linux/drivers/input/joydev.c

/*
 * Joystick device driver for the input driver suite.
 *
 * Copyright (c) 1999-2002 Vojtech Pavlik
 * Copyright (c) 1999 Colin Van Dyke
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

#include <asm/io.h>
#include <asm/system.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/joystick.h>
#include <linux/input.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/device.h>

MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
MODULE_DESCRIPTION("Joystick device interfaces");
MODULE_SUPPORTED_DEVICE("input/js");
MODULE_LICENSE("GPL");

#define JOYDEV_MINOR_BASE	0
#define JOYDEV_MINORS		16
#define JOYDEV_BUFFER_SIZE	64

struct joydev {
	int exist;
	int open;
	int minor;
	struct input_handle handle;
	wait_queue_head_t wait;
	struct list_head client_list;
	spinlock_t client_lock; /* protects client_list */
	struct mutex mutex;
	struct device dev;

	struct js_corr corr[ABS_MAX + 1];
	struct JS_DATA_SAVE_TYPE glue;
	int nabs;
	int nkey;
	__u16 keymap[KEY_MAX - BTN_MISC + 1];
	__u16 keypam[KEY_MAX - BTN_MISC + 1];
	__u8 absmap[ABS_MAX + 1];
	__u8 abspam[ABS_MAX + 1];
	__s16 abs[ABS_MAX + 1];
};

struct joydev_client {
	struct js_event buffer[JOYDEV_BUFFER_SIZE];
	int head;
	int tail;
	int startup;
	spinlock_t buffer_lock; /* protects access to buffer, head and tail */
	struct fasync_struct *fasync;
	struct joydev *joydev;
	struct list_head node;
};

static struct joydev *joydev_table[JOYDEV_MINORS];
static DEFINE_MUTEX(joydev_table_mutex);

static int joydev_correct(int value, struct js_corr *corr)
{
	switch (corr->type) {

	case JS_CORR_NONE:
		break;

	case JS_CORR_BROKEN:
		value = value > corr->coef[0] ? (value < corr->coef[1] ? 0 :
			((corr->coef[3] * (value - corr->coef[1])) >> 14)) :
			((corr->coef[2] * (value - corr->coef[0])) >> 14);
		break;

	default:
		return 0;
	}

	return value < -32767 ? -32767 : (value > 32767 ? 32767 : value);
}

static void joydev_pass_event(struct joydev_client *client,
			      struct js_event *event)
{
	struct joydev *joydev = client->joydev;

	/*
	 * IRQs already disabled, just acquire the lock
	 */
	spin_lock(&client->buffer_lock);

	client->buffer[client->head] = *event;

	if (client->startup == joydev->nabs + joydev->nkey) {
		client->head++;
		client->head &= JOYDEV_BUFFER_SIZE - 1;
		if (client->tail == client->head)
			client->startup = 0;
	}

	spin_unlock(&client->buffer_lock);

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

static void joydev_event(struct input_handle *handle,
			 unsigned int type, unsigned int code, int value)
{
	struct joydev *joydev = handle->private;
	struct joydev_client *client;
	struct js_event event;

	switch (type) {

	case EV_KEY:
		if (code < BTN_MISC || value == 2)
			return;
		event.type = JS_EVENT_BUTTON;
		event.number = joydev->keymap[code - BTN_MISC];
		event.value = value;
		break;

	case EV_ABS:
		event.type = JS_EVENT_AXIS;
		event.number = joydev->absmap[code];
		event.value = joydev_correct(value,
					&joydev->corr[event.number]);
		if (event.value == joydev->abs[event.number])
			return;
		joydev->abs[event.number] = event.value;
		break;

	default:
		return;
	}

	event.time = jiffies_to_msecs(jiffies);

	rcu_read_lock();
	list_for_each_entry_rcu(client, &joydev->client_list, node)
		joydev_pass_event(client, &event);
	rcu_read_unlock();

	wake_up_interruptible(&joydev->wait);
}

static int joydev_fasync(int fd, struct file *file, int on)
{
	struct joydev_client *client = file->private_data;

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

static void joydev_free(struct device *dev)
{
	struct joydev *joydev = container_of(dev, struct joydev, dev);

	input_put_device(joydev->handle.dev);
	kfree(joydev);
}

static void joydev_attach_client(struct joydev *joydev,
				 struct joydev_client *client)
{
	spin_lock(&joydev->client_lock);
	list_add_tail_rcu(&client->node, &joydev->client_list);
	spin_unlock(&joydev->client_lock);
	synchronize_rcu();
}

static void joydev_detach_client(struct joydev *joydev,
				 struct joydev_client *client)
{
	spin_lock(&joydev->client_lock);
	list_del_rcu(&client->node);
	spin_unlock(&joydev->client_lock);
	synchronize_rcu();
}

static int joydev_open_device(struct joydev *joydev)
{
	int retval;

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

	if (!joydev->exist)
		retval = -ENODEV;
	else if (!joydev->open++) {
		retval = input_open_device(&joydev->handle);
		if (retval)
			joydev->open--;
	}

	mutex_unlock(&joydev->mutex);
	return retval;
}

static void joydev_close_device(struct joydev *joydev)
{
	mutex_lock(&joydev->mutex);

	if (joydev->exist && !--joydev->open)
		input_close_device(&joydev->handle);

	mutex_unlock(&joydev->mutex);
}

/*
 * Wake up users waiting for IO so they can disconnect from
 * dead device.
 */
static void joydev_hangup(struct joydev *joydev)
{
	struct joydev_client *client;

	spin_lock(&joydev->client_lock);
	list_for_each_entry(client, &joydev->client_list, node)
		kill_fasync(&client->fasync, SIGIO, POLL_HUP);
	spin_unlock(&joydev->client_lock);

	wake_up_interruptible(&joydev->wait);
}

static int joydev_release(struct inode *inode, struct file *file)
{
	struct joydev_client *client = file->private_data;
	struct joydev *joydev = client->joydev;

	joydev_detach_client(joydev, client);
	kfree(client);

	joydev_close_device(joydev);
	put_device(&joydev->dev);

	return 0;
}

static int joydev_open(struct inode *inode, struct file *file)
{
	struct joydev_client *client;
	struct joydev *joydev;
	int i = iminor(inode) - JOYDEV_MINOR_BASE;
	int error;

	if (i >= JOYDEV_MINORS)
		return -ENODEV;

	error = mutex_lock_interruptible(&joydev_table_mutex);
	if (error)
		return error;
	joydev = joydev_table[i];
	if (joydev)
		get_device(&joydev->dev);
	mutex_unlock(&joydev_table_mutex);

	if (!joydev)
		return -ENODEV;

	client = kzalloc(sizeof(struct joydev_client), GFP_KERNEL);
	if (!client) {
		error = -ENOMEM;
		goto err_put_joydev;
	}

	spin_lock_init(&client->buffer_lock);
	client->joydev = joydev;
	joydev_attach_client(joydev, client);

	error = joydev_open_device(joydev);
	if (error)
		goto err_free_client;

	file->private_data = client;
	return 0;

 err_free_client:
	joydev_detach_client(joydev, client);
	kfree(client);
 err_put_joydev:
	put_device(&joydev->dev);
	return error;
}

static int joydev_generate_startup_event(struct joydev_client *client,
					 struct input_dev *input,
					 struct js_event *event)
{
	struct joydev *joydev = client->joydev;
	int have_event;

	spin_lock_irq(&client->buffer_lock);

	have_event = client->startup < joydev->nabs + joydev->nkey;

	if (have_event) {

		event->time = jiffies_to_msecs(jiffies);
		if (client->startup < joydev->nkey) {
			event->type = JS_EVENT_BUTTON | JS_EVENT_INIT;
			event->number = client->startup;
			event->value = !!test_bit(joydev->keypam[event->number],
						  input->key);
		} else {
			event->type = JS_EVENT_AXIS | JS_EVENT_INIT;
			event->number = client->startup - joydev->nkey;
			event->value = joydev->abs[event->number];
		}
		client->startup++;
	}

	spin_unlock_irq(&client->buffer_lock);

	return have_event;
}

static int joydev_fetch_next_event(struct joydev_client *client,
				   struct js_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 &= JOYDEV_BUFFER_SIZE - 1;
	}

	spin_unlock_irq(&client->buffer_lock);

	return have_event;
}

/*
 * Old joystick interface
 */
static ssize_t joydev_0x_read(struct joydev_client *client,
			      struct input_dev *input,
			      char __user *buf)
{
	struct joydev *joydev = client->joydev;
	struct JS_DATA_TYPE data;
	int i;

	spin_lock_irq(&input->event_lock);

	/*
	 * Get device state
	 */
	for (data.buttons = i = 0; i < 32 && i < joydev->nkey; i++)
		data.buttons |=
			test_bit(joydev->keypam[i], input->key) ? (1 << i) : 0;
	data.x = (joydev->abs[0] / 256 + 128) >> joydev->glue.JS_CORR.x;
	data.y = (joydev->abs[1] / 256 + 128) >> joydev->glue.JS_CORR.y;

	/*
	 * Reset reader's event queue
	 */
	spin_lock(&client->buffer_lock);
	client->startup = 0;
	client->tail = client->head;
	spin_unlock(&client->buffer_lock);

	spin_unlock_irq(&input->event_lock);

	if (copy_to_user(buf, &data, sizeof(struct JS_DATA_TYPE)))
		return -EFAULT;

	return sizeof(struct JS_DATA_TYPE);
}

static inline int joydev_data_pending(struct joydev_client *client)
{
	struct joydev *joydev = client->joydev;

	return client->startup < joydev->nabs + joydev->nkey ||
		client->head != client->tail;
}

static ssize_t joydev_read(struct file *file, char __user *buf,
			   size_t count, loff_t *ppos)
{
	struct joydev_client *client = file->private_data;
	struct joydev *joydev = client->joydev;
	struct input_dev *input = joydev->handle.dev;
	struct js_event event;
	int retval;

	if (!joydev->exist)
		return -ENODEV;

	if (count < sizeof(struct js_event))
		return -EINVAL;

	if (count == sizeof(struct JS_DATA_TYPE))
		return joydev_0x_read(client, input, buf);

	if (!joydev_data_pending(client) && (file->f_flags & O_NONBLOCK))
		return -EAGAIN;

	retval = wait_event_interruptible(joydev->wait,
			!joydev->exist || joydev_data_pending(client));
	if (retval)
		return retval;

	if (!joydev->exist)
		return -ENODEV;

	while (retval + sizeof(struct js_event) <= count &&
	       joydev_generate_startup_event(client, input, &event)) {

		if (copy_to_user(buf + retval, &event, sizeof(struct js_event)))
			return -EFAULT;

		retval += sizeof(struct js_event);
	}

	while (retval + sizeof(struct js_event) <= count &&
	       joydev_fetch_next_event(client, &event)) {

		if (copy_to_user(buf + retval, &event, sizeof(struct js_event)))
			return -EFAULT;

		retval += sizeof(struct js_event);
	}

	return retval;
}

/* No kernel lock - fine */
static unsigned int joydev_poll(struct file *file, poll_table *wait)
{
	struct joydev_client *client = file->private_data;
	struct joydev *joydev = client->joydev;

	poll_wait(file, &joydev->wait, wait);
	return (joydev_data_pending(client) ? (POLLIN | POLLRDNORM) : 0) |
		(joydev->exist ?  0 : (POLLHUP | POLLERR));
}

static int joydev_handle_JSIOCSAXMAP(struct joydev *joydev,
				     void __user *argp, size_t len)
{
	__u8 *abspam;
	int i;
	int retval = 0;

	len = min(len, sizeof(joydev->abspam));

	/* Validate the map. */
	abspam = kmalloc(len, GFP_KERNEL);
	if (!abspam)
		return -ENOMEM;

	if (copy_from_user(abspam, argp, len)) {
		retval = -EFAULT;
		goto out;
	}

	for (i = 0; i < joydev->nabs; i++) {
		if (abspam[i] > ABS_MAX) {
			retval = -EINVAL;
			goto out;
		}
	}

	memcpy(joydev->abspam, abspam, len);

 out:
	kfree(abspam);
	return retval;
}

static int joydev_handle_JSIOCSBTNMAP(struct joydev *joydev,
				      void __user *argp, size_t len)
{
	__u16 *keypam;
	int i;
	int retval = 0;

	len = min(len, sizeof(joydev->keypam));

	/* Validate the map. */
	keypam = kmalloc(len, GFP_KERNEL);
	if (!keypam)
		return -ENOMEM;

	if (copy_from_user(keypam, argp, len)) {
		retval = -EFAULT;
		goto out;
	}

	for (i = 0; i < joydev->nkey; i++) {
		if (keypam[i] > KEY_MAX || keypam[i] < BTN_MISC) {
			retval = -EINVAL;
			goto out;
		}
	}

	memcpy(joydev->keypam, keypam, len);

	for (i = 0; i < joydev->nkey; i++)
		joydev->keymap[keypam[i] - BTN_MISC] = i;

 out:
	kfree(keypam);
	return retval;
}


static int joydev_ioctl_common(struct joydev *joydev,
				unsigned int cmd, void __user *argp)
{
	struct input_dev *dev = joydev->handle.dev;
	size_t len;
	int i, j;
	const char *name;

	/* Process fixed-sized commands. */
	switch (cmd) {

	case JS_SET_CAL:
		return copy_from_user(&joydev->glue.JS_CORR, argp,
				sizeof(joydev->glue.JS_CORR)) ? -EFAULT : 0;

	case JS_GET_CAL:
		return copy_to_user(argp, &joydev->glue.JS_CORR,
				sizeof(joydev->glue.JS_CORR)) ? -EFAULT : 0;

	case JS_SET_TIMEOUT:
		return get_user(joydev->glue.JS_TIMEOUT, (s32 __user *) argp);

	case JS_GET_TIMEOUT:
		return put_user(joydev->glue.JS_TIMEOUT, (s32 __user *) argp);

	case JSIOCGVERSION:
		return put_user(JS_VERSION, (__u32 __user *) argp);

	case JSIOCGAXES:
		return put_user(joydev->nabs, (__u8 __user *) argp);

	case JSIOCGBUTTONS:
		return put_user(joydev->nkey, (__u8 __user *) argp);

	case JSIOCSCORR:
		if (copy_from_user(joydev->corr, argp,
			      sizeof(joydev->corr[0]) * joydev->nabs))
		    return -EFAULT;

		for (i = 0; i < joydev->nabs; i++) {
			j = joydev->abspam[i];
			joydev->abs[i] = joydev_correct(dev->abs[j],
							&joydev->corr[i]);
		}
		return 0;

	case JSIOCGCORR:
		return copy_to_user(argp, joydev->corr,
			sizeof(joydev->corr[0]) * joydev->nabs) ? -EFAULT : 0;

	}

	/*
	 * Process variable-sized commands (the axis and button map commands
	 * are considered variable-sized to decouple them from the values of
	 * ABS_MAX and KEY_MAX).
	 */
	switch (cmd & ~IOCSIZE_MASK) {

	case (JSIOCSAXMAP & ~IOCSIZE_MASK):
		return joydev_handle_JSIOCSAXMAP(joydev, argp, _IOC_SIZE(cmd));

	case (JSIOCGAXMAP & ~IOCSIZE_MASK):
		len = min_t(size_t, _IOC_SIZE(cmd), sizeof(joydev->abspam));
		return copy_to_user(argp, joydev->abspam, len) ? -EFAULT : len;

	case (JSIOCSBTNMAP & ~IOCSIZE_MASK):
		return joydev_handle_JSIOCSBTNMAP(joydev, argp, _IOC_SIZE(cmd));

	case (JSIOCGBTNMAP & ~IOCSIZE_MASK):
		len = min_t(size_t, _IOC_SIZE(cmd), sizeof(joydev->keypam));
		return copy_to_user(argp, joydev->keypam, len) ? -EFAULT : len;

	case JSIOCGNAME(0):
		name = dev->name;
		if (!name)
			return 0;

		len = min_t(size_t, _IOC_SIZE(cmd), strlen(name) + 1);
		return copy_to_user(argp, name, len) ? -EFAULT : len;
	}

	return -EINVAL;
}

#ifdef CONFIG_COMPAT
static long joydev_compat_ioctl(struct file *file,
				unsigned int cmd, unsigned long arg)
{
	struct joydev_client *client = file->private_data;
	struct joydev *joydev = client->joydev;
	void __user *argp = (void __user *)arg;
	s32 tmp32;
	struct JS_DATA_SAVE_TYPE_32 ds32;
	int retval;

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

	if (!joydev->exist) {
		retval = -ENODEV;
		goto out;
	}

	switch (cmd) {

	case JS_SET_TIMELIMIT:
		retval = get_user(tmp32, (s32 __user *) arg);
		if (retval == 0)
			joydev->glue.JS_TIMELIMIT = tmp32;
		break;

	case JS_GET_TIMELIMIT:
		tmp32 = joydev->glue.JS_TIMELIMIT;
		retval = put_user(tmp32, (s32 __user *) arg);
		break;

	case JS_SET_ALL:
		retval = copy_from_user(&ds32, argp,
					sizeof(ds32)) ? -EFAULT : 0;
		if (retval == 0) {
			joydev->glue.JS_TIMEOUT    = ds32.JS_TIMEOUT;
			joydev->glue.BUSY          = ds32.BUSY;
			joydev->glue.JS_EXPIRETIME = ds32.JS_EXPIRETIME;
			joydev->glue.JS_TIMELIMIT  = ds32.JS_TIMELIMIT;
			joydev->glue.JS_SAVE       = ds32.JS_SAVE;
			joydev->glue.JS_CORR       = ds32.JS_CORR;
		}
		break;

	case JS_GET_ALL:
		ds32.JS_TIMEOUT    = joydev->glue.JS_TIMEOUT;
		ds32.BUSY          = joydev->glue.BUSY;
		ds32.JS_EXPIRETIME = joydev->glue.JS_EXPIRETIME;
		ds32.JS_TIMELIMIT  = joydev->glue.JS_TIMELIMIT;
		ds32.JS_SAVE       = joydev->glue.JS_SAVE;
		ds32.JS_CORR       = joydev->glue.JS_CORR;

		retval = copy_to_user(argp, &ds32, sizeof(ds32)) ? -EFAULT : 0;
		break;

	default:
		retval = joydev_ioctl_common(joydev, cmd, argp);
		break;
	}

 out:
	mutex_unlock(&joydev->mutex);
	return retval;
}
#endif /* CONFIG_COMPAT */

static long joydev_ioctl(struct file *file,
			 unsigned int cmd, unsigned long arg)
{
	struct joydev_client *client = file->private_data;
	struct joydev *joydev = client->joydev;
	void __user *argp = (void __user *)arg;
	int retval;

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

	if (!joydev->exist) {
		retval = -ENODEV;
		goto out;
	}

	switch (cmd) {

	case JS_SET_TIMELIMIT:
		retval = get_user(joydev->glue.JS_TIMELIMIT,
				  (long __user *) arg);
		break;

	case JS_GET_TIMELIMIT:
		retval = put_user(joydev->glue.JS_TIMELIMIT,
				  (long __user *) arg);
		break;

	case JS_SET_ALL:
		retval = copy_from_user(&joydev->glue, argp,
					sizeof(joydev->glue)) ? -EFAULT: 0;
		break;

	case JS_GET_ALL:
		retval = copy_to_user(argp, &joydev->glue,
				      sizeof(joydev->glue)) ? -EFAULT : 0;
		break;

	default:
		retval = joydev_ioctl_common(joydev, cmd, argp);
		break;
	}
 out:
	mutex_unlock(&joydev->mutex);
	return retval;
}

static const struct file_operations joydev_fops = {
	.owner		= THIS_MODULE,
	.read		= joydev_read,
	.poll		= joydev_poll,
	.open		= joydev_open,
	.release	= joydev_release,
	.unlocked_ioctl	= joydev_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl	= joydev_compat_ioctl,
#endif
	.fasync		= joydev_fasync,
};

static int joydev_install_chrdev(struct joydev *joydev)
{
	joydev_table[joydev->minor] = joydev;
	return 0;
}

static void joydev_remove_chrdev(struct joydev *joydev)
{
	mutex_lock(&joydev_table_mutex);
	joydev_table[joydev->minor] = NULL;
	mutex_unlock(&joydev_table_mutex);
}

/*
 * Mark device non-existant. 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 joydev_mark_dead(struct joydev *joydev)
{
	mutex_lock(&joydev->mutex);
	joydev->exist = 0;
	mutex_unlock(&joydev->mutex);
}

static void joydev_cleanup(struct joydev *joydev)
{
	struct input_handle *handle = &joydev->handle;

	joydev_mark_dead(joydev);
	joydev_hangup(joydev);
	joydev_remove_chrdev(joydev);

	/* joydev is marked dead so noone else accesses joydev->open */
	if (joydev->open)
		input_close_device(handle);
}

static int joydev_connect(struct input_handler *handler, struct input_dev *dev,
			  const struct input_device_id *id)
{
	struct joydev *joydev;
	int i, j, t, minor;
	int error;

	for (minor = 0; minor < JOYDEV_MINORS; minor++)
		if (!joydev_table[minor])
			break;

	if (minor == JOYDEV_MINORS) {
		printk(KERN_ERR "joydev: no more free joydev devices\n");
		return -ENFILE;
	}

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

	INIT_LIST_HEAD(&joydev->client_list);
	spin_lock_init(&joydev->client_lock);
	mutex_init(&joydev->mutex);
	init_waitqueue_head(&joydev->wait);

	dev_set_name(&joydev->dev, "js%d", minor);
	joydev->exist = 1;
	joydev->minor = minor;

	joydev->exist = 1;
	joydev->handle.dev = input_get_device(dev);
	joydev->handle.name = dev_name(&joydev->dev);
	joydev->handle.handler = handler;
	joydev->handle.private = joydev;

	for (i = 0; i < ABS_MAX + 1; i++)
		if (test_bit(i, dev->absbit)) {
			joydev->absmap[i] = joydev->nabs;
			joydev->abspam[joydev->nabs] = i;
			joydev->nabs++;
		}

	for (i = BTN_JOYSTICK - BTN_MISC; i < KEY_MAX - BTN_MISC + 1; i++)
		if (test_bit(i + BTN_MISC, dev->keybit)) {
			joydev->keymap[i] = joydev->nkey;
			joydev->keypam[joydev->nkey] = i + BTN_MISC;
			joydev->nkey++;
		}

	for (i = 0; i < BTN_JOYSTICK - BTN_MISC; i++)
		if (test_bit(i + BTN_MISC, dev->keybit)) {
			joydev->keymap[i] = joydev->nkey;
			joydev->keypam[joydev->nkey] = i + BTN_MISC;
			joydev->nkey++;
		}

	for (i = 0; i < joydev->nabs; i++) {
		j = joydev->abspam[i];
		if (dev->absmax[j] == dev->absmin[j]) {
			joydev->corr[i].type = JS_CORR_NONE;
			joydev->abs[i] = dev->abs[j];
			continue;
		}
		joydev->corr[i].type = JS_CORR_BROKEN;
		joydev->corr[i].prec = dev->absfuzz[j];
		joydev->corr[i].coef[0] =
			(dev->absmax[j] + dev->absmin[j]) / 2 - dev->absflat[j];
		joydev->corr[i].coef[1] =
			(dev->absmax[j] + dev->absmin[j]) / 2 + dev->absflat[j];

		t = (dev->absmax[j] - dev->absmin[j]) / 2 - 2 * dev->absflat[j];
		if (t) {
			joydev->corr[i].coef[2] = (1 << 29) / t;
			joydev->corr[i].coef[3] = (1 << 29) / t;

			joydev->abs[i] = joydev_correct(dev->abs[j],
							joydev->corr + i);
		}
	}

	joydev->dev.devt = MKDEV(INPUT_MAJOR, JOYDEV_MINOR_BASE + minor);
	joydev->dev.class = &input_class;
	joydev->dev.parent = &dev->dev;
	joydev->dev.release = joydev_free;
	device_initialize(&joydev->dev);

	error = input_register_handle(&joydev->handle);
	if (error)
		goto err_free_joydev;

	error = joydev_install_chrdev(joydev);
	if (error)
		goto err_unregister_handle;

	error = device_add(&joydev->dev);
	if (error)
		goto err_cleanup_joydev;

	return 0;

 err_cleanup_joydev:
	joydev_cleanup(joydev);
 err_unregister_handle:
	input_unregister_handle(&joydev->handle);
 err_free_joydev:
	put_device(&joydev->dev);
	return error;
}

static void joydev_disconnect(struct input_handle *handle)
{
	struct joydev *joydev = handle->private;

	device_del(&joydev->dev);
	joydev_cleanup(joydev);
	input_unregister_handle(handle);
	put_device(&joydev->dev);
}

static const struct input_device_id joydev_blacklist[] = {
	{
		.flags = INPUT_DEVICE_ID_MATCH_EVBIT |
				INPUT_DEVICE_ID_MATCH_KEYBIT,
		.evbit = { BIT_MASK(EV_KEY) },
		.keybit = { [BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH) },
	},	/* Avoid itouchpads and touchscreens */
	{
		.flags = INPUT_DEVICE_ID_MATCH_EVBIT |
				INPUT_DEVICE_ID_MATCH_KEYBIT,
		.evbit = { BIT_MASK(EV_KEY) },
		.keybit = { [BIT_WORD(BTN_DIGI)] = BIT_MASK(BTN_DIGI) },
	},	/* Avoid tablets, digitisers and similar devices */
	{ }	/* Terminating entry */
};

static const struct input_device_id joydev_ids[] = {
	{
		.flags = INPUT_DEVICE_ID_MATCH_EVBIT |
				INPUT_DEVICE_ID_MATCH_ABSBIT,
		.evbit = { BIT_MASK(EV_ABS) },
		.absbit = { BIT_MASK(ABS_X) },
	},
	{
		.flags = INPUT_DEVICE_ID_MATCH_EVBIT |
				INPUT_DEVICE_ID_MATCH_ABSBIT,
		.evbit = { BIT_MASK(EV_ABS) },
		.absbit = { BIT_MASK(ABS_WHEEL) },
	},
	{
		.flags = INPUT_DEVICE_ID_MATCH_EVBIT |
				INPUT_DEVICE_ID_MATCH_ABSBIT,
		.evbit = { BIT_MASK(EV_ABS) },
		.absbit = { BIT_MASK(ABS_THROTTLE) },
	},
	{ }	/* Terminating entry */
};

MODULE_DEVICE_TABLE(input, joydev_ids);

static struct input_handler joydev_handler = {
	.event		= joydev_event,
	.connect	= joydev_connect,
	.disconnect	= joydev_disconnect,
	.fops		= &joydev_fops,
	.minor		= JOYDEV_MINOR_BASE,
	.name		= "joydev",
	.id_table	= joydev_ids,
	.blacklist	= joydev_blacklist,
};

static int __init joydev_init(void)
{
	return input_register_handler(&joydev_handler);
}

static void __exit joydev_exit(void)
{
	input_unregister_handler(&joydev_handler);
}

module_init(joydev_init);
module_exit(joydev_exit);