by
+ * the CAIF stack, while sk_socket->state is the state of the socket.
+ */
+enum caif_states {
+	CAIF_CONNECTED		= TCP_ESTABLISHED,
+	CAIF_CONNECTING	= TCP_SYN_SENT,
+	CAIF_DISCONNECTED	= TCP_CLOSE
+};
+
+#define TX_FLOW_ON_BIT	1
+#define RX_FLOW_ON_BIT	2
+
+struct caifsock {
+	struct sock sk; /* must be first member */
+	struct cflayer layer;
+	u32 flow_state;
+	struct caif_connect_request conn_req;
+	struct mutex readlock;
+	struct dentry *debugfs_socket_dir;
+	int headroom, tailroom, maxframe;
+};
+
+static int rx_flow_is_on(struct caifsock *cf_sk)
+{
+	return test_bit(RX_FLOW_ON_BIT,
+			(void *) &cf_sk->flow_state);
+}
+
+static int tx_flow_is_on(struct caifsock *cf_sk)
+{
+	return test_bit(TX_FLOW_ON_BIT,
+			(void *) &cf_sk->flow_state);
+}
+
+static void set_rx_flow_off(struct caifsock *cf_sk)
+{
+	 clear_bit(RX_FLOW_ON_BIT,
+		 (void *) &cf_sk->flow_state);
+}
+
+static void set_rx_flow_on(struct caifsock *cf_sk)
+{
+	 set_bit(RX_FLOW_ON_BIT,
+			(void *) &cf_sk->flow_state);
+}
+
+static void set_tx_flow_off(struct caifsock *cf_sk)
+{
+	 clear_bit(TX_FLOW_ON_BIT,
+		(void *) &cf_sk->flow_state);
+}
+
+static void set_tx_flow_on(struct caifsock *cf_sk)
+{
+	 set_bit(TX_FLOW_ON_BIT,
+		(void *) &cf_sk->flow_state);
+}
+
+static void caif_read_lock(struct sock *sk)
+{
+	struct caifsock *cf_sk;
+	cf_sk = container_of(sk, struct caifsock, sk);
+	mutex_lock(&cf_sk->readlock);
+}
+
+static void caif_read_unlock(struct sock *sk)
+{
+	struct caifsock *cf_sk;
+	cf_sk = container_of(sk, struct caifsock, sk);
+	mutex_unlock(&cf_sk->readlock);
+}
+
+static int sk_rcvbuf_lowwater(struct caifsock *cf_sk)
+{
+	/* A quarter of full buffer is used a low water mark */
+	return cf_sk->sk.sk_rcvbuf / 4;
+}
+
+static void caif_flow_ctrl(struct sock *sk, int mode)
+{
+	struct caifsock *cf_sk;
+	cf_sk = container_of(sk, struct caifsock, sk);
+	if (cf_sk->layer.dn && cf_sk->layer.dn->modemcmd)
+		cf_sk->layer.dn->modemcmd(cf_sk->layer.dn, mode);
+}
+
+/*
+ * Copied from sock.c:sock_queue_rcv_skb(), but changed so packets are
+ * not dropped, but CAIF is sending flow off instead.
+ */
+static void caif_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
+{
+	int err;
+	unsigned long flags;
+	struct sk_buff_head *list = &sk->sk_receive_queue;
+	struct caifsock *cf_sk = container_of(sk, struct caifsock, sk);
+	bool queued = false;
+
+	if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
+		(unsigned int)sk->sk_rcvbuf && rx_flow_is_on(cf_sk)) {
+		net_dbg_ratelimited("sending flow OFF (queue len = %d %d)\n",
+				    atomic_read(&cf_sk->sk.sk_rmem_alloc),
+				    sk_rcvbuf_lowwater(cf_sk));
+		set_rx_flow_off(cf_sk);
+		caif_flow_ctrl(sk, CAIF_MODEMCMD_FLOW_OFF_REQ);
+	}
+
+	err = sk_filter(sk, skb);
+	if (err)
+		goto out;
+
+	if (!sk_rmem_schedule(sk, skb, skb->truesize) && rx_flow_is_on(cf_sk)) {
+		set_rx_flow_off(cf_sk);
+		net_dbg_ratelimited("sending flow OFF due to rmem_schedule\n");
+		caif_flow_ctrl(sk, CAIF_MODEMCMD_FLOW_OFF_REQ);
+	}
+	skb->dev = NULL;
+	skb_set_owner_r(skb, sk);
+	spin_lock_irqsave(&list->lock, flags);
+	queued = !sock_flag(sk, SOCK_DEAD);
+	if (queued)
+		__skb_queue_tail(list, skb);
+	spin_unlock_irqrestore(&list->lock, flags);
+out:
+	if (queued)
+		sk->sk_data_ready(sk);
+	else
+		kfree_skb(skb);
+}
+
+/* Packet Receive Callback function called from CAIF Stack */
+static int caif_sktrecv_cb(struct cflayer *layr, struct cfpkt *pkt)
+{
+	struct caifsock *cf_sk;
+	struct sk_buff *skb;
+
+	cf_sk = container_of(layr, struct caifsock, layer);
+	skb = cfpkt_tonative(pkt);
+
+	if (unlikely(cf_sk->sk.sk_state != CAIF_CONNECTED)) {
+		kfree_skb(skb);
+		return 0;
+	}
+	caif_queue_rcv_skb(&cf_sk->sk, skb);
+	return 0;
+}
+
+static void cfsk_hold(struct cflayer *layr)
+{
+	struct caifsock *cf_sk = container_of(layr, struct caifsock, layer);
+	sock_hold(&cf_sk->sk);
+}
+
+static void cfsk_put(struct cflayer *layr)
+{
+	struct caifsock *cf_sk = container_of(layr, struct caifsock, layer);
+	sock_put(&cf_sk->sk);
+}
+
+/* Packet Control Callback function called from CAIF */
+static void caif_ctrl_cb(struct cflayer *layr,
+			 enum caif_ctrlcmd flow,
+			 int phyid)
+{
+	struct caifsock *cf_sk = container_of(layr, struct caifsock, layer);
+	switch (flow) {
+	case CAIF_CTRLCMD_FLOW_ON_IND:
+		/* OK from modem to start sending again */
+		set_tx_flow_on(cf_sk);
+		cf_sk->sk.sk_state_change(&cf_sk->sk);
+		break;
+
+	case CAIF_CTRLCMD_FLOW_OFF_IND:
+		/* Modem asks us to shut up */
+		set_tx_flow_off(cf_sk);
+		cf_sk->sk.sk_state_change(&cf_sk->sk);
+		break;
+
+	case CAIF_CTRLCMD_INIT_RSP:
+		/* We're now connected */
+		caif_client_register_refcnt(&cf_sk->layer,
+						cfsk_hold, cfsk_put);
+		cf_sk->sk.sk_state = CAIF_CONNECTED;
+		set_tx_flow_on(cf_sk);
+		cf_sk->sk.sk_shutdown = 0;
+		cf_sk->sk.sk_state_change(&cf_sk->sk);
+		break;
+
+	case CAIF_CTRLCMD_DEINIT_RSP:
+		/* We're now disconnected */
+		cf_sk->sk.sk_state = CAIF_DISCONNECTED;
+		cf_sk->sk.sk_state_change(&cf_sk->sk);
+		break;
+
+	case CAIF_CTRLCMD_INIT_FAIL_RSP:
+		/* Connect request failed */
+		cf_sk->sk.sk_err = ECONNREFUSED;
+		cf_sk->sk.sk_state = CAIF_DISCONNECTED;
+		cf_sk->sk.sk_shutdown = SHUTDOWN_MASK;
+		/*
+		 * Socket "standards" seems to require POLLOUT to
+		 * be set at connect failure.
+		 */
+		set_tx_flow_on(cf_sk);
+		cf_sk->sk.sk_state_change(&cf_sk->sk);
+		break;
+
+	case CAIF_CTRLCMD_REMOTE_SHUTDOWN_IND:
+		/* Modem has closed this connection, or device is down. */
+		cf_sk->sk.sk_shutdown = SHUTDOWN_MASK;
+		cf_sk->sk.sk_err = ECONNRESET;
+		set_rx_flow_on(cf_sk);
+		cf_sk->sk.sk_error_report(&cf_sk->sk);
+		break;
+
+	default:
+		pr_debug("Unexpected flow command %d\n", flow);
+	}
+}
+
+static void caif_check_flow_release(struct sock *sk)
+{
+	struct caifsock *cf_sk = container_of(sk, struct caifsock, sk);
+
+	if (rx_flow_is_on(cf_sk))
+		return;
+
+	if (atomic_read(&sk->sk_rmem_alloc) <= sk_rcvbuf_lowwater(cf_sk)) {
+			set_rx_flow_on(cf_sk);
+			caif_flow_ctrl(sk, CAIF_MODEMCMD_FLOW_ON_REQ);
+	}
+}
+
+/*
+ * Copied from unix_dgram_recvmsg, but removed credit checks,
+ * changed locking, address handling and added MSG_TRUNC.
+ */
+static int caif_seqpkt_recvmsg(struct socket *sock, struct msghdr *m,
+			       size_t len, int flags)
+
+{
+	struct sock *sk = sock->sk;
+	struct sk_buff *skb;
+	int ret;
+	int copylen;
+
+	ret = -EOPNOTSUPP;
+	if (flags & MSG_OOB)
+		goto read_error;
+
+	skb = skb_recv_datagram(sk, flags, 0 , &ret);
+	if (!skb)
+		goto read_error;
+	copylen = skb->len;
+	if (len < copylen) {
+		m->msg_flags |= MSG_TRUNC;
+		copylen = len;
+	}
+
+	ret = skb_copy_datagram_msg(skb, 0, m, copylen);
+	if (ret)
+		goto out_free;
+
+	ret = (flags & MSG_TRUNC) ? skb->len : copylen;
+out_free:
+	skb_free_datagram(sk, skb);
+	caif_check_flow_release(sk);
+	return ret;
+
+read_error:
+	return ret;
+}
+
+
+/* Copied from unix_stream_wait_data, identical except for lock call. */
+static long caif_stream_data_wait(struct sock *sk, long timeo)
+{
+	DEFINE_WAIT(wait);
+	lock_sock(sk);
+
+	for (;;) {
+		prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
+
+		if (!skb_queue_empty(&sk->sk_receive_queue) ||
+			sk->sk_err ||
+			sk->sk_state != CAIF_CONNECTED ||
+			sock_flag(sk, SOCK_DEAD) ||
+			(sk->sk_shutdown & RCV_SHUTDOWN) ||
+			signal_pending(current) ||
+			!timeo)
+			break;
+
+		sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
+		release_sock(sk);
+		timeo = schedule_timeout(timeo);
+		lock_sock(sk);
+
+		if (sock_flag(sk, SOCK_DEAD))
+			break;
+
+		sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
+	}
+
+	finish_wait(sk_sleep(sk), &wait);
+	release_sock(sk);
+	return timeo;
+}
+
+
+/*
+ * Copied from unix_stream_recvmsg, but removed credit checks,
+ * changed locking calls, changed address handling.
+ */
+static int caif_stream_recvmsg(struct socket *sock, struct msghdr *msg,
+			       size_t size, int flags)
+{
+	struct sock *sk = sock->sk;
+	int copied = 0;
+	int target;
+	int err = 0;
+	long timeo;
+
+	err = -EOPNOTSUPP;
+	if (flags&MSG_OOB)
+		goto out;
+
+	/*
+	 * Lock the socket to prevent queue disordering
+	 * while sleeps in memcpy_tomsg
+	 */
+	err = -EAGAIN;
+	if (sk->sk_state == CAIF_CONNECTING)
+		goto out;
+
+	caif_read_lock(sk);
+	target = sock_rcvlowat(sk, flags&MSG_WAITALL, size);
+	timeo = sock_rcvtimeo(sk, flags&MSG_DONTWAIT);
+
+	do {
+		int chunk;
+		struct sk_buff *skb;
+
+		lock_sock(sk);
+		if (sock_flag(sk, SOCK_DEAD)) {
+			err = -ECONNRESET;
+			goto unlock;
+		}
+		skb = skb_dequeue(&sk->sk_receive_queue);
+		caif_check_flow_release(sk);
+
+		if (skb == NULL) {
+			if (copied >= target)
+				goto unlock;
+			/*
+			 *	POSIX 1003.1g mandates this order.
+			 */
+			err = sock_error(sk);
+			if (err)
+				goto unlock;
+			err = -ECONNRESET;
+			if (sk->sk_shutdown & RCV_SHUTDOWN)
+				goto unlock;
+
+			err = -EPIPE;
+			if (sk->sk_state != CAIF_CONNECTED)
+				goto unlock;
+			if (sock_flag(sk, SOCK_DEAD))
+				goto unlock;
+
+			release_sock(sk);
+
+			err = -EAGAIN;
+			if (!timeo)
+				break;
+
+			caif_read_unlock(sk);
+
+			timeo = caif_stream_data_wait(sk, timeo);
+
+			if (signal_pending(current)) {
+				err = sock_intr_errno(timeo);
+				goto out;
+			}
+			caif_read_lock(sk);
+			continue;
+unlock:
+			release_sock(sk);
+			break;
+		}
+		release_sock(sk);
+		chunk = min_t(unsigned int, skb->len, size);
+		if (memcpy_to_msg(msg, skb->data, chunk)) {
+			skb_queue_head(&sk->sk_receive_queue, skb);
+			if (copied == 0)
+				copied = -EFAULT;
+			break;
+		}
+		copied += chunk;
+		size -= chunk;
+
+		/* Mark read part of skb as used */
+		if (!(flags & MSG_PEEK)) {
+			skb_pull(skb, chunk);
+
+			/* put the skb back if we didn't use it up. */
+			if (skb->len) {
+				skb_queue_head(&sk->sk_receive_queue, skb);
+				break;
+			}
+			kfree_skb(skb);
+
+		} else {
+			/*
+			 * It is questionable, see note in unix_dgram_recvmsg.
+			 */
+			/* put message back and return */
+			skb_queue_head(&sk->sk_receive_queue, skb);
+			break;
+		}
+	} while (size);
+	caif_read_unlock(sk);
+
+out:
+	return copied ? : err;
+}
+
+/*
+ * Copied from sock.c:sock_wait_for_wmem, but change to wait for
+ * CAIF flow-on and sock_writable.
+ */
+static long caif_wait_for_flow_on(struct caifsock *cf_sk,
+				  int wait_writeable, long timeo, int *err)
+{
+	struct sock *sk = &cf_sk->sk;
+	DEFINE_WAIT(wait);
+	for (;;) {
+		*err = 0;
+		if (tx_flow_is_on(cf_sk) &&
+			(!wait_writeable || sock_writeable(&cf_sk->sk)))
+			break;
+		*err = -ETIMEDOUT;
+		if (!timeo)
+			break;
+		*err = -ERESTARTSYS;
+		if (signal_pending(current))
+			break;
+		prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
+		*err = -ECONNRESET;
+		if (sk->sk_shutdown & SHUTDOWN_MASK)
+			break;
+		*err = -sk->sk_err;
+		if (sk->sk_err)
+			break;
+		*err = -EPIPE;
+		if (cf_sk->sk.sk_state != CAIF_CONNECTED)
+			break;
+		timeo = schedule_timeout(timeo);
+	}
+	finish_wait(sk_sleep(sk), &wait);
+	return timeo;
+}
+
+/*
+ * Transmit a SKB. The device may temporarily request re-transmission
+ * by returning EAGAIN.
+ */
+static int transmit_skb(struct sk_buff *skb, struct caifsock *cf_sk,
+			int noblock, long timeo)
+{
+	struct cfpkt *pkt;
+
+	pkt = cfpkt_fromnative(CAIF_DIR_OUT, skb);
+	memset(skb->cb, 0, sizeof(struct caif_payload_info));
+	cfpkt_set_prio(pkt, cf_sk->sk.sk_priority);
+
+	if (cf_sk->layer.dn == NULL) {
+		kfree_skb(skb);
+		return -EINVAL;
+	}
+
+	return cf_sk->layer.dn->transmit(cf_sk->layer.dn, pkt);
+}
+
+/* Copied from af_unix:unix_dgram_sendmsg, and adapted to CAIF */
+static int caif_seqpkt_sendmsg(struct socket *sock, struct msghdr *msg,
+			       size_t len)
+{
+	struct sock *sk = sock->sk;
+	struct caifsock *cf_sk = container_of(sk, struct caifsock, sk);
+	int buffer_size;
+	int ret = 0;
+	struct sk_buff *skb = NULL;
+	int noblock;
+	long timeo;
+	caif_assert(cf_sk);
+	ret = sock_error(sk);
+	if (ret)
+		goto err;
+
+	ret = -EOPNOTSUPP;
+	if (msg->msg_flags&MSG_OOB)
+		goto err;
+
+	ret = -EOPNOTSUPP;
+	if (msg->msg_namelen)
+		goto err;
+
+	ret = -EINVAL;
+	if (unlikely(msg->msg_iter.iov->iov_base == NULL))
+		goto err;
+	noblock = msg->msg_flags & MSG_DONTWAIT;
+
+	timeo = sock_sndtimeo(sk, noblock);
+	timeo = caif_wait_for_flow_on(container_of(sk, struct caifsock, sk),
+				1, timeo, &ret);
+
+	if (ret)
+		goto err;
+	ret = -EPIPE;
+	if (cf_sk->sk.sk_state != CAIF_CONNECTED ||
+		sock_flag(sk, SOCK_DEAD) ||
+		(sk->sk_shutdown & RCV_SHUTDOWN))
+		goto err;
+
+	/* Error if trying to write more than maximum frame size. */
+	ret = -EMSGSIZE;
+	if (len > cf_sk->maxframe && cf_sk->sk.sk_protocol != CAIFPROTO_RFM)
+		goto err;
+
+	buffer_size = len + cf_sk->headroom + cf_sk->tailroom;
+
+	ret = -ENOMEM;
+	skb = sock_alloc_send_skb(sk, buffer_size, noblock, &ret);
+
+	if (!skb || skb_tailroom(skb) < buffer_size)
+		goto err;
+
+	skb_reserve(skb, cf_sk->headroom);
+
+	ret = memcpy_from_msg(skb_put(skb, len), msg, len);
+
+	if (ret)
+		goto err;
+	ret = transmit_skb(skb, cf_sk, noblock, timeo);
+	if (ret < 0)
+		/* skb is already freed */
+		return ret;
+
+	return len;
+err:
+	kfree_skb(skb);
+	return ret;
+}
+
+/*
+ * Copied from unix_stream_sendmsg and adapted to CAIF:
+ * Changed removed permission handling and added waiting for flow on
+ * and other minor adaptations.
+ */
+static int caif_stream_sendmsg(struct socket *sock, struct msghdr *msg,
+			       size_t len)
+{
+	struct sock *sk = sock->sk;
+	struct caifsock *cf_sk = container_of(sk, struct caifsock, sk);
+	int err, size;
+	struct sk_buff *skb;
+	int sent = 0;
+	long timeo;
+
+	err = -EOPNOTSUPP;
+	if (unlikely(msg->msg_flags&MSG_OOB))
+		goto out_err;
+
+	if (unlikely(msg->msg_namelen))
+		goto out_err;
+
+	timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
+	timeo = caif_wait_for_flow_on(cf_sk, 1, timeo, &err);
+
+	if (unlikely(sk->sk_shutdown & SEND_SHUTDOWN))
+		goto pipe_err;
+
+	while (sent < len) {
+
+		size = len-sent;
+
+		if (size > cf_sk->maxframe)
+			size = cf_sk->maxframe;
+
+		/* If size is more than half of sndbuf, chop up message */
+		if (size > ((sk->sk_sndbuf >> 1) - 64))
+			size = (sk->sk_sndbuf >> 1) - 64;
+
+		if (size > SKB_MAX_ALLOC)
+			size = SKB_MAX_ALLOC;
+
+		skb = sock_alloc_send_skb(sk,
+					size + cf_sk->headroom +
+					cf_sk->tailroom,
+					msg->msg_flags&MSG_DONTWAIT,
+					&err);
+		if (skb == NULL)
+			goto out_err;
+
+		skb_reserve(skb, cf_sk->headroom);
+		/*
+		 *	If you pass two values to the sock_alloc_send_skb
+		 *	it tries to grab the large buffer with GFP_NOFS
+		 *	(which can fail easily), and if it fails grab the
+		 *	fallback size buffer which is under a page and will
+		 *	succeed. [Alan]
+		 */
+		size = min_t(int, size, skb_tailroom(skb));
+
+		err = memcpy_from_msg(skb_put(skb, size), msg, size);
+		if (err) {
+			kfree_skb(skb);
+			goto out_err;
+		}
+		err = transmit_skb(skb, cf_sk,
+				msg->msg_flags&MSG_DONTWAIT, timeo);
+		if (err < 0)
+			/* skb is already freed */
+			goto pipe_err;
+
+		sent += size;
+	}
+
+	return sent;
+
+pipe_err:
+	if (sent == 0 && !(msg->msg_flags&MSG_NOSIGNAL))
+		send_sig(SIGPIPE, current, 0);
+	err = -EPIPE;
+out_err:
+	return sent ? : err;
+}
+
+static int setsockopt(struct socket *sock,
+		      int lvl, int opt, char __user *ov, unsigned int ol)
+{
+	struct sock *sk = sock->sk;
+	struct caifsock *cf_sk = container_of(sk, struct caifsock, sk);
+	int linksel;
+
+	if (cf_sk->sk.sk_socket->state != SS_UNCONNECTED)
+		return -ENOPROTOOPT;
+
+	switch (opt) {
+	case CAIFSO_LINK_SELECT:
+		if (ol < sizeof(int))
+			return -EINVAL;
+		if (lvl != SOL_CAIF)
+			goto bad_sol;
+		if (copy_from_user(&linksel, ov, sizeof(int)))
+			return -EINVAL;
+		lock_sock(&(cf_sk->sk));
+		cf_sk->conn_req.link_selector = linksel;
+		release_sock(&cf_sk->sk);
+		return 0;
+
+	case CAIFSO_REQ_PARAM:
+		if (lvl != SOL_CAIF)
+			goto bad_sol;
+		if (cf_sk->sk.sk_protocol != CAIFPROTO_UTIL)
+			return -ENOPROTOOPT;
+		lock_sock(&(cf_sk->sk));
+		if (ol > sizeof(cf_sk->conn_req.param.data) ||
+			copy_from_user(&cf_sk->conn_req.param.data, ov, ol)) {
+			release_sock(&cf_sk->sk);
+			return -EINVAL;
+		}
+		cf_sk->conn_req.param.size = ol;
+		release_sock(&cf_sk->sk);
+		return 0;
+
+	default:
+		return -ENOPROTOOPT;
+	}
+
+	return 0;
+bad_sol:
+	return -ENOPROTOOPT;
+
+}
+
+/*
+ * caif_connect() - Connect a CAIF Socket
+ * Copied and modified af_irda.c:irda_connect().
+ *
+ * Note : by consulting "errno", the user space caller may learn the cause
+ * of the failure. Most of them are visible in the function, others may come
+ * from subroutines called and are listed here :
+ *  o -EAFNOSUPPORT: bad socket family or type.
+ *  o -ESOCKTNOSUPPORT: bad socket type or protocol
+ *  o -EINVAL: bad socket address, or CAIF link type
+ *  o -ECONNREFUSED: remote end refused the connection.
+ *  o -EINPROGRESS: connect request sent but timed out (or non-blocking)
+ *  o -EISCONN: already connected.
+ *  o -ETIMEDOUT: Connection timed out (send timeout)
+ *  o -ENODEV: No link layer to send request
+ *  o -ECONNRESET: Received Shutdown indication or lost link layer
+ *  o -ENOMEM: Out of memory
+ *
+ *  State Strategy:
+ *  o sk_state: holds the CAIF_* protocol state, it's updated by
+ *	caif_ctrl_cb.
+ *  o sock->state: holds the SS_* socket state and is updated by connect and
+ *	disconnect.
+ */
+static int caif_connect(struct socket *sock, struct sockaddr *uaddr,
+			int addr_len, int flags)
+{
+	struct sock *sk = sock->sk;
+	struct caifsock *cf_sk = container_of(sk, struct caifsock, sk);
+	long timeo;
+	int err;
+	int ifindex, headroom, tailroom;
+	unsigned int mtu;
+	struct net_device *dev;
+
+	lock_sock(sk);
+
+	err = -EAFNOSUPPORT;
+	if (uaddr->sa_family != AF_CAIF)
+		goto out;
+
+	switch (sock->state) {
+	case SS_UNCONNECTED:
+		/* Normal case, a fresh connect */
+		caif_assert(sk->sk_state == CAIF_DISCONNECTED);
+		break;
+	case SS_CONNECTING:
+		switch (sk->sk_state) {
+		case CAIF_CONNECTED:
+			sock->state = SS_CONNECTED;
+			err = -EISCONN;
+			goto out;
+		case CAIF_DISCONNECTED:
+			/* Reconnect allowed */
+			break;
+		case CAIF_CONNECTING:
+			err = -EALREADY;
+			if (flags & O_NONBLOCK)
+				goto out;
+			goto wait_connect;
+		}
+		break;
+	case SS_CONNECTED:
+		caif_assert(sk->sk_state == CAIF_CONNECTED ||
+				sk->sk_state == CAIF_DISCONNECTED);
+		if (sk->sk_shutdown & SHUTDOWN_MASK) {
+			/* Allow re-connect after SHUTDOWN_IND */
+			caif_disconnect_client(sock_net(sk), &cf_sk->layer);
+			caif_free_client(&cf_sk->layer);
+			break;
+		}
+		/* No reconnect on a seqpacket socket */
+		err = -EISCONN;
+		goto out;
+	case SS_DISCONNECTING:
+	case SS_FREE:
+		caif_assert(1); /*Should never happen */
+		break;
+	}
+	sk->sk_state = CAIF_DISCONNECTED;
+	sock->state = SS_UNCONNECTED;
+	sk_stream_kill_queues(&cf_sk->sk);
+
+	err = -EINVAL;
+	if (addr_len != sizeof(struct sockaddr_caif))
+		goto out;
+
+	memcpy(&cf_sk->conn_req.sockaddr, uaddr,
+		sizeof(struct sockaddr_caif));
+
+	/* Move to connecting socket, start sending Connect Requests */
+	sock->state = SS_CONNECTING;
+	sk->sk_state = CAIF_CONNECTING;
+
+	/* Check priority value comming from socket */
+	/* if priority value is out of range it will be ajusted */
+	if (cf_sk->sk.sk_priority > CAIF_PRIO_MAX)
+		cf_sk->conn_req.priority = CAIF_PRIO_MAX;
+	else if (cf_sk->sk.sk_priority < CAIF_PRIO_MIN)
+		cf_sk->conn_req.priority = CAIF_PRIO_MIN;
+	else
+		cf_sk->conn_req.priority = cf_sk->sk.sk_priority;
+
+	/*ifindex = id of the interface.*/
+	cf_sk->conn_req.ifindex = cf_sk->sk.sk_bound_dev_if;
+
+	cf_sk->layer.receive = caif_sktrecv_cb;
+
+	err = caif_connect_client(sock_net(sk), &cf_sk->conn_req,
+				&cf_sk->layer, &ifindex, &headroom, &tailroom);
+
+	if (err < 0) {
+		cf_sk->sk.sk_socket->state = SS_UNCONNECTED;
+		cf_sk->sk.sk_state = CAIF_DISCONNECTED;
+		goto out;
+	}
+
+	err = -ENODEV;
+	rcu_read_lock();
+	dev = dev_get_by_index_rcu(sock_net(sk), ifindex);
+	if (!dev) {
+		rcu_read_unlock();
+		goto out;
+	}
+	cf_sk->headroom = LL_RESERVED_SPACE_EXTRA(dev, headroom);
+	mtu = dev->mtu;
+	rcu_read_unlock();
+
+	cf_sk->tailroom = tailroom;
+	cf_sk->maxframe = mtu - (headroom + tailroom);
+	if (cf_sk->maxframe < 1) {
+		pr_warn("CAIF Interface MTU too small (%d)\n", dev->mtu);
+		err = -ENODEV;
+		goto out;
+	}
+
+	err = -EINPROGRESS;
+wait_connect:
+
+	if (sk->sk_state != CAIF_CONNECTED && (flags & O_NONBLOCK))
+		goto out;
+
+	timeo = sock_sndtimeo(sk, flags & O_NONBLOCK);
+
+	release_sock(sk);
+	err = -ERESTARTSYS;
+	timeo = wait_event_interruptible_timeout(*sk_sleep(sk),
+			sk->sk_state != CAIF_CONNECTING,
+			timeo);
+	lock_sock(sk);
+	if (timeo < 0)
+		goto out; /* -ERESTARTSYS */
+
+	err = -ETIMEDOUT;
+	if (timeo == 0 && sk->sk_state != CAIF_CONNECTED)
+		goto out;
+	if (sk->sk_state != CAIF_CONNECTED) {
+		sock->state = SS_UNCONNECTED;
+		err = sock_error(sk);
+		if (!err)
+			err = -ECONNREFUSED;
+		goto out;
+	}
+	sock->state = SS_CONNECTED;
+	err = 0;
+out:
+	release_sock(sk);
+	return err;
+}
+
+/*
+ * caif_release() - Disconnect a CAIF Socket
+ * Copied and modified af_irda.c:irda_release().
+ */
+static int caif_release(struct socket *sock)
+{
+	struct sock *sk = sock->sk;
+	struct caifsock *cf_sk = container_of(sk, struct caifsock, sk);
+
+	if (!sk)
+		return 0;
+
+	set_tx_flow_off(cf_sk);
+
+	/*
+	 * Ensure that packets are not queued after this point in time.
+	 * caif_queue_rcv_skb checks SOCK_DEAD holding the queue lock,
+	 * this ensures no packets when sock is dead.
+	 */
+	spin_lock_bh(&sk->sk_receive_queue.lock);
+	sock_set_flag(sk, SOCK_DEAD);
+	spin_unlock_bh(&sk->sk_receive_queue.lock);
+	sock->sk = NULL;
+
+	WARN_ON(IS_ERR(cf_sk->debugfs_socket_dir));
+	debugfs_remove_recursive(cf_sk->debugfs_socket_dir);
+
+	lock_sock(&(cf_sk->sk));
+	sk->sk_state = CAIF_DISCONNECTED;
+	sk->sk_shutdown = SHUTDOWN_MASK;
+
+	caif_disconnect_client(sock_net(sk), &cf_sk->layer);
+	cf_sk->sk.sk_socket->state = SS_DISCONNECTING;
+	wake_up_interruptible_poll(sk_sleep(sk), POLLERR|POLLHUP);
+
+	sock_orphan(sk);
+	sk_stream_kill_queues(&cf_sk->sk);
+	release_sock(sk);
+	sock_put(sk);
+	return 0;
+}
+
+/* Copied from af_unix.c:unix_poll(), added CAIF tx_flow handling */
+static unsigned int caif_poll(struct file *file,
+			      struct socket *sock, poll_table *wait)
+{
+	struct sock *sk = sock->sk;
+	unsigned int mask;
+	struct caifsock *cf_sk = container_of(sk, struct caifsock, sk);
+
+	sock_poll_wait(file, sk_sleep(sk), wait);
+	mask = 0;
+
+	/* exceptional events? */
+	if (sk->sk_err)
+		mask |= POLLERR;
+	if (sk->sk_shutdown == SHUTDOWN_MASK)
+		mask |= POLLHUP;
+	if (sk->sk_shutdown & RCV_SHUTDOWN)
+		mask |= POLLRDHUP;
+
+	/* readable? */
+	if (!skb_queue_empty(&sk->sk_receive_queue) ||
+		(sk->sk_shutdown & RCV_SHUTDOWN))
+		mask |= POLLIN | POLLRDNORM;
+
+	/*
+	 * we set writable also when the other side has shut down the
+	 * connection. This prevents stuck sockets.
+	 */
+	if (sock_writeable(sk) && tx_flow_is_on(cf_sk))
+		mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
+
+	return mask;
+}
+
+static const struct proto_ops caif_seqpacket_ops = {
+	.family = PF_CAIF,
+	.owner = THIS_MODULE,
+	.release = caif_release,
+	.bind = sock_no_bind,
+	.connect = caif_connect,
+	.socketpair = sock_no_socketpair,
+	.accept = sock_no_accept,
+	.getname = sock_no_getname,
+	.poll = caif_poll,
+	.ioctl = sock_no_ioctl,
+	.listen = sock_no_listen,
+	.shutdown = sock_no_shutdown,
+	.setsockopt = setsockopt,
+	.getsockopt = sock_no_getsockopt,
+	.sendmsg = caif_seqpkt_sendmsg,
+	.recvmsg = caif_seqpkt_recvmsg,
+	.mmap = sock_no_mmap,
+	.sendpage = sock_no_sendpage,
+};
+
+static const struct proto_ops caif_stream_ops = {
+	.family = PF_CAIF,
+	.owner = THIS_MODULE,
+	.release = caif_release,
+	.bind = sock_no_bind,
+	.connect = caif_connect,
+	.socketpair = sock_no_socketpair,
+	.accept = sock_no_accept,
+	.getname = sock_no_getname,
+	.poll = caif_poll,
+	.ioctl = sock_no_ioctl,
+	.listen = sock_no_listen,
+	.shutdown = sock_no_shutdown,
+	.setsockopt = setsockopt,
+	.getsockopt = sock_no_getsockopt,
+	.sendmsg = caif_stream_sendmsg,
+	.recvmsg = caif_stream_recvmsg,
+	.mmap = sock_no_mmap,
+	.sendpage = sock_no_sendpage,
+};
+
+/* This function is called when a socket is finally destroyed. */
+static void caif_sock_destructor(struct sock *sk)
+{
+	struct caifsock *cf_sk = container_of(sk, struct caifsock, sk);
+	caif_assert(!atomic_read(&sk->sk_wmem_alloc));
+	caif_assert(sk_unhashed(sk));
+	caif_assert(!sk->sk_socket);
+	if (!sock_flag(sk, SOCK_DEAD)) {
+		pr_debug("Attempt to release alive CAIF socket: %p\n", sk);
+		return;
+	}
+	sk_stream_kill_queues(&cf_sk->sk);
+	caif_free_client(&cf_sk->layer);
+}
+
+static int caif_create(struct net *net, struct socket *sock, int protocol,
+		       int kern)
+{
+	struct sock *sk = NULL;
+	struct caifsock *cf_sk = NULL;
+	static struct proto prot = {.name = "PF_CAIF",
+		.owner = THIS_MODULE,
+		.obj_size = sizeof(struct caifsock),
+	};
+
+	if (!capable(CAP_SYS_ADMIN) && !capable(CAP_NET_ADMIN))
+		return -EPERM;
+	/*
+	 * The sock->type specifies the socket type to use.
+	 * The CAIF socket is a packet stream in the sense
+	 * that it is packet based. CAIF trusts the reliability
+	 * of the link, no resending is implemented.
+	 */
+	if (sock->type == SOCK_SEQPACKET)
+		sock->ops = &caif_seqpacket_ops;
+	else if (sock->type == SOCK_STREAM)
+		sock->ops = &caif_stream_ops;
+	else
+		return -ESOCKTNOSUPPORT;
+
+	if (protocol < 0 || protocol >= CAIFPROTO_MAX)
+		return -EPROTONOSUPPORT;
+	/*
+	 * Set the socket state to unconnected.	 The socket state
+	 * is really not used at all in the net/core or socket.c but the
+	 * initialization makes sure that sock->state is not uninitialized.
+	 */
+	sk = sk_alloc(net, PF_CAIF, GFP_KERNEL, &prot, kern);
+	if (!sk)
+		return -ENOMEM;
+
+	cf_sk = container_of(sk, struct caifsock, sk);
+
+	/* Store the protocol */
+	sk->sk_protocol = (unsigned char) protocol;
+
+	/* Initialize default priority for well-known cases */
+	switch (protocol) {
+	case CAIFPROTO_AT:
+		sk->sk_priority = TC_PRIO_CONTROL;
+		break;
+	case CAIFPROTO_RFM:
+		sk->sk_priority = TC_PRIO_INTERACTIVE_BULK;
+		break;
+	default:
+		sk->sk_priority = TC_PRIO_BESTEFFORT;
+	}
+
+	/*
+	 * Lock in order to try to stop someone from opening the socket
+	 * too early.
+	 */
+	lock_sock(&(cf_sk->sk));
+
+	/* Initialize the nozero default sock structure data. */
+	sock_init_data(sock, sk);
+	sk->sk_destruct = caif_sock_destructor;
+
+	mutex_init(&cf_sk->readlock); /* single task reading lock */
+	cf_sk->layer.ctrlcmd = caif_ctrl_cb;
+	cf_sk->sk.sk_socket->state = SS_UNCONNECTED;
+	cf_sk->sk.sk_state = CAIF_DISCONNECTED;
+
+	set_tx_flow_off(cf_sk);
+	set_rx_flow_on(cf_sk);
+
+	/* Set default options on configuration */
+	cf_sk->conn_req.link_selector = CAIF_LINK_LOW_LATENCY;
+	cf_sk->conn_req.protocol = protocol;
+	release_sock(&cf_sk->sk);
+	return 0;
+}
+
+
+static struct net_proto_family caif_family_ops = {
+	.family = PF_CAIF,
+	.create = caif_create,
+	.owner = THIS_MODULE,
+};
+
+static int __init caif_sktinit_module(void)
+{
+	int err = sock_register(&caif_family_ops);
+	if (!err)
+		return err;
+	return 0;
+}
+
+static void __exit caif_sktexit_module(void)
+{
+	sock_unregister(PF_CAIF);
+}
+module_init(caif_sktinit_module);
+module_exit(caif_sktexit_module);