modem: Add M6718 IPC SPI driver state machine

Adds the implementation of the driver protocol state machine.

ST-Ericsson ID: 369397
ST-Ericsson FOSS-OUT ID: STETL-FOSS-OUT-12224
ST-Ericsson Linux next: NA

Change-Id: Iffa99154ab2d3f0150c96c7bc535ffe26f6988db
Signed-off-by: Chris Blair <chris.blair@stericsson.com>
Reviewed-on: http://gerrit.lud.stericsson.com/gerrit/36501
Reviewed-by: QATOOLS
Reviewed-by: QABUILD
Reviewed-by: Jonas ABERG <jonas.aberg@stericsson.com>

4 files changed, 1424 insertions, 10 deletions

diff --git a/drivers/modem/m6718_spi/Makefile b/drivers/modem/m6718_spi/Makefile
index 5cb265b00ac..a0a82c30b07 100644
--- a/drivers/modem/m6718_spi/Makefile
+++ b/drivers/modem/m6718_spi/Makefile
@@ -6,7 +6,7 @@ EXTRA_CFLAGS += -DDEBUG
 endif
 
 m6718_modem_spi-objs := modem_driver.o protocol.o util.o queue.o debug.o \
-			netlink.o
+			netlink.o statemachine.o
 
 ifeq ($(CONFIG_MODEM_M6718_SPI_ENABLE_FEATURE_MODEM_STATE),y)
 m6718_modem_spi-objs += modem_state.o
diff --git a/drivers/modem/m6718_spi/modem_statemachine.h b/drivers/modem/m6718_spi/modem_statemachine.h
index bc737dbb7e8..55e4a520d3d 100644
--- a/drivers/modem/m6718_spi/modem_statemachine.h
+++ b/drivers/modem/m6718_spi/modem_statemachine.h
@@ -71,4 +71,11 @@ struct ipc_sm_state {
 	u8 events;
 };
 
+const struct ipc_sm_state *ipc_sm_idle_state(struct ipc_link_context *context);
+const struct ipc_sm_state *ipc_sm_init_state(struct ipc_link_context *context);
+const struct ipc_sm_state *ipc_sm_state(u8 id);
+bool ipc_sm_valid_for_state(u8 event, const struct ipc_sm_state *state);
+
+void ipc_sm_kick(u8 event, struct ipc_link_context *context);
+
 #endif /* _MODEM_STATEMACHINE_H_ */
diff --git a/drivers/modem/m6718_spi/protocol.c b/drivers/modem/m6718_spi/protocol.c
index 86b124120ce..aa21d4dbcde 100644
--- a/drivers/modem/m6718_spi/protocol.c
+++ b/drivers/modem/m6718_spi/protocol.c
@@ -79,12 +79,12 @@ bool modem_protocol_channel_is_open(u8 channel)
 
 void modem_comms_timeout(unsigned long data)
 {
-	/* TODO: statemachine will be kicked here */
+	ipc_sm_kick(IPC_SM_RUN_COMMS_TMO, (struct ipc_link_context *)data);
 }
 
 void slave_stable_timeout(unsigned long data)
 {
-	/* TODO: statemachine will be kicked here */
+	ipc_sm_kick(IPC_SM_RUN_STABLE_TMO, (struct ipc_link_context *)data);
 }
 
 /**
@@ -150,7 +150,7 @@ int modem_m6718_spi_send(struct modem_spi_dev *modem_spi_dev, u8 channel,
 	if (ipc_util_link_is_idle(context)) {
 		dev_dbg(modem_spi_dev->dev,
 			"link %d is idle, kicking\n", channels[channel].link);
-		/* TODO: statemachine will be kicked here */
+		ipc_sm_kick(IPC_SM_RUN_TX_REQ, context);
 	} else {
 		dev_dbg(modem_spi_dev->dev,
 			"link %d is already running\n", channels[channel].link);
@@ -198,7 +198,8 @@ bool modem_protocol_is_busy(struct spi_device *sdev)
 
 static void spi_tfr_complete(void *context)
 {
-	/* TODO: statemachine will be kicked here */
+	ipc_sm_kick(IPC_SM_RUN_TFR_COMPLETE,
+		(struct ipc_link_context *)context);
 }
 
 static irqreturn_t slave_ready_irq(int irq, void *dev)
@@ -221,7 +222,7 @@ static irqreturn_t slave_ready_irq(int irq, void *dev)
 		return IRQ_HANDLED;
 	}
 #endif
-	/* TODO: statemachine will be kicked here */
+	ipc_sm_kick(IPC_SM_RUN_SLAVE_IRQ, context);
 	return IRQ_HANDLED;
 }
 
@@ -243,12 +244,14 @@ static int modem_state_callback(unsigned long unused)
 		 */
 		for (i = 0; i < IPC_NBR_SUPPORTED_SPI_LINKS; i++)
 			ipc_util_link_gpio_config(&contexts[i]);
-		/* TODO: statemachine will be kicked here */
+		ipc_sm_kick(IPC_SM_RUN_INIT, &contexts[0]);
 		break;
 	case MODEM_STATE_OFF:
 	case MODEM_STATE_RESET:
 	case MODEM_STATE_CRASH:
-		/* TODO: statemachine will be kicked here */
+		/* force all links to reset */
+		for (i = 0; i < IPC_NBR_SUPPORTED_SPI_LINKS; i++)
+			ipc_sm_kick(IPC_SM_RUN_RESET, &contexts[i]);
 		break;
 	default:
 		break;
@@ -307,6 +310,7 @@ int modem_protocol_probe(struct spi_device *sdev)
 	atomic_set(&context->state_int,
 		ipc_util_int_level_inactive(context));
 	spin_lock_init(&context->sm_lock);
+	context->state = ipc_sm_init_state(context);
 	ipc_util_spi_message_init(context, spi_tfr_complete);
 	init_timer(&context->comms_timer);
 	context->comms_timer.function = modem_comms_timeout;
@@ -333,7 +337,8 @@ int modem_protocol_probe(struct spi_device *sdev)
 	 * For link0 (the handshake link) we force a state transition now so
 	 * that it prepares for boot sync.
 	 */
-	/* TODO: statemachine will be kicked here */
+	if (link->id == 0)
+		ipc_sm_kick(IPC_SM_RUN_INIT, context);
 
 	/*
 	 * unlikely but possible: for links other than 0, check if handshake is
@@ -345,7 +350,7 @@ int modem_protocol_probe(struct spi_device *sdev)
 		dev_dbg(&sdev->dev,
 			"link %d: boot sync is done, kicking state machine\n",
 			link->id);
-		/* TODO: statemachine will be kicked here */
+		ipc_sm_kick(IPC_SM_RUN_INIT, context);
 	}
 	return 0;
 }
diff --git a/drivers/modem/m6718_spi/statemachine.c b/drivers/modem/m6718_spi/statemachine.c
new file mode 100644
index 00000000000..a2092cd2f94
--- /dev/null
+++ b/drivers/modem/m6718_spi/statemachine.c
@@ -0,0 +1,1402 @@
+/*
+ * Copyright (C) ST-Ericsson SA 2010,2011
+ *
+ * Author: Chris Blair <chris.blair@stericsson.com> for ST-Ericsson
+ *
+ * License terms: GNU General Public License (GPL) version 2
+ *
+ * U9500 <-> M6718 IPC protocol implementation using SPI.
+ *   state machine definition and functionality.
+ */
+#include <linux/modem/m6718_spi/modem_driver.h>
+#include "modem_statemachine.h"
+#include "modem_util.h"
+#include "modem_netlink.h"
+#include "modem_debug.h"
+#include "modem_queue.h"
+#include "modem_protocol.h"
+
+#ifdef CONFIG_MODEM_M6718_SPI_ENABLE_FEATURE_MODEM_STATE
+#include "modem_state.h"
+#endif
+
+#define CMD_BOOTREQ  (1)
+#define CMD_BOOTRESP (2)
+#define CMD_WRITE    (3)
+#define CMD_READ     (4)
+
+static u8 sm_init_enter(u8 event, struct ipc_link_context *context)
+{
+#ifdef CONFIG_MODEM_M6718_SPI_ENABLE_FEATURE_MODEM_STATE
+	/* if modem is off un-configure the IPC GPIO pins for low-power */
+	if (modem_state_get_state() == MODEM_STATE_OFF) {
+		dev_info(&context->sdev->dev,
+			"link %d: modem is off, un-configuring GPIO\n",
+			context->link->id);
+		ipc_util_link_gpio_unconfig(context);
+	}
+#endif
+	/* nothing more to do until an event happens */
+	return IPC_SM_RUN_NONE;
+}
+
+static const struct ipc_sm_state *sm_init_exit(u8 event,
+	struct ipc_link_context *context)
+{
+	bool int_active = false;
+
+	/*
+	 * For reset event just re-enter init in case the modem has
+	 * powered off - we need to reconfigure our GPIO pins
+	 */
+	if (event == IPC_SM_RUN_RESET)
+		return ipc_sm_state(IPC_SM_INIT);
+
+	/* re-sample link INT pin */
+	int_active = ipc_util_int_is_active(context);
+	atomic_set(&context->state_int, int_active);
+
+	dev_info(&context->sdev->dev,
+		"link %d: link initialised; SS:INACTIVE(%d) INT:%s(%d)\n",
+		context->link->id,
+		ipc_util_ss_level_inactive(context),
+		int_active ? "ACTIVE" : "INACTIVE",
+		int_active ? ipc_util_int_level_active(context) :
+				ipc_util_int_level_inactive(context));
+
+	/* handshake is only on link 0 */
+	if (context->link->id == 0) {
+		if (!int_active) {
+			dev_info(&context->sdev->dev,
+				"link %d: slave INT signal is inactive\n",
+				context->link->id);
+			/* start boot handshake */
+			return ipc_sm_state(IPC_SM_SLW_TX_BOOTREQ);
+		} else {
+			/* wait for slave INT signal to stabilise inactive */
+			return ipc_sm_state(IPC_SM_WAIT_SLAVE_STABLE);
+		}
+	} else {
+		dev_info(&context->sdev->dev,
+			"link %d: boot sync not needed, going idle\n",
+			context->link->id);
+		return ipc_sm_state(IPC_SM_IDL);
+	}
+}
+
+static const struct ipc_sm_state *sm_init_aud_exit(u8 event,
+	struct ipc_link_context *context)
+{
+	bool int_active = false;
+
+	/*
+	 * For reset event just re-enter init in case the modem has
+	 * powered off - we need to reconfigure our GPIO pins
+	 */
+	if (event == IPC_SM_RUN_RESET)
+		return ipc_sm_state(IPC_SM_INIT_AUD);
+
+	/* re-sample link INT pin */
+	int_active = ipc_util_int_is_active(context);
+	atomic_set(&context->state_int, int_active);
+
+	dev_info(&context->sdev->dev,
+		"link %d: link initialised; SS:INACTIVE(%d) INT:%s(%d)\n",
+		context->link->id,
+		ipc_util_ss_level_inactive(context),
+		int_active ? "ACTIVE" : "INACTIVE",
+		int_active ? ipc_util_int_level_active(context) :
+				ipc_util_int_level_inactive(context));
+	dev_info(&context->sdev->dev,
+		"link %d: boot sync not needed, going idle\n",
+		context->link->id);
+	return ipc_sm_state(IPC_SM_IDL_AUD);
+}
+
+static u8 sm_wait_slave_stable_enter(u8 event, struct ipc_link_context *context)
+{
+	static unsigned long printk_warn_time;
+	if (printk_timed_ratelimit(&printk_warn_time, 60 * 1000))
+		dev_info(&context->sdev->dev,
+			"link %d: waiting for stable inactive slave INT\n",
+			context->link->id);
+	ipc_util_start_slave_stable_timer(context);
+	return IPC_SM_RUN_NONE;
+}
+
+static const struct ipc_sm_state *sm_wait_slave_stable_exit(u8 event,
+	struct ipc_link_context *context)
+{
+	if (!ipc_util_int_is_active(context)) {
+		dev_info(&context->sdev->dev,
+			"link %d: slave INT signal is stable inactive\n",
+			context->link->id);
+		return ipc_sm_state(IPC_SM_SLW_TX_BOOTREQ);
+	} else {
+		return ipc_sm_state(IPC_SM_WAIT_SLAVE_STABLE);
+	}
+}
+
+static u8 sm_wait_handshake_inactive_enter(u8 event,
+	struct ipc_link_context *context)
+{
+	dev_info(&context->sdev->dev,
+		"link %d: waiting for stable inactive slave INT\n",
+		context->link->id);
+	ipc_util_start_slave_stable_timer(context);
+	return IPC_SM_RUN_NONE;
+}
+
+static const struct ipc_sm_state *sm_wait_handshake_inactive_exit(u8 event,
+	struct ipc_link_context *context)
+{
+	int i;
+
+	if (!ipc_util_int_is_active(context)) {
+		dev_info(&context->sdev->dev,
+			"link %d: slave INT signal is inactive, going idle\n",
+			context->link->id);
+
+		/* modem sync is done */
+		atomic_inc(&l1_context.boot_sync_done);
+		ipc_broadcast_modem_online(context);
+
+		/*
+		 * Kick the state machine for any initialised links - skip link0
+		 * since this link has just completed handshake
+		 */
+		for (i = 1; i < IPC_NBR_SUPPORTED_SPI_LINKS; i++)
+			if (l1_context.device_context[i].state != NULL) {
+				dev_dbg(&context->sdev->dev,
+					"link %d has already been probed, "
+					"kicking state machine\n", i);
+				ipc_sm_kick(IPC_SM_RUN_INIT,
+					&l1_context.device_context[i]);
+			}
+		return ipc_sm_state(IPC_SM_IDL);
+	} else {
+		return ipc_sm_state(IPC_SM_WAIT_HANDSHAKE_INACTIVE);
+	}
+}
+
+static u8 sm_idl_enter(u8 event, struct ipc_link_context *context)
+{
+	ipc_util_deactivate_ss(context);
+	ipc_dbg_enter_idle(context);
+
+	/* check if tx queue contains items */
+	if (atomic_read(&context->tx_q_count) > 0) {
+		dev_dbg(&context->sdev->dev,
+			"link %d: tx queue contains items\n",
+			context->link->id);
+		return IPC_SM_RUN_TX_REQ;
+	}
+
+	/* check if modem has already requested transaction start */
+	if (atomic_read(&context->state_int)) {
+		dev_dbg(&context->sdev->dev,
+			"link %d: slave has already signalled ready\n",
+			context->link->id);
+		return IPC_SM_RUN_SLAVE_IRQ;
+	}
+
+	dev_dbg(&context->sdev->dev,
+		"link %d: going idle\n", context->link->id);
+	return IPC_SM_RUN_NONE;
+}
+
+static const struct ipc_sm_state *sm_idl_exit(u8 event,
+	struct ipc_link_context *context)
+{
+	ipc_dbg_exit_idle(context);
+	if (event == IPC_SM_RUN_RESET)
+		return ipc_sm_state(IPC_SM_RESET);
+	else if (event == IPC_SM_RUN_TX_REQ)
+		return ipc_sm_state(IPC_SM_SLW_TX_WR_CMD);
+	else if (event == IPC_SM_RUN_SLAVE_IRQ)
+		return ipc_sm_state(IPC_SM_SLW_TX_RD_CMD);
+	else
+		return ipc_sm_state(IPC_SM_HALT);
+}
+
+static const struct ipc_sm_state *sm_idl_aud_exit(u8 event,
+	struct ipc_link_context *context)
+{
+	ipc_dbg_exit_idle(context);
+	if (event == IPC_SM_RUN_RESET)
+		return ipc_sm_state(IPC_SM_RESET_AUD);
+
+	/* always transmit data first */
+	return ipc_sm_state(IPC_SM_SLW_TX_WR_DAT_AUD);
+}
+
+static u8 sm_slw_tx_wr_cmd_enter(u8 event, struct ipc_link_context *context)
+{
+	struct ipc_tx_queue *frame;
+
+	/* get the frame from the head of the tx queue */
+	if (ipc_queue_is_empty(context)) {
+		dev_err(&context->sdev->dev,
+			"link %d error: tx queue is empty!\n",
+			context->link->id);
+		return IPC_SM_RUN_ABORT;
+	}
+	frame = ipc_queue_get_frame(context);
+	ipc_dbg_dump_frame(&context->sdev->dev, context->link->id, frame, true);
+
+	context->cmd = ipc_util_make_l1_header(CMD_WRITE, frame->counter,
+		frame->len);
+
+	dev_dbg(&context->sdev->dev,
+		"link %d: TX FRAME cmd %08x (type %d counter %d len %d)\n",
+		context->link->id,
+		context->cmd,
+		ipc_util_get_l1_cmd(context->cmd),
+		ipc_util_get_l1_counter(context->cmd),
+		ipc_util_get_l1_length(context->cmd));
+
+	ipc_util_spi_message_prepare(context, &context->cmd,
+		NULL, IPC_L1_HDR_SIZE);
+	context->frame = frame;
+
+	/* slave might already have signalled ready to transmit */
+	if (atomic_read(&context->state_int)) {
+		dev_dbg(&context->sdev->dev,
+			"link %d: slave has already signalled ready\n",
+			context->link->id);
+		ipc_util_activate_ss(context);
+		return IPC_SM_RUN_SLAVE_IRQ;
+	} else {
+		ipc_util_activate_ss_with_tmo(context);
+		return IPC_SM_RUN_NONE;
+	}
+}
+
+static const struct ipc_sm_state *sm_slw_tx_wr_cmd_exit(u8 event,
+	struct ipc_link_context *context)
+{
+	if (event == IPC_SM_RUN_RESET)
+		return ipc_sm_state(IPC_SM_RESET);
+	else if (event == IPC_SM_RUN_COMMS_TMO)
+		return ipc_sm_state(IPC_SM_HALT);
+	else
+		return ipc_sm_state(IPC_SM_ACT_TX_WR_CMD);
+}
+
+static u8 sm_act_tx_wr_cmd_enter(u8 event, struct ipc_link_context *context)
+{
+	int err;
+
+	/* slave is ready - start the spi transfer */
+	dev_dbg(&context->sdev->dev,
+		"link %d: starting spi tfr\n", context->link->id);
+	err = spi_async(context->sdev, &context->spi_message);
+	if (err < 0) {
+		dev_err(&context->sdev->dev,
+			"link %d error: spi tfr start failed, error %d\n",
+			context->link->id, err);
+		return IPC_SM_RUN_ABORT;
+	}
+	return IPC_SM_RUN_NONE;
+}
+
+static const struct ipc_sm_state *sm_act_tx_wr_cmd_exit(u8 event,
+	struct ipc_link_context *context)
+{
+	if (event == IPC_SM_RUN_RESET)
+		return ipc_sm_state(IPC_SM_RESET);
+	else
+		return ipc_sm_state(IPC_SM_SLW_TX_WR_DAT);
+}
+
+static u8 sm_slw_tx_wr_dat_enter(u8 event, struct ipc_link_context *context)
+{
+	/* prepare to transfer the frame tx data */
+	ipc_util_spi_message_prepare(context, context->frame->data,
+		NULL, context->frame->len);
+
+	/* slave might already have signalled ready to transmit */
+	if (atomic_read(&context->state_int)) {
+		dev_dbg(&context->sdev->dev,
+			"link %d: slave has already signalled ready\n",
+			context->link->id);
+		ipc_util_activate_ss(context);
+		return IPC_SM_RUN_SLAVE_IRQ;
+	} else {
+		ipc_util_activate_ss_with_tmo(context);
+		return IPC_SM_RUN_NONE;
+	}
+}
+
+static u8 sm_slw_tx_wr_dat_aud_enter(u8 event, struct ipc_link_context *context)
+{
+	struct ipc_tx_queue *frame = NULL;
+
+	/* check if there is a frame to be sent */
+	if (!ipc_queue_is_empty(context)) {
+		frame = ipc_queue_get_frame(context);
+	} else {
+		/* no frame to send, create an empty one */
+		dev_dbg(&context->sdev->dev,
+			"link %d: no frame to send, allocating dummy\n",
+			context->link->id);
+		frame = ipc_queue_new_frame(context, 0);
+		if (frame == NULL)
+			return IPC_SM_RUN_ABORT;
+	}
+
+	ipc_dbg_dump_frame(&context->sdev->dev, context->link->id, frame, true);
+
+	/* prepare to transfer the frame tx data */
+	context->frame = frame;
+	ipc_util_spi_message_prepare(context, context->frame->data,
+		NULL, context->frame->len);
+
+	/* slave might already have signalled ready to transmit */
+	if (event == IPC_SM_RUN_SLAVE_IRQ || atomic_read(&context->state_int)) {
+		dev_dbg(&context->sdev->dev,
+			"link %d: slave has already signalled ready\n",
+			context->link->id);
+		ipc_util_activate_ss(context);
+		return IPC_SM_RUN_SLAVE_IRQ;
+	} else {
+		ipc_util_activate_ss_with_tmo(context);
+		return IPC_SM_RUN_NONE;
+	}
+}
+
+static const struct ipc_sm_state *sm_slw_tx_wr_dat_exit(u8 event,
+	struct ipc_link_context *context)
+{
+	if (event == IPC_SM_RUN_RESET)
+		return ipc_sm_state(IPC_SM_RESET);
+	else if (event == IPC_SM_RUN_COMMS_TMO)
+		return ipc_sm_state(IPC_SM_HALT);
+	else
+		return ipc_sm_state(IPC_SM_ACT_TX_WR_DAT);
+}
+
+static const struct ipc_sm_state *sm_slw_tx_wr_dat_aud_exit(u8 event,
+	struct ipc_link_context *context)
+{
+	if (event == IPC_SM_RUN_RESET)
+		return ipc_sm_state(IPC_SM_RESET_AUD);
+	else if (event == IPC_SM_RUN_COMMS_TMO)
+		return ipc_sm_state(IPC_SM_HALT_AUD);
+	else
+		return ipc_sm_state(IPC_SM_ACT_TX_WR_DAT_AUD);
+}
+
+static u8 sm_act_tx_wr_dat_enter(u8 event, struct ipc_link_context *context)
+{
+	int err;
+
+	/* slave is ready - start the spi transfer */
+	dev_dbg(&context->sdev->dev,
+		"link %d: starting spi tfr\n", context->link->id);
+	err = spi_async(context->sdev, &context->spi_message);
+	if (err < 0) {
+		dev_err(&context->sdev->dev,
+			"link %d error: spi tfr start failed, error %d\n",
+			context->link->id, err);
+		return IPC_SM_RUN_ABORT;
+	}
+	return IPC_SM_RUN_NONE;
+}
+
+static const struct ipc_sm_state *sm_act_tx_wr_dat_exit(u8 event,
+	struct ipc_link_context *context)
+{
+	if (event == IPC_SM_RUN_RESET)
+		return ipc_sm_state(IPC_SM_RESET);
+
+#ifdef CONFIG_MODEM_M6718_SPI_ENABLE_FEATURE_THROUGHPUT_MEASUREMENT
+	/* frame is sent, increment link tx counter */
+	context->tx_bytes += context->frame->actual_len;
+#endif
+#ifdef CONFIG_MODEM_M6718_SPI_ENABLE_FEATURE_VERIFY_FRAMES
+	{
+		u8 channel;
+
+		channel = ipc_util_get_l2_channel(*(u32 *)context->frame->data);
+		if (ipc_util_channel_is_loopback(channel)) {
+			context->last_frame = context->frame;
+		} else {
+			ipc_queue_delete_frame(context->frame);
+			context->frame = NULL;
+		}
+	}
+#else
+	/* free the sent frame */
+	ipc_queue_delete_frame(context->frame);
+	context->frame = NULL;
+#endif
+	return ipc_sm_state(IPC_SM_SLW_TX_RD_CMD);
+}
+
+static const struct ipc_sm_state *sm_act_tx_wr_dat_aud_exit(u8 event,
+	struct ipc_link_context *context)
+{
+	if (event == IPC_SM_RUN_RESET)
+		return ipc_sm_state(IPC_SM_RESET_AUD);
+
+#ifdef CONFIG_MODEM_M6718_SPI_ENABLE_FEATURE_THROUGHPUT_MEASUREMENT
+	/* frame is sent, increment link tx counter */
+	context->tx_bytes += context->frame->actual_len;
+#endif
+#ifdef CONFIG_MODEM_M6718_SPI_ENABLE_FEATURE_VERIFY_FRAMES
+	{
+		u8 channel;
+
+		channel = ipc_util_get_l2_channel(*(u32 *)context->frame->data);
+		if (ipc_util_channel_is_loopback(channel)) {
+			/* create a copy of the frame */
+			context->last_frame = ipc_queue_new_frame(context,
+						context->frame->actual_len);
+			memcpy(context->last_frame->data,
+				context->frame->data,
+				context->frame->actual_len);
+		}
+	}
+#endif
+	return ipc_sm_state(IPC_SM_SLW_RX_WR_DAT_AUD);
+}
+
+static u8 sm_slw_tx_rd_cmd_enter(u8 event, struct ipc_link_context *context)
+{
+	context->cmd = ipc_util_make_l1_header(CMD_READ, 0, 0);
+	dev_dbg(&context->sdev->dev,
+		"link %d: cmd %08x (type %d)\n",
+		context->link->id,
+		context->cmd,
+		ipc_util_get_l1_cmd(context->cmd));
+
+	/* prepare the spi message to transfer */
+	ipc_util_spi_message_prepare(context, &context->cmd,
+		NULL, IPC_L1_HDR_SIZE);
+
+	/* check if the slave requested this transaction */
+	if (event == IPC_SM_RUN_SLAVE_IRQ) {
+		dev_dbg(&context->sdev->dev,
+			"link %d: slave initiated transaction, continue\n",
+			context->link->id);
+		ipc_util_activate_ss(context);
+		return IPC_SM_RUN_SLAVE_IRQ;
+	} else {
+		/* slave might already have signalled ready to transmit */
+		if (atomic_read(&context->state_int)) {
+			dev_dbg(&context->sdev->dev,
+				"link %d: slave has already signalled ready\n",
+				context->link->id);
+			ipc_util_activate_ss(context);
+			return IPC_SM_RUN_SLAVE_IRQ;
+		} else {
+			ipc_util_activate_ss_with_tmo(context);
+			return IPC_SM_RUN_NONE;
+		}
+	}
+}
+
+static const struct ipc_sm_state *sm_slw_tx_rd_cmd_exit(u8 event,
+	struct ipc_link_context *context)
+{
+	if (event == IPC_SM_RUN_RESET)
+		return ipc_sm_state(IPC_SM_RESET);
+	else if (event == IPC_SM_RUN_COMMS_TMO)
+		return ipc_sm_state(IPC_SM_HALT);
+	else
+		return ipc_sm_state(IPC_SM_ACT_TX_RD_CMD);
+}
+
+static u8 sm_act_tx_rd_cmd_enter(u8 event, struct ipc_link_context *context)
+{
+	int err;
+
+	/* slave is ready - start the spi transfer */
+	dev_dbg(&context->sdev->dev,
+		"link %d: starting spi tfr\n", context->link->id);
+	err = spi_async(context->sdev, &context->spi_message);
+	if (err < 0) {
+		dev_err(&context->sdev->dev,
+			"link %d error: spi tfr start failed, error %d\n",
+			context->link->id, err);
+		return IPC_SM_RUN_ABORT;
+	}
+	return IPC_SM_RUN_NONE;
+}
+
+static const struct ipc_sm_state *sm_act_tx_rd_cmd_exit(u8 event,
+	struct ipc_link_context *context)
+{
+	if (event == IPC_SM_RUN_RESET)
+		return ipc_sm_state(IPC_SM_RESET);
+	else
+		return ipc_sm_state(IPC_SM_SLW_RX_WR_CMD);
+}
+
+static u8 sm_slw_rx_wr_cmd_enter(u8 event, struct ipc_link_context *context)
+{
+	/* prepare to receive MESSAGE WRITE frame header */
+	ipc_util_spi_message_prepare(context, NULL,
+		&context->cmd, IPC_L1_HDR_SIZE);
+
+	/* slave might already have signalled ready to transmit */
+	if (atomic_read(&context->state_int)) {
+		dev_dbg(&context->sdev->dev,
+			"link %d: slave has already signalled ready\n",
+			context->link->id);
+		ipc_util_activate_ss(context);
+		return IPC_SM_RUN_SLAVE_IRQ;
+	} else {
+		ipc_util_activate_ss_with_tmo(context);
+		return IPC_SM_RUN_NONE;
+	}
+}
+
+static const struct ipc_sm_state *sm_slw_rx_wr_cmd_exit(u8 event,
+	struct ipc_link_context *context)
+{
+	if (event == IPC_SM_RUN_RESET)
+		return ipc_sm_state(IPC_SM_RESET);
+	else if (event == IPC_SM_RUN_COMMS_TMO)
+		return ipc_sm_state(IPC_SM_HALT);
+	else
+		return ipc_sm_state(IPC_SM_ACT_RX_WR_CMD);
+}
+
+static u8 sm_act_rx_wr_cmd_enter(u8 event, struct ipc_link_context *context)
+{
+	int err;
+
+	/* slave is ready - start the spi transfer */
+	dev_dbg(&context->sdev->dev,
+		"link %d: starting spi tfr\n", context->link->id);
+	err = spi_async(context->sdev, &context->spi_message);
+	if (err < 0) {
+		dev_err(&context->sdev->dev,
+			"link %d error: spi tfr start failed, error %d\n",
+			context->link->id, err);
+		return IPC_SM_RUN_ABORT;
+	}
+	return IPC_SM_RUN_NONE;
+}
+
+static const struct ipc_sm_state *sm_act_rx_wr_cmd_exit(u8 event,
+	struct ipc_link_context *context)
+{
+	u8 cmd_type = ipc_util_get_l1_cmd(context->cmd);
+	int counter = ipc_util_get_l1_counter(context->cmd);
+	int length  = ipc_util_get_l1_length(context->cmd);
+
+	dev_dbg(&context->sdev->dev,
+		"link %d: RX HEADER %08x (type %d counter %d length %d)\n",
+		context->link->id,
+		context->cmd,
+		cmd_type,
+		counter,
+		length);
+
+	if (event == IPC_SM_RUN_RESET)
+		return ipc_sm_state(IPC_SM_RESET);
+
+	if (cmd_type == CMD_WRITE) {
+		/* slave has data to send - allocate a frame to hold it */
+		context->frame = ipc_queue_new_frame(context, length);
+		if (context->frame == NULL)
+			return ipc_sm_state(IPC_SM_IDL);
+
+		context->frame->counter = counter;
+		ipc_util_spi_message_prepare(context, NULL,
+			context->frame->data, context->frame->len);
+		return ipc_sm_state(IPC_SM_ACT_RX_WR_DAT);
+	} else {
+		if (cmd_type != 0)
+			dev_err(&context->sdev->dev,
+				"link %d error: received invalid frame type %x "
+				"(%08x)! assuming TRANSACTION_END...\n",
+				context->link->id,
+				cmd_type,
+				context->cmd);
+
+		/* slave has no data to send */
+		dev_dbg(&context->sdev->dev,
+			"link %d: slave has no data to send\n",
+			context->link->id);
+		return ipc_sm_state(IPC_SM_IDL);
+	}
+}
+
+static u8 sm_slw_rx_wr_dat_aud_enter(u8 event, struct ipc_link_context *context)
+{
+	/*
+	 * We're using the same frame buffer we just sent, so no need for a
+	 * new allocation here, just prepare the spi message
+	 */
+	ipc_util_spi_message_prepare(context, NULL,
+		context->frame->data, context->frame->len);
+
+	/* slave might already have signalled ready to transmit */
+	if (atomic_read(&context->state_int)) {
+		dev_dbg(&context->sdev->dev,
+			"link %d: slave has already signalled ready\n",
+			context->link->id);
+		ipc_util_activate_ss(context);
+		return IPC_SM_RUN_SLAVE_IRQ;
+	} else {
+		ipc_util_activate_ss_with_tmo(context);
+		return IPC_SM_RUN_NONE;
+	}
+}
+
+static const struct ipc_sm_state *sm_slw_rx_wr_dat_aud_exit(u8 event,
+	struct ipc_link_context *context)
+{
+	if (event == IPC_SM_RUN_RESET)
+		return ipc_sm_state(IPC_SM_RESET_AUD);
+	else if (event == IPC_SM_RUN_COMMS_TMO)
+		return ipc_sm_state(IPC_SM_HALT_AUD);
+	else
+		return ipc_sm_state(IPC_SM_ACT_RX_WR_DAT_AUD);
+}
+
+static u8 sm_act_rx_wr_dat_enter(u8 event, struct ipc_link_context *context)
+{
+	int err;
+
+	/* assume slave is still ready - prepare and start the spi transfer */
+	ipc_util_spi_message_prepare(context, NULL,
+		context->frame->data, context->frame->len);
+
+	dev_dbg(&context->sdev->dev,
+		"link %d: starting spi tfr\n", context->link->id);
+	err = spi_async(context->sdev, &context->spi_message);
+	if (err < 0) {
+		dev_err(&context->sdev->dev,
+			"link %d error: spi tfr start failed, error %d\n",
+			context->link->id, err);
+		return IPC_SM_RUN_ABORT;
+	}
+	return IPC_SM_RUN_NONE;
+}
+
+static u8 sm_act_rx_wr_dat_aud_enter(u8 event, struct ipc_link_context *context)
+{
+	int err;
+
+	dev_dbg(&context->sdev->dev,
+		"link %d: starting spi tfr\n", context->link->id);
+	err = spi_async(context->sdev, &context->spi_message);
+	if (err < 0) {
+		dev_err(&context->sdev->dev,
+			"link %d error: spi tfr start failed, error %d\n",
+			context->link->id, err);
+		return IPC_SM_RUN_ABORT;
+	}
+	return IPC_SM_RUN_NONE;
+}
+
+static const struct ipc_sm_state *sm_act_rx_wr_dat_exit(u8 event,
+	struct ipc_link_context *context)
+{
+	u32           frame_hdr;
+	unsigned char l2_header;
+	unsigned int  l2_length;
+	u8            *l2_data;
+
+	if (event == IPC_SM_RUN_RESET)
+		return ipc_sm_state(IPC_SM_RESET);
+
+	dev_dbg(&context->sdev->dev,
+		"link %d: RX PAYLOAD %d bytes\n",
+		context->link->id, context->frame->len);
+
+#ifdef CONFIG_MODEM_M6718_SPI_ENABLE_FEATURE_THROUGHPUT_MEASUREMENT
+	/* frame is received, increment link rx counter */
+	context->rx_bytes += context->frame->len;
+#endif
+	/* decode L2 header */
+	frame_hdr = *(u32 *)context->frame->data;
+	l2_header = ipc_util_get_l2_channel(frame_hdr);
+	l2_length = ipc_util_get_l2_length(frame_hdr);
+	l2_data   = (u8 *)context->frame->data + IPC_L2_HDR_SIZE;
+
+	context->frame->actual_len = l2_length + IPC_L2_HDR_SIZE;
+	ipc_dbg_dump_frame(&context->sdev->dev, context->link->id,
+		context->frame, false);
+
+	if (l2_length > (context->frame->len - 4)) {
+		dev_err(&context->sdev->dev,
+			"link %d: suspicious frame: L1 len %d L2 len %d\n",
+			context->link->id, context->frame->len, l2_length);
+	}
+
+	dev_dbg(&context->sdev->dev,
+		"link %d: L2 PDU decode: header 0x%08x channel %d length %d "
+		"data[%02x%02x%02x...]\n",
+		context->link->id, frame_hdr, l2_header, l2_length,
+		l2_data[0], l2_data[1], l2_data[2]);
+
+	if (ipc_util_channel_is_loopback(l2_header))
+		ipc_dbg_verify_rx_frame(context);
+
+	/* pass received frame up to L2mux layer */
+	if (!modem_protocol_channel_is_open(l2_header)) {
+		dev_err(&context->sdev->dev,
+			"link %d error: received frame on invalid channel %d, "
+			"frame discarded\n",
+			context->link->id, l2_header);
+	} else {
+#ifdef CONFIG_MODEM_M6718_SPI_ENABLE_FEATURE_THROUGHPUT_MEASUREMENT
+		/*
+		 * Discard loopback frames if we are taking throughput
+		 * measurements - we'll be loading the links and so will likely
+		 * overload the buffers.
+		 */
+		if (!ipc_util_channel_is_loopback(l2_header))
+#endif
+			modem_m6718_spi_receive(context->sdev,
+				l2_header, l2_length, l2_data);
+	}
+
+	/* data is copied by L2mux so free the frame here */
+	ipc_queue_delete_frame(context->frame);
+	context->frame = NULL;
+
+	/* check tx queue for content */
+	if (!ipc_queue_is_empty(context)) {
+		dev_dbg(&context->sdev->dev,
+			"link %d: tx queue not empty\n", context->link->id);
+		return ipc_sm_state(IPC_SM_SLW_TX_WR_CMD);
+	} else {
+		dev_dbg(&context->sdev->dev,
+			"link %d: tx queue empty\n", context->link->id);
+		return ipc_sm_state(IPC_SM_SLW_TX_RD_CMD);
+	}
+}
+
+static const struct ipc_sm_state *sm_act_rx_wr_dat_aud_exit(u8 event,
+	struct ipc_link_context *context)
+{
+	u32           frame_hdr;
+	unsigned char l2_header;
+	unsigned int  l2_length;
+	u8            *l2_data;
+
+	if (event == IPC_SM_RUN_RESET)
+		return ipc_sm_state(IPC_SM_RESET_AUD);
+
+	dev_dbg(&context->sdev->dev,
+		"link %d: RX PAYLOAD %d bytes\n",
+		context->link->id, context->frame->len);
+
+	/* decode L2 header */
+	frame_hdr = *(u32 *)context->frame->data;
+	l2_header = ipc_util_get_l2_channel(frame_hdr);
+	l2_length = ipc_util_get_l2_length(frame_hdr);
+	l2_data   = (u8 *)context->frame->data + IPC_L2_HDR_SIZE;
+
+#ifdef CONFIG_MODEM_M6718_SPI_ENABLE_FEATURE_THROUGHPUT_MEASUREMENT
+	/* frame is received, increment link rx counter */
+	context->rx_bytes += l2_length;
+#endif
+	if (frame_hdr != 0)
+		context->frame->actual_len = l2_length + IPC_L2_HDR_SIZE;
+	else
+		context->frame->actual_len = 0;
+	ipc_dbg_dump_frame(&context->sdev->dev, context->link->id,
+		context->frame, false);
+
+	if (l2_length > (context->frame->len - 4))
+		dev_err(&context->sdev->dev,
+			"link %d: suspicious frame: L1 len %d L2 len %d\n",
+			context->link->id, context->frame->len, l2_length);
+
+	dev_dbg(&context->sdev->dev,
+		"link %d: L2 PDU decode: header 0x%08x channel %d length %d "
+		"data[%02x%02x%02x...]\n",
+		context->link->id, frame_hdr, l2_header, l2_length,
+		l2_data[0], l2_data[1], l2_data[2]);
+
+	if (ipc_util_channel_is_loopback(l2_header))
+		ipc_dbg_verify_rx_frame(context);
+
+	/* did the slave actually have anything to send? */
+	if (frame_hdr != 0) {
+		/* pass received frame up to L2mux layer */
+		if (!modem_protocol_channel_is_open(l2_header)) {
+			dev_err(&context->sdev->dev,
+				"link %d error: received frame on invalid "
+				"channel %d, frame discarded\n",
+				context->link->id, l2_header);
+		} else {
+#ifdef CONFIG_MODEM_M6718_SPI_ENABLE_FEATURE_THROUGHPUT_MEASUREMENT
+			/*
+			 * Discard loopback frames if we are taking throughput
+			 * measurements - we'll be loading the links and so will
+			 * likely overload the buffers.
+			 */
+			if (!ipc_util_channel_is_loopback(l2_header))
+#endif
+				modem_m6718_spi_receive(context->sdev,
+					l2_header, l2_length, l2_data);
+		}
+	} else {
+		dev_dbg(&context->sdev->dev,
+			"link %d: received dummy frame, discarding\n",
+			context->link->id);
+	}
+
+	/* data is copied by L2mux so free the frame here */
+	ipc_queue_delete_frame(context->frame);
+	context->frame = NULL;
+
+	/* audio link goes idle ready for next transaction */
+	return ipc_sm_state(IPC_SM_IDL_AUD);
+}
+
+static u8 sm_halt_enter(u8 event, struct ipc_link_context *context)
+{
+	dev_err(&context->sdev->dev,
+		"link %d error: HALTED\n", context->link->id);
+
+#ifdef CONFIG_MODEM_M6718_SPI_ENABLE_FEATURE_MODEM_STATE
+	/*
+	 * Force modem reset, this will cause a reset event from the modemstate
+	 * driver which will reset the links. If debugfs is enabled then there
+	 * is a userspace file which controls whether MSR is enabled or not.
+	 */
+#ifdef CONFIG_DEBUG_FS
+	if (l1_context.msr_disable) {
+		dev_info(&context->sdev->dev,
+			"link %d: MSR is disabled by user, "
+			"not requesting modem reset\n", context->link->id);
+		return IPC_SM_RUN_RESET;
+	}
+#endif
+	modem_state_force_reset();
+#endif
+	return IPC_SM_RUN_RESET;
+}
+
+static const struct ipc_sm_state *sm_halt_exit(u8 event,
+	struct ipc_link_context *context)
+{
+	return ipc_sm_state(IPC_SM_RESET);
+}
+
+static const struct ipc_sm_state *sm_halt_aud_exit(u8 event,
+	struct ipc_link_context *context)
+{
+	return ipc_sm_state(IPC_SM_RESET_AUD);
+}
+
+static u8 sm_reset_enter(u8 event, struct ipc_link_context *context)
+{
+	dev_err(&context->sdev->dev,
+		"link %d resetting\n", context->link->id);
+
+	if (context->link->id == 0)
+		ipc_broadcast_modem_reset(context);
+
+	ipc_util_deactivate_ss(context);
+	ipc_queue_reset(context);
+	if (context->frame != NULL) {
+		ipc_queue_delete_frame(context->frame);
+		context->frame = NULL;
+	}
+#ifdef CONFIG_MODEM_M6718_SPI_ENABLE_FEATURE_VERIFY_FRAMES
+	if (context->last_frame != NULL) {
+		ipc_queue_delete_frame(context->last_frame);
+		context->last_frame = NULL;
+	}
+#endif
+	dev_dbg(&context->sdev->dev,
+		"link %d reset completed\n", context->link->id);
+
+	return IPC_SM_RUN_RESET;
+}
+
+static const struct ipc_sm_state *sm_reset_exit(u8 event,
+	struct ipc_link_context *context)
+{
+	return ipc_sm_state(IPC_SM_INIT);
+}
+
+static const struct ipc_sm_state *sm_reset_aud_exit(u8 event,
+	struct ipc_link_context *context)
+{
+	return ipc_sm_state(IPC_SM_INIT_AUD);
+}
+
+static u8 sm_slw_tx_bootreq_enter(u8 event, struct ipc_link_context *context)
+{
+	dev_info(&context->sdev->dev,
+		"link %d: waiting for boot sync\n", context->link->id);
+
+	ipc_util_activate_ss(context);
+	context->cmd = ipc_util_make_l1_header(CMD_BOOTREQ, 0,
+		IPC_DRIVER_VERSION);
+	dev_dbg(&context->sdev->dev,
+		"link %d: TX HEADER cmd %08x (type %x)\n",
+		context->link->id,
+		context->cmd,
+		ipc_util_get_l1_cmd(context->cmd));
+	ipc_util_spi_message_prepare(context, &context->cmd,
+		NULL, IPC_L1_HDR_SIZE);
+
+	/* wait now for the slave to indicate ready... */
+	return IPC_SM_RUN_NONE;
+}
+
+static const struct ipc_sm_state *sm_slw_tx_bootreq_exit(u8 event,
+	struct ipc_link_context *context)
+{
+	return ipc_sm_state(IPC_SM_ACT_TX_BOOTREQ);
+}
+
+static u8 sm_act_tx_bootreq_enter(u8 event, struct ipc_link_context *context)
+{
+	int err;
+
+	/* slave is ready - start the spi transfer */
+	dev_dbg(&context->sdev->dev,
+		"link %d: starting spi tfr\n", context->link->id);
+	err = spi_async(context->sdev, &context->spi_message);
+	if (err < 0) {
+		dev_err(&context->sdev->dev,
+			"link %d error: spi tfr start failed, error %d\n",
+			context->link->id, err);
+		return IPC_SM_RUN_ABORT;
+	}
+	return IPC_SM_RUN_NONE;
+}
+
+static const struct ipc_sm_state *sm_act_tx_bootreq_exit(u8 event,
+	struct ipc_link_context *context)
+{
+	return ipc_sm_state(IPC_SM_SLW_RX_BOOTRESP);
+}
+
+static u8 sm_slw_rx_bootresp_enter(u8 event, struct ipc_link_context *context)
+{
+	/* prepare to receive BOOTRESP frame header */
+	ipc_util_spi_message_prepare(context, NULL,
+		&context->cmd, IPC_L1_HDR_SIZE);
+
+	/* slave might already have signalled ready to transmit */
+	if (atomic_read(&context->state_int)) {
+		dev_dbg(&context->sdev->dev,
+			"link %d: slave has already signalled ready\n",
+			context->link->id);
+		ipc_util_activate_ss(context);
+		return IPC_SM_RUN_SLAVE_IRQ;
+	} else {
+		ipc_util_activate_ss_with_tmo(context);
+		return IPC_SM_RUN_NONE;
+	}
+}
+
+static const struct ipc_sm_state *sm_slw_rx_bootresp_exit(u8 event,
+	struct ipc_link_context *context)
+{
+	if (event == IPC_SM_RUN_COMMS_TMO) {
+		/*
+		 * Modem timeout: was it really ready or just noise?
+		 * Revert to waiting for handshake to start.
+		 */
+		ipc_util_deactivate_ss(context);
+		return ipc_sm_state(IPC_SM_SLW_TX_BOOTREQ);
+	} else {
+		return ipc_sm_state(IPC_SM_ACT_RX_BOOTRESP);
+	}
+}
+
+static u8 sm_act_rx_bootresp_enter(u8 event, struct ipc_link_context *context)
+{
+	int err;
+
+	/* slave is ready - start the spi transfer */
+	dev_dbg(&context->sdev->dev,
+		"link %d: starting spi tfr\n", context->link->id);
+	err = spi_async(context->sdev, &context->spi_message);
+	if (err < 0) {
+		dev_err(&context->sdev->dev,
+			"link %d error: spi tfr start failed, error %d\n",
+			context->link->id, err);
+		return IPC_SM_RUN_ABORT;
+	}
+	return IPC_SM_RUN_NONE;
+}
+
+static const struct ipc_sm_state *sm_act_rx_bootresp_exit(u8 event,
+	struct ipc_link_context *context)
+{
+	u8 cmd_type = ipc_util_get_l1_cmd(context->cmd);
+	u8 modem_ver;
+
+	dev_dbg(&context->sdev->dev,
+		"link %d: RX HEADER %08x (type %d)\n",
+		context->link->id, context->cmd, cmd_type);
+
+	if (cmd_type == CMD_BOOTRESP) {
+		modem_ver = ipc_util_get_l1_bootresp_ver(context->cmd);
+
+		dev_info(&context->sdev->dev,
+			"link %d: boot sync done; "
+			"APE version %02x, MODEM version %02x\n",
+			context->link->id, IPC_DRIVER_VERSION, modem_ver);
+
+		/* check for minimum required modem version */
+		if (modem_ver < IPC_DRIVER_MODEM_MIN_VER) {
+			dev_warn(&context->sdev->dev,
+				"link %d warning: modem version mismatch! "
+				"minimum required version is %02x\n",
+				context->link->id,
+				IPC_DRIVER_MODEM_MIN_VER);
+		}
+
+		return ipc_sm_state(IPC_SM_WAIT_HANDSHAKE_INACTIVE);
+	} else {
+		/* invalid response... this is not our slave */
+		dev_err(&context->sdev->dev,
+			"link %d error: expected %x (BOOTRESP), received %x.\n",
+			context->link->id,
+			CMD_BOOTRESP,
+			cmd_type);
+		return ipc_sm_state(IPC_SM_HALT);
+	}
+}
+
+/* the driver protocol state machine */
+static const struct ipc_sm_state state_machine[IPC_SM_STATE_ID_NBR] = {
+	[IPC_SM_INIT] = {
+		.id     = IPC_SM_INIT,
+		.enter  = sm_init_enter,
+		.exit   = sm_init_exit,
+		.events = IPC_SM_RUN_INIT | IPC_SM_RUN_RESET
+	},
+	[IPC_SM_HALT] = {
+		.id     = IPC_SM_HALT,
+		.enter  = sm_halt_enter,
+		.exit   = sm_halt_exit,
+		.events = IPC_SM_RUN_RESET
+	},
+	[IPC_SM_RESET] = {
+		.id     = IPC_SM_RESET,
+		.enter  = sm_reset_enter,
+		.exit   = sm_reset_exit,
+		.events = IPC_SM_RUN_RESET
+	},
+	[IPC_SM_WAIT_SLAVE_STABLE] = {
+		.id     = IPC_SM_WAIT_SLAVE_STABLE,
+		.enter  = sm_wait_slave_stable_enter,
+		.exit   = sm_wait_slave_stable_exit,
+		.events = IPC_SM_RUN_STABLE_TMO
+	},
+	[IPC_SM_WAIT_HANDSHAKE_INACTIVE] = {
+		.id     = IPC_SM_WAIT_HANDSHAKE_INACTIVE,
+		.enter  = sm_wait_handshake_inactive_enter,
+		.exit   = sm_wait_handshake_inactive_exit,
+		.events = IPC_SM_RUN_STABLE_TMO
+	},
+	[IPC_SM_SLW_TX_BOOTREQ] = {
+		.id     = IPC_SM_SLW_TX_BOOTREQ,
+		.enter  = sm_slw_tx_bootreq_enter,
+		.exit   = sm_slw_tx_bootreq_exit,
+		.events = IPC_SM_RUN_SLAVE_IRQ
+	},
+	[IPC_SM_ACT_TX_BOOTREQ] = {
+		.id     = IPC_SM_ACT_TX_BOOTREQ,
+		.enter  = sm_act_tx_bootreq_enter,
+		.exit   = sm_act_tx_bootreq_exit,
+		.events = IPC_SM_RUN_TFR_COMPLETE
+	},
+	[IPC_SM_SLW_RX_BOOTRESP] = {
+		.id     = IPC_SM_SLW_RX_BOOTRESP,
+		.enter  = sm_slw_rx_bootresp_enter,
+		.exit   = sm_slw_rx_bootresp_exit,
+		.events = IPC_SM_RUN_SLAVE_IRQ | IPC_SM_RUN_COMMS_TMO
+	},
+	[IPC_SM_ACT_RX_BOOTRESP] = {
+		.id     = IPC_SM_ACT_RX_BOOTRESP,
+		.enter  = sm_act_rx_bootresp_enter,
+		.exit   = sm_act_rx_bootresp_exit,
+		.events = IPC_SM_RUN_TFR_COMPLETE
+	},
+	[IPC_SM_IDL] = {
+		.id     = IPC_SM_IDL,
+		.enter  = sm_idl_enter,
+		.exit   = sm_idl_exit,
+		.events = IPC_SM_RUN_SLAVE_IRQ | IPC_SM_RUN_TX_REQ |
+				IPC_SM_RUN_RESET
+	},
+	[IPC_SM_SLW_TX_WR_CMD] = {
+		.id     = IPC_SM_SLW_TX_WR_CMD,
+		.enter  = sm_slw_tx_wr_cmd_enter,
+		.exit   = sm_slw_tx_wr_cmd_exit,
+		.events = IPC_SM_RUN_SLAVE_IRQ | IPC_SM_RUN_COMMS_TMO |
+				IPC_SM_RUN_RESET
+	},
+	[IPC_SM_ACT_TX_WR_CMD] = {
+		.id     = IPC_SM_ACT_TX_WR_CMD,
+		.enter  = sm_act_tx_wr_cmd_enter,
+		.exit   = sm_act_tx_wr_cmd_exit,
+		.events = IPC_SM_RUN_TFR_COMPLETE | IPC_SM_RUN_RESET
+	},
+	[IPC_SM_SLW_TX_WR_DAT] = {
+		.id     = IPC_SM_SLW_TX_WR_DAT,
+		.enter  = sm_slw_tx_wr_dat_enter,
+		.exit   = sm_slw_tx_wr_dat_exit,
+		.events = IPC_SM_RUN_SLAVE_IRQ | IPC_SM_RUN_COMMS_TMO |
+				IPC_SM_RUN_RESET
+	},
+	[IPC_SM_ACT_TX_WR_DAT] = {
+		.id     = IPC_SM_ACT_TX_WR_DAT,
+		.enter  = sm_act_tx_wr_dat_enter,
+		.exit   = sm_act_tx_wr_dat_exit,
+		.events = IPC_SM_RUN_TFR_COMPLETE | IPC_SM_RUN_RESET
+	},
+	[IPC_SM_SLW_TX_RD_CMD] = {
+		.id     = IPC_SM_SLW_TX_RD_CMD,
+		.enter  = sm_slw_tx_rd_cmd_enter,
+		.exit   = sm_slw_tx_rd_cmd_exit,
+		.events = IPC_SM_RUN_SLAVE_IRQ | IPC_SM_RUN_COMMS_TMO |
+				IPC_SM_RUN_RESET
+	},
+	[IPC_SM_ACT_TX_RD_CMD] = {
+		.id     = IPC_SM_ACT_TX_RD_CMD,
+		.enter  = sm_act_tx_rd_cmd_enter,
+		.exit   = sm_act_tx_rd_cmd_exit,
+		.events = IPC_SM_RUN_TFR_COMPLETE | IPC_SM_RUN_RESET
+	},
+	[IPC_SM_SLW_RX_WR_CMD] = {
+		.id     = IPC_SM_SLW_RX_WR_CMD,
+		.enter  = sm_slw_rx_wr_cmd_enter,
+		.exit   = sm_slw_rx_wr_cmd_exit,
+		.events = IPC_SM_RUN_SLAVE_IRQ | IPC_SM_RUN_COMMS_TMO |
+				IPC_SM_RUN_RESET
+	},
+	[IPC_SM_ACT_RX_WR_CMD] = {
+		.id     = IPC_SM_ACT_RX_WR_CMD,
+		.enter  = sm_act_rx_wr_cmd_enter,
+		.exit   = sm_act_rx_wr_cmd_exit,
+		.events = IPC_SM_RUN_TFR_COMPLETE | IPC_SM_RUN_RESET
+	},
+	[IPC_SM_ACT_RX_WR_DAT] = {
+		.id     = IPC_SM_ACT_RX_WR_DAT,
+		.enter  = sm_act_rx_wr_dat_enter,
+		.exit   = sm_act_rx_wr_dat_exit,
+		.events = IPC_SM_RUN_TFR_COMPLETE | IPC_SM_RUN_RESET
+	},
+	/* audio link states below */
+	[IPC_SM_INIT_AUD] = {
+		.id     = IPC_SM_INIT_AUD,
+		.enter  = sm_init_enter,
+		.exit   = sm_init_aud_exit,
+		.events = IPC_SM_RUN_INIT | IPC_SM_RUN_RESET
+	},
+	[IPC_SM_HALT_AUD] = {
+		.id     = IPC_SM_HALT_AUD,
+		.enter  = sm_halt_enter,
+		.exit   = sm_halt_aud_exit,
+		.events = IPC_SM_RUN_RESET
+	},
+	[IPC_SM_RESET_AUD] = {
+		.id     = IPC_SM_RESET_AUD,
+		.enter  = sm_reset_enter,
+		.exit   = sm_reset_aud_exit,
+		.events = IPC_SM_RUN_RESET
+	},
+	[IPC_SM_IDL_AUD] = {
+		.id     = IPC_SM_IDL_AUD,
+		.enter  = sm_idl_enter,
+		.exit   = sm_idl_aud_exit,
+		.events = IPC_SM_RUN_SLAVE_IRQ | IPC_SM_RUN_TX_REQ |
+				IPC_SM_RUN_RESET
+	},
+	[IPC_SM_SLW_TX_WR_DAT_AUD] = {
+		.id     = IPC_SM_SLW_TX_WR_DAT_AUD,
+		.enter  = sm_slw_tx_wr_dat_aud_enter,
+		.exit   = sm_slw_tx_wr_dat_aud_exit,
+		.events = IPC_SM_RUN_SLAVE_IRQ | IPC_SM_RUN_COMMS_TMO |
+				IPC_SM_RUN_RESET
+	},
+	[IPC_SM_ACT_TX_WR_DAT_AUD] = {
+		.id     = IPC_SM_ACT_TX_WR_DAT_AUD,
+		.enter  = sm_act_tx_wr_dat_enter,
+		.exit   = sm_act_tx_wr_dat_aud_exit,
+		.events = IPC_SM_RUN_TFR_COMPLETE | IPC_SM_RUN_RESET
+	},
+	[IPC_SM_SLW_RX_WR_DAT_AUD] = {
+		.id     = IPC_SM_SLW_RX_WR_DAT_AUD,
+		.enter  = sm_slw_rx_wr_dat_aud_enter,
+		.exit   = sm_slw_rx_wr_dat_aud_exit,
+		.events = IPC_SM_RUN_SLAVE_IRQ | IPC_SM_RUN_COMMS_TMO |
+			IPC_SM_RUN_RESET
+	},
+	[IPC_SM_ACT_RX_WR_DAT_AUD] = {
+		.id     = IPC_SM_ACT_RX_WR_DAT_AUD,
+		.enter  = sm_act_rx_wr_dat_aud_enter,
+		.exit   = sm_act_rx_wr_dat_aud_exit,
+		.events = IPC_SM_RUN_TFR_COMPLETE | IPC_SM_RUN_RESET
+	}
+};
+
+
+const struct ipc_sm_state *ipc_sm_idle_state(struct ipc_link_context *context)
+{
+	if (context->link->id == IPC_LINK_AUDIO)
+		return ipc_sm_state(IPC_SM_IDL_AUD);
+	else
+		return ipc_sm_state(IPC_SM_IDL);
+}
+
+const struct ipc_sm_state *ipc_sm_init_state(struct ipc_link_context *context)
+{
+	if (context->link->id == IPC_LINK_AUDIO)
+		return ipc_sm_state(IPC_SM_INIT_AUD);
+	else
+		return ipc_sm_state(IPC_SM_INIT);
+}
+
+const struct ipc_sm_state *ipc_sm_state(u8 id)
+{
+	BUG_ON(id >= IPC_SM_STATE_ID_NBR);
+	return &state_machine[id];
+}
+
+bool ipc_sm_valid_for_state(u8 event, const struct ipc_sm_state *state)
+{
+	return (state->events & event) == event;
+}
+
+static void state_machine_run(struct ipc_link_context *context, u8 event)
+{
+	struct modem_m6718_spi_link_platform_data *link = context->link;
+	struct spi_device *sdev = context->sdev;
+	const struct ipc_sm_state *cur_state = context->state;
+
+	/* some sanity checking */
+	if (context == NULL || link == NULL || cur_state == NULL) {
+		pr_err("M6718 IPC protocol error: "
+			"inconsistent driver state, ignoring event\n");
+		return;
+	}
+
+	dev_dbg(&sdev->dev, "link %d: RUNNING in %s (%s)\n", link->id,
+		ipc_dbg_state_id(cur_state), ipc_dbg_event(event));
+
+	/* valid trigger event for current state? */
+	if (!ipc_sm_valid_for_state(event, cur_state)) {
+		dev_dbg(&sdev->dev,
+			"link %d: ignoring invalid event\n", link->id);
+		ipc_dbg_ignoring_event(context, event);
+		return;
+	}
+	ipc_dbg_handling_event(context, event);
+
+	/* run machine while state entry functions trigger new changes */
+	do {
+		if (event == IPC_SM_RUN_SLAVE_IRQ &&
+			!ipc_util_int_is_active(context)) {
+			dev_err(&sdev->dev,
+				"link %d error: slave is not ready! (%s)",
+				link->id,
+				ipc_dbg_state_id(cur_state));
+		}
+
+		if (event == IPC_SM_RUN_ABORT) {
+			dev_err(&sdev->dev,
+				"link %d error: abort event\n", link->id);
+			/* reset state to idle */
+			context->state = ipc_sm_idle_state(context);
+			break;
+		} else {
+			/* exit current state */
+			dev_dbg(&sdev->dev, "link %d: exit %s (%s)\n",
+				link->id, ipc_dbg_state_id(cur_state),
+				ipc_dbg_event(event));
+			cur_state = cur_state->exit(event, context);
+			context->state = cur_state;
+		}
+
+		/* reset state of slave irq to prepare for next event */
+		if (event == IPC_SM_RUN_SLAVE_IRQ)
+			atomic_set(&context->state_int, 0);
+
+		/* enter new state */
+		dev_dbg(&sdev->dev, "link %d: enter %s (%s)\n", link->id,
+			ipc_dbg_state_id(cur_state), ipc_dbg_event(event));
+		event = context->state->enter(event, context);
+		ipc_dbg_entering_state(context);
+	} while (event != IPC_SM_RUN_NONE);
+
+	dev_dbg(&sdev->dev, "link %d: STOPPED in %s\n", link->id,
+		ipc_dbg_state_id(cur_state));
+}
+
+void ipc_sm_kick(u8 event, struct ipc_link_context *context)
+{
+	unsigned long flags;
+	struct modem_m6718_spi_link_platform_data *link = context->link;
+	struct spi_device *sdev = context->sdev;
+	struct spi_message *msg = &context->spi_message;
+	u8 i;
+
+	spin_lock_irqsave(&context->sm_lock, flags);
+	switch (event) {
+	case IPC_SM_RUN_SLAVE_IRQ:
+		dev_dbg(&sdev->dev,
+			"link %d EVENT: slave-ready irq\n", link->id);
+		del_timer(&context->comms_timer);
+		atomic_set(&context->state_int,
+			ipc_util_int_is_active(context));
+		break;
+
+	case IPC_SM_RUN_TFR_COMPLETE:
+		dev_dbg(&sdev->dev,
+			"link %d EVENT: spi tfr complete (status %d len %d)\n",
+			link->id, msg->status, msg->actual_length);
+		ipc_dbg_dump_spi_tfr(context);
+		break;
+
+	case IPC_SM_RUN_COMMS_TMO:
+	{
+		char *statestr;
+		struct ipc_link_context *contexts = l1_context.device_context;
+
+		statestr = ipc_dbg_link_state_str(context);
+		dev_err(&sdev->dev,
+			"link %d EVENT: modem comms timeout (%s)!\n",
+			link->id, ipc_dbg_state_id(context->state));
+		if (statestr != NULL) {
+			dev_err(&sdev->dev, "%s", statestr);
+			kfree(statestr);
+		}
+
+		/* cancel all link timeout timers except this one */
+		for (i = 0; i < IPC_NBR_SUPPORTED_SPI_LINKS; i++)
+			if (contexts[i].link->id != link->id)
+				del_timer(&contexts[i].comms_timer);
+		break;
+	}
+
+	case IPC_SM_RUN_STABLE_TMO:
+		dev_dbg(&sdev->dev,
+			"link %d EVENT: slave-stable timeout\n", link->id);
+		break;
+
+	case IPC_SM_RUN_RESET:
+		dev_dbg(&sdev->dev,
+			"link %d EVENT: reset\n", link->id);
+		del_timer(&context->comms_timer);
+		break;
+
+	default:
+		break;
+	}
+
+	state_machine_run(context, event);
+	spin_unlock_irqrestore(&context->sm_lock, flags);
+}
+