/*
   * Event char devices, giving access to raw input device events.
   *
   * Copyright (c) 1999-2002 Vojtech Pavlik
   *
   * 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

  #define EVDEV_MINOR_BASE	64
  #define EVDEV_MINORS		32

  #define EVDEV_MIN_BUFFER_SIZE	64U
  #define EVDEV_BUF_PACKETS	8

  
  #include <linux/poll.h>

  #include <linux/sched.h>

  #include <linux/slab.h>
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/input.h>
  #include <linux/major.h>

  #include <linux/device.h>

  #include "input-compat.h"

  
  struct evdev {

  	int open;
  	int minor;

  	struct input_handle handle;
  	wait_queue_head_t wait;

  	struct evdev_client __rcu *grab;

  	struct list_head client_list;

  	spinlock_t client_lock; /* protects client_list */
  	struct mutex mutex;

  	struct device dev;

  	bool exist;

  };

  struct evdev_client {

  	unsigned int head;
  	unsigned int tail;

  	unsigned int packet_head; /* [future] position of the first element of next packet */

  	spinlock_t buffer_lock; /* protects access to buffer, head and tail */

  	struct fasync_struct *fasync;
  	struct evdev *evdev;
  	struct list_head node;

  	unsigned int bufsize;

  	struct input_event buffer[];

  };
  
  static struct evdev *evdev_table[EVDEV_MINORS];

  static DEFINE_MUTEX(evdev_table_mutex);

  static void evdev_pass_event(struct evdev_client *client,
  			     struct input_event *event)
  {

  	/* Interrupts are disabled, just acquire the lock. */

  	spin_lock(&client->buffer_lock);

  
  	client->buffer[client->head++] = *event;
  	client->head &= client->bufsize - 1;
  
  	if (unlikely(client->head == client->tail)) {
  		/*
  		 * This effectively "drops" all unconsumed events, leaving
  		 * EV_SYN/SYN_DROPPED plus the newest event in the queue.
  		 */
  		client->tail = (client->head - 2) & (client->bufsize - 1);
  
  		client->buffer[client->tail].time = event->time;
  		client->buffer[client->tail].type = EV_SYN;
  		client->buffer[client->tail].code = SYN_DROPPED;
  		client->buffer[client->tail].value = 0;

  		client->packet_head = client->tail;
  	}

  	if (event->type == EV_SYN && event->code == SYN_REPORT) {
  		client->packet_head = client->head;

  		kill_fasync(&client->fasync, SIGIO, POLL_IN);

  	}
  
  	spin_unlock(&client->buffer_lock);

  }
  
  /*

   * Pass incoming event to all connected clients.

   */
  static void evdev_event(struct input_handle *handle,
  			unsigned int type, unsigned int code, int value)

  {
  	struct evdev *evdev = handle->private;

  	struct evdev_client *client;

  	struct input_event event;

  	do_gettimeofday(&event.time);
  	event.type = type;
  	event.code = code;
  	event.value = value;

  	rcu_read_lock();

  	client = rcu_dereference(evdev->grab);
  	if (client)
  		evdev_pass_event(client, &event);
  	else
  		list_for_each_entry_rcu(client, &evdev->client_list, node)
  			evdev_pass_event(client, &event);

  	rcu_read_unlock();

  	if (type == EV_SYN && code == SYN_REPORT)
  		wake_up_interruptible(&evdev->wait);

  }
  
  static int evdev_fasync(int fd, struct file *file, int on)
  {

  	struct evdev_client *client = file->private_data;

  	return fasync_helper(fd, file, on, &client->fasync);

  }

  static int evdev_flush(struct file *file, fl_owner_t id)

  {

  	struct evdev_client *client = file->private_data;
  	struct evdev *evdev = client->evdev;

  	int retval;
  
  	retval = mutex_lock_interruptible(&evdev->mutex);
  	if (retval)
  		return retval;

  	if (!evdev->exist)

  		retval = -ENODEV;
  	else
  		retval = input_flush_device(&evdev->handle, file);

  	mutex_unlock(&evdev->mutex);
  	return retval;

  }

  static void evdev_free(struct device *dev)

  {

  	struct evdev *evdev = container_of(dev, struct evdev, dev);

  	input_put_device(evdev->handle.dev);

  	kfree(evdev);
  }

  /*
   * Grabs an event device (along with underlying input device).
   * This function is called with evdev->mutex taken.
   */
  static int evdev_grab(struct evdev *evdev, struct evdev_client *client)
  {
  	int error;
  
  	if (evdev->grab)
  		return -EBUSY;
  
  	error = input_grab_device(&evdev->handle);
  	if (error)
  		return error;
  
  	rcu_assign_pointer(evdev->grab, client);

  
  	return 0;
  }
  
  static int evdev_ungrab(struct evdev *evdev, struct evdev_client *client)
  {
  	if (evdev->grab != client)
  		return  -EINVAL;
  
  	rcu_assign_pointer(evdev->grab, NULL);

  	synchronize_rcu();

  	input_release_device(&evdev->handle);
  
  	return 0;
  }
  
  static void evdev_attach_client(struct evdev *evdev,
  				struct evdev_client *client)
  {
  	spin_lock(&evdev->client_lock);
  	list_add_tail_rcu(&client->node, &evdev->client_list);
  	spin_unlock(&evdev->client_lock);

  }
  
  static void evdev_detach_client(struct evdev *evdev,
  				struct evdev_client *client)
  {
  	spin_lock(&evdev->client_lock);
  	list_del_rcu(&client->node);
  	spin_unlock(&evdev->client_lock);

  	synchronize_rcu();

  }
  
  static int evdev_open_device(struct evdev *evdev)
  {
  	int retval;
  
  	retval = mutex_lock_interruptible(&evdev->mutex);
  	if (retval)
  		return retval;
  
  	if (!evdev->exist)
  		retval = -ENODEV;

  	else if (!evdev->open++) {

  		retval = input_open_device(&evdev->handle);

  		if (retval)
  			evdev->open--;
  	}

  
  	mutex_unlock(&evdev->mutex);
  	return retval;
  }
  
  static void evdev_close_device(struct evdev *evdev)
  {
  	mutex_lock(&evdev->mutex);
  
  	if (evdev->exist && !--evdev->open)
  		input_close_device(&evdev->handle);
  
  	mutex_unlock(&evdev->mutex);
  }
  
  /*
   * Wake up users waiting for IO so they can disconnect from
   * dead device.
   */
  static void evdev_hangup(struct evdev *evdev)
  {
  	struct evdev_client *client;
  
  	spin_lock(&evdev->client_lock);
  	list_for_each_entry(client, &evdev->client_list, node)
  		kill_fasync(&client->fasync, SIGIO, POLL_HUP);
  	spin_unlock(&evdev->client_lock);
  
  	wake_up_interruptible(&evdev->wait);
  }

  static int evdev_release(struct inode *inode, struct file *file)

  {

  	struct evdev_client *client = file->private_data;
  	struct evdev *evdev = client->evdev;

  	mutex_lock(&evdev->mutex);
  	if (evdev->grab == client)
  		evdev_ungrab(evdev, client);
  	mutex_unlock(&evdev->mutex);

  	evdev_detach_client(evdev, client);

  	kfree(client);

  	evdev_close_device(evdev);

  	put_device(&evdev->dev);

  	return 0;
  }

  static unsigned int evdev_compute_buffer_size(struct input_dev *dev)
  {

  	unsigned int n_events =
  		max(dev->hint_events_per_packet * EVDEV_BUF_PACKETS,
  		    EVDEV_MIN_BUFFER_SIZE);
  
  	return roundup_pow_of_two(n_events);

  }

  static int evdev_open(struct inode *inode, struct file *file)

  {

  	struct evdev *evdev;

  	struct evdev_client *client;

  	int i = iminor(inode) - EVDEV_MINOR_BASE;

  	unsigned int bufsize;

  	int error;

  	if (i >= EVDEV_MINORS)

  		return -ENODEV;

  	error = mutex_lock_interruptible(&evdev_table_mutex);
  	if (error)
  		return error;

  	evdev = evdev_table[i];

  	if (evdev)
  		get_device(&evdev->dev);
  	mutex_unlock(&evdev_table_mutex);

  	if (!evdev)

  		return -ENODEV;

  	bufsize = evdev_compute_buffer_size(evdev->handle.dev);
  
  	client = kzalloc(sizeof(struct evdev_client) +
  				bufsize * sizeof(struct input_event),
  			 GFP_KERNEL);

  	if (!client) {
  		error = -ENOMEM;
  		goto err_put_evdev;
  	}

  	client->bufsize = bufsize;

  	spin_lock_init(&client->buffer_lock);

  	client->evdev = evdev;

  	evdev_attach_client(evdev, client);

  	error = evdev_open_device(evdev);
  	if (error)
  		goto err_free_client;

  	file->private_data = client;

  	nonseekable_open(inode, file);

  	return 0;

  
   err_free_client:

  	evdev_detach_client(evdev, client);

  	kfree(client);
   err_put_evdev:
  	put_device(&evdev->dev);
  	return error;

  }

  static ssize_t evdev_write(struct file *file, const char __user *buffer,
  			   size_t count, loff_t *ppos)

  {

  	struct evdev_client *client = file->private_data;
  	struct evdev *evdev = client->evdev;

  	struct input_event event;

  	int retval;

  	if (count < input_event_size())
  		return -EINVAL;

  	retval = mutex_lock_interruptible(&evdev->mutex);
  	if (retval)
  		return retval;
  
  	if (!evdev->exist) {
  		retval = -ENODEV;
  		goto out;
  	}

  	do {

  		if (input_event_from_user(buffer + retval, &event)) {

  			retval = -EFAULT;
  			goto out;
  		}

  		retval += input_event_size();

  
  		input_inject_event(&evdev->handle,
  				   event.type, event.code, event.value);

  	} while (retval + input_event_size() <= count);

   out:
  	mutex_unlock(&evdev->mutex);

  	return retval;
  }

  static int evdev_fetch_next_event(struct evdev_client *client,
  				  struct input_event *event)
  {
  	int have_event;
  
  	spin_lock_irq(&client->buffer_lock);
  
  	have_event = client->head != client->tail;
  	if (have_event) {
  		*event = client->buffer[client->tail++];

  		client->tail &= client->bufsize - 1;

  	}
  
  	spin_unlock_irq(&client->buffer_lock);
  
  	return have_event;
  }
  
  static ssize_t evdev_read(struct file *file, char __user *buffer,
  			  size_t count, loff_t *ppos)

  {

  	struct evdev_client *client = file->private_data;
  	struct evdev *evdev = client->evdev;

  	struct input_event event;

  	int retval;

  	if (count < input_event_size())

  		return -EINVAL;

  	if (client->packet_head == client->tail && evdev->exist &&

  	    (file->f_flags & O_NONBLOCK))

  		return -EAGAIN;

  	retval = wait_event_interruptible(evdev->wait,

  		client->packet_head != client->tail || !evdev->exist);

  	if (retval)
  		return retval;

  	if (!evdev->exist)

  		return -ENODEV;

  	while (retval + input_event_size() <= count &&

  	       evdev_fetch_next_event(client, &event)) {

  		if (input_event_to_user(buffer + retval, &event))

  			return -EFAULT;

  		retval += input_event_size();

  	}
  
  	return retval;
  }
  
  /* No kernel lock - fine */
  static unsigned int evdev_poll(struct file *file, poll_table *wait)
  {

  	struct evdev_client *client = file->private_data;
  	struct evdev *evdev = client->evdev;

  	unsigned int mask;

  	poll_wait(file, &evdev->wait, wait);

  
  	mask = evdev->exist ? POLLOUT | POLLWRNORM : POLLHUP | POLLERR;

  	if (client->packet_head != client->tail)

  		mask |= POLLIN | POLLRDNORM;
  
  	return mask;

  }

  #ifdef CONFIG_COMPAT
  
  #define BITS_PER_LONG_COMPAT (sizeof(compat_long_t) * 8)

  #define BITS_TO_LONGS_COMPAT(x) ((((x) - 1) / BITS_PER_LONG_COMPAT) + 1)

  
  #ifdef __BIG_ENDIAN
  static int bits_to_user(unsigned long *bits, unsigned int maxbit,
  			unsigned int maxlen, void __user *p, int compat)
  {
  	int len, i;
  
  	if (compat) {

  		len = BITS_TO_LONGS_COMPAT(maxbit) * sizeof(compat_long_t);

  		if (len > maxlen)

  			len = maxlen;
  
  		for (i = 0; i < len / sizeof(compat_long_t); i++)
  			if (copy_to_user((compat_long_t __user *) p + i,
  					 (compat_long_t *) bits +
  						i + 1 - ((i % 2) << 1),
  					 sizeof(compat_long_t)))
  				return -EFAULT;
  	} else {

  		len = BITS_TO_LONGS(maxbit) * sizeof(long);

  		if (len > maxlen)
  			len = maxlen;
  
  		if (copy_to_user(p, bits, len))
  			return -EFAULT;
  	}
  
  	return len;
  }
  #else
  static int bits_to_user(unsigned long *bits, unsigned int maxbit,
  			unsigned int maxlen, void __user *p, int compat)
  {
  	int len = compat ?

  			BITS_TO_LONGS_COMPAT(maxbit) * sizeof(compat_long_t) :
  			BITS_TO_LONGS(maxbit) * sizeof(long);

  
  	if (len > maxlen)
  		len = maxlen;
  
  	return copy_to_user(p, bits, len) ? -EFAULT : len;
  }
  #endif /* __BIG_ENDIAN */
  
  #else
  
  static int bits_to_user(unsigned long *bits, unsigned int maxbit,
  			unsigned int maxlen, void __user *p, int compat)
  {

  	int len = BITS_TO_LONGS(maxbit) * sizeof(long);

  
  	if (len > maxlen)
  		len = maxlen;
  
  	return copy_to_user(p, bits, len) ? -EFAULT : len;
  }
  
  #endif /* CONFIG_COMPAT */
  
  static int str_to_user(const char *str, unsigned int maxlen, void __user *p)
  {
  	int len;
  
  	if (!str)
  		return -ENOENT;
  
  	len = strlen(str) + 1;
  	if (len > maxlen)
  		len = maxlen;
  
  	return copy_to_user(p, str, len) ? -EFAULT : len;
  }

  #define OLD_KEY_MAX	0x1ff

  static int handle_eviocgbit(struct input_dev *dev,
  			    unsigned int type, unsigned int size,
  			    void __user *p, int compat_mode)

  {

  	static unsigned long keymax_warn_time;

  	unsigned long *bits;
  	int len;

  	switch (type) {

  
  	case      0: bits = dev->evbit;  len = EV_MAX;  break;
  	case EV_KEY: bits = dev->keybit; len = KEY_MAX; break;
  	case EV_REL: bits = dev->relbit; len = REL_MAX; break;
  	case EV_ABS: bits = dev->absbit; len = ABS_MAX; break;
  	case EV_MSC: bits = dev->mscbit; len = MSC_MAX; break;
  	case EV_LED: bits = dev->ledbit; len = LED_MAX; break;
  	case EV_SND: bits = dev->sndbit; len = SND_MAX; break;
  	case EV_FF:  bits = dev->ffbit;  len = FF_MAX;  break;
  	case EV_SW:  bits = dev->swbit;  len = SW_MAX;  break;
  	default: return -EINVAL;
  	}

  
  	/*
  	 * Work around bugs in userspace programs that like to do
  	 * EVIOCGBIT(EV_KEY, KEY_MAX) and not realize that 'len'
  	 * should be in bytes, not in bits.
  	 */

  	if (type == EV_KEY && size == OLD_KEY_MAX) {

  		len = OLD_KEY_MAX;
  		if (printk_timed_ratelimit(&keymax_warn_time, 10 * 1000))

  			pr_warning("(EVIOCGBIT): Suspicious buffer size %u, "
  				   "limiting output to %zu bytes. See "
  				   "http://userweb.kernel.org/~dtor/eviocgbit-bug.html
  ",
  				   OLD_KEY_MAX,
  				   BITS_TO_LONGS(OLD_KEY_MAX) * sizeof(long));

  	}

  	return bits_to_user(bits, len, size, p, compat_mode);

  }

  #undef OLD_KEY_MAX

  static int evdev_handle_get_keycode(struct input_dev *dev, void __user *p)

  {

  	struct input_keymap_entry ke = {
  		.len	= sizeof(unsigned int),
  		.flags	= 0,
  	};
  	int __user *ip = (int __user *)p;

  	int error;

  	/* legacy case */
  	if (copy_from_user(ke.scancode, p, sizeof(unsigned int)))
  		return -EFAULT;

  	error = input_get_keycode(dev, &ke);
  	if (error)
  		return error;

  	if (put_user(ke.keycode, ip + 1))
  		return -EFAULT;

  	return 0;
  }

  static int evdev_handle_get_keycode_v2(struct input_dev *dev, void __user *p)
  {
  	struct input_keymap_entry ke;
  	int error;

  	if (copy_from_user(&ke, p, sizeof(ke)))
  		return -EFAULT;

  	error = input_get_keycode(dev, &ke);
  	if (error)
  		return error;

  	if (copy_to_user(p, &ke, sizeof(ke)))
  		return -EFAULT;

  	return 0;
  }

  static int evdev_handle_set_keycode(struct input_dev *dev, void __user *p)

  {

  	struct input_keymap_entry ke = {
  		.len	= sizeof(unsigned int),
  		.flags	= 0,
  	};
  	int __user *ip = (int __user *)p;

  	if (copy_from_user(ke.scancode, p, sizeof(unsigned int)))
  		return -EFAULT;

  	if (get_user(ke.keycode, ip + 1))
  		return -EFAULT;

  	return input_set_keycode(dev, &ke);
  }

  static int evdev_handle_set_keycode_v2(struct input_dev *dev, void __user *p)
  {
  	struct input_keymap_entry ke;

  	if (copy_from_user(&ke, p, sizeof(ke)))
  		return -EFAULT;

  	if (ke.len > sizeof(ke.scancode))
  		return -EINVAL;

  
  	return input_set_keycode(dev, &ke);
  }

  static long evdev_do_ioctl(struct file *file, unsigned int cmd,
  			   void __user *p, int compat_mode)

  {

  	struct evdev_client *client = file->private_data;
  	struct evdev *evdev = client->evdev;

  	struct input_dev *dev = evdev->handle.dev;
  	struct input_absinfo abs;

  	struct ff_effect effect;

  	int __user *ip = (int __user *)p;

  	unsigned int i, t, u, v;

  	unsigned int size;

  	int error;

  	/* First we check for fixed-length commands */

  	switch (cmd) {

  	case EVIOCGVERSION:
  		return put_user(EV_VERSION, ip);

  	case EVIOCGID:
  		if (copy_to_user(p, &dev->id, sizeof(struct input_id)))
  			return -EFAULT;
  		return 0;

  	case EVIOCGREP:
  		if (!test_bit(EV_REP, dev->evbit))
  			return -ENOSYS;
  		if (put_user(dev->rep[REP_DELAY], ip))
  			return -EFAULT;
  		if (put_user(dev->rep[REP_PERIOD], ip + 1))
  			return -EFAULT;
  		return 0;

  	case EVIOCSREP:
  		if (!test_bit(EV_REP, dev->evbit))
  			return -ENOSYS;
  		if (get_user(u, ip))
  			return -EFAULT;
  		if (get_user(v, ip + 1))
  			return -EFAULT;

  		input_inject_event(&evdev->handle, EV_REP, REP_DELAY, u);
  		input_inject_event(&evdev->handle, EV_REP, REP_PERIOD, v);

  		return 0;

  	case EVIOCRMFF:
  		return input_ff_erase(dev, (int)(unsigned long) p, file);

  	case EVIOCGEFFECTS:
  		i = test_bit(EV_FF, dev->evbit) ?
  				dev->ff->max_effects : 0;
  		if (put_user(i, ip))
  			return -EFAULT;
  		return 0;
  
  	case EVIOCGRAB:
  		if (p)
  			return evdev_grab(evdev, client);
  		else
  			return evdev_ungrab(evdev, client);

  
  	case EVIOCGKEYCODE:
  		return evdev_handle_get_keycode(dev, p);
  
  	case EVIOCSKEYCODE:
  		return evdev_handle_set_keycode(dev, p);
  
  	case EVIOCGKEYCODE_V2:
  		return evdev_handle_get_keycode_v2(dev, p);
  
  	case EVIOCSKEYCODE_V2:
  		return evdev_handle_set_keycode_v2(dev, p);

  	}

  	size = _IOC_SIZE(cmd);

  	/* Now check variable-length commands */
  #define EVIOC_MASK_SIZE(nr)	((nr) & ~(_IOC_SIZEMASK << _IOC_SIZESHIFT))

  	switch (EVIOC_MASK_SIZE(cmd)) {

  	case EVIOCGPROP(0):
  		return bits_to_user(dev->propbit, INPUT_PROP_MAX,
  				    size, p, compat_mode);

  	case EVIOCGKEY(0):
  		return bits_to_user(dev->key, KEY_MAX, size, p, compat_mode);

  	case EVIOCGLED(0):
  		return bits_to_user(dev->led, LED_MAX, size, p, compat_mode);

  	case EVIOCGSND(0):
  		return bits_to_user(dev->snd, SND_MAX, size, p, compat_mode);

  	case EVIOCGSW(0):
  		return bits_to_user(dev->sw, SW_MAX, size, p, compat_mode);

  	case EVIOCGNAME(0):
  		return str_to_user(dev->name, size, p);

  	case EVIOCGPHYS(0):
  		return str_to_user(dev->phys, size, p);

  	case EVIOCGUNIQ(0):
  		return str_to_user(dev->uniq, size, p);

  	case EVIOC_MASK_SIZE(EVIOCSFF):
  		if (input_ff_effect_from_user(p, size, &effect))
  			return -EFAULT;

  		error = input_ff_upload(dev, &effect, file);

  		if (put_user(effect.id, &(((struct ff_effect __user *)p)->id)))
  			return -EFAULT;

  		return error;
  	}

  	/* Multi-number variable-length handlers */
  	if (_IOC_TYPE(cmd) != 'E')
  		return -EINVAL;

  	if (_IOC_DIR(cmd) == _IOC_READ) {

  		if ((_IOC_NR(cmd) & ~EV_MAX) == _IOC_NR(EVIOCGBIT(0, 0)))
  			return handle_eviocgbit(dev,
  						_IOC_NR(cmd) & EV_MAX, size,
  						p, compat_mode);

  		if ((_IOC_NR(cmd) & ~ABS_MAX) == _IOC_NR(EVIOCGABS(0))) {

  			if (!dev->absinfo)
  				return -EINVAL;

  			t = _IOC_NR(cmd) & ABS_MAX;
  			abs = dev->absinfo[t];

  			if (copy_to_user(p, &abs, min_t(size_t,
  					size, sizeof(struct input_absinfo))))
  				return -EFAULT;

  			return 0;
  		}
  	}

  	if (_IOC_DIR(cmd) == _IOC_WRITE) {

  		if ((_IOC_NR(cmd) & ~ABS_MAX) == _IOC_NR(EVIOCSABS(0))) {

  			if (!dev->absinfo)
  				return -EINVAL;

  			t = _IOC_NR(cmd) & ABS_MAX;

  			if (copy_from_user(&abs, p, min_t(size_t,
  					size, sizeof(struct input_absinfo))))
  				return -EFAULT;

  			if (size < sizeof(struct input_absinfo))
  				abs.resolution = 0;

  			/* We can't change number of reserved MT slots */
  			if (t == ABS_MT_SLOT)
  				return -EINVAL;

  			/*
  			 * Take event lock to ensure that we are not
  			 * changing device parameters in the middle
  			 * of event.
  			 */
  			spin_lock_irq(&dev->event_lock);
  			dev->absinfo[t] = abs;
  			spin_unlock_irq(&dev->event_lock);

  			return 0;

  		}

  	}

  	return -EINVAL;
  }

  static long evdev_ioctl_handler(struct file *file, unsigned int cmd,
  				void __user *p, int compat_mode)
  {
  	struct evdev_client *client = file->private_data;
  	struct evdev *evdev = client->evdev;
  	int retval;
  
  	retval = mutex_lock_interruptible(&evdev->mutex);
  	if (retval)
  		return retval;
  
  	if (!evdev->exist) {
  		retval = -ENODEV;
  		goto out;
  	}
  
  	retval = evdev_do_ioctl(file, cmd, p, compat_mode);
  
   out:
  	mutex_unlock(&evdev->mutex);
  	return retval;
  }

  static long evdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
  {
  	return evdev_ioctl_handler(file, cmd, (void __user *)arg, 0);
  }

  #ifdef CONFIG_COMPAT

  static long evdev_ioctl_compat(struct file *file,
  				unsigned int cmd, unsigned long arg)

  {

  	return evdev_ioctl_handler(file, cmd, compat_ptr(arg), 1);

  }

  #endif

  static const struct file_operations evdev_fops = {

  	.owner		= THIS_MODULE,
  	.read		= evdev_read,
  	.write		= evdev_write,
  	.poll		= evdev_poll,
  	.open		= evdev_open,
  	.release	= evdev_release,
  	.unlocked_ioctl	= evdev_ioctl,

  #ifdef CONFIG_COMPAT

  	.compat_ioctl	= evdev_ioctl_compat,

  #endif

  	.fasync		= evdev_fasync,

  	.flush		= evdev_flush,
  	.llseek		= no_llseek,

  };

  static int evdev_install_chrdev(struct evdev *evdev)
  {
  	/*
  	 * No need to do any locking here as calls to connect and
  	 * disconnect are serialized by the input core
  	 */
  	evdev_table[evdev->minor] = evdev;
  	return 0;
  }
  
  static void evdev_remove_chrdev(struct evdev *evdev)
  {
  	/*
  	 * Lock evdev table to prevent race with evdev_open()
  	 */
  	mutex_lock(&evdev_table_mutex);
  	evdev_table[evdev->minor] = NULL;
  	mutex_unlock(&evdev_table_mutex);
  }
  
  /*
   * Mark device non-existent. This disables writes, ioctls and
   * prevents new users from opening the device. Already posted
   * blocking reads will stay, however new ones will fail.
   */
  static void evdev_mark_dead(struct evdev *evdev)
  {
  	mutex_lock(&evdev->mutex);

  	evdev->exist = false;

  	mutex_unlock(&evdev->mutex);
  }
  
  static void evdev_cleanup(struct evdev *evdev)
  {
  	struct input_handle *handle = &evdev->handle;
  
  	evdev_mark_dead(evdev);
  	evdev_hangup(evdev);
  	evdev_remove_chrdev(evdev);
  
  	/* evdev is marked dead so no one else accesses evdev->open */
  	if (evdev->open) {
  		input_flush_device(handle, NULL);
  		input_close_device(handle);
  	}
  }
  
  /*
   * Create new evdev device. Note that input core serializes calls
   * to connect and disconnect so we don't need to lock evdev_table here.
   */

  static int evdev_connect(struct input_handler *handler, struct input_dev *dev,
  			 const struct input_device_id *id)

  {
  	struct evdev *evdev;
  	int minor;

  	int error;

  	for (minor = 0; minor < EVDEV_MINORS; minor++)
  		if (!evdev_table[minor])
  			break;

  	if (minor == EVDEV_MINORS) {

  		pr_err("no more free evdev devices
  ");

  		return -ENFILE;

  	}

  	evdev = kzalloc(sizeof(struct evdev), GFP_KERNEL);
  	if (!evdev)
  		return -ENOMEM;

  	INIT_LIST_HEAD(&evdev->client_list);

  	spin_lock_init(&evdev->client_lock);
  	mutex_init(&evdev->mutex);

  	init_waitqueue_head(&evdev->wait);

  	dev_set_name(&evdev->dev, "event%d", minor);

  	evdev->exist = true;

  	evdev->minor = minor;

  	evdev->handle.dev = input_get_device(dev);

  	evdev->handle.name = dev_name(&evdev->dev);

  	evdev->handle.handler = handler;
  	evdev->handle.private = evdev;

  	evdev->dev.devt = MKDEV(INPUT_MAJOR, EVDEV_MINOR_BASE + minor);

  	evdev->dev.class = &input_class;
  	evdev->dev.parent = &dev->dev;

  	evdev->dev.release = evdev_free;
  	device_initialize(&evdev->dev);

  	error = input_register_handle(&evdev->handle);

  	if (error)

  		goto err_free_evdev;

  	error = evdev_install_chrdev(evdev);
  	if (error)
  		goto err_unregister_handle;
  
  	error = device_add(&evdev->dev);

  	if (error)

  		goto err_cleanup_evdev;

  	return 0;

   err_cleanup_evdev:
  	evdev_cleanup(evdev);
   err_unregister_handle:
  	input_unregister_handle(&evdev->handle);

   err_free_evdev:

  	put_device(&evdev->dev);

  	return error;

  }
  
  static void evdev_disconnect(struct input_handle *handle)
  {
  	struct evdev *evdev = handle->private;

  	device_del(&evdev->dev);

  	evdev_cleanup(evdev);
  	input_unregister_handle(handle);

  	put_device(&evdev->dev);

  }

  static const struct input_device_id evdev_ids[] = {

  	{ .driver_info = 1 },	/* Matches all devices */
  	{ },			/* Terminating zero entry */
  };
  
  MODULE_DEVICE_TABLE(input, evdev_ids);
  
  static struct input_handler evdev_handler = {

  	.event		= evdev_event,
  	.connect	= evdev_connect,
  	.disconnect	= evdev_disconnect,
  	.fops		= &evdev_fops,
  	.minor		= EVDEV_MINOR_BASE,
  	.name		= "evdev",
  	.id_table	= evdev_ids,

  };
  
  static int __init evdev_init(void)
  {

  	return input_register_handler(&evdev_handler);

  }
  
  static void __exit evdev_exit(void)
  {
  	input_unregister_handler(&evdev_handler);
  }
  
  module_init(evdev_init);
  module_exit(evdev_exit);
  
  MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
  MODULE_DESCRIPTION("Input driver event char devices");
  MODULE_LICENSE("GPL");