input-polldev.c

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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.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/jiffies.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/workqueue.h>
#include <linux/module.h>
#include <linux/input-polldev.h>

MODULE_AUTHOR("Dmitry Torokhov <[email protected]>");
MODULE_DESCRIPTION("Generic implementation of a polled input device");
MODULE_LICENSE("GPL v2");
MODULE_VERSION("0.1");

static void input_polldev_queue_work(struct input_polled_dev *dev)
{
    unsigned long delay;

    delay = msecs_to_jiffies(dev->poll_interval);
    if (delay >= HZ)
        delay = round_jiffies_relative(delay);

    queue_delayed_work(system_freezable_wq, &dev->work, delay);
}

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);
    input_polldev_queue_work(dev);
}

static int input_open_polled_device(struct input_dev *input)
{
    struct input_polled_dev *dev = input_get_drvdata(input);

    if (dev->open)
        dev->open(dev);

    /* Only start polling if polling is enabled */
    if (dev->poll_interval > 0) {
        dev->poll(dev);
        input_polldev_queue_work(dev);
    }

    return 0;
}

static void input_close_polled_device(struct input_dev *input)
{
    struct input_polled_dev *dev = input_get_drvdata(input);

    cancel_delayed_work_sync(&dev->work);

    if (dev->close)
        dev->close(dev);
}

/* SYSFS interface */

static ssize_t input_polldev_get_poll(struct device *dev,
                      struct device_attribute *attr, char *buf)
{
    struct input_polled_dev *polldev = dev_get_drvdata(dev);

    return sprintf(buf, "%d\n", polldev->poll_interval);
}

static ssize_t input_polldev_set_poll(struct device *dev,
                struct device_attribute *attr, const char *buf,
                size_t count)
{
    struct input_polled_dev *polldev = dev_get_drvdata(dev);
    struct input_dev *input = polldev->input;
    unsigned int interval;
    int err;

    err = kstrtouint(buf, 0, &interval);
    if (err)
        return err;

    if (interval < polldev->poll_interval_min)
        return -EINVAL;

    if (interval > polldev->poll_interval_max)
        return -EINVAL;

    mutex_lock(&input->mutex);

    polldev->poll_interval = interval;

    if (input->users) {
        cancel_delayed_work_sync(&polldev->work);
        if (polldev->poll_interval > 0)
            input_polldev_queue_work(polldev);
    }

    mutex_unlock(&input->mutex);

    return count;
}

static DEVICE_ATTR(poll, S_IRUGO | S_IWUSR, input_polldev_get_poll,
                        input_polldev_set_poll);


static ssize_t input_polldev_get_max(struct device *dev,
                     struct device_attribute *attr, char *buf)
{
    struct input_polled_dev *polldev = dev_get_drvdata(dev);

    return sprintf(buf, "%d\n", polldev->poll_interval_max);
}

static DEVICE_ATTR(max, S_IRUGO, input_polldev_get_max, NULL);

static ssize_t input_polldev_get_min(struct device *dev,
                     struct device_attribute *attr, char *buf)
{
    struct input_polled_dev *polldev = dev_get_drvdata(dev);

    return sprintf(buf, "%d\n", polldev->poll_interval_min);
}

static DEVICE_ATTR(min, S_IRUGO, input_polldev_get_min, NULL);

static struct attribute *sysfs_attrs[] = {
    &dev_attr_poll.attr,
    &dev_attr_max.attr,
    &dev_attr_min.attr,
    NULL
};

static struct attribute_group input_polldev_attribute_group = {
    .attrs = sysfs_attrs
};

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);

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);

int input_register_polled_device(struct input_polled_dev *dev)
{
    struct input_dev *input = dev->input;
    int error;

    input_set_drvdata(input, dev);
    INIT_DELAYED_WORK(&dev->work, input_polled_device_work);
    if (!dev->poll_interval)
        dev->poll_interval = 500;
    if (!dev->poll_interval_max)
        dev->poll_interval_max = dev->poll_interval;
    input->open = input_open_polled_device;
    input->close = input_close_polled_device;

    error = input_register_device(input);
    if (error)
        return error;

    error = sysfs_create_group(&input->dev.kobj,
                   &input_polldev_attribute_group);
    if (error) {
        input_unregister_device(input);
        return error;
    }

    /*
     * Take extra reference to the underlying input device so
     * that it survives call to input_unregister_polled_device()
     * and is deleted only after input_free_polled_device()
     * has been invoked. This is needed to ease task of freeing
     * sparse keymaps.
     */
    input_get_device(input);

    return 0;
}
EXPORT_SYMBOL(input_register_polled_device);

void input_unregister_polled_device(struct input_polled_dev *dev)
{
    sysfs_remove_group(&dev->input->dev.kobj,
               &input_polldev_attribute_group);

    input_unregister_device(dev->input);
}
EXPORT_SYMBOL(input_unregister_polled_device);