[v3,1/8] i3c: add target mode support

diff --git a/drivers/i3c/Kconfig b/drivers/i3c/Kconfig
index 30a441506f61c..d59a7eb83d13a 100644
--- a/drivers/i3c/Kconfig
+++ b/drivers/i3c/Kconfig
@@ -10,7 +10,7 @@  menuconfig I3C
 	  support for high speed transfers and native interrupt support
 	  without the need for extra pins.
 
-	  The I3C protocol also standardizes the slave device types and is
+	  The I3C protocol also standardizes the target device types and is
 	  mainly designed to communicate with sensors.
 
 	  If you want I3C support, you should say Y here and also to the
@@ -22,3 +22,29 @@  menuconfig I3C
 if I3C
 source "drivers/i3c/master/Kconfig"
 endif # I3C
+
+config I3C_TARGET
+	bool "I3C Target Support"
+	help
+	  Support I3C Target Mode.
+
+	  Enable this configuration option to support configurable I3C target.
+	  This should be enabled if the platform has a I3C controller that can
+	  operate in target mode.
+
+	  Enabling this option will build the I3C target library, which includes
+	  target controller library and target function library.
+
+	  If in doubt, say "N" to disable target support.
+
+config I3C_TARGET_CONFIGFS
+	bool "I3C Target Configfs Support"
+	depends on I3C_TARGET
+	select CONFIGFS_FS
+	help
+	  Configfs entry for target function and controller.
+
+	  This will enable the configfs entry that can be used to configure
+	  the target function and used to bind the function with a target
+	  controller.
+
diff --git a/drivers/i3c/Makefile b/drivers/i3c/Makefile
index 11982efbc6d91..c275aeae8970c 100644
--- a/drivers/i3c/Makefile
+++ b/drivers/i3c/Makefile
@@ -1,4 +1,6 @@ 
 # SPDX-License-Identifier: GPL-2.0
 i3c-y				:= device.o master.o
 obj-$(CONFIG_I3C)		+= i3c.o
+obj-$(CONFIG_I3C_TARGET)                += target.o
+obj-$(CONFIG_I3C_TARGET_CONFIGFS)       += i3c-cfs.o
 obj-$(CONFIG_I3C)		+= master/
diff --git a/drivers/i3c/i3c-cfs.c b/drivers/i3c/i3c-cfs.c
new file mode 100644
index 0000000000000..a2f0f44fcdaea
--- /dev/null
+++ b/drivers/i3c/i3c-cfs.c
@@ -0,0 +1,389 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Configfs to configure the I3C Slave
+ *
+ * Copyright (C) 2023 NXP
+ * Author: Frank Li <Frank.Li@nxp.com>
+ */
+
+#include <linux/configfs.h>
+#include <linux/module.h>
+#include <linux/i3c/target.h>
+#include <linux/idr.h>
+#include <linux/slab.h>
+
+static DEFINE_MUTEX(functions_mutex);
+static struct config_group *functions_group;
+static struct config_group *controllers_group;
+
+struct i3c_target_func_group {
+	struct config_group group;
+	struct i3c_target_func *func;
+};
+
+struct i3c_target_ctrl_group {
+	struct config_group group;
+	struct i3c_target_ctrl *ctrl;
+};
+
+static inline struct i3c_target_func_group *to_i3c_target_func_group(struct config_item *item)
+{
+	return container_of(to_config_group(item), struct i3c_target_func_group, group);
+}
+
+static inline struct i3c_target_ctrl_group *to_i3c_target_ctrl_group(struct config_item *item)
+{
+	return container_of(to_config_group(item), struct i3c_target_ctrl_group, group);
+}
+
+static int i3c_target_ctrl_func_link(struct config_item *ctrl_cfg, struct config_item *func_cfg)
+{
+	struct i3c_target_func_group *func_group = to_i3c_target_func_group(func_cfg);
+	struct i3c_target_ctrl_group *ctrl_group = to_i3c_target_ctrl_group(ctrl_cfg);
+	struct i3c_target_ctrl *ctrl = ctrl_group->ctrl;
+	struct i3c_target_func *func = func_group->func;
+	int ret;
+
+	ret = i3c_target_ctrl_add_func(ctrl, func);
+	if (ret)
+		return ret;
+
+	ret = i3c_target_func_bind(func);
+	if (ret) {
+		i3c_target_ctrl_remove_func(ctrl, func);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void i3c_target_ctrl_func_unlink(struct config_item *ctrl_cfg, struct config_item *func_cfg)
+{
+	struct i3c_target_func_group *func_group = to_i3c_target_func_group(func_cfg->ci_parent);
+	struct i3c_target_ctrl_group *ctrl_group = to_i3c_target_ctrl_group(ctrl_cfg);
+	struct i3c_target_ctrl *ctrl = ctrl_group->ctrl;
+	struct i3c_target_func *func = func_group->func;
+
+	i3c_target_func_unbind(func);
+	i3c_target_ctrl_remove_func(ctrl, func);
+}
+
+static ssize_t i3c_target_ctrl_hotjoin_store(struct config_item *item, const char *page, size_t len)
+{
+	struct i3c_target_ctrl_group *ctrl_group = to_i3c_target_ctrl_group(item);
+	struct i3c_target_ctrl *ctrl;
+	int ret;
+
+	ctrl = ctrl_group->ctrl;
+
+	ret = i3c_target_ctrl_hotjoin(ctrl);
+	if (ret) {
+		dev_err(&ctrl->dev, "failed to hotjoin i3c target controller\n");
+		return -EINVAL;
+	}
+
+	return len;
+}
+
+static ssize_t i3c_target_ctrl_hotjoin_show(struct config_item *item, char *page)
+{
+	return sysfs_emit(page, "%d\n", 0);
+}
+
+CONFIGFS_ATTR(i3c_target_ctrl_, hotjoin);
+
+static struct configfs_item_operations i3c_target_ctrl_item_ops = {
+	.allow_link     = i3c_target_ctrl_func_link,
+	.drop_link      = i3c_target_ctrl_func_unlink,
+};
+
+static struct configfs_attribute *i3c_target_ctrl_attrs[] = {
+	&i3c_target_ctrl_attr_hotjoin,
+	NULL,
+};
+
+static const struct config_item_type i3c_target_ctrl_type = {
+	.ct_item_ops    = &i3c_target_ctrl_item_ops,
+	.ct_attrs	= i3c_target_ctrl_attrs,
+	.ct_owner       = THIS_MODULE,
+};
+
+/**
+ * i3c_target_cfs_add_ctrl_group() - add I3C target controller group
+ * @ctrl: I3C target controller device
+ *
+ * Return: Pointer to struct config_group
+ */
+struct config_group *i3c_target_cfs_add_ctrl_group(struct i3c_target_ctrl *ctrl)
+{
+	struct i3c_target_ctrl_group *ctrl_group;
+	struct config_group *group;
+	int ret;
+
+	ctrl_group = kzalloc(sizeof(*ctrl_group), GFP_KERNEL);
+	if (!ctrl_group) {
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	group = &ctrl_group->group;
+
+	config_group_init_type_name(group, dev_name(&ctrl->dev), &i3c_target_ctrl_type);
+	ret = configfs_register_group(controllers_group, group);
+	if (ret) {
+		pr_err("failed to register configfs group for %s\n", dev_name(&ctrl->dev));
+		goto err_register_group;
+	}
+
+	ctrl_group->ctrl = ctrl;
+
+	return group;
+
+err_register_group:
+	kfree(ctrl_group);
+
+err:
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL(i3c_target_cfs_add_ctrl_group);
+
+/**
+ * i3c_target_cfs_remove_ctrl_group() - remove I3C target controller group
+ * @group: the group to be removed
+ */
+void i3c_target_cfs_remove_ctrl_group(struct config_group *group)
+{
+	struct i3c_target_ctrl_group *ctrl_group;
+
+	if (!group)
+		return;
+
+	ctrl_group = container_of(group, struct i3c_target_ctrl_group, group);
+	i3c_target_ctrl_put(ctrl_group->ctrl);
+	configfs_unregister_group(&ctrl_group->group);
+	kfree(ctrl_group);
+}
+EXPORT_SYMBOL(i3c_target_cfs_remove_ctrl_group);
+
+#define I3C_SLAVE_ATTR_R(_name)                                                \
+static ssize_t i3c_target_func_##_name##_show(struct config_item *item, char *page)    \
+{                                                                              \
+	struct i3c_target_func *func = to_i3c_target_func_group(item)->func;                     \
+	return sysfs_emit(page, "0x%04x\n", func->_name);               \
+}
+
+#define I3C_SLAVE_ATTR_W(_name, _u)                                            \
+static ssize_t i3c_target_func_##_name##_store(struct config_item *item,               \
+				       const char *page, size_t len)           \
+{                                                                              \
+	_u val;                                                               \
+	struct i3c_target_func *func = to_i3c_target_func_group(item)->func;                     \
+	if (kstrto##_u(page, 0, &val) < 0)                                      \
+		return -EINVAL;                                                \
+	func->_name = val;                                              \
+	return len;                                                            \
+}
+
+I3C_SLAVE_ATTR_R(vendor_id);
+I3C_SLAVE_ATTR_W(vendor_id, u16);
+CONFIGFS_ATTR(i3c_target_func_, vendor_id);
+
+I3C_SLAVE_ATTR_R(vendor_info);
+I3C_SLAVE_ATTR_W(vendor_info, u16);
+CONFIGFS_ATTR(i3c_target_func_, vendor_info);
+
+I3C_SLAVE_ATTR_R(part_id);
+I3C_SLAVE_ATTR_W(part_id, u16);
+CONFIGFS_ATTR(i3c_target_func_, part_id);
+
+I3C_SLAVE_ATTR_R(instance_id);
+I3C_SLAVE_ATTR_W(instance_id, u8);
+CONFIGFS_ATTR(i3c_target_func_, instance_id);
+
+I3C_SLAVE_ATTR_R(ext_id);
+I3C_SLAVE_ATTR_W(ext_id, u16);
+CONFIGFS_ATTR(i3c_target_func_, ext_id);
+
+I3C_SLAVE_ATTR_R(max_write_len);
+I3C_SLAVE_ATTR_W(max_write_len, u16);
+CONFIGFS_ATTR(i3c_target_func_, max_write_len);
+
+I3C_SLAVE_ATTR_R(max_read_len);
+I3C_SLAVE_ATTR_W(max_read_len, u16);
+CONFIGFS_ATTR(i3c_target_func_, max_read_len);
+
+I3C_SLAVE_ATTR_R(bcr);
+I3C_SLAVE_ATTR_W(bcr, u8);
+CONFIGFS_ATTR(i3c_target_func_, bcr);
+
+I3C_SLAVE_ATTR_R(dcr);
+I3C_SLAVE_ATTR_W(dcr, u8);
+CONFIGFS_ATTR(i3c_target_func_, dcr);
+
+static struct configfs_attribute *i3c_target_func_attrs[] = {
+	&i3c_target_func_attr_vendor_id,
+	&i3c_target_func_attr_vendor_info,
+	&i3c_target_func_attr_part_id,
+	&i3c_target_func_attr_instance_id,
+	&i3c_target_func_attr_ext_id,
+	&i3c_target_func_attr_max_write_len,
+	&i3c_target_func_attr_max_read_len,
+	&i3c_target_func_attr_bcr,
+	&i3c_target_func_attr_dcr,
+	NULL,
+};
+
+static const struct config_item_type i3c_target_func_type = {
+	.ct_attrs       = i3c_target_func_attrs,
+	.ct_owner       = THIS_MODULE,
+};
+
+static struct config_group *i3c_target_func_make(struct config_group *group, const char *name)
+{
+	struct i3c_target_func_group *func_group;
+	struct i3c_target_func *func;
+	int err;
+
+	func_group = kzalloc(sizeof(*func_group), GFP_KERNEL);
+	if (!func_group)
+		return ERR_PTR(-ENOMEM);
+
+	config_group_init_type_name(&func_group->group, name, &i3c_target_func_type);
+
+	func = i3c_target_func_create(group->cg_item.ci_name, name);
+	if (IS_ERR(func)) {
+		pr_err("failed to create i3c target function device\n");
+		err = -EINVAL;
+		goto free_group;
+	}
+
+	func->group = &func_group->group;
+
+	func_group->func = func;
+
+	return &func_group->group;
+
+free_group:
+	kfree(func_group);
+
+	return ERR_PTR(err);
+}
+
+static void i3c_target_func_drop(struct config_group *group, struct config_item *item)
+{
+	config_item_put(item);
+}
+
+static struct configfs_group_operations i3c_target_func_group_ops = {
+	.make_group     = &i3c_target_func_make,
+	.drop_item      = &i3c_target_func_drop,
+};
+
+static const struct config_item_type i3c_target_func_group_type = {
+	.ct_group_ops   = &i3c_target_func_group_ops,
+	.ct_owner       = THIS_MODULE,
+};
+
+/**
+ * i3c_target_cfs_add_func_group() - add I3C target function group
+ * @name: group name
+ *
+ * Return: Pointer to struct config_group
+ */
+struct config_group *i3c_target_cfs_add_func_group(const char *name)
+{
+	struct config_group *group;
+
+	group = configfs_register_default_group(functions_group, name,
+						&i3c_target_func_group_type);
+	if (IS_ERR(group))
+		pr_err("failed to register configfs group for %s function\n",
+		       name);
+
+	return group;
+}
+EXPORT_SYMBOL(i3c_target_cfs_add_func_group);
+
+/**
+ * i3c_target_cfs_remove_func_group() - add I3C target function group
+ * @group: group to be removed
+ */
+void i3c_target_cfs_remove_func_group(struct config_group *group)
+{
+	if (IS_ERR_OR_NULL(group))
+		return;
+
+	configfs_unregister_default_group(group);
+}
+EXPORT_SYMBOL(i3c_target_cfs_remove_func_group);
+
+static const struct config_item_type i3c_target_controllers_type = {
+	.ct_owner       = THIS_MODULE,
+};
+
+static const struct config_item_type i3c_target_functions_type = {
+	.ct_owner       = THIS_MODULE,
+};
+
+static const struct config_item_type i3c_target_type = {
+	.ct_owner       = THIS_MODULE,
+};
+
+static struct configfs_subsystem i3c_target_cfs_subsys = {
+	.su_group = {
+		.cg_item = {
+			.ci_namebuf = "i3c_target",
+			.ci_type = &i3c_target_type,
+		},
+	},
+	.su_mutex = __MUTEX_INITIALIZER(i3c_target_cfs_subsys.su_mutex),
+};
+
+static int __init i3c_target_cfs_init(void)
+{
+	int ret;
+	struct config_group *root = &i3c_target_cfs_subsys.su_group;
+
+	config_group_init(root);
+
+	ret = configfs_register_subsystem(&i3c_target_cfs_subsys);
+	if (ret) {
+		pr_err("Error %d while registering subsystem %s\n",
+		       ret, root->cg_item.ci_namebuf);
+		goto err;
+	}
+
+	functions_group = configfs_register_default_group(root, "functions",
+							  &i3c_target_functions_type);
+	if (IS_ERR(functions_group)) {
+		ret = PTR_ERR(functions_group);
+		pr_err("Error %d while registering functions group\n",
+		       ret);
+		goto err_functions_group;
+	}
+
+	controllers_group =
+		configfs_register_default_group(root, "controllers",
+						&i3c_target_controllers_type);
+	if (IS_ERR(controllers_group)) {
+		ret = PTR_ERR(controllers_group);
+		pr_err("Error %d while registering controllers group\n",
+		       ret);
+		goto err_controllers_group;
+	}
+
+	return 0;
+
+err_controllers_group:
+	configfs_unregister_default_group(functions_group);
+
+err_functions_group:
+	configfs_unregister_subsystem(&i3c_target_cfs_subsys);
+
+err:
+	return ret;
+}
+module_init(i3c_target_cfs_init);
+
+MODULE_DESCRIPTION("I3C FUNC CONFIGFS");
+MODULE_AUTHOR("Frank Li <Frank.Li@nxp.com>");
diff --git a/drivers/i3c/target.c b/drivers/i3c/target.c
new file mode 100644
index 0000000000000..f0bcda2c4599f
--- /dev/null
+++ b/drivers/i3c/target.c
@@ -0,0 +1,453 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * configfs to configure the I3C Slave
+ *
+ * Copyright (C) 2023 NXP
+ * Author: Frank Li <Frank.Li@nxp.com>
+ */
+
+#include <linux/configfs.h>
+#include <linux/module.h>
+#include <linux/i3c/target.h>
+#include <linux/idr.h>
+#include <linux/slab.h>
+
+static DEFINE_MUTEX(func_lock);
+static struct class *i3c_target_ctrl_class;
+
+static void i3c_target_func_dev_release(struct device *dev)
+{
+	struct i3c_target_func *func = to_i3c_target_func(dev);
+
+	kfree(func->name);
+	kfree(func);
+}
+
+static const struct device_type i3c_target_func_type = {
+	.release        = i3c_target_func_dev_release,
+};
+
+static int i3c_target_func_match_driver(struct device *dev, struct device_driver *drv)
+{
+	return !strncmp(dev_name(dev), drv->name, strlen(drv->name));
+}
+
+static int i3c_target_func_device_probe(struct device *dev)
+{
+	struct i3c_target_func *func = to_i3c_target_func(dev);
+	struct i3c_target_func_driver *driver = to_i3c_target_func_driver(dev->driver);
+
+	if (!driver->probe)
+		return -ENODEV;
+
+	func->driver = driver;
+
+	return driver->probe(func);
+}
+
+static void i3c_target_func_device_remove(struct device *dev)
+{
+	struct i3c_target_func *func = to_i3c_target_func(dev);
+	struct i3c_target_func_driver *driver = to_i3c_target_func_driver(dev->driver);
+
+	if (driver->remove)
+		driver->remove(func);
+	func->driver = NULL;
+}
+
+static const struct bus_type i3c_target_func_bus_type = {
+	.name = "i3c_target_func",
+	.probe = i3c_target_func_device_probe,
+	.remove = i3c_target_func_device_remove,
+	.match = i3c_target_func_match_driver,
+};
+
+static void i3c_target_ctrl_release(struct device *dev)
+{
+	kfree(to_i3c_target_ctrl(dev));
+}
+
+static void devm_i3c_target_ctrl_release(struct device *dev, void *res)
+{
+	struct i3c_target_ctrl *ctrl = *(struct i3c_target_ctrl **)res;
+
+	i3c_target_ctrl_destroy(ctrl);
+}
+
+struct i3c_target_ctrl *
+__devm_i3c_target_ctrl_create(struct device *dev, const struct i3c_target_ctrl_ops *ops,
+			     struct module *owner)
+{
+	struct i3c_target_ctrl **ptr, *ctrl;
+
+	ptr = devres_alloc(devm_i3c_target_ctrl_release, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return ERR_PTR(-ENOMEM);
+
+	ctrl = __i3c_target_ctrl_create(dev, ops, owner);
+	if (!IS_ERR(ctrl)) {
+		*ptr = ctrl;
+		devres_add(dev, ptr);
+	} else {
+		devres_free(ptr);
+	}
+
+	return ctrl;
+}
+
+static int devm_i3c_target_ctrl_match(struct device *dev, void *res, void *match_data)
+{
+	struct i3c_target_ctrl **ptr = res;
+
+	return *ptr == match_data;
+}
+
+/**
+ * __i3c_target_ctrl_create() - create a new target controller device
+ * @dev: device that is creating the new target controller
+ * @ops: function pointers for performing target controller  operations
+ * @owner: the owner of the module that creates the target controller device
+ *
+ * Return: Pointer to struct i3c_target_ctrl
+ */
+struct i3c_target_ctrl *
+__i3c_target_ctrl_create(struct device *dev, const struct i3c_target_ctrl_ops *ops,
+			struct module *owner)
+{
+	struct i3c_target_ctrl *ctrl;
+	int ret;
+
+	if (WARN_ON(!dev))
+		return ERR_PTR(-EINVAL);
+
+	ctrl = kzalloc(sizeof(*ctrl), GFP_KERNEL);
+	if (!ctrl)
+		return ERR_PTR(-ENOMEM);
+
+	device_initialize(&ctrl->dev);
+	ctrl->dev.class = i3c_target_ctrl_class;
+	ctrl->dev.parent = dev;
+	ctrl->dev.release = i3c_target_ctrl_release;
+	ctrl->ops = ops;
+
+	ret = dev_set_name(&ctrl->dev, "%s", dev_name(dev));
+	if (ret)
+		goto put_dev;
+
+	ret = device_add(&ctrl->dev);
+	if (ret)
+		goto put_dev;
+
+	ctrl->group = i3c_target_cfs_add_ctrl_group(ctrl);
+	if (!ctrl->group)
+		goto put_dev;
+
+	return ctrl;
+
+put_dev:
+	put_device(&ctrl->dev);
+	kfree(ctrl);
+
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(__i3c_target_ctrl_create);
+
+/**
+ * devm_i3c_target_ctrl_destroy() - destroy the target controller device
+ * @dev: device that hat has to be destroy
+ * @ctrl: the target controller device that has to be destroy
+ *
+ * Invoke to create a new target controller device and add it to i3c_target class. While at that, it
+ * also associates the device with the i3c_target using devres. On driver detach, release function
+ * is invoked on the devres data, then devres data is freed.
+ */
+void devm_i3c_target_ctrl_destroy(struct device *dev, struct i3c_target_ctrl *ctrl)
+{
+	int r;
+
+	r = devres_destroy(dev, devm_i3c_target_ctrl_release, devm_i3c_target_ctrl_match,
+			   ctrl);
+	dev_WARN_ONCE(dev, r, "couldn't find I3C controller resource\n");
+}
+EXPORT_SYMBOL_GPL(devm_i3c_target_ctrl_destroy);
+
+/**
+ * i3c_target_ctrl_destroy() - destroy the target controller device
+ * @ctrl: the target controller device that has to be destroyed
+ *
+ * Invoke to destroy the I3C target device
+ */
+void i3c_target_ctrl_destroy(struct i3c_target_ctrl *ctrl)
+{
+	i3c_target_cfs_remove_ctrl_group(ctrl->group);
+	device_unregister(&ctrl->dev);
+}
+EXPORT_SYMBOL_GPL(i3c_target_ctrl_destroy);
+
+/**
+ * i3c_target_ctrl_add_func() - bind I3C target function to an target controller
+ * @ctrl: the controller device to which the target function should be added
+ * @func: the target function to be added
+ *
+ * An I3C target device can have only one functions.
+ */
+int i3c_target_ctrl_add_func(struct i3c_target_ctrl *ctrl, struct i3c_target_func *func)
+{
+	if (ctrl->func)
+		return -EBUSY;
+
+	ctrl->func = func;
+	func->ctrl = ctrl;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(i3c_target_ctrl_add_func);
+
+/**
+ * i3c_target_ctrl_remove_func() - unbind I3C target function to an target controller
+ * @ctrl: the controller device to which the target function should be removed
+ * @func: the target function to be removed
+ *
+ * An I3C target device can have only one functions.
+ */
+void i3c_target_ctrl_remove_func(struct i3c_target_ctrl *ctrl, struct i3c_target_func *func)
+{
+	ctrl->func = NULL;
+}
+EXPORT_SYMBOL_GPL(i3c_target_ctrl_remove_func);
+
+/**
+ * i3c_target_ctrl_get() - get the I3C target controller
+ * @name: device name of the target controller
+ *
+ * Invoke to get struct i3c_target_ctrl * corresponding to the device name of the
+ * target controller
+ */
+struct i3c_target_ctrl *i3c_target_ctrl_get(const char *name)
+{
+	int ret = -EINVAL;
+	struct i3c_target_ctrl *ctrl;
+	struct device *dev;
+	struct class_dev_iter iter;
+
+	class_dev_iter_init(&iter, i3c_target_ctrl_class, NULL, NULL);
+	while ((dev = class_dev_iter_next(&iter))) {
+		if (strcmp(name, dev_name(dev)))
+			continue;
+
+		ctrl = to_i3c_target_ctrl(dev);
+		if (!try_module_get(ctrl->ops->owner)) {
+			ret = -EINVAL;
+			goto err;
+		}
+
+		class_dev_iter_exit(&iter);
+		get_device(&ctrl->dev);
+		return ctrl;
+	}
+
+err:
+	class_dev_iter_exit(&iter);
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(i3c_target_ctrl_get);
+
+/**
+ * i3c_target_ctrl_put() - release the I3C endpoint controller
+ * @ctrl: target controller returned by pci_target_get()
+ *
+ * release the refcount the caller obtained by invoking i3c_target_ctrl_get()
+ */
+void i3c_target_ctrl_put(struct i3c_target_ctrl *ctrl)
+{
+	if (!ctrl || IS_ERR(ctrl))
+		return;
+
+	module_put(ctrl->ops->owner);
+	put_device(&ctrl->dev);
+}
+EXPORT_SYMBOL_GPL(i3c_target_ctrl_put);
+
+/**
+ * i3c_target_ctrl_hotjoin() - trigger device hotjoin
+ * @ctrl:  target controller
+ *
+ * return: 0: success, others failure
+ */
+int i3c_target_ctrl_hotjoin(struct i3c_target_ctrl *ctrl)
+{
+	if (!ctrl || IS_ERR(ctrl))
+		return -EINVAL;
+
+	if (!ctrl->ops->hotjoin)
+		return -EINVAL;
+
+	return ctrl->ops->hotjoin(ctrl);
+}
+EXPORT_SYMBOL_GPL(i3c_target_ctrl_hotjoin);
+
+/**
+ * i3c_target_func_bind() - Notify the function driver that the function device has been bound to a
+ *			   controller device
+ * @func: the function device which has been bound to the controller device
+ *
+ * Invoke to notify the function driver that it has been bound to a controller device
+ */
+int i3c_target_func_bind(struct i3c_target_func *func)
+{
+	struct device *dev = &func->dev;
+	int ret;
+
+	if (!func->driver) {
+		dev_WARN(dev, "func device not bound to driver\n");
+		return -EINVAL;
+	}
+
+	if (!try_module_get(func->driver->owner))
+		return -EAGAIN;
+
+	mutex_lock(&func->lock);
+	ret = func->driver->ops->bind(func);
+	if (!ret)
+		func->is_bound = true;
+	mutex_unlock(&func->lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(i3c_target_func_bind);
+
+/**
+ * i3c_target_func_unbind() - Notify the function driver that the binding between the function
+ *			      device and controller device has been lost.
+ * @func: the function device which has lost the binding with the controller device.
+ *
+ * Invoke to notify the function driver that the binding between the function device and controller
+ * device has been lost.
+ */
+void i3c_target_func_unbind(struct i3c_target_func *func)
+{
+	if (!func->driver) {
+		dev_WARN(&func->dev, "func device not bound to driver\n");
+		return;
+	}
+
+	mutex_lock(&func->lock);
+	if (func->is_bound)
+		func->driver->ops->unbind(func);
+	mutex_unlock(&func->lock);
+
+	module_put(func->driver->owner);
+}
+EXPORT_SYMBOL_GPL(i3c_target_func_unbind);
+
+/**
+ * i3c_target_func_create() - create a new I3C function device
+ * @drv_name: the driver name of the I3C function device.
+ * @name: the name of the function device.
+ *
+ * Invoke to create a new I3C function device by providing the name of the function device.
+ */
+struct i3c_target_func *i3c_target_func_create(const char *drv_name, const char *name)
+{
+	struct i3c_target_func *func;
+	struct device *dev;
+	int ret;
+
+	func = kzalloc(sizeof(*func), GFP_KERNEL);
+	if (!func)
+		return ERR_PTR(-ENOMEM);
+
+	dev = &func->dev;
+	device_initialize(dev);
+	dev->bus = &i3c_target_func_bus_type;
+	dev->type = &i3c_target_func_type;
+	mutex_init(&func->lock);
+
+	ret = dev_set_name(dev, "%s.%s", drv_name, name);
+	if (ret) {
+		put_device(dev);
+		return ERR_PTR(ret);
+	}
+
+	ret = device_add(dev);
+	if (ret) {
+		put_device(dev);
+		return ERR_PTR(ret);
+	}
+
+	return func;
+}
+EXPORT_SYMBOL_GPL(i3c_target_func_create);
+
+/**
+ * __i3c_target_func_register_driver() - register a new I3C function driver
+ * @driver: structure representing I3C function driver
+ * @owner: the owner of the module that registers the I3C function driver
+ *
+ * Invoke to register a new I3C function driver.
+ */
+int __i3c_target_func_register_driver(struct i3c_target_func_driver *driver, struct module *owner)
+{
+	int ret = -EEXIST;
+
+	if (!driver->ops)
+		return -EINVAL;
+
+	if (!driver->ops->bind || !driver->ops->unbind)
+		return -EINVAL;
+
+	driver->driver.bus = &i3c_target_func_bus_type;
+	driver->driver.owner = owner;
+
+	ret = driver_register(&driver->driver);
+	if (ret)
+		return ret;
+
+	i3c_target_cfs_add_func_group(driver->driver.name);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(__i3c_target_func_register_driver);
+
+/**
+ * i3c_target_func_unregister_driver() - unregister the I3C function driver
+ * @fd: the I3C function driver that has to be unregistered
+ *
+ * Invoke to unregister the I3C function driver.
+ */
+void i3c_target_func_unregister_driver(struct i3c_target_func_driver *fd)
+{
+	mutex_lock(&func_lock);
+	mutex_unlock(&func_lock);
+}
+EXPORT_SYMBOL_GPL(i3c_target_func_unregister_driver);
+
+static int __init i3c_target_init(void)
+{
+	int ret;
+
+	i3c_target_ctrl_class = class_create("i3c_target");
+	if (IS_ERR(i3c_target_ctrl_class)) {
+		pr_err("failed to create i3c target class --> %ld\n",
+		       PTR_ERR(i3c_target_ctrl_class));
+		return PTR_ERR(i3c_target_ctrl_class);
+	}
+
+	ret = bus_register(&i3c_target_func_bus_type);
+	if (ret) {
+		class_destroy(i3c_target_ctrl_class);
+		pr_err("failed to register i3c target func bus --> %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+module_init(i3c_target_init);
+
+static void __exit i3c_target_exit(void)
+{
+	class_destroy(i3c_target_ctrl_class);
+	bus_unregister(&i3c_target_func_bus_type);
+}
+module_exit(i3c_target_exit);
+
diff --git a/include/linux/i3c/target.h b/include/linux/i3c/target.h
new file mode 100644
index 0000000000000..9b73114588350
--- /dev/null
+++ b/include/linux/i3c/target.h
@@ -0,0 +1,527 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright 2023 NXP.
+ *
+ * Author: Frank Li <Frank.Li@nxp.com>
+ */
+
+#ifndef I3C_TARGET_H
+#define I3C_TARGET_H
+
+#include <linux/device.h>
+
+struct i3c_target_func;
+struct i3c_target_ctrl;
+
+/**
+ * struct i3c_target_func_ops - set of function pointers for performing i3c target function
+ *				operations
+ * @bind: ops to perform when a controller device has been bound to function device
+ * @unbind: ops to perform when a binding has been lost between a controller device and function
+ *	    device
+ */
+struct i3c_target_func_ops {
+	int (*bind)(struct i3c_target_func *func);
+	void (*unbind)(struct i3c_target_func *func);
+};
+
+/**
+ * struct i3c_target_func_driver - represents the I3C function driver
+ * @probe: ops to perform when a new function device has been bound to the function driver
+ * @remove: ops to perform when the binding between the function device and function driver is
+ *	    broken
+ * @name: I3C Function driver name
+ * @driver: I3C Function driver
+ * @ops: set of function pointers for performing function operations
+ * @owner: the owner of the module that registers the I3C function driver
+ * @epf_group: list of configfs group corresponding to the I3C function driver
+ */
+struct i3c_target_func_driver {
+	int (*probe)(struct i3c_target_func *func);
+	void (*remove)(struct i3c_target_func *func);
+
+	char *name;
+	struct device_driver driver;
+	struct i3c_target_func_ops *ops;
+	struct module *owner;
+};
+
+/**
+ * struct i3c_target_func - represents the I3C function device
+ * @dev: the I3C function device
+ * @name: the name of the I3C function device
+ * @driver: the function driver to which this function device is bound
+ * @group: configfs group associated with the EPF device
+ * @lock: mutex to protect i3c_target_func_ops
+ * @ctrl: binded I3C controller device
+ * @is_bound: indicates if bind notification to function driver has been invoked
+ * @vendor_id: vendor id
+ * @part_id: part id
+ * @instance_id: instance id
+ * @ext_id: ext id
+ * @vendor_info: vendor info
+ * @static_addr: static address for I2C. It is 0 for I3C.
+ * @max_write_len: maximum write length
+ * @max_read_len: maximum read length
+ * @bcr: bus characteristics register (BCR)
+ * @dcr: device characteristics register (DCR)
+ */
+struct i3c_target_func {
+	struct device dev;
+	char *name;
+	struct i3c_target_func_driver *driver;
+	struct config_group *group;
+	/* mutex to protect against concurrent access of i3c_target_func_ops */
+	struct mutex lock;
+	struct i3c_target_ctrl *ctrl;
+	bool is_bound;
+
+	u16 vendor_id;
+	u16 part_id;
+	u8 instance_id;
+	u16 ext_id;
+	u8 vendor_info;
+	u16 static_addr;
+	u16 max_write_len;	//0 is hardware default max value
+	u16 max_read_len;	//0 is hardware default max value
+	u8 bcr;
+	u8 dcr;
+};
+
+enum i3c_request_stat {
+	I3C_REQUEST_OKAY,
+	I3C_REQUEST_PARTIAL,
+	I3C_REQUEST_ERR,
+	I3C_REQUEST_CANCEL,
+};
+
+/**
+ * struct i3c_request - represents the an I3C transfer request
+ * @buf: data buffer
+ * @length: data length
+ * @complete: call back function when request finished or cancelled
+ * @context: general data for complete callback function
+ * @list: link list
+ * @status: transfer status
+ * @actual: how much actually transferred
+ * @ctrl: I3C target controller associate with this request
+ * @tx: transfer direction, 1: target to master, 0: master to target
+ */
+struct i3c_request {
+	void *buf;
+	unsigned int length;
+
+	void (*complete)(struct i3c_request *req);
+	void *context;
+	struct list_head list;
+
+	enum i3c_request_stat status;
+	unsigned int actual;
+	struct i3c_target_ctrl *ctrl;
+	bool tx;
+};
+
+/**
+ * struct i3c_target_ctrl_features - represents I3C target controller features.
+ * @tx_fifo_sz: tx hardware fifo size
+ * @rx_fifo_sz: rx hardware fifo size
+ */
+struct i3c_target_ctrl_features {
+	u32 tx_fifo_sz;
+	u32 rx_fifo_sz;
+};
+
+/**
+ * struct i3c_target_ctrl_ops - set of function pointers for performing controller operations
+ * @set_config: set I3C controller configuration
+ * @enable: enable I3C controller
+ * @disable: disable I3C controller
+ * @raise_ibi: raise IBI interrupt to master
+ * @alloc_request: allocate a i3c_request, optional, default use kmalloc
+ * @free_request: free a i3c_request, default use kfree
+ * @queue: queue an I3C transfer
+ * @dequeue: dequeue an I3C transfer
+ * @cancel_all_reqs: call all pending requests
+ * @fifo_status: current FIFO status
+ * @fifo_flush: flush hardware FIFO
+ * @hotjoin: raise hotjoin request to master
+ * @set_status_format1: set i3c status format1
+ * @get_status_format1: get i3c status format1
+ * @get_addr: get i3c dynmatic address
+ * @get_features: ops to get the features supported by the I3C target controller
+ * @owner: the module owner containing the ops
+ */
+struct i3c_target_ctrl_ops {
+	int (*set_config)(struct i3c_target_ctrl *ctrl, struct i3c_target_func *func);
+	int (*enable)(struct i3c_target_ctrl *ctrl);
+	int (*disable)(struct i3c_target_ctrl *ctrl);
+	int (*raise_ibi)(struct i3c_target_ctrl *ctrl, void *p, u8 size);
+
+	struct i3c_request *(*alloc_request)(struct i3c_target_ctrl *ctrl, gfp_t gfp_flags);
+	void (*free_request)(struct i3c_request *req);
+
+	int (*queue)(struct i3c_request *req, gfp_t gfp_flags);
+	int (*dequeue)(struct i3c_request *req);
+
+	void (*cancel_all_reqs)(struct i3c_target_ctrl *ctrl, bool tx);
+
+	int (*fifo_status)(struct i3c_target_ctrl *ctrl, bool tx);
+	void (*fifo_flush)(struct i3c_target_ctrl *ctrl, bool tx);
+	int (*hotjoin)(struct i3c_target_ctrl *ctrl);
+	int (*set_status_format1)(struct i3c_target_ctrl *ctrl, u16 status);
+	u16 (*get_status_format1)(struct i3c_target_ctrl *ctrl);
+	u8  (*get_addr)(struct i3c_target_ctrl *ctrl);
+	const struct i3c_target_ctrl_features *(*get_features)(struct i3c_target_ctrl *ctrl);
+	struct module *owner;
+};
+
+/**
+ * struct i3c_target_ctrl - represents the I3C target device
+ * @dev: I3C target device
+ * @ops: function pointers for performing endpoint operations
+ * @func: target functions present in this controller device
+ * @group: configfs group representing the I3C controller device
+ */
+struct i3c_target_ctrl {
+	struct device dev;
+	const struct i3c_target_ctrl_ops *ops;
+	struct i3c_target_func *func;
+	struct config_group *group;
+};
+
+/**
+ * i3c_target_ctrl_raise_ibi() - Raise IBI to master
+ * @ctrl: I3C target controller
+ * @p: optional data for IBI
+ * @size: size of optional data
+ *
+ * Returns: Zero for success, or an error code in case of failure
+ */
+static inline int i3c_target_ctrl_raise_ibi(struct i3c_target_ctrl *ctrl, void *p, u8 size)
+{
+	if (ctrl && ctrl->ops && ctrl->ops->raise_ibi)
+		return ctrl->ops->raise_ibi(ctrl, p, size);
+
+	return -EINVAL;
+}
+
+/**
+ * i3c_target_ctrl_cancel_all_reqs() - Cancel all pending request
+ * @ctrl: I3C target controller
+ * @tx: Transfer diretion queue
+ */
+static inline void i3c_target_ctrl_cancel_all_reqs(struct i3c_target_ctrl *ctrl, bool tx)
+{
+	if (ctrl && ctrl->ops && ctrl->ops->cancel_all_reqs)
+		ctrl->ops->cancel_all_reqs(ctrl, tx);
+}
+
+/**
+ * i3c_target_ctrl_set_config() - Set controller configuration
+ * @ctrl: I3C target controller device
+ * @func: Function device
+ *
+ * Returns: Zero for success, or an error code in case of failure
+ */
+static inline int
+i3c_target_ctrl_set_config(struct i3c_target_ctrl *ctrl, struct i3c_target_func *func)
+{
+	if (ctrl && ctrl->ops && ctrl->ops->set_config)
+		return ctrl->ops->set_config(ctrl, func);
+
+	return -EINVAL;
+}
+
+/**
+ * i3c_target_ctrl_enable() - Enable I3C controller
+ * @ctrl: I3C target controller device
+ *
+ * Returns: Zero for success, or an error code in case of failure
+ */
+static inline int
+i3c_target_ctrl_enable(struct i3c_target_ctrl *ctrl)
+{
+	if (ctrl && ctrl->ops && ctrl->ops->enable)
+		return ctrl->ops->enable(ctrl);
+
+	return -EINVAL;
+}
+
+/**
+ * i3c_target_ctrl_disable() - Disable I3C controller
+ * @ctrl: I3C target controller device
+ *
+ * Returns: Zero for success, or an error code in case of failure
+ */
+static inline int
+i3c_target_ctrl_disable(struct i3c_target_ctrl *ctrl)
+{
+	if (ctrl && ctrl->ops && ctrl->ops->disable)
+		return ctrl->ops->disable(ctrl);
+
+	return -EINVAL;
+}
+
+/**
+ * i3c_target_ctrl_alloc_request() - Alloc an I3C transfer
+ * @ctrl: I3C target controller device
+ * @gfp_flags: additional gfp flags used when allocating the buffers
+ *
+ * Returns: Zero for success, or an error code in case of failure
+ */
+static inline struct i3c_request *
+i3c_target_ctrl_alloc_request(struct i3c_target_ctrl *ctrl, gfp_t gfp_flags)
+{
+	struct i3c_request *req = NULL;
+
+	if (ctrl && ctrl->ops && ctrl->ops->alloc_request)
+		req = ctrl->ops->alloc_request(ctrl, gfp_flags);
+	else
+		req = kzalloc(sizeof(*req), gfp_flags);
+
+	if (req)
+		req->ctrl = ctrl;
+
+	return req;
+}
+
+/**
+ * i3c_target_ctrl_free_request() - Free an I3C transfer
+ * @req: I3C transfer request
+ *
+ * Returns: Zero for success, or an error code in case of failure
+ */
+static inline void
+i3c_target_ctrl_free_request(struct i3c_request *req)
+{
+	struct i3c_target_ctrl *ctrl;
+
+	if (!req)
+		return;
+
+	ctrl = req->ctrl;
+	if (ctrl && ctrl->ops && ctrl->ops->free_request)
+		ctrl->ops->free_request(req);
+	else
+		kfree(req);
+}
+
+/**
+ * i3c_target_ctrl_queue() - Queue an I3C transfer
+ * @req: I3C transfer request
+ * @gfp_flags: additional gfp flags used when allocating the buffers
+ *
+ * Returns: Zero for success, or an error code in case of failure
+ */
+static inline int
+i3c_target_ctrl_queue(struct i3c_request *req, gfp_t gfp_flags)
+{
+	struct i3c_target_ctrl *ctrl;
+	int ret = -EINVAL;
+
+	if (!req)
+		return -EINVAL;
+
+	ctrl = req->ctrl;
+
+	req->actual = 0;
+	req->status = 0;
+	if (ctrl && ctrl->ops && ctrl->ops->queue)
+		ret = ctrl->ops->queue(req, gfp_flags);
+
+	return ret;
+}
+
+/**
+ * i3c_target_ctrl_dequeue() - Dequeue an I3C transfer
+ * @req: I3C transfer request
+ *
+ * Returns: Zero for success, or an error code in case of failure
+ */
+static inline int
+i3c_target_ctrl_dequeue(struct i3c_request *req)
+{
+	struct i3c_target_ctrl *ctrl;
+	int ret = -EINVAL;
+
+	if (!req)
+		return -EINVAL;
+
+	ctrl = req->ctrl;
+	if (ctrl && ctrl->ops && ctrl->ops->dequeue)
+		ret = ctrl->ops->dequeue(req);
+
+	return ret;
+}
+
+/**
+ * i3c_target_ctrl_fifo_status() - Get controller FIFO status
+ * @ctrl: I3C target controller device
+ * @tx: 1: Target to master, 0: master to target
+ *
+ * Returns: How much data in FIFO
+ */
+static inline int
+i3c_target_ctrl_fifo_status(struct i3c_target_ctrl *ctrl, bool tx)
+{
+	if (ctrl && ctrl->ops && ctrl->ops->fifo_status)
+		return ctrl->ops->fifo_status(ctrl, tx);
+
+	return 0;
+}
+
+/**
+ * i3c_target_ctrl_fifo_flush() - Flush controller FIFO
+ * @ctrl: I3C target controller device
+ * @tx: 1: Target to master, 0: master to target
+ *
+ */
+static inline void
+i3c_target_ctrl_fifo_flush(struct i3c_target_ctrl *ctrl, bool tx)
+{
+	if (ctrl && ctrl->ops && ctrl->ops->fifo_flush)
+		return ctrl->ops->fifo_flush(ctrl, tx);
+}
+
+/**
+ * i3c_target_ctrl_get_features() - Get controller supported features
+ * @ctrl: I3C target controller device
+ *
+ * Returns: The pointer to struct i3c_target_ctrl_features
+ */
+static inline const struct i3c_target_ctrl_features*
+i3c_target_ctrl_get_features(struct i3c_target_ctrl *ctrl)
+{
+	if (ctrl && ctrl->ops && ctrl->ops->get_features)
+		return ctrl->ops->get_features(ctrl);
+
+	return NULL;
+}
+
+/**
+ * i3c_target_ctrl_set_status_format1() - Set controller supported features
+ * @ctrl: I3C target controller device
+ * @status: I3C GETSTATUS format1
+ *
+ * Returns: Zero for success, or an error code in case of failure
+ */
+static inline int
+i3c_target_ctrl_set_status_format1(struct i3c_target_ctrl *ctrl, u16 status)
+{
+	if (ctrl && ctrl->ops && ctrl->ops->set_status_format1)
+		return ctrl->ops->set_status_format1(ctrl, status);
+
+	return -EINVAL;
+}
+
+/**
+ * i3c_target_ctrl_get_status_format1() - Get controller supported features
+ * @ctrl: I3C target controller device
+ *
+ * Return: I3C GETSTATUS format1
+ */
+static inline u16
+i3c_target_ctrl_get_status_format1(struct i3c_target_ctrl *ctrl)
+{
+	if (ctrl && ctrl->ops && ctrl->ops->get_status_format1)
+		return ctrl->ops->get_status_format1(ctrl);
+
+	return 0;
+}
+
+/**
+ * i3c_target_ctrl_get_addr() - Get controller address
+ * @ctrl: I3C target controller device
+ *
+ * Return: address
+ */
+static inline u8 i3c_target_ctrl_get_addr(struct i3c_target_ctrl *ctrl)
+{
+	if (ctrl && ctrl->ops && ctrl->ops->get_addr)
+		return ctrl->ops->get_addr(ctrl);
+
+	return 0;
+}
+
+#define to_i3c_target_ctrl(device) container_of((device), struct i3c_target_ctrl, dev)
+
+#define to_i3c_target_func(func_dev) container_of((func_dev), struct i3c_target_func, dev)
+#define to_i3c_target_func_driver(drv) (container_of((drv), struct i3c_target_func_driver, driver))
+
+#define i3c_target_ctrl_create(dev, ops) \
+		__i3c_target_ctrl_create((dev), (ops), THIS_MODULE)
+#define devm_i3c_target_ctrl_create(dev, ops) \
+		__devm_i3c_target_ctrl_create((dev), (ops), THIS_MODULE)
+
+#ifdef CONFIG_I3C_TARGET
+struct i3c_target_ctrl *
+__devm_i3c_target_ctrl_create(struct device *dev, const struct i3c_target_ctrl_ops *ops,
+			     struct module *owner);
+struct i3c_target_ctrl *
+__i3c_target_ctrl_create(struct device *dev, const struct i3c_target_ctrl_ops *ops,
+			struct module *owner);
+
+void devm_i3c_target_ctrl_destroy(struct device *dev, struct i3c_target_ctrl *epc);
+void i3c_target_ctrl_destroy(struct i3c_target_ctrl *epc);
+
+int i3c_target_ctrl_add_func(struct i3c_target_ctrl *ctrl, struct i3c_target_func *func);
+void i3c_target_ctrl_remove_func(struct i3c_target_ctrl *ctrl, struct i3c_target_func *func);
+int i3c_target_ctrl_hotjoin(struct i3c_target_ctrl *ctrl);
+
+struct config_group *i3c_target_cfs_add_ctrl_group(struct i3c_target_ctrl *ctrl);
+
+void i3c_target_cfs_remove_ctrl_group(struct config_group *group);
+struct config_group *i3c_target_cfs_add_func_group(const char *name);
+void i3c_target_cfs_remove_func_group(struct config_group *group);
+struct i3c_target_ctrl *i3c_target_ctrl_get(const char *name);
+void i3c_target_ctrl_put(struct i3c_target_ctrl *ctrl);
+
+int i3c_target_func_bind(struct i3c_target_func *func);
+void i3c_target_func_unbind(struct i3c_target_func *func);
+struct i3c_target_func *i3c_target_func_create(const char *drv_name, const char *name);
+
+#define i3c_target_func_register_driver(drv) \
+	__i3c_target_func_register_driver(drv, THIS_MODULE)
+
+int __i3c_target_func_register_driver(struct i3c_target_func_driver *drv, struct module *owner);
+void i3c_target_func_unregister_driver(struct i3c_target_func_driver *drv);
+#else
+static inline struct i3c_target_ctrl *
+__devm_i3c_target_ctrl_create(struct device *dev, const struct i3c_target_ctrl_ops *ops,
+			     struct module *owner)
+{
+	return NULL;
+}
+
+static inline struct i3c_target_ctrl *
+__i3c_target_ctrl_create(struct device *dev, const struct i3c_target_ctrl_ops *ops,
+			struct module *owner)
+{
+	return NULL;
+}
+#endif
+
+#define DECLARE_I3C_TARGET_FUNC(_name, _probe, _remove, _ops)			\
+	static struct i3c_target_func_driver _name ## i3c_func = {		\
+		.driver.name = __stringify(_name),				\
+		.owner  = THIS_MODULE,						\
+		.probe = _probe,						\
+		.remove = _remove,						\
+		.ops = _ops							\
+	};									\
+	MODULE_ALIAS("i3cfunc:" __stringify(_name))
+
+#define DECLARE_I3C_TARGET_INIT(_name, _probe, _remove, _ops)			\
+	DECLARE_I3C_TARGET_FUNC(_name, _probe, _remove, _ops);			\
+	static int __init _name ## mod_init(void)				\
+	{									\
+		return i3c_target_func_register_driver(&_name ## i3c_func);	\
+	}									\
+	static void __exit _name ## mod_exit(void)				\
+	{									\
+		i3c_target_func_unregister_driver(&_name ## i3c_func);		\
+	}									\
+	module_init(_name ## mod_init);						\
+	module_exit(_name ## mod_exit)
+
+#endif