xref: /linux/drivers/input/input.c (revision 0fc8f6200d2313278fbf4539bbab74677c685531)

// SPDX-License-Identifier: GPL-2.0-only
/*
 * The input core
 *
 * Copyright (c) 1999-2002 Vojtech Pavlik
 */


#define pr_fmt(fmt) KBUILD_BASENAME ": " fmt

#include <linux/export.h>
#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/pm.h>
#include <linux/poll.h>
#include <linux/device.h>
#include <linux/kstrtox.h>
#include <linux/mutex.h>
#include <linux/rcupdate.h>
#include "input-compat.h"
#include "input-core-private.h"
#include "input-poller.h"

MODULE_AUTHOR("Vojtech Pavlik <vojtech@suse.cz>");
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 const unsigned int input_max_code[EV_CNT] = {
	[EV_KEY] = KEY_MAX,
	[EV_REL] = REL_MAX,
	[EV_ABS] = ABS_MAX,
	[EV_MSC] = MSC_MAX,
	[EV_SW] = SW_MAX,
	[EV_LED] = LED_MAX,
	[EV_SND] = SND_MAX,
	[EV_FF] = FF_MAX,
};

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.function) {
		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)
{
	timer_delete(&dev->timer);
}

/*
 * Pass values first through all filters and then, if event has not been
 * filtered out, through all open handles. This order is achieved by placing
 * filters at the head of the list of handles attached to the device, and
 * placing regular handles at the tail of the list.
 *
 * 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;

	lockdep_assert_held(&dev->event_lock);

	scoped_guard(rcu) {
		handle = rcu_dereference(dev->grab);
		if (handle) {
			count = handle->handle_events(handle, vals, count);
			break;
		}

		list_for_each_entry_rcu(handle, &dev->h_list, d_node) {
			if (handle->open) {
				count = handle->handle_events(handle, vals,
							      count);
				if (!count)
					break;
			}
		}
	}

	/* trigger auto repeat for key events */
	if (test_bit(EV_REP, dev->evbit) && test_bit(EV_KEY, dev->evbit)) {
		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);
			}
		}
	}
}

#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_new_slot = false;
	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];
		is_new_slot = mt->slot != dev->absinfo[ABS_MT_SLOT].value;
	} 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_new_slot) {
		dev->absinfo[ABS_MT_SLOT].value = 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 *pval)
{
	int disposition = INPUT_IGNORE_EVENT;
	int value = *pval;

	/* filter-out events from inhibited devices */
	if (dev->inhibited)
		return 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;
	}

	*pval = value;
	return disposition;
}

static void input_event_dispose(struct input_dev *dev, int disposition,
				unsigned int type, unsigned int code, int value)
{
	if ((disposition & INPUT_PASS_TO_DEVICE) && dev->event)
		dev->event(dev, type, code, value);

	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;
		/*
		 * Reset the timestamp on flush so we won't end up
		 * with a stale one. Note we only need to reset the
		 * monolithic one as we use its presence when deciding
		 * whether to generate a synthetic timestamp.
		 */
		dev->timestamp[INPUT_CLK_MONO] = ktime_set(0, 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_handle_event(struct input_dev *dev,
			unsigned int type, unsigned int code, int value)
{
	int disposition;

	lockdep_assert_held(&dev->event_lock);

	disposition = input_get_disposition(dev, type, code, &value);
	if (disposition != INPUT_IGNORE_EVENT) {
		if (type != EV_SYN)
			add_input_randomness(type, code, value);

		input_event_dispose(dev, disposition, type, code, value);
	}
}

/**
 * input_event() - report new input event
 * @dev: device that generated the event
 * @type: type of the event
 * @code: event code
 * @value: value of the event
 *
 * This function should be used by drivers implementing various input
 * devices to report input events. See also input_inject_event().
 *
 * NOTE: input_event() may be safely used right after input device was
 * allocated with input_allocate_device(), even before it is registered
 * with input_register_device(), but the event will not reach any of the
 * input handlers. Such early invocation of input_event() may be used
 * to 'seed' initial state of a switch or initial position of absolute
 * axis, etc.
 */
void input_event(struct input_dev *dev,
		 unsigned int type, unsigned int code, int value)
{
	if (is_event_supported(type, dev->evbit, EV_MAX)) {
		guard(spinlock_irqsave)(&dev->event_lock);
		input_handle_event(dev, type, code, value);
	}
}
EXPORT_SYMBOL(input_event);

/**
 * input_inject_event() - send input event from input handler
 * @handle: input handle to send event through
 * @type: type of the event
 * @code: event code
 * @value: value of the event
 *
 * Similar to input_event() but will ignore event if device is
 * "grabbed" and handle injecting event is not the one that owns
 * the device.
 */
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;

	if (is_event_supported(type, dev->evbit, EV_MAX)) {
		guard(spinlock_irqsave)(&dev->event_lock);
		guard(rcu)();

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

	}
}
EXPORT_SYMBOL(input_inject_event);

/**
 * input_alloc_absinfo - allocates array of input_absinfo structs
 * @dev: the input device emitting absolute events
 *
 * If the absinfo struct the caller asked for is already allocated, this
 * functions will not do anything.
 */
void input_alloc_absinfo(struct input_dev *dev)
{
	if (dev->absinfo)
		return;

	dev->absinfo = kzalloc_objs(*dev->absinfo, ABS_CNT);
	if (!dev->absinfo) {
		dev_err(dev->dev.parent ?: &dev->dev,
			"%s: unable to allocate memory\n", __func__);
		/*
		 * We will handle this allocation failure in
		 * input_register_device() when we refuse to register input
		 * device with ABS bits but without absinfo.
		 */
	}
}
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;

	__set_bit(EV_ABS, dev->evbit);
	__set_bit(axis, dev->absbit);

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

	absinfo = &dev->absinfo[axis];
	absinfo->minimum = min;
	absinfo->maximum = max;
	absinfo->fuzz = fuzz;
	absinfo->flat = flat;
}
EXPORT_SYMBOL(input_set_abs_params);

/**
 * input_copy_abs - Copy absinfo from one input_dev to another
 * @dst: Destination input device to copy the abs settings to
 * @dst_axis: ABS_* value selecting the destination axis
 * @src: Source input device to copy the abs settings from
 * @src_axis: ABS_* value selecting the source axis
 *
 * Set absinfo for the selected destination axis by copying it from
 * the specified source input device's source axis.
 * This is useful to e.g. setup a pen/stylus input-device for combined
 * touchscreen/pen hardware where the pen uses the same coordinates as
 * the touchscreen.
 */
void input_copy_abs(struct input_dev *dst, unsigned int dst_axis,
		    const struct input_dev *src, unsigned int src_axis)
{
	/* src must have EV_ABS and src_axis set */
	if (WARN_ON(!(test_bit(EV_ABS, src->evbit) &&
		      test_bit(src_axis, src->absbit))))
		return;

	/*
	 * input_alloc_absinfo() may have failed for the source. Our caller is
	 * expected to catch this when registering the input devices, which may
	 * happen after the input_copy_abs() call.
	 */
	if (!src->absinfo)
		return;

	input_set_capability(dst, EV_ABS, dst_axis);
	if (!dst->absinfo)
		return;

	dst->absinfo[dst_axis] = src->absinfo[src_axis];
}
EXPORT_SYMBOL(input_copy_abs);

/**
 * input_grab_device - grabs device for exclusive use
 * @handle: input handle that wants to own the device
 *
 * When a device is grabbed by an input handle all events generated by
 * the device are delivered only to this handle. Also events injected
 * by other input handles are ignored while device is grabbed.
 */
int input_grab_device(struct input_handle *handle)
{
	struct input_dev *dev = handle->dev;

	scoped_cond_guard(mutex_intr, return -EINTR, &dev->mutex) {
		if (dev->grab)
			return -EBUSY;

		rcu_assign_pointer(dev->grab, handle);
	}

	return 0;
}
EXPORT_SYMBOL(input_grab_device);

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

	grabber = rcu_dereference_protected(dev->grab,
					    lockdep_is_held(&dev->mutex));
	if (grabber == handle) {
		rcu_assign_pointer(dev->grab, NULL);
		/* Make sure input_pass_values() 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);
	}
}

/**
 * input_release_device - release previously grabbed device
 * @handle: input handle that owns the device
 *
 * Releases previously grabbed device so that other input handles can
 * start receiving input events. Upon release all handlers attached
 * to the device have their start() method called so they have a change
 * to synchronize device state with the rest of the system.
 */
void input_release_device(struct input_handle *handle)
{
	struct input_dev *dev = handle->dev;

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

/**
 * input_open_device - open input device
 * @handle: handle through which device is being accessed
 *
 * This function should be called by input handlers when they
 * want to start receive events from given input device.
 */
int input_open_device(struct input_handle *handle)
{
	struct input_dev *dev = handle->dev;
	int error;

	scoped_cond_guard(mutex_intr, return -EINTR, &dev->mutex) {
		if (dev->going_away)
			return -ENODEV;

		handle->open++;

		if (handle->handler->passive_observer)
			return 0;

		if (dev->users++ || dev->inhibited) {
			/*
			 * Device is already opened and/or inhibited,
			 * so we can exit immediately and report success.
			 */
			return 0;
		}

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

		if (dev->poller)
			input_dev_poller_start(dev->poller);
	}

	return 0;
}
EXPORT_SYMBOL(input_open_device);

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

	scoped_cond_guard(mutex_intr, return -EINTR, &dev->mutex) {
		if (dev->flush)
			return dev->flush(dev, file);
	}

	return 0;
}
EXPORT_SYMBOL(input_flush_device);

/**
 * input_close_device - close input device
 * @handle: handle through which device is being accessed
 *
 * This function should be called by input handlers when they
 * want to stop receive events from given input device.
 */
void input_close_device(struct input_handle *handle)
{
	struct input_dev *dev = handle->dev;

	guard(mutex)(&dev->mutex);

	__input_release_device(handle);

	if (!handle->handler->passive_observer) {
		if (!--dev->users && !dev->inhibited) {
			if (dev->poller)
				input_dev_poller_stop(dev->poller);
			if (dev->close)
				dev->close(dev);
		}
	}

	if (!--handle->open) {
		/*
		 * synchronize_rcu() makes sure that input_pass_values()
		 * completed and that no more input events are delivered
		 * through this handle
		 */
		synchronize_rcu();
	}
}
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 bool input_dev_release_keys(struct input_dev *dev)
{
	bool need_sync = false;
	int code;

	lockdep_assert_held(&dev->event_lock);

	if (is_event_supported(EV_KEY, dev->evbit, EV_MAX)) {
		for_each_set_bit(code, dev->key, KEY_CNT) {
			input_handle_event(dev, EV_KEY, code, 0);
			need_sync = true;
		}
	}

	return need_sync;
}

/*
 * 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()
	 */
	scoped_guard(mutex, &dev->mutex)
		dev->going_away = true;

	guard(spinlock_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.
	 */
	if (input_dev_release_keys(dev))
		input_handle_event(dev, EV_SYN, SYN_REPORT, 1);

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

/**
 * input_scancode_to_scalar() - converts scancode in &struct input_keymap_entry
 * @ke: keymap entry containing scancode to be converted.
 * @scancode: pointer to the location where converted scancode should
 *	be stored.
 *
 * This function is used to convert scancode stored in &struct keymap_entry
 * into scalar form understood by legacy keymap handling methods. These
 * methods expect scancodes to be represented as 'unsigned int'.
 */
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;
}

/**
 * input_default_setkeycode - default setkeycode method
 * @dev: input device which keymap is being updated.
 * @ke: new keymap entry.
 * @old_keycode: pointer to the location where old keycode should be stored.
 *
 * This function is the default implementation of &input_dev.setkeycode()
 * method. It is typically used when a driver does not provide its own
 * implementation, but it is also exported so drivers can extend it.
 *
 * The function must be called with &input_dev.event_lock held.
 *
 * Return: 0 on success, or a negative error code on failure.
 */
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;

	lockdep_assert_held(&dev->event_lock);

	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;
		}
	}

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

	__set_bit(ke->keycode, dev->keybit);
	return 0;
}
EXPORT_SYMBOL(input_default_setkeycode);

/**
 * input_get_keycode - retrieve keycode currently mapped to a given scancode
 * @dev: input device which keymap is being queried
 * @ke: keymap entry
 *
 * This function should be called by anyone interested in retrieving current
 * keymap. Presently evdev handlers use it.
 */
int input_get_keycode(struct input_dev *dev, struct input_keymap_entry *ke)
{
	guard(spinlock_irqsave)(&dev->event_lock);

	return dev->getkeycode(dev, ke);
}
EXPORT_SYMBOL(input_get_keycode);

/**
 * input_set_keycode - attribute a keycode to a given scancode
 * @dev: input device which keymap is being updated
 * @ke: new keymap entry
 *
 * This function should be called by anyone needing to update current
 * keymap. Presently keyboard and evdev handlers use it.
 */
int input_set_keycode(struct input_dev *dev,
		      const struct input_keymap_entry *ke)
{
	unsigned int old_keycode;
	int error;

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

	guard(spinlock_irqsave)(&dev->event_lock);

	error = dev->setkeycode(dev, ke, &old_keycode);
	if (error)
		return error;

	/* 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 (old_keycode > KEY_MAX) {
		dev_warn(dev->dev.parent ?: &dev->dev,
			 "%s: got too big old keycode %#x\n",
			 __func__, old_keycode);
	} else if (test_bit(EV_KEY, dev->evbit) &&
		   !is_event_supported(old_keycode, dev->keybit, KEY_MAX) &&
		   __test_and_clear_bit(old_keycode, dev->key)) {
		/*
		 * We have to use input_event_dispose() here directly instead
		 * of input_handle_event() because the key we want to release
		 * here is considered no longer supported by the device and
		 * input_handle_event() will ignore it.
		 */
		input_event_dispose(dev, INPUT_PASS_TO_HANDLERS,
				    EV_KEY, old_keycode, 0);
		input_event_dispose(dev, INPUT_PASS_TO_HANDLERS | INPUT_FLUSH,
				    EV_SYN, SYN_REPORT, 1);
	}

	return 0;
}
EXPORT_SYMBOL(input_set_keycode);

bool input_match_device_id(const struct input_dev *dev,
			   const struct input_device_id *id)
{
	if (id->flags & INPUT_DEVICE_ID_MATCH_BUS)
		if (id->bustype != dev->id.bustype)
			return false;

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

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

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

	if (!bitmap_subset(id->evbit, dev->evbit, EV_MAX) ||
	    !bitmap_subset(id->keybit, dev->keybit, KEY_MAX) ||
	    !bitmap_subset(id->relbit, dev->relbit, REL_MAX) ||
	    !bitmap_subset(id->absbit, dev->absbit, ABS_MAX) ||
	    !bitmap_subset(id->mscbit, dev->mscbit, MSC_MAX) ||
	    !bitmap_subset(id->ledbit, dev->ledbit, LED_MAX) ||
	    !bitmap_subset(id->sndbit, dev->sndbit, SND_MAX) ||
	    !bitmap_subset(id->ffbit, dev->ffbit, FF_MAX) ||
	    !bitmap_subset(id->swbit, dev->swbit, SW_MAX) ||
	    !bitmap_subset(id->propbit, dev->propbit, INPUT_PROP_MAX)) {
		return false;
	}

	return true;
}
EXPORT_SYMBOL(input_match_device_id);

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++) {
		if (input_match_device_id(dev, id) &&
		    (!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_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);
}

struct input_seq_state {
	unsigned short pos;
	bool mutex_acquired;
	int input_devices_state;
};

static __poll_t input_proc_devices_poll(struct file *file, poll_table *wait)
{
	struct seq_file *seq = file->private_data;
	struct input_seq_state *state = seq->private;

	poll_wait(file, &input_devices_poll_wait, wait);
	if (state->input_devices_state != input_devices_state) {
		state->input_devices_state = input_devices_state;
		return EPOLLIN | EPOLLRDNORM;
	}

	return 0;
}

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

	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)
{
	struct input_seq_state *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_putc(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_puts(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_private(file, &input_devices_seq_ops,
				sizeof(struct input_seq_state));
}

static const struct proc_ops input_devices_proc_ops = {
	.proc_open	= input_proc_devices_open,
	.proc_poll	= input_proc_devices_poll,
	.proc_read	= seq_read,
	.proc_lseek	= seq_lseek,
	.proc_release	= seq_release_private,
};

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

	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)
{
	struct input_seq_state *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);
	struct input_seq_state *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_private(file, &input_handlers_seq_ops,
				sizeof(struct input_seq_state));
}

static const struct proc_ops input_handlers_proc_ops = {
	.proc_open	= input_proc_handlers_open,
	.proc_read	= seq_read,
	.proc_lseek	= seq_lseek,
	.proc_release	= seq_release_private,
};

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_proc_ops);
	if (!entry)
		goto fail1;

	entry = proc_create("handlers", 0, proc_bus_input_dir,
			    &input_handlers_proc_ops);
	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 sysfs_emit(buf, "%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, const unsigned long *bm,
				     unsigned int min_bit, unsigned int max_bit)
{
	int bit = min_bit;
	int len = 0;

	len += snprintf(buf, max(size, 0), "%c", name);
	for_each_set_bit_from(bit, bm, max_bit)
		len += snprintf(buf + len, max(size - len, 0), "%X,", bit);
	return len;
}

static int input_print_modalias_parts(char *buf, int size, int full_len,
				      const struct input_dev *id)
{
	int len, klen, remainder, space;

	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);

	/*
	 * Calculate the remaining space in the buffer making sure we
	 * have place for the terminating 0.
	 */
	space = max(size - (len + 1), 0);

	klen = input_print_modalias_bits(buf + len, size - len,
				'k', id->keybit, KEY_MIN_INTERESTING, KEY_MAX);
	len += klen;

	/*
	 * If we have more data than we can fit in the buffer, check
	 * if we can trim key data to fit in the rest. We will indicate
	 * that key data is incomplete by adding "+" sign at the end, like
	 * this: * "k1,2,3,45,+,".
	 *
	 * Note that we shortest key info (if present) is "k+," so we
	 * can only try to trim if key data is longer than that.
	 */
	if (full_len && size < full_len + 1 && klen > 3) {
		remainder = full_len - len;
		/*
		 * We can only trim if we have space for the remainder
		 * and also for at least "k+," which is 3 more characters.
		 */
		if (remainder <= space - 3) {
			/*
			 * We are guaranteed to have 'k' in the buffer, so
			 * we need at least 3 additional bytes for storing
			 * "+," in addition to the remainder.
			 */
			for (int i = size - 1 - remainder - 3; i >= 0; i--) {
				if (buf[i] == 'k' || buf[i] == ',') {
					strcpy(buf + i + 1, "+,");
					len = i + 3; /* Not counting '\0' */
					break;
				}
			}
		}
	}

	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);

	return len;
}

static int input_print_modalias(char *buf, int size, const struct input_dev *id)
{
	int full_len;

	/*
	 * Printing is done in 2 passes: first one figures out total length
	 * needed for the modalias string, second one will try to trim key
	 * data in case when buffer is too small for the entire modalias.
	 * If the buffer is too small regardless, it will fill as much as it
	 * can (without trimming key data) into the buffer and leave it to
	 * the caller to figure out what to do with the result.
	 */
	full_len = input_print_modalias_parts(NULL, 0, 0, id);
	return input_print_modalias_parts(buf, size, full_len, id);
}

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);
	if (len < PAGE_SIZE - 2)
		len += snprintf(buf + len, PAGE_SIZE - len, "\n");

	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, const 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 int input_inhibit_device(struct input_dev *dev);
static int input_uninhibit_device(struct input_dev *dev);

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

	return sysfs_emit(buf, "%d\n", input_dev->inhibited);
}

static ssize_t inhibited_store(struct device *dev,
			       struct device_attribute *attr, const char *buf,
			       size_t len)
{
	struct input_dev *input_dev = to_input_dev(dev);
	ssize_t rv;
	bool inhibited;

	if (kstrtobool(buf, &inhibited))
		return -EINVAL;

	if (inhibited)
		rv = input_inhibit_device(input_dev);
	else
		rv = input_uninhibit_device(input_dev);

	if (rv != 0)
		return rv;

	return len;
}

static DEVICE_ATTR_RW(inhibited);

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,
	&dev_attr_inhibited.attr,
	NULL
};

static const 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 sysfs_emit(buf, "%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 const 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, const 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 const 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,
	&input_poller_attribute_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->poller);
	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, const 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;
}

/*
 * This is a pretty gross hack. When building uevent data the driver core
 * may try adding more environment variables to kobj_uevent_env without
 * telling us, so we have no idea how much of the buffer we can use to
 * avoid overflows/-ENOMEM elsewhere. To work around this let's artificially
 * reduce amount of memory we will use for the modalias environment variable.
 *
 * The potential additions are:
 *
 * SEQNUM=18446744073709551615 - (%llu - 28 bytes)
 * HOME=/ (6 bytes)
 * PATH=/sbin:/bin:/usr/sbin:/usr/bin (34 bytes)
 *
 * 68 bytes total. Allow extra buffer - 96 bytes
 */
#define UEVENT_ENV_EXTRA_LEN	96

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

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

	len = input_print_modalias(&env->buf[env->buflen - 1],
				   (int)sizeof(env->buf) - env->buflen -
					UEVENT_ENV_EXTRA_LEN,
				   dev);
	if (len >= ((int)sizeof(env->buf) - env->buflen -
					UEVENT_ENV_EXTRA_LEN))
		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(const struct device *device, struct kobj_uevent_env *env)
{
	const 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_each_set_bit(i, dev->bits##bit, type##_CNT) {	\
			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]);
	}
}

/**
 * input_reset_device() - reset/restore the state of input device
 * @dev: input device whose state needs to be reset
 *
 * This function tries to reset the state of an opened input device and
 * bring internal state and state if the hardware in sync with each other.
 * We mark all keys as released, restore LED state, repeat rate, etc.
 */
void input_reset_device(struct input_dev *dev)
{
	guard(mutex)(&dev->mutex);
	guard(spinlock_irqsave)(&dev->event_lock);

	input_dev_toggle(dev, true);
	if (input_dev_release_keys(dev))
		input_handle_event(dev, EV_SYN, SYN_REPORT, 1);
}
EXPORT_SYMBOL(input_reset_device);

static int input_inhibit_device(struct input_dev *dev)
{
	guard(mutex)(&dev->mutex);

	if (dev->inhibited)
		return 0;

	if (dev->users) {
		if (dev->close)
			dev->close(dev);
		if (dev->poller)
			input_dev_poller_stop(dev->poller);
	}

	scoped_guard(spinlock_irq, &dev->event_lock) {
		input_mt_release_slots(dev);
		input_dev_release_keys(dev);
		input_handle_event(dev, EV_SYN, SYN_REPORT, 1);
		input_dev_toggle(dev, false);
	}

	dev->inhibited = true;

	return 0;
}

static int input_uninhibit_device(struct input_dev *dev)
{
	int error;

	guard(mutex)(&dev->mutex);

	if (!dev->inhibited)
		return 0;

	if (dev->users) {
		if (dev->open) {
			error = dev->open(dev);
			if (error)
				return error;
		}
		if (dev->poller)
			input_dev_poller_start(dev->poller);
	}

	dev->inhibited = false;

	scoped_guard(spinlock_irq, &dev->event_lock)
		input_dev_toggle(dev, true);

	return 0;
}

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

	guard(spinlock_irq)(&input_dev->event_lock);

	/*
	 * Keys that are pressed now are unlikely to be
	 * still pressed when we resume.
	 */
	if (input_dev_release_keys(input_dev))
		input_handle_event(input_dev, EV_SYN, SYN_REPORT, 1);

	/* Turn off LEDs and sounds, if any are active. */
	input_dev_toggle(input_dev, false);

	return 0;
}

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

	guard(spinlock_irq)(&input_dev->event_lock);

	/* Restore state of LEDs and sounds, if any were active. */
	input_dev_toggle(input_dev, true);

	return 0;
}

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

	guard(spinlock_irq)(&input_dev->event_lock);

	/*
	 * Keys that are pressed now are unlikely to be
	 * still pressed when we resume.
	 */
	if (input_dev_release_keys(input_dev))
		input_handle_event(input_dev, EV_SYN, SYN_REPORT, 1);

	return 0;
}

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

	guard(spinlock_irq)(&input_dev->event_lock);

	/* Turn off LEDs and sounds, if any are active. */
	input_dev_toggle(input_dev, false);

	return 0;
}

static const struct dev_pm_ops input_dev_pm_ops = {
	.suspend	= input_dev_suspend,
	.resume		= input_dev_resume,
	.freeze		= input_dev_freeze,
	.poweroff	= input_dev_poweroff,
	.restore	= input_dev_resume,
};

static const struct device_type input_dev_type = {
	.groups		= input_dev_attr_groups,
	.release	= input_dev_release,
	.uevent		= input_dev_uevent,
	.pm		= pm_sleep_ptr(&input_dev_pm_ops),
};

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

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

/**
 * input_allocate_device - allocate memory for new input device
 *
 * Returns prepared struct input_dev or %NULL.
 *
 * NOTE: Use input_free_device() to free devices that have not been
 * registered; input_unregister_device() should be used for already
 * registered devices.
 */
struct input_dev *input_allocate_device(void)
{
	static atomic_t input_no = ATOMIC_INIT(-1);
	struct input_dev *dev;

	dev = kzalloc_obj(*dev);
	if (!dev)
		return NULL;

	/*
	 * Start with space for SYN_REPORT + 7 EV_KEY/EV_MSC events + 2 spare,
	 * see input_estimate_events_per_packet(). We will tune the number
	 * when we register the device.
	 */
	dev->max_vals = 10;
	dev->vals = kzalloc_objs(*dev->vals, dev->max_vals);
	if (!dev->vals) {
		kfree(dev);
		return NULL;
	}

	mutex_init(&dev->mutex);
	spin_lock_init(&dev->event_lock);
	timer_setup(&dev->timer, NULL, 0);
	INIT_LIST_HEAD(&dev->h_list);
	INIT_LIST_HEAD(&dev->node);

	dev->dev.type = &input_dev_type;
	dev->dev.class = &input_class;
	device_initialize(&dev->dev);
	/*
	 * From this point on we can no longer simply "kfree(dev)", we need
	 * to use input_free_device() so that device core properly frees its
	 * resources associated with the input device.
	 */

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

	__module_get(THIS_MODULE);

	return dev;
}
EXPORT_SYMBOL(input_allocate_device);

struct input_devres {
	struct input_dev *input;
};

static int devm_input_device_match(struct device *dev, void *res, void *data)
{
	struct input_devres *devres = res;

	return devres->input == data;
}

static void devm_input_device_release(struct device *dev, void *res)
{
	struct input_devres *devres = res;
	struct input_dev *input = devres->input;

	dev_dbg(dev, "%s: dropping reference to %s\n",
		__func__, dev_name(&input->dev));
	input_put_device(input);
}

/**
 * devm_input_allocate_device - allocate managed input device
 * @dev: device owning the input device being created
 *
 * Returns prepared struct input_dev or %NULL.
 *
 * Managed input devices do not need to be explicitly unregistered or
 * freed as it will be done automatically when owner device unbinds from
 * its driver (or binding fails). Once managed input device is allocated,
 * it is ready to be set up and registered in the same fashion as regular
 * input device. There are no special devm_input_device_[un]register()
 * variants, regular ones work with both managed and unmanaged devices,
 * should you need them. In most cases however, managed input device need
 * not be explicitly unregistered or freed.
 *
 * NOTE: the owner device is set up as parent of input device and users
 * should not override it.
 */
struct input_dev *devm_input_allocate_device(struct device *dev)
{
	struct input_dev *input;
	struct input_devres *devres;

	devres = devres_alloc(devm_input_device_release,
			      sizeof(*devres), GFP_KERNEL);
	if (!devres)
		return NULL;

	input = input_allocate_device();
	if (!input) {
		devres_free(devres);
		return NULL;
	}

	input->dev.parent = dev;
	input->devres_managed = true;

	devres->input = input;
	devres_add(dev, devres);

	return input;
}
EXPORT_SYMBOL(devm_input_allocate_device);

/**
 * input_free_device - free memory occupied by input_dev structure
 * @dev: input device to free
 *
 * This function should only be used if input_register_device()
 * was not called yet or if it failed. Once device was registered
 * use input_unregister_device() and memory will be freed once last
 * reference to the device is dropped.
 *
 * Device should be allocated by input_allocate_device().
 *
 * NOTE: If there are references to the input device then memory
 * will not be freed until last reference is dropped.
 */
void input_free_device(struct input_dev *dev)
{
	if (dev) {
		if (dev->devres_managed)
			WARN_ON(devres_destroy(dev->dev.parent,
						devm_input_device_release,
						devm_input_device_match,
						dev));
		input_put_device(dev);
	}
}
EXPORT_SYMBOL(input_free_device);

/**
 * input_set_timestamp - set timestamp for input events
 * @dev: input device to set timestamp for
 * @timestamp: the time at which the event has occurred
 *   in CLOCK_MONOTONIC
 *
 * This function is intended to provide to the input system a more
 * accurate time of when an event actually occurred. The driver should
 * call this function as soon as a timestamp is acquired ensuring
 * clock conversions in input_set_timestamp are done correctly.
 *
 * The system entering suspend state between timestamp acquisition and
 * calling input_set_timestamp can result in inaccurate conversions.
 */
void input_set_timestamp(struct input_dev *dev, ktime_t timestamp)
{
	dev->timestamp[INPUT_CLK_MONO] = timestamp;
	dev->timestamp[INPUT_CLK_REAL] = ktime_mono_to_real(timestamp);
	dev->timestamp[INPUT_CLK_BOOT] = ktime_mono_to_any(timestamp,
							   TK_OFFS_BOOT);
}
EXPORT_SYMBOL(input_set_timestamp);

/**
 * input_get_timestamp - get timestamp for input events
 * @dev: input device to get timestamp from
 *
 * A valid timestamp is a timestamp of non-zero value.
 */
ktime_t *input_get_timestamp(struct input_dev *dev)
{
	const ktime_t invalid_timestamp = ktime_set(0, 0);

	if (!ktime_compare(dev->timestamp[INPUT_CLK_MONO], invalid_timestamp))
		input_set_timestamp(dev, ktime_get());

	return dev->timestamp;
}
EXPORT_SYMBOL(input_get_timestamp);

/**
 * input_set_capability - mark device as capable of a certain event
 * @dev: device that is capable of emitting or accepting event
 * @type: type of the event (EV_KEY, EV_REL, etc...)
 * @code: event code
 *
 * In addition to setting up corresponding bit in appropriate capability
 * bitmap the function also adjusts dev->evbit.
 */
void input_set_capability(struct input_dev *dev, unsigned int type, unsigned int code)
{
	if (type < EV_CNT && input_max_code[type] &&
	    code > input_max_code[type]) {
		pr_err("%s: invalid code %u for type %u\n", __func__, code,
		       type);
		dump_stack();
		return;
	}

	switch (type) {
	case EV_KEY:
		__set_bit(code, dev->keybit);
		break;

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

	case EV_ABS:
		input_alloc_absinfo(dev);
		__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("%s: unknown type %u (code %u)\n", __func__, 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 */

	if (test_bit(EV_ABS, dev->evbit))
		for_each_set_bit(i, dev->absbit, ABS_CNT)
			events += input_is_mt_axis(i) ? mt_slots : 1;

	if (test_bit(EV_REL, dev->evbit))
		events += bitmap_weight(dev->relbit, REL_CNT);

	/* 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);
}

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

	input_disconnect_device(dev);

	scoped_guard(mutex, &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));

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

		input_wakeup_procfs_readers();
	}

	device_del(&dev->dev);
}

static void devm_input_device_unregister(struct device *dev, void *res)
{
	struct input_devres *devres = res;
	struct input_dev *input = devres->input;

	dev_dbg(dev, "%s: unregistering device %s\n",
		__func__, dev_name(&input->dev));
	__input_unregister_device(input);
}

/*
 * 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(struct timer_list *t)
{
	struct input_dev *dev = timer_container_of(dev, t, timer);

	guard(spinlock_irqsave)(&dev->event_lock);

	if (!dev->inhibited &&
	    test_bit(dev->repeat_key, dev->key) &&
	    is_event_supported(dev->repeat_key, dev->keybit, KEY_MAX)) {

		input_set_timestamp(dev, ktime_get());
		input_handle_event(dev, EV_KEY, dev->repeat_key, 2);
		input_handle_event(dev, EV_SYN, SYN_REPORT, 1);

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

/**
 * input_enable_softrepeat - enable software autorepeat
 * @dev: input device
 * @delay: repeat delay
 * @period: repeat period
 *
 * Enable software autorepeat on the input device.
 */
void input_enable_softrepeat(struct input_dev *dev, int delay, int period)
{
	dev->timer.function = input_repeat_key;
	dev->rep[REP_DELAY] = delay;
	dev->rep[REP_PERIOD] = period;
}
EXPORT_SYMBOL(input_enable_softrepeat);

bool input_device_enabled(struct input_dev *dev)
{
	lockdep_assert_held(&dev->mutex);

	return !dev->inhibited && dev->users > 0;
}
EXPORT_SYMBOL_GPL(input_device_enabled);

static int input_device_tune_vals(struct input_dev *dev)
{
	struct input_value *vals;
	unsigned int packet_size;
	unsigned int max_vals;

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

	max_vals = dev->hint_events_per_packet + 2;
	if (dev->max_vals >= max_vals)
		return 0;

	vals = kcalloc(max_vals, sizeof(*vals), GFP_KERNEL);
	if (!vals)
		return -ENOMEM;

	scoped_guard(spinlock_irq, &dev->event_lock) {
		dev->max_vals = max_vals;
		swap(dev->vals, vals);
	}

	/* Because of swap() above, this frees the old vals memory */
	kfree(vals);

	return 0;
}

/**
 * input_register_device - register device with input core
 * @dev: device to be registered
 *
 * This function registers device with input core. The device must be
 * allocated with input_allocate_device() and all it's capabilities
 * set up before registering.
 * If function fails the device must be freed with input_free_device().
 * Once device has been successfully registered it can be unregistered
 * with input_unregister_device(); input_free_device() should not be
 * called in this case.
 *
 * Note that this function is also used to register managed input devices
 * (ones allocated with devm_input_allocate_device()). Such managed input
 * devices need not be explicitly unregistered or freed, their tear down
 * is controlled by the devres infrastructure. It is also worth noting
 * that tear down of managed input devices is internally a 2-step process:
 * registered managed input device is first unregistered, but stays in
 * memory and can still handle input_event() calls (although events will
 * not be delivered anywhere). The freeing of managed input device will
 * happen later, when devres stack is unwound to the point where device
 * allocation was made.
 */
int input_register_device(struct input_dev *dev)
{
	struct input_devres *devres = NULL;
	struct input_handler *handler;
	const char *path;
	int error;

	if (test_bit(EV_ABS, dev->evbit) && !dev->absinfo) {
		dev_err(&dev->dev,
			"Absolute device without dev->absinfo, refusing to register\n");
		return -EINVAL;
	}

	if (dev->devres_managed) {
		devres = devres_alloc(devm_input_device_unregister,
				      sizeof(*devres), GFP_KERNEL);
		if (!devres)
			return -ENOMEM;

		devres->input = dev;
	}

	/* 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);

	error = input_device_tune_vals(dev);
	if (error)
		goto err_devres_free;

	/*
	 * 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.
	 */
	if (!dev->rep[REP_DELAY] && !dev->rep[REP_PERIOD])
		input_enable_softrepeat(dev, 250, 33);

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

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

	if (dev->poller)
		input_dev_poller_finalize(dev->poller);

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

	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 = -EINTR;
	scoped_cond_guard(mutex_intr, goto err_device_del, &input_mutex) {
		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();
	}

	if (dev->devres_managed) {
		dev_dbg(dev->dev.parent, "%s: registering %s with devres.\n",
			__func__, dev_name(&dev->dev));
		devres_add(dev->dev.parent, devres);
	}
	return 0;

err_device_del:
	device_del(&dev->dev);
err_devres_free:
	devres_free(devres);
	return error;
}
EXPORT_SYMBOL(input_register_device);

/**
 * input_unregister_device - unregister previously registered device
 * @dev: device to be unregistered
 *
 * This function unregisters an input device. Once device is unregistered
 * the caller should not try to access it as it may get freed at any moment.
 */
void input_unregister_device(struct input_dev *dev)
{
	if (dev->devres_managed) {
		WARN_ON(devres_destroy(dev->dev.parent,
					devm_input_device_unregister,
					devm_input_device_match,
					dev));
		__input_unregister_device(dev);
		/*
		 * We do not do input_put_device() here because it will be done
		 * when 2nd devres fires up.
		 */
	} else {
		__input_unregister_device(dev);
		input_put_device(dev);
	}
}
EXPORT_SYMBOL(input_unregister_device);

static int input_handler_check_methods(const struct input_handler *handler)
{
	int count = 0;

	if (handler->filter)
		count++;
	if (handler->events)
		count++;
	if (handler->event)
		count++;

	if (count > 1) {
		pr_err("%s: only one event processing method can be defined (%s)\n",
		       __func__, handler->name);
		return -EINVAL;
	}

	return 0;
}

/**
 * input_register_handler - register a new input handler
 * @handler: handler to be registered
 *
 * This function registers a new input handler (interface) for input
 * devices in the system and attaches it to all input devices that
 * are compatible with the handler.
 */
int input_register_handler(struct input_handler *handler)
{
	struct input_dev *dev;
	int error;

	error = input_handler_check_methods(handler);
	if (error)
		return error;

	scoped_cond_guard(mutex_intr, return -EINTR, &input_mutex) {
		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();
	}

	return 0;
}
EXPORT_SYMBOL(input_register_handler);

/**
 * input_unregister_handler - unregisters an input handler
 * @handler: handler to be unregistered
 *
 * This function disconnects a handler from its input devices and
 * removes it from lists of known handlers.
 */
void input_unregister_handler(struct input_handler *handler)
{
	struct input_handle *handle, *next;

	guard(mutex)(&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();
}
EXPORT_SYMBOL(input_unregister_handler);

/**
 * input_handler_for_each_handle - handle iterator
 * @handler: input handler to iterate
 * @data: data for the callback
 * @fn: function to be called for each handle
 *
 * Iterate over @bus's list of devices, and call @fn for each, passing
 * it @data and stop when @fn returns a non-zero value. The function is
 * using RCU to traverse the list and therefore may be using in atomic
 * contexts. The @fn callback is invoked from RCU critical section and
 * thus must not sleep.
 */
int input_handler_for_each_handle(struct input_handler *handler, void *data,
				  int (*fn)(struct input_handle *, void *))
{
	struct input_handle *handle;
	int retval;

	guard(rcu)();

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

	return 0;
}
EXPORT_SYMBOL(input_handler_for_each_handle);

/*
 * An implementation of input_handle's handle_events() method that simply
 * invokes handler->event() method for each event one by one.
 */
static unsigned int input_handle_events_default(struct input_handle *handle,
						struct input_value *vals,
						unsigned int count)
{
	struct input_handler *handler = handle->handler;
	struct input_value *v;

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

	return count;
}

/*
 * An implementation of input_handle's handle_events() method that invokes
 * handler->filter() method for each event one by one and removes events
 * that were filtered out from the "vals" array.
 */
static unsigned int input_handle_events_filter(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(handle, v->type, v->code, v->value))
			continue;
		if (end != v)
			*end = *v;
		end++;
	}

	return end - vals;
}

/*
 * An implementation of input_handle's handle_events() method that does nothing.
 */
static unsigned int input_handle_events_null(struct input_handle *handle,
					     struct input_value *vals,
					     unsigned int count)
{
	return count;
}

/*
 * Sets up appropriate handle->event_handler based on the input_handler
 * associated with the handle.
 */
static void input_handle_setup_event_handler(struct input_handle *handle)
{
	struct input_handler *handler = handle->handler;

	if (handler->filter)
		handle->handle_events = input_handle_events_filter;
	else if (handler->event)
		handle->handle_events = input_handle_events_default;
	else if (handler->events)
		handle->handle_events = handler->events;
	else
		handle->handle_events = input_handle_events_null;
}

/**
 * input_register_handle - register a new input handle
 * @handle: handle to register
 *
 * This function puts a new input handle onto device's
 * and handler's lists so that events can flow through
 * it once it is opened using input_open_device().
 *
 * This function is supposed to be called from handler's
 * connect() method.
 */
int input_register_handle(struct input_handle *handle)
{
	struct input_handler *handler = handle->handler;
	struct input_dev *dev = handle->dev;

	input_handle_setup_event_handler(handle);
	/*
	 * We take dev->mutex here to prevent race with
	 * input_release_device().
	 */
	scoped_cond_guard(mutex_intr, return -EINTR, &dev->mutex) {
		/*
		 * 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);
	}

	/*
	 * 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);

/**
 * input_unregister_handle - unregister an input handle
 * @handle: handle to unregister
 *
 * This function removes input handle from device's
 * and handler's lists.
 *
 * This function is supposed to be called from handler's
 * disconnect() method.
 */
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().
	 */
	scoped_guard(mutex, &dev->mutex)
		list_del_rcu(&handle->d_node);

	synchronize_rcu();
}
EXPORT_SYMBOL(input_unregister_handle);

/**
 * input_get_new_minor - allocates a new input minor number
 * @legacy_base: beginning or the legacy range to be searched
 * @legacy_num: size of legacy range
 * @allow_dynamic: whether we can also take ID from the dynamic range
 *
 * This function allocates a new device minor for from input major namespace.
 * Caller can request legacy minor by specifying @legacy_base and @legacy_num
 * parameters and whether ID can be allocated from dynamic range if there are
 * no free IDs in legacy range.
 */
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_alloc_range(&input_ida, legacy_base,
					    legacy_base + legacy_num - 1,
					    GFP_KERNEL);
		if (minor >= 0 || !allow_dynamic)
			return minor;
	}

	return ida_alloc_range(&input_ida, INPUT_FIRST_DYNAMIC_DEV,
			       INPUT_MAX_CHAR_DEVICES - 1, GFP_KERNEL);
}
EXPORT_SYMBOL(input_get_new_minor);

/**
 * input_free_minor - release previously allocated minor
 * @minor: minor to be released
 *
 * This function releases previously allocated input minor so that it can be
 * reused later.
 */
void input_free_minor(unsigned int minor)
{
	ida_free(&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);