/*
 * 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 <dtor@mail.ru>");
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
};

static const struct attribute_group *input_polldev_attribute_groups[] = {
        &input_polldev_attribute_group,
        NULL
};

/**
 * input_allocate_polled_device - allocate memory for 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);

struct input_polled_devres {
        struct input_polled_dev *polldev;
};

static int devm_input_polldev_match(struct device *dev, void *res, void *data)
{
        struct input_polled_devres *devres = res;

        return devres->polldev == data;
}

static void devm_input_polldev_release(struct device *dev, void *res)
{
        struct input_polled_devres *devres = res;
        struct input_polled_dev *polldev = devres->polldev;

        dev_dbg(dev, "%s: dropping reference/freeing %s\n",
                __func__, dev_name(&polldev->input->dev));

        input_put_device(polldev->input);
        kfree(polldev);
}

static void devm_input_polldev_unregister(struct device *dev, void *res)
{
        struct input_polled_devres *devres = res;
        struct input_polled_dev *polldev = devres->polldev;

        dev_dbg(dev, "%s: unregistering device %s\n",
                __func__, dev_name(&polldev->input->dev));
        input_unregister_device(polldev->input);

        /*
         * Note that we are still holding extra reference to the input
         * device so it will stick around until devm_input_polldev_release()
         * is called.
         */
}

/**
 * devm_input_allocate_polled_device - allocate managed polled device
 * @dev: device owning the polled device being created
 *
 * Returns prepared &struct input_polled_dev or %NULL.
 *
 * Managed polled input devices do not need to be explicitly unregistered
 * or freed as it will be done automatically when owner device unbinds
 * from * its driver (or binding fails). Once such managed polled device
 * is allocated, it is ready to be set up and registered in the same
 * fashion as regular polled input devices (using
 * input_register_polled_device() function).
 *
 * If you want to manually unregister and free such managed polled devices,
 * it can be still done by calling input_unregister_polled_device() and
 * input_free_polled_device(), although it is rarely needed.
 *
 * NOTE: the owner device is set up as parent of input device and users
 * should not override it.
 */
struct input_polled_dev *devm_input_allocate_polled_device(struct device *dev)
{
        struct input_polled_dev *polldev;
        struct input_polled_devres *devres;

        devres = devres_alloc(devm_input_polldev_release, sizeof(*devres),
                              GFP_KERNEL);
        if (!devres)
                return NULL;

        polldev = input_allocate_polled_device();
        if (!polldev) {
                devres_free(devres);
                return NULL;
        }

        polldev->input->dev.parent = dev;
        polldev->devres_managed = true;

        devres->polldev = polldev;
        devres_add(dev, devres);

        return polldev;
}
EXPORT_SYMBOL(devm_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.
 */
void input_free_polled_device(struct input_polled_dev *dev)
{
        if (dev) {
                if (dev->devres_managed)
                        WARN_ON(devres_destroy(dev->input->dev.parent,
                                                devm_input_polldev_release,
                                                devm_input_polldev_match,
                                                dev));
                input_put_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
 * corresponding input_dev structure.
 */
int input_register_polled_device(struct input_polled_dev *dev)
{
        struct input_polled_devres *devres = NULL;
        struct input_dev *input = dev->input;
        int error;

        if (dev->devres_managed) {
                devres = devres_alloc(devm_input_polldev_unregister,
                                      sizeof(*devres), GFP_KERNEL);
                if (!devres)
                        return -ENOMEM;

                devres->polldev = dev;
        }

        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;

        input->dev.groups = input_polldev_attribute_groups;

        error = input_register_device(input);
        if (error) {
                devres_free(devres);
                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);

        if (dev->devres_managed) {
                dev_dbg(input->dev.parent, "%s: registering %s with devres.\n",
                        __func__, dev_name(&input->dev));
                devres_add(input->dev.parent, devres);
        }

        return 0;
}
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().
 */
void input_unregister_polled_device(struct input_polled_dev *dev)
{
        if (dev->devres_managed)
                WARN_ON(devres_destroy(dev->input->dev.parent,
                                        devm_input_polldev_unregister,
                                        devm_input_polldev_match,
                                        dev));

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