xref: /linux/drivers/input/serio/serio.c (revision 3e51108c72e8adbcf3180ed40527a2a9d2d0123b)

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  The Serio abstraction module
 *
 *  Copyright (c) 1999-2004 Vojtech Pavlik
 *  Copyright (c) 2004 Dmitry Torokhov
 *  Copyright (c) 2003 Daniele Bellucci
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/stddef.h>
#include <linux/module.h>
#include <linux/serio.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
#include <linux/mutex.h>

MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
MODULE_DESCRIPTION("Serio abstraction core");
MODULE_LICENSE("GPL");

/*
 * serio_mutex protects entire serio subsystem and is taken every time
 * serio port or driver registered or unregistered.
 */
static DEFINE_MUTEX(serio_mutex);

static LIST_HEAD(serio_list);

static void serio_add_port(struct serio *serio);
static int serio_reconnect_port(struct serio *serio);
static void serio_disconnect_port(struct serio *serio);
static void serio_reconnect_subtree(struct serio *serio);
static void serio_attach_driver(struct serio_driver *drv);

static int serio_connect_driver(struct serio *serio, struct serio_driver *drv)
{
	guard(mutex)(&serio->drv_mutex);

	return drv->connect(serio, drv);
}

static int serio_reconnect_driver(struct serio *serio)
{
	guard(mutex)(&serio->drv_mutex);

	if (serio->drv && serio->drv->reconnect)
		return serio->drv->reconnect(serio);

	return -1;
}

static void serio_disconnect_driver(struct serio *serio)
{
	guard(mutex)(&serio->drv_mutex);

	if (serio->drv)
		serio->drv->disconnect(serio);
}

static int serio_match_port(const struct serio_device_id *ids, struct serio *serio)
{
	while (ids->type || ids->proto) {
		if ((ids->type == SERIO_ANY || ids->type == serio->id.type) &&
		    (ids->proto == SERIO_ANY || ids->proto == serio->id.proto) &&
		    (ids->extra == SERIO_ANY || ids->extra == serio->id.extra) &&
		    (ids->id == SERIO_ANY || ids->id == serio->id.id))
			return 1;
		ids++;
	}
	return 0;
}

/*
 * Basic serio -> driver core mappings
 */

static int serio_bind_driver(struct serio *serio, struct serio_driver *drv)
{
	int error;

	if (serio_match_port(drv->id_table, serio)) {

		serio->dev.driver = &drv->driver;
		if (serio_connect_driver(serio, drv)) {
			serio->dev.driver = NULL;
			return -ENODEV;
		}

		error = device_bind_driver(&serio->dev);
		if (error) {
			dev_warn(&serio->dev,
				 "device_bind_driver() failed for %s (%s) and %s, error: %d\n",
				 serio->phys, serio->name,
				 drv->description, error);
			serio_disconnect_driver(serio);
			serio->dev.driver = NULL;
			return error;
		}
	}
	return 0;
}

static void serio_find_driver(struct serio *serio)
{
	int error;

	error = device_attach(&serio->dev);
	if (error < 0 && error != -EPROBE_DEFER)
		dev_warn(&serio->dev,
			 "device_attach() failed for %s (%s), error: %d\n",
			 serio->phys, serio->name, error);
}


/*
 * Serio event processing.
 */

enum serio_event_type {
	SERIO_RESCAN_PORT,
	SERIO_RECONNECT_PORT,
	SERIO_RECONNECT_SUBTREE,
	SERIO_REGISTER_PORT,
	SERIO_ATTACH_DRIVER,
};

struct serio_event {
	enum serio_event_type type;
	void *object;
	struct module *owner;
	struct list_head node;
};

static DEFINE_SPINLOCK(serio_event_lock);	/* protects serio_event_list */
static LIST_HEAD(serio_event_list);

static struct serio_event *serio_get_event(void)
{
	struct serio_event *event = NULL;

	guard(spinlock_irqsave)(&serio_event_lock);

	if (!list_empty(&serio_event_list)) {
		event = list_first_entry(&serio_event_list,
					 struct serio_event, node);
		list_del_init(&event->node);
	}

	return event;
}

static void serio_free_event(struct serio_event *event)
{
	module_put(event->owner);
	kfree(event);
}

static void serio_remove_duplicate_events(void *object,
					  enum serio_event_type type)
{
	struct serio_event *e, *next;

	guard(spinlock_irqsave)(&serio_event_lock);

	list_for_each_entry_safe(e, next, &serio_event_list, node) {
		if (object == e->object) {
			/*
			 * If this event is of different type we should not
			 * look further - we only suppress duplicate events
			 * that were sent back-to-back.
			 */
			if (type != e->type)
				break;

			list_del_init(&e->node);
			serio_free_event(e);
		}
	}
}

static void serio_handle_event(struct work_struct *work)
{
	struct serio_event *event;

	guard(mutex)(&serio_mutex);

	while ((event = serio_get_event())) {

		switch (event->type) {

		case SERIO_REGISTER_PORT:
			serio_add_port(event->object);
			break;

		case SERIO_RECONNECT_PORT:
			serio_reconnect_port(event->object);
			break;

		case SERIO_RESCAN_PORT:
			serio_disconnect_port(event->object);
			serio_find_driver(event->object);
			break;

		case SERIO_RECONNECT_SUBTREE:
			serio_reconnect_subtree(event->object);
			break;

		case SERIO_ATTACH_DRIVER:
			serio_attach_driver(event->object);
			break;
		}

		serio_remove_duplicate_events(event->object, event->type);
		serio_free_event(event);
	}
}

static DECLARE_WORK(serio_event_work, serio_handle_event);

static int serio_queue_event(void *object, struct module *owner,
			     enum serio_event_type event_type)
{
	struct serio_event *event;

	guard(spinlock_irqsave)(&serio_event_lock);

	/*
	 * Scan event list for the other events for the same serio port,
	 * starting with the most recent one. If event is the same we
	 * do not need add new one. If event is of different type we
	 * need to add this event and should not look further because
	 * we need to preseve sequence of distinct events.
	 */
	list_for_each_entry_reverse(event, &serio_event_list, node) {
		if (event->object == object) {
			if (event->type == event_type)
				return 0;
			break;
		}
	}

	event = kmalloc(sizeof(*event), GFP_ATOMIC);
	if (!event) {
		pr_err("Not enough memory to queue event %d\n", event_type);
		return -ENOMEM;
	}

	if (!try_module_get(owner)) {
		pr_warn("Can't get module reference, dropping event %d\n",
			event_type);
		kfree(event);
		return -EINVAL;
	}

	event->type = event_type;
	event->object = object;
	event->owner = owner;

	list_add_tail(&event->node, &serio_event_list);
	queue_work(system_long_wq, &serio_event_work);

	return 0;
}

/*
 * Remove all events that have been submitted for a given
 * object, be it serio port or driver.
 */
static void serio_remove_pending_events(void *object)
{
	struct serio_event *event, *next;

	guard(spinlock_irqsave)(&serio_event_lock);

	list_for_each_entry_safe(event, next, &serio_event_list, node) {
		if (event->object == object) {
			list_del_init(&event->node);
			serio_free_event(event);
		}
	}
}

/*
 * Locate child serio port (if any) that has not been fully registered yet.
 *
 * Children are registered by driver's connect() handler so there can't be a
 * grandchild pending registration together with a child.
 */
static struct serio *serio_get_pending_child(struct serio *parent)
{
	struct serio_event *event;
	struct serio *serio;

	guard(spinlock_irqsave)(&serio_event_lock);

	list_for_each_entry(event, &serio_event_list, node) {
		if (event->type == SERIO_REGISTER_PORT) {
			serio = event->object;
			if (serio->parent == parent)
				return serio;
		}
	}

	return NULL;
}

/*
 * Serio port operations
 */

static ssize_t serio_show_description(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct serio *serio = to_serio_port(dev);
	return sprintf(buf, "%s\n", serio->name);
}

static ssize_t modalias_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct serio *serio = to_serio_port(dev);

	return sprintf(buf, "serio:ty%02Xpr%02Xid%02Xex%02X\n",
			serio->id.type, serio->id.proto, serio->id.id, serio->id.extra);
}

static ssize_t type_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct serio *serio = to_serio_port(dev);
	return sprintf(buf, "%02x\n", serio->id.type);
}

static ssize_t proto_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct serio *serio = to_serio_port(dev);
	return sprintf(buf, "%02x\n", serio->id.proto);
}

static ssize_t id_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct serio *serio = to_serio_port(dev);
	return sprintf(buf, "%02x\n", serio->id.id);
}

static ssize_t extra_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct serio *serio = to_serio_port(dev);
	return sprintf(buf, "%02x\n", serio->id.extra);
}

static ssize_t drvctl_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
{
	struct serio *serio = to_serio_port(dev);
	struct device_driver *drv;
	int error;

	scoped_cond_guard(mutex_intr, return -EINTR, &serio_mutex) {
		if (!strncmp(buf, "none", count)) {
			serio_disconnect_port(serio);
		} else if (!strncmp(buf, "reconnect", count)) {
			serio_reconnect_subtree(serio);
		} else if (!strncmp(buf, "rescan", count)) {
			serio_disconnect_port(serio);
			serio_find_driver(serio);
			serio_remove_duplicate_events(serio, SERIO_RESCAN_PORT);
		} else if ((drv = driver_find(buf, &serio_bus)) != NULL) {
			serio_disconnect_port(serio);
			error = serio_bind_driver(serio, to_serio_driver(drv));
			serio_remove_duplicate_events(serio, SERIO_RESCAN_PORT);
			if (error)
				return error;
		} else {
			return -EINVAL;
		}
	}

	return count;
}

static ssize_t serio_show_bind_mode(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct serio *serio = to_serio_port(dev);
	return sprintf(buf, "%s\n", serio->manual_bind ? "manual" : "auto");
}

static ssize_t serio_set_bind_mode(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
{
	struct serio *serio = to_serio_port(dev);
	int retval;

	retval = count;
	if (!strncmp(buf, "manual", count)) {
		serio->manual_bind = true;
	} else if (!strncmp(buf, "auto", count)) {
		serio->manual_bind = false;
	} else {
		retval = -EINVAL;
	}

	return retval;
}

static ssize_t firmware_id_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct serio *serio = to_serio_port(dev);

	return sprintf(buf, "%s\n", serio->firmware_id);
}

static DEVICE_ATTR_RO(type);
static DEVICE_ATTR_RO(proto);
static DEVICE_ATTR_RO(id);
static DEVICE_ATTR_RO(extra);

static struct attribute *serio_device_id_attrs[] = {
	&dev_attr_type.attr,
	&dev_attr_proto.attr,
	&dev_attr_id.attr,
	&dev_attr_extra.attr,
	NULL
};

static const struct attribute_group serio_id_attr_group = {
	.name	= "id",
	.attrs	= serio_device_id_attrs,
};

static DEVICE_ATTR_RO(modalias);
static DEVICE_ATTR_WO(drvctl);
static DEVICE_ATTR(description, S_IRUGO, serio_show_description, NULL);
static DEVICE_ATTR(bind_mode, S_IWUSR | S_IRUGO, serio_show_bind_mode, serio_set_bind_mode);
static DEVICE_ATTR_RO(firmware_id);

static struct attribute *serio_device_attrs[] = {
	&dev_attr_modalias.attr,
	&dev_attr_description.attr,
	&dev_attr_drvctl.attr,
	&dev_attr_bind_mode.attr,
	&dev_attr_firmware_id.attr,
	NULL
};

static const struct attribute_group serio_device_attr_group = {
	.attrs	= serio_device_attrs,
};

static const struct attribute_group *serio_device_attr_groups[] = {
	&serio_id_attr_group,
	&serio_device_attr_group,
	NULL
};

static void serio_release_port(struct device *dev)
{
	struct serio *serio = to_serio_port(dev);

	kfree(serio);
	module_put(THIS_MODULE);
}

/*
 * Prepare serio port for registration.
 */
static void serio_init_port(struct serio *serio)
{
	static atomic_t serio_no = ATOMIC_INIT(-1);

	__module_get(THIS_MODULE);

	INIT_LIST_HEAD(&serio->node);
	INIT_LIST_HEAD(&serio->child_node);
	INIT_LIST_HEAD(&serio->children);
	spin_lock_init(&serio->lock);
	mutex_init(&serio->drv_mutex);
	device_initialize(&serio->dev);
	dev_set_name(&serio->dev, "serio%lu",
		     (unsigned long)atomic_inc_return(&serio_no));
	serio->dev.bus = &serio_bus;
	serio->dev.release = serio_release_port;
	serio->dev.groups = serio_device_attr_groups;
	if (serio->parent) {
		serio->dev.parent = &serio->parent->dev;
		serio->depth = serio->parent->depth + 1;
	} else
		serio->depth = 0;
	lockdep_set_subclass(&serio->lock, serio->depth);
}

/*
 * Complete serio port registration.
 * Driver core will attempt to find appropriate driver for the port.
 */
static void serio_add_port(struct serio *serio)
{
	struct serio *parent = serio->parent;
	int error;

	if (parent) {
		guard(serio_pause_rx)(parent);

		list_add_tail(&serio->child_node, &parent->children);
	}

	list_add_tail(&serio->node, &serio_list);

	if (serio->start)
		serio->start(serio);

	error = device_add(&serio->dev);
	if (error)
		dev_err(&serio->dev,
			"device_add() failed for %s (%s), error: %d\n",
			serio->phys, serio->name, error);
}

/*
 * serio_destroy_port() completes unregistration process and removes
 * port from the system
 */
static void serio_destroy_port(struct serio *serio)
{
	struct serio *child;

	while ((child = serio_get_pending_child(serio)) != NULL) {
		serio_remove_pending_events(child);
		put_device(&child->dev);
	}

	if (serio->stop)
		serio->stop(serio);

	if (serio->parent) {
		guard(serio_pause_rx)(serio->parent);

		list_del_init(&serio->child_node);
		serio->parent = NULL;
	}

	if (device_is_registered(&serio->dev))
		device_del(&serio->dev);

	list_del_init(&serio->node);
	serio_remove_pending_events(serio);
	put_device(&serio->dev);
}

/*
 * Reconnect serio port (re-initialize attached device).
 * If reconnect fails (old device is no longer attached or
 * there was no device to begin with) we do full rescan in
 * hope of finding a driver for the port.
 */
static int serio_reconnect_port(struct serio *serio)
{
	int error = serio_reconnect_driver(serio);

	if (error) {
		serio_disconnect_port(serio);
		serio_find_driver(serio);
	}

	return error;
}

/*
 * Reconnect serio port and all its children (re-initialize attached
 * devices).
 */
static void serio_reconnect_subtree(struct serio *root)
{
	struct serio *s = root;
	int error;

	do {
		error = serio_reconnect_port(s);
		if (!error) {
			/*
			 * Reconnect was successful, move on to do the
			 * first child.
			 */
			if (!list_empty(&s->children)) {
				s = list_first_entry(&s->children,
						     struct serio, child_node);
				continue;
			}
		}

		/*
		 * Either it was a leaf node or reconnect failed and it
		 * became a leaf node. Continue reconnecting starting with
		 * the next sibling of the parent node.
		 */
		while (s != root) {
			struct serio *parent = s->parent;

			if (!list_is_last(&s->child_node, &parent->children)) {
				s = list_entry(s->child_node.next,
					       struct serio, child_node);
				break;
			}

			s = parent;
		}
	} while (s != root);
}

/*
 * serio_disconnect_port() unbinds a port from its driver. As a side effect
 * all children ports are unbound and destroyed.
 */
static void serio_disconnect_port(struct serio *serio)
{
	struct serio *s = serio;

	/*
	 * Children ports should be disconnected and destroyed
	 * first; we travel the tree in depth-first order.
	 */
	while (!list_empty(&serio->children)) {

		/* Locate a leaf */
		while (!list_empty(&s->children))
			s = list_first_entry(&s->children,
					     struct serio, child_node);

		/*
		 * Prune this leaf node unless it is the one we
		 * started with.
		 */
		if (s != serio) {
			struct serio *parent = s->parent;

			device_release_driver(&s->dev);
			serio_destroy_port(s);

			s = parent;
		}
	}

	/*
	 * OK, no children left, now disconnect this port.
	 */
	device_release_driver(&serio->dev);
}

void serio_rescan(struct serio *serio)
{
	serio_queue_event(serio, NULL, SERIO_RESCAN_PORT);
}
EXPORT_SYMBOL(serio_rescan);

void serio_reconnect(struct serio *serio)
{
	serio_queue_event(serio, NULL, SERIO_RECONNECT_SUBTREE);
}
EXPORT_SYMBOL(serio_reconnect);

/*
 * Submits register request to kseriod for subsequent execution.
 * Note that port registration is always asynchronous.
 */
void __serio_register_port(struct serio *serio, struct module *owner)
{
	serio_init_port(serio);
	serio_queue_event(serio, owner, SERIO_REGISTER_PORT);
}
EXPORT_SYMBOL(__serio_register_port);

/*
 * Synchronously unregisters serio port.
 */
void serio_unregister_port(struct serio *serio)
{
	guard(mutex)(&serio_mutex);

	serio_disconnect_port(serio);
	serio_destroy_port(serio);
}
EXPORT_SYMBOL(serio_unregister_port);

/*
 * Safely unregisters children ports if they are present.
 */
void serio_unregister_child_port(struct serio *serio)
{
	struct serio *s, *next;

	guard(mutex)(&serio_mutex);

	list_for_each_entry_safe(s, next, &serio->children, child_node) {
		serio_disconnect_port(s);
		serio_destroy_port(s);
	}
}
EXPORT_SYMBOL(serio_unregister_child_port);


/*
 * Serio driver operations
 */

static ssize_t description_show(struct device_driver *drv, char *buf)
{
	struct serio_driver *driver = to_serio_driver(drv);
	return sprintf(buf, "%s\n", driver->description ? driver->description : "(none)");
}
static DRIVER_ATTR_RO(description);

static ssize_t bind_mode_show(struct device_driver *drv, char *buf)
{
	struct serio_driver *serio_drv = to_serio_driver(drv);
	return sprintf(buf, "%s\n", serio_drv->manual_bind ? "manual" : "auto");
}

static ssize_t bind_mode_store(struct device_driver *drv, const char *buf, size_t count)
{
	struct serio_driver *serio_drv = to_serio_driver(drv);
	int retval;

	retval = count;
	if (!strncmp(buf, "manual", count)) {
		serio_drv->manual_bind = true;
	} else if (!strncmp(buf, "auto", count)) {
		serio_drv->manual_bind = false;
	} else {
		retval = -EINVAL;
	}

	return retval;
}
static DRIVER_ATTR_RW(bind_mode);

static struct attribute *serio_driver_attrs[] = {
	&driver_attr_description.attr,
	&driver_attr_bind_mode.attr,
	NULL,
};
ATTRIBUTE_GROUPS(serio_driver);

static int serio_driver_probe(struct device *dev)
{
	struct serio *serio = to_serio_port(dev);
	struct serio_driver *drv = to_serio_driver(dev->driver);

	return serio_connect_driver(serio, drv);
}

static void serio_driver_remove(struct device *dev)
{
	struct serio *serio = to_serio_port(dev);

	serio_disconnect_driver(serio);
}

static void serio_cleanup(struct serio *serio)
{
	guard(mutex)(&serio->drv_mutex);

	if (serio->drv && serio->drv->cleanup)
		serio->drv->cleanup(serio);
}

static void serio_shutdown(struct device *dev)
{
	struct serio *serio = to_serio_port(dev);

	serio_cleanup(serio);
}

static void serio_attach_driver(struct serio_driver *drv)
{
	int error;

	error = driver_attach(&drv->driver);
	if (error)
		pr_warn("driver_attach() failed for %s with error %d\n",
			drv->driver.name, error);
}

int __serio_register_driver(struct serio_driver *drv, struct module *owner, const char *mod_name)
{
	bool manual_bind = drv->manual_bind;
	int error;

	drv->driver.bus = &serio_bus;
	drv->driver.owner = owner;
	drv->driver.mod_name = mod_name;

	/*
	 * Temporarily disable automatic binding because probing
	 * takes long time and we are better off doing it in kseriod
	 */
	drv->manual_bind = true;

	error = driver_register(&drv->driver);
	if (error) {
		pr_err("driver_register() failed for %s, error: %d\n",
			drv->driver.name, error);
		return error;
	}

	/*
	 * Restore original bind mode and let kseriod bind the
	 * driver to free ports
	 */
	if (!manual_bind) {
		drv->manual_bind = false;
		error = serio_queue_event(drv, NULL, SERIO_ATTACH_DRIVER);
		if (error) {
			driver_unregister(&drv->driver);
			return error;
		}
	}

	return 0;
}
EXPORT_SYMBOL(__serio_register_driver);

void serio_unregister_driver(struct serio_driver *drv)
{
	struct serio *serio;

	guard(mutex)(&serio_mutex);

	drv->manual_bind = true;	/* so serio_find_driver ignores it */
	serio_remove_pending_events(drv);

start_over:
	list_for_each_entry(serio, &serio_list, node) {
		if (serio->drv == drv) {
			serio_disconnect_port(serio);
			serio_find_driver(serio);
			/* we could've deleted some ports, restart */
			goto start_over;
		}
	}

	driver_unregister(&drv->driver);
}
EXPORT_SYMBOL(serio_unregister_driver);

static void serio_set_drv(struct serio *serio, struct serio_driver *drv)
{
	guard(serio_pause_rx)(serio);

	serio->drv = drv;
}

static int serio_bus_match(struct device *dev, const struct device_driver *drv)
{
	struct serio *serio = to_serio_port(dev);
	const struct serio_driver *serio_drv = to_serio_driver(drv);

	if (serio->manual_bind || serio_drv->manual_bind)
		return 0;

	return serio_match_port(serio_drv->id_table, serio);
}

#define SERIO_ADD_UEVENT_VAR(fmt, val...)				\
	do {								\
		int err = add_uevent_var(env, fmt, val);		\
		if (err)						\
			return err;					\
	} while (0)

static int serio_uevent(const struct device *dev, struct kobj_uevent_env *env)
{
	const struct serio *serio;

	if (!dev)
		return -ENODEV;

	serio = to_serio_port(dev);

	SERIO_ADD_UEVENT_VAR("SERIO_TYPE=%02x", serio->id.type);
	SERIO_ADD_UEVENT_VAR("SERIO_PROTO=%02x", serio->id.proto);
	SERIO_ADD_UEVENT_VAR("SERIO_ID=%02x", serio->id.id);
	SERIO_ADD_UEVENT_VAR("SERIO_EXTRA=%02x", serio->id.extra);

	SERIO_ADD_UEVENT_VAR("MODALIAS=serio:ty%02Xpr%02Xid%02Xex%02X",
				serio->id.type, serio->id.proto, serio->id.id, serio->id.extra);

	if (serio->firmware_id[0])
		SERIO_ADD_UEVENT_VAR("SERIO_FIRMWARE_ID=%s",
				     serio->firmware_id);

	return 0;
}
#undef SERIO_ADD_UEVENT_VAR

#ifdef CONFIG_PM
static int serio_suspend(struct device *dev)
{
	struct serio *serio = to_serio_port(dev);

	serio_cleanup(serio);

	return 0;
}

static int serio_resume(struct device *dev)
{
	struct serio *serio = to_serio_port(dev);
	int error = -ENOENT;

	scoped_guard(mutex, &serio->drv_mutex) {
		if (serio->drv && serio->drv->fast_reconnect) {
			error = serio->drv->fast_reconnect(serio);
			if (error && error != -ENOENT)
				dev_warn(dev, "fast reconnect failed with error %d\n",
					 error);
		}
	}

	if (error) {
		/*
		 * Driver reconnect can take a while, so better let
		 * kseriod deal with it.
		 */
		serio_queue_event(serio, NULL, SERIO_RECONNECT_PORT);
	}

	return 0;
}

static const struct dev_pm_ops serio_pm_ops = {
	.suspend	= serio_suspend,
	.resume		= serio_resume,
	.poweroff	= serio_suspend,
	.restore	= serio_resume,
};
#endif /* CONFIG_PM */

/* called from serio_driver->connect/disconnect methods under serio_mutex */
int serio_open(struct serio *serio, struct serio_driver *drv)
{
	serio_set_drv(serio, drv);

	if (serio->open && serio->open(serio)) {
		serio_set_drv(serio, NULL);
		return -1;
	}
	return 0;
}
EXPORT_SYMBOL(serio_open);

/* called from serio_driver->connect/disconnect methods under serio_mutex */
void serio_close(struct serio *serio)
{
	if (serio->close)
		serio->close(serio);

	serio_set_drv(serio, NULL);
}
EXPORT_SYMBOL(serio_close);

irqreturn_t serio_interrupt(struct serio *serio,
		unsigned char data, unsigned int dfl)
{
	guard(spinlock_irqsave)(&serio->lock);

	if (likely(serio->drv))
		return serio->drv->interrupt(serio, data, dfl);

	if (!dfl && device_is_registered(&serio->dev)) {
		serio_rescan(serio);
		return IRQ_HANDLED;
	}

	return IRQ_NONE;
}
EXPORT_SYMBOL(serio_interrupt);

const struct bus_type serio_bus = {
	.name		= "serio",
	.drv_groups	= serio_driver_groups,
	.match		= serio_bus_match,
	.uevent		= serio_uevent,
	.probe		= serio_driver_probe,
	.remove		= serio_driver_remove,
	.shutdown	= serio_shutdown,
#ifdef CONFIG_PM
	.pm		= &serio_pm_ops,
#endif
};
EXPORT_SYMBOL(serio_bus);

static int __init serio_init(void)
{
	int error;

	error = bus_register(&serio_bus);
	if (error) {
		pr_err("Failed to register serio bus, error: %d\n", error);
		return error;
	}

	return 0;
}

static void __exit serio_exit(void)
{
	bus_unregister(&serio_bus);

	/*
	 * There should not be any outstanding events but work may
	 * still be scheduled so simply cancel it.
	 */
	cancel_work_sync(&serio_event_work);
}

subsys_initcall(serio_init);
module_exit(serio_exit);