[v3,2/5] soc: qcom: Introduce QMI helpers

diff --git a/drivers/soc/qcom/Kconfig b/drivers/soc/qcom/Kconfig
index 91b70b170a82..9718f1c41e3d 100644
--- a/drivers/soc/qcom/Kconfig
+++ b/drivers/soc/qcom/Kconfig
@@ -37,6 +37,7 @@  config QCOM_PM
 
 config QCOM_QMI_HELPERS
 	tristate
+	depends on ARCH_QCOM
 	help
 	  Helper library for handling QMI encoded messages.  QMI encoded
 	  messages are used in communication between the majority of QRTR
diff --git a/drivers/soc/qcom/Makefile b/drivers/soc/qcom/Makefile
index 625750acfeef..b04b5044775f 100644
--- a/drivers/soc/qcom/Makefile
+++ b/drivers/soc/qcom/Makefile
@@ -4,6 +4,7 @@  obj-$(CONFIG_QCOM_MDT_LOADER)	+= mdt_loader.o
 obj-$(CONFIG_QCOM_PM)	+=	spm.o
 obj-$(CONFIG_QCOM_QMI_HELPERS)	+= qmi_helpers.o
 qmi_helpers-y	+= qmi_encdec.o
+qmi_helpers-y	+= qmi_interface.o
 obj-$(CONFIG_QCOM_SMD_RPM)	+= smd-rpm.o
 obj-$(CONFIG_QCOM_SMEM) +=	smem.o
 obj-$(CONFIG_QCOM_SMEM_STATE) += smem_state.o
diff --git a/drivers/soc/qcom/qmi_interface.c b/drivers/soc/qcom/qmi_interface.c
new file mode 100644
index 000000000000..6651257f15a4
--- /dev/null
+++ b/drivers/soc/qcom/qmi_interface.c
@@ -0,0 +1,849 @@ 
+/*
+ * Copyright (C) 2017 Linaro Ltd.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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/kernel.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/platform_device.h>
+#include <linux/qrtr.h>
+#include <linux/net.h>
+#include <linux/completion.h>
+#include <linux/idr.h>
+#include <linux/string.h>
+#include <net/sock.h>
+#include <linux/workqueue.h>
+#include <linux/soc/qcom/qmi.h>
+
+static struct socket *qmi_sock_create(struct qmi_handle *qmi,
+				      struct sockaddr_qrtr *sq);
+
+/**
+ * qmi_recv_new_server() - handler of NEW_SERVER control message
+ * @qmi:	qmi handle
+ * @node:	node of the new server
+ * @port:	port of the new server
+ *
+ * Calls the new_server callback to inform the client about a newly registered
+ * server matching the currently registered service lookup.
+ */
+static void qmi_recv_new_server(struct qmi_handle *qmi,
+				unsigned int service, unsigned int instance,
+				unsigned int node, unsigned int port)
+{
+	struct qmi_ops *ops = &qmi->ops;
+	struct qmi_service *svc;
+	int ret;
+
+	if (!ops->new_server)
+		return;
+
+	/* Ignore EOF marker */
+	if (!node && !port)
+		return;
+
+	svc = kzalloc(sizeof(*svc), GFP_KERNEL);
+	if (!svc)
+		return;
+
+	svc->service = service;
+	svc->version = instance & 0xff;
+	svc->instance = instance >> 8;
+	svc->node = node;
+	svc->port = port;
+
+	ret = ops->new_server(qmi, svc);
+	if (ret < 0)
+		kfree(svc);
+	else
+		list_add(&svc->list_node, &qmi->lookup_results);
+}
+
+/**
+ * qmi_recv_del_server() - handler of DEL_SERVER control message
+ * @qmi:	qmi handle
+ * @node:	node of the dying server, a value of -1 matches all nodes
+ * @port:	port of the dying server, a value of -1 matches all ports
+ *
+ * Calls the del_server callback for each previously seen server, allowing the
+ * client to react to the disappearing server.
+ */
+static void qmi_recv_del_server(struct qmi_handle *qmi,
+				unsigned int node, unsigned int port)
+{
+	struct qmi_ops *ops = &qmi->ops;
+	struct qmi_service *svc;
+	struct qmi_service *tmp;
+
+	list_for_each_entry_safe(svc, tmp, &qmi->lookup_results, list_node) {
+		if (node != -1 && svc->node != node)
+			continue;
+		if (port != -1 && svc->port != port)
+			continue;
+
+		if (ops->del_server)
+			ops->del_server(qmi, svc);
+
+		list_del(&svc->list_node);
+		kfree(svc);
+	}
+}
+
+/**
+ * qmi_recv_bye() - handler of BYE control message
+ * @qmi:	qmi handle
+ * @node:	id of the dying node
+ *
+ * Signals the client that all previously registered services on this node are
+ * now gone and then calls the bye callback to allow the client client further
+ * cleaning up resources associated with this remote.
+ */
+static void qmi_recv_bye(struct qmi_handle *qmi,
+			 unsigned int node)
+{
+	struct qmi_ops *ops = &qmi->ops;
+
+	qmi_recv_del_server(qmi, node, -1);
+
+	if (ops->bye)
+		ops->bye(qmi, node);
+}
+
+/**
+ * qmi_recv_del_client() - handler of DEL_CLIENT control message
+ * @qmi:	qmi handle
+ * @node:	node of the dying client
+ * @port:	port of the dying client
+ *
+ * Signals the client about a dying client, by calling the del_client callback.
+ */
+static void qmi_recv_del_client(struct qmi_handle *qmi,
+				unsigned int node, unsigned int port)
+{
+	struct qmi_ops *ops = &qmi->ops;
+
+	if (ops->del_client)
+		ops->del_client(qmi, node, port);
+}
+
+static void qmi_recv_ctrl_pkt(struct qmi_handle *qmi,
+			      const void *buf, size_t len)
+{
+	const struct qrtr_ctrl_pkt *pkt = buf;
+
+	if (len < sizeof(struct qrtr_ctrl_pkt)) {
+		pr_debug("ignoring short control packet\n");
+		return;
+	}
+
+	switch (le32_to_cpu(pkt->cmd)) {
+	case QRTR_TYPE_BYE:
+		qmi_recv_bye(qmi, le32_to_cpu(pkt->client.node));
+		break;
+	case QRTR_TYPE_NEW_SERVER:
+		qmi_recv_new_server(qmi,
+				    le32_to_cpu(pkt->server.service),
+				    le32_to_cpu(pkt->server.instance),
+				    le32_to_cpu(pkt->server.node),
+				    le32_to_cpu(pkt->server.port));
+		break;
+	case QRTR_TYPE_DEL_SERVER:
+		qmi_recv_del_server(qmi,
+				    le32_to_cpu(pkt->server.node),
+				    le32_to_cpu(pkt->server.port));
+		break;
+	case QRTR_TYPE_DEL_CLIENT:
+		qmi_recv_del_client(qmi,
+				    le32_to_cpu(pkt->client.node),
+				    le32_to_cpu(pkt->client.port));
+		break;
+	}
+}
+
+static void qmi_send_new_lookup(struct qmi_handle *qmi, struct qmi_service *svc)
+{
+	struct qrtr_ctrl_pkt pkt;
+	struct sockaddr_qrtr sq;
+	struct msghdr msg = {0};
+	struct kvec iv = { &pkt, sizeof(pkt) };
+	int ret;
+
+	memset(&pkt, 0, sizeof(pkt));
+	pkt.cmd = cpu_to_le32(QRTR_TYPE_NEW_LOOKUP);
+	pkt.server.service = cpu_to_le32(svc->service);
+	pkt.server.instance = cpu_to_le32(svc->version | svc->instance << 8);
+
+	sq.sq_family = qmi->sq.sq_family;
+	sq.sq_node = qmi->sq.sq_node;
+	sq.sq_port = QRTR_PORT_CTRL;
+
+	msg.msg_name = &sq;
+	msg.msg_namelen = sizeof(sq);
+
+	mutex_lock(&qmi->sock_lock);
+	if (qmi->sock) {
+		ret = kernel_sendmsg(qmi->sock, &msg, &iv, 1, sizeof(pkt));
+		if (ret < 0)
+			pr_err("failed to send lookup registration: %d\n", ret);
+	}
+	mutex_unlock(&qmi->sock_lock);
+}
+
+/**
+ * qmi_add_lookup() - register a new lookup with the name service
+ * @qmi:	qmi handle
+ * @service:	service id of the request
+ * @instance:	instance id of the request
+ *
+ * Returns 0 on success, negative errno on failure.
+ *
+ * Registering a lookup query with the name server will cause the name server
+ * to send NEW_SERVER and DEL_SERVER control messages to this socket as
+ * matching services are registered.
+ */
+int qmi_add_lookup(struct qmi_handle *qmi, unsigned int service,
+		   unsigned int version, unsigned int instance)
+{
+	struct qmi_service *svc;
+
+	svc = kzalloc(sizeof(*svc), GFP_KERNEL);
+	if (!svc)
+		return -ENOMEM;
+
+	svc->service = service;
+	svc->version = version;
+	svc->instance = instance;
+
+	list_add(&svc->list_node, &qmi->lookups);
+
+	qmi_send_new_lookup(qmi, svc);
+
+	return 0;
+}
+EXPORT_SYMBOL(qmi_add_lookup);
+
+static void qmi_send_new_server(struct qmi_handle *qmi, struct qmi_service *svc)
+{
+	struct qrtr_ctrl_pkt pkt;
+	struct sockaddr_qrtr sq;
+	struct msghdr msg = {0};
+	struct kvec iv = { &pkt, sizeof(pkt) };
+	int ret;
+
+	memset(&pkt, 0, sizeof(pkt));
+	pkt.cmd = cpu_to_le32(QRTR_TYPE_NEW_SERVER);
+	pkt.server.service = cpu_to_le32(svc->service);
+	pkt.server.instance = cpu_to_le32(svc->version | svc->instance << 8);
+	pkt.server.node = qmi->sq.sq_node;
+	pkt.server.port = qmi->sq.sq_port;
+
+	sq.sq_family = qmi->sq.sq_family;
+	sq.sq_node = qmi->sq.sq_node;
+	sq.sq_port = QRTR_PORT_CTRL;
+
+	msg.msg_name = &sq;
+	msg.msg_namelen = sizeof(sq);
+
+	mutex_lock(&qmi->sock_lock);
+	if (qmi->sock) {
+		ret = kernel_sendmsg(qmi->sock, &msg, &iv, 1, sizeof(pkt));
+		if (ret < 0)
+			pr_err("send service registration failed: %d\n", ret);
+	}
+	mutex_unlock(&qmi->sock_lock);
+}
+
+/**
+ * qmi_add_server() - register a service with the name service
+ * @qmi:	qmi handle
+ * @service:	type of the service
+ * @instance:	instance of the service
+ *
+ * Returns 0 on success, negative errno on failure.
+ *
+ * Register a new service with the name service. This allows clients to find
+ * and start sending messages to the client associated with @qmi.
+ */
+int qmi_add_server(struct qmi_handle *qmi, unsigned int service,
+		   unsigned int version, unsigned int instance)
+{
+	struct qmi_service *svc;
+
+	svc = kzalloc(sizeof(*svc), GFP_KERNEL);
+	if (!svc)
+		return -ENOMEM;
+
+	svc->service = service;
+	svc->version = version;
+	svc->instance = instance;
+
+	list_add(&svc->list_node, &qmi->services);
+
+	qmi_send_new_server(qmi, svc);
+
+	return 0;
+}
+EXPORT_SYMBOL(qmi_add_server);
+
+/**
+ * qmi_txn_init() - allocate transaction id within the given QMI handle
+ * @qmi:	QMI handle
+ * @txn:	transaction context
+ * @ei:		description of how to decode a matching response (optional)
+ * @c_struct:	pointer to the object to decode the response into (optional)
+ *
+ * Returns transaction id on success, negative errno on failure.
+ *
+ * This allocates a transaction id within the QMI handle. If @ei and @c_struct
+ * are specified any responses to this transaction will be decoded as described
+ * by @ei into @c_struct.
+ *
+ * A client calling qmi_txn_init() must call either qmi_txn_wait() or
+ * qmi_txn_cancel() to free up the allocated resources.
+ */
+int qmi_txn_init(struct qmi_handle *qmi, struct qmi_txn *txn,
+		 struct qmi_elem_info *ei, void *c_struct)
+{
+	int ret;
+
+	memset(txn, 0, sizeof(*txn));
+
+	mutex_init(&txn->lock);
+	init_completion(&txn->completion);
+	txn->qmi = qmi;
+	txn->ei = ei;
+	txn->dest = c_struct;
+
+	mutex_lock(&qmi->txn_lock);
+	ret = idr_alloc_cyclic(&qmi->txns, txn, 0, INT_MAX, GFP_KERNEL);
+	if (ret < 0)
+		pr_err("failed to allocate transaction id\n");
+
+	txn->id = ret;
+	mutex_unlock(&qmi->txn_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(qmi_txn_init);
+
+/**
+ * qmi_txn_wait() - wait for a response on a transaction
+ * @txn:	transaction handle
+ * @timeout:	timeout, in jiffies
+ *
+ * Returns the transaction response on success, negative errno on failure.
+ *
+ * If the transaction is decoded by the means of @ei and @c_struct the return
+ * value will be the returned value of qmi_decode_message(), otherwise it's up
+ * to the specified message handler to fill out the result.
+ */
+int qmi_txn_wait(struct qmi_txn *txn, unsigned long timeout)
+{
+	struct qmi_handle *qmi = txn->qmi;
+	int ret;
+
+	ret = wait_for_completion_interruptible_timeout(&txn->completion,
+							timeout);
+
+	mutex_lock(&qmi->txn_lock);
+	mutex_lock(&txn->lock);
+	idr_remove(&qmi->txns, txn->id);
+	mutex_unlock(&txn->lock);
+	mutex_unlock(&qmi->txn_lock);
+
+	if (ret < 0)
+		return ret;
+	else if (ret == 0)
+		return -ETIMEDOUT;
+	else
+		return txn->result;
+}
+EXPORT_SYMBOL(qmi_txn_wait);
+
+/**
+ * qmi_txn_cancel() - cancel an ongoing transaction
+ * @txn:	transaction id
+ */
+void qmi_txn_cancel(struct qmi_txn *txn)
+{
+	struct qmi_handle *qmi = txn->qmi;
+
+	mutex_lock(&qmi->txn_lock);
+	mutex_lock(&txn->lock);
+	idr_remove(&qmi->txns, txn->id);
+	mutex_unlock(&txn->lock);
+	mutex_unlock(&qmi->txn_lock);
+}
+EXPORT_SYMBOL(qmi_txn_cancel);
+
+/**
+ * qmi_invoke_handler() - find and invoke a handler for a message
+ * @qmi:	qmi handle
+ * @sq:		sockaddr of the sender
+ * @txn:	transaction object for the message
+ * @buf:	buffer containing the message
+ * @len:	length of @buf
+ *
+ * Find handler and invoke handler for the incoming message.
+ */
+static void qmi_invoke_handler(struct qmi_handle *qmi, struct sockaddr_qrtr *sq,
+			       struct qmi_txn *txn, const void *buf, size_t len)
+{
+	struct qmi_msg_handler *handler;
+	const struct qmi_header *hdr = buf;
+	void *dest;
+	int ret;
+
+	if (!qmi->handlers)
+		return;
+
+	for (handler = qmi->handlers; handler->fn; handler++) {
+		if (handler->type == hdr->type &&
+		    handler->msg_id == hdr->msg_id)
+			break;
+	}
+
+	if (!handler->fn)
+		return;
+
+	dest = kzalloc(handler->decoded_size, GFP_KERNEL);
+	if (!dest)
+		return;
+
+	ret = qmi_decode_message(buf, len, handler->ei, dest);
+	if (ret < 0)
+		pr_err("failed to decode incoming message\n");
+	else
+		handler->fn(qmi, sq, txn, dest);
+
+	kfree(dest);
+}
+
+/**
+ * qmi_handle_net_reset() - invoked to handle ENETRESET on a QMI handle
+ * @qmi:	the QMI context
+ *
+ * As a result of registering a name service with the QRTR all open sockets are
+ * flagged with ENETRESET and this function will be called. The typical case is
+ * the initial boot, where this signals that the local node id has been
+ * configured and as such any bound sockets needs to be rebound. So close the
+ * socket, inform the client and re-initialize the socket.
+ *
+ * For clients it's generally sufficient to react to the del_server callbacks,
+ * but server code is expected to treat the net_reset callback as a "bye" from
+ * all nodes.
+ *
+ * Finally the QMI handle will send out registration requests for any lookups
+ * and services.
+ */
+static void qmi_handle_net_reset(struct qmi_handle *qmi)
+{
+	struct sockaddr_qrtr sq;
+	struct qmi_service *svc;
+	struct socket *sock;
+
+	sock = qmi_sock_create(qmi, &sq);
+	if (IS_ERR(sock))
+		return;
+
+	mutex_lock(&qmi->sock_lock);
+	sock_release(qmi->sock);
+	qmi->sock = NULL;
+	mutex_unlock(&qmi->sock_lock);
+
+	qmi_recv_del_server(qmi, -1, -1);
+
+	if (qmi->ops.net_reset)
+		qmi->ops.net_reset(qmi);
+
+	mutex_lock(&qmi->sock_lock);
+	qmi->sock = sock;
+	qmi->sq = sq;
+	mutex_unlock(&qmi->sock_lock);
+
+	list_for_each_entry(svc, &qmi->lookups, list_node)
+		qmi_send_new_lookup(qmi, svc);
+
+	list_for_each_entry(svc, &qmi->services, list_node)
+		qmi_send_new_server(qmi, svc);
+}
+
+static void qmi_handle_message(struct qmi_handle *qmi,
+			       struct sockaddr_qrtr *sq,
+			       const void *buf, size_t len)
+{
+	const struct qmi_header *hdr;
+	struct qmi_txn tmp_txn;
+	struct qmi_txn *txn = NULL;
+	int ret;
+
+	if (len < sizeof(*hdr)) {
+		pr_err("ignoring short QMI packet\n");
+		return;
+	}
+
+	hdr = buf;
+
+	/* If this is a response, find the matching transaction handle */
+	if (hdr->type == QMI_RESPONSE) {
+		mutex_lock(&qmi->txn_lock);
+		txn = idr_find(&qmi->txns, hdr->txn_id);
+		if (txn)
+			mutex_lock(&txn->lock);
+		mutex_unlock(&qmi->txn_lock);
+	}
+
+	if (txn && txn->dest && txn->ei) {
+		ret = qmi_decode_message(buf, len, txn->ei, txn->dest);
+		if (ret < 0)
+			pr_err("failed to decode incoming message\n");
+
+		txn->result = ret;
+		complete(&txn->completion);
+
+		mutex_unlock(&txn->lock);
+	} else if (txn) {
+		qmi_invoke_handler(qmi, sq, txn, buf, len);
+
+		mutex_unlock(&txn->lock);
+	} else {
+		/* Create a txn based on the txn_id of the incoming message */
+		memset(&tmp_txn, 0, sizeof(tmp_txn));
+		tmp_txn.id = hdr->txn_id;
+
+		qmi_invoke_handler(qmi, sq, &tmp_txn, buf, len);
+	}
+}
+
+static void qmi_data_ready_work(struct work_struct *work)
+{
+	struct qmi_handle *qmi = container_of(work, struct qmi_handle, work);
+	struct qmi_ops *ops = &qmi->ops;
+	struct sockaddr_qrtr sq;
+	struct msghdr msg = { .msg_name = &sq, .msg_namelen = sizeof(sq) };
+	struct kvec iv;
+	ssize_t msglen;
+
+	for (;;) {
+		iv.iov_base = qmi->recv_buf;
+		iv.iov_len = qmi->recv_buf_size;
+
+		mutex_lock(&qmi->sock_lock);
+		if (qmi->sock)
+			msglen = kernel_recvmsg(qmi->sock, &msg, &iv, 1,
+						iv.iov_len, MSG_DONTWAIT);
+		else
+			msglen = -EPIPE;
+		mutex_unlock(&qmi->sock_lock);
+		if (msglen == -EAGAIN)
+			break;
+
+		if (msglen == -ENETRESET) {
+			qmi_handle_net_reset(qmi);
+
+			/* The old qmi->sock is gone, our work is done */
+			break;
+		}
+
+		if (msglen < 0) {
+			pr_err("qmi recvmsg failed: %zd\n", msglen);
+			break;
+		}
+
+		if (sq.sq_node == qmi->sq.sq_node &&
+		    sq.sq_port == QRTR_PORT_CTRL) {
+			qmi_recv_ctrl_pkt(qmi, qmi->recv_buf, msglen);
+		} else if (ops->msg_handler) {
+			ops->msg_handler(qmi, &sq, qmi->recv_buf, msglen);
+		} else {
+			qmi_handle_message(qmi, &sq, qmi->recv_buf, msglen);
+		}
+	}
+}
+
+static void qmi_data_ready(struct sock *sk)
+{
+	struct qmi_handle *qmi = sk->sk_user_data;
+
+	/*
+	 * This will be NULL if we receive data while being in
+	 * qmi_handle_release()
+	 */
+	if (!qmi)
+		return;
+
+	queue_work(qmi->wq, &qmi->work);
+}
+
+static struct socket *qmi_sock_create(struct qmi_handle *qmi,
+				      struct sockaddr_qrtr *sq)
+{
+	struct socket *sock;
+	int sl = sizeof(*sq);
+	int ret;
+
+	ret = sock_create_kern(&init_net, AF_QIPCRTR, SOCK_DGRAM,
+			       PF_QIPCRTR, &sock);
+	if (ret < 0)
+		return ERR_PTR(ret);
+
+	ret = kernel_getsockname(sock, (struct sockaddr *)sq, &sl);
+	if (ret < 0) {
+		sock_release(sock);
+		return ERR_PTR(ret);
+	}
+
+	sock->sk->sk_user_data = qmi;
+	sock->sk->sk_data_ready = qmi_data_ready;
+	sock->sk->sk_error_report = qmi_data_ready;
+
+	return sock;
+}
+
+/**
+ * qmi_handle_init() - initialize a QMI client handle
+ * @qmi:	QMI handle to initialize
+ * @max_msg_len: maximum size of incoming message
+ * @handlers:	NULL-terminated list of QMI message handlers
+ *
+ * Returns 0 on success, negative errno on failure.
+ *
+ * This initializes the QMI client handle to allow sending and receiving QMI
+ * messages. As messages are received the appropriate handler will be invoked.
+ */
+int qmi_handle_init(struct qmi_handle *qmi, size_t recv_buf_size,
+		    struct qmi_ops *ops, struct qmi_msg_handler *handlers)
+{
+	int ret;
+
+	mutex_init(&qmi->txn_lock);
+	mutex_init(&qmi->sock_lock);
+
+	idr_init(&qmi->txns);
+
+	INIT_LIST_HEAD(&qmi->lookups);
+	INIT_LIST_HEAD(&qmi->lookup_results);
+	INIT_LIST_HEAD(&qmi->services);
+
+	INIT_WORK(&qmi->work, qmi_data_ready_work);
+
+	qmi->handlers = handlers;
+	if (ops)
+		qmi->ops = *ops;
+
+	if (recv_buf_size < sizeof(struct qrtr_ctrl_pkt))
+		recv_buf_size = sizeof(struct qrtr_ctrl_pkt);
+	else
+		recv_buf_size += sizeof(struct qmi_header);
+
+	qmi->recv_buf_size = recv_buf_size;
+	qmi->recv_buf = kzalloc(recv_buf_size, GFP_KERNEL);
+	if (!qmi->recv_buf)
+		return -ENOMEM;
+
+	qmi->wq = alloc_workqueue("qmi_msg_handler", WQ_UNBOUND, 1);
+	if (!qmi->wq) {
+		ret = -ENOMEM;
+		goto err_free_recv_buf;
+	}
+
+	qmi->sock = qmi_sock_create(qmi, &qmi->sq);
+	if (IS_ERR(qmi->sock)) {
+		pr_err("failed to create QMI socket\n");
+		ret = PTR_ERR(qmi->sock);
+		goto err_destroy_wq;
+	}
+
+	return 0;
+
+err_destroy_wq:
+	destroy_workqueue(qmi->wq);
+err_free_recv_buf:
+	kfree(qmi->recv_buf);
+
+	return ret;
+}
+EXPORT_SYMBOL(qmi_handle_init);
+
+/**
+ * qmi_handle_release() - release the QMI client handle
+ * @qmi:	QMI client handle
+ *
+ * This closes the underlying socket and stops any handling of QMI messages.
+ */
+void qmi_handle_release(struct qmi_handle *qmi)
+{
+	struct socket *sock = qmi->sock;
+	struct qmi_service *svc, *tmp;
+
+	sock->sk->sk_user_data = NULL;
+	cancel_work_sync(&qmi->work);
+
+	qmi_recv_del_server(qmi, -1, -1);
+
+	mutex_lock(&qmi->sock_lock);
+	sock_release(sock);
+	qmi->sock = NULL;
+	mutex_unlock(&qmi->sock_lock);
+
+	destroy_workqueue(qmi->wq);
+
+	idr_destroy(&qmi->txns);
+
+	kfree(qmi->recv_buf);
+
+	/* Free registered lookup requests */
+	list_for_each_entry_safe(svc, tmp, &qmi->lookups, list_node) {
+		list_del(&svc->list_node);
+		kfree(svc);
+	}
+
+	/* Free registered service information */
+	list_for_each_entry_safe(svc, tmp, &qmi->services, list_node) {
+		list_del(&svc->list_node);
+		kfree(svc);
+	}
+}
+EXPORT_SYMBOL(qmi_handle_release);
+
+/**
+ * qmi_send_message() - send a QMI message
+ * @qmi:	QMI client handle
+ * @sq:		destination sockaddr
+ * @txn:	transaction object to use for the message
+ * @type:	type of message to send
+ * @msg_id:	message id
+ * @len:	max length of the QMI message
+ * @ei:		QMI message description
+ * @c_struct:	object to be encoded
+ *
+ * Returns 0 on success, negative errno on failure.
+ *
+ * This function encodes @c_struct using @ei into a message of type @type,
+ * with @msg_id and @txn into a buffer of maximum size @len, and sends this to
+ * @sq.
+ */
+static ssize_t qmi_send_message(struct qmi_handle *qmi,
+				struct sockaddr_qrtr *sq, struct qmi_txn *txn,
+				int type, int msg_id, size_t len,
+				struct qmi_elem_info *ei, const void *c_struct)
+{
+	struct msghdr msghdr = {0};
+	struct kvec iv;
+	void *msg;
+	int ret;
+
+	msg = qmi_encode_message(type,
+				 msg_id, &len,
+				 txn->id, ei,
+				 c_struct);
+	if (IS_ERR(msg))
+		return PTR_ERR(msg);
+
+	iv.iov_base = msg;
+	iv.iov_len = len;
+
+	if (sq) {
+		msghdr.msg_name = sq;
+		msghdr.msg_namelen = sizeof(*sq);
+	}
+
+	mutex_lock(&qmi->sock_lock);
+	if (qmi->sock) {
+		ret = kernel_sendmsg(qmi->sock, &msghdr, &iv, 1, len);
+		if (ret < 0)
+			pr_err("failed to send QMI message\n");
+	} else {
+		ret = -EPIPE;
+	}
+	mutex_unlock(&qmi->sock_lock);
+
+	kfree(msg);
+
+	return ret < 0 ? ret : 0;
+}
+
+/**
+ * qmi_send_request() - send a request QMI message
+ * @qmi:	QMI client handle
+ * @sq:		destination sockaddr
+ * @txn:	transaction object to use for the message
+ * @msg_id:	message id
+ * @len:	max length of the QMI message
+ * @ei:		QMI message description
+ * @c_struct:	object to be encoded
+ *
+ * Returns 0 on success, negative errno on failure.
+ */
+ssize_t qmi_send_request(struct qmi_handle *qmi, struct sockaddr_qrtr *sq,
+			 struct qmi_txn *txn, int msg_id, size_t len,
+			 struct qmi_elem_info *ei, const void *c_struct)
+{
+	return qmi_send_message(qmi, sq, txn, QMI_REQUEST, msg_id, len, ei,
+				c_struct);
+}
+EXPORT_SYMBOL(qmi_send_request);
+
+/**
+ * qmi_send_response() - send a response QMI message
+ * @qmi:	QMI client handle
+ * @sq:		destination sockaddr
+ * @txn:	transaction object to use for the message
+ * @msg_id:	message id
+ * @len:	max length of the QMI message
+ * @ei:		QMI message description
+ * @c_struct:	object to be encoded
+ *
+ * Returns 0 on success, negative errno on failure.
+ */
+ssize_t qmi_send_response(struct qmi_handle *qmi, struct sockaddr_qrtr *sq,
+			  struct qmi_txn *txn, int msg_id, size_t len,
+			  struct qmi_elem_info *ei, const void *c_struct)
+{
+	return qmi_send_message(qmi, sq, txn, QMI_RESPONSE, msg_id, len, ei,
+				c_struct);
+}
+EXPORT_SYMBOL(qmi_send_response);
+
+/**
+ * qmi_send_indication() - send an indication QMI message
+ * @qmi:	QMI client handle
+ * @sq:		destination sockaddr
+ * @txn:	transaction object to use for the message
+ * @msg_id:	message id
+ * @len:	max length of the QMI message
+ * @ei:		QMI message description
+ * @c_struct:	object to be encoded
+ *
+ * Returns 0 on success, negative errno on failure.
+ */
+ssize_t qmi_send_indication(struct qmi_handle *qmi, struct sockaddr_qrtr *sq,
+			    int msg_id, size_t len, struct qmi_elem_info *ei,
+			    const void *c_struct)
+{
+	struct qmi_txn txn;
+	ssize_t rval;
+	int ret;
+
+	ret = qmi_txn_init(qmi, &txn, NULL, NULL);
+	if (ret < 0)
+		return ret;
+
+	rval = qmi_send_message(qmi, sq, &txn, QMI_INDICATION, msg_id, len, ei,
+				c_struct);
+
+	/* We don't care about future messages on this txn */
+	qmi_txn_cancel(&txn);
+
+	return rval;
+}
+EXPORT_SYMBOL(qmi_send_indication);
diff --git a/include/linux/soc/qcom/qmi.h b/include/linux/soc/qcom/qmi.h
index 5df7edfc6bfd..9b4f4fa5bed6 100644
--- a/include/linux/soc/qcom/qmi.h
+++ b/include/linux/soc/qcom/qmi.h
@@ -105,6 +105,158 @@  struct qmi_response_type_v01 {
 
 extern struct qmi_elem_info qmi_response_type_v01_ei[];
 
+/**
+ * struct qmi_service - context to track lookup-results
+ * @service:	service type
+ * @version:	version of the @service
+ * @instance:	instance id of the @service
+ * @node:	node of the service
+ * @port:	port of the service
+ * @priv:	handle for client's use
+ * @list_node:	list_head for house keeping
+ */
+struct qmi_service {
+	unsigned int service;
+	unsigned int version;
+	unsigned int instance;
+
+	unsigned int node;
+	unsigned int port;
+
+	void *priv;
+	struct list_head list_node;
+};
+
+struct qmi_handle;
+
+/**
+ * struct qmi_ops - callbacks for qmi_handle
+ * @new_server:		inform client of a new_server lookup-result, returning
+ *                      successfully from this call causes the library to call
+ *                      @del_server as the service is removed from the
+ *                      lookup-result. @priv of the qmi_service can be used by
+ *                      the client
+ * @del_server:		inform client of a del_server lookup-result
+ * @net_reset:		inform client that the name service was restarted and
+ *                      that and any state needs to be released
+ * @msg_handler:	invoked for incoming messages, allows a client to
+ *                      override the usual QMI message handler
+ * @bye:                inform a client that all clients from a node are gone
+ * @del_client:         inform a client that a particular client is gone
+ */
+struct qmi_ops {
+	int (*new_server)(struct qmi_handle *qmi, struct qmi_service *svc);
+	void (*del_server)(struct qmi_handle *qmi, struct qmi_service *svc);
+	void (*net_reset)(struct qmi_handle *qmi);
+	void (*msg_handler)(struct qmi_handle *qmi, struct sockaddr_qrtr *sq,
+			    const void *data, size_t count);
+	void (*bye)(struct qmi_handle *qmi, unsigned int node);
+	void (*del_client)(struct qmi_handle *qmi,
+			   unsigned int node, unsigned int port);
+};
+
+/**
+ * struct qmi_txn - transaction context
+ * @qmi:	QMI handle this transaction is associated with
+ * @id:		transaction id
+ * @lock:	for synchronization between handler and waiter of messages
+ * @completion:	completion object as the transaction receives a response
+ * @result:	result code for the completed transaction
+ * @ei:		description of the QMI encoded response (optional)
+ * @dest:	destination buffer to decode message into (optional)
+ */
+struct qmi_txn {
+	struct qmi_handle *qmi;
+
+	int id;
+
+	struct mutex lock;
+	struct completion completion;
+	int result;
+
+	struct qmi_elem_info *ei;
+	void *dest;
+};
+
+/**
+ * struct qmi_msg_handler - description of QMI message handler
+ * @type:	type of message
+ * @msg_id:	message id
+ * @ei:		description of the QMI encoded message
+ * @decoded_size:	size of the decoded object
+ * @fn:		function to invoke as the message is decoded
+ */
+struct qmi_msg_handler {
+	unsigned int type;
+	unsigned int msg_id;
+
+	struct qmi_elem_info *ei;
+
+	size_t decoded_size;
+	void (*fn)(struct qmi_handle *qmi, struct sockaddr_qrtr *sq,
+		   struct qmi_txn *txn, const void *decoded);
+};
+
+/**
+ * struct qmi_handle - QMI context
+ * @sock:	socket handle
+ * @sock_lock:	synchronization of @sock modifications
+ * @sq:		sockaddr of @sock
+ * @work:	work for handling incoming messages
+ * @wq:		workqueue to post @work on
+ * @recv_buf:	scratch buffer for handling incoming messages
+ * @recv_buf_size:	size of @recv_buf
+ * @lookups:		list of registered lookup requests
+ * @lookup_results:	list of lookup-results advertised to the client
+ * @services:		list of registered services (by this client)
+ * @ops:	reference to callbacks
+ * @txns:	outstanding transactions
+ * @txn_lock:	lock for modifications of @txns
+ * @handlers:	list of handlers for incoming messages
+ */
+struct qmi_handle {
+	struct socket *sock;
+	struct mutex sock_lock;
+
+	struct sockaddr_qrtr sq;
+
+	struct work_struct work;
+	struct workqueue_struct *wq;
+
+	void *recv_buf;
+	size_t recv_buf_size;
+
+	struct list_head lookups;
+	struct list_head lookup_results;
+	struct list_head services;
+
+	struct qmi_ops ops;
+
+	struct idr txns;
+	struct mutex txn_lock;
+
+	struct qmi_msg_handler *handlers;
+};
+
+int qmi_add_lookup(struct qmi_handle *qmi, unsigned int service,
+		   unsigned int version, unsigned int instance);
+int qmi_add_server(struct qmi_handle *qmi, unsigned int service,
+		   unsigned int version, unsigned int instance);
+
+int qmi_handle_init(struct qmi_handle *qmi, size_t max_msg_len,
+		    struct qmi_ops *ops, struct qmi_msg_handler *handlers);
+void qmi_handle_release(struct qmi_handle *qmi);
+
+ssize_t qmi_send_request(struct qmi_handle *qmi, struct sockaddr_qrtr *sq,
+			 struct qmi_txn *txn, int msg_id, size_t len,
+			 struct qmi_elem_info *ei, const void *c_struct);
+ssize_t qmi_send_response(struct qmi_handle *qmi, struct sockaddr_qrtr *sq,
+			  struct qmi_txn *txn, int msg_id, size_t len,
+			  struct qmi_elem_info *ei, const void *c_struct);
+ssize_t qmi_send_indication(struct qmi_handle *qmi, struct sockaddr_qrtr *sq,
+			    int msg_id, size_t len, struct qmi_elem_info *ei,
+			    const void *c_struct);
+
 void *qmi_encode_message(int type, unsigned int msg_id, size_t *len,
 			 unsigned int txn_id, struct qmi_elem_info *ei,
 			 const void *c_struct);
@@ -112,4 +264,9 @@  void *qmi_encode_message(int type, unsigned int msg_id, size_t *len,
 int qmi_decode_message(const void *buf, size_t len,
 		       struct qmi_elem_info *ei, void *c_struct);
 
+int qmi_txn_init(struct qmi_handle *qmi, struct qmi_txn *txn,
+		 struct qmi_elem_info *ei, void *c_struct);
+int qmi_txn_wait(struct qmi_txn *txn, unsigned long timeout);
+void qmi_txn_cancel(struct qmi_txn *txn);
+
 #endif