6 files changed, 3777 insertions, 0 deletions

diff --git a/drivers/hsi/clients/Kconfig b/drivers/hsi/clients/Kconfig
new file mode 100644
index 000000000..80f60cb28
--- /dev/null
+++ b/drivers/hsi/clients/Kconfig
@@ -0,0 +1,41 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# HSI clients configuration
+#
+
+comment "HSI clients"
+
+config NOKIA_MODEM
+	tristate "Nokia Modem"
+	depends on HSI && SSI_PROTOCOL && CMT_SPEECH
+	help
+	Say Y here if you want to add support for the modem on Nokia
+	N900 (Nokia RX-51) hardware.
+
+	If unsure, say N.
+
+config CMT_SPEECH
+	tristate "CMT speech"
+	depends on HSI && SSI_PROTOCOL
+	help
+	If you say Y here, you will enable the CMT speech protocol used
+	by Nokia modems. If you say M the protocol will be available as
+	module named cmt_speech.
+
+	If unsure, say N.
+
+config SSI_PROTOCOL
+	tristate "SSI protocol"
+	depends on HSI && PHONET && OMAP_SSI
+	help
+	If you say Y here, you will enable the SSI protocol aka McSAAB.
+
+	If unsure, say N.
+
+config HSI_CHAR
+	tristate "HSI/SSI character driver"
+	depends on HSI
+	help
+	  If you say Y here, you will enable the HSI/SSI character driver.
+	  This driver provides a simple character device interface for
+	  serial communication with the cellular modem over HSI/SSI bus.
diff --git a/drivers/hsi/clients/Makefile b/drivers/hsi/clients/Makefile
new file mode 100644
index 000000000..8fab835fa
--- /dev/null
+++ b/drivers/hsi/clients/Makefile
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Makefile for HSI clients
+#
+
+obj-$(CONFIG_NOKIA_MODEM)	+= nokia-modem.o
+obj-$(CONFIG_SSI_PROTOCOL)	+= ssi_protocol.o
+obj-$(CONFIG_CMT_SPEECH)	+= cmt_speech.o
+obj-$(CONFIG_HSI_CHAR)		+= hsi_char.o
diff --git a/drivers/hsi/clients/cmt_speech.c b/drivers/hsi/clients/cmt_speech.c
new file mode 100644
index 000000000..8069f795c
--- /dev/null
+++ b/drivers/hsi/clients/cmt_speech.c
@@ -0,0 +1,1448 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * cmt_speech.c - HSI CMT speech driver
+ *
+ * Copyright (C) 2008,2009,2010 Nokia Corporation. All rights reserved.
+ *
+ * Contact: Kai Vehmanen <kai.vehmanen@nokia.com>
+ * Original author: Peter Ujfalusi <peter.ujfalusi@nokia.com>
+ */
+
+#include <linux/errno.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/miscdevice.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/poll.h>
+#include <linux/sched/signal.h>
+#include <linux/ioctl.h>
+#include <linux/uaccess.h>
+#include <linux/pm_qos.h>
+#include <linux/hsi/hsi.h>
+#include <linux/hsi/ssi_protocol.h>
+#include <linux/hsi/cs-protocol.h>
+
+#define CS_MMAP_SIZE	PAGE_SIZE
+
+struct char_queue {
+	struct list_head	list;
+	u32			msg;
+};
+
+struct cs_char {
+	unsigned int		opened;
+	struct hsi_client	*cl;
+	struct cs_hsi_iface	*hi;
+	struct list_head	chardev_queue;
+	struct list_head	dataind_queue;
+	int			dataind_pending;
+	/* mmap things */
+	unsigned long		mmap_base;
+	unsigned long		mmap_size;
+	spinlock_t		lock;
+	struct fasync_struct	*async_queue;
+	wait_queue_head_t	wait;
+	/* hsi channel ids */
+	int                     channel_id_cmd;
+	int                     channel_id_data;
+};
+
+#define SSI_CHANNEL_STATE_READING	1
+#define SSI_CHANNEL_STATE_WRITING	(1 << 1)
+#define SSI_CHANNEL_STATE_POLL		(1 << 2)
+#define SSI_CHANNEL_STATE_ERROR		(1 << 3)
+
+#define TARGET_MASK			0xf000000
+#define TARGET_REMOTE			(1 << CS_DOMAIN_SHIFT)
+#define TARGET_LOCAL			0
+
+/* Number of pre-allocated commands buffers */
+#define CS_MAX_CMDS		        4
+
+/*
+ * During data transfers, transactions must be handled
+ * within 20ms (fixed value in cmtspeech HSI protocol)
+ */
+#define CS_QOS_LATENCY_FOR_DATA_USEC	20000
+
+/* Timeout to wait for pending HSI transfers to complete */
+#define CS_HSI_TRANSFER_TIMEOUT_MS      500
+
+
+#define RX_PTR_BOUNDARY_SHIFT		8
+#define RX_PTR_MAX_SHIFT		(RX_PTR_BOUNDARY_SHIFT + \
+						CS_MAX_BUFFERS_SHIFT)
+struct cs_hsi_iface {
+	struct hsi_client		*cl;
+	struct hsi_client		*master;
+
+	unsigned int			iface_state;
+	unsigned int			wakeline_state;
+	unsigned int			control_state;
+	unsigned int			data_state;
+
+	/* state exposed to application */
+	struct cs_mmap_config_block	*mmap_cfg;
+
+	unsigned long			mmap_base;
+	unsigned long			mmap_size;
+
+	unsigned int			rx_slot;
+	unsigned int			tx_slot;
+
+	/* note: for security reasons, we do not trust the contents of
+	 * mmap_cfg, but instead duplicate the variables here */
+	unsigned int			buf_size;
+	unsigned int			rx_bufs;
+	unsigned int			tx_bufs;
+	unsigned int			rx_ptr_boundary;
+	unsigned int			rx_offsets[CS_MAX_BUFFERS];
+	unsigned int			tx_offsets[CS_MAX_BUFFERS];
+
+	/* size of aligned memory blocks */
+	unsigned int			slot_size;
+	unsigned int			flags;
+
+	struct list_head		cmdqueue;
+
+	struct hsi_msg			*data_rx_msg;
+	struct hsi_msg			*data_tx_msg;
+	wait_queue_head_t		datawait;
+
+	struct pm_qos_request           pm_qos_req;
+
+	spinlock_t			lock;
+};
+
+static struct cs_char cs_char_data;
+
+static void cs_hsi_read_on_control(struct cs_hsi_iface *hi);
+static void cs_hsi_read_on_data(struct cs_hsi_iface *hi);
+
+static inline void rx_ptr_shift_too_big(void)
+{
+	BUILD_BUG_ON((1LLU << RX_PTR_MAX_SHIFT) > UINT_MAX);
+}
+
+static void cs_notify(u32 message, struct list_head *head)
+{
+	struct char_queue *entry;
+
+	spin_lock(&cs_char_data.lock);
+
+	if (!cs_char_data.opened) {
+		spin_unlock(&cs_char_data.lock);
+		goto out;
+	}
+
+	entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
+	if (!entry) {
+		dev_err(&cs_char_data.cl->device,
+			"Can't allocate new entry for the queue.\n");
+		spin_unlock(&cs_char_data.lock);
+		goto out;
+	}
+
+	entry->msg = message;
+	list_add_tail(&entry->list, head);
+
+	spin_unlock(&cs_char_data.lock);
+
+	wake_up_interruptible(&cs_char_data.wait);
+	kill_fasync(&cs_char_data.async_queue, SIGIO, POLL_IN);
+
+out:
+	return;
+}
+
+static u32 cs_pop_entry(struct list_head *head)
+{
+	struct char_queue *entry;
+	u32 data;
+
+	entry = list_entry(head->next, struct char_queue, list);
+	data = entry->msg;
+	list_del(&entry->list);
+	kfree(entry);
+
+	return data;
+}
+
+static void cs_notify_control(u32 message)
+{
+	cs_notify(message, &cs_char_data.chardev_queue);
+}
+
+static void cs_notify_data(u32 message, int maxlength)
+{
+	cs_notify(message, &cs_char_data.dataind_queue);
+
+	spin_lock(&cs_char_data.lock);
+	cs_char_data.dataind_pending++;
+	while (cs_char_data.dataind_pending > maxlength &&
+				!list_empty(&cs_char_data.dataind_queue)) {
+		dev_dbg(&cs_char_data.cl->device, "data notification "
+		"queue overrun (%u entries)\n", cs_char_data.dataind_pending);
+
+		cs_pop_entry(&cs_char_data.dataind_queue);
+		cs_char_data.dataind_pending--;
+	}
+	spin_unlock(&cs_char_data.lock);
+}
+
+static inline void cs_set_cmd(struct hsi_msg *msg, u32 cmd)
+{
+	u32 *data = sg_virt(msg->sgt.sgl);
+	*data = cmd;
+}
+
+static inline u32 cs_get_cmd(struct hsi_msg *msg)
+{
+	u32 *data = sg_virt(msg->sgt.sgl);
+	return *data;
+}
+
+static void cs_release_cmd(struct hsi_msg *msg)
+{
+	struct cs_hsi_iface *hi = msg->context;
+
+	list_add_tail(&msg->link, &hi->cmdqueue);
+}
+
+static void cs_cmd_destructor(struct hsi_msg *msg)
+{
+	struct cs_hsi_iface *hi = msg->context;
+
+	spin_lock(&hi->lock);
+
+	dev_dbg(&cs_char_data.cl->device, "control cmd destructor\n");
+
+	if (hi->iface_state != CS_STATE_CLOSED)
+		dev_err(&hi->cl->device, "Cmd flushed while driver active\n");
+
+	if (msg->ttype == HSI_MSG_READ)
+		hi->control_state &=
+			~(SSI_CHANNEL_STATE_POLL | SSI_CHANNEL_STATE_READING);
+	else if (msg->ttype == HSI_MSG_WRITE &&
+			hi->control_state & SSI_CHANNEL_STATE_WRITING)
+		hi->control_state &= ~SSI_CHANNEL_STATE_WRITING;
+
+	cs_release_cmd(msg);
+
+	spin_unlock(&hi->lock);
+}
+
+static struct hsi_msg *cs_claim_cmd(struct cs_hsi_iface* ssi)
+{
+	struct hsi_msg *msg;
+
+	BUG_ON(list_empty(&ssi->cmdqueue));
+
+	msg = list_first_entry(&ssi->cmdqueue, struct hsi_msg, link);
+	list_del(&msg->link);
+	msg->destructor = cs_cmd_destructor;
+
+	return msg;
+}
+
+static void cs_free_cmds(struct cs_hsi_iface *ssi)
+{
+	struct hsi_msg *msg, *tmp;
+
+	list_for_each_entry_safe(msg, tmp, &ssi->cmdqueue, link) {
+		list_del(&msg->link);
+		msg->destructor = NULL;
+		kfree(sg_virt(msg->sgt.sgl));
+		hsi_free_msg(msg);
+	}
+}
+
+static int cs_alloc_cmds(struct cs_hsi_iface *hi)
+{
+	struct hsi_msg *msg;
+	u32 *buf;
+	unsigned int i;
+
+	INIT_LIST_HEAD(&hi->cmdqueue);
+
+	for (i = 0; i < CS_MAX_CMDS; i++) {
+		msg = hsi_alloc_msg(1, GFP_KERNEL);
+		if (!msg)
+			goto out;
+		buf = kmalloc(sizeof(*buf), GFP_KERNEL);
+		if (!buf) {
+			hsi_free_msg(msg);
+			goto out;
+		}
+		sg_init_one(msg->sgt.sgl, buf, sizeof(*buf));
+		msg->channel = cs_char_data.channel_id_cmd;
+		msg->context = hi;
+		list_add_tail(&msg->link, &hi->cmdqueue);
+	}
+
+	return 0;
+
+out:
+	cs_free_cmds(hi);
+	return -ENOMEM;
+}
+
+static void cs_hsi_data_destructor(struct hsi_msg *msg)
+{
+	struct cs_hsi_iface *hi = msg->context;
+	const char *dir = (msg->ttype == HSI_MSG_READ) ? "TX" : "RX";
+
+	dev_dbg(&cs_char_data.cl->device, "Freeing data %s message\n", dir);
+
+	spin_lock(&hi->lock);
+	if (hi->iface_state != CS_STATE_CLOSED)
+		dev_err(&cs_char_data.cl->device,
+				"Data %s flush while device active\n", dir);
+	if (msg->ttype == HSI_MSG_READ)
+		hi->data_state &=
+			~(SSI_CHANNEL_STATE_POLL | SSI_CHANNEL_STATE_READING);
+	else
+		hi->data_state &= ~SSI_CHANNEL_STATE_WRITING;
+
+	msg->status = HSI_STATUS_COMPLETED;
+	if (unlikely(waitqueue_active(&hi->datawait)))
+		wake_up_interruptible(&hi->datawait);
+
+	spin_unlock(&hi->lock);
+}
+
+static int cs_hsi_alloc_data(struct cs_hsi_iface *hi)
+{
+	struct hsi_msg *txmsg, *rxmsg;
+	int res = 0;
+
+	rxmsg = hsi_alloc_msg(1, GFP_KERNEL);
+	if (!rxmsg) {
+		res = -ENOMEM;
+		goto out1;
+	}
+	rxmsg->channel = cs_char_data.channel_id_data;
+	rxmsg->destructor = cs_hsi_data_destructor;
+	rxmsg->context = hi;
+
+	txmsg = hsi_alloc_msg(1, GFP_KERNEL);
+	if (!txmsg) {
+		res = -ENOMEM;
+		goto out2;
+	}
+	txmsg->channel = cs_char_data.channel_id_data;
+	txmsg->destructor = cs_hsi_data_destructor;
+	txmsg->context = hi;
+
+	hi->data_rx_msg = rxmsg;
+	hi->data_tx_msg = txmsg;
+
+	return 0;
+
+out2:
+	hsi_free_msg(rxmsg);
+out1:
+	return res;
+}
+
+static void cs_hsi_free_data_msg(struct hsi_msg *msg)
+{
+	WARN_ON(msg->status != HSI_STATUS_COMPLETED &&
+					msg->status != HSI_STATUS_ERROR);
+	hsi_free_msg(msg);
+}
+
+static void cs_hsi_free_data(struct cs_hsi_iface *hi)
+{
+	cs_hsi_free_data_msg(hi->data_rx_msg);
+	cs_hsi_free_data_msg(hi->data_tx_msg);
+}
+
+static inline void __cs_hsi_error_pre(struct cs_hsi_iface *hi,
+					struct hsi_msg *msg, const char *info,
+					unsigned int *state)
+{
+	spin_lock(&hi->lock);
+	dev_err(&hi->cl->device, "HSI %s error, msg %d, state %u\n",
+		info, msg->status, *state);
+}
+
+static inline void __cs_hsi_error_post(struct cs_hsi_iface *hi)
+{
+	spin_unlock(&hi->lock);
+}
+
+static inline void __cs_hsi_error_read_bits(unsigned int *state)
+{
+	*state |= SSI_CHANNEL_STATE_ERROR;
+	*state &= ~(SSI_CHANNEL_STATE_READING | SSI_CHANNEL_STATE_POLL);
+}
+
+static inline void __cs_hsi_error_write_bits(unsigned int *state)
+{
+	*state |= SSI_CHANNEL_STATE_ERROR;
+	*state &= ~SSI_CHANNEL_STATE_WRITING;
+}
+
+static void cs_hsi_control_read_error(struct cs_hsi_iface *hi,
+							struct hsi_msg *msg)
+{
+	__cs_hsi_error_pre(hi, msg, "control read", &hi->control_state);
+	cs_release_cmd(msg);
+	__cs_hsi_error_read_bits(&hi->control_state);
+	__cs_hsi_error_post(hi);
+}
+
+static void cs_hsi_control_write_error(struct cs_hsi_iface *hi,
+							struct hsi_msg *msg)
+{
+	__cs_hsi_error_pre(hi, msg, "control write", &hi->control_state);
+	cs_release_cmd(msg);
+	__cs_hsi_error_write_bits(&hi->control_state);
+	__cs_hsi_error_post(hi);
+
+}
+
+static void cs_hsi_data_read_error(struct cs_hsi_iface *hi, struct hsi_msg *msg)
+{
+	__cs_hsi_error_pre(hi, msg, "data read", &hi->data_state);
+	__cs_hsi_error_read_bits(&hi->data_state);
+	__cs_hsi_error_post(hi);
+}
+
+static void cs_hsi_data_write_error(struct cs_hsi_iface *hi,
+							struct hsi_msg *msg)
+{
+	__cs_hsi_error_pre(hi, msg, "data write", &hi->data_state);
+	__cs_hsi_error_write_bits(&hi->data_state);
+	__cs_hsi_error_post(hi);
+}
+
+static void cs_hsi_read_on_control_complete(struct hsi_msg *msg)
+{
+	u32 cmd = cs_get_cmd(msg);
+	struct cs_hsi_iface *hi = msg->context;
+
+	spin_lock(&hi->lock);
+	hi->control_state &= ~SSI_CHANNEL_STATE_READING;
+	if (msg->status == HSI_STATUS_ERROR) {
+		dev_err(&hi->cl->device, "Control RX error detected\n");
+		spin_unlock(&hi->lock);
+		cs_hsi_control_read_error(hi, msg);
+		goto out;
+	}
+	dev_dbg(&hi->cl->device, "Read on control: %08X\n", cmd);
+	cs_release_cmd(msg);
+	if (hi->flags & CS_FEAT_TSTAMP_RX_CTRL) {
+		struct timespec64 tspec;
+		struct cs_timestamp *tstamp =
+			&hi->mmap_cfg->tstamp_rx_ctrl;
+
+		ktime_get_ts64(&tspec);
+
+		tstamp->tv_sec = (__u32) tspec.tv_sec;
+		tstamp->tv_nsec = (__u32) tspec.tv_nsec;
+	}
+	spin_unlock(&hi->lock);
+
+	cs_notify_control(cmd);
+
+out:
+	cs_hsi_read_on_control(hi);
+}
+
+static void cs_hsi_peek_on_control_complete(struct hsi_msg *msg)
+{
+	struct cs_hsi_iface *hi = msg->context;
+	int ret;
+
+	if (msg->status == HSI_STATUS_ERROR) {
+		dev_err(&hi->cl->device, "Control peek RX error detected\n");
+		cs_hsi_control_read_error(hi, msg);
+		return;
+	}
+
+	WARN_ON(!(hi->control_state & SSI_CHANNEL_STATE_READING));
+
+	dev_dbg(&hi->cl->device, "Peek on control complete, reading\n");
+	msg->sgt.nents = 1;
+	msg->complete = cs_hsi_read_on_control_complete;
+	ret = hsi_async_read(hi->cl, msg);
+	if (ret)
+		cs_hsi_control_read_error(hi, msg);
+}
+
+static void cs_hsi_read_on_control(struct cs_hsi_iface *hi)
+{
+	struct hsi_msg *msg;
+	int ret;
+
+	spin_lock(&hi->lock);
+	if (hi->control_state & SSI_CHANNEL_STATE_READING) {
+		dev_err(&hi->cl->device, "Control read already pending (%d)\n",
+			hi->control_state);
+		spin_unlock(&hi->lock);
+		return;
+	}
+	if (hi->control_state & SSI_CHANNEL_STATE_ERROR) {
+		dev_err(&hi->cl->device, "Control read error (%d)\n",
+			hi->control_state);
+		spin_unlock(&hi->lock);
+		return;
+	}
+	hi->control_state |= SSI_CHANNEL_STATE_READING;
+	dev_dbg(&hi->cl->device, "Issuing RX on control\n");
+	msg = cs_claim_cmd(hi);
+	spin_unlock(&hi->lock);
+
+	msg->sgt.nents = 0;
+	msg->complete = cs_hsi_peek_on_control_complete;
+	ret = hsi_async_read(hi->cl, msg);
+	if (ret)
+		cs_hsi_control_read_error(hi, msg);
+}
+
+static void cs_hsi_write_on_control_complete(struct hsi_msg *msg)
+{
+	struct cs_hsi_iface *hi = msg->context;
+	if (msg->status == HSI_STATUS_COMPLETED) {
+		spin_lock(&hi->lock);
+		hi->control_state &= ~SSI_CHANNEL_STATE_WRITING;
+		cs_release_cmd(msg);
+		spin_unlock(&hi->lock);
+	} else if (msg->status == HSI_STATUS_ERROR) {
+		cs_hsi_control_write_error(hi, msg);
+	} else {
+		dev_err(&hi->cl->device,
+			"unexpected status in control write callback %d\n",
+			msg->status);
+	}
+}
+
+static int cs_hsi_write_on_control(struct cs_hsi_iface *hi, u32 message)
+{
+	struct hsi_msg *msg;
+	int ret;
+
+	spin_lock(&hi->lock);
+	if (hi->control_state & SSI_CHANNEL_STATE_ERROR) {
+		spin_unlock(&hi->lock);
+		return -EIO;
+	}
+	if (hi->control_state & SSI_CHANNEL_STATE_WRITING) {
+		dev_err(&hi->cl->device,
+			"Write still pending on control channel.\n");
+		spin_unlock(&hi->lock);
+		return -EBUSY;
+	}
+	hi->control_state |= SSI_CHANNEL_STATE_WRITING;
+	msg = cs_claim_cmd(hi);
+	spin_unlock(&hi->lock);
+
+	cs_set_cmd(msg, message);
+	msg->sgt.nents = 1;
+	msg->complete = cs_hsi_write_on_control_complete;
+	dev_dbg(&hi->cl->device,
+		"Sending control message %08X\n", message);
+	ret = hsi_async_write(hi->cl, msg);
+	if (ret) {
+		dev_err(&hi->cl->device,
+			"async_write failed with %d\n", ret);
+		cs_hsi_control_write_error(hi, msg);
+	}
+
+	/*
+	 * Make sure control read is always pending when issuing
+	 * new control writes. This is needed as the controller
+	 * may flush our messages if e.g. the peer device reboots
+	 * unexpectedly (and we cannot directly resubmit a new read from
+	 * the message destructor; see cs_cmd_destructor()).
+	 */
+	if (!(hi->control_state & SSI_CHANNEL_STATE_READING)) {
+		dev_err(&hi->cl->device, "Restarting control reads\n");
+		cs_hsi_read_on_control(hi);
+	}
+
+	return 0;
+}
+
+static void cs_hsi_read_on_data_complete(struct hsi_msg *msg)
+{
+	struct cs_hsi_iface *hi = msg->context;
+	u32 payload;
+
+	if (unlikely(msg->status == HSI_STATUS_ERROR)) {
+		cs_hsi_data_read_error(hi, msg);
+		return;
+	}
+
+	spin_lock(&hi->lock);
+	WARN_ON(!(hi->data_state & SSI_CHANNEL_STATE_READING));
+	hi->data_state &= ~SSI_CHANNEL_STATE_READING;
+	payload = CS_RX_DATA_RECEIVED;
+	payload |= hi->rx_slot;
+	hi->rx_slot++;
+	hi->rx_slot %= hi->rx_ptr_boundary;
+	/* expose current rx ptr in mmap area */
+	hi->mmap_cfg->rx_ptr = hi->rx_slot;
+	if (unlikely(waitqueue_active(&hi->datawait)))
+		wake_up_interruptible(&hi->datawait);
+	spin_unlock(&hi->lock);
+
+	cs_notify_data(payload, hi->rx_bufs);
+	cs_hsi_read_on_data(hi);
+}
+
+static void cs_hsi_peek_on_data_complete(struct hsi_msg *msg)
+{
+	struct cs_hsi_iface *hi = msg->context;
+	u32 *address;
+	int ret;
+
+	if (unlikely(msg->status == HSI_STATUS_ERROR)) {
+		cs_hsi_data_read_error(hi, msg);
+		return;
+	}
+	if (unlikely(hi->iface_state != CS_STATE_CONFIGURED)) {
+		dev_err(&hi->cl->device, "Data received in invalid state\n");
+		cs_hsi_data_read_error(hi, msg);
+		return;
+	}
+
+	spin_lock(&hi->lock);
+	WARN_ON(!(hi->data_state & SSI_CHANNEL_STATE_POLL));
+	hi->data_state &= ~SSI_CHANNEL_STATE_POLL;
+	hi->data_state |= SSI_CHANNEL_STATE_READING;
+	spin_unlock(&hi->lock);
+
+	address = (u32 *)(hi->mmap_base +
+				hi->rx_offsets[hi->rx_slot % hi->rx_bufs]);
+	sg_init_one(msg->sgt.sgl, address, hi->buf_size);
+	msg->sgt.nents = 1;
+	msg->complete = cs_hsi_read_on_data_complete;
+	ret = hsi_async_read(hi->cl, msg);
+	if (ret)
+		cs_hsi_data_read_error(hi, msg);
+}
+
+/*
+ * Read/write transaction is ongoing. Returns false if in
+ * SSI_CHANNEL_STATE_POLL state.
+ */
+static inline int cs_state_xfer_active(unsigned int state)
+{
+	return (state & SSI_CHANNEL_STATE_WRITING) ||
+		(state & SSI_CHANNEL_STATE_READING);
+}
+
+/*
+ * No pending read/writes
+ */
+static inline int cs_state_idle(unsigned int state)
+{
+	return !(state & ~SSI_CHANNEL_STATE_ERROR);
+}
+
+static void cs_hsi_read_on_data(struct cs_hsi_iface *hi)
+{
+	struct hsi_msg *rxmsg;
+	int ret;
+
+	spin_lock(&hi->lock);
+	if (hi->data_state &
+		(SSI_CHANNEL_STATE_READING | SSI_CHANNEL_STATE_POLL)) {
+		dev_dbg(&hi->cl->device, "Data read already pending (%u)\n",
+			hi->data_state);
+		spin_unlock(&hi->lock);
+		return;
+	}
+	hi->data_state |= SSI_CHANNEL_STATE_POLL;
+	spin_unlock(&hi->lock);
+
+	rxmsg = hi->data_rx_msg;
+	sg_init_one(rxmsg->sgt.sgl, (void *)hi->mmap_base, 0);
+	rxmsg->sgt.nents = 0;
+	rxmsg->complete = cs_hsi_peek_on_data_complete;
+
+	ret = hsi_async_read(hi->cl, rxmsg);
+	if (ret)
+		cs_hsi_data_read_error(hi, rxmsg);
+}
+
+static void cs_hsi_write_on_data_complete(struct hsi_msg *msg)
+{
+	struct cs_hsi_iface *hi = msg->context;
+
+	if (msg->status == HSI_STATUS_COMPLETED) {
+		spin_lock(&hi->lock);
+		hi->data_state &= ~SSI_CHANNEL_STATE_WRITING;
+		if (unlikely(waitqueue_active(&hi->datawait)))
+			wake_up_interruptible(&hi->datawait);
+		spin_unlock(&hi->lock);
+	} else {
+		cs_hsi_data_write_error(hi, msg);
+	}
+}
+
+static int cs_hsi_write_on_data(struct cs_hsi_iface *hi, unsigned int slot)
+{
+	u32 *address;
+	struct hsi_msg *txmsg;
+	int ret;
+
+	spin_lock(&hi->lock);
+	if (hi->iface_state != CS_STATE_CONFIGURED) {
+		dev_err(&hi->cl->device, "Not configured, aborting\n");
+		ret = -EINVAL;
+		goto error;
+	}
+	if (hi->data_state & SSI_CHANNEL_STATE_ERROR) {
+		dev_err(&hi->cl->device, "HSI error, aborting\n");
+		ret = -EIO;
+		goto error;
+	}
+	if (hi->data_state & SSI_CHANNEL_STATE_WRITING) {
+		dev_err(&hi->cl->device, "Write pending on data channel.\n");
+		ret = -EBUSY;
+		goto error;
+	}
+	hi->data_state |= SSI_CHANNEL_STATE_WRITING;
+	spin_unlock(&hi->lock);
+
+	hi->tx_slot = slot;
+	address = (u32 *)(hi->mmap_base + hi->tx_offsets[hi->tx_slot]);
+	txmsg = hi->data_tx_msg;
+	sg_init_one(txmsg->sgt.sgl, address, hi->buf_size);
+	txmsg->complete = cs_hsi_write_on_data_complete;
+	ret = hsi_async_write(hi->cl, txmsg);
+	if (ret)
+		cs_hsi_data_write_error(hi, txmsg);
+
+	return ret;
+
+error:
+	spin_unlock(&hi->lock);
+	if (ret == -EIO)
+		cs_hsi_data_write_error(hi, hi->data_tx_msg);
+
+	return ret;
+}
+
+static unsigned int cs_hsi_get_state(struct cs_hsi_iface *hi)
+{
+	return hi->iface_state;
+}
+
+static int cs_hsi_command(struct cs_hsi_iface *hi, u32 cmd)
+{
+	int ret = 0;
+
+	local_bh_disable();
+	switch (cmd & TARGET_MASK) {
+	case TARGET_REMOTE:
+		ret = cs_hsi_write_on_control(hi, cmd);
+		break;
+	case TARGET_LOCAL:
+		if ((cmd & CS_CMD_MASK) == CS_TX_DATA_READY)
+			ret = cs_hsi_write_on_data(hi, cmd & CS_PARAM_MASK);
+		else
+			ret = -EINVAL;
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+	local_bh_enable();
+
+	return ret;
+}
+
+static void cs_hsi_set_wakeline(struct cs_hsi_iface *hi, bool new_state)
+{
+	int change = 0;
+
+	spin_lock_bh(&hi->lock);
+	if (hi->wakeline_state != new_state) {
+		hi->wakeline_state = new_state;
+		change = 1;
+		dev_dbg(&hi->cl->device, "setting wake line to %d (%p)\n",
+			new_state, hi->cl);
+	}
+	spin_unlock_bh(&hi->lock);
+
+	if (change) {
+		if (new_state)
+			ssip_slave_start_tx(hi->master);
+		else
+			ssip_slave_stop_tx(hi->master);
+	}
+
+	dev_dbg(&hi->cl->device, "wake line set to %d (%p)\n",
+		new_state, hi->cl);
+}
+
+static void set_buffer_sizes(struct cs_hsi_iface *hi, int rx_bufs, int tx_bufs)
+{
+	hi->rx_bufs = rx_bufs;
+	hi->tx_bufs = tx_bufs;
+	hi->mmap_cfg->rx_bufs = rx_bufs;
+	hi->mmap_cfg->tx_bufs = tx_bufs;
+
+	if (hi->flags & CS_FEAT_ROLLING_RX_COUNTER) {
+		/*
+		 * For more robust overrun detection, let the rx
+		 * pointer run in range 0..'boundary-1'. Boundary
+		 * is a multiple of rx_bufs, and limited in max size
+		 * by RX_PTR_MAX_SHIFT to allow for fast ptr-diff
+		 * calculation.
+		 */
+		hi->rx_ptr_boundary = (rx_bufs << RX_PTR_BOUNDARY_SHIFT);
+		hi->mmap_cfg->rx_ptr_boundary = hi->rx_ptr_boundary;
+	} else {
+		hi->rx_ptr_boundary = hi->rx_bufs;
+	}
+}
+
+static int check_buf_params(struct cs_hsi_iface *hi,
+					const struct cs_buffer_config *buf_cfg)
+{
+	size_t buf_size_aligned = L1_CACHE_ALIGN(buf_cfg->buf_size) *
+					(buf_cfg->rx_bufs + buf_cfg->tx_bufs);
+	size_t ctrl_size_aligned = L1_CACHE_ALIGN(sizeof(*hi->mmap_cfg));
+	int r = 0;
+
+	if (buf_cfg->rx_bufs > CS_MAX_BUFFERS ||
+					buf_cfg->tx_bufs > CS_MAX_BUFFERS) {
+		r = -EINVAL;
+	} else if ((buf_size_aligned + ctrl_size_aligned) >= hi->mmap_size) {
+		dev_err(&hi->cl->device, "No space for the requested buffer "
+			"configuration\n");
+		r = -ENOBUFS;
+	}
+
+	return r;
+}
+
+/*
+ * Block until pending data transfers have completed.
+ */
+static int cs_hsi_data_sync(struct cs_hsi_iface *hi)
+{
+	int r = 0;
+
+	spin_lock_bh(&hi->lock);
+
+	if (!cs_state_xfer_active(hi->data_state)) {
+		dev_dbg(&hi->cl->device, "hsi_data_sync break, idle\n");
+		goto out;
+	}
+
+	for (;;) {
+		int s;
+		DEFINE_WAIT(wait);
+		if (!cs_state_xfer_active(hi->data_state))
+			goto out;
+		if (signal_pending(current)) {
+			r = -ERESTARTSYS;
+			goto out;
+		}
+		/*
+		 * prepare_to_wait must be called with hi->lock held
+		 * so that callbacks can check for waitqueue_active()
+		 */
+		prepare_to_wait(&hi->datawait, &wait, TASK_INTERRUPTIBLE);
+		spin_unlock_bh(&hi->lock);
+		s = schedule_timeout(
+			msecs_to_jiffies(CS_HSI_TRANSFER_TIMEOUT_MS));
+		spin_lock_bh(&hi->lock);
+		finish_wait(&hi->datawait, &wait);
+		if (!s) {
+			dev_dbg(&hi->cl->device,
+				"hsi_data_sync timeout after %d ms\n",
+				CS_HSI_TRANSFER_TIMEOUT_MS);
+			r = -EIO;
+			goto out;
+		}
+	}
+
+out:
+	spin_unlock_bh(&hi->lock);
+	dev_dbg(&hi->cl->device, "hsi_data_sync done with res %d\n", r);
+
+	return r;
+}
+
+static void cs_hsi_data_enable(struct cs_hsi_iface *hi,
+					struct cs_buffer_config *buf_cfg)
+{
+	unsigned int data_start, i;
+
+	BUG_ON(hi->buf_size == 0);
+
+	set_buffer_sizes(hi, buf_cfg->rx_bufs, buf_cfg->tx_bufs);
+
+	hi->slot_size = L1_CACHE_ALIGN(hi->buf_size);
+	dev_dbg(&hi->cl->device,
+			"setting slot size to %u, buf size %u, align %u\n",
+			hi->slot_size, hi->buf_size, L1_CACHE_BYTES);
+
+	data_start = L1_CACHE_ALIGN(sizeof(*hi->mmap_cfg));
+	dev_dbg(&hi->cl->device,
+			"setting data start at %u, cfg block %u, align %u\n",
+			data_start, sizeof(*hi->mmap_cfg), L1_CACHE_BYTES);
+
+	for (i = 0; i < hi->mmap_cfg->rx_bufs; i++) {
+		hi->rx_offsets[i] = data_start + i * hi->slot_size;
+		hi->mmap_cfg->rx_offsets[i] = hi->rx_offsets[i];
+		dev_dbg(&hi->cl->device, "DL buf #%u at %u\n",
+					i, hi->rx_offsets[i]);
+	}
+	for (i = 0; i < hi->mmap_cfg->tx_bufs; i++) {
+		hi->tx_offsets[i] = data_start +
+			(i + hi->mmap_cfg->rx_bufs) * hi->slot_size;
+		hi->mmap_cfg->tx_offsets[i] = hi->tx_offsets[i];
+		dev_dbg(&hi->cl->device, "UL buf #%u at %u\n",
+					i, hi->rx_offsets[i]);
+	}
+
+	hi->iface_state = CS_STATE_CONFIGURED;
+}
+
+static void cs_hsi_data_disable(struct cs_hsi_iface *hi, int old_state)
+{
+	if (old_state == CS_STATE_CONFIGURED) {
+		dev_dbg(&hi->cl->device,
+			"closing data channel with slot size 0\n");
+		hi->iface_state = CS_STATE_OPENED;
+	}
+}
+
+static int cs_hsi_buf_config(struct cs_hsi_iface *hi,
+					struct cs_buffer_config *buf_cfg)
+{
+	int r = 0;
+	unsigned int old_state = hi->iface_state;
+
+	spin_lock_bh(&hi->lock);
+	/* Prevent new transactions during buffer reconfig */
+	if (old_state == CS_STATE_CONFIGURED)
+		hi->iface_state = CS_STATE_OPENED;
+	spin_unlock_bh(&hi->lock);
+
+	/*
+	 * make sure that no non-zero data reads are ongoing before
+	 * proceeding to change the buffer layout
+	 */
+	r = cs_hsi_data_sync(hi);
+	if (r < 0)
+		return r;
+
+	WARN_ON(cs_state_xfer_active(hi->data_state));
+
+	spin_lock_bh(&hi->lock);
+	r = check_buf_params(hi, buf_cfg);
+	if (r < 0)
+		goto error;
+
+	hi->buf_size = buf_cfg->buf_size;
+	hi->mmap_cfg->buf_size = hi->buf_size;
+	hi->flags = buf_cfg->flags;
+
+	hi->rx_slot = 0;
+	hi->tx_slot = 0;
+	hi->slot_size = 0;
+
+	if (hi->buf_size)
+		cs_hsi_data_enable(hi, buf_cfg);
+	else
+		cs_hsi_data_disable(hi, old_state);
+
+	spin_unlock_bh(&hi->lock);
+
+	if (old_state != hi->iface_state) {
+		if (hi->iface_state == CS_STATE_CONFIGURED) {
+			cpu_latency_qos_add_request(&hi->pm_qos_req,
+				CS_QOS_LATENCY_FOR_DATA_USEC);
+			local_bh_disable();
+			cs_hsi_read_on_data(hi);
+			local_bh_enable();
+		} else if (old_state == CS_STATE_CONFIGURED) {
+			cpu_latency_qos_remove_request(&hi->pm_qos_req);
+		}
+	}
+	return r;
+
+error:
+	spin_unlock_bh(&hi->lock);
+	return r;
+}
+
+static int cs_hsi_start(struct cs_hsi_iface **hi, struct hsi_client *cl,
+			unsigned long mmap_base, unsigned long mmap_size)
+{
+	int err = 0;
+	struct cs_hsi_iface *hsi_if = kzalloc(sizeof(*hsi_if), GFP_KERNEL);
+
+	dev_dbg(&cl->device, "cs_hsi_start\n");
+
+	if (!hsi_if) {
+		err = -ENOMEM;
+		goto leave0;
+	}
+	spin_lock_init(&hsi_if->lock);
+	hsi_if->cl = cl;
+	hsi_if->iface_state = CS_STATE_CLOSED;
+	hsi_if->mmap_cfg = (struct cs_mmap_config_block *)mmap_base;
+	hsi_if->mmap_base = mmap_base;
+	hsi_if->mmap_size = mmap_size;
+	memset(hsi_if->mmap_cfg, 0, sizeof(*hsi_if->mmap_cfg));
+	init_waitqueue_head(&hsi_if->datawait);
+	err = cs_alloc_cmds(hsi_if);
+	if (err < 0) {
+		dev_err(&cl->device, "Unable to alloc HSI messages\n");
+		goto leave1;
+	}
+	err = cs_hsi_alloc_data(hsi_if);
+	if (err < 0) {
+		dev_err(&cl->device, "Unable to alloc HSI messages for data\n");
+		goto leave2;
+	}
+	err = hsi_claim_port(cl, 1);
+	if (err < 0) {
+		dev_err(&cl->device,
+				"Could not open, HSI port already claimed\n");
+		goto leave3;
+	}
+	hsi_if->master = ssip_slave_get_master(cl);
+	if (IS_ERR(hsi_if->master)) {
+		err = PTR_ERR(hsi_if->master);
+		dev_err(&cl->device, "Could not get HSI master client\n");
+		goto leave4;
+	}
+	if (!ssip_slave_running(hsi_if->master)) {
+		err = -ENODEV;
+		dev_err(&cl->device,
+				"HSI port not initialized\n");
+		goto leave4;
+	}
+
+	hsi_if->iface_state = CS_STATE_OPENED;
+	local_bh_disable();
+	cs_hsi_read_on_control(hsi_if);
+	local_bh_enable();
+
+	dev_dbg(&cl->device, "cs_hsi_start...done\n");
+
+	BUG_ON(!hi);
+	*hi = hsi_if;
+
+	return 0;
+
+leave4:
+	hsi_release_port(cl);
+leave3:
+	cs_hsi_free_data(hsi_if);
+leave2:
+	cs_free_cmds(hsi_if);
+leave1:
+	kfree(hsi_if);
+leave0:
+	dev_dbg(&cl->device, "cs_hsi_start...done/error\n\n");
+
+	return err;
+}
+
+static void cs_hsi_stop(struct cs_hsi_iface *hi)
+{
+	dev_dbg(&hi->cl->device, "cs_hsi_stop\n");
+	cs_hsi_set_wakeline(hi, 0);
+	ssip_slave_put_master(hi->master);
+
+	/* hsi_release_port() needs to be called with CS_STATE_CLOSED */
+	hi->iface_state = CS_STATE_CLOSED;
+	hsi_release_port(hi->cl);
+
+	/*
+	 * hsi_release_port() should flush out all the pending
+	 * messages, so cs_state_idle() should be true for both
+	 * control and data channels.
+	 */
+	WARN_ON(!cs_state_idle(hi->control_state));
+	WARN_ON(!cs_state_idle(hi->data_state));
+
+	if (cpu_latency_qos_request_active(&hi->pm_qos_req))
+		cpu_latency_qos_remove_request(&hi->pm_qos_req);
+
+	spin_lock_bh(&hi->lock);
+	cs_hsi_free_data(hi);
+	cs_free_cmds(hi);
+	spin_unlock_bh(&hi->lock);
+	kfree(hi);
+}
+
+static vm_fault_t cs_char_vma_fault(struct vm_fault *vmf)
+{
+	struct cs_char *csdata = vmf->vma->vm_private_data;
+	struct page *page;
+
+	page = virt_to_page((void *)csdata->mmap_base);
+	get_page(page);
+	vmf->page = page;
+
+	return 0;
+}
+
+static const struct vm_operations_struct cs_char_vm_ops = {
+	.fault	= cs_char_vma_fault,
+};
+
+static int cs_char_fasync(int fd, struct file *file, int on)
+{
+	struct cs_char *csdata = file->private_data;
+
+	if (fasync_helper(fd, file, on, &csdata->async_queue) < 0)
+		return -EIO;
+
+	return 0;
+}
+
+static __poll_t cs_char_poll(struct file *file, poll_table *wait)
+{
+	struct cs_char *csdata = file->private_data;
+	__poll_t ret = 0;
+
+	poll_wait(file, &cs_char_data.wait, wait);
+	spin_lock_bh(&csdata->lock);
+	if (!list_empty(&csdata->chardev_queue))
+		ret = EPOLLIN | EPOLLRDNORM;
+	else if (!list_empty(&csdata->dataind_queue))
+		ret = EPOLLIN | EPOLLRDNORM;
+	spin_unlock_bh(&csdata->lock);
+
+	return ret;
+}
+
+static ssize_t cs_char_read(struct file *file, char __user *buf, size_t count,
+								loff_t *unused)
+{
+	struct cs_char *csdata = file->private_data;
+	u32 data;
+	ssize_t retval;
+
+	if (count < sizeof(data))
+		return -EINVAL;
+
+	for (;;) {
+		DEFINE_WAIT(wait);
+
+		spin_lock_bh(&csdata->lock);
+		if (!list_empty(&csdata->chardev_queue)) {
+			data = cs_pop_entry(&csdata->chardev_queue);
+		} else if (!list_empty(&csdata->dataind_queue)) {
+			data = cs_pop_entry(&csdata->dataind_queue);
+			csdata->dataind_pending--;
+		} else {
+			data = 0;
+		}
+		spin_unlock_bh(&csdata->lock);
+
+		if (data)
+			break;
+		if (file->f_flags & O_NONBLOCK) {
+			retval = -EAGAIN;
+			goto out;
+		} else if (signal_pending(current)) {
+			retval = -ERESTARTSYS;
+			goto out;
+		}
+		prepare_to_wait_exclusive(&csdata->wait, &wait,
+						TASK_INTERRUPTIBLE);
+		schedule();
+		finish_wait(&csdata->wait, &wait);
+	}
+
+	retval = put_user(data, (u32 __user *)buf);
+	if (!retval)
+		retval = sizeof(data);
+
+out:
+	return retval;
+}
+
+static ssize_t cs_char_write(struct file *file, const char __user *buf,
+						size_t count, loff_t *unused)
+{
+	struct cs_char *csdata = file->private_data;
+	u32 data;
+	int err;
+	ssize_t	retval;
+
+	if (count < sizeof(data))
+		return -EINVAL;
+
+	if (get_user(data, (u32 __user *)buf))
+		retval = -EFAULT;
+	else
+		retval = count;
+
+	err = cs_hsi_command(csdata->hi, data);
+	if (err < 0)
+		retval = err;
+
+	return retval;
+}
+
+static long cs_char_ioctl(struct file *file, unsigned int cmd,
+				unsigned long arg)
+{
+	struct cs_char *csdata = file->private_data;
+	int r = 0;
+
+	switch (cmd) {
+	case CS_GET_STATE: {
+		unsigned int state;
+
+		state = cs_hsi_get_state(csdata->hi);
+		if (copy_to_user((void __user *)arg, &state, sizeof(state)))
+			r = -EFAULT;
+
+		break;
+	}
+	case CS_SET_WAKELINE: {
+		unsigned int state;
+
+		if (copy_from_user(&state, (void __user *)arg, sizeof(state))) {
+			r = -EFAULT;
+			break;
+		}
+
+		if (state > 1) {
+			r = -EINVAL;
+			break;
+		}
+
+		cs_hsi_set_wakeline(csdata->hi, !!state);
+
+		break;
+	}
+	case CS_GET_IF_VERSION: {
+		unsigned int ifver = CS_IF_VERSION;
+
+		if (copy_to_user((void __user *)arg, &ifver, sizeof(ifver)))
+			r = -EFAULT;
+
+		break;
+	}
+	case CS_CONFIG_BUFS: {
+		struct cs_buffer_config buf_cfg;
+
+		if (copy_from_user(&buf_cfg, (void __user *)arg,
+							sizeof(buf_cfg)))
+			r = -EFAULT;
+		else
+			r = cs_hsi_buf_config(csdata->hi, &buf_cfg);
+
+		break;
+	}
+	default:
+		r = -ENOTTY;
+		break;
+	}
+
+	return r;
+}
+
+static int cs_char_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	if (vma->vm_end < vma->vm_start)
+		return -EINVAL;
+
+	if (vma_pages(vma) != 1)
+		return -EINVAL;
+
+	vma->vm_flags |= VM_IO | VM_DONTDUMP | VM_DONTEXPAND;
+	vma->vm_ops = &cs_char_vm_ops;
+	vma->vm_private_data = file->private_data;
+
+	return 0;
+}
+
+static int cs_char_open(struct inode *unused, struct file *file)
+{
+	int ret = 0;
+	unsigned long p;
+
+	spin_lock_bh(&cs_char_data.lock);
+	if (cs_char_data.opened) {
+		ret = -EBUSY;
+		spin_unlock_bh(&cs_char_data.lock);
+		goto out1;
+	}
+	cs_char_data.opened = 1;
+	cs_char_data.dataind_pending = 0;
+	spin_unlock_bh(&cs_char_data.lock);
+
+	p = get_zeroed_page(GFP_KERNEL);
+	if (!p) {
+		ret = -ENOMEM;
+		goto out2;
+	}
+
+	ret = cs_hsi_start(&cs_char_data.hi, cs_char_data.cl, p, CS_MMAP_SIZE);
+	if (ret) {
+		dev_err(&cs_char_data.cl->device, "Unable to initialize HSI\n");
+		goto out3;
+	}
+
+	/* these are only used in release so lock not needed */
+	cs_char_data.mmap_base = p;
+	cs_char_data.mmap_size = CS_MMAP_SIZE;
+
+	file->private_data = &cs_char_data;
+
+	return 0;
+
+out3:
+	free_page(p);
+out2:
+	spin_lock_bh(&cs_char_data.lock);
+	cs_char_data.opened = 0;
+	spin_unlock_bh(&cs_char_data.lock);
+out1:
+	return ret;
+}
+
+static void cs_free_char_queue(struct list_head *head)
+{
+	struct char_queue *entry;
+	struct list_head *cursor, *next;
+
+	if (!list_empty(head)) {
+		list_for_each_safe(cursor, next, head) {
+			entry = list_entry(cursor, struct char_queue, list);
+			list_del(&entry->list);
+			kfree(entry);
+		}
+	}
+
+}
+
+static int cs_char_release(struct inode *unused, struct file *file)
+{
+	struct cs_char *csdata = file->private_data;
+
+	cs_hsi_stop(csdata->hi);
+	spin_lock_bh(&csdata->lock);
+	csdata->hi = NULL;
+	free_page(csdata->mmap_base);
+	cs_free_char_queue(&csdata->chardev_queue);
+	cs_free_char_queue(&csdata->dataind_queue);
+	csdata->opened = 0;
+	spin_unlock_bh(&csdata->lock);
+
+	return 0;
+}
+
+static const struct file_operations cs_char_fops = {
+	.owner		= THIS_MODULE,
+	.read		= cs_char_read,
+	.write		= cs_char_write,
+	.poll		= cs_char_poll,
+	.unlocked_ioctl	= cs_char_ioctl,
+	.mmap		= cs_char_mmap,
+	.open		= cs_char_open,
+	.release	= cs_char_release,
+	.fasync		= cs_char_fasync,
+};
+
+static struct miscdevice cs_char_miscdev = {
+	.minor	= MISC_DYNAMIC_MINOR,
+	.name	= "cmt_speech",
+	.fops	= &cs_char_fops
+};
+
+static int cs_hsi_client_probe(struct device *dev)
+{
+	int err = 0;
+	struct hsi_client *cl = to_hsi_client(dev);
+
+	dev_dbg(dev, "hsi_client_probe\n");
+	init_waitqueue_head(&cs_char_data.wait);
+	spin_lock_init(&cs_char_data.lock);
+	cs_char_data.opened = 0;
+	cs_char_data.cl = cl;
+	cs_char_data.hi = NULL;
+	INIT_LIST_HEAD(&cs_char_data.chardev_queue);
+	INIT_LIST_HEAD(&cs_char_data.dataind_queue);
+
+	cs_char_data.channel_id_cmd = hsi_get_channel_id_by_name(cl,
+		"speech-control");
+	if (cs_char_data.channel_id_cmd < 0) {
+		err = cs_char_data.channel_id_cmd;
+		dev_err(dev, "Could not get cmd channel (%d)\n", err);
+		return err;
+	}
+
+	cs_char_data.channel_id_data = hsi_get_channel_id_by_name(cl,
+		"speech-data");
+	if (cs_char_data.channel_id_data < 0) {
+		err = cs_char_data.channel_id_data;
+		dev_err(dev, "Could not get data channel (%d)\n", err);
+		return err;
+	}
+
+	err = misc_register(&cs_char_miscdev);
+	if (err)
+		dev_err(dev, "Failed to register: %d\n", err);
+
+	return err;
+}
+
+static int cs_hsi_client_remove(struct device *dev)
+{
+	struct cs_hsi_iface *hi;
+
+	dev_dbg(dev, "hsi_client_remove\n");
+	misc_deregister(&cs_char_miscdev);
+	spin_lock_bh(&cs_char_data.lock);
+	hi = cs_char_data.hi;
+	cs_char_data.hi = NULL;
+	spin_unlock_bh(&cs_char_data.lock);
+	if (hi)
+		cs_hsi_stop(hi);
+
+	return 0;
+}
+
+static struct hsi_client_driver cs_hsi_driver = {
+	.driver = {
+		.name	= "cmt-speech",
+		.owner	= THIS_MODULE,
+		.probe	= cs_hsi_client_probe,
+		.remove	= cs_hsi_client_remove,
+	},
+};
+
+static int __init cs_char_init(void)
+{
+	pr_info("CMT speech driver added\n");
+	return hsi_register_client_driver(&cs_hsi_driver);
+}
+module_init(cs_char_init);
+
+static void __exit cs_char_exit(void)
+{
+	hsi_unregister_client_driver(&cs_hsi_driver);
+	pr_info("CMT speech driver removed\n");
+}
+module_exit(cs_char_exit);
+
+MODULE_ALIAS("hsi:cmt-speech");
+MODULE_AUTHOR("Kai Vehmanen <kai.vehmanen@nokia.com>");
+MODULE_AUTHOR("Peter Ujfalusi <peter.ujfalusi@nokia.com>");
+MODULE_DESCRIPTION("CMT speech driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/hsi/clients/hsi_char.c b/drivers/hsi/clients/hsi_char.c
new file mode 100644
index 000000000..71ce7dbfe
--- /dev/null
+++ b/drivers/hsi/clients/hsi_char.c
@@ -0,0 +1,788 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * HSI character device driver, implements the character device
+ * interface.
+ *
+ * Copyright (C) 2010 Nokia Corporation. All rights reserved.
+ *
+ * Contact: Andras Domokos <andras.domokos@nokia.com>
+ */
+
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/atomic.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/kmemleak.h>
+#include <linux/ioctl.h>
+#include <linux/wait.h>
+#include <linux/fs.h>
+#include <linux/sched.h>
+#include <linux/device.h>
+#include <linux/cdev.h>
+#include <linux/uaccess.h>
+#include <linux/scatterlist.h>
+#include <linux/stat.h>
+#include <linux/hsi/hsi.h>
+#include <linux/hsi/hsi_char.h>
+
+#define HSC_DEVS		16 /* Num of channels */
+#define HSC_MSGS		4
+
+#define HSC_RXBREAK		0
+
+#define HSC_ID_BITS		6
+#define HSC_PORT_ID_BITS	4
+#define HSC_ID_MASK		3
+#define HSC_PORT_ID_MASK	3
+#define HSC_CH_MASK		0xf
+
+/*
+ * We support up to 4 controllers that can have up to 4
+ * ports, which should currently be more than enough.
+ */
+#define HSC_BASEMINOR(id, port_id) \
+		((((id) & HSC_ID_MASK) << HSC_ID_BITS) | \
+		(((port_id) & HSC_PORT_ID_MASK) << HSC_PORT_ID_BITS))
+
+enum {
+	HSC_CH_OPEN,
+	HSC_CH_READ,
+	HSC_CH_WRITE,
+	HSC_CH_WLINE,
+};
+
+enum {
+	HSC_RX,
+	HSC_TX,
+};
+
+struct hsc_client_data;
+/**
+ * struct hsc_channel - hsi_char internal channel data
+ * @ch: channel number
+ * @flags: Keeps state of the channel (open/close, reading, writing)
+ * @free_msgs_list: List of free HSI messages/requests
+ * @rx_msgs_queue: List of pending RX requests
+ * @tx_msgs_queue: List of pending TX requests
+ * @lock: Serialize access to the lists
+ * @cl: reference to the associated hsi_client
+ * @cl_data: reference to the client data that this channels belongs to
+ * @rx_wait: RX requests wait queue
+ * @tx_wait: TX requests wait queue
+ */
+struct hsc_channel {
+	unsigned int		ch;
+	unsigned long		flags;
+	struct list_head	free_msgs_list;
+	struct list_head	rx_msgs_queue;
+	struct list_head	tx_msgs_queue;
+	spinlock_t		lock;
+	struct hsi_client	*cl;
+	struct hsc_client_data *cl_data;
+	wait_queue_head_t	rx_wait;
+	wait_queue_head_t	tx_wait;
+};
+
+/**
+ * struct hsc_client_data - hsi_char internal client data
+ * @cdev: Characther device associated to the hsi_client
+ * @lock: Lock to serialize open/close access
+ * @flags: Keeps track of port state (rx hwbreak armed)
+ * @usecnt: Use count for claiming the HSI port (mutex protected)
+ * @cl: Referece to the HSI client
+ * @channels: Array of channels accessible by the client
+ */
+struct hsc_client_data {
+	struct cdev		cdev;
+	struct mutex		lock;
+	unsigned long		flags;
+	unsigned int		usecnt;
+	struct hsi_client	*cl;
+	struct hsc_channel	channels[HSC_DEVS];
+};
+
+/* Stores the major number dynamically allocated for hsi_char */
+static unsigned int hsc_major;
+/* Maximum buffer size that hsi_char will accept from userspace */
+static unsigned int max_data_size = 0x1000;
+module_param(max_data_size, uint, 0);
+MODULE_PARM_DESC(max_data_size, "max read/write data size [4,8..65536] (^2)");
+
+static void hsc_add_tail(struct hsc_channel *channel, struct hsi_msg *msg,
+							struct list_head *queue)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&channel->lock, flags);
+	list_add_tail(&msg->link, queue);
+	spin_unlock_irqrestore(&channel->lock, flags);
+}
+
+static struct hsi_msg *hsc_get_first_msg(struct hsc_channel *channel,
+							struct list_head *queue)
+{
+	struct hsi_msg *msg = NULL;
+	unsigned long flags;
+
+	spin_lock_irqsave(&channel->lock, flags);
+
+	if (list_empty(queue))
+		goto out;
+
+	msg = list_first_entry(queue, struct hsi_msg, link);
+	list_del(&msg->link);
+out:
+	spin_unlock_irqrestore(&channel->lock, flags);
+
+	return msg;
+}
+
+static inline void hsc_msg_free(struct hsi_msg *msg)
+{
+	kfree(sg_virt(msg->sgt.sgl));
+	hsi_free_msg(msg);
+}
+
+static void hsc_free_list(struct list_head *list)
+{
+	struct hsi_msg *msg, *tmp;
+
+	list_for_each_entry_safe(msg, tmp, list, link) {
+		list_del(&msg->link);
+		hsc_msg_free(msg);
+	}
+}
+
+static void hsc_reset_list(struct hsc_channel *channel, struct list_head *l)
+{
+	unsigned long flags;
+	LIST_HEAD(list);
+
+	spin_lock_irqsave(&channel->lock, flags);
+	list_splice_init(l, &list);
+	spin_unlock_irqrestore(&channel->lock, flags);
+
+	hsc_free_list(&list);
+}
+
+static inline struct hsi_msg *hsc_msg_alloc(unsigned int alloc_size)
+{
+	struct hsi_msg *msg;
+	void *buf;
+
+	msg = hsi_alloc_msg(1, GFP_KERNEL);
+	if (!msg)
+		goto out;
+	buf = kmalloc(alloc_size, GFP_KERNEL);
+	if (!buf) {
+		hsi_free_msg(msg);
+		goto out;
+	}
+	sg_init_one(msg->sgt.sgl, buf, alloc_size);
+	/* Ignore false positive, due to sg pointer handling */
+	kmemleak_ignore(buf);
+
+	return msg;
+out:
+	return NULL;
+}
+
+static inline int hsc_msgs_alloc(struct hsc_channel *channel)
+{
+	struct hsi_msg *msg;
+	int i;
+
+	for (i = 0; i < HSC_MSGS; i++) {
+		msg = hsc_msg_alloc(max_data_size);
+		if (!msg)
+			goto out;
+		msg->channel = channel->ch;
+		list_add_tail(&msg->link, &channel->free_msgs_list);
+	}
+
+	return 0;
+out:
+	hsc_free_list(&channel->free_msgs_list);
+
+	return -ENOMEM;
+}
+
+static inline unsigned int hsc_msg_len_get(struct hsi_msg *msg)
+{
+	return msg->sgt.sgl->length;
+}
+
+static inline void hsc_msg_len_set(struct hsi_msg *msg, unsigned int len)
+{
+	msg->sgt.sgl->length = len;
+}
+
+static void hsc_rx_completed(struct hsi_msg *msg)
+{
+	struct hsc_client_data *cl_data = hsi_client_drvdata(msg->cl);
+	struct hsc_channel *channel = cl_data->channels + msg->channel;
+
+	if (test_bit(HSC_CH_READ, &channel->flags)) {
+		hsc_add_tail(channel, msg, &channel->rx_msgs_queue);
+		wake_up(&channel->rx_wait);
+	} else {
+		hsc_add_tail(channel, msg, &channel->free_msgs_list);
+	}
+}
+
+static void hsc_rx_msg_destructor(struct hsi_msg *msg)
+{
+	msg->status = HSI_STATUS_ERROR;
+	hsc_msg_len_set(msg, 0);
+	hsc_rx_completed(msg);
+}
+
+static void hsc_tx_completed(struct hsi_msg *msg)
+{
+	struct hsc_client_data *cl_data = hsi_client_drvdata(msg->cl);
+	struct hsc_channel *channel = cl_data->channels + msg->channel;
+
+	if (test_bit(HSC_CH_WRITE, &channel->flags)) {
+		hsc_add_tail(channel, msg, &channel->tx_msgs_queue);
+		wake_up(&channel->tx_wait);
+	} else {
+		hsc_add_tail(channel, msg, &channel->free_msgs_list);
+	}
+}
+
+static void hsc_tx_msg_destructor(struct hsi_msg *msg)
+{
+	msg->status = HSI_STATUS_ERROR;
+	hsc_msg_len_set(msg, 0);
+	hsc_tx_completed(msg);
+}
+
+static void hsc_break_req_destructor(struct hsi_msg *msg)
+{
+	struct hsc_client_data *cl_data = hsi_client_drvdata(msg->cl);
+
+	hsi_free_msg(msg);
+	clear_bit(HSC_RXBREAK, &cl_data->flags);
+}
+
+static void hsc_break_received(struct hsi_msg *msg)
+{
+	struct hsc_client_data *cl_data = hsi_client_drvdata(msg->cl);
+	struct hsc_channel *channel = cl_data->channels;
+	int i, ret;
+
+	/* Broadcast HWBREAK on all channels */
+	for (i = 0; i < HSC_DEVS; i++, channel++) {
+		struct hsi_msg *msg2;
+
+		if (!test_bit(HSC_CH_READ, &channel->flags))
+			continue;
+		msg2 = hsc_get_first_msg(channel, &channel->free_msgs_list);
+		if (!msg2)
+			continue;
+		clear_bit(HSC_CH_READ, &channel->flags);
+		hsc_msg_len_set(msg2, 0);
+		msg2->status = HSI_STATUS_COMPLETED;
+		hsc_add_tail(channel, msg2, &channel->rx_msgs_queue);
+		wake_up(&channel->rx_wait);
+	}
+	hsi_flush(msg->cl);
+	ret = hsi_async_read(msg->cl, msg);
+	if (ret < 0)
+		hsc_break_req_destructor(msg);
+}
+
+static int hsc_break_request(struct hsi_client *cl)
+{
+	struct hsc_client_data *cl_data = hsi_client_drvdata(cl);
+	struct hsi_msg *msg;
+	int ret;
+
+	if (test_and_set_bit(HSC_RXBREAK, &cl_data->flags))
+		return -EBUSY;
+
+	msg = hsi_alloc_msg(0, GFP_KERNEL);
+	if (!msg) {
+		clear_bit(HSC_RXBREAK, &cl_data->flags);
+		return -ENOMEM;
+	}
+	msg->break_frame = 1;
+	msg->complete = hsc_break_received;
+	msg->destructor = hsc_break_req_destructor;
+	ret = hsi_async_read(cl, msg);
+	if (ret < 0)
+		hsc_break_req_destructor(msg);
+
+	return ret;
+}
+
+static int hsc_break_send(struct hsi_client *cl)
+{
+	struct hsi_msg *msg;
+	int ret;
+
+	msg = hsi_alloc_msg(0, GFP_ATOMIC);
+	if (!msg)
+		return -ENOMEM;
+	msg->break_frame = 1;
+	msg->complete = hsi_free_msg;
+	msg->destructor = hsi_free_msg;
+	ret = hsi_async_write(cl, msg);
+	if (ret < 0)
+		hsi_free_msg(msg);
+
+	return ret;
+}
+
+static int hsc_rx_set(struct hsi_client *cl, struct hsc_rx_config *rxc)
+{
+	struct hsi_config tmp;
+	int ret;
+
+	if ((rxc->mode != HSI_MODE_STREAM) && (rxc->mode != HSI_MODE_FRAME))
+		return -EINVAL;
+	if ((rxc->channels == 0) || (rxc->channels > HSC_DEVS))
+		return -EINVAL;
+	if (rxc->channels & (rxc->channels - 1))
+		return -EINVAL;
+	if ((rxc->flow != HSI_FLOW_SYNC) && (rxc->flow != HSI_FLOW_PIPE))
+		return -EINVAL;
+	tmp = cl->rx_cfg;
+	cl->rx_cfg.mode = rxc->mode;
+	cl->rx_cfg.num_hw_channels = rxc->channels;
+	cl->rx_cfg.flow = rxc->flow;
+	ret = hsi_setup(cl);
+	if (ret < 0) {
+		cl->rx_cfg = tmp;
+		return ret;
+	}
+	if (rxc->mode == HSI_MODE_FRAME)
+		hsc_break_request(cl);
+
+	return ret;
+}
+
+static inline void hsc_rx_get(struct hsi_client *cl, struct hsc_rx_config *rxc)
+{
+	rxc->mode = cl->rx_cfg.mode;
+	rxc->channels = cl->rx_cfg.num_hw_channels;
+	rxc->flow = cl->rx_cfg.flow;
+}
+
+static int hsc_tx_set(struct hsi_client *cl, struct hsc_tx_config *txc)
+{
+	struct hsi_config tmp;
+	int ret;
+
+	if ((txc->mode != HSI_MODE_STREAM) && (txc->mode != HSI_MODE_FRAME))
+		return -EINVAL;
+	if ((txc->channels == 0) || (txc->channels > HSC_DEVS))
+		return -EINVAL;
+	if (txc->channels & (txc->channels - 1))
+		return -EINVAL;
+	if ((txc->arb_mode != HSI_ARB_RR) && (txc->arb_mode != HSI_ARB_PRIO))
+		return -EINVAL;
+	tmp = cl->tx_cfg;
+	cl->tx_cfg.mode = txc->mode;
+	cl->tx_cfg.num_hw_channels = txc->channels;
+	cl->tx_cfg.speed = txc->speed;
+	cl->tx_cfg.arb_mode = txc->arb_mode;
+	ret = hsi_setup(cl);
+	if (ret < 0) {
+		cl->tx_cfg = tmp;
+		return ret;
+	}
+
+	return ret;
+}
+
+static inline void hsc_tx_get(struct hsi_client *cl, struct hsc_tx_config *txc)
+{
+	txc->mode = cl->tx_cfg.mode;
+	txc->channels = cl->tx_cfg.num_hw_channels;
+	txc->speed = cl->tx_cfg.speed;
+	txc->arb_mode = cl->tx_cfg.arb_mode;
+}
+
+static ssize_t hsc_read(struct file *file, char __user *buf, size_t len,
+						loff_t *ppos __maybe_unused)
+{
+	struct hsc_channel *channel = file->private_data;
+	struct hsi_msg *msg;
+	ssize_t ret;
+
+	if (len == 0)
+		return 0;
+	if (!IS_ALIGNED(len, sizeof(u32)))
+		return -EINVAL;
+	if (len > max_data_size)
+		len = max_data_size;
+	if (channel->ch >= channel->cl->rx_cfg.num_hw_channels)
+		return -ECHRNG;
+	if (test_and_set_bit(HSC_CH_READ, &channel->flags))
+		return -EBUSY;
+	msg = hsc_get_first_msg(channel, &channel->free_msgs_list);
+	if (!msg) {
+		ret = -ENOSPC;
+		goto out;
+	}
+	hsc_msg_len_set(msg, len);
+	msg->complete = hsc_rx_completed;
+	msg->destructor = hsc_rx_msg_destructor;
+	ret = hsi_async_read(channel->cl, msg);
+	if (ret < 0) {
+		hsc_add_tail(channel, msg, &channel->free_msgs_list);
+		goto out;
+	}
+
+	ret = wait_event_interruptible(channel->rx_wait,
+					!list_empty(&channel->rx_msgs_queue));
+	if (ret < 0) {
+		clear_bit(HSC_CH_READ, &channel->flags);
+		hsi_flush(channel->cl);
+		return -EINTR;
+	}
+
+	msg = hsc_get_first_msg(channel, &channel->rx_msgs_queue);
+	if (msg) {
+		if (msg->status != HSI_STATUS_ERROR) {
+			ret = copy_to_user((void __user *)buf,
+			sg_virt(msg->sgt.sgl), hsc_msg_len_get(msg));
+			if (ret)
+				ret = -EFAULT;
+			else
+				ret = hsc_msg_len_get(msg);
+		} else {
+			ret = -EIO;
+		}
+		hsc_add_tail(channel, msg, &channel->free_msgs_list);
+	}
+out:
+	clear_bit(HSC_CH_READ, &channel->flags);
+
+	return ret;
+}
+
+static ssize_t hsc_write(struct file *file, const char __user *buf, size_t len,
+						loff_t *ppos __maybe_unused)
+{
+	struct hsc_channel *channel = file->private_data;
+	struct hsi_msg *msg;
+	ssize_t ret;
+
+	if ((len == 0) || !IS_ALIGNED(len, sizeof(u32)))
+		return -EINVAL;
+	if (len > max_data_size)
+		len = max_data_size;
+	if (channel->ch >= channel->cl->tx_cfg.num_hw_channels)
+		return -ECHRNG;
+	if (test_and_set_bit(HSC_CH_WRITE, &channel->flags))
+		return -EBUSY;
+	msg = hsc_get_first_msg(channel, &channel->free_msgs_list);
+	if (!msg) {
+		clear_bit(HSC_CH_WRITE, &channel->flags);
+		return -ENOSPC;
+	}
+	if (copy_from_user(sg_virt(msg->sgt.sgl), (void __user *)buf, len)) {
+		ret = -EFAULT;
+		goto out;
+	}
+	hsc_msg_len_set(msg, len);
+	msg->complete = hsc_tx_completed;
+	msg->destructor = hsc_tx_msg_destructor;
+	ret = hsi_async_write(channel->cl, msg);
+	if (ret < 0)
+		goto out;
+
+	ret = wait_event_interruptible(channel->tx_wait,
+					!list_empty(&channel->tx_msgs_queue));
+	if (ret < 0) {
+		clear_bit(HSC_CH_WRITE, &channel->flags);
+		hsi_flush(channel->cl);
+		return -EINTR;
+	}
+
+	msg = hsc_get_first_msg(channel, &channel->tx_msgs_queue);
+	if (msg) {
+		if (msg->status == HSI_STATUS_ERROR)
+			ret = -EIO;
+		else
+			ret = hsc_msg_len_get(msg);
+
+		hsc_add_tail(channel, msg, &channel->free_msgs_list);
+	}
+out:
+	clear_bit(HSC_CH_WRITE, &channel->flags);
+
+	return ret;
+}
+
+static long hsc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct hsc_channel *channel = file->private_data;
+	unsigned int state;
+	struct hsc_rx_config rxc;
+	struct hsc_tx_config txc;
+	long ret = 0;
+
+	switch (cmd) {
+	case HSC_RESET:
+		hsi_flush(channel->cl);
+		break;
+	case HSC_SET_PM:
+		if (copy_from_user(&state, (void __user *)arg, sizeof(state)))
+			return -EFAULT;
+		if (state == HSC_PM_DISABLE) {
+			if (test_and_set_bit(HSC_CH_WLINE, &channel->flags))
+				return -EINVAL;
+			ret = hsi_start_tx(channel->cl);
+		} else if (state == HSC_PM_ENABLE) {
+			if (!test_and_clear_bit(HSC_CH_WLINE, &channel->flags))
+				return -EINVAL;
+			ret = hsi_stop_tx(channel->cl);
+		} else {
+			ret = -EINVAL;
+		}
+		break;
+	case HSC_SEND_BREAK:
+		return hsc_break_send(channel->cl);
+	case HSC_SET_RX:
+		if (copy_from_user(&rxc, (void __user *)arg, sizeof(rxc)))
+			return -EFAULT;
+		return hsc_rx_set(channel->cl, &rxc);
+	case HSC_GET_RX:
+		hsc_rx_get(channel->cl, &rxc);
+		if (copy_to_user((void __user *)arg, &rxc, sizeof(rxc)))
+			return -EFAULT;
+		break;
+	case HSC_SET_TX:
+		if (copy_from_user(&txc, (void __user *)arg, sizeof(txc)))
+			return -EFAULT;
+		return hsc_tx_set(channel->cl, &txc);
+	case HSC_GET_TX:
+		hsc_tx_get(channel->cl, &txc);
+		if (copy_to_user((void __user *)arg, &txc, sizeof(txc)))
+			return -EFAULT;
+		break;
+	default:
+		return -ENOIOCTLCMD;
+	}
+
+	return ret;
+}
+
+static inline void __hsc_port_release(struct hsc_client_data *cl_data)
+{
+	BUG_ON(cl_data->usecnt == 0);
+
+	if (--cl_data->usecnt == 0) {
+		hsi_flush(cl_data->cl);
+		hsi_release_port(cl_data->cl);
+	}
+}
+
+static int hsc_open(struct inode *inode, struct file *file)
+{
+	struct hsc_client_data *cl_data;
+	struct hsc_channel *channel;
+	int ret = 0;
+
+	pr_debug("open, minor = %d\n", iminor(inode));
+
+	cl_data = container_of(inode->i_cdev, struct hsc_client_data, cdev);
+	mutex_lock(&cl_data->lock);
+	channel = cl_data->channels + (iminor(inode) & HSC_CH_MASK);
+
+	if (test_and_set_bit(HSC_CH_OPEN, &channel->flags)) {
+		ret = -EBUSY;
+		goto out;
+	}
+	/*
+	 * Check if we have already claimed the port associated to the HSI
+	 * client. If not then try to claim it, else increase its refcount
+	 */
+	if (cl_data->usecnt == 0) {
+		ret = hsi_claim_port(cl_data->cl, 0);
+		if (ret < 0)
+			goto out;
+		hsi_setup(cl_data->cl);
+	}
+	cl_data->usecnt++;
+
+	ret = hsc_msgs_alloc(channel);
+	if (ret < 0) {
+		__hsc_port_release(cl_data);
+		goto out;
+	}
+
+	file->private_data = channel;
+	mutex_unlock(&cl_data->lock);
+
+	return ret;
+out:
+	mutex_unlock(&cl_data->lock);
+
+	return ret;
+}
+
+static int hsc_release(struct inode *inode __maybe_unused, struct file *file)
+{
+	struct hsc_channel *channel = file->private_data;
+	struct hsc_client_data *cl_data = channel->cl_data;
+
+	mutex_lock(&cl_data->lock);
+	file->private_data = NULL;
+	if (test_and_clear_bit(HSC_CH_WLINE, &channel->flags))
+		hsi_stop_tx(channel->cl);
+	__hsc_port_release(cl_data);
+	hsc_reset_list(channel, &channel->rx_msgs_queue);
+	hsc_reset_list(channel, &channel->tx_msgs_queue);
+	hsc_reset_list(channel, &channel->free_msgs_list);
+	clear_bit(HSC_CH_READ, &channel->flags);
+	clear_bit(HSC_CH_WRITE, &channel->flags);
+	clear_bit(HSC_CH_OPEN, &channel->flags);
+	wake_up(&channel->rx_wait);
+	wake_up(&channel->tx_wait);
+	mutex_unlock(&cl_data->lock);
+
+	return 0;
+}
+
+static const struct file_operations hsc_fops = {
+	.owner		= THIS_MODULE,
+	.read		= hsc_read,
+	.write		= hsc_write,
+	.unlocked_ioctl	= hsc_ioctl,
+	.open		= hsc_open,
+	.release	= hsc_release,
+};
+
+static void hsc_channel_init(struct hsc_channel *channel)
+{
+	init_waitqueue_head(&channel->rx_wait);
+	init_waitqueue_head(&channel->tx_wait);
+	spin_lock_init(&channel->lock);
+	INIT_LIST_HEAD(&channel->free_msgs_list);
+	INIT_LIST_HEAD(&channel->rx_msgs_queue);
+	INIT_LIST_HEAD(&channel->tx_msgs_queue);
+}
+
+static int hsc_probe(struct device *dev)
+{
+	const char devname[] = "hsi_char";
+	struct hsc_client_data *cl_data;
+	struct hsc_channel *channel;
+	struct hsi_client *cl = to_hsi_client(dev);
+	unsigned int hsc_baseminor;
+	dev_t hsc_dev;
+	int ret;
+	int i;
+
+	cl_data = kzalloc(sizeof(*cl_data), GFP_KERNEL);
+	if (!cl_data)
+		return -ENOMEM;
+
+	hsc_baseminor = HSC_BASEMINOR(hsi_id(cl), hsi_port_id(cl));
+	if (!hsc_major) {
+		ret = alloc_chrdev_region(&hsc_dev, hsc_baseminor,
+						HSC_DEVS, devname);
+		if (ret == 0)
+			hsc_major = MAJOR(hsc_dev);
+	} else {
+		hsc_dev = MKDEV(hsc_major, hsc_baseminor);
+		ret = register_chrdev_region(hsc_dev, HSC_DEVS, devname);
+	}
+	if (ret < 0) {
+		dev_err(dev, "Device %s allocation failed %d\n",
+					hsc_major ? "minor" : "major", ret);
+		goto out1;
+	}
+	mutex_init(&cl_data->lock);
+	hsi_client_set_drvdata(cl, cl_data);
+	cdev_init(&cl_data->cdev, &hsc_fops);
+	cl_data->cdev.owner = THIS_MODULE;
+	cl_data->cl = cl;
+	for (i = 0, channel = cl_data->channels; i < HSC_DEVS; i++, channel++) {
+		hsc_channel_init(channel);
+		channel->ch = i;
+		channel->cl = cl;
+		channel->cl_data = cl_data;
+	}
+
+	/* 1 hsi client -> N char devices (one for each channel) */
+	ret = cdev_add(&cl_data->cdev, hsc_dev, HSC_DEVS);
+	if (ret) {
+		dev_err(dev, "Could not add char device %d\n", ret);
+		goto out2;
+	}
+
+	return 0;
+out2:
+	unregister_chrdev_region(hsc_dev, HSC_DEVS);
+out1:
+	kfree(cl_data);
+
+	return ret;
+}
+
+static int hsc_remove(struct device *dev)
+{
+	struct hsi_client *cl = to_hsi_client(dev);
+	struct hsc_client_data *cl_data = hsi_client_drvdata(cl);
+	dev_t hsc_dev = cl_data->cdev.dev;
+
+	cdev_del(&cl_data->cdev);
+	unregister_chrdev_region(hsc_dev, HSC_DEVS);
+	hsi_client_set_drvdata(cl, NULL);
+	kfree(cl_data);
+
+	return 0;
+}
+
+static struct hsi_client_driver hsc_driver = {
+	.driver = {
+		.name	= "hsi_char",
+		.owner	= THIS_MODULE,
+		.probe	= hsc_probe,
+		.remove	= hsc_remove,
+	},
+};
+
+static int __init hsc_init(void)
+{
+	int ret;
+
+	if ((max_data_size < 4) || (max_data_size > 0x10000) ||
+		(max_data_size & (max_data_size - 1))) {
+		pr_err("Invalid max read/write data size\n");
+		return -EINVAL;
+	}
+
+	ret = hsi_register_client_driver(&hsc_driver);
+	if (ret) {
+		pr_err("Error while registering HSI/SSI driver %d\n", ret);
+		return ret;
+	}
+
+	pr_info("HSI/SSI char device loaded\n");
+
+	return 0;
+}
+module_init(hsc_init);
+
+static void __exit hsc_exit(void)
+{
+	hsi_unregister_client_driver(&hsc_driver);
+	pr_info("HSI char device removed\n");
+}
+module_exit(hsc_exit);
+
+MODULE_AUTHOR("Andras Domokos <andras.domokos@nokia.com>");
+MODULE_ALIAS("hsi:hsi_char");
+MODULE_DESCRIPTION("HSI character device");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/hsi/clients/nokia-modem.c b/drivers/hsi/clients/nokia-modem.c
new file mode 100644
index 000000000..97ba59e60
--- /dev/null
+++ b/drivers/hsi/clients/nokia-modem.c
@@ -0,0 +1,298 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * nokia-modem.c
+ *
+ * HSI client driver for Nokia N900 modem.
+ *
+ * Copyright (C) 2014 Sebastian Reichel <sre@kernel.org>
+ */
+
+#include <linux/gpio/consumer.h>
+#include <linux/hsi/hsi.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/hsi/ssi_protocol.h>
+
+static unsigned int pm = 1;
+module_param(pm, int, 0400);
+MODULE_PARM_DESC(pm,
+	"Enable power management (0=disabled, 1=userland based [default])");
+
+struct nokia_modem_gpio {
+	struct gpio_desc	*gpio;
+	const char		*name;
+};
+
+struct nokia_modem_device {
+	struct tasklet_struct	nokia_modem_rst_ind_tasklet;
+	int			nokia_modem_rst_ind_irq;
+	struct device		*device;
+	struct nokia_modem_gpio	*gpios;
+	int			gpio_amount;
+	struct hsi_client	*ssi_protocol;
+	struct hsi_client	*cmt_speech;
+};
+
+static void do_nokia_modem_rst_ind_tasklet(unsigned long data)
+{
+	struct nokia_modem_device *modem = (struct nokia_modem_device *)data;
+
+	if (!modem)
+		return;
+
+	dev_info(modem->device, "CMT rst line change detected\n");
+
+	if (modem->ssi_protocol)
+		ssip_reset_event(modem->ssi_protocol);
+}
+
+static irqreturn_t nokia_modem_rst_ind_isr(int irq, void *data)
+{
+	struct nokia_modem_device *modem = (struct nokia_modem_device *)data;
+
+	tasklet_schedule(&modem->nokia_modem_rst_ind_tasklet);
+
+	return IRQ_HANDLED;
+}
+
+static void nokia_modem_gpio_unexport(struct device *dev)
+{
+	struct nokia_modem_device *modem = dev_get_drvdata(dev);
+	int i;
+
+	for (i = 0; i < modem->gpio_amount; i++) {
+		sysfs_remove_link(&dev->kobj, modem->gpios[i].name);
+		gpiod_unexport(modem->gpios[i].gpio);
+	}
+}
+
+static int nokia_modem_gpio_probe(struct device *dev)
+{
+	struct device_node *np = dev->of_node;
+	struct nokia_modem_device *modem = dev_get_drvdata(dev);
+	int gpio_count, gpio_name_count, i, err;
+
+	gpio_count = gpiod_count(dev, NULL);
+	if (gpio_count < 0) {
+		dev_err(dev, "missing gpios: %d\n", gpio_count);
+		return gpio_count;
+	}
+
+	gpio_name_count = of_property_count_strings(np, "gpio-names");
+
+	if (gpio_count != gpio_name_count) {
+		dev_err(dev, "number of gpios does not equal number of gpio names\n");
+		return -EINVAL;
+	}
+
+	modem->gpios = devm_kcalloc(dev, gpio_count, sizeof(*modem->gpios),
+				    GFP_KERNEL);
+	if (!modem->gpios)
+		return -ENOMEM;
+
+	modem->gpio_amount = gpio_count;
+
+	for (i = 0; i < gpio_count; i++) {
+		modem->gpios[i].gpio = devm_gpiod_get_index(dev, NULL, i,
+							    GPIOD_OUT_LOW);
+		if (IS_ERR(modem->gpios[i].gpio)) {
+			dev_err(dev, "Could not get gpio %d\n", i);
+			return PTR_ERR(modem->gpios[i].gpio);
+		}
+
+		err = of_property_read_string_index(np, "gpio-names", i,
+						&(modem->gpios[i].name));
+		if (err) {
+			dev_err(dev, "Could not get gpio name %d\n", i);
+			return err;
+		}
+
+		err = gpiod_export(modem->gpios[i].gpio, 0);
+		if (err)
+			return err;
+
+		err = gpiod_export_link(dev, modem->gpios[i].name,
+							modem->gpios[i].gpio);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static int nokia_modem_probe(struct device *dev)
+{
+	struct device_node *np;
+	struct nokia_modem_device *modem;
+	struct hsi_client *cl = to_hsi_client(dev);
+	struct hsi_port *port = hsi_get_port(cl);
+	int irq, pflags, err;
+	struct hsi_board_info ssip;
+	struct hsi_board_info cmtspeech;
+
+	np = dev->of_node;
+	if (!np) {
+		dev_err(dev, "device tree node not found\n");
+		return -ENXIO;
+	}
+
+	modem = devm_kzalloc(dev, sizeof(*modem), GFP_KERNEL);
+	if (!modem)
+		return -ENOMEM;
+
+	dev_set_drvdata(dev, modem);
+	modem->device = dev;
+
+	irq = irq_of_parse_and_map(np, 0);
+	if (!irq) {
+		dev_err(dev, "Invalid rst_ind interrupt (%d)\n", irq);
+		return -EINVAL;
+	}
+	modem->nokia_modem_rst_ind_irq = irq;
+	pflags = irq_get_trigger_type(irq);
+
+	tasklet_init(&modem->nokia_modem_rst_ind_tasklet,
+			do_nokia_modem_rst_ind_tasklet, (unsigned long)modem);
+	err = devm_request_irq(dev, irq, nokia_modem_rst_ind_isr,
+				pflags, "modem_rst_ind", modem);
+	if (err < 0) {
+		dev_err(dev, "Request rst_ind irq(%d) failed (flags %d)\n",
+								irq, pflags);
+		return err;
+	}
+	enable_irq_wake(irq);
+
+	if (pm) {
+		err = nokia_modem_gpio_probe(dev);
+		if (err < 0) {
+			dev_err(dev, "Could not probe GPIOs\n");
+			goto error1;
+		}
+	}
+
+	ssip.name = "ssi-protocol";
+	ssip.tx_cfg = cl->tx_cfg;
+	ssip.rx_cfg = cl->rx_cfg;
+	ssip.platform_data = NULL;
+	ssip.archdata = NULL;
+
+	modem->ssi_protocol = hsi_new_client(port, &ssip);
+	if (!modem->ssi_protocol) {
+		dev_err(dev, "Could not register ssi-protocol device\n");
+		err = -ENOMEM;
+		goto error2;
+	}
+
+	err = device_attach(&modem->ssi_protocol->device);
+	if (err == 0) {
+		dev_dbg(dev, "Missing ssi-protocol driver\n");
+		err = -EPROBE_DEFER;
+		goto error3;
+	} else if (err < 0) {
+		dev_err(dev, "Could not load ssi-protocol driver (%d)\n", err);
+		goto error3;
+	}
+
+	cmtspeech.name = "cmt-speech";
+	cmtspeech.tx_cfg = cl->tx_cfg;
+	cmtspeech.rx_cfg = cl->rx_cfg;
+	cmtspeech.platform_data = NULL;
+	cmtspeech.archdata = NULL;
+
+	modem->cmt_speech = hsi_new_client(port, &cmtspeech);
+	if (!modem->cmt_speech) {
+		dev_err(dev, "Could not register cmt-speech device\n");
+		err = -ENOMEM;
+		goto error3;
+	}
+
+	err = device_attach(&modem->cmt_speech->device);
+	if (err == 0) {
+		dev_dbg(dev, "Missing cmt-speech driver\n");
+		err = -EPROBE_DEFER;
+		goto error4;
+	} else if (err < 0) {
+		dev_err(dev, "Could not load cmt-speech driver (%d)\n", err);
+		goto error4;
+	}
+
+	dev_info(dev, "Registered Nokia HSI modem\n");
+
+	return 0;
+
+error4:
+	hsi_remove_client(&modem->cmt_speech->device, NULL);
+error3:
+	hsi_remove_client(&modem->ssi_protocol->device, NULL);
+error2:
+	nokia_modem_gpio_unexport(dev);
+error1:
+	disable_irq_wake(modem->nokia_modem_rst_ind_irq);
+	tasklet_kill(&modem->nokia_modem_rst_ind_tasklet);
+
+	return err;
+}
+
+static int nokia_modem_remove(struct device *dev)
+{
+	struct nokia_modem_device *modem = dev_get_drvdata(dev);
+
+	if (!modem)
+		return 0;
+
+	if (modem->cmt_speech) {
+		hsi_remove_client(&modem->cmt_speech->device, NULL);
+		modem->cmt_speech = NULL;
+	}
+
+	if (modem->ssi_protocol) {
+		hsi_remove_client(&modem->ssi_protocol->device, NULL);
+		modem->ssi_protocol = NULL;
+	}
+
+	nokia_modem_gpio_unexport(dev);
+	dev_set_drvdata(dev, NULL);
+	disable_irq_wake(modem->nokia_modem_rst_ind_irq);
+	tasklet_kill(&modem->nokia_modem_rst_ind_tasklet);
+
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id nokia_modem_of_match[] = {
+	{ .compatible = "nokia,n900-modem", },
+	{ .compatible = "nokia,n950-modem", },
+	{ .compatible = "nokia,n9-modem", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, nokia_modem_of_match);
+#endif
+
+static struct hsi_client_driver nokia_modem_driver = {
+	.driver = {
+		.name	= "nokia-modem",
+		.owner	= THIS_MODULE,
+		.probe	= nokia_modem_probe,
+		.remove	= nokia_modem_remove,
+		.of_match_table = of_match_ptr(nokia_modem_of_match),
+	},
+};
+
+static int __init nokia_modem_init(void)
+{
+	return hsi_register_client_driver(&nokia_modem_driver);
+}
+module_init(nokia_modem_init);
+
+static void __exit nokia_modem_exit(void)
+{
+	hsi_unregister_client_driver(&nokia_modem_driver);
+}
+module_exit(nokia_modem_exit);
+
+MODULE_ALIAS("hsi:nokia-modem");
+MODULE_AUTHOR("Sebastian Reichel <sre@kernel.org>");
+MODULE_DESCRIPTION("HSI driver module for Nokia N900 Modem");
+MODULE_LICENSE("GPL");
diff --git a/drivers/hsi/clients/ssi_protocol.c b/drivers/hsi/clients/ssi_protocol.c
new file mode 100644
index 000000000..274ad8443
--- /dev/null
+++ b/drivers/hsi/clients/ssi_protocol.c
@@ -0,0 +1,1193 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ssi_protocol.c
+ *
+ * Implementation of the SSI McSAAB improved protocol.
+ *
+ * Copyright (C) 2010 Nokia Corporation. All rights reserved.
+ * Copyright (C) 2013 Sebastian Reichel <sre@kernel.org>
+ *
+ * Contact: Carlos Chinea <carlos.chinea@nokia.com>
+ */
+
+#include <linux/atomic.h>
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/gpio.h>
+#include <linux/if_ether.h>
+#include <linux/if_arp.h>
+#include <linux/if_phonet.h>
+#include <linux/init.h>
+#include <linux/irq.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/notifier.h>
+#include <linux/scatterlist.h>
+#include <linux/skbuff.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/timer.h>
+#include <linux/hsi/hsi.h>
+#include <linux/hsi/ssi_protocol.h>
+
+void ssi_waketest(struct hsi_client *cl, unsigned int enable);
+
+#define SSIP_TXQUEUE_LEN	100
+#define SSIP_MAX_MTU		65535
+#define SSIP_DEFAULT_MTU	4000
+#define PN_MEDIA_SOS		21
+#define SSIP_MIN_PN_HDR		6	/* FIXME: Revisit */
+#define SSIP_WDTOUT		2000	/* FIXME: has to be 500 msecs */
+#define SSIP_KATOUT		15	/* 15 msecs */
+#define SSIP_MAX_CMDS		5 /* Number of pre-allocated commands buffers */
+#define SSIP_BYTES_TO_FRAMES(x) ((((x) - 1) >> 2) + 1)
+#define SSIP_CMT_LOADER_SYNC	0x11223344
+/*
+ * SSI protocol command definitions
+ */
+#define SSIP_COMMAND(data)	((data) >> 28)
+#define SSIP_PAYLOAD(data)	((data) & 0xfffffff)
+/* Commands */
+#define SSIP_SW_BREAK		0
+#define SSIP_BOOTINFO_REQ	1
+#define SSIP_BOOTINFO_RESP	2
+#define SSIP_WAKETEST_RESULT	3
+#define SSIP_START_TRANS	4
+#define SSIP_READY		5
+/* Payloads */
+#define SSIP_DATA_VERSION(data)	((data) & 0xff)
+#define SSIP_LOCAL_VERID	1
+#define SSIP_WAKETEST_OK	0
+#define SSIP_WAKETEST_FAILED	1
+#define SSIP_PDU_LENGTH(data)	(((data) >> 8) & 0xffff)
+#define SSIP_MSG_ID(data)	((data) & 0xff)
+/* Generic Command */
+#define SSIP_CMD(cmd, payload)	(((cmd) << 28) | ((payload) & 0xfffffff))
+/* Commands for the control channel */
+#define SSIP_BOOTINFO_REQ_CMD(ver) \
+		SSIP_CMD(SSIP_BOOTINFO_REQ, SSIP_DATA_VERSION(ver))
+#define SSIP_BOOTINFO_RESP_CMD(ver) \
+		SSIP_CMD(SSIP_BOOTINFO_RESP, SSIP_DATA_VERSION(ver))
+#define SSIP_START_TRANS_CMD(pdulen, id) \
+		SSIP_CMD(SSIP_START_TRANS, (((pdulen) << 8) | SSIP_MSG_ID(id)))
+#define SSIP_READY_CMD		SSIP_CMD(SSIP_READY, 0)
+#define SSIP_SWBREAK_CMD	SSIP_CMD(SSIP_SW_BREAK, 0)
+
+#define SSIP_WAKETEST_FLAG 0
+
+/* Main state machine states */
+enum {
+	INIT,
+	HANDSHAKE,
+	ACTIVE,
+};
+
+/* Send state machine states */
+enum {
+	SEND_IDLE,
+	WAIT4READY,
+	SEND_READY,
+	SENDING,
+	SENDING_SWBREAK,
+};
+
+/* Receive state machine states */
+enum {
+	RECV_IDLE,
+	RECV_READY,
+	RECEIVING,
+};
+
+/**
+ * struct ssi_protocol - SSI protocol (McSAAB) data
+ * @main_state: Main state machine
+ * @send_state: TX state machine
+ * @recv_state: RX state machine
+ * @flags: Flags, currently only used to follow wake line test
+ * @rxid: RX data id
+ * @txid: TX data id
+ * @txqueue_len: TX queue length
+ * @tx_wd: TX watchdog
+ * @rx_wd: RX watchdog
+ * @keep_alive: Workaround for SSI HW bug
+ * @lock: To serialize access to this struct
+ * @netdev: Phonet network device
+ * @txqueue: TX data queue
+ * @cmdqueue: Queue of free commands
+ * @cl: HSI client own reference
+ * @link: Link for ssip_list
+ * @tx_usecount: Refcount to keep track the slaves that use the wake line
+ * @channel_id_cmd: HSI channel id for command stream
+ * @channel_id_data: HSI channel id for data stream
+ */
+struct ssi_protocol {
+	unsigned int		main_state;
+	unsigned int		send_state;
+	unsigned int		recv_state;
+	unsigned long		flags;
+	u8			rxid;
+	u8			txid;
+	unsigned int		txqueue_len;
+	struct timer_list	tx_wd;
+	struct timer_list	rx_wd;
+	struct timer_list	keep_alive; /* wake-up workaround */
+	spinlock_t		lock;
+	struct net_device	*netdev;
+	struct list_head	txqueue;
+	struct list_head	cmdqueue;
+	struct work_struct	work;
+	struct hsi_client	*cl;
+	struct list_head	link;
+	atomic_t		tx_usecnt;
+	int			channel_id_cmd;
+	int			channel_id_data;
+};
+
+/* List of ssi protocol instances */
+static LIST_HEAD(ssip_list);
+
+static void ssip_rxcmd_complete(struct hsi_msg *msg);
+
+static inline void ssip_set_cmd(struct hsi_msg *msg, u32 cmd)
+{
+	u32 *data;
+
+	data = sg_virt(msg->sgt.sgl);
+	*data = cmd;
+}
+
+static inline u32 ssip_get_cmd(struct hsi_msg *msg)
+{
+	u32 *data;
+
+	data = sg_virt(msg->sgt.sgl);
+
+	return *data;
+}
+
+static void ssip_skb_to_msg(struct sk_buff *skb, struct hsi_msg *msg)
+{
+	skb_frag_t *frag;
+	struct scatterlist *sg;
+	int i;
+
+	BUG_ON(msg->sgt.nents != (unsigned int)(skb_shinfo(skb)->nr_frags + 1));
+
+	sg = msg->sgt.sgl;
+	sg_set_buf(sg, skb->data, skb_headlen(skb));
+	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+		sg = sg_next(sg);
+		BUG_ON(!sg);
+		frag = &skb_shinfo(skb)->frags[i];
+		sg_set_page(sg, skb_frag_page(frag), skb_frag_size(frag),
+				skb_frag_off(frag));
+	}
+}
+
+static void ssip_free_data(struct hsi_msg *msg)
+{
+	struct sk_buff *skb;
+
+	skb = msg->context;
+	pr_debug("free data: msg %p context %p skb %p\n", msg, msg->context,
+								skb);
+	msg->destructor = NULL;
+	dev_kfree_skb(skb);
+	hsi_free_msg(msg);
+}
+
+static struct hsi_msg *ssip_alloc_data(struct ssi_protocol *ssi,
+					struct sk_buff *skb, gfp_t flags)
+{
+	struct hsi_msg *msg;
+
+	msg = hsi_alloc_msg(skb_shinfo(skb)->nr_frags + 1, flags);
+	if (!msg)
+		return NULL;
+	ssip_skb_to_msg(skb, msg);
+	msg->destructor = ssip_free_data;
+	msg->channel = ssi->channel_id_data;
+	msg->context = skb;
+
+	return msg;
+}
+
+static inline void ssip_release_cmd(struct hsi_msg *msg)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(msg->cl);
+
+	dev_dbg(&msg->cl->device, "Release cmd 0x%08x\n", ssip_get_cmd(msg));
+	spin_lock_bh(&ssi->lock);
+	list_add_tail(&msg->link, &ssi->cmdqueue);
+	spin_unlock_bh(&ssi->lock);
+}
+
+static struct hsi_msg *ssip_claim_cmd(struct ssi_protocol *ssi)
+{
+	struct hsi_msg *msg;
+
+	BUG_ON(list_empty(&ssi->cmdqueue));
+
+	spin_lock_bh(&ssi->lock);
+	msg = list_first_entry(&ssi->cmdqueue, struct hsi_msg, link);
+	list_del(&msg->link);
+	spin_unlock_bh(&ssi->lock);
+	msg->destructor = ssip_release_cmd;
+
+	return msg;
+}
+
+static void ssip_free_cmds(struct ssi_protocol *ssi)
+{
+	struct hsi_msg *msg, *tmp;
+
+	list_for_each_entry_safe(msg, tmp, &ssi->cmdqueue, link) {
+		list_del(&msg->link);
+		msg->destructor = NULL;
+		kfree(sg_virt(msg->sgt.sgl));
+		hsi_free_msg(msg);
+	}
+}
+
+static int ssip_alloc_cmds(struct ssi_protocol *ssi)
+{
+	struct hsi_msg *msg;
+	u32 *buf;
+	unsigned int i;
+
+	for (i = 0; i < SSIP_MAX_CMDS; i++) {
+		msg = hsi_alloc_msg(1, GFP_KERNEL);
+		if (!msg)
+			goto out;
+		buf = kmalloc(sizeof(*buf), GFP_KERNEL);
+		if (!buf) {
+			hsi_free_msg(msg);
+			goto out;
+		}
+		sg_init_one(msg->sgt.sgl, buf, sizeof(*buf));
+		msg->channel = ssi->channel_id_cmd;
+		list_add_tail(&msg->link, &ssi->cmdqueue);
+	}
+
+	return 0;
+out:
+	ssip_free_cmds(ssi);
+
+	return -ENOMEM;
+}
+
+static void ssip_set_rxstate(struct ssi_protocol *ssi, unsigned int state)
+{
+	ssi->recv_state = state;
+	switch (state) {
+	case RECV_IDLE:
+		del_timer(&ssi->rx_wd);
+		if (ssi->send_state == SEND_IDLE)
+			del_timer(&ssi->keep_alive);
+		break;
+	case RECV_READY:
+		/* CMT speech workaround */
+		if (atomic_read(&ssi->tx_usecnt))
+			break;
+		fallthrough;
+	case RECEIVING:
+		mod_timer(&ssi->keep_alive, jiffies +
+						msecs_to_jiffies(SSIP_KATOUT));
+		mod_timer(&ssi->rx_wd, jiffies + msecs_to_jiffies(SSIP_WDTOUT));
+		break;
+	default:
+		break;
+	}
+}
+
+static void ssip_set_txstate(struct ssi_protocol *ssi, unsigned int state)
+{
+	ssi->send_state = state;
+	switch (state) {
+	case SEND_IDLE:
+	case SEND_READY:
+		del_timer(&ssi->tx_wd);
+		if (ssi->recv_state == RECV_IDLE)
+			del_timer(&ssi->keep_alive);
+		break;
+	case WAIT4READY:
+	case SENDING:
+	case SENDING_SWBREAK:
+		mod_timer(&ssi->keep_alive,
+				jiffies + msecs_to_jiffies(SSIP_KATOUT));
+		mod_timer(&ssi->tx_wd, jiffies + msecs_to_jiffies(SSIP_WDTOUT));
+		break;
+	default:
+		break;
+	}
+}
+
+struct hsi_client *ssip_slave_get_master(struct hsi_client *slave)
+{
+	struct hsi_client *master = ERR_PTR(-ENODEV);
+	struct ssi_protocol *ssi;
+
+	list_for_each_entry(ssi, &ssip_list, link)
+		if (slave->device.parent == ssi->cl->device.parent) {
+			master = ssi->cl;
+			break;
+		}
+
+	return master;
+}
+EXPORT_SYMBOL_GPL(ssip_slave_get_master);
+
+int ssip_slave_start_tx(struct hsi_client *master)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(master);
+
+	dev_dbg(&master->device, "start TX %d\n", atomic_read(&ssi->tx_usecnt));
+	spin_lock_bh(&ssi->lock);
+	if (ssi->send_state == SEND_IDLE) {
+		ssip_set_txstate(ssi, WAIT4READY);
+		hsi_start_tx(master);
+	}
+	spin_unlock_bh(&ssi->lock);
+	atomic_inc(&ssi->tx_usecnt);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(ssip_slave_start_tx);
+
+int ssip_slave_stop_tx(struct hsi_client *master)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(master);
+
+	WARN_ON_ONCE(atomic_read(&ssi->tx_usecnt) == 0);
+
+	if (atomic_dec_and_test(&ssi->tx_usecnt)) {
+		spin_lock_bh(&ssi->lock);
+		if ((ssi->send_state == SEND_READY) ||
+			(ssi->send_state == WAIT4READY)) {
+			ssip_set_txstate(ssi, SEND_IDLE);
+			hsi_stop_tx(master);
+		}
+		spin_unlock_bh(&ssi->lock);
+	}
+	dev_dbg(&master->device, "stop TX %d\n", atomic_read(&ssi->tx_usecnt));
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(ssip_slave_stop_tx);
+
+int ssip_slave_running(struct hsi_client *master)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(master);
+	return netif_running(ssi->netdev);
+}
+EXPORT_SYMBOL_GPL(ssip_slave_running);
+
+static void ssip_reset(struct hsi_client *cl)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+	struct list_head *head, *tmp;
+	struct hsi_msg *msg;
+
+	if (netif_running(ssi->netdev))
+		netif_carrier_off(ssi->netdev);
+	hsi_flush(cl);
+	spin_lock_bh(&ssi->lock);
+	if (ssi->send_state != SEND_IDLE)
+		hsi_stop_tx(cl);
+	spin_unlock_bh(&ssi->lock);
+	if (test_and_clear_bit(SSIP_WAKETEST_FLAG, &ssi->flags))
+		ssi_waketest(cl, 0); /* FIXME: To be removed */
+	spin_lock_bh(&ssi->lock);
+	del_timer(&ssi->rx_wd);
+	del_timer(&ssi->tx_wd);
+	del_timer(&ssi->keep_alive);
+	ssi->main_state = 0;
+	ssi->send_state = 0;
+	ssi->recv_state = 0;
+	ssi->flags = 0;
+	ssi->rxid = 0;
+	ssi->txid = 0;
+	list_for_each_safe(head, tmp, &ssi->txqueue) {
+		msg = list_entry(head, struct hsi_msg, link);
+		dev_dbg(&cl->device, "Pending TX data\n");
+		list_del(head);
+		ssip_free_data(msg);
+	}
+	ssi->txqueue_len = 0;
+	spin_unlock_bh(&ssi->lock);
+}
+
+static void ssip_dump_state(struct hsi_client *cl)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+	struct hsi_msg *msg;
+
+	spin_lock_bh(&ssi->lock);
+	dev_err(&cl->device, "Main state: %d\n", ssi->main_state);
+	dev_err(&cl->device, "Recv state: %d\n", ssi->recv_state);
+	dev_err(&cl->device, "Send state: %d\n", ssi->send_state);
+	dev_err(&cl->device, "CMT %s\n", (ssi->main_state == ACTIVE) ?
+							"Online" : "Offline");
+	dev_err(&cl->device, "Wake test %d\n",
+				test_bit(SSIP_WAKETEST_FLAG, &ssi->flags));
+	dev_err(&cl->device, "Data RX id: %d\n", ssi->rxid);
+	dev_err(&cl->device, "Data TX id: %d\n", ssi->txid);
+
+	list_for_each_entry(msg, &ssi->txqueue, link)
+		dev_err(&cl->device, "pending TX data (%p)\n", msg);
+	spin_unlock_bh(&ssi->lock);
+}
+
+static void ssip_error(struct hsi_client *cl)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+	struct hsi_msg *msg;
+
+	ssip_dump_state(cl);
+	ssip_reset(cl);
+	msg = ssip_claim_cmd(ssi);
+	msg->complete = ssip_rxcmd_complete;
+	hsi_async_read(cl, msg);
+}
+
+static void ssip_keep_alive(struct timer_list *t)
+{
+	struct ssi_protocol *ssi = from_timer(ssi, t, keep_alive);
+	struct hsi_client *cl = ssi->cl;
+
+	dev_dbg(&cl->device, "Keep alive kick in: m(%d) r(%d) s(%d)\n",
+		ssi->main_state, ssi->recv_state, ssi->send_state);
+
+	spin_lock(&ssi->lock);
+	if (ssi->recv_state == RECV_IDLE)
+		switch (ssi->send_state) {
+		case SEND_READY:
+			if (atomic_read(&ssi->tx_usecnt) == 0)
+				break;
+			fallthrough;
+			/*
+			 * Workaround for cmt-speech in that case
+			 * we relay on audio timers.
+			 */
+		case SEND_IDLE:
+			spin_unlock(&ssi->lock);
+			return;
+		}
+	mod_timer(&ssi->keep_alive, jiffies + msecs_to_jiffies(SSIP_KATOUT));
+	spin_unlock(&ssi->lock);
+}
+
+static void ssip_rx_wd(struct timer_list *t)
+{
+	struct ssi_protocol *ssi = from_timer(ssi, t, rx_wd);
+	struct hsi_client *cl = ssi->cl;
+
+	dev_err(&cl->device, "Watchdog triggered\n");
+	ssip_error(cl);
+}
+
+static void ssip_tx_wd(struct timer_list *t)
+{
+	struct ssi_protocol *ssi = from_timer(ssi, t, tx_wd);
+	struct hsi_client *cl = ssi->cl;
+
+	dev_err(&cl->device, "Watchdog triggered\n");
+	ssip_error(cl);
+}
+
+static void ssip_send_bootinfo_req_cmd(struct hsi_client *cl)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+	struct hsi_msg *msg;
+
+	dev_dbg(&cl->device, "Issuing BOOT INFO REQ command\n");
+	msg = ssip_claim_cmd(ssi);
+	ssip_set_cmd(msg, SSIP_BOOTINFO_REQ_CMD(SSIP_LOCAL_VERID));
+	msg->complete = ssip_release_cmd;
+	hsi_async_write(cl, msg);
+	dev_dbg(&cl->device, "Issuing RX command\n");
+	msg = ssip_claim_cmd(ssi);
+	msg->complete = ssip_rxcmd_complete;
+	hsi_async_read(cl, msg);
+}
+
+static void ssip_start_rx(struct hsi_client *cl)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+	struct hsi_msg *msg;
+
+	dev_dbg(&cl->device, "RX start M(%d) R(%d)\n", ssi->main_state,
+						ssi->recv_state);
+	spin_lock_bh(&ssi->lock);
+	/*
+	 * We can have two UP events in a row due to a short low
+	 * high transition. Therefore we need to ignore the sencond UP event.
+	 */
+	if ((ssi->main_state != ACTIVE) || (ssi->recv_state == RECV_READY)) {
+		spin_unlock_bh(&ssi->lock);
+		return;
+	}
+	ssip_set_rxstate(ssi, RECV_READY);
+	spin_unlock_bh(&ssi->lock);
+
+	msg = ssip_claim_cmd(ssi);
+	ssip_set_cmd(msg, SSIP_READY_CMD);
+	msg->complete = ssip_release_cmd;
+	dev_dbg(&cl->device, "Send READY\n");
+	hsi_async_write(cl, msg);
+}
+
+static void ssip_stop_rx(struct hsi_client *cl)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+
+	dev_dbg(&cl->device, "RX stop M(%d)\n", ssi->main_state);
+	spin_lock_bh(&ssi->lock);
+	if (likely(ssi->main_state == ACTIVE))
+		ssip_set_rxstate(ssi, RECV_IDLE);
+	spin_unlock_bh(&ssi->lock);
+}
+
+static void ssip_free_strans(struct hsi_msg *msg)
+{
+	ssip_free_data(msg->context);
+	ssip_release_cmd(msg);
+}
+
+static void ssip_strans_complete(struct hsi_msg *msg)
+{
+	struct hsi_client *cl = msg->cl;
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+	struct hsi_msg *data;
+
+	data = msg->context;
+	ssip_release_cmd(msg);
+	spin_lock_bh(&ssi->lock);
+	ssip_set_txstate(ssi, SENDING);
+	spin_unlock_bh(&ssi->lock);
+	hsi_async_write(cl, data);
+}
+
+static int ssip_xmit(struct hsi_client *cl)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+	struct hsi_msg *msg, *dmsg;
+	struct sk_buff *skb;
+
+	spin_lock_bh(&ssi->lock);
+	if (list_empty(&ssi->txqueue)) {
+		spin_unlock_bh(&ssi->lock);
+		return 0;
+	}
+	dmsg = list_first_entry(&ssi->txqueue, struct hsi_msg, link);
+	list_del(&dmsg->link);
+	ssi->txqueue_len--;
+	spin_unlock_bh(&ssi->lock);
+
+	msg = ssip_claim_cmd(ssi);
+	skb = dmsg->context;
+	msg->context = dmsg;
+	msg->complete = ssip_strans_complete;
+	msg->destructor = ssip_free_strans;
+
+	spin_lock_bh(&ssi->lock);
+	ssip_set_cmd(msg, SSIP_START_TRANS_CMD(SSIP_BYTES_TO_FRAMES(skb->len),
+								ssi->txid));
+	ssi->txid++;
+	ssip_set_txstate(ssi, SENDING);
+	spin_unlock_bh(&ssi->lock);
+
+	dev_dbg(&cl->device, "Send STRANS (%d frames)\n",
+						SSIP_BYTES_TO_FRAMES(skb->len));
+
+	return hsi_async_write(cl, msg);
+}
+
+/* In soft IRQ context */
+static void ssip_pn_rx(struct sk_buff *skb)
+{
+	struct net_device *dev = skb->dev;
+
+	if (unlikely(!netif_running(dev))) {
+		dev_dbg(&dev->dev, "Drop RX packet\n");
+		dev->stats.rx_dropped++;
+		dev_kfree_skb(skb);
+		return;
+	}
+	if (unlikely(!pskb_may_pull(skb, SSIP_MIN_PN_HDR))) {
+		dev_dbg(&dev->dev, "Error drop RX packet\n");
+		dev->stats.rx_errors++;
+		dev->stats.rx_length_errors++;
+		dev_kfree_skb(skb);
+		return;
+	}
+	dev->stats.rx_packets++;
+	dev->stats.rx_bytes += skb->len;
+
+	/* length field is exchanged in network byte order */
+	((u16 *)skb->data)[2] = ntohs(((u16 *)skb->data)[2]);
+	dev_dbg(&dev->dev, "RX length fixed (%04x -> %u)\n",
+			((u16 *)skb->data)[2], ntohs(((u16 *)skb->data)[2]));
+
+	skb->protocol = htons(ETH_P_PHONET);
+	skb_reset_mac_header(skb);
+	__skb_pull(skb, 1);
+	netif_rx(skb);
+}
+
+static void ssip_rx_data_complete(struct hsi_msg *msg)
+{
+	struct hsi_client *cl = msg->cl;
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+	struct sk_buff *skb;
+
+	if (msg->status == HSI_STATUS_ERROR) {
+		dev_err(&cl->device, "RX data error\n");
+		ssip_free_data(msg);
+		ssip_error(cl);
+		return;
+	}
+	del_timer(&ssi->rx_wd); /* FIXME: Revisit */
+	skb = msg->context;
+	ssip_pn_rx(skb);
+	hsi_free_msg(msg);
+}
+
+static void ssip_rx_bootinforeq(struct hsi_client *cl, u32 cmd)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+	struct hsi_msg *msg;
+
+	/* Workaroud: Ignore CMT Loader message leftover */
+	if (cmd == SSIP_CMT_LOADER_SYNC)
+		return;
+
+	switch (ssi->main_state) {
+	case ACTIVE:
+		dev_err(&cl->device, "Boot info req on active state\n");
+		ssip_error(cl);
+		fallthrough;
+	case INIT:
+	case HANDSHAKE:
+		spin_lock_bh(&ssi->lock);
+		ssi->main_state = HANDSHAKE;
+		spin_unlock_bh(&ssi->lock);
+
+		if (!test_and_set_bit(SSIP_WAKETEST_FLAG, &ssi->flags))
+			ssi_waketest(cl, 1); /* FIXME: To be removed */
+
+		spin_lock_bh(&ssi->lock);
+		/* Start boot handshake watchdog */
+		mod_timer(&ssi->tx_wd, jiffies + msecs_to_jiffies(SSIP_WDTOUT));
+		spin_unlock_bh(&ssi->lock);
+		dev_dbg(&cl->device, "Send BOOTINFO_RESP\n");
+		if (SSIP_DATA_VERSION(cmd) != SSIP_LOCAL_VERID)
+			dev_warn(&cl->device, "boot info req verid mismatch\n");
+		msg = ssip_claim_cmd(ssi);
+		ssip_set_cmd(msg, SSIP_BOOTINFO_RESP_CMD(SSIP_LOCAL_VERID));
+		msg->complete = ssip_release_cmd;
+		hsi_async_write(cl, msg);
+		break;
+	default:
+		dev_dbg(&cl->device, "Wrong state M(%d)\n", ssi->main_state);
+		break;
+	}
+}
+
+static void ssip_rx_bootinforesp(struct hsi_client *cl, u32 cmd)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+
+	if (SSIP_DATA_VERSION(cmd) != SSIP_LOCAL_VERID)
+		dev_warn(&cl->device, "boot info resp verid mismatch\n");
+
+	spin_lock_bh(&ssi->lock);
+	if (ssi->main_state != ACTIVE)
+		/* Use tx_wd as a boot watchdog in non ACTIVE state */
+		mod_timer(&ssi->tx_wd, jiffies + msecs_to_jiffies(SSIP_WDTOUT));
+	else
+		dev_dbg(&cl->device, "boot info resp ignored M(%d)\n",
+							ssi->main_state);
+	spin_unlock_bh(&ssi->lock);
+}
+
+static void ssip_rx_waketest(struct hsi_client *cl, u32 cmd)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+	unsigned int wkres = SSIP_PAYLOAD(cmd);
+
+	spin_lock_bh(&ssi->lock);
+	if (ssi->main_state != HANDSHAKE) {
+		dev_dbg(&cl->device, "wake lines test ignored M(%d)\n",
+							ssi->main_state);
+		spin_unlock_bh(&ssi->lock);
+		return;
+	}
+	spin_unlock_bh(&ssi->lock);
+
+	if (test_and_clear_bit(SSIP_WAKETEST_FLAG, &ssi->flags))
+		ssi_waketest(cl, 0); /* FIXME: To be removed */
+
+	spin_lock_bh(&ssi->lock);
+	ssi->main_state = ACTIVE;
+	del_timer(&ssi->tx_wd); /* Stop boot handshake timer */
+	spin_unlock_bh(&ssi->lock);
+
+	dev_notice(&cl->device, "WAKELINES TEST %s\n",
+				wkres & SSIP_WAKETEST_FAILED ? "FAILED" : "OK");
+	if (wkres & SSIP_WAKETEST_FAILED) {
+		ssip_error(cl);
+		return;
+	}
+	dev_dbg(&cl->device, "CMT is ONLINE\n");
+	netif_wake_queue(ssi->netdev);
+	netif_carrier_on(ssi->netdev);
+}
+
+static void ssip_rx_ready(struct hsi_client *cl)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+
+	spin_lock_bh(&ssi->lock);
+	if (unlikely(ssi->main_state != ACTIVE)) {
+		dev_dbg(&cl->device, "READY on wrong state: S(%d) M(%d)\n",
+					ssi->send_state, ssi->main_state);
+		spin_unlock_bh(&ssi->lock);
+		return;
+	}
+	if (ssi->send_state != WAIT4READY) {
+		dev_dbg(&cl->device, "Ignore spurious READY command\n");
+		spin_unlock_bh(&ssi->lock);
+		return;
+	}
+	ssip_set_txstate(ssi, SEND_READY);
+	spin_unlock_bh(&ssi->lock);
+	ssip_xmit(cl);
+}
+
+static void ssip_rx_strans(struct hsi_client *cl, u32 cmd)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+	struct sk_buff *skb;
+	struct hsi_msg *msg;
+	int len = SSIP_PDU_LENGTH(cmd);
+
+	dev_dbg(&cl->device, "RX strans: %d frames\n", len);
+	spin_lock_bh(&ssi->lock);
+	if (unlikely(ssi->main_state != ACTIVE)) {
+		dev_err(&cl->device, "START TRANS wrong state: S(%d) M(%d)\n",
+					ssi->send_state, ssi->main_state);
+		spin_unlock_bh(&ssi->lock);
+		return;
+	}
+	ssip_set_rxstate(ssi, RECEIVING);
+	if (unlikely(SSIP_MSG_ID(cmd) != ssi->rxid)) {
+		dev_err(&cl->device, "START TRANS id %d expected %d\n",
+					SSIP_MSG_ID(cmd), ssi->rxid);
+		spin_unlock_bh(&ssi->lock);
+		goto out1;
+	}
+	ssi->rxid++;
+	spin_unlock_bh(&ssi->lock);
+	skb = netdev_alloc_skb(ssi->netdev, len * 4);
+	if (unlikely(!skb)) {
+		dev_err(&cl->device, "No memory for rx skb\n");
+		goto out1;
+	}
+	skb_put(skb, len * 4);
+	msg = ssip_alloc_data(ssi, skb, GFP_ATOMIC);
+	if (unlikely(!msg)) {
+		dev_err(&cl->device, "No memory for RX data msg\n");
+		goto out2;
+	}
+	msg->complete = ssip_rx_data_complete;
+	hsi_async_read(cl, msg);
+
+	return;
+out2:
+	dev_kfree_skb(skb);
+out1:
+	ssip_error(cl);
+}
+
+static void ssip_rxcmd_complete(struct hsi_msg *msg)
+{
+	struct hsi_client *cl = msg->cl;
+	u32 cmd = ssip_get_cmd(msg);
+	unsigned int cmdid = SSIP_COMMAND(cmd);
+
+	if (msg->status == HSI_STATUS_ERROR) {
+		dev_err(&cl->device, "RX error detected\n");
+		ssip_release_cmd(msg);
+		ssip_error(cl);
+		return;
+	}
+	hsi_async_read(cl, msg);
+	dev_dbg(&cl->device, "RX cmd: 0x%08x\n", cmd);
+	switch (cmdid) {
+	case SSIP_SW_BREAK:
+		/* Ignored */
+		break;
+	case SSIP_BOOTINFO_REQ:
+		ssip_rx_bootinforeq(cl, cmd);
+		break;
+	case SSIP_BOOTINFO_RESP:
+		ssip_rx_bootinforesp(cl, cmd);
+		break;
+	case SSIP_WAKETEST_RESULT:
+		ssip_rx_waketest(cl, cmd);
+		break;
+	case SSIP_START_TRANS:
+		ssip_rx_strans(cl, cmd);
+		break;
+	case SSIP_READY:
+		ssip_rx_ready(cl);
+		break;
+	default:
+		dev_warn(&cl->device, "command 0x%08x not supported\n", cmd);
+		break;
+	}
+}
+
+static void ssip_swbreak_complete(struct hsi_msg *msg)
+{
+	struct hsi_client *cl = msg->cl;
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+
+	ssip_release_cmd(msg);
+	spin_lock_bh(&ssi->lock);
+	if (list_empty(&ssi->txqueue)) {
+		if (atomic_read(&ssi->tx_usecnt)) {
+			ssip_set_txstate(ssi, SEND_READY);
+		} else {
+			ssip_set_txstate(ssi, SEND_IDLE);
+			hsi_stop_tx(cl);
+		}
+		spin_unlock_bh(&ssi->lock);
+	} else {
+		spin_unlock_bh(&ssi->lock);
+		ssip_xmit(cl);
+	}
+	netif_wake_queue(ssi->netdev);
+}
+
+static void ssip_tx_data_complete(struct hsi_msg *msg)
+{
+	struct hsi_client *cl = msg->cl;
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+	struct hsi_msg *cmsg;
+
+	if (msg->status == HSI_STATUS_ERROR) {
+		dev_err(&cl->device, "TX data error\n");
+		ssip_error(cl);
+		goto out;
+	}
+	spin_lock_bh(&ssi->lock);
+	if (list_empty(&ssi->txqueue)) {
+		ssip_set_txstate(ssi, SENDING_SWBREAK);
+		spin_unlock_bh(&ssi->lock);
+		cmsg = ssip_claim_cmd(ssi);
+		ssip_set_cmd(cmsg, SSIP_SWBREAK_CMD);
+		cmsg->complete = ssip_swbreak_complete;
+		dev_dbg(&cl->device, "Send SWBREAK\n");
+		hsi_async_write(cl, cmsg);
+	} else {
+		spin_unlock_bh(&ssi->lock);
+		ssip_xmit(cl);
+	}
+out:
+	ssip_free_data(msg);
+}
+
+static void ssip_port_event(struct hsi_client *cl, unsigned long event)
+{
+	switch (event) {
+	case HSI_EVENT_START_RX:
+		ssip_start_rx(cl);
+		break;
+	case HSI_EVENT_STOP_RX:
+		ssip_stop_rx(cl);
+		break;
+	default:
+		return;
+	}
+}
+
+static int ssip_pn_open(struct net_device *dev)
+{
+	struct hsi_client *cl = to_hsi_client(dev->dev.parent);
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+	int err;
+
+	err = hsi_claim_port(cl, 1);
+	if (err < 0) {
+		dev_err(&cl->device, "SSI port already claimed\n");
+		return err;
+	}
+	err = hsi_register_port_event(cl, ssip_port_event);
+	if (err < 0) {
+		dev_err(&cl->device, "Register HSI port event failed (%d)\n",
+			err);
+		hsi_release_port(cl);
+		return err;
+	}
+	dev_dbg(&cl->device, "Configuring SSI port\n");
+	hsi_setup(cl);
+
+	if (!test_and_set_bit(SSIP_WAKETEST_FLAG, &ssi->flags))
+		ssi_waketest(cl, 1); /* FIXME: To be removed */
+
+	spin_lock_bh(&ssi->lock);
+	ssi->main_state = HANDSHAKE;
+	spin_unlock_bh(&ssi->lock);
+
+	ssip_send_bootinfo_req_cmd(cl);
+
+	return 0;
+}
+
+static int ssip_pn_stop(struct net_device *dev)
+{
+	struct hsi_client *cl = to_hsi_client(dev->dev.parent);
+
+	ssip_reset(cl);
+	hsi_unregister_port_event(cl);
+	hsi_release_port(cl);
+
+	return 0;
+}
+
+static void ssip_xmit_work(struct work_struct *work)
+{
+	struct ssi_protocol *ssi =
+				container_of(work, struct ssi_protocol, work);
+	struct hsi_client *cl = ssi->cl;
+
+	ssip_xmit(cl);
+}
+
+static int ssip_pn_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	struct hsi_client *cl = to_hsi_client(dev->dev.parent);
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+	struct hsi_msg *msg;
+
+	if ((skb->protocol != htons(ETH_P_PHONET)) ||
+					(skb->len < SSIP_MIN_PN_HDR))
+		goto drop;
+	/* Pad to 32-bits - FIXME: Revisit*/
+	if ((skb->len & 3) && skb_pad(skb, 4 - (skb->len & 3)))
+		goto inc_dropped;
+
+	/*
+	 * Modem sends Phonet messages over SSI with its own endianness.
+	 * Assume that modem has the same endianness as we do.
+	 */
+	if (skb_cow_head(skb, 0))
+		goto drop;
+
+	/* length field is exchanged in network byte order */
+	((u16 *)skb->data)[2] = htons(((u16 *)skb->data)[2]);
+
+	msg = ssip_alloc_data(ssi, skb, GFP_ATOMIC);
+	if (!msg) {
+		dev_dbg(&cl->device, "Dropping tx data: No memory\n");
+		goto drop;
+	}
+	msg->complete = ssip_tx_data_complete;
+
+	spin_lock_bh(&ssi->lock);
+	if (unlikely(ssi->main_state != ACTIVE)) {
+		spin_unlock_bh(&ssi->lock);
+		dev_dbg(&cl->device, "Dropping tx data: CMT is OFFLINE\n");
+		goto drop2;
+	}
+	list_add_tail(&msg->link, &ssi->txqueue);
+	ssi->txqueue_len++;
+	if (dev->tx_queue_len < ssi->txqueue_len) {
+		dev_info(&cl->device, "TX queue full %d\n", ssi->txqueue_len);
+		netif_stop_queue(dev);
+	}
+	if (ssi->send_state == SEND_IDLE) {
+		ssip_set_txstate(ssi, WAIT4READY);
+		spin_unlock_bh(&ssi->lock);
+		dev_dbg(&cl->device, "Start TX qlen %d\n", ssi->txqueue_len);
+		hsi_start_tx(cl);
+	} else if (ssi->send_state == SEND_READY) {
+		/* Needed for cmt-speech workaround */
+		dev_dbg(&cl->device, "Start TX on SEND READY qlen %d\n",
+							ssi->txqueue_len);
+		spin_unlock_bh(&ssi->lock);
+		schedule_work(&ssi->work);
+	} else {
+		spin_unlock_bh(&ssi->lock);
+	}
+	dev->stats.tx_packets++;
+	dev->stats.tx_bytes += skb->len;
+
+	return 0;
+drop2:
+	hsi_free_msg(msg);
+drop:
+	dev_kfree_skb(skb);
+inc_dropped:
+	dev->stats.tx_dropped++;
+
+	return 0;
+}
+
+/* CMT reset event handler */
+void ssip_reset_event(struct hsi_client *master)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(master);
+	dev_err(&ssi->cl->device, "CMT reset detected!\n");
+	ssip_error(ssi->cl);
+}
+EXPORT_SYMBOL_GPL(ssip_reset_event);
+
+static const struct net_device_ops ssip_pn_ops = {
+	.ndo_open	= ssip_pn_open,
+	.ndo_stop	= ssip_pn_stop,
+	.ndo_start_xmit	= ssip_pn_xmit,
+};
+
+static void ssip_pn_setup(struct net_device *dev)
+{
+	static const u8 addr = PN_MEDIA_SOS;
+
+	dev->features		= 0;
+	dev->netdev_ops		= &ssip_pn_ops;
+	dev->type		= ARPHRD_PHONET;
+	dev->flags		= IFF_POINTOPOINT | IFF_NOARP;
+	dev->mtu		= SSIP_DEFAULT_MTU;
+	dev->hard_header_len	= 1;
+	dev->addr_len		= 1;
+	dev_addr_set(dev, &addr);
+	dev->tx_queue_len	= SSIP_TXQUEUE_LEN;
+
+	dev->needs_free_netdev	= true;
+	dev->header_ops		= &phonet_header_ops;
+}
+
+static int ssi_protocol_probe(struct device *dev)
+{
+	static const char ifname[] = "phonet%d";
+	struct hsi_client *cl = to_hsi_client(dev);
+	struct ssi_protocol *ssi;
+	int err;
+
+	ssi = kzalloc(sizeof(*ssi), GFP_KERNEL);
+	if (!ssi)
+		return -ENOMEM;
+
+	spin_lock_init(&ssi->lock);
+	timer_setup(&ssi->rx_wd, ssip_rx_wd, TIMER_DEFERRABLE);
+	timer_setup(&ssi->tx_wd, ssip_tx_wd, TIMER_DEFERRABLE);
+	timer_setup(&ssi->keep_alive, ssip_keep_alive, 0);
+	INIT_LIST_HEAD(&ssi->txqueue);
+	INIT_LIST_HEAD(&ssi->cmdqueue);
+	atomic_set(&ssi->tx_usecnt, 0);
+	hsi_client_set_drvdata(cl, ssi);
+	ssi->cl = cl;
+	INIT_WORK(&ssi->work, ssip_xmit_work);
+
+	ssi->channel_id_cmd = hsi_get_channel_id_by_name(cl, "mcsaab-control");
+	if (ssi->channel_id_cmd < 0) {
+		err = ssi->channel_id_cmd;
+		dev_err(dev, "Could not get cmd channel (%d)\n", err);
+		goto out;
+	}
+
+	ssi->channel_id_data = hsi_get_channel_id_by_name(cl, "mcsaab-data");
+	if (ssi->channel_id_data < 0) {
+		err = ssi->channel_id_data;
+		dev_err(dev, "Could not get data channel (%d)\n", err);
+		goto out;
+	}
+
+	err = ssip_alloc_cmds(ssi);
+	if (err < 0) {
+		dev_err(dev, "No memory for commands\n");
+		goto out;
+	}
+
+	ssi->netdev = alloc_netdev(0, ifname, NET_NAME_UNKNOWN, ssip_pn_setup);
+	if (!ssi->netdev) {
+		dev_err(dev, "No memory for netdev\n");
+		err = -ENOMEM;
+		goto out1;
+	}
+
+	/* MTU range: 6 - 65535 */
+	ssi->netdev->min_mtu = PHONET_MIN_MTU;
+	ssi->netdev->max_mtu = SSIP_MAX_MTU;
+
+	SET_NETDEV_DEV(ssi->netdev, dev);
+	netif_carrier_off(ssi->netdev);
+	err = register_netdev(ssi->netdev);
+	if (err < 0) {
+		dev_err(dev, "Register netdev failed (%d)\n", err);
+		goto out2;
+	}
+
+	list_add(&ssi->link, &ssip_list);
+
+	dev_dbg(dev, "channel configuration: cmd=%d, data=%d\n",
+		ssi->channel_id_cmd, ssi->channel_id_data);
+
+	return 0;
+out2:
+	free_netdev(ssi->netdev);
+out1:
+	ssip_free_cmds(ssi);
+out:
+	kfree(ssi);
+
+	return err;
+}
+
+static int ssi_protocol_remove(struct device *dev)
+{
+	struct hsi_client *cl = to_hsi_client(dev);
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+
+	list_del(&ssi->link);
+	unregister_netdev(ssi->netdev);
+	ssip_free_cmds(ssi);
+	hsi_client_set_drvdata(cl, NULL);
+	kfree(ssi);
+
+	return 0;
+}
+
+static struct hsi_client_driver ssip_driver = {
+	.driver = {
+		.name	= "ssi-protocol",
+		.owner	= THIS_MODULE,
+		.probe	= ssi_protocol_probe,
+		.remove	= ssi_protocol_remove,
+	},
+};
+
+static int __init ssip_init(void)
+{
+	pr_info("SSI protocol aka McSAAB added\n");
+
+	return hsi_register_client_driver(&ssip_driver);
+}
+module_init(ssip_init);
+
+static void __exit ssip_exit(void)
+{
+	hsi_unregister_client_driver(&ssip_driver);
+	pr_info("SSI protocol driver removed\n");
+}
+module_exit(ssip_exit);
+
+MODULE_ALIAS("hsi:ssi-protocol");
+MODULE_AUTHOR("Carlos Chinea <carlos.chinea@nokia.com>");
+MODULE_AUTHOR("Remi Denis-Courmont <remi.denis-courmont@nokia.com>");
+MODULE_DESCRIPTION("SSI protocol improved aka McSAAB");
+MODULE_LICENSE("GPL");