serio.c

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/*
 *  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 <[email protected]>, or by paper mail:
 * Vojtech Pavlik, Simunkova 1594, Prague 8, 182 00 Czech Republic
 */

#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 <[email protected]>");
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 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_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)
{
    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) {
            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)
        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;
    unsigned long flags;

    spin_lock_irqsave(&serio_event_lock, flags);

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

    spin_unlock_irqrestore(&serio_event_lock, flags);
    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;
    unsigned long flags;

    spin_lock_irqsave(&serio_event_lock, flags);

    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);
        }
    }

    spin_unlock_irqrestore(&serio_event_lock, flags);
}

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

    mutex_lock(&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);
    }

    mutex_unlock(&serio_mutex);
}

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)
{
    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) {
        pr_err("Not enough memory to queue event %d\n", event_type);
        retval = -ENOMEM;
        goto out;
    }

    if (!try_module_get(owner)) {
        pr_warning("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);
    queue_work(system_long_wq, &serio_event_work);

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

/*
 * 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;
    unsigned long flags;

    spin_lock_irqsave(&serio_event_lock, flags);

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

    spin_unlock_irqrestore(&serio_event_lock, flags);
}

/*
 * 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, *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;
}

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

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_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);
    } 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);
    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%ld",
            (long)atomic_inc_return(&serio_no) - 1);
    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) {
        serio_pause_rx(parent);
        list_add_tail(&serio->child_node, &parent->children);
        serio_continue_rx(parent);
    }

    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) {
        serio_pause_rx(serio->parent);
        list_del_init(&serio->child_node);
        serio_continue_rx(serio->parent);
        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)
{
    mutex_lock(&serio_mutex);
    serio_disconnect_port(serio);
    serio_destroy_port(serio);
    mutex_unlock(&serio_mutex);
}
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;

    mutex_lock(&serio_mutex);
    list_for_each_entry_safe(s, next, &serio->children, child_node) {
        serio_disconnect_port(s);
        serio_destroy_port(s);
    }
    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)
        pr_warning("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;

    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 && device_is_registered(&serio->dev)) {
        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) {
        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);