// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Joystick device driver for the input driver suite.
 *
 * Copyright (c) 1999-2002 Vojtech Pavlik
 * Copyright (c) 1999 Colin Van Dyke
 */

#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/module.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/cdev.h>

MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
MODULE_DESCRIPTION("Joystick device interfaces");
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 clamp(value, -32767, 32767);
}

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 void joydev_refresh_state(struct joydev *joydev)
{
        struct input_dev *dev = joydev->handle.dev;
        int i, val;

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

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--;
                else
                        joydev_refresh_state(joydev);
        }

        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;
        stream_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 __poll_t 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) ? (EPOLLIN | EPOLLRDNORM) : 0) |
                (joydev->exist ?  0 : (EPOLLHUP | EPOLLERR));
}

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 = memdup_user(argp, len);
        if (IS_ERR(abspam))
                return PTR_ERR(abspam);

        for (i = 0; i < len && 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;

        if (len % sizeof(*keypam))
                return -EINVAL;

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

        /* Validate the map. */
        keypam = memdup_user(argp, len);
        if (IS_ERR(keypam))
                return PTR_ERR(keypam);

        for (i = 0; i < (len / 2) && 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[joydev->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);

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

/*
 * These codes are copied from from hid-ids.h, unfortunately there is no common
 * usb_ids/bt_ids.h header.
 */
#define USB_VENDOR_ID_SONY                      0x054c
#define USB_DEVICE_ID_SONY_PS3_CONTROLLER               0x0268
#define USB_DEVICE_ID_SONY_PS4_CONTROLLER               0x05c4
#define USB_DEVICE_ID_SONY_PS4_CONTROLLER_2             0x09cc
#define USB_DEVICE_ID_SONY_PS4_CONTROLLER_DONGLE        0x0ba0

#define USB_VENDOR_ID_THQ                       0x20d6
#define USB_DEVICE_ID_THQ_PS3_UDRAW                     0xcb17

#define ACCEL_DEV(vnd, prd)                                             \
        {                                                               \
                .flags = INPUT_DEVICE_ID_MATCH_VENDOR |                 \
                                INPUT_DEVICE_ID_MATCH_PRODUCT |         \
                                INPUT_DEVICE_ID_MATCH_PROPBIT,          \
                .vendor = (vnd),                                        \
                .product = (prd),                                       \
                .propbit = { BIT_MASK(INPUT_PROP_ACCELEROMETER) },      \
        }

static const struct input_device_id joydev_blacklist[] = {
        /* Avoid touchpads and touchscreens */
        {
                .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 tablets, digitisers and similar devices */
        {
                .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) },
        },
        /* Disable accelerometers on composite devices */
        ACCEL_DEV(USB_VENDOR_ID_SONY, USB_DEVICE_ID_SONY_PS3_CONTROLLER),
        ACCEL_DEV(USB_VENDOR_ID_SONY, USB_DEVICE_ID_SONY_PS4_CONTROLLER),
        ACCEL_DEV(USB_VENDOR_ID_SONY, USB_DEVICE_ID_SONY_PS4_CONTROLLER_2),
        ACCEL_DEV(USB_VENDOR_ID_SONY, USB_DEVICE_ID_SONY_PS4_CONTROLLER_DONGLE),
        ACCEL_DEV(USB_VENDOR_ID_THQ, USB_DEVICE_ID_THQ_PS3_UDRAW),
        { /* sentinel */ }
};

static bool joydev_dev_is_blacklisted(struct input_dev *dev)
{
        const struct input_device_id *id;

        for (id = joydev_blacklist; id->flags; id++) {
                if (input_match_device_id(dev, id)) {
                        dev_dbg(&dev->dev,
                                "joydev: blacklisting '%s'\n", dev->name);
                        return true;
                }
        }

        return false;
}

static bool joydev_dev_is_absolute_mouse(struct input_dev *dev)
{
        DECLARE_BITMAP(jd_scratch, KEY_CNT);
        bool ev_match = false;

        BUILD_BUG_ON(ABS_CNT > KEY_CNT || EV_CNT > KEY_CNT);

        /*
         * Virtualization (VMware, etc) and remote management (HP
         * ILO2) solutions use absolute coordinates for their virtual
         * pointing devices so that there is one-to-one relationship
         * between pointer position on the host screen and virtual
         * guest screen, and so their mice use ABS_X, ABS_Y and 3
         * primary button events. This clashes with what joydev
         * considers to be joysticks (a device with at minimum ABS_X
         * axis).
         *
         * Here we are trying to separate absolute mice from
         * joysticks. A device is, for joystick detection purposes,
         * considered to be an absolute mouse if the following is
         * true:
         *
         * 1) Event types are exactly
         *      EV_ABS, EV_KEY and EV_SYN
         *    or
         *      EV_ABS, EV_KEY, EV_SYN and EV_MSC
         *    or
         *      EV_ABS, EV_KEY, EV_SYN, EV_MSC and EV_REL.
         * 2) Absolute events are exactly ABS_X and ABS_Y.
         * 3) Keys are exactly BTN_LEFT, BTN_RIGHT and BTN_MIDDLE.
         * 4) Device is not on "Amiga" bus.
         */

        bitmap_zero(jd_scratch, EV_CNT);
        /* VMware VMMouse, HP ILO2 */
        __set_bit(EV_ABS, jd_scratch);
        __set_bit(EV_KEY, jd_scratch);
        __set_bit(EV_SYN, jd_scratch);
        if (bitmap_equal(jd_scratch, dev->evbit, EV_CNT))
                ev_match = true;

        /* HP ILO2, AMI BMC firmware */
        __set_bit(EV_MSC, jd_scratch);
        if (bitmap_equal(jd_scratch, dev->evbit, EV_CNT))
                ev_match = true;

        /* VMware Virtual USB Mouse, QEMU USB Tablet, ATEN BMC firmware */
        __set_bit(EV_REL, jd_scratch);
        if (bitmap_equal(jd_scratch, dev->evbit, EV_CNT))
                ev_match = true;

        if (!ev_match)
                return false;

        bitmap_zero(jd_scratch, ABS_CNT);
        __set_bit(ABS_X, jd_scratch);
        __set_bit(ABS_Y, jd_scratch);
        if (!bitmap_equal(dev->absbit, jd_scratch, ABS_CNT))
                return false;

        bitmap_zero(jd_scratch, KEY_CNT);
        __set_bit(BTN_LEFT, jd_scratch);
        __set_bit(BTN_RIGHT, jd_scratch);
        __set_bit(BTN_MIDDLE, jd_scratch);

        if (!bitmap_equal(dev->keybit, jd_scratch, KEY_CNT))
                return false;

        /*
         * Amiga joystick (amijoy) historically uses left/middle/right
         * button events.
         */
        if (dev->id.bustype == BUS_AMIGA)
                return false;

        return true;
}

static bool joydev_match(struct input_handler *handler, struct input_dev *dev)
{
        /* Disable blacklisted devices */
        if (joydev_dev_is_blacklisted(dev))
                return false;

        /* Avoid absolute mice */
        if (joydev_dev_is_absolute_mouse(dev))
                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_each_set_bit(i, dev->absbit, ABS_CNT) {
                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;
                        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->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);

        error = cdev_device_add(&joydev->cdev, &joydev->dev);
        if (error)
                goto err_cleanup_joydev;

        return 0;

 err_cleanup_joydev:
        joydev_cleanup(joydev);
        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;

        cdev_device_del(&joydev->cdev, &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_Z) },
        },
        {
                .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);