input.c

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/*
 * The input core
 *
 * 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_BASENAME ": " fmt

#include <linux/init.h>
#include <linux/types.h>
#include <linux/idr.h>
#include <linux/input/mt.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/random.h>
#include <linux/major.h>
#include <linux/proc_fs.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/poll.h>
#include <linux/device.h>
#include <linux/mutex.h>
#include <linux/rcupdate.h>
#include "input-compat.h"

MODULE_AUTHOR("Vojtech Pavlik <[email protected]>");
MODULE_DESCRIPTION("Input core");
MODULE_LICENSE("GPL");

#define INPUT_MAX_CHAR_DEVICES      1024
#define INPUT_FIRST_DYNAMIC_DEV     256
static DEFINE_IDA(input_ida);

static LIST_HEAD(input_dev_list);
static LIST_HEAD(input_handler_list);

/*
 * input_mutex protects access to both input_dev_list and input_handler_list.
 * This also causes input_[un]register_device and input_[un]register_handler
 * be mutually exclusive which simplifies locking in drivers implementing
 * input handlers.
 */
static DEFINE_MUTEX(input_mutex);

static const struct input_value input_value_sync = { EV_SYN, SYN_REPORT, 1 };

static inline int is_event_supported(unsigned int code,
                     unsigned long *bm, unsigned int max)
{
    return code <= max && test_bit(code, bm);
}

static int input_defuzz_abs_event(int value, int old_val, int fuzz)
{
    if (fuzz) {
        if (value > old_val - fuzz / 2 && value < old_val + fuzz / 2)
            return old_val;

        if (value > old_val - fuzz && value < old_val + fuzz)
            return (old_val * 3 + value) / 4;

        if (value > old_val - fuzz * 2 && value < old_val + fuzz * 2)
            return (old_val + value) / 2;
    }

    return value;
}

static void input_start_autorepeat(struct input_dev *dev, int code)
{
    if (test_bit(EV_REP, dev->evbit) &&
        dev->rep[REP_PERIOD] && dev->rep[REP_DELAY] &&
        dev->timer.data) {
        dev->repeat_key = code;
        mod_timer(&dev->timer,
              jiffies + msecs_to_jiffies(dev->rep[REP_DELAY]));
    }
}

static void input_stop_autorepeat(struct input_dev *dev)
{
    del_timer(&dev->timer);
}

/*
 * Pass event first through all filters and then, if event has not been
 * filtered out, through all open handles. This function is called with
 * dev->event_lock held and interrupts disabled.
 */
static unsigned int input_to_handler(struct input_handle *handle,
            struct input_value *vals, unsigned int count)
{
    struct input_handler *handler = handle->handler;
    struct input_value *end = vals;
    struct input_value *v;

    for (v = vals; v != vals + count; v++) {
        if (handler->filter &&
            handler->filter(handle, v->type, v->code, v->value))
            continue;
        if (end != v)
            *end = *v;
        end++;
    }

    count = end - vals;
    if (!count)
        return 0;

    if (handler->events)
        handler->events(handle, vals, count);
    else if (handler->event)
        for (v = vals; v != end; v++)
            handler->event(handle, v->type, v->code, v->value);

    return count;
}

/*
 * Pass values first through all filters and then, if event has not been
 * filtered out, through all open handles. This function is called with
 * dev->event_lock held and interrupts disabled.
 */
static void input_pass_values(struct input_dev *dev,
                  struct input_value *vals, unsigned int count)
{
    struct input_handle *handle;
    struct input_value *v;

    if (!count)
        return;

    rcu_read_lock();

    handle = rcu_dereference(dev->grab);
    if (handle) {
        count = input_to_handler(handle, vals, count);
    } else {
        list_for_each_entry_rcu(handle, &dev->h_list, d_node)
            if (handle->open)
                count = input_to_handler(handle, vals, count);
    }

    rcu_read_unlock();

    add_input_randomness(vals->type, vals->code, vals->value);

    /* trigger auto repeat for key events */
    for (v = vals; v != vals + count; v++) {
        if (v->type == EV_KEY && v->value != 2) {
            if (v->value)
                input_start_autorepeat(dev, v->code);
            else
                input_stop_autorepeat(dev);
        }
    }
}

static void input_pass_event(struct input_dev *dev,
                 unsigned int type, unsigned int code, int value)
{
    struct input_value vals[] = { { type, code, value } };

    input_pass_values(dev, vals, ARRAY_SIZE(vals));
}

/*
 * Generate software autorepeat event. Note that we take
 * dev->event_lock here to avoid racing with input_event
 * which may cause keys get "stuck".
 */
static void input_repeat_key(unsigned long data)
{
    struct input_dev *dev = (void *) data;
    unsigned long flags;

    spin_lock_irqsave(&dev->event_lock, flags);

    if (test_bit(dev->repeat_key, dev->key) &&
        is_event_supported(dev->repeat_key, dev->keybit, KEY_MAX)) {
        struct input_value vals[] =  {
            { EV_KEY, dev->repeat_key, 2 },
            input_value_sync
        };

        input_pass_values(dev, vals, ARRAY_SIZE(vals));

        if (dev->rep[REP_PERIOD])
            mod_timer(&dev->timer, jiffies +
                    msecs_to_jiffies(dev->rep[REP_PERIOD]));
    }

    spin_unlock_irqrestore(&dev->event_lock, flags);
}

#define INPUT_IGNORE_EVENT  0
#define INPUT_PASS_TO_HANDLERS  1
#define INPUT_PASS_TO_DEVICE    2
#define INPUT_SLOT      4
#define INPUT_FLUSH     8
#define INPUT_PASS_TO_ALL   (INPUT_PASS_TO_HANDLERS | INPUT_PASS_TO_DEVICE)

static int input_handle_abs_event(struct input_dev *dev,
                  unsigned int code, int *pval)
{
    struct input_mt *mt = dev->mt;
    bool is_mt_event;
    int *pold;

    if (code == ABS_MT_SLOT) {
        /*
         * "Stage" the event; we'll flush it later, when we
         * get actual touch data.
         */
        if (mt && *pval >= 0 && *pval < mt->num_slots)
            mt->slot = *pval;

        return INPUT_IGNORE_EVENT;
    }

    is_mt_event = input_is_mt_value(code);

    if (!is_mt_event) {
        pold = &dev->absinfo[code].value;
    } else if (mt) {
        pold = &mt->slots[mt->slot].abs[code - ABS_MT_FIRST];
    } else {
        /*
         * Bypass filtering for multi-touch events when
         * not employing slots.
         */
        pold = NULL;
    }

    if (pold) {
        *pval = input_defuzz_abs_event(*pval, *pold,
                        dev->absinfo[code].fuzz);
        if (*pold == *pval)
            return INPUT_IGNORE_EVENT;

        *pold = *pval;
    }

    /* Flush pending "slot" event */
    if (is_mt_event && mt && mt->slot != input_abs_get_val(dev, ABS_MT_SLOT)) {
        input_abs_set_val(dev, ABS_MT_SLOT, mt->slot);
        return INPUT_PASS_TO_HANDLERS | INPUT_SLOT;
    }

    return INPUT_PASS_TO_HANDLERS;
}

static int input_get_disposition(struct input_dev *dev,
              unsigned int type, unsigned int code, int value)
{
    int disposition = INPUT_IGNORE_EVENT;

    switch (type) {

    case EV_SYN:
        switch (code) {
        case SYN_CONFIG:
            disposition = INPUT_PASS_TO_ALL;
            break;

        case SYN_REPORT:
            disposition = INPUT_PASS_TO_HANDLERS | INPUT_FLUSH;
            break;
        case SYN_MT_REPORT:
            disposition = INPUT_PASS_TO_HANDLERS;
            break;
        }
        break;

    case EV_KEY:
        if (is_event_supported(code, dev->keybit, KEY_MAX)) {

            /* auto-repeat bypasses state updates */
            if (value == 2) {
                disposition = INPUT_PASS_TO_HANDLERS;
                break;
            }

            if (!!test_bit(code, dev->key) != !!value) {

                __change_bit(code, dev->key);
                disposition = INPUT_PASS_TO_HANDLERS;
            }
        }
        break;

    case EV_SW:
        if (is_event_supported(code, dev->swbit, SW_MAX) &&
            !!test_bit(code, dev->sw) != !!value) {

            __change_bit(code, dev->sw);
            disposition = INPUT_PASS_TO_HANDLERS;
        }
        break;

    case EV_ABS:
        if (is_event_supported(code, dev->absbit, ABS_MAX))
            disposition = input_handle_abs_event(dev, code, &value);

        break;

    case EV_REL:
        if (is_event_supported(code, dev->relbit, REL_MAX) && value)
            disposition = INPUT_PASS_TO_HANDLERS;

        break;

    case EV_MSC:
        if (is_event_supported(code, dev->mscbit, MSC_MAX))
            disposition = INPUT_PASS_TO_ALL;

        break;

    case EV_LED:
        if (is_event_supported(code, dev->ledbit, LED_MAX) &&
            !!test_bit(code, dev->led) != !!value) {

            __change_bit(code, dev->led);
            disposition = INPUT_PASS_TO_ALL;
        }
        break;

    case EV_SND:
        if (is_event_supported(code, dev->sndbit, SND_MAX)) {

            if (!!test_bit(code, dev->snd) != !!value)
                __change_bit(code, dev->snd);
            disposition = INPUT_PASS_TO_ALL;
        }
        break;

    case EV_REP:
        if (code <= REP_MAX && value >= 0 && dev->rep[code] != value) {
            dev->rep[code] = value;
            disposition = INPUT_PASS_TO_ALL;
        }
        break;

    case EV_FF:
        if (value >= 0)
            disposition = INPUT_PASS_TO_ALL;
        break;

    case EV_PWR:
        disposition = INPUT_PASS_TO_ALL;
        break;
    }

    return disposition;
}

static void input_handle_event(struct input_dev *dev,
                   unsigned int type, unsigned int code, int value)
{
    int disposition;

    disposition = input_get_disposition(dev, type, code, value);

    if ((disposition & INPUT_PASS_TO_DEVICE) && dev->event)
        dev->event(dev, type, code, value);

    if (!dev->vals)
        return;

    if (disposition & INPUT_PASS_TO_HANDLERS) {
        struct input_value *v;

        if (disposition & INPUT_SLOT) {
            v = &dev->vals[dev->num_vals++];
            v->type = EV_ABS;
            v->code = ABS_MT_SLOT;
            v->value = dev->mt->slot;
        }

        v = &dev->vals[dev->num_vals++];
        v->type = type;
        v->code = code;
        v->value = value;
    }

    if (disposition & INPUT_FLUSH) {
        if (dev->num_vals >= 2)
            input_pass_values(dev, dev->vals, dev->num_vals);
        dev->num_vals = 0;
    } else if (dev->num_vals >= dev->max_vals - 2) {
        dev->vals[dev->num_vals++] = input_value_sync;
        input_pass_values(dev, dev->vals, dev->num_vals);
        dev->num_vals = 0;
    }

}

void input_event(struct input_dev *dev,
         unsigned int type, unsigned int code, int value)
{
    unsigned long flags;

    if (is_event_supported(type, dev->evbit, EV_MAX)) {

        spin_lock_irqsave(&dev->event_lock, flags);
        input_handle_event(dev, type, code, value);
        spin_unlock_irqrestore(&dev->event_lock, flags);
    }
}
EXPORT_SYMBOL(input_event);

void input_inject_event(struct input_handle *handle,
            unsigned int type, unsigned int code, int value)
{
    struct input_dev *dev = handle->dev;
    struct input_handle *grab;
    unsigned long flags;

    if (is_event_supported(type, dev->evbit, EV_MAX)) {
        spin_lock_irqsave(&dev->event_lock, flags);

        rcu_read_lock();
        grab = rcu_dereference(dev->grab);
        if (!grab || grab == handle)
            input_handle_event(dev, type, code, value);
        rcu_read_unlock();

        spin_unlock_irqrestore(&dev->event_lock, flags);
    }
}
EXPORT_SYMBOL(input_inject_event);

void input_alloc_absinfo(struct input_dev *dev)
{
    if (!dev->absinfo)
        dev->absinfo = kcalloc(ABS_CNT, sizeof(struct input_absinfo),
                    GFP_KERNEL);

    WARN(!dev->absinfo, "%s(): kcalloc() failed?\n", __func__);
}
EXPORT_SYMBOL(input_alloc_absinfo);

void input_set_abs_params(struct input_dev *dev, unsigned int axis,
              int min, int max, int fuzz, int flat)
{
    struct input_absinfo *absinfo;

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

    absinfo = &dev->absinfo[axis];
    absinfo->minimum = min;
    absinfo->maximum = max;
    absinfo->fuzz = fuzz;
    absinfo->flat = flat;

    dev->absbit[BIT_WORD(axis)] |= BIT_MASK(axis);
}
EXPORT_SYMBOL(input_set_abs_params);


int input_grab_device(struct input_handle *handle)
{
    struct input_dev *dev = handle->dev;
    int retval;

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

    if (dev->grab) {
        retval = -EBUSY;
        goto out;
    }

    rcu_assign_pointer(dev->grab, handle);

 out:
    mutex_unlock(&dev->mutex);
    return retval;
}
EXPORT_SYMBOL(input_grab_device);

static void __input_release_device(struct input_handle *handle)
{
    struct input_dev *dev = handle->dev;

    if (dev->grab == handle) {
        rcu_assign_pointer(dev->grab, NULL);
        /* Make sure input_pass_event() notices that grab is gone */
        synchronize_rcu();

        list_for_each_entry(handle, &dev->h_list, d_node)
            if (handle->open && handle->handler->start)
                handle->handler->start(handle);
    }
}

void input_release_device(struct input_handle *handle)
{
    struct input_dev *dev = handle->dev;

    mutex_lock(&dev->mutex);
    __input_release_device(handle);
    mutex_unlock(&dev->mutex);
}
EXPORT_SYMBOL(input_release_device);

int input_open_device(struct input_handle *handle)
{
    struct input_dev *dev = handle->dev;
    int retval;

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

    if (dev->going_away) {
        retval = -ENODEV;
        goto out;
    }

    handle->open++;

    if (!dev->users++ && dev->open)
        retval = dev->open(dev);

    if (retval) {
        dev->users--;
        if (!--handle->open) {
            /*
             * Make sure we are not delivering any more events
             * through this handle
             */
            synchronize_rcu();
        }
    }

 out:
    mutex_unlock(&dev->mutex);
    return retval;
}
EXPORT_SYMBOL(input_open_device);

int input_flush_device(struct input_handle *handle, struct file *file)
{
    struct input_dev *dev = handle->dev;
    int retval;

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

    if (dev->flush)
        retval = dev->flush(dev, file);

    mutex_unlock(&dev->mutex);
    return retval;
}
EXPORT_SYMBOL(input_flush_device);

void input_close_device(struct input_handle *handle)
{
    struct input_dev *dev = handle->dev;

    mutex_lock(&dev->mutex);

    __input_release_device(handle);

    if (!--dev->users && dev->close)
        dev->close(dev);

    if (!--handle->open) {
        /*
         * synchronize_rcu() makes sure that input_pass_event()
         * completed and that no more input events are delivered
         * through this handle
         */
        synchronize_rcu();
    }

    mutex_unlock(&dev->mutex);
}
EXPORT_SYMBOL(input_close_device);

/*
 * Simulate keyup events for all keys that are marked as pressed.
 * The function must be called with dev->event_lock held.
 */
static void input_dev_release_keys(struct input_dev *dev)
{
    int code;

    if (is_event_supported(EV_KEY, dev->evbit, EV_MAX)) {
        for (code = 0; code <= KEY_MAX; code++) {
            if (is_event_supported(code, dev->keybit, KEY_MAX) &&
                __test_and_clear_bit(code, dev->key)) {
                input_pass_event(dev, EV_KEY, code, 0);
            }
        }
        input_pass_event(dev, EV_SYN, SYN_REPORT, 1);
    }
}

/*
 * Prepare device for unregistering
 */
static void input_disconnect_device(struct input_dev *dev)
{
    struct input_handle *handle;

    /*
     * Mark device as going away. Note that we take dev->mutex here
     * not to protect access to dev->going_away but rather to ensure
     * that there are no threads in the middle of input_open_device()
     */
    mutex_lock(&dev->mutex);
    dev->going_away = true;
    mutex_unlock(&dev->mutex);

    spin_lock_irq(&dev->event_lock);

    /*
     * Simulate keyup events for all pressed keys so that handlers
     * are not left with "stuck" keys. The driver may continue
     * generate events even after we done here but they will not
     * reach any handlers.
     */
    input_dev_release_keys(dev);

    list_for_each_entry(handle, &dev->h_list, d_node)
        handle->open = 0;

    spin_unlock_irq(&dev->event_lock);
}

int input_scancode_to_scalar(const struct input_keymap_entry *ke,
                 unsigned int *scancode)
{
    switch (ke->len) {
    case 1:
        *scancode = *((u8 *)ke->scancode);
        break;

    case 2:
        *scancode = *((u16 *)ke->scancode);
        break;

    case 4:
        *scancode = *((u32 *)ke->scancode);
        break;

    default:
        return -EINVAL;
    }

    return 0;
}
EXPORT_SYMBOL(input_scancode_to_scalar);

/*
 * Those routines handle the default case where no [gs]etkeycode() is
 * defined. In this case, an array indexed by the scancode is used.
 */

static unsigned int input_fetch_keycode(struct input_dev *dev,
                    unsigned int index)
{
    switch (dev->keycodesize) {
    case 1:
        return ((u8 *)dev->keycode)[index];

    case 2:
        return ((u16 *)dev->keycode)[index];

    default:
        return ((u32 *)dev->keycode)[index];
    }
}

static int input_default_getkeycode(struct input_dev *dev,
                    struct input_keymap_entry *ke)
{
    unsigned int index;
    int error;

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

    if (ke->flags & INPUT_KEYMAP_BY_INDEX)
        index = ke->index;
    else {
        error = input_scancode_to_scalar(ke, &index);
        if (error)
            return error;
    }

    if (index >= dev->keycodemax)
        return -EINVAL;

    ke->keycode = input_fetch_keycode(dev, index);
    ke->index = index;
    ke->len = sizeof(index);
    memcpy(ke->scancode, &index, sizeof(index));

    return 0;
}

static int input_default_setkeycode(struct input_dev *dev,
                    const struct input_keymap_entry *ke,
                    unsigned int *old_keycode)
{
    unsigned int index;
    int error;
    int i;

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

    if (ke->flags & INPUT_KEYMAP_BY_INDEX) {
        index = ke->index;
    } else {
        error = input_scancode_to_scalar(ke, &index);
        if (error)
            return error;
    }

    if (index >= dev->keycodemax)
        return -EINVAL;

    if (dev->keycodesize < sizeof(ke->keycode) &&
            (ke->keycode >> (dev->keycodesize * 8)))
        return -EINVAL;

    switch (dev->keycodesize) {
        case 1: {
            u8 *k = (u8 *)dev->keycode;
            *old_keycode = k[index];
            k[index] = ke->keycode;
            break;
        }
        case 2: {
            u16 *k = (u16 *)dev->keycode;
            *old_keycode = k[index];
            k[index] = ke->keycode;
            break;
        }
        default: {
            u32 *k = (u32 *)dev->keycode;
            *old_keycode = k[index];
            k[index] = ke->keycode;
            break;
        }
    }

    __clear_bit(*old_keycode, dev->keybit);
    __set_bit(ke->keycode, dev->keybit);

    for (i = 0; i < dev->keycodemax; i++) {
        if (input_fetch_keycode(dev, i) == *old_keycode) {
            __set_bit(*old_keycode, dev->keybit);
            break; /* Setting the bit twice is useless, so break */
        }
    }

    return 0;
}

int input_get_keycode(struct input_dev *dev, struct input_keymap_entry *ke)
{
    unsigned long flags;
    int retval;

    spin_lock_irqsave(&dev->event_lock, flags);
    retval = dev->getkeycode(dev, ke);
    spin_unlock_irqrestore(&dev->event_lock, flags);

    return retval;
}
EXPORT_SYMBOL(input_get_keycode);

int input_set_keycode(struct input_dev *dev,
              const struct input_keymap_entry *ke)
{
    unsigned long flags;
    unsigned int old_keycode;
    int retval;

    if (ke->keycode > KEY_MAX)
        return -EINVAL;

    spin_lock_irqsave(&dev->event_lock, flags);

    retval = dev->setkeycode(dev, ke, &old_keycode);
    if (retval)
        goto out;

    /* Make sure KEY_RESERVED did not get enabled. */
    __clear_bit(KEY_RESERVED, dev->keybit);

    /*
     * Simulate keyup event if keycode is not present
     * in the keymap anymore
     */
    if (test_bit(EV_KEY, dev->evbit) &&
        !is_event_supported(old_keycode, dev->keybit, KEY_MAX) &&
        __test_and_clear_bit(old_keycode, dev->key)) {
        struct input_value vals[] =  {
            { EV_KEY, old_keycode, 0 },
            input_value_sync
        };

        input_pass_values(dev, vals, ARRAY_SIZE(vals));
    }

 out:
    spin_unlock_irqrestore(&dev->event_lock, flags);

    return retval;
}
EXPORT_SYMBOL(input_set_keycode);

static const struct input_device_id *input_match_device(struct input_handler *handler,
                            struct input_dev *dev)
{
    const struct input_device_id *id;

    for (id = handler->id_table; id->flags || id->driver_info; id++) {

        if (id->flags & INPUT_DEVICE_ID_MATCH_BUS)
            if (id->bustype != dev->id.bustype)
                continue;

        if (id->flags & INPUT_DEVICE_ID_MATCH_VENDOR)
            if (id->vendor != dev->id.vendor)
                continue;

        if (id->flags & INPUT_DEVICE_ID_MATCH_PRODUCT)
            if (id->product != dev->id.product)
                continue;

        if (id->flags & INPUT_DEVICE_ID_MATCH_VERSION)
            if (id->version != dev->id.version)
                continue;

        if (!bitmap_subset(id->evbit, dev->evbit, EV_MAX))
            continue;

        if (!bitmap_subset(id->keybit, dev->keybit, KEY_MAX))
            continue;

        if (!bitmap_subset(id->relbit, dev->relbit, REL_MAX))
            continue;

        if (!bitmap_subset(id->absbit, dev->absbit, ABS_MAX))
            continue;

        if (!bitmap_subset(id->mscbit, dev->mscbit, MSC_MAX))
            continue;

        if (!bitmap_subset(id->ledbit, dev->ledbit, LED_MAX))
            continue;

        if (!bitmap_subset(id->sndbit, dev->sndbit, SND_MAX))
            continue;

        if (!bitmap_subset(id->ffbit, dev->ffbit, FF_MAX))
            continue;

        if (!bitmap_subset(id->swbit, dev->swbit, SW_MAX))
            continue;

        if (!handler->match || handler->match(handler, dev))
            return id;
    }

    return NULL;
}

static int input_attach_handler(struct input_dev *dev, struct input_handler *handler)
{
    const struct input_device_id *id;
    int error;

    id = input_match_device(handler, dev);
    if (!id)
        return -ENODEV;

    error = handler->connect(handler, dev, id);
    if (error && error != -ENODEV)
        pr_err("failed to attach handler %s to device %s, error: %d\n",
               handler->name, kobject_name(&dev->dev.kobj), error);

    return error;
}

#ifdef CONFIG_COMPAT

static int input_bits_to_string(char *buf, int buf_size,
                unsigned long bits, bool skip_empty)
{
    int len = 0;

    if (INPUT_COMPAT_TEST) {
        u32 dword = bits >> 32;
        if (dword || !skip_empty)
            len += snprintf(buf, buf_size, "%x ", dword);

        dword = bits & 0xffffffffUL;
        if (dword || !skip_empty || len)
            len += snprintf(buf + len, max(buf_size - len, 0),
                    "%x", dword);
    } else {
        if (bits || !skip_empty)
            len += snprintf(buf, buf_size, "%lx", bits);
    }

    return len;
}

#else /* !CONFIG_COMPAT */

static int input_bits_to_string(char *buf, int buf_size,
                unsigned long bits, bool skip_empty)
{
    return bits || !skip_empty ?
        snprintf(buf, buf_size, "%lx", bits) : 0;
}

#endif

#ifdef CONFIG_PROC_FS

static struct proc_dir_entry *proc_bus_input_dir;
static DECLARE_WAIT_QUEUE_HEAD(input_devices_poll_wait);
static int input_devices_state;

static inline void input_wakeup_procfs_readers(void)
{
    input_devices_state++;
    wake_up(&input_devices_poll_wait);
}

static unsigned int input_proc_devices_poll(struct file *file, poll_table *wait)
{
    poll_wait(file, &input_devices_poll_wait, wait);
    if (file->f_version != input_devices_state) {
        file->f_version = input_devices_state;
        return POLLIN | POLLRDNORM;
    }

    return 0;
}

union input_seq_state {
    struct {
        unsigned short pos;
        bool mutex_acquired;
    };
    void *p;
};

static void *input_devices_seq_start(struct seq_file *seq, loff_t *pos)
{
    union input_seq_state *state = (union input_seq_state *)&seq->private;
    int error;

    /* We need to fit into seq->private pointer */
    BUILD_BUG_ON(sizeof(union input_seq_state) != sizeof(seq->private));

    error = mutex_lock_interruptible(&input_mutex);
    if (error) {
        state->mutex_acquired = false;
        return ERR_PTR(error);
    }

    state->mutex_acquired = true;

    return seq_list_start(&input_dev_list, *pos);
}

static void *input_devices_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
    return seq_list_next(v, &input_dev_list, pos);
}

static void input_seq_stop(struct seq_file *seq, void *v)
{
    union input_seq_state *state = (union input_seq_state *)&seq->private;

    if (state->mutex_acquired)
        mutex_unlock(&input_mutex);
}

static void input_seq_print_bitmap(struct seq_file *seq, const char *name,
                   unsigned long *bitmap, int max)
{
    int i;
    bool skip_empty = true;
    char buf[18];

    seq_printf(seq, "B: %s=", name);

    for (i = BITS_TO_LONGS(max) - 1; i >= 0; i--) {
        if (input_bits_to_string(buf, sizeof(buf),
                     bitmap[i], skip_empty)) {
            skip_empty = false;
            seq_printf(seq, "%s%s", buf, i > 0 ? " " : "");
        }
    }

    /*
     * If no output was produced print a single 0.
     */
    if (skip_empty)
        seq_puts(seq, "0");

    seq_putc(seq, '\n');
}

static int input_devices_seq_show(struct seq_file *seq, void *v)
{
    struct input_dev *dev = container_of(v, struct input_dev, node);
    const char *path = kobject_get_path(&dev->dev.kobj, GFP_KERNEL);
    struct input_handle *handle;

    seq_printf(seq, "I: Bus=%04x Vendor=%04x Product=%04x Version=%04x\n",
           dev->id.bustype, dev->id.vendor, dev->id.product, dev->id.version);

    seq_printf(seq, "N: Name=\"%s\"\n", dev->name ? dev->name : "");
    seq_printf(seq, "P: Phys=%s\n", dev->phys ? dev->phys : "");
    seq_printf(seq, "S: Sysfs=%s\n", path ? path : "");
    seq_printf(seq, "U: Uniq=%s\n", dev->uniq ? dev->uniq : "");
    seq_printf(seq, "H: Handlers=");

    list_for_each_entry(handle, &dev->h_list, d_node)
        seq_printf(seq, "%s ", handle->name);
    seq_putc(seq, '\n');

    input_seq_print_bitmap(seq, "PROP", dev->propbit, INPUT_PROP_MAX);

    input_seq_print_bitmap(seq, "EV", dev->evbit, EV_MAX);
    if (test_bit(EV_KEY, dev->evbit))
        input_seq_print_bitmap(seq, "KEY", dev->keybit, KEY_MAX);
    if (test_bit(EV_REL, dev->evbit))
        input_seq_print_bitmap(seq, "REL", dev->relbit, REL_MAX);
    if (test_bit(EV_ABS, dev->evbit))
        input_seq_print_bitmap(seq, "ABS", dev->absbit, ABS_MAX);
    if (test_bit(EV_MSC, dev->evbit))
        input_seq_print_bitmap(seq, "MSC", dev->mscbit, MSC_MAX);
    if (test_bit(EV_LED, dev->evbit))
        input_seq_print_bitmap(seq, "LED", dev->ledbit, LED_MAX);
    if (test_bit(EV_SND, dev->evbit))
        input_seq_print_bitmap(seq, "SND", dev->sndbit, SND_MAX);
    if (test_bit(EV_FF, dev->evbit))
        input_seq_print_bitmap(seq, "FF", dev->ffbit, FF_MAX);
    if (test_bit(EV_SW, dev->evbit))
        input_seq_print_bitmap(seq, "SW", dev->swbit, SW_MAX);

    seq_putc(seq, '\n');

    kfree(path);
    return 0;
}

static const struct seq_operations input_devices_seq_ops = {
    .start  = input_devices_seq_start,
    .next   = input_devices_seq_next,
    .stop   = input_seq_stop,
    .show   = input_devices_seq_show,
};

static int input_proc_devices_open(struct inode *inode, struct file *file)
{
    return seq_open(file, &input_devices_seq_ops);
}

static const struct file_operations input_devices_fileops = {
    .owner      = THIS_MODULE,
    .open       = input_proc_devices_open,
    .poll       = input_proc_devices_poll,
    .read       = seq_read,
    .llseek     = seq_lseek,
    .release    = seq_release,
};

static void *input_handlers_seq_start(struct seq_file *seq, loff_t *pos)
{
    union input_seq_state *state = (union input_seq_state *)&seq->private;
    int error;

    /* We need to fit into seq->private pointer */
    BUILD_BUG_ON(sizeof(union input_seq_state) != sizeof(seq->private));

    error = mutex_lock_interruptible(&input_mutex);
    if (error) {
        state->mutex_acquired = false;
        return ERR_PTR(error);
    }

    state->mutex_acquired = true;
    state->pos = *pos;

    return seq_list_start(&input_handler_list, *pos);
}

static void *input_handlers_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
    union input_seq_state *state = (union input_seq_state *)&seq->private;

    state->pos = *pos + 1;
    return seq_list_next(v, &input_handler_list, pos);
}

static int input_handlers_seq_show(struct seq_file *seq, void *v)
{
    struct input_handler *handler = container_of(v, struct input_handler, node);
    union input_seq_state *state = (union input_seq_state *)&seq->private;

    seq_printf(seq, "N: Number=%u Name=%s", state->pos, handler->name);
    if (handler->filter)
        seq_puts(seq, " (filter)");
    if (handler->legacy_minors)
        seq_printf(seq, " Minor=%d", handler->minor);
    seq_putc(seq, '\n');

    return 0;
}

static const struct seq_operations input_handlers_seq_ops = {
    .start  = input_handlers_seq_start,
    .next   = input_handlers_seq_next,
    .stop   = input_seq_stop,
    .show   = input_handlers_seq_show,
};

static int input_proc_handlers_open(struct inode *inode, struct file *file)
{
    return seq_open(file, &input_handlers_seq_ops);
}

static const struct file_operations input_handlers_fileops = {
    .owner      = THIS_MODULE,
    .open       = input_proc_handlers_open,
    .read       = seq_read,
    .llseek     = seq_lseek,
    .release    = seq_release,
};

static int __init input_proc_init(void)
{
    struct proc_dir_entry *entry;

    proc_bus_input_dir = proc_mkdir("bus/input", NULL);
    if (!proc_bus_input_dir)
        return -ENOMEM;

    entry = proc_create("devices", 0, proc_bus_input_dir,
                &input_devices_fileops);
    if (!entry)
        goto fail1;

    entry = proc_create("handlers", 0, proc_bus_input_dir,
                &input_handlers_fileops);
    if (!entry)
        goto fail2;

    return 0;

 fail2: remove_proc_entry("devices", proc_bus_input_dir);
 fail1: remove_proc_entry("bus/input", NULL);
    return -ENOMEM;
}

static void input_proc_exit(void)
{
    remove_proc_entry("devices", proc_bus_input_dir);
    remove_proc_entry("handlers", proc_bus_input_dir);
    remove_proc_entry("bus/input", NULL);
}

#else /* !CONFIG_PROC_FS */
static inline void input_wakeup_procfs_readers(void) { }
static inline int input_proc_init(void) { return 0; }
static inline void input_proc_exit(void) { }
#endif

#define INPUT_DEV_STRING_ATTR_SHOW(name)                \
static ssize_t input_dev_show_##name(struct device *dev,        \
                     struct device_attribute *attr, \
                     char *buf)             \
{                                   \
    struct input_dev *input_dev = to_input_dev(dev);        \
                                    \
    return scnprintf(buf, PAGE_SIZE, "%s\n",            \
             input_dev->name ? input_dev->name : "");   \
}                                   \
static DEVICE_ATTR(name, S_IRUGO, input_dev_show_##name, NULL)

INPUT_DEV_STRING_ATTR_SHOW(name);
INPUT_DEV_STRING_ATTR_SHOW(phys);
INPUT_DEV_STRING_ATTR_SHOW(uniq);

static int input_print_modalias_bits(char *buf, int size,
                     char name, unsigned long *bm,
                     unsigned int min_bit, unsigned int max_bit)
{
    int len = 0, i;

    len += snprintf(buf, max(size, 0), "%c", name);
    for (i = min_bit; i < max_bit; i++)
        if (bm[BIT_WORD(i)] & BIT_MASK(i))
            len += snprintf(buf + len, max(size - len, 0), "%X,", i);
    return len;
}

static int input_print_modalias(char *buf, int size, struct input_dev *id,
                int add_cr)
{
    int len;

    len = snprintf(buf, max(size, 0),
               "input:b%04Xv%04Xp%04Xe%04X-",
               id->id.bustype, id->id.vendor,
               id->id.product, id->id.version);

    len += input_print_modalias_bits(buf + len, size - len,
                'e', id->evbit, 0, EV_MAX);
    len += input_print_modalias_bits(buf + len, size - len,
                'k', id->keybit, KEY_MIN_INTERESTING, KEY_MAX);
    len += input_print_modalias_bits(buf + len, size - len,
                'r', id->relbit, 0, REL_MAX);
    len += input_print_modalias_bits(buf + len, size - len,
                'a', id->absbit, 0, ABS_MAX);
    len += input_print_modalias_bits(buf + len, size - len,
                'm', id->mscbit, 0, MSC_MAX);
    len += input_print_modalias_bits(buf + len, size - len,
                'l', id->ledbit, 0, LED_MAX);
    len += input_print_modalias_bits(buf + len, size - len,
                's', id->sndbit, 0, SND_MAX);
    len += input_print_modalias_bits(buf + len, size - len,
                'f', id->ffbit, 0, FF_MAX);
    len += input_print_modalias_bits(buf + len, size - len,
                'w', id->swbit, 0, SW_MAX);

    if (add_cr)
        len += snprintf(buf + len, max(size - len, 0), "\n");

    return len;
}

static ssize_t input_dev_show_modalias(struct device *dev,
                       struct device_attribute *attr,
                       char *buf)
{
    struct input_dev *id = to_input_dev(dev);
    ssize_t len;

    len = input_print_modalias(buf, PAGE_SIZE, id, 1);

    return min_t(int, len, PAGE_SIZE);
}
static DEVICE_ATTR(modalias, S_IRUGO, input_dev_show_modalias, NULL);

static int input_print_bitmap(char *buf, int buf_size, unsigned long *bitmap,
                  int max, int add_cr);

static ssize_t input_dev_show_properties(struct device *dev,
                     struct device_attribute *attr,
                     char *buf)
{
    struct input_dev *input_dev = to_input_dev(dev);
    int len = input_print_bitmap(buf, PAGE_SIZE, input_dev->propbit,
                     INPUT_PROP_MAX, true);
    return min_t(int, len, PAGE_SIZE);
}
static DEVICE_ATTR(properties, S_IRUGO, input_dev_show_properties, NULL);

static struct attribute *input_dev_attrs[] = {
    &dev_attr_name.attr,
    &dev_attr_phys.attr,
    &dev_attr_uniq.attr,
    &dev_attr_modalias.attr,
    &dev_attr_properties.attr,
    NULL
};

static struct attribute_group input_dev_attr_group = {
    .attrs  = input_dev_attrs,
};

#define INPUT_DEV_ID_ATTR(name)                     \
static ssize_t input_dev_show_id_##name(struct device *dev,     \
                    struct device_attribute *attr,  \
                    char *buf)          \
{                                   \
    struct input_dev *input_dev = to_input_dev(dev);        \
    return scnprintf(buf, PAGE_SIZE, "%04x\n", input_dev->id.name); \
}                                   \
static DEVICE_ATTR(name, S_IRUGO, input_dev_show_id_##name, NULL)

INPUT_DEV_ID_ATTR(bustype);
INPUT_DEV_ID_ATTR(vendor);
INPUT_DEV_ID_ATTR(product);
INPUT_DEV_ID_ATTR(version);

static struct attribute *input_dev_id_attrs[] = {
    &dev_attr_bustype.attr,
    &dev_attr_vendor.attr,
    &dev_attr_product.attr,
    &dev_attr_version.attr,
    NULL
};

static struct attribute_group input_dev_id_attr_group = {
    .name   = "id",
    .attrs  = input_dev_id_attrs,
};

static int input_print_bitmap(char *buf, int buf_size, unsigned long *bitmap,
                  int max, int add_cr)
{
    int i;
    int len = 0;
    bool skip_empty = true;

    for (i = BITS_TO_LONGS(max) - 1; i >= 0; i--) {
        len += input_bits_to_string(buf + len, max(buf_size - len, 0),
                        bitmap[i], skip_empty);
        if (len) {
            skip_empty = false;
            if (i > 0)
                len += snprintf(buf + len, max(buf_size - len, 0), " ");
        }
    }

    /*
     * If no output was produced print a single 0.
     */
    if (len == 0)
        len = snprintf(buf, buf_size, "%d", 0);

    if (add_cr)
        len += snprintf(buf + len, max(buf_size - len, 0), "\n");

    return len;
}

#define INPUT_DEV_CAP_ATTR(ev, bm)                  \
static ssize_t input_dev_show_cap_##bm(struct device *dev,      \
                       struct device_attribute *attr,   \
                       char *buf)           \
{                                   \
    struct input_dev *input_dev = to_input_dev(dev);        \
    int len = input_print_bitmap(buf, PAGE_SIZE,            \
                     input_dev->bm##bit, ev##_MAX,  \
                     true);             \
    return min_t(int, len, PAGE_SIZE);              \
}                                   \
static DEVICE_ATTR(bm, S_IRUGO, input_dev_show_cap_##bm, NULL)

INPUT_DEV_CAP_ATTR(EV, ev);
INPUT_DEV_CAP_ATTR(KEY, key);
INPUT_DEV_CAP_ATTR(REL, rel);
INPUT_DEV_CAP_ATTR(ABS, abs);
INPUT_DEV_CAP_ATTR(MSC, msc);
INPUT_DEV_CAP_ATTR(LED, led);
INPUT_DEV_CAP_ATTR(SND, snd);
INPUT_DEV_CAP_ATTR(FF, ff);
INPUT_DEV_CAP_ATTR(SW, sw);

static struct attribute *input_dev_caps_attrs[] = {
    &dev_attr_ev.attr,
    &dev_attr_key.attr,
    &dev_attr_rel.attr,
    &dev_attr_abs.attr,
    &dev_attr_msc.attr,
    &dev_attr_led.attr,
    &dev_attr_snd.attr,
    &dev_attr_ff.attr,
    &dev_attr_sw.attr,
    NULL
};

static struct attribute_group input_dev_caps_attr_group = {
    .name   = "capabilities",
    .attrs  = input_dev_caps_attrs,
};

static const struct attribute_group *input_dev_attr_groups[] = {
    &input_dev_attr_group,
    &input_dev_id_attr_group,
    &input_dev_caps_attr_group,
    NULL
};

static void input_dev_release(struct device *device)
{
    struct input_dev *dev = to_input_dev(device);

    input_ff_destroy(dev);
    input_mt_destroy_slots(dev);
    kfree(dev->absinfo);
    kfree(dev->vals);
    kfree(dev);

    module_put(THIS_MODULE);
}

/*
 * Input uevent interface - loading event handlers based on
 * device bitfields.
 */
static int input_add_uevent_bm_var(struct kobj_uevent_env *env,
                   const char *name, unsigned long *bitmap, int max)
{
    int len;

    if (add_uevent_var(env, "%s", name))
        return -ENOMEM;

    len = input_print_bitmap(&env->buf[env->buflen - 1],
                 sizeof(env->buf) - env->buflen,
                 bitmap, max, false);
    if (len >= (sizeof(env->buf) - env->buflen))
        return -ENOMEM;

    env->buflen += len;
    return 0;
}

static int input_add_uevent_modalias_var(struct kobj_uevent_env *env,
                     struct input_dev *dev)
{
    int len;

    if (add_uevent_var(env, "MODALIAS="))
        return -ENOMEM;

    len = input_print_modalias(&env->buf[env->buflen - 1],
                   sizeof(env->buf) - env->buflen,
                   dev, 0);
    if (len >= (sizeof(env->buf) - env->buflen))
        return -ENOMEM;

    env->buflen += len;
    return 0;
}

#define INPUT_ADD_HOTPLUG_VAR(fmt, val...)              \
    do {                                \
        int err = add_uevent_var(env, fmt, val);        \
        if (err)                        \
            return err;                 \
    } while (0)

#define INPUT_ADD_HOTPLUG_BM_VAR(name, bm, max)             \
    do {                                \
        int err = input_add_uevent_bm_var(env, name, bm, max);  \
        if (err)                        \
            return err;                 \
    } while (0)

#define INPUT_ADD_HOTPLUG_MODALIAS_VAR(dev)             \
    do {                                \
        int err = input_add_uevent_modalias_var(env, dev);  \
        if (err)                        \
            return err;                 \
    } while (0)

static int input_dev_uevent(struct device *device, struct kobj_uevent_env *env)
{
    struct input_dev *dev = to_input_dev(device);

    INPUT_ADD_HOTPLUG_VAR("PRODUCT=%x/%x/%x/%x",
                dev->id.bustype, dev->id.vendor,
                dev->id.product, dev->id.version);
    if (dev->name)
        INPUT_ADD_HOTPLUG_VAR("NAME=\"%s\"", dev->name);
    if (dev->phys)
        INPUT_ADD_HOTPLUG_VAR("PHYS=\"%s\"", dev->phys);
    if (dev->uniq)
        INPUT_ADD_HOTPLUG_VAR("UNIQ=\"%s\"", dev->uniq);

    INPUT_ADD_HOTPLUG_BM_VAR("PROP=", dev->propbit, INPUT_PROP_MAX);

    INPUT_ADD_HOTPLUG_BM_VAR("EV=", dev->evbit, EV_MAX);
    if (test_bit(EV_KEY, dev->evbit))
        INPUT_ADD_HOTPLUG_BM_VAR("KEY=", dev->keybit, KEY_MAX);
    if (test_bit(EV_REL, dev->evbit))
        INPUT_ADD_HOTPLUG_BM_VAR("REL=", dev->relbit, REL_MAX);
    if (test_bit(EV_ABS, dev->evbit))
        INPUT_ADD_HOTPLUG_BM_VAR("ABS=", dev->absbit, ABS_MAX);
    if (test_bit(EV_MSC, dev->evbit))
        INPUT_ADD_HOTPLUG_BM_VAR("MSC=", dev->mscbit, MSC_MAX);
    if (test_bit(EV_LED, dev->evbit))
        INPUT_ADD_HOTPLUG_BM_VAR("LED=", dev->ledbit, LED_MAX);
    if (test_bit(EV_SND, dev->evbit))
        INPUT_ADD_HOTPLUG_BM_VAR("SND=", dev->sndbit, SND_MAX);
    if (test_bit(EV_FF, dev->evbit))
        INPUT_ADD_HOTPLUG_BM_VAR("FF=", dev->ffbit, FF_MAX);
    if (test_bit(EV_SW, dev->evbit))
        INPUT_ADD_HOTPLUG_BM_VAR("SW=", dev->swbit, SW_MAX);

    INPUT_ADD_HOTPLUG_MODALIAS_VAR(dev);

    return 0;
}

#define INPUT_DO_TOGGLE(dev, type, bits, on)                \
    do {                                \
        int i;                          \
        bool active;                        \
                                    \
        if (!test_bit(EV_##type, dev->evbit))           \
            break;                      \
                                    \
        for (i = 0; i < type##_MAX; i++) {          \
            if (!test_bit(i, dev->bits##bit))       \
                continue;               \
                                    \
            active = test_bit(i, dev->bits);        \
            if (!active && !on)             \
                continue;               \
                                    \
            dev->event(dev, EV_##type, i, on ? active : 0); \
        }                           \
    } while (0)

static void input_dev_toggle(struct input_dev *dev, bool activate)
{
    if (!dev->event)
        return;

    INPUT_DO_TOGGLE(dev, LED, led, activate);
    INPUT_DO_TOGGLE(dev, SND, snd, activate);

    if (activate && test_bit(EV_REP, dev->evbit)) {
        dev->event(dev, EV_REP, REP_PERIOD, dev->rep[REP_PERIOD]);
        dev->event(dev, EV_REP, REP_DELAY, dev->rep[REP_DELAY]);
    }
}

void input_reset_device(struct input_dev *dev)
{
    mutex_lock(&dev->mutex);

    if (dev->users) {
        input_dev_toggle(dev, true);

        /*
         * Keys that have been pressed at suspend time are unlikely
         * to be still pressed when we resume.
         */
        spin_lock_irq(&dev->event_lock);
        input_dev_release_keys(dev);
        spin_unlock_irq(&dev->event_lock);
    }

    mutex_unlock(&dev->mutex);
}
EXPORT_SYMBOL(input_reset_device);

#ifdef CONFIG_PM
static int input_dev_suspend(struct device *dev)
{
    struct input_dev *input_dev = to_input_dev(dev);

    mutex_lock(&input_dev->mutex);

    if (input_dev->users)
        input_dev_toggle(input_dev, false);

    mutex_unlock(&input_dev->mutex);

    return 0;
}

static int input_dev_resume(struct device *dev)
{
    struct input_dev *input_dev = to_input_dev(dev);

    input_reset_device(input_dev);

    return 0;
}

static const struct dev_pm_ops input_dev_pm_ops = {
    .suspend    = input_dev_suspend,
    .resume     = input_dev_resume,
    .poweroff   = input_dev_suspend,
    .restore    = input_dev_resume,
};
#endif /* CONFIG_PM */

static struct device_type input_dev_type = {
    .groups     = input_dev_attr_groups,
    .release    = input_dev_release,
    .uevent     = input_dev_uevent,
#ifdef CONFIG_PM
    .pm     = &input_dev_pm_ops,
#endif
};

static char *input_devnode(struct device *dev, umode_t *mode)
{
    return kasprintf(GFP_KERNEL, "input/%s", dev_name(dev));
}

struct class input_class = {
    .name       = "input",
    .devnode    = input_devnode,
};
EXPORT_SYMBOL_GPL(input_class);

struct input_dev *input_allocate_device(void)
{
    struct input_dev *dev;

    dev = kzalloc(sizeof(struct input_dev), GFP_KERNEL);
    if (dev) {
        dev->dev.type = &input_dev_type;
        dev->dev.class = &input_class;
        device_initialize(&dev->dev);
        mutex_init(&dev->mutex);
        spin_lock_init(&dev->event_lock);
        INIT_LIST_HEAD(&dev->h_list);
        INIT_LIST_HEAD(&dev->node);

        __module_get(THIS_MODULE);
    }

    return dev;
}
EXPORT_SYMBOL(input_allocate_device);

void input_free_device(struct input_dev *dev)
{
    if (dev)
        input_put_device(dev);
}
EXPORT_SYMBOL(input_free_device);

void input_set_capability(struct input_dev *dev, unsigned int type, unsigned int code)
{
    switch (type) {
    case EV_KEY:
        __set_bit(code, dev->keybit);
        break;

    case EV_REL:
        __set_bit(code, dev->relbit);
        break;

    case EV_ABS:
        __set_bit(code, dev->absbit);
        break;

    case EV_MSC:
        __set_bit(code, dev->mscbit);
        break;

    case EV_SW:
        __set_bit(code, dev->swbit);
        break;

    case EV_LED:
        __set_bit(code, dev->ledbit);
        break;

    case EV_SND:
        __set_bit(code, dev->sndbit);
        break;

    case EV_FF:
        __set_bit(code, dev->ffbit);
        break;

    case EV_PWR:
        /* do nothing */
        break;

    default:
        pr_err("input_set_capability: unknown type %u (code %u)\n",
               type, code);
        dump_stack();
        return;
    }

    __set_bit(type, dev->evbit);
}
EXPORT_SYMBOL(input_set_capability);

static unsigned int input_estimate_events_per_packet(struct input_dev *dev)
{
    int mt_slots;
    int i;
    unsigned int events;

    if (dev->mt) {
        mt_slots = dev->mt->num_slots;
    } else if (test_bit(ABS_MT_TRACKING_ID, dev->absbit)) {
        mt_slots = dev->absinfo[ABS_MT_TRACKING_ID].maximum -
               dev->absinfo[ABS_MT_TRACKING_ID].minimum + 1,
        mt_slots = clamp(mt_slots, 2, 32);
    } else if (test_bit(ABS_MT_POSITION_X, dev->absbit)) {
        mt_slots = 2;
    } else {
        mt_slots = 0;
    }

    events = mt_slots + 1; /* count SYN_MT_REPORT and SYN_REPORT */

    for (i = 0; i < ABS_CNT; i++) {
        if (test_bit(i, dev->absbit)) {
            if (input_is_mt_axis(i))
                events += mt_slots;
            else
                events++;
        }
    }

    for (i = 0; i < REL_CNT; i++)
        if (test_bit(i, dev->relbit))
            events++;

    /* Make room for KEY and MSC events */
    events += 7;

    return events;
}

#define INPUT_CLEANSE_BITMASK(dev, type, bits)              \
    do {                                \
        if (!test_bit(EV_##type, dev->evbit))           \
            memset(dev->bits##bit, 0,           \
                sizeof(dev->bits##bit));        \
    } while (0)

static void input_cleanse_bitmasks(struct input_dev *dev)
{
    INPUT_CLEANSE_BITMASK(dev, KEY, key);
    INPUT_CLEANSE_BITMASK(dev, REL, rel);
    INPUT_CLEANSE_BITMASK(dev, ABS, abs);
    INPUT_CLEANSE_BITMASK(dev, MSC, msc);
    INPUT_CLEANSE_BITMASK(dev, LED, led);
    INPUT_CLEANSE_BITMASK(dev, SND, snd);
    INPUT_CLEANSE_BITMASK(dev, FF, ff);
    INPUT_CLEANSE_BITMASK(dev, SW, sw);
}

int input_register_device(struct input_dev *dev)
{
    static atomic_t input_no = ATOMIC_INIT(0);
    struct input_handler *handler;
    unsigned int packet_size;
    const char *path;
    int error;

    /* Every input device generates EV_SYN/SYN_REPORT events. */
    __set_bit(EV_SYN, dev->evbit);

    /* KEY_RESERVED is not supposed to be transmitted to userspace. */
    __clear_bit(KEY_RESERVED, dev->keybit);

    /* Make sure that bitmasks not mentioned in dev->evbit are clean. */
    input_cleanse_bitmasks(dev);

    packet_size = input_estimate_events_per_packet(dev);
    if (dev->hint_events_per_packet < packet_size)
        dev->hint_events_per_packet = packet_size;

    dev->max_vals = max(dev->hint_events_per_packet, packet_size) + 2;
    dev->vals = kcalloc(dev->max_vals, sizeof(*dev->vals), GFP_KERNEL);
    if (!dev->vals)
        return -ENOMEM;

    /*
     * If delay and period are pre-set by the driver, then autorepeating
     * is handled by the driver itself and we don't do it in input.c.
     */
    init_timer(&dev->timer);
    if (!dev->rep[REP_DELAY] && !dev->rep[REP_PERIOD]) {
        dev->timer.data = (long) dev;
        dev->timer.function = input_repeat_key;
        dev->rep[REP_DELAY] = 250;
        dev->rep[REP_PERIOD] = 33;
    }

    if (!dev->getkeycode)
        dev->getkeycode = input_default_getkeycode;

    if (!dev->setkeycode)
        dev->setkeycode = input_default_setkeycode;

    dev_set_name(&dev->dev, "input%ld",
             (unsigned long) atomic_inc_return(&input_no) - 1);

    error = device_add(&dev->dev);
    if (error)
        return error;

    path = kobject_get_path(&dev->dev.kobj, GFP_KERNEL);
    pr_info("%s as %s\n",
        dev->name ? dev->name : "Unspecified device",
        path ? path : "N/A");
    kfree(path);

    error = mutex_lock_interruptible(&input_mutex);
    if (error) {
        device_del(&dev->dev);
        return error;
    }

    list_add_tail(&dev->node, &input_dev_list);

    list_for_each_entry(handler, &input_handler_list, node)
        input_attach_handler(dev, handler);

    input_wakeup_procfs_readers();

    mutex_unlock(&input_mutex);

    return 0;
}
EXPORT_SYMBOL(input_register_device);

void input_unregister_device(struct input_dev *dev)
{
    struct input_handle *handle, *next;

    input_disconnect_device(dev);

    mutex_lock(&input_mutex);

    list_for_each_entry_safe(handle, next, &dev->h_list, d_node)
        handle->handler->disconnect(handle);
    WARN_ON(!list_empty(&dev->h_list));

    del_timer_sync(&dev->timer);
    list_del_init(&dev->node);

    input_wakeup_procfs_readers();

    mutex_unlock(&input_mutex);

    device_unregister(&dev->dev);
}
EXPORT_SYMBOL(input_unregister_device);

int input_register_handler(struct input_handler *handler)
{
    struct input_dev *dev;
    int error;

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

    INIT_LIST_HEAD(&handler->h_list);

    list_add_tail(&handler->node, &input_handler_list);

    list_for_each_entry(dev, &input_dev_list, node)
        input_attach_handler(dev, handler);

    input_wakeup_procfs_readers();

    mutex_unlock(&input_mutex);
    return 0;
}
EXPORT_SYMBOL(input_register_handler);

void input_unregister_handler(struct input_handler *handler)
{
    struct input_handle *handle, *next;

    mutex_lock(&input_mutex);

    list_for_each_entry_safe(handle, next, &handler->h_list, h_node)
        handler->disconnect(handle);
    WARN_ON(!list_empty(&handler->h_list));

    list_del_init(&handler->node);

    input_wakeup_procfs_readers();

    mutex_unlock(&input_mutex);
}
EXPORT_SYMBOL(input_unregister_handler);

int input_handler_for_each_handle(struct input_handler *handler, void *data,
                  int (*fn)(struct input_handle *, void *))
{
    struct input_handle *handle;
    int retval = 0;

    rcu_read_lock();

    list_for_each_entry_rcu(handle, &handler->h_list, h_node) {
        retval = fn(handle, data);
        if (retval)
            break;
    }

    rcu_read_unlock();

    return retval;
}
EXPORT_SYMBOL(input_handler_for_each_handle);

int input_register_handle(struct input_handle *handle)
{
    struct input_handler *handler = handle->handler;
    struct input_dev *dev = handle->dev;
    int error;

    /*
     * We take dev->mutex here to prevent race with
     * input_release_device().
     */
    error = mutex_lock_interruptible(&dev->mutex);
    if (error)
        return error;

    /*
     * Filters go to the head of the list, normal handlers
     * to the tail.
     */
    if (handler->filter)
        list_add_rcu(&handle->d_node, &dev->h_list);
    else
        list_add_tail_rcu(&handle->d_node, &dev->h_list);

    mutex_unlock(&dev->mutex);

    /*
     * Since we are supposed to be called from ->connect()
     * which is mutually exclusive with ->disconnect()
     * we can't be racing with input_unregister_handle()
     * and so separate lock is not needed here.
     */
    list_add_tail_rcu(&handle->h_node, &handler->h_list);

    if (handler->start)
        handler->start(handle);

    return 0;
}
EXPORT_SYMBOL(input_register_handle);

void input_unregister_handle(struct input_handle *handle)
{
    struct input_dev *dev = handle->dev;

    list_del_rcu(&handle->h_node);

    /*
     * Take dev->mutex to prevent race with input_release_device().
     */
    mutex_lock(&dev->mutex);
    list_del_rcu(&handle->d_node);
    mutex_unlock(&dev->mutex);

    synchronize_rcu();
}
EXPORT_SYMBOL(input_unregister_handle);

int input_get_new_minor(int legacy_base, unsigned int legacy_num,
            bool allow_dynamic)
{
    /*
     * This function should be called from input handler's ->connect()
     * methods, which are serialized with input_mutex, so no additional
     * locking is needed here.
     */
    if (legacy_base >= 0) {
        int minor = ida_simple_get(&input_ida,
                       legacy_base,
                       legacy_base + legacy_num,
                       GFP_KERNEL);
        if (minor >= 0 || !allow_dynamic)
            return minor;
    }

    return ida_simple_get(&input_ida,
                  INPUT_FIRST_DYNAMIC_DEV, INPUT_MAX_CHAR_DEVICES,
                  GFP_KERNEL);
}
EXPORT_SYMBOL(input_get_new_minor);

void input_free_minor(unsigned int minor)
{
    ida_simple_remove(&input_ida, minor);
}
EXPORT_SYMBOL(input_free_minor);

static int __init input_init(void)
{
    int err;

    err = class_register(&input_class);
    if (err) {
        pr_err("unable to register input_dev class\n");
        return err;
    }

    err = input_proc_init();
    if (err)
        goto fail1;

    err = register_chrdev_region(MKDEV(INPUT_MAJOR, 0),
                     INPUT_MAX_CHAR_DEVICES, "input");
    if (err) {
        pr_err("unable to register char major %d", INPUT_MAJOR);
        goto fail2;
    }

    return 0;

 fail2: input_proc_exit();
 fail1: class_unregister(&input_class);
    return err;
}

static void __exit input_exit(void)
{
    input_proc_exit();
    unregister_chrdev_region(MKDEV(INPUT_MAJOR, 0),
                 INPUT_MAX_CHAR_DEVICES);
    class_unregister(&input_class);
}

subsys_initcall(input_init);
module_exit(input_exit);