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/*

 * Generic implementation of a polled input device

 * Copyright (c) 2007 Dmitry Torokhov

 *

 * This program is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 as published by

 * the Free Software Foundation.

 */

#include <linux/jiffies.h>

#include <linux/mutex.h>

#include <linux/input-polldev.h>

MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");

MODULE_DESCRIPTION("Generic implementation of a polled input device");

MODULE_LICENSE("GPL v2");

MODULE_VERSION("0.1");

static DEFINE_MUTEX(polldev_mutex);

static int polldev_users;

static struct workqueue_struct *polldev_wq;

static int input_polldev_start_workqueue(void)

{

        int retval;

        retval = mutex_lock_interruptible(&polldev_mutex);

        if (retval)

                return retval;

        if (!polldev_users) {

                polldev_wq = create_singlethread_workqueue("ipolldevd");

                if (!polldev_wq) {

                        printk(KERN_ERR "input-polldev: failed to create "

                                "ipolldevd workqueue\n");

                        retval = -ENOMEM;

                        goto out;

                }

        }

        polldev_users++;

 out:

        mutex_unlock(&polldev_mutex);

        return retval;

}

static void input_polldev_stop_workqueue(void)

{

        mutex_lock(&polldev_mutex);

        if (!--polldev_users)

                destroy_workqueue(polldev_wq);

        mutex_unlock(&polldev_mutex);

}

static void input_polled_device_work(struct work_struct *work)

{

        struct input_polled_dev *dev =

                container_of(work, struct input_polled_dev, work.work);

        dev->poll(dev);

        queue_delayed_work(polldev_wq, &dev->work,

                           msecs_to_jiffies(dev->poll_interval));

}

static int input_open_polled_device(struct input_dev *input)

{

        struct input_polled_dev *dev = input->private;

        int error;

        unsigned long ticks;

        error = input_polldev_start_workqueue();

        if (error)

                return error;

        if (dev->flush)

                dev->flush(dev);

        ticks = msecs_to_jiffies(dev->poll_interval);

        if (ticks >= HZ)

                ticks = round_jiffies(ticks);

        queue_delayed_work(polldev_wq, &dev->work, ticks);

        return 0;

}

static void input_close_polled_device(struct input_dev *input)

{

        struct input_polled_dev *dev = input->private;

        cancel_rearming_delayed_workqueue(polldev_wq, &dev->work);

        input_polldev_stop_workqueue();

}

/**

 * input_allocate_polled_device - allocated memory polled device

 *

 * The function allocates memory for a polled device and also

 * for an input device associated with this polled device.

 */

struct input_polled_dev *input_allocate_polled_device(void)

{

        struct input_polled_dev *dev;

        dev = kzalloc(sizeof(struct input_polled_dev), GFP_KERNEL);

        if (!dev)

                return NULL;

        dev->input = input_allocate_device();

        if (!dev->input) {

                kfree(dev);

                return NULL;

        }

        return dev;

}

EXPORT_SYMBOL(input_allocate_polled_device);

/**

 * input_free_polled_device - free memory allocated for polled device

 * @dev: device to free

 *

 * The function frees memory allocated for polling device and drops

 * reference to the associated input device (if present).

 */

void input_free_polled_device(struct input_polled_dev *dev)

{

        if (dev) {

                input_free_device(dev->input);

                kfree(dev);

        }

}

EXPORT_SYMBOL(input_free_polled_device);

/**

 * input_register_polled_device - register polled device

 * @dev: device to register

 *

 * The function registers previously initialized polled input device

 * with input layer. The device should be allocated with call to

 * input_allocate_polled_device(). Callers should also set up poll()

 * method and set up capabilities (id, name, phys, bits) of the

 * corresponing input_dev structure.

 */

int input_register_polled_device(struct input_polled_dev *dev)

{

        struct input_dev *input = dev->input;

        INIT_DELAYED_WORK(&dev->work, input_polled_device_work);

        if (!dev->poll_interval)

                dev->poll_interval = 500;

        input->private = dev;

        input->open = input_open_polled_device;

        input->close = input_close_polled_device;

        return input_register_device(input);

}

EXPORT_SYMBOL(input_register_polled_device);

/**

 * input_unregister_polled_device - unregister polled device

 * @dev: device to unregister

 *

 * The function unregisters previously registered polled input

 * device from input layer. Polling is stopped and device is

 * ready to be freed with call to input_free_polled_device().

 * Callers should not attempt to access dev->input pointer

 * after calling this function.

 */

void input_unregister_polled_device(struct input_polled_dev *dev)

{

        input_unregister_device(dev->input);

        dev->input = NULL;

}

EXPORT_SYMBOL(input_unregister_polled_device);