/*
 *  The Serio abstraction module
 *
 *  Copyright (c) 1999-2004 Vojtech Pavlik
 *  Copyright (c) 2004 Dmitry Torokhov
 *  Copyright (c) 2003 Daniele Bellucci
 */

/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 * Should you need to contact me, the author, you can do so either by
 * e-mail - mail your message to <vojtech@ucw.cz>, or by paper mail:
 * Vojtech Pavlik, Simunkova 1594, Prague 8, 182 00 Czech Republic
 */

#include <linux/stddef.h>
#include <linux/module.h>
#include <linux/serio.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/kthread.h>
#include <linux/mutex.h>
#include <linux/freezer.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 registrered or unregistered.
 */
static DEFINE_MUTEX(serio_mutex);

static LIST_HEAD(serio_list);

static struct bus_type serio_bus;

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_chain(struct serio *serio);
static void serio_attach_driver(struct serio_driver *drv);

static int serio_connect_driver(struct serio *serio, struct serio_driver *drv)
{
        int retval;

        mutex_lock(&serio->drv_mutex);
        retval = drv->connect(serio, drv);
        mutex_unlock(&serio->drv_mutex);

        return retval;
}

static int serio_reconnect_driver(struct serio *serio)
{
        int retval = -1;

        mutex_lock(&serio->drv_mutex);
        if (serio->drv && serio->drv->reconnect)
                retval = serio->drv->reconnect(serio);
        mutex_unlock(&serio->drv_mutex);

        return retval;
}

static void serio_disconnect_driver(struct serio *serio)
{
        mutex_lock(&serio->drv_mutex);
        if (serio->drv)
                serio->drv->disconnect(serio);
        mutex_unlock(&serio->drv_mutex);
}

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) {
                        printk(KERN_WARNING
                                "serio: 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)
                printk(KERN_WARNING
                        "serio: 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_CHAIN,
        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 DECLARE_WAIT_QUEUE_HEAD(serio_wait);
static struct task_struct *serio_task;

static int serio_queue_event(void *object, struct module *owner,
                             enum serio_event_type event_type)
{
        unsigned long flags;
        struct serio_event *event;
        int retval = 0;

        spin_lock_irqsave(&serio_event_lock, flags);

        /*
         * 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)
                                goto out;
                        break;
                }
        }

        event = kmalloc(sizeof(struct serio_event), GFP_ATOMIC);
        if (!event) {
                printk(KERN_ERR
                        "serio: Not enough memory to queue event %d\n",
                        event_type);
                retval = -ENOMEM;
                goto out;
        }

        if (!try_module_get(owner)) {
                printk(KERN_WARNING
                        "serio: Can't get module reference, dropping event %d\n",
                        event_type);
                kfree(event);
                retval = -EINVAL;
                goto out;
        }

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

        list_add_tail(&event->node, &serio_event_list);
        wake_up(&serio_wait);

out:
        spin_unlock_irqrestore(&serio_event_lock, flags);
        return retval;
}

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

static void serio_remove_duplicate_events(struct serio_event *event)
{
        struct list_head *node, *next;
        struct serio_event *e;
        unsigned long flags;

        spin_lock_irqsave(&serio_event_lock, flags);

        list_for_each_safe(node, next, &serio_event_list) {
                e = list_entry(node, struct serio_event, node);
                if (event->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 (event->type != e->type)
                                break;

                        list_del_init(node);
                        serio_free_event(e);
                }
        }

        spin_unlock_irqrestore(&serio_event_lock, flags);
}


static struct serio_event *serio_get_event(void)
{
        struct serio_event *event;
        struct list_head *node;
        unsigned long flags;

        spin_lock_irqsave(&serio_event_lock, flags);

        if (list_empty(&serio_event_list)) {
                spin_unlock_irqrestore(&serio_event_lock, flags);
                return NULL;
        }

        node = serio_event_list.next;
        event = list_entry(node, struct serio_event, node);
        list_del_init(node);

        spin_unlock_irqrestore(&serio_event_lock, flags);

        return event;
}

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

        mutex_lock(&serio_mutex);

        /*
         * Note that we handle only one event here to give swsusp
         * a chance to freeze kseriod thread. Serio events should
         * be pretty rare so we are not concerned about taking
         * performance hit.
         */
        if ((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_CHAIN:
                                serio_reconnect_chain(event->object);
                                break;

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

                        default:
                                break;
                }

                serio_remove_duplicate_events(event);
                serio_free_event(event);
        }

        mutex_unlock(&serio_mutex);
}

/*
 * 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 list_head *node, *next;
        struct serio_event *event;
        unsigned long flags;

        spin_lock_irqsave(&serio_event_lock, flags);

        list_for_each_safe(node, next, &serio_event_list) {
                event = list_entry(node, struct serio_event, node);
                if (event->object == object) {
                        list_del_init(node);
                        serio_free_event(event);
                }
        }

        spin_unlock_irqrestore(&serio_event_lock, flags);
}

/*
 * Destroy child serio port (if any) that has not been fully registered yet.
 *
 * Note that we rely on the fact that port can have only one child and therefore
 * only one child registration request can be pending. Additionally, 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, *child = NULL;
        unsigned long flags;

        spin_lock_irqsave(&serio_event_lock, flags);

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

        spin_unlock_irqrestore(&serio_event_lock, flags);
        return child;
}

static int serio_thread(void *nothing)
{
        set_freezable();
        do {
                serio_handle_event();
                wait_event_freezable(serio_wait,
                        kthread_should_stop() || !list_empty(&serio_event_list));
        } while (!kthread_should_stop());

        printk(KERN_DEBUG "serio: kseriod exiting\n");
        return 0;
}


/*
 * 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 serio_show_modalias(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 serio_show_id_type(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 serio_show_id_proto(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 serio_show_id_id(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 serio_show_id_extra(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 DEVICE_ATTR(type, S_IRUGO, serio_show_id_type, NULL);
static DEVICE_ATTR(proto, S_IRUGO, serio_show_id_proto, NULL);
static DEVICE_ATTR(id, S_IRUGO, serio_show_id_id, NULL);
static DEVICE_ATTR(extra, S_IRUGO, serio_show_id_extra, NULL);

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

static ssize_t serio_rebind_driver(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;

        error = mutex_lock_interruptible(&serio_mutex);
        if (error)
                return error;

        if (!strncmp(buf, "none", count)) {
                serio_disconnect_port(serio);
        } else if (!strncmp(buf, "reconnect", count)) {
                serio_reconnect_chain(serio);
        } else if (!strncmp(buf, "rescan", count)) {
                serio_disconnect_port(serio);
                serio_find_driver(serio);
        } else if ((drv = driver_find(buf, &serio_bus)) != NULL) {
                serio_disconnect_port(serio);
                error = serio_bind_driver(serio, to_serio_driver(drv));
                put_driver(drv);
        } else {
                error = -EINVAL;
        }

        mutex_unlock(&serio_mutex);

        return error ? error : 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 struct device_attribute serio_device_attrs[] = {
        __ATTR(description, S_IRUGO, serio_show_description, NULL),
        __ATTR(modalias, S_IRUGO, serio_show_modalias, NULL),
        __ATTR(drvctl, S_IWUSR, NULL, serio_rebind_driver),
        __ATTR(bind_mode, S_IWUSR | S_IRUGO, serio_show_bind_mode, serio_set_bind_mode),
        __ATTR_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(0);

        __module_get(THIS_MODULE);

        INIT_LIST_HEAD(&serio->node);
        spin_lock_init(&serio->lock);
        mutex_init(&serio->drv_mutex);
        device_initialize(&serio->dev);
        dev_set_name(&serio->dev, "serio%ld",
                        (long)atomic_inc_return(&serio_no) - 1);
        serio->dev.bus = &serio_bus;
        serio->dev.release = serio_release_port;
        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)
{
        int error;

        if (serio->parent) {
                serio_pause_rx(serio->parent);
                serio->parent->child = serio;
                serio_continue_rx(serio->parent);
        }

        list_add_tail(&serio->node, &serio_list);
        if (serio->start)
                serio->start(serio);
        error = device_add(&serio->dev);
        if (error)
                printk(KERN_ERR
                        "serio: device_add() failed for %s (%s), error: %d\n",
                        serio->phys, serio->name, error);
        else {
                serio->registered = true;
                error = sysfs_create_group(&serio->dev.kobj, &serio_id_attr_group);
                if (error)
                        printk(KERN_ERR
                                "serio: sysfs_create_group() failed for %s (%s), error: %d\n",
                                serio->phys, serio->name, error);
        }
}

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

        child = serio_get_pending_child(serio);
        if (child) {
                serio_remove_pending_events(child);
                put_device(&child->dev);
        }

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

        if (serio->parent) {
                serio_pause_rx(serio->parent);
                serio->parent->child = NULL;
                serio_continue_rx(serio->parent);
                serio->parent = NULL;
        }

        if (serio->registered) {
                sysfs_remove_group(&serio->dev.kobj, &serio_id_attr_group);
                device_del(&serio->dev);
                serio->registered = false;
        }

        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_chain(struct serio *serio)
{
        do {
                if (serio_reconnect_port(serio)) {
                        /* Ok, old children are now gone, we are done */
                        break;
                }
                serio = serio->child;
        } while (serio);
}

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

        if (serio->child) {
                /*
                 * Children ports should be disconnected and destroyed
                 * first, staring with the leaf one, since we don't want
                 * to do recursion
                 */
                for (s = serio; s->child; s = s->child)
                        /* empty */;

                do {
                        parent = s->parent;

                        device_release_driver(&s->dev);
                        serio_destroy_port(s);
                } while ((s = parent) != serio);
        }

        /*
         * 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_CHAIN);
}
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)
{
        mutex_lock(&serio_mutex);
        serio_disconnect_port(serio);
        serio_destroy_port(serio);
        mutex_unlock(&serio_mutex);
}
EXPORT_SYMBOL(serio_unregister_port);

/*
 * Safely unregisters child port if one is present.
 */
void serio_unregister_child_port(struct serio *serio)
{
        mutex_lock(&serio_mutex);
        if (serio->child) {
                serio_disconnect_port(serio->child);
                serio_destroy_port(serio->child);
        }
        mutex_unlock(&serio_mutex);
}
EXPORT_SYMBOL(serio_unregister_child_port);


/*
 * Serio driver operations
 */

static ssize_t serio_driver_show_description(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 ssize_t serio_driver_show_bind_mode(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 serio_driver_set_bind_mode(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 struct driver_attribute serio_driver_attrs[] = {
        __ATTR(description, S_IRUGO, serio_driver_show_description, NULL),
        __ATTR(bind_mode, S_IWUSR | S_IRUGO,
                serio_driver_show_bind_mode, serio_driver_set_bind_mode),
        __ATTR_NULL
};

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

        serio_disconnect_driver(serio);
        return 0;
}

static void serio_cleanup(struct serio *serio)
{
        mutex_lock(&serio->drv_mutex);
        if (serio->drv && serio->drv->cleanup)
                serio->drv->cleanup(serio);
        mutex_unlock(&serio->drv_mutex);
}

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)
                printk(KERN_WARNING
                        "serio: 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) {
                printk(KERN_ERR
                        "serio: 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;

        mutex_lock(&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);
        mutex_unlock(&serio_mutex);
}
EXPORT_SYMBOL(serio_unregister_driver);

static void serio_set_drv(struct serio *serio, struct serio_driver *drv)
{
        serio_pause_rx(serio);
        serio->drv = drv;
        serio_continue_rx(serio);
}

static int serio_bus_match(struct device *dev, struct device_driver *drv)
{
        struct serio *serio = to_serio_port(dev);
        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);
}

#ifdef CONFIG_HOTPLUG

#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(struct device *dev, struct kobj_uevent_env *env)
{
        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);

        return 0;
}
#undef SERIO_ADD_UEVENT_VAR

#else

static int serio_uevent(struct device *dev, struct kobj_uevent_env *env)
{
        return -ENODEV;
}

#endif /* CONFIG_HOTPLUG */

#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);

        /*
         * 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)
{
        unsigned long flags;
        irqreturn_t ret = IRQ_NONE;

        spin_lock_irqsave(&serio->lock, flags);

        if (likely(serio->drv)) {
                ret = serio->drv->interrupt(serio, data, dfl);
        } else if (!dfl && serio->registered) {
                serio_rescan(serio);
                ret = IRQ_HANDLED;
        }

        spin_unlock_irqrestore(&serio->lock, flags);

        return ret;
}
EXPORT_SYMBOL(serio_interrupt);

static struct bus_type serio_bus = {
        .name           = "serio",
        .dev_attrs      = serio_device_attrs,
        .drv_attrs      = serio_driver_attrs,
        .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
};

static int __init serio_init(void)
{
        int error;

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

        serio_task = kthread_run(serio_thread, NULL, "kseriod");
        if (IS_ERR(serio_task)) {
                bus_unregister(&serio_bus);
                error = PTR_ERR(serio_task);
                printk(KERN_ERR "serio: Failed to start kseriod, error: %d\n", error);
                return error;
        }

        return 0;
}

static void __exit serio_exit(void)
{
        bus_unregister(&serio_bus);
        kthread_stop(serio_task);
}

subsys_initcall(serio_init);
module_exit(serio_exit);