/*
   * 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
  ", 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
  ", 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
  ", 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
  };
  
  /**
   * 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);
  
  /**
   * 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) {
  		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
   * corresponding input_dev structure.
   */
  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);
  
  /**
   * 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)
  {
  	sysfs_remove_group(&dev->input->dev.kobj,
  			   &input_polldev_attribute_group);
  
  	input_unregister_device(dev->input);
  }
  EXPORT_SYMBOL(input_unregister_polled_device);