/* * 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);	unsigned long delay; 	dev->poll(dev); 	delay = msecs_to_jiffies(dev->poll_interval);	if (delay >= HZ)		delay = round_jiffies_relative(delay); 	queue_delayed_work(polldev_wq, &dev->work, delay);} static int input_open_polled_device(struct input_dev *input){	struct input_polled_dev *dev = input->private;	int error; 	error = input_polldev_start_workqueue();	if (error)		return error; 	if (dev->flush)		dev->flush(dev); 	queue_delayed_work(polldev_wq, &dev->work,			   msecs_to_jiffies(dev->poll_interval)); 	return 0;} static void input_close_polled_device(struct input_dev *input){	struct input_polled_dev *dev = input->private; 	cancel_delayed_work_sync(&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);