input.c

linux 内核源代码

/*
 * 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.
 */

#include <linux/init.h>
#include <linux/input.h>
#include <linux/module.h>
#include <linux/random.h>
#include <linux/major.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/poll.h>
#include <linux/device.h>
#include <linux/mutex.h>
#include <linux/rcupdate.h>

MODULE_AUTHOR("Vojtech Pavlik <[e-mail]>");
MODULE_DESCRIPTION("Input core");
MODULE_LICENSE("GPL");

#define INPUT_DEVICES	256

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 struct input_handler *input_table[8];

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;
}

/*
 * Pass event through all open handles. This function is called with
 * dev->event_lock held and interrupts disabled.
 */
static void input_pass_event(struct input_dev *dev,
			     unsigned int type, unsigned int code, int value)
{
	struct input_handle *handle;

	rcu_read_lock();

	handle = rcu_dereference(dev->grab);
	if (handle)
		handle->handler->event(handle, type, code, value);
	else
		list_for_each_entry_rcu(handle, &dev->h_list, d_node)
			if (handle->open)
				handle->handler->event(handle,
							type, code, value);
	rcu_read_unlock();
}

/*
 * 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)) {

		input_pass_event(dev, EV_KEY, dev->repeat_key, 2);

		if (dev->sync) {
			/*
			 * Only send SYN_REPORT if we are not in a middle
			 * of driver parsing a new hardware packet.
			 * Otherwise assume that the driver will send
			 * SYN_REPORT once it's done.
			 */
			input_pass_event(dev, EV_SYN, SYN_REPORT, 1);
		}

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

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

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]));
	}
}

#define INPUT_IGNORE_EVENT	0
#define INPUT_PASS_TO_HANDLERS	1
#define INPUT_PASS_TO_DEVICE	2
#define INPUT_PASS_TO_ALL	(INPUT_PASS_TO_HANDLERS | INPUT_PASS_TO_DEVICE)

static void input_handle_event(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:
			if (!dev->sync) {
				dev->sync = 1;
				disposition = INPUT_PASS_TO_HANDLERS;
			}
			break;
		}
		break;

	case EV_KEY:
		if (is_event_supported(code, dev->keybit, KEY_MAX) &&
		    !!test_bit(code, dev->key) != value) {

			if (value != 2) {
				__change_bit(code, dev->key);
				if (value)
					input_start_autorepeat(dev, code);
			}

			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)) {

			value = input_defuzz_abs_event(value,
					dev->abs[code], dev->absfuzz[code]);

			if (dev->abs[code] != value) {
				dev->abs[code] = value;
				disposition = INPUT_PASS_TO_HANDLERS;
			}
		}
		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;
	}

	if (type != EV_SYN)
		dev->sync = 0;

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

	if (disposition & INPUT_PASS_TO_HANDLERS)
		input_pass_event(dev, 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. See also input_inject_event().
 */

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

/**
 * 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;
	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);
	synchronize_rcu();

 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);
	}
}

/**
 * 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;

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

/**
 * 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;

	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);

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

	/*
	 * 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 = 1;
	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.
	 */
	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_bit(code, dev->key)) {
				input_pass_event(dev, EV_KEY, code, 0);
			}
		}
		input_pass_event(dev, EV_SYN, SYN_REPORT, 1);
	}

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

	spin_unlock_irq(&dev->event_lock);
}

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

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

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

static int input_default_getkeycode(struct input_dev *dev,
				    int scancode, int *keycode)
{
	if (!dev->keycodesize)
		return -EINVAL;

	if (scancode < 0 || scancode >= dev->keycodemax)
		return -EINVAL;

	*keycode = input_fetch_keycode(dev, scancode);

	return 0;