ASoC: SOF: Introduce IPC SOF client support

A client in the SOF (Sound Open Firmware) context is a driver that needs
to communicate with the DSP via IPC messages. The SOF core is responsible
for serializing the IPC messages to the DSP from the different clients.

One example of an SOF client would be an IPC test client that floods the
DSP with test IPC messages to validate if the serialization works as
expected.

Multi-client support will also add the ability to split the existing audio
cards into multiple ones, so as to e.g. to deal with HDMI with a dedicated
client instead of adding HDMI to all cards.

This patch introduces descriptors for SOF client driver and SOF client
device along with APIs for registering and unregistering a SOF client
driver, sending IPCs from a client device and accessing the SOF core
debugfs root entry.

Along with this, add a couple of new members to struct snd_sof_dev that
will be used for maintaining the list of clients.
Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Co-developed-by: Fred Oh <fred.oh@linux.intel.com>
Signed-off-by: Fred Oh <fred.oh@linux.intel.com>
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Link: https://lore.kernel.org/r/20220210150525.30756-6-peter.ujfalusi@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sof/Kconfig

@@ -61,6 +61,13 @@ config SND_SOC_SOF_DEBUG_PROBES
 	  Say Y if you want to enable probes.
 	  If unsure, select "N".
 
+config SND_SOC_SOF_CLIENT
+	tristate
+	select AUXILIARY_BUS
+	help
+	  This option is not user-selectable but automagically handled by
+	  'select' statements at a higher level.
+
 config SND_SOC_SOF_DEVELOPER_SUPPORT
 	bool "SOF developer options support"
 	depends on EXPERT && SND_SOC_SOF

sound/soc/sof/Makefile

@@ -2,6 +2,7 @@
 
 snd-sof-objs := core.o ops.o loader.o ipc.o pcm.o pm.o debug.o topology.o\
 		control.o trace.o iomem-utils.o sof-audio.o stream-ipc.o
+snd-sof-$(CONFIG_SND_SOC_SOF_CLIENT) += sof-client.o
 
 snd-sof-$(CONFIG_SND_SOC_SOF_DEBUG_PROBES) += sof-probes.o
 snd-sof-$(CONFIG_SND_SOC_SOF_COMPRESS) += compress.o

sound/soc/sof/core.c

@@ -122,6 +122,27 @@ void sof_print_oops_and_stack(struct snd_sof_dev *sdev, const char *level,
 }
 EXPORT_SYMBOL(sof_print_oops_and_stack);
 
+/* Helper to manage DSP state */
+void sof_set_fw_state(struct snd_sof_dev *sdev, enum sof_fw_state new_state)
+{
+	if (sdev->fw_state == new_state)
+		return;
+
+	dev_dbg(sdev->dev, "fw_state change: %d -> %d\n", sdev->fw_state, new_state);
+	sdev->fw_state = new_state;
+
+	switch (new_state) {
+	case SOF_FW_BOOT_NOT_STARTED:
+	case SOF_FW_BOOT_COMPLETE:
+	case SOF_FW_CRASHED:
+		sof_client_fw_state_dispatcher(sdev);
+		fallthrough;
+	default:
+		break;
+	}
+}
+EXPORT_SYMBOL(sof_set_fw_state);
+
 /*
  *			FW Boot State Transition Diagram
  *
@@ -266,6 +287,12 @@ static int sof_probe_continue(struct snd_sof_dev *sdev)
 		goto fw_trace_err;
 	}
 
+	ret = sof_register_clients(sdev);
+	if (ret < 0) {
+		dev_err(sdev->dev, "failed to register clients %d\n", ret);
+		goto sof_machine_err;
+	}
+
 	/*
 	 * Some platforms in SOF, ex: BYT, may not have their platform PM
 	 * callbacks set. Increment the usage count so as to
@@ -281,6 +308,8 @@ static int sof_probe_continue(struct snd_sof_dev *sdev)
 
 	return 0;
 
+sof_machine_err:
+	snd_sof_machine_unregister(sdev, plat_data);
 fw_trace_err:
 	snd_sof_free_trace(sdev);
 fw_run_err:
@@ -329,7 +358,6 @@ int snd_sof_device_probe(struct device *dev, struct snd_sof_pdata *plat_data)
 
 	sdev->pdata = plat_data;
 	sdev->first_boot = true;
-	sof_set_fw_state(sdev, SOF_FW_BOOT_NOT_STARTED);
 #if IS_ENABLED(CONFIG_SND_SOC_SOF_DEBUG_PROBES)
 	sdev->extractor_stream_tag = SOF_PROBE_INVALID_NODE_ID;
 #endif
@@ -350,9 +378,14 @@ int snd_sof_device_probe(struct device *dev, struct snd_sof_pdata *plat_data)
 	INIT_LIST_HEAD(&sdev->widget_list);
 	INIT_LIST_HEAD(&sdev->dai_list);
 	INIT_LIST_HEAD(&sdev->route_list);
+	INIT_LIST_HEAD(&sdev->ipc_client_list);
+	INIT_LIST_HEAD(&sdev->ipc_rx_handler_list);
+	INIT_LIST_HEAD(&sdev->fw_state_handler_list);
 	spin_lock_init(&sdev->ipc_lock);
 	spin_lock_init(&sdev->hw_lock);
 	mutex_init(&sdev->power_state_access);
+	mutex_init(&sdev->ipc_client_mutex);
+	mutex_init(&sdev->client_event_handler_mutex);
 
 	/* set default timeouts if none provided */
 	if (plat_data->desc->ipc_timeout == 0)
@@ -364,6 +397,8 @@ int snd_sof_device_probe(struct device *dev, struct snd_sof_pdata *plat_data)
 	else
 		sdev->boot_timeout = plat_data->desc->boot_timeout;
 
+	sof_set_fw_state(sdev, SOF_FW_BOOT_NOT_STARTED);
+
 	if (IS_ENABLED(CONFIG_SND_SOC_SOF_PROBE_WORK_QUEUE)) {
 		INIT_WORK(&sdev->probe_work, sof_probe_work);
 		schedule_work(&sdev->probe_work);
@@ -391,6 +426,12 @@ int snd_sof_device_remove(struct device *dev)
 	if (IS_ENABLED(CONFIG_SND_SOC_SOF_PROBE_WORK_QUEUE))
 		cancel_work_sync(&sdev->probe_work);
 
+	/*
+	 * Unregister any registered client device first before IPC and debugfs
+	 * to allow client drivers to be removed cleanly
+	 */
+	sof_unregister_clients(sdev);
+
 	/*
 	 * Unregister machine driver. This will unbind the snd_card which
 	 * will remove the component driver and unload the topology

sound/soc/sof/ipc.c

@@ -557,22 +557,25 @@ void snd_sof_ipc_msgs_rx(struct snd_sof_dev *sdev)
 		break;
 	}
 
-	if (rx_callback) {
-		/* read the full message as we have rx handler for it */
-		msg_buf = kmalloc(hdr.size, GFP_KERNEL);
-		if (!msg_buf)
-			return;
+	/* read the full message */
+	msg_buf = kmalloc(hdr.size, GFP_KERNEL);
+	if (!msg_buf)
+		return;
 
-		err = snd_sof_ipc_msg_data(sdev, NULL, msg_buf, hdr.size);
-		if (err < 0)
-			dev_err(sdev->dev, "%s: Failed to read message: %d\n",
-				__func__, err);
-		else
+	err = snd_sof_ipc_msg_data(sdev, NULL, msg_buf, hdr.size);
+	if (err < 0) {
+		dev_err(sdev->dev, "%s: Failed to read message: %d\n", __func__, err);
+	} else {
+		/* Call local handler for the message */
+		if (rx_callback)
 			rx_callback(sdev, msg_buf);
 
-		kfree(msg_buf);
+		/* Notify registered clients */
+		sof_client_ipc_rx_dispatcher(sdev, msg_buf);
 	}
 
+	kfree(msg_buf);
+
 	ipc_log_header(sdev->dev, "ipc rx done", hdr.cmd);
 }
 EXPORT_SYMBOL(snd_sof_ipc_msgs_rx);

sound/soc/sof/sof-client.c

+// SPDX-License-Identifier: GPL-2.0-only
+//
+// Copyright(c) 2022 Intel Corporation. All rights reserved.
+//
+// Authors: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
+//	    Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
+//
+
+#include <linux/debugfs.h>
+#include <linux/errno.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include "ops.h"
+#include "sof-client.h"
+#include "sof-priv.h"
+
+/**
+ * struct sof_ipc_event_entry - IPC client event description
+ * @ipc_msg_type:	IPC msg type of the event the client is interested
+ * @cdev:		sof_client_dev of the requesting client
+ * @callback:		Callback function of the client
+ * @list:		item in SOF core client event list
+ */
+struct sof_ipc_event_entry {
+	u32 ipc_msg_type;
+	struct sof_client_dev *cdev;
+	sof_client_event_callback callback;
+	struct list_head list;
+};
+
+/**
+ * struct sof_state_event_entry - DSP panic event subscription entry
+ * @cdev:		sof_client_dev of the requesting client
+ * @callback:		Callback function of the client
+ * @list:		item in SOF core client event list
+ */
+struct sof_state_event_entry {
+	struct sof_client_dev *cdev;
+	sof_client_fw_state_callback callback;
+	struct list_head list;
+};
+
+static void sof_client_auxdev_release(struct device *dev)
+{
+	struct auxiliary_device *auxdev = to_auxiliary_dev(dev);
+	struct sof_client_dev *cdev = auxiliary_dev_to_sof_client_dev(auxdev);
+
+	kfree(cdev->auxdev.dev.platform_data);
+	kfree(cdev);
+}
+
+static int sof_client_dev_add_data(struct sof_client_dev *cdev, const void *data,
+				   size_t size)
+{
+	void *d = NULL;
+
+	if (data) {
+		d = kmemdup(data, size, GFP_KERNEL);
+		if (!d)
+			return -ENOMEM;
+	}
+
+	cdev->auxdev.dev.platform_data = d;
+	return 0;
+}
+
+int sof_register_clients(struct snd_sof_dev *sdev)
+{
+	if (sof_ops(sdev) && sof_ops(sdev)->register_ipc_clients)
+		return sof_ops(sdev)->register_ipc_clients(sdev);
+
+	return 0;
+}
+
+void sof_unregister_clients(struct snd_sof_dev *sdev)
+{
+	if (sof_ops(sdev) && sof_ops(sdev)->unregister_ipc_clients)
+		sof_ops(sdev)->unregister_ipc_clients(sdev);
+}
+
+int sof_client_dev_register(struct snd_sof_dev *sdev, const char *name, u32 id,
+			    const void *data, size_t size)
+{
+	struct auxiliary_device *auxdev;
+	struct sof_client_dev *cdev;
+	int ret;
+
+	cdev = kzalloc(sizeof(*cdev), GFP_KERNEL);
+	if (!cdev)
+		return -ENOMEM;
+
+	cdev->sdev = sdev;
+	auxdev = &cdev->auxdev;
+	auxdev->name = name;
+	auxdev->dev.parent = sdev->dev;
+	auxdev->dev.release = sof_client_auxdev_release;
+	auxdev->id = id;
+
+	ret = sof_client_dev_add_data(cdev, data, size);
+	if (ret < 0)
+		goto err_dev_add_data;
+
+	ret = auxiliary_device_init(auxdev);
+	if (ret < 0) {
+		dev_err(sdev->dev, "failed to initialize client dev %s.%d\n", name, id);
+		goto err_dev_init;
+	}
+
+	ret = auxiliary_device_add(&cdev->auxdev);
+	if (ret < 0) {
+		dev_err(sdev->dev, "failed to add client dev %s.%d\n", name, id);
+		/*
+		 * sof_client_auxdev_release() will be invoked to free up memory
+		 * allocations through put_device()
+		 */
+		auxiliary_device_uninit(&cdev->auxdev);
+		return ret;
+	}
+
+	/* add to list of SOF client devices */
+	mutex_lock(&sdev->ipc_client_mutex);
+	list_add(&cdev->list, &sdev->ipc_client_list);
+	mutex_unlock(&sdev->ipc_client_mutex);
+
+	return 0;
+
+err_dev_init:
+	kfree(cdev->auxdev.dev.platform_data);
+
+err_dev_add_data:
+	kfree(cdev);
+
+	return ret;
+}
+EXPORT_SYMBOL_NS_GPL(sof_client_dev_register, SND_SOC_SOF_CLIENT);
+
+void sof_client_dev_unregister(struct snd_sof_dev *sdev, const char *name, u32 id)
+{
+	struct sof_client_dev *cdev;
+
+	mutex_lock(&sdev->ipc_client_mutex);
+
+	/*
+	 * sof_client_auxdev_release() will be invoked to free up memory
+	 * allocations through put_device()
+	 */
+	list_for_each_entry(cdev, &sdev->ipc_client_list, list) {
+		if (!strcmp(cdev->auxdev.name, name) && cdev->auxdev.id == id) {
+			list_del(&cdev->list);
+			auxiliary_device_delete(&cdev->auxdev);
+			auxiliary_device_uninit(&cdev->auxdev);
+			break;
+		}
+	}
+
+	mutex_unlock(&sdev->ipc_client_mutex);
+}
+EXPORT_SYMBOL_NS_GPL(sof_client_dev_unregister, SND_SOC_SOF_CLIENT);
+
+int sof_client_ipc_tx_message(struct sof_client_dev *cdev, void *ipc_msg,
+			      void *reply_data, size_t reply_bytes)
+{
+	struct sof_ipc_cmd_hdr *hdr = ipc_msg;
+
+	return sof_ipc_tx_message(cdev->sdev->ipc, hdr->cmd, ipc_msg, hdr->size,
+				  reply_data, reply_bytes);
+}
+EXPORT_SYMBOL_NS_GPL(sof_client_ipc_tx_message, SND_SOC_SOF_CLIENT);
+
+struct dentry *sof_client_get_debugfs_root(struct sof_client_dev *cdev)
+{
+	return cdev->sdev->debugfs_root;
+}
+EXPORT_SYMBOL_NS_GPL(sof_client_get_debugfs_root, SND_SOC_SOF_CLIENT);
+
+/* DMA buffer allocation in client drivers must use the core SOF device */
+struct device *sof_client_get_dma_dev(struct sof_client_dev *cdev)
+{
+	return cdev->sdev->dev;
+}
+EXPORT_SYMBOL_NS_GPL(sof_client_get_dma_dev, SND_SOC_SOF_CLIENT);
+
+const struct sof_ipc_fw_version *sof_client_get_fw_version(struct sof_client_dev *cdev)
+{
+	struct snd_sof_dev *sdev = sof_client_dev_to_sof_dev(cdev);
+
+	return &sdev->fw_ready.version;
+}
+EXPORT_SYMBOL_NS_GPL(sof_client_get_fw_version, SND_SOC_SOF_CLIENT);
+
+/* module refcount management of SOF core */
+int sof_client_core_module_get(struct sof_client_dev *cdev)
+{
+	struct snd_sof_dev *sdev = sof_client_dev_to_sof_dev(cdev);
+
+	if (!try_module_get(sdev->dev->driver->owner))
+		return -ENODEV;
+
+	return 0;
+}
+EXPORT_SYMBOL_NS_GPL(sof_client_core_module_get, SND_SOC_SOF_CLIENT);
+
+void sof_client_core_module_put(struct sof_client_dev *cdev)
+{
+	struct snd_sof_dev *sdev = sof_client_dev_to_sof_dev(cdev);
+
+	module_put(sdev->dev->driver->owner);
+}
+EXPORT_SYMBOL_NS_GPL(sof_client_core_module_put, SND_SOC_SOF_CLIENT);
+
+/* IPC event handling */
+void sof_client_ipc_rx_dispatcher(struct snd_sof_dev *sdev, void *msg_buf)
+{
+	struct sof_ipc_cmd_hdr *hdr = msg_buf;
+	u32 msg_type = hdr->cmd & SOF_GLB_TYPE_MASK;
+	struct sof_ipc_event_entry *event;
+
+	mutex_lock(&sdev->client_event_handler_mutex);
+
+	list_for_each_entry(event, &sdev->ipc_rx_handler_list, list) {
+		if (event->ipc_msg_type == msg_type)
+			event->callback(event->cdev, msg_buf);
+	}
+
+	mutex_unlock(&sdev->client_event_handler_mutex);
+}
+
+int sof_client_register_ipc_rx_handler(struct sof_client_dev *cdev,
+				       u32 ipc_msg_type,
+				       sof_client_event_callback callback)
+{
+	struct snd_sof_dev *sdev = sof_client_dev_to_sof_dev(cdev);
+	struct sof_ipc_event_entry *event;
+
+	if (!callback || !(ipc_msg_type & SOF_GLB_TYPE_MASK))
+		return -EINVAL;
+
+	event = kmalloc(sizeof(*event), GFP_KERNEL);
+	if (!event)
+		return -ENOMEM;
+
+	event->ipc_msg_type = ipc_msg_type;
+	event->cdev = cdev;
+	event->callback = callback;
+
+	/* add to list of SOF client devices */
+	mutex_lock(&sdev->client_event_handler_mutex);
+	list_add(&event->list, &sdev->ipc_rx_handler_list);
+	mutex_unlock(&sdev->client_event_handler_mutex);
+
+	return 0;
+}
+EXPORT_SYMBOL_NS_GPL(sof_client_register_ipc_rx_handler, SND_SOC_SOF_CLIENT);
+
+void sof_client_unregister_ipc_rx_handler(struct sof_client_dev *cdev,
+					  u32 ipc_msg_type)
+{
+	struct snd_sof_dev *sdev = sof_client_dev_to_sof_dev(cdev);
+	struct sof_ipc_event_entry *event;
+
+	mutex_lock(&sdev->client_event_handler_mutex);
+
+	list_for_each_entry(event, &sdev->ipc_rx_handler_list, list) {
+		if (event->cdev == cdev && event->ipc_msg_type == ipc_msg_type) {
+			list_del(&event->list);
+			kfree(event);
+			break;
+		}
+	}
+
+	mutex_unlock(&sdev->client_event_handler_mutex);
+}
+EXPORT_SYMBOL_NS_GPL(sof_client_unregister_ipc_rx_handler, SND_SOC_SOF_CLIENT);
+
+/*DSP state notification and query */
+void sof_client_fw_state_dispatcher(struct snd_sof_dev *sdev)
+{
+	struct sof_state_event_entry *event;
+
+	mutex_lock(&sdev->client_event_handler_mutex);
+
+	list_for_each_entry(event, &sdev->fw_state_handler_list, list)
+		event->callback(event->cdev, sdev->fw_state);
+
+	mutex_unlock(&sdev->client_event_handler_mutex);
+}
+
+int sof_client_register_fw_state_handler(struct sof_client_dev *cdev,
+					 sof_client_fw_state_callback callback)
+{
+	struct snd_sof_dev *sdev = sof_client_dev_to_sof_dev(cdev);
+	struct sof_state_event_entry *event;
+
+	if (!callback)
+		return -EINVAL;
+
+	event = kmalloc(sizeof(*event), GFP_KERNEL);
+	if (!event)
+		return -ENOMEM;
+
+	event->cdev = cdev;
+	event->callback = callback;
+
+	/* add to list of SOF client devices */
+	mutex_lock(&sdev->client_event_handler_mutex);
+	list_add(&event->list, &sdev->fw_state_handler_list);
+	mutex_unlock(&sdev->client_event_handler_mutex);
+
+	return 0;
+}
+EXPORT_SYMBOL_NS_GPL(sof_client_register_fw_state_handler, SND_SOC_SOF_CLIENT);
+
+void sof_client_unregister_fw_state_handler(struct sof_client_dev *cdev)
+{
+	struct snd_sof_dev *sdev = sof_client_dev_to_sof_dev(cdev);
+	struct sof_state_event_entry *event;
+
+	mutex_lock(&sdev->client_event_handler_mutex);
+
+	list_for_each_entry(event, &sdev->fw_state_handler_list, list) {
+		if (event->cdev == cdev) {
+			list_del(&event->list);
+			kfree(event);
+			break;
+		}
+	}
+
+	mutex_unlock(&sdev->client_event_handler_mutex);
+}
+EXPORT_SYMBOL_NS_GPL(sof_client_unregister_fw_state_handler, SND_SOC_SOF_CLIENT);
+
+enum sof_fw_state sof_client_get_fw_state(struct sof_client_dev *cdev)
+{
+	struct snd_sof_dev *sdev = sof_client_dev_to_sof_dev(cdev);
+
+	return sdev->fw_state;
+}
+EXPORT_SYMBOL_NS_GPL(sof_client_get_fw_state, SND_SOC_SOF_CLIENT);

sound/soc/sof/sof-client.h

+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef __SOC_SOF_CLIENT_H
+#define __SOC_SOF_CLIENT_H
+
+#include <linux/auxiliary_bus.h>
+#include <linux/device.h>
+#include <linux/list.h>
+#include <sound/sof.h>
+
+struct sof_ipc_fw_version;
+struct sof_ipc_cmd_hdr;
+struct snd_sof_dev;
+struct dentry;
+
+/**
+ * struct sof_client_dev - SOF client device
+ * @auxdev:	auxiliary device
+ * @sdev:	pointer to SOF core device struct
+ * @list:	item in SOF core client dev list
+ * @data:	device specific data
+ */
+struct sof_client_dev {
+	struct auxiliary_device auxdev;
+	struct snd_sof_dev *sdev;
+	struct list_head list;
+	void *data;
+};
+
+#define sof_client_dev_to_sof_dev(cdev)		((cdev)->sdev)
+
+#define auxiliary_dev_to_sof_client_dev(auxiliary_dev) \
+	container_of(auxiliary_dev, struct sof_client_dev, auxdev)
+
+#define dev_to_sof_client_dev(dev) \
+	container_of(to_auxiliary_dev(dev), struct sof_client_dev, auxdev)
+
+int sof_client_ipc_tx_message(struct sof_client_dev *cdev, void *ipc_msg,
+			      void *reply_data, size_t reply_bytes);
+
+struct dentry *sof_client_get_debugfs_root(struct sof_client_dev *cdev);
+struct device *sof_client_get_dma_dev(struct sof_client_dev *cdev);
+const struct sof_ipc_fw_version *sof_client_get_fw_version(struct sof_client_dev *cdev);
+
+/* module refcount management of SOF core */
+int sof_client_core_module_get(struct sof_client_dev *cdev);
+void sof_client_core_module_put(struct sof_client_dev *cdev);
+
+/* IPC notification */
+typedef void (*sof_client_event_callback)(struct sof_client_dev *cdev, void *msg_buf);
+
+int sof_client_register_ipc_rx_handler(struct sof_client_dev *cdev,
+				       u32 ipc_msg_type,
+				       sof_client_event_callback callback);
+void sof_client_unregister_ipc_rx_handler(struct sof_client_dev *cdev,
+					  u32 ipc_msg_type);
+
+/* DSP state notification and query */
+typedef void (*sof_client_fw_state_callback)(struct sof_client_dev *cdev,
+					     enum sof_fw_state state);
+
+int sof_client_register_fw_state_handler(struct sof_client_dev *cdev,
+					 sof_client_fw_state_callback callback);
+void sof_client_unregister_fw_state_handler(struct sof_client_dev *cdev);
+enum sof_fw_state sof_client_get_fw_state(struct sof_client_dev *cdev);
+
+#endif /* __SOC_SOF_CLIENT_H */

sound/soc/sof/sof-priv.h

@@ -292,6 +292,10 @@ struct snd_sof_dsp_ops {
 	void (*set_mach_params)(struct snd_soc_acpi_mach *mach,
 				struct snd_sof_dev *sdev); /* optional */
 
+	/* IPC client ops */
+	int (*register_ipc_clients)(struct snd_sof_dev *sdev); /* optional */
+	void (*unregister_ipc_clients)(struct snd_sof_dev *sdev); /* optional */
+
 	/* DAI ops */
 	struct snd_soc_dai_driver *drv;
 	int num_drv;
@@ -479,6 +483,30 @@ struct snd_sof_dev {
 	 */
 	int dsp_core_ref_count[SOF_MAX_DSP_NUM_CORES];
 
+	/*
+	 * Used to keep track of registered IPC client devices so that they can
+	 * be removed when the parent SOF module is removed.
+	 */
+	struct list_head ipc_client_list;
+
+	/* mutex to protect client list */
+	struct mutex ipc_client_mutex;
+
+	/*
+	 * Used for tracking the IPC client's RX registration for DSP initiated
+	 * message handling.
+	 */
+	struct list_head ipc_rx_handler_list;
+
+	/*
+	 * Used for tracking the IPC client's registration for DSP state change
+	 * notification
+	 */
+	struct list_head fw_state_handler_list;
+
+	/* to protect the ipc_rx_handler_list  and  dsp_state_handler_list list */
+	struct mutex client_event_handler_mutex;
+
 	void *private;			/* core does not touch this */
 };
 
@@ -582,15 +610,7 @@ extern const struct dsp_arch_ops sof_xtensa_arch_ops;
 /*
  * Firmware state tracking
  */
-static inline void sof_set_fw_state(struct snd_sof_dev *sdev,
-				    enum sof_fw_state new_state)
-{
-	if (sdev->fw_state == new_state)
-		return;
-
-	dev_dbg(sdev->dev, "fw_state change: %d -> %d\n", sdev->fw_state, new_state);
-	sdev->fw_state = new_state;
-}
+void sof_set_fw_state(struct snd_sof_dev *sdev, enum sof_fw_state new_state);
 
 /*
  * Utilities
@@ -623,4 +643,44 @@ int sof_stream_pcm_close(struct snd_sof_dev *sdev,
 			 struct snd_pcm_substream *substream);
 
 int sof_machine_check(struct snd_sof_dev *sdev);
+
+/* SOF client support */
+#if IS_ENABLED(CONFIG_SND_SOC_SOF_CLIENT)
+int sof_client_dev_register(struct snd_sof_dev *sdev, const char *name, u32 id,
+			    const void *data, size_t size);
+void sof_client_dev_unregister(struct snd_sof_dev *sdev, const char *name, u32 id);
+int sof_register_clients(struct snd_sof_dev *sdev);
+void sof_unregister_clients(struct snd_sof_dev *sdev);
+void sof_client_ipc_rx_dispatcher(struct snd_sof_dev *sdev, void *msg_buf);
+void sof_client_fw_state_dispatcher(struct snd_sof_dev *sdev);
+#else /* CONFIG_SND_SOC_SOF_CLIENT */
+static inline int sof_client_dev_register(struct snd_sof_dev *sdev, const char *name,
+					  u32 id, const void *data, size_t size)
+{
+	return 0;
+}
+
+static inline void sof_client_dev_unregister(struct snd_sof_dev *sdev,
+					     const char *name, u32 id)
+{
+}
+
+static inline int sof_register_clients(struct snd_sof_dev *sdev)
+{
+	return 0;
+}
+
+static inline  void sof_unregister_clients(struct snd_sof_dev *sdev)
+{
+}
+
+static inline void sof_client_ipc_rx_dispatcher(struct snd_sof_dev *sdev, void *msg_buf)
+{
+}
+
+static inline void sof_client_fw_state_dispatcher(struct snd_sof_dev *sdev)
+{
+}
+#endif /* CONFIG_SND_SOC_SOF_CLIENT */
+
 #endif