joydev.c

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/*
 * 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.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <asm/io.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/sched.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>
#include <linux/cdev.h>

MODULE_AUTHOR("Vojtech Pavlik <[email protected]>");
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 open;
    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 cdev cdev;
    bool exist;

    struct js_corr corr[ABS_CNT];
    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_CNT];
    __u8 abspam[ABS_CNT];
    __s16 abs[ABS_CNT];
};

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 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);
}

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);

    return 0;
}

static int joydev_open(struct inode *inode, struct file *file)
{
    struct joydev *joydev =
            container_of(inode->i_cdev, struct joydev, cdev);
    struct joydev_client *client;
    int error;

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

    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;
    nonseekable_open(inode, file);

    return 0;

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

    for (i = 0; i < joydev->nabs; i++)
        joydev->absmap[joydev->abspam[i]] = i;

 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;
    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++) {
            int val = input_abs_get_val(dev, joydev->abspam[i]);
            joydev->abs[i] = joydev_correct(val, &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,
    .llseek     = no_llseek,
};

/*
 * 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 joydev_mark_dead(struct joydev *joydev)
{
    mutex_lock(&joydev->mutex);
    joydev->exist = false;
    mutex_unlock(&joydev->mutex);
}

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

    joydev_mark_dead(joydev);
    joydev_hangup(joydev);

    cdev_del(&joydev->cdev);

    /* joydev is marked dead so no one else accesses joydev->open */
    if (joydev->open)
        input_close_device(handle);
}


static bool joydev_match(struct input_handler *handler, struct input_dev *dev)
{
    /* Avoid touchpads and touchscreens */
    if (test_bit(EV_KEY, dev->evbit) && test_bit(BTN_TOUCH, dev->keybit))
        return false;

    /* Avoid tablets, digitisers and similar devices */
    if (test_bit(EV_KEY, dev->evbit) && test_bit(BTN_DIGI, dev->keybit))
        return false;

    return true;
}

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, dev_no;
    int error;

    minor = input_get_new_minor(JOYDEV_MINOR_BASE, JOYDEV_MINORS, true);
    if (minor < 0) {
        error = minor;
        pr_err("failed to reserve new minor: %d\n", error);
        return error;
    }

    joydev = kzalloc(sizeof(struct joydev), GFP_KERNEL);
    if (!joydev) {
        error = -ENOMEM;
        goto err_free_minor;
    }

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

    dev_no = minor;
    /* Normalize device number if it falls into legacy range */
    if (dev_no < JOYDEV_MINOR_BASE + JOYDEV_MINORS)
        dev_no -= JOYDEV_MINOR_BASE;
    dev_set_name(&joydev->dev, "js%d", dev_no);

    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_CNT; 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 (input_abs_get_max(dev, j) == input_abs_get_min(dev, j)) {
            joydev->corr[i].type = JS_CORR_NONE;
            joydev->abs[i] = input_abs_get_val(dev, j);
            continue;
        }
        joydev->corr[i].type = JS_CORR_BROKEN;
        joydev->corr[i].prec = input_abs_get_fuzz(dev, j);

        t = (input_abs_get_max(dev, j) + input_abs_get_min(dev, j)) / 2;
        joydev->corr[i].coef[0] = t - input_abs_get_flat(dev, j);
        joydev->corr[i].coef[1] = t + input_abs_get_flat(dev, j);

        t = (input_abs_get_max(dev, j) - input_abs_get_min(dev, j)) / 2
            - 2 * input_abs_get_flat(dev, j);
        if (t) {
            joydev->corr[i].coef[2] = (1 << 29) / t;
            joydev->corr[i].coef[3] = (1 << 29) / t;

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

    joydev->dev.devt = MKDEV(INPUT_MAJOR, 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;

    cdev_init(&joydev->cdev, &joydev_fops);
    joydev->cdev.kobj.parent = &joydev->dev.kobj;
    error = cdev_add(&joydev->cdev, joydev->dev.devt, 1);
    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);
 err_free_minor:
    input_free_minor(minor);
    return error;
}

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

    device_del(&joydev->dev);
    joydev_cleanup(joydev);
    input_free_minor(MINOR(joydev->dev.devt));
    input_unregister_handle(handle);
    put_device(&joydev->dev);
}

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) },
    },
    {
        .flags = INPUT_DEVICE_ID_MATCH_EVBIT |
                INPUT_DEVICE_ID_MATCH_KEYBIT,
        .evbit = { BIT_MASK(EV_KEY) },
        .keybit = {[BIT_WORD(BTN_JOYSTICK)] = BIT_MASK(BTN_JOYSTICK) },
    },
    {
        .flags = INPUT_DEVICE_ID_MATCH_EVBIT |
                INPUT_DEVICE_ID_MATCH_KEYBIT,
        .evbit = { BIT_MASK(EV_KEY) },
        .keybit = { [BIT_WORD(BTN_GAMEPAD)] = BIT_MASK(BTN_GAMEPAD) },
    },
    {
        .flags = INPUT_DEVICE_ID_MATCH_EVBIT |
                INPUT_DEVICE_ID_MATCH_KEYBIT,
        .evbit = { BIT_MASK(EV_KEY) },
        .keybit = { [BIT_WORD(BTN_TRIGGER_HAPPY)] = BIT_MASK(BTN_TRIGGER_HAPPY) },
    },
    { } /* Terminating entry */
};

MODULE_DEVICE_TABLE(input, joydev_ids);

static struct input_handler joydev_handler = {
    .event      = joydev_event,
    .match      = joydev_match,
    .connect    = joydev_connect,
    .disconnect = joydev_disconnect,
    .legacy_minors  = true,
    .minor      = JOYDEV_MINOR_BASE,
    .name       = "joydev",
    .id_table   = joydev_ids,
};

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);