xref: /linux/drivers/input/input.c (revision 48c36c8f9a3e881953bb72deb55623a53795a684)
1 /*
2  * The input core
3  *
4  * Copyright (c) 1999-2002 Vojtech Pavlik
5  */
6 
7 /*
8  * This program is free software; you can redistribute it and/or modify it
9  * under the terms of the GNU General Public License version 2 as published by
10  * the Free Software Foundation.
11  */
12 
13 #include <linux/init.h>
14 #include <linux/types.h>
15 #include <linux/input.h>
16 #include <linux/module.h>
17 #include <linux/slab.h>
18 #include <linux/random.h>
19 #include <linux/major.h>
20 #include <linux/proc_fs.h>
21 #include <linux/sched.h>
22 #include <linux/seq_file.h>
23 #include <linux/poll.h>
24 #include <linux/device.h>
25 #include <linux/mutex.h>
26 #include <linux/rcupdate.h>
27 #include "input-compat.h"
28 
29 MODULE_AUTHOR("Vojtech Pavlik <vojtech@suse.cz>");
30 MODULE_DESCRIPTION("Input core");
31 MODULE_LICENSE("GPL");
32 
33 #define INPUT_DEVICES	256
34 
35 static LIST_HEAD(input_dev_list);
36 static LIST_HEAD(input_handler_list);
37 
38 /*
39  * input_mutex protects access to both input_dev_list and input_handler_list.
40  * This also causes input_[un]register_device and input_[un]register_handler
41  * be mutually exclusive which simplifies locking in drivers implementing
42  * input handlers.
43  */
44 static DEFINE_MUTEX(input_mutex);
45 
46 static struct input_handler *input_table[8];
47 
48 static inline int is_event_supported(unsigned int code,
49 				     unsigned long *bm, unsigned int max)
50 {
51 	return code <= max && test_bit(code, bm);
52 }
53 
54 static int input_defuzz_abs_event(int value, int old_val, int fuzz)
55 {
56 	if (fuzz) {
57 		if (value > old_val - fuzz / 2 && value < old_val + fuzz / 2)
58 			return old_val;
59 
60 		if (value > old_val - fuzz && value < old_val + fuzz)
61 			return (old_val * 3 + value) / 4;
62 
63 		if (value > old_val - fuzz * 2 && value < old_val + fuzz * 2)
64 			return (old_val + value) / 2;
65 	}
66 
67 	return value;
68 }
69 
70 /*
71  * Pass event first through all filters and then, if event has not been
72  * filtered out, through all open handles. This function is called with
73  * dev->event_lock held and interrupts disabled.
74  */
75 static void input_pass_event(struct input_dev *dev,
76 			     struct input_handler *src_handler,
77 			     unsigned int type, unsigned int code, int value)
78 {
79 	struct input_handler *handler;
80 	struct input_handle *handle;
81 
82 	rcu_read_lock();
83 
84 	handle = rcu_dereference(dev->grab);
85 	if (handle)
86 		handle->handler->event(handle, type, code, value);
87 	else {
88 		bool filtered = false;
89 
90 		list_for_each_entry_rcu(handle, &dev->h_list, d_node) {
91 			if (!handle->open)
92 				continue;
93 
94 			handler = handle->handler;
95 
96 			/*
97 			 * If this is the handler that injected this
98 			 * particular event we want to skip it to avoid
99 			 * filters firing again and again.
100 			 */
101 			if (handler == src_handler)
102 				continue;
103 
104 			if (!handler->filter) {
105 				if (filtered)
106 					break;
107 
108 				handler->event(handle, type, code, value);
109 
110 			} else if (handler->filter(handle, type, code, value))
111 				filtered = true;
112 		}
113 	}
114 
115 	rcu_read_unlock();
116 }
117 
118 /*
119  * Generate software autorepeat event. Note that we take
120  * dev->event_lock here to avoid racing with input_event
121  * which may cause keys get "stuck".
122  */
123 static void input_repeat_key(unsigned long data)
124 {
125 	struct input_dev *dev = (void *) data;
126 	unsigned long flags;
127 
128 	spin_lock_irqsave(&dev->event_lock, flags);
129 
130 	if (test_bit(dev->repeat_key, dev->key) &&
131 	    is_event_supported(dev->repeat_key, dev->keybit, KEY_MAX)) {
132 
133 		input_pass_event(dev, NULL, EV_KEY, dev->repeat_key, 2);
134 
135 		if (dev->sync) {
136 			/*
137 			 * Only send SYN_REPORT if we are not in a middle
138 			 * of driver parsing a new hardware packet.
139 			 * Otherwise assume that the driver will send
140 			 * SYN_REPORT once it's done.
141 			 */
142 			input_pass_event(dev, NULL, EV_SYN, SYN_REPORT, 1);
143 		}
144 
145 		if (dev->rep[REP_PERIOD])
146 			mod_timer(&dev->timer, jiffies +
147 					msecs_to_jiffies(dev->rep[REP_PERIOD]));
148 	}
149 
150 	spin_unlock_irqrestore(&dev->event_lock, flags);
151 }
152 
153 static void input_start_autorepeat(struct input_dev *dev, int code)
154 {
155 	if (test_bit(EV_REP, dev->evbit) &&
156 	    dev->rep[REP_PERIOD] && dev->rep[REP_DELAY] &&
157 	    dev->timer.data) {
158 		dev->repeat_key = code;
159 		mod_timer(&dev->timer,
160 			  jiffies + msecs_to_jiffies(dev->rep[REP_DELAY]));
161 	}
162 }
163 
164 static void input_stop_autorepeat(struct input_dev *dev)
165 {
166 	del_timer(&dev->timer);
167 }
168 
169 #define INPUT_IGNORE_EVENT	0
170 #define INPUT_PASS_TO_HANDLERS	1
171 #define INPUT_PASS_TO_DEVICE	2
172 #define INPUT_PASS_TO_ALL	(INPUT_PASS_TO_HANDLERS | INPUT_PASS_TO_DEVICE)
173 
174 static int input_handle_abs_event(struct input_dev *dev,
175 				  struct input_handler *src_handler,
176 				  unsigned int code, int *pval)
177 {
178 	bool is_mt_event;
179 	int *pold;
180 
181 	if (code == ABS_MT_SLOT) {
182 		/*
183 		 * "Stage" the event; we'll flush it later, when we
184 		 * get actual touch data.
185 		 */
186 		if (*pval >= 0 && *pval < dev->mtsize)
187 			dev->slot = *pval;
188 
189 		return INPUT_IGNORE_EVENT;
190 	}
191 
192 	is_mt_event = code >= ABS_MT_FIRST && code <= ABS_MT_LAST;
193 
194 	if (!is_mt_event) {
195 		pold = &dev->absinfo[code].value;
196 	} else if (dev->mt) {
197 		struct input_mt_slot *mtslot = &dev->mt[dev->slot];
198 		pold = &mtslot->abs[code - ABS_MT_FIRST];
199 	} else {
200 		/*
201 		 * Bypass filtering for multi-touch events when
202 		 * not employing slots.
203 		 */
204 		pold = NULL;
205 	}
206 
207 	if (pold) {
208 		*pval = input_defuzz_abs_event(*pval, *pold,
209 						dev->absinfo[code].fuzz);
210 		if (*pold == *pval)
211 			return INPUT_IGNORE_EVENT;
212 
213 		*pold = *pval;
214 	}
215 
216 	/* Flush pending "slot" event */
217 	if (is_mt_event && dev->slot != input_abs_get_val(dev, ABS_MT_SLOT)) {
218 		input_abs_set_val(dev, ABS_MT_SLOT, dev->slot);
219 		input_pass_event(dev, src_handler,
220 				 EV_ABS, ABS_MT_SLOT, dev->slot);
221 	}
222 
223 	return INPUT_PASS_TO_HANDLERS;
224 }
225 
226 static void input_handle_event(struct input_dev *dev,
227 			       struct input_handler *src_handler,
228 			       unsigned int type, unsigned int code, int value)
229 {
230 	int disposition = INPUT_IGNORE_EVENT;
231 
232 	switch (type) {
233 
234 	case EV_SYN:
235 		switch (code) {
236 		case SYN_CONFIG:
237 			disposition = INPUT_PASS_TO_ALL;
238 			break;
239 
240 		case SYN_REPORT:
241 			if (!dev->sync) {
242 				dev->sync = true;
243 				disposition = INPUT_PASS_TO_HANDLERS;
244 			}
245 			break;
246 		case SYN_MT_REPORT:
247 			dev->sync = false;
248 			disposition = INPUT_PASS_TO_HANDLERS;
249 			break;
250 		}
251 		break;
252 
253 	case EV_KEY:
254 		if (is_event_supported(code, dev->keybit, KEY_MAX) &&
255 		    !!test_bit(code, dev->key) != value) {
256 
257 			if (value != 2) {
258 				__change_bit(code, dev->key);
259 				if (value)
260 					input_start_autorepeat(dev, code);
261 				else
262 					input_stop_autorepeat(dev);
263 			}
264 
265 			disposition = INPUT_PASS_TO_HANDLERS;
266 		}
267 		break;
268 
269 	case EV_SW:
270 		if (is_event_supported(code, dev->swbit, SW_MAX) &&
271 		    !!test_bit(code, dev->sw) != value) {
272 
273 			__change_bit(code, dev->sw);
274 			disposition = INPUT_PASS_TO_HANDLERS;
275 		}
276 		break;
277 
278 	case EV_ABS:
279 		if (is_event_supported(code, dev->absbit, ABS_MAX))
280 			disposition = input_handle_abs_event(dev, src_handler,
281 							     code, &value);
282 
283 		break;
284 
285 	case EV_REL:
286 		if (is_event_supported(code, dev->relbit, REL_MAX) && value)
287 			disposition = INPUT_PASS_TO_HANDLERS;
288 
289 		break;
290 
291 	case EV_MSC:
292 		if (is_event_supported(code, dev->mscbit, MSC_MAX))
293 			disposition = INPUT_PASS_TO_ALL;
294 
295 		break;
296 
297 	case EV_LED:
298 		if (is_event_supported(code, dev->ledbit, LED_MAX) &&
299 		    !!test_bit(code, dev->led) != value) {
300 
301 			__change_bit(code, dev->led);
302 			disposition = INPUT_PASS_TO_ALL;
303 		}
304 		break;
305 
306 	case EV_SND:
307 		if (is_event_supported(code, dev->sndbit, SND_MAX)) {
308 
309 			if (!!test_bit(code, dev->snd) != !!value)
310 				__change_bit(code, dev->snd);
311 			disposition = INPUT_PASS_TO_ALL;
312 		}
313 		break;
314 
315 	case EV_REP:
316 		if (code <= REP_MAX && value >= 0 && dev->rep[code] != value) {
317 			dev->rep[code] = value;
318 			disposition = INPUT_PASS_TO_ALL;
319 		}
320 		break;
321 
322 	case EV_FF:
323 		if (value >= 0)
324 			disposition = INPUT_PASS_TO_ALL;
325 		break;
326 
327 	case EV_PWR:
328 		disposition = INPUT_PASS_TO_ALL;
329 		break;
330 	}
331 
332 	if (disposition != INPUT_IGNORE_EVENT && type != EV_SYN)
333 		dev->sync = false;
334 
335 	if ((disposition & INPUT_PASS_TO_DEVICE) && dev->event)
336 		dev->event(dev, type, code, value);
337 
338 	if (disposition & INPUT_PASS_TO_HANDLERS)
339 		input_pass_event(dev, src_handler, type, code, value);
340 }
341 
342 /**
343  * input_event() - report new input event
344  * @dev: device that generated the event
345  * @type: type of the event
346  * @code: event code
347  * @value: value of the event
348  *
349  * This function should be used by drivers implementing various input
350  * devices to report input events. See also input_inject_event().
351  *
352  * NOTE: input_event() may be safely used right after input device was
353  * allocated with input_allocate_device(), even before it is registered
354  * with input_register_device(), but the event will not reach any of the
355  * input handlers. Such early invocation of input_event() may be used
356  * to 'seed' initial state of a switch or initial position of absolute
357  * axis, etc.
358  */
359 void input_event(struct input_dev *dev,
360 		 unsigned int type, unsigned int code, int value)
361 {
362 	unsigned long flags;
363 
364 	if (is_event_supported(type, dev->evbit, EV_MAX)) {
365 
366 		spin_lock_irqsave(&dev->event_lock, flags);
367 		add_input_randomness(type, code, value);
368 		input_handle_event(dev, NULL, type, code, value);
369 		spin_unlock_irqrestore(&dev->event_lock, flags);
370 	}
371 }
372 EXPORT_SYMBOL(input_event);
373 
374 /**
375  * input_inject_event() - send input event from input handler
376  * @handle: input handle to send event through
377  * @type: type of the event
378  * @code: event code
379  * @value: value of the event
380  *
381  * Similar to input_event() but will ignore event if device is
382  * "grabbed" and handle injecting event is not the one that owns
383  * the device.
384  */
385 void input_inject_event(struct input_handle *handle,
386 			unsigned int type, unsigned int code, int value)
387 {
388 	struct input_dev *dev = handle->dev;
389 	struct input_handle *grab;
390 	unsigned long flags;
391 
392 	if (is_event_supported(type, dev->evbit, EV_MAX)) {
393 		spin_lock_irqsave(&dev->event_lock, flags);
394 
395 		rcu_read_lock();
396 		grab = rcu_dereference(dev->grab);
397 		if (!grab || grab == handle)
398 			input_handle_event(dev, handle->handler,
399 					   type, code, value);
400 		rcu_read_unlock();
401 
402 		spin_unlock_irqrestore(&dev->event_lock, flags);
403 	}
404 }
405 EXPORT_SYMBOL(input_inject_event);
406 
407 /**
408  * input_alloc_absinfo - allocates array of input_absinfo structs
409  * @dev: the input device emitting absolute events
410  *
411  * If the absinfo struct the caller asked for is already allocated, this
412  * functions will not do anything.
413  */
414 void input_alloc_absinfo(struct input_dev *dev)
415 {
416 	if (!dev->absinfo)
417 		dev->absinfo = kcalloc(ABS_CNT, sizeof(struct input_absinfo),
418 					GFP_KERNEL);
419 
420 	WARN(!dev->absinfo, "%s(): kcalloc() failed?\n", __func__);
421 }
422 EXPORT_SYMBOL(input_alloc_absinfo);
423 
424 void input_set_abs_params(struct input_dev *dev, unsigned int axis,
425 			  int min, int max, int fuzz, int flat)
426 {
427 	struct input_absinfo *absinfo;
428 
429 	input_alloc_absinfo(dev);
430 	if (!dev->absinfo)
431 		return;
432 
433 	absinfo = &dev->absinfo[axis];
434 	absinfo->minimum = min;
435 	absinfo->maximum = max;
436 	absinfo->fuzz = fuzz;
437 	absinfo->flat = flat;
438 
439 	dev->absbit[BIT_WORD(axis)] |= BIT_MASK(axis);
440 }
441 EXPORT_SYMBOL(input_set_abs_params);
442 
443 
444 /**
445  * input_grab_device - grabs device for exclusive use
446  * @handle: input handle that wants to own the device
447  *
448  * When a device is grabbed by an input handle all events generated by
449  * the device are delivered only to this handle. Also events injected
450  * by other input handles are ignored while device is grabbed.
451  */
452 int input_grab_device(struct input_handle *handle)
453 {
454 	struct input_dev *dev = handle->dev;
455 	int retval;
456 
457 	retval = mutex_lock_interruptible(&dev->mutex);
458 	if (retval)
459 		return retval;
460 
461 	if (dev->grab) {
462 		retval = -EBUSY;
463 		goto out;
464 	}
465 
466 	rcu_assign_pointer(dev->grab, handle);
467 	synchronize_rcu();
468 
469  out:
470 	mutex_unlock(&dev->mutex);
471 	return retval;
472 }
473 EXPORT_SYMBOL(input_grab_device);
474 
475 static void __input_release_device(struct input_handle *handle)
476 {
477 	struct input_dev *dev = handle->dev;
478 
479 	if (dev->grab == handle) {
480 		rcu_assign_pointer(dev->grab, NULL);
481 		/* Make sure input_pass_event() notices that grab is gone */
482 		synchronize_rcu();
483 
484 		list_for_each_entry(handle, &dev->h_list, d_node)
485 			if (handle->open && handle->handler->start)
486 				handle->handler->start(handle);
487 	}
488 }
489 
490 /**
491  * input_release_device - release previously grabbed device
492  * @handle: input handle that owns the device
493  *
494  * Releases previously grabbed device so that other input handles can
495  * start receiving input events. Upon release all handlers attached
496  * to the device have their start() method called so they have a change
497  * to synchronize device state with the rest of the system.
498  */
499 void input_release_device(struct input_handle *handle)
500 {
501 	struct input_dev *dev = handle->dev;
502 
503 	mutex_lock(&dev->mutex);
504 	__input_release_device(handle);
505 	mutex_unlock(&dev->mutex);
506 }
507 EXPORT_SYMBOL(input_release_device);
508 
509 /**
510  * input_open_device - open input device
511  * @handle: handle through which device is being accessed
512  *
513  * This function should be called by input handlers when they
514  * want to start receive events from given input device.
515  */
516 int input_open_device(struct input_handle *handle)
517 {
518 	struct input_dev *dev = handle->dev;
519 	int retval;
520 
521 	retval = mutex_lock_interruptible(&dev->mutex);
522 	if (retval)
523 		return retval;
524 
525 	if (dev->going_away) {
526 		retval = -ENODEV;
527 		goto out;
528 	}
529 
530 	handle->open++;
531 
532 	if (!dev->users++ && dev->open)
533 		retval = dev->open(dev);
534 
535 	if (retval) {
536 		dev->users--;
537 		if (!--handle->open) {
538 			/*
539 			 * Make sure we are not delivering any more events
540 			 * through this handle
541 			 */
542 			synchronize_rcu();
543 		}
544 	}
545 
546  out:
547 	mutex_unlock(&dev->mutex);
548 	return retval;
549 }
550 EXPORT_SYMBOL(input_open_device);
551 
552 int input_flush_device(struct input_handle *handle, struct file *file)
553 {
554 	struct input_dev *dev = handle->dev;
555 	int retval;
556 
557 	retval = mutex_lock_interruptible(&dev->mutex);
558 	if (retval)
559 		return retval;
560 
561 	if (dev->flush)
562 		retval = dev->flush(dev, file);
563 
564 	mutex_unlock(&dev->mutex);
565 	return retval;
566 }
567 EXPORT_SYMBOL(input_flush_device);
568 
569 /**
570  * input_close_device - close input device
571  * @handle: handle through which device is being accessed
572  *
573  * This function should be called by input handlers when they
574  * want to stop receive events from given input device.
575  */
576 void input_close_device(struct input_handle *handle)
577 {
578 	struct input_dev *dev = handle->dev;
579 
580 	mutex_lock(&dev->mutex);
581 
582 	__input_release_device(handle);
583 
584 	if (!--dev->users && dev->close)
585 		dev->close(dev);
586 
587 	if (!--handle->open) {
588 		/*
589 		 * synchronize_rcu() makes sure that input_pass_event()
590 		 * completed and that no more input events are delivered
591 		 * through this handle
592 		 */
593 		synchronize_rcu();
594 	}
595 
596 	mutex_unlock(&dev->mutex);
597 }
598 EXPORT_SYMBOL(input_close_device);
599 
600 /*
601  * Simulate keyup events for all keys that are marked as pressed.
602  * The function must be called with dev->event_lock held.
603  */
604 static void input_dev_release_keys(struct input_dev *dev)
605 {
606 	int code;
607 
608 	if (is_event_supported(EV_KEY, dev->evbit, EV_MAX)) {
609 		for (code = 0; code <= KEY_MAX; code++) {
610 			if (is_event_supported(code, dev->keybit, KEY_MAX) &&
611 			    __test_and_clear_bit(code, dev->key)) {
612 				input_pass_event(dev, NULL, EV_KEY, code, 0);
613 			}
614 		}
615 		input_pass_event(dev, NULL, EV_SYN, SYN_REPORT, 1);
616 	}
617 }
618 
619 /*
620  * Prepare device for unregistering
621  */
622 static void input_disconnect_device(struct input_dev *dev)
623 {
624 	struct input_handle *handle;
625 
626 	/*
627 	 * Mark device as going away. Note that we take dev->mutex here
628 	 * not to protect access to dev->going_away but rather to ensure
629 	 * that there are no threads in the middle of input_open_device()
630 	 */
631 	mutex_lock(&dev->mutex);
632 	dev->going_away = true;
633 	mutex_unlock(&dev->mutex);
634 
635 	spin_lock_irq(&dev->event_lock);
636 
637 	/*
638 	 * Simulate keyup events for all pressed keys so that handlers
639 	 * are not left with "stuck" keys. The driver may continue
640 	 * generate events even after we done here but they will not
641 	 * reach any handlers.
642 	 */
643 	input_dev_release_keys(dev);
644 
645 	list_for_each_entry(handle, &dev->h_list, d_node)
646 		handle->open = 0;
647 
648 	spin_unlock_irq(&dev->event_lock);
649 }
650 
651 /**
652  * input_scancode_to_scalar() - converts scancode in &struct input_keymap_entry
653  * @ke: keymap entry containing scancode to be converted.
654  * @scancode: pointer to the location where converted scancode should
655  *	be stored.
656  *
657  * This function is used to convert scancode stored in &struct keymap_entry
658  * into scalar form understood by legacy keymap handling methods. These
659  * methods expect scancodes to be represented as 'unsigned int'.
660  */
661 int input_scancode_to_scalar(const struct input_keymap_entry *ke,
662 			     unsigned int *scancode)
663 {
664 	switch (ke->len) {
665 	case 1:
666 		*scancode = *((u8 *)ke->scancode);
667 		break;
668 
669 	case 2:
670 		*scancode = *((u16 *)ke->scancode);
671 		break;
672 
673 	case 4:
674 		*scancode = *((u32 *)ke->scancode);
675 		break;
676 
677 	default:
678 		return -EINVAL;
679 	}
680 
681 	return 0;
682 }
683 EXPORT_SYMBOL(input_scancode_to_scalar);
684 
685 /*
686  * Those routines handle the default case where no [gs]etkeycode() is
687  * defined. In this case, an array indexed by the scancode is used.
688  */
689 
690 static unsigned int input_fetch_keycode(struct input_dev *dev,
691 					unsigned int index)
692 {
693 	switch (dev->keycodesize) {
694 	case 1:
695 		return ((u8 *)dev->keycode)[index];
696 
697 	case 2:
698 		return ((u16 *)dev->keycode)[index];
699 
700 	default:
701 		return ((u32 *)dev->keycode)[index];
702 	}
703 }
704 
705 static int input_default_getkeycode(struct input_dev *dev,
706 				    struct input_keymap_entry *ke)
707 {
708 	unsigned int index;
709 	int error;
710 
711 	if (!dev->keycodesize)
712 		return -EINVAL;
713 
714 	if (ke->flags & INPUT_KEYMAP_BY_INDEX)
715 		index = ke->index;
716 	else {
717 		error = input_scancode_to_scalar(ke, &index);
718 		if (error)
719 			return error;
720 	}
721 
722 	if (index >= dev->keycodemax)
723 		return -EINVAL;
724 
725 	ke->keycode = input_fetch_keycode(dev, index);
726 	ke->index = index;
727 	ke->len = sizeof(index);
728 	memcpy(ke->scancode, &index, sizeof(index));
729 
730 	return 0;
731 }
732 
733 static int input_default_setkeycode(struct input_dev *dev,
734 				    const struct input_keymap_entry *ke,
735 				    unsigned int *old_keycode)
736 {
737 	unsigned int index;
738 	int error;
739 	int i;
740 
741 	if (!dev->keycodesize)
742 		return -EINVAL;
743 
744 	if (ke->flags & INPUT_KEYMAP_BY_INDEX) {
745 		index = ke->index;
746 	} else {
747 		error = input_scancode_to_scalar(ke, &index);
748 		if (error)
749 			return error;
750 	}
751 
752 	if (index >= dev->keycodemax)
753 		return -EINVAL;
754 
755 	if (dev->keycodesize < sizeof(ke->keycode) &&
756 			(ke->keycode >> (dev->keycodesize * 8)))
757 		return -EINVAL;
758 
759 	switch (dev->keycodesize) {
760 		case 1: {
761 			u8 *k = (u8 *)dev->keycode;
762 			*old_keycode = k[index];
763 			k[index] = ke->keycode;
764 			break;
765 		}
766 		case 2: {
767 			u16 *k = (u16 *)dev->keycode;
768 			*old_keycode = k[index];
769 			k[index] = ke->keycode;
770 			break;
771 		}
772 		default: {
773 			u32 *k = (u32 *)dev->keycode;
774 			*old_keycode = k[index];
775 			k[index] = ke->keycode;
776 			break;
777 		}
778 	}
779 
780 	__clear_bit(*old_keycode, dev->keybit);
781 	__set_bit(ke->keycode, dev->keybit);
782 
783 	for (i = 0; i < dev->keycodemax; i++) {
784 		if (input_fetch_keycode(dev, i) == *old_keycode) {
785 			__set_bit(*old_keycode, dev->keybit);
786 			break; /* Setting the bit twice is useless, so break */
787 		}
788 	}
789 
790 	return 0;
791 }
792 
793 /**
794  * input_get_keycode - retrieve keycode currently mapped to a given scancode
795  * @dev: input device which keymap is being queried
796  * @ke: keymap entry
797  *
798  * This function should be called by anyone interested in retrieving current
799  * keymap. Presently evdev handlers use it.
800  */
801 int input_get_keycode(struct input_dev *dev, struct input_keymap_entry *ke)
802 {
803 	unsigned long flags;
804 	int retval;
805 
806 	spin_lock_irqsave(&dev->event_lock, flags);
807 
808 	if (dev->getkeycode) {
809 		/*
810 		 * Support for legacy drivers, that don't implement the new
811 		 * ioctls
812 		 */
813 		u32 scancode = ke->index;
814 
815 		memcpy(ke->scancode, &scancode, sizeof(scancode));
816 		ke->len = sizeof(scancode);
817 		retval = dev->getkeycode(dev, scancode, &ke->keycode);
818 	} else {
819 		retval = dev->getkeycode_new(dev, ke);
820 	}
821 
822 	spin_unlock_irqrestore(&dev->event_lock, flags);
823 	return retval;
824 }
825 EXPORT_SYMBOL(input_get_keycode);
826 
827 /**
828  * input_set_keycode - attribute a keycode to a given scancode
829  * @dev: input device which keymap is being updated
830  * @ke: new keymap entry
831  *
832  * This function should be called by anyone needing to update current
833  * keymap. Presently keyboard and evdev handlers use it.
834  */
835 int input_set_keycode(struct input_dev *dev,
836 		      const struct input_keymap_entry *ke)
837 {
838 	unsigned long flags;
839 	unsigned int old_keycode;
840 	int retval;
841 
842 	if (ke->keycode > KEY_MAX)
843 		return -EINVAL;
844 
845 	spin_lock_irqsave(&dev->event_lock, flags);
846 
847 	if (dev->setkeycode) {
848 		/*
849 		 * Support for legacy drivers, that don't implement the new
850 		 * ioctls
851 		 */
852 		unsigned int scancode;
853 
854 		retval = input_scancode_to_scalar(ke, &scancode);
855 		if (retval)
856 			goto out;
857 
858 		/*
859 		 * We need to know the old scancode, in order to generate a
860 		 * keyup effect, if the set operation happens successfully
861 		 */
862 		if (!dev->getkeycode) {
863 			retval = -EINVAL;
864 			goto out;
865 		}
866 
867 		retval = dev->getkeycode(dev, scancode, &old_keycode);
868 		if (retval)
869 			goto out;
870 
871 		retval = dev->setkeycode(dev, scancode, ke->keycode);
872 	} else {
873 		retval = dev->setkeycode_new(dev, ke, &old_keycode);
874 	}
875 
876 	if (retval)
877 		goto out;
878 
879 	/* Make sure KEY_RESERVED did not get enabled. */
880 	__clear_bit(KEY_RESERVED, dev->keybit);
881 
882 	/*
883 	 * Simulate keyup event if keycode is not present
884 	 * in the keymap anymore
885 	 */
886 	if (test_bit(EV_KEY, dev->evbit) &&
887 	    !is_event_supported(old_keycode, dev->keybit, KEY_MAX) &&
888 	    __test_and_clear_bit(old_keycode, dev->key)) {
889 
890 		input_pass_event(dev, NULL, EV_KEY, old_keycode, 0);
891 		if (dev->sync)
892 			input_pass_event(dev, NULL, EV_SYN, SYN_REPORT, 1);
893 	}
894 
895  out:
896 	spin_unlock_irqrestore(&dev->event_lock, flags);
897 
898 	return retval;
899 }
900 EXPORT_SYMBOL(input_set_keycode);
901 
902 #define MATCH_BIT(bit, max) \
903 		for (i = 0; i < BITS_TO_LONGS(max); i++) \
904 			if ((id->bit[i] & dev->bit[i]) != id->bit[i]) \
905 				break; \
906 		if (i != BITS_TO_LONGS(max)) \
907 			continue;
908 
909 static const struct input_device_id *input_match_device(struct input_handler *handler,
910 							struct input_dev *dev)
911 {
912 	const struct input_device_id *id;
913 	int i;
914 
915 	for (id = handler->id_table; id->flags || id->driver_info; id++) {
916 
917 		if (id->flags & INPUT_DEVICE_ID_MATCH_BUS)
918 			if (id->bustype != dev->id.bustype)
919 				continue;
920 
921 		if (id->flags & INPUT_DEVICE_ID_MATCH_VENDOR)
922 			if (id->vendor != dev->id.vendor)
923 				continue;
924 
925 		if (id->flags & INPUT_DEVICE_ID_MATCH_PRODUCT)
926 			if (id->product != dev->id.product)
927 				continue;
928 
929 		if (id->flags & INPUT_DEVICE_ID_MATCH_VERSION)
930 			if (id->version != dev->id.version)
931 				continue;
932 
933 		MATCH_BIT(evbit,  EV_MAX);
934 		MATCH_BIT(keybit, KEY_MAX);
935 		MATCH_BIT(relbit, REL_MAX);
936 		MATCH_BIT(absbit, ABS_MAX);
937 		MATCH_BIT(mscbit, MSC_MAX);
938 		MATCH_BIT(ledbit, LED_MAX);
939 		MATCH_BIT(sndbit, SND_MAX);
940 		MATCH_BIT(ffbit,  FF_MAX);
941 		MATCH_BIT(swbit,  SW_MAX);
942 
943 		if (!handler->match || handler->match(handler, dev))
944 			return id;
945 	}
946 
947 	return NULL;
948 }
949 
950 static int input_attach_handler(struct input_dev *dev, struct input_handler *handler)
951 {
952 	const struct input_device_id *id;
953 	int error;
954 
955 	id = input_match_device(handler, dev);
956 	if (!id)
957 		return -ENODEV;
958 
959 	error = handler->connect(handler, dev, id);
960 	if (error && error != -ENODEV)
961 		printk(KERN_ERR
962 			"input: failed to attach handler %s to device %s, "
963 			"error: %d\n",
964 			handler->name, kobject_name(&dev->dev.kobj), error);
965 
966 	return error;
967 }
968 
969 #ifdef CONFIG_COMPAT
970 
971 static int input_bits_to_string(char *buf, int buf_size,
972 				unsigned long bits, bool skip_empty)
973 {
974 	int len = 0;
975 
976 	if (INPUT_COMPAT_TEST) {
977 		u32 dword = bits >> 32;
978 		if (dword || !skip_empty)
979 			len += snprintf(buf, buf_size, "%x ", dword);
980 
981 		dword = bits & 0xffffffffUL;
982 		if (dword || !skip_empty || len)
983 			len += snprintf(buf + len, max(buf_size - len, 0),
984 					"%x", dword);
985 	} else {
986 		if (bits || !skip_empty)
987 			len += snprintf(buf, buf_size, "%lx", bits);
988 	}
989 
990 	return len;
991 }
992 
993 #else /* !CONFIG_COMPAT */
994 
995 static int input_bits_to_string(char *buf, int buf_size,
996 				unsigned long bits, bool skip_empty)
997 {
998 	return bits || !skip_empty ?
999 		snprintf(buf, buf_size, "%lx", bits) : 0;
1000 }
1001 
1002 #endif
1003 
1004 #ifdef CONFIG_PROC_FS
1005 
1006 static struct proc_dir_entry *proc_bus_input_dir;
1007 static DECLARE_WAIT_QUEUE_HEAD(input_devices_poll_wait);
1008 static int input_devices_state;
1009 
1010 static inline void input_wakeup_procfs_readers(void)
1011 {
1012 	input_devices_state++;
1013 	wake_up(&input_devices_poll_wait);
1014 }
1015 
1016 static unsigned int input_proc_devices_poll(struct file *file, poll_table *wait)
1017 {
1018 	poll_wait(file, &input_devices_poll_wait, wait);
1019 	if (file->f_version != input_devices_state) {
1020 		file->f_version = input_devices_state;
1021 		return POLLIN | POLLRDNORM;
1022 	}
1023 
1024 	return 0;
1025 }
1026 
1027 union input_seq_state {
1028 	struct {
1029 		unsigned short pos;
1030 		bool mutex_acquired;
1031 	};
1032 	void *p;
1033 };
1034 
1035 static void *input_devices_seq_start(struct seq_file *seq, loff_t *pos)
1036 {
1037 	union input_seq_state *state = (union input_seq_state *)&seq->private;
1038 	int error;
1039 
1040 	/* We need to fit into seq->private pointer */
1041 	BUILD_BUG_ON(sizeof(union input_seq_state) != sizeof(seq->private));
1042 
1043 	error = mutex_lock_interruptible(&input_mutex);
1044 	if (error) {
1045 		state->mutex_acquired = false;
1046 		return ERR_PTR(error);
1047 	}
1048 
1049 	state->mutex_acquired = true;
1050 
1051 	return seq_list_start(&input_dev_list, *pos);
1052 }
1053 
1054 static void *input_devices_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1055 {
1056 	return seq_list_next(v, &input_dev_list, pos);
1057 }
1058 
1059 static void input_seq_stop(struct seq_file *seq, void *v)
1060 {
1061 	union input_seq_state *state = (union input_seq_state *)&seq->private;
1062 
1063 	if (state->mutex_acquired)
1064 		mutex_unlock(&input_mutex);
1065 }
1066 
1067 static void input_seq_print_bitmap(struct seq_file *seq, const char *name,
1068 				   unsigned long *bitmap, int max)
1069 {
1070 	int i;
1071 	bool skip_empty = true;
1072 	char buf[18];
1073 
1074 	seq_printf(seq, "B: %s=", name);
1075 
1076 	for (i = BITS_TO_LONGS(max) - 1; i >= 0; i--) {
1077 		if (input_bits_to_string(buf, sizeof(buf),
1078 					 bitmap[i], skip_empty)) {
1079 			skip_empty = false;
1080 			seq_printf(seq, "%s%s", buf, i > 0 ? " " : "");
1081 		}
1082 	}
1083 
1084 	/*
1085 	 * If no output was produced print a single 0.
1086 	 */
1087 	if (skip_empty)
1088 		seq_puts(seq, "0");
1089 
1090 	seq_putc(seq, '\n');
1091 }
1092 
1093 static int input_devices_seq_show(struct seq_file *seq, void *v)
1094 {
1095 	struct input_dev *dev = container_of(v, struct input_dev, node);
1096 	const char *path = kobject_get_path(&dev->dev.kobj, GFP_KERNEL);
1097 	struct input_handle *handle;
1098 
1099 	seq_printf(seq, "I: Bus=%04x Vendor=%04x Product=%04x Version=%04x\n",
1100 		   dev->id.bustype, dev->id.vendor, dev->id.product, dev->id.version);
1101 
1102 	seq_printf(seq, "N: Name=\"%s\"\n", dev->name ? dev->name : "");
1103 	seq_printf(seq, "P: Phys=%s\n", dev->phys ? dev->phys : "");
1104 	seq_printf(seq, "S: Sysfs=%s\n", path ? path : "");
1105 	seq_printf(seq, "U: Uniq=%s\n", dev->uniq ? dev->uniq : "");
1106 	seq_printf(seq, "H: Handlers=");
1107 
1108 	list_for_each_entry(handle, &dev->h_list, d_node)
1109 		seq_printf(seq, "%s ", handle->name);
1110 	seq_putc(seq, '\n');
1111 
1112 	input_seq_print_bitmap(seq, "EV", dev->evbit, EV_MAX);
1113 	if (test_bit(EV_KEY, dev->evbit))
1114 		input_seq_print_bitmap(seq, "KEY", dev->keybit, KEY_MAX);
1115 	if (test_bit(EV_REL, dev->evbit))
1116 		input_seq_print_bitmap(seq, "REL", dev->relbit, REL_MAX);
1117 	if (test_bit(EV_ABS, dev->evbit))
1118 		input_seq_print_bitmap(seq, "ABS", dev->absbit, ABS_MAX);
1119 	if (test_bit(EV_MSC, dev->evbit))
1120 		input_seq_print_bitmap(seq, "MSC", dev->mscbit, MSC_MAX);
1121 	if (test_bit(EV_LED, dev->evbit))
1122 		input_seq_print_bitmap(seq, "LED", dev->ledbit, LED_MAX);
1123 	if (test_bit(EV_SND, dev->evbit))
1124 		input_seq_print_bitmap(seq, "SND", dev->sndbit, SND_MAX);
1125 	if (test_bit(EV_FF, dev->evbit))
1126 		input_seq_print_bitmap(seq, "FF", dev->ffbit, FF_MAX);
1127 	if (test_bit(EV_SW, dev->evbit))
1128 		input_seq_print_bitmap(seq, "SW", dev->swbit, SW_MAX);
1129 
1130 	seq_putc(seq, '\n');
1131 
1132 	kfree(path);
1133 	return 0;
1134 }
1135 
1136 static const struct seq_operations input_devices_seq_ops = {
1137 	.start	= input_devices_seq_start,
1138 	.next	= input_devices_seq_next,
1139 	.stop	= input_seq_stop,
1140 	.show	= input_devices_seq_show,
1141 };
1142 
1143 static int input_proc_devices_open(struct inode *inode, struct file *file)
1144 {
1145 	return seq_open(file, &input_devices_seq_ops);
1146 }
1147 
1148 static const struct file_operations input_devices_fileops = {
1149 	.owner		= THIS_MODULE,
1150 	.open		= input_proc_devices_open,
1151 	.poll		= input_proc_devices_poll,
1152 	.read		= seq_read,
1153 	.llseek		= seq_lseek,
1154 	.release	= seq_release,
1155 };
1156 
1157 static void *input_handlers_seq_start(struct seq_file *seq, loff_t *pos)
1158 {
1159 	union input_seq_state *state = (union input_seq_state *)&seq->private;
1160 	int error;
1161 
1162 	/* We need to fit into seq->private pointer */
1163 	BUILD_BUG_ON(sizeof(union input_seq_state) != sizeof(seq->private));
1164 
1165 	error = mutex_lock_interruptible(&input_mutex);
1166 	if (error) {
1167 		state->mutex_acquired = false;
1168 		return ERR_PTR(error);
1169 	}
1170 
1171 	state->mutex_acquired = true;
1172 	state->pos = *pos;
1173 
1174 	return seq_list_start(&input_handler_list, *pos);
1175 }
1176 
1177 static void *input_handlers_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1178 {
1179 	union input_seq_state *state = (union input_seq_state *)&seq->private;
1180 
1181 	state->pos = *pos + 1;
1182 	return seq_list_next(v, &input_handler_list, pos);
1183 }
1184 
1185 static int input_handlers_seq_show(struct seq_file *seq, void *v)
1186 {
1187 	struct input_handler *handler = container_of(v, struct input_handler, node);
1188 	union input_seq_state *state = (union input_seq_state *)&seq->private;
1189 
1190 	seq_printf(seq, "N: Number=%u Name=%s", state->pos, handler->name);
1191 	if (handler->filter)
1192 		seq_puts(seq, " (filter)");
1193 	if (handler->fops)
1194 		seq_printf(seq, " Minor=%d", handler->minor);
1195 	seq_putc(seq, '\n');
1196 
1197 	return 0;
1198 }
1199 
1200 static const struct seq_operations input_handlers_seq_ops = {
1201 	.start	= input_handlers_seq_start,
1202 	.next	= input_handlers_seq_next,
1203 	.stop	= input_seq_stop,
1204 	.show	= input_handlers_seq_show,
1205 };
1206 
1207 static int input_proc_handlers_open(struct inode *inode, struct file *file)
1208 {
1209 	return seq_open(file, &input_handlers_seq_ops);
1210 }
1211 
1212 static const struct file_operations input_handlers_fileops = {
1213 	.owner		= THIS_MODULE,
1214 	.open		= input_proc_handlers_open,
1215 	.read		= seq_read,
1216 	.llseek		= seq_lseek,
1217 	.release	= seq_release,
1218 };
1219 
1220 static int __init input_proc_init(void)
1221 {
1222 	struct proc_dir_entry *entry;
1223 
1224 	proc_bus_input_dir = proc_mkdir("bus/input", NULL);
1225 	if (!proc_bus_input_dir)
1226 		return -ENOMEM;
1227 
1228 	entry = proc_create("devices", 0, proc_bus_input_dir,
1229 			    &input_devices_fileops);
1230 	if (!entry)
1231 		goto fail1;
1232 
1233 	entry = proc_create("handlers", 0, proc_bus_input_dir,
1234 			    &input_handlers_fileops);
1235 	if (!entry)
1236 		goto fail2;
1237 
1238 	return 0;
1239 
1240  fail2:	remove_proc_entry("devices", proc_bus_input_dir);
1241  fail1: remove_proc_entry("bus/input", NULL);
1242 	return -ENOMEM;
1243 }
1244 
1245 static void input_proc_exit(void)
1246 {
1247 	remove_proc_entry("devices", proc_bus_input_dir);
1248 	remove_proc_entry("handlers", proc_bus_input_dir);
1249 	remove_proc_entry("bus/input", NULL);
1250 }
1251 
1252 #else /* !CONFIG_PROC_FS */
1253 static inline void input_wakeup_procfs_readers(void) { }
1254 static inline int input_proc_init(void) { return 0; }
1255 static inline void input_proc_exit(void) { }
1256 #endif
1257 
1258 #define INPUT_DEV_STRING_ATTR_SHOW(name)				\
1259 static ssize_t input_dev_show_##name(struct device *dev,		\
1260 				     struct device_attribute *attr,	\
1261 				     char *buf)				\
1262 {									\
1263 	struct input_dev *input_dev = to_input_dev(dev);		\
1264 									\
1265 	return scnprintf(buf, PAGE_SIZE, "%s\n",			\
1266 			 input_dev->name ? input_dev->name : "");	\
1267 }									\
1268 static DEVICE_ATTR(name, S_IRUGO, input_dev_show_##name, NULL)
1269 
1270 INPUT_DEV_STRING_ATTR_SHOW(name);
1271 INPUT_DEV_STRING_ATTR_SHOW(phys);
1272 INPUT_DEV_STRING_ATTR_SHOW(uniq);
1273 
1274 static int input_print_modalias_bits(char *buf, int size,
1275 				     char name, unsigned long *bm,
1276 				     unsigned int min_bit, unsigned int max_bit)
1277 {
1278 	int len = 0, i;
1279 
1280 	len += snprintf(buf, max(size, 0), "%c", name);
1281 	for (i = min_bit; i < max_bit; i++)
1282 		if (bm[BIT_WORD(i)] & BIT_MASK(i))
1283 			len += snprintf(buf + len, max(size - len, 0), "%X,", i);
1284 	return len;
1285 }
1286 
1287 static int input_print_modalias(char *buf, int size, struct input_dev *id,
1288 				int add_cr)
1289 {
1290 	int len;
1291 
1292 	len = snprintf(buf, max(size, 0),
1293 		       "input:b%04Xv%04Xp%04Xe%04X-",
1294 		       id->id.bustype, id->id.vendor,
1295 		       id->id.product, id->id.version);
1296 
1297 	len += input_print_modalias_bits(buf + len, size - len,
1298 				'e', id->evbit, 0, EV_MAX);
1299 	len += input_print_modalias_bits(buf + len, size - len,
1300 				'k', id->keybit, KEY_MIN_INTERESTING, KEY_MAX);
1301 	len += input_print_modalias_bits(buf + len, size - len,
1302 				'r', id->relbit, 0, REL_MAX);
1303 	len += input_print_modalias_bits(buf + len, size - len,
1304 				'a', id->absbit, 0, ABS_MAX);
1305 	len += input_print_modalias_bits(buf + len, size - len,
1306 				'm', id->mscbit, 0, MSC_MAX);
1307 	len += input_print_modalias_bits(buf + len, size - len,
1308 				'l', id->ledbit, 0, LED_MAX);
1309 	len += input_print_modalias_bits(buf + len, size - len,
1310 				's', id->sndbit, 0, SND_MAX);
1311 	len += input_print_modalias_bits(buf + len, size - len,
1312 				'f', id->ffbit, 0, FF_MAX);
1313 	len += input_print_modalias_bits(buf + len, size - len,
1314 				'w', id->swbit, 0, SW_MAX);
1315 
1316 	if (add_cr)
1317 		len += snprintf(buf + len, max(size - len, 0), "\n");
1318 
1319 	return len;
1320 }
1321 
1322 static ssize_t input_dev_show_modalias(struct device *dev,
1323 				       struct device_attribute *attr,
1324 				       char *buf)
1325 {
1326 	struct input_dev *id = to_input_dev(dev);
1327 	ssize_t len;
1328 
1329 	len = input_print_modalias(buf, PAGE_SIZE, id, 1);
1330 
1331 	return min_t(int, len, PAGE_SIZE);
1332 }
1333 static DEVICE_ATTR(modalias, S_IRUGO, input_dev_show_modalias, NULL);
1334 
1335 static struct attribute *input_dev_attrs[] = {
1336 	&dev_attr_name.attr,
1337 	&dev_attr_phys.attr,
1338 	&dev_attr_uniq.attr,
1339 	&dev_attr_modalias.attr,
1340 	NULL
1341 };
1342 
1343 static struct attribute_group input_dev_attr_group = {
1344 	.attrs	= input_dev_attrs,
1345 };
1346 
1347 #define INPUT_DEV_ID_ATTR(name)						\
1348 static ssize_t input_dev_show_id_##name(struct device *dev,		\
1349 					struct device_attribute *attr,	\
1350 					char *buf)			\
1351 {									\
1352 	struct input_dev *input_dev = to_input_dev(dev);		\
1353 	return scnprintf(buf, PAGE_SIZE, "%04x\n", input_dev->id.name);	\
1354 }									\
1355 static DEVICE_ATTR(name, S_IRUGO, input_dev_show_id_##name, NULL)
1356 
1357 INPUT_DEV_ID_ATTR(bustype);
1358 INPUT_DEV_ID_ATTR(vendor);
1359 INPUT_DEV_ID_ATTR(product);
1360 INPUT_DEV_ID_ATTR(version);
1361 
1362 static struct attribute *input_dev_id_attrs[] = {
1363 	&dev_attr_bustype.attr,
1364 	&dev_attr_vendor.attr,
1365 	&dev_attr_product.attr,
1366 	&dev_attr_version.attr,
1367 	NULL
1368 };
1369 
1370 static struct attribute_group input_dev_id_attr_group = {
1371 	.name	= "id",
1372 	.attrs	= input_dev_id_attrs,
1373 };
1374 
1375 static int input_print_bitmap(char *buf, int buf_size, unsigned long *bitmap,
1376 			      int max, int add_cr)
1377 {
1378 	int i;
1379 	int len = 0;
1380 	bool skip_empty = true;
1381 
1382 	for (i = BITS_TO_LONGS(max) - 1; i >= 0; i--) {
1383 		len += input_bits_to_string(buf + len, max(buf_size - len, 0),
1384 					    bitmap[i], skip_empty);
1385 		if (len) {
1386 			skip_empty = false;
1387 			if (i > 0)
1388 				len += snprintf(buf + len, max(buf_size - len, 0), " ");
1389 		}
1390 	}
1391 
1392 	/*
1393 	 * If no output was produced print a single 0.
1394 	 */
1395 	if (len == 0)
1396 		len = snprintf(buf, buf_size, "%d", 0);
1397 
1398 	if (add_cr)
1399 		len += snprintf(buf + len, max(buf_size - len, 0), "\n");
1400 
1401 	return len;
1402 }
1403 
1404 #define INPUT_DEV_CAP_ATTR(ev, bm)					\
1405 static ssize_t input_dev_show_cap_##bm(struct device *dev,		\
1406 				       struct device_attribute *attr,	\
1407 				       char *buf)			\
1408 {									\
1409 	struct input_dev *input_dev = to_input_dev(dev);		\
1410 	int len = input_print_bitmap(buf, PAGE_SIZE,			\
1411 				     input_dev->bm##bit, ev##_MAX,	\
1412 				     true);				\
1413 	return min_t(int, len, PAGE_SIZE);				\
1414 }									\
1415 static DEVICE_ATTR(bm, S_IRUGO, input_dev_show_cap_##bm, NULL)
1416 
1417 INPUT_DEV_CAP_ATTR(EV, ev);
1418 INPUT_DEV_CAP_ATTR(KEY, key);
1419 INPUT_DEV_CAP_ATTR(REL, rel);
1420 INPUT_DEV_CAP_ATTR(ABS, abs);
1421 INPUT_DEV_CAP_ATTR(MSC, msc);
1422 INPUT_DEV_CAP_ATTR(LED, led);
1423 INPUT_DEV_CAP_ATTR(SND, snd);
1424 INPUT_DEV_CAP_ATTR(FF, ff);
1425 INPUT_DEV_CAP_ATTR(SW, sw);
1426 
1427 static struct attribute *input_dev_caps_attrs[] = {
1428 	&dev_attr_ev.attr,
1429 	&dev_attr_key.attr,
1430 	&dev_attr_rel.attr,
1431 	&dev_attr_abs.attr,
1432 	&dev_attr_msc.attr,
1433 	&dev_attr_led.attr,
1434 	&dev_attr_snd.attr,
1435 	&dev_attr_ff.attr,
1436 	&dev_attr_sw.attr,
1437 	NULL
1438 };
1439 
1440 static struct attribute_group input_dev_caps_attr_group = {
1441 	.name	= "capabilities",
1442 	.attrs	= input_dev_caps_attrs,
1443 };
1444 
1445 static const struct attribute_group *input_dev_attr_groups[] = {
1446 	&input_dev_attr_group,
1447 	&input_dev_id_attr_group,
1448 	&input_dev_caps_attr_group,
1449 	NULL
1450 };
1451 
1452 static void input_dev_release(struct device *device)
1453 {
1454 	struct input_dev *dev = to_input_dev(device);
1455 
1456 	input_ff_destroy(dev);
1457 	input_mt_destroy_slots(dev);
1458 	kfree(dev->absinfo);
1459 	kfree(dev);
1460 
1461 	module_put(THIS_MODULE);
1462 }
1463 
1464 /*
1465  * Input uevent interface - loading event handlers based on
1466  * device bitfields.
1467  */
1468 static int input_add_uevent_bm_var(struct kobj_uevent_env *env,
1469 				   const char *name, unsigned long *bitmap, int max)
1470 {
1471 	int len;
1472 
1473 	if (add_uevent_var(env, "%s=", name))
1474 		return -ENOMEM;
1475 
1476 	len = input_print_bitmap(&env->buf[env->buflen - 1],
1477 				 sizeof(env->buf) - env->buflen,
1478 				 bitmap, max, false);
1479 	if (len >= (sizeof(env->buf) - env->buflen))
1480 		return -ENOMEM;
1481 
1482 	env->buflen += len;
1483 	return 0;
1484 }
1485 
1486 static int input_add_uevent_modalias_var(struct kobj_uevent_env *env,
1487 					 struct input_dev *dev)
1488 {
1489 	int len;
1490 
1491 	if (add_uevent_var(env, "MODALIAS="))
1492 		return -ENOMEM;
1493 
1494 	len = input_print_modalias(&env->buf[env->buflen - 1],
1495 				   sizeof(env->buf) - env->buflen,
1496 				   dev, 0);
1497 	if (len >= (sizeof(env->buf) - env->buflen))
1498 		return -ENOMEM;
1499 
1500 	env->buflen += len;
1501 	return 0;
1502 }
1503 
1504 #define INPUT_ADD_HOTPLUG_VAR(fmt, val...)				\
1505 	do {								\
1506 		int err = add_uevent_var(env, fmt, val);		\
1507 		if (err)						\
1508 			return err;					\
1509 	} while (0)
1510 
1511 #define INPUT_ADD_HOTPLUG_BM_VAR(name, bm, max)				\
1512 	do {								\
1513 		int err = input_add_uevent_bm_var(env, name, bm, max);	\
1514 		if (err)						\
1515 			return err;					\
1516 	} while (0)
1517 
1518 #define INPUT_ADD_HOTPLUG_MODALIAS_VAR(dev)				\
1519 	do {								\
1520 		int err = input_add_uevent_modalias_var(env, dev);	\
1521 		if (err)						\
1522 			return err;					\
1523 	} while (0)
1524 
1525 static int input_dev_uevent(struct device *device, struct kobj_uevent_env *env)
1526 {
1527 	struct input_dev *dev = to_input_dev(device);
1528 
1529 	INPUT_ADD_HOTPLUG_VAR("PRODUCT=%x/%x/%x/%x",
1530 				dev->id.bustype, dev->id.vendor,
1531 				dev->id.product, dev->id.version);
1532 	if (dev->name)
1533 		INPUT_ADD_HOTPLUG_VAR("NAME=\"%s\"", dev->name);
1534 	if (dev->phys)
1535 		INPUT_ADD_HOTPLUG_VAR("PHYS=\"%s\"", dev->phys);
1536 	if (dev->uniq)
1537 		INPUT_ADD_HOTPLUG_VAR("UNIQ=\"%s\"", dev->uniq);
1538 
1539 	INPUT_ADD_HOTPLUG_BM_VAR("EV=", dev->evbit, EV_MAX);
1540 	if (test_bit(EV_KEY, dev->evbit))
1541 		INPUT_ADD_HOTPLUG_BM_VAR("KEY=", dev->keybit, KEY_MAX);
1542 	if (test_bit(EV_REL, dev->evbit))
1543 		INPUT_ADD_HOTPLUG_BM_VAR("REL=", dev->relbit, REL_MAX);
1544 	if (test_bit(EV_ABS, dev->evbit))
1545 		INPUT_ADD_HOTPLUG_BM_VAR("ABS=", dev->absbit, ABS_MAX);
1546 	if (test_bit(EV_MSC, dev->evbit))
1547 		INPUT_ADD_HOTPLUG_BM_VAR("MSC=", dev->mscbit, MSC_MAX);
1548 	if (test_bit(EV_LED, dev->evbit))
1549 		INPUT_ADD_HOTPLUG_BM_VAR("LED=", dev->ledbit, LED_MAX);
1550 	if (test_bit(EV_SND, dev->evbit))
1551 		INPUT_ADD_HOTPLUG_BM_VAR("SND=", dev->sndbit, SND_MAX);
1552 	if (test_bit(EV_FF, dev->evbit))
1553 		INPUT_ADD_HOTPLUG_BM_VAR("FF=", dev->ffbit, FF_MAX);
1554 	if (test_bit(EV_SW, dev->evbit))
1555 		INPUT_ADD_HOTPLUG_BM_VAR("SW=", dev->swbit, SW_MAX);
1556 
1557 	INPUT_ADD_HOTPLUG_MODALIAS_VAR(dev);
1558 
1559 	return 0;
1560 }
1561 
1562 #define INPUT_DO_TOGGLE(dev, type, bits, on)				\
1563 	do {								\
1564 		int i;							\
1565 		bool active;						\
1566 									\
1567 		if (!test_bit(EV_##type, dev->evbit))			\
1568 			break;						\
1569 									\
1570 		for (i = 0; i < type##_MAX; i++) {			\
1571 			if (!test_bit(i, dev->bits##bit))		\
1572 				continue;				\
1573 									\
1574 			active = test_bit(i, dev->bits);		\
1575 			if (!active && !on)				\
1576 				continue;				\
1577 									\
1578 			dev->event(dev, EV_##type, i, on ? active : 0);	\
1579 		}							\
1580 	} while (0)
1581 
1582 static void input_dev_toggle(struct input_dev *dev, bool activate)
1583 {
1584 	if (!dev->event)
1585 		return;
1586 
1587 	INPUT_DO_TOGGLE(dev, LED, led, activate);
1588 	INPUT_DO_TOGGLE(dev, SND, snd, activate);
1589 
1590 	if (activate && test_bit(EV_REP, dev->evbit)) {
1591 		dev->event(dev, EV_REP, REP_PERIOD, dev->rep[REP_PERIOD]);
1592 		dev->event(dev, EV_REP, REP_DELAY, dev->rep[REP_DELAY]);
1593 	}
1594 }
1595 
1596 /**
1597  * input_reset_device() - reset/restore the state of input device
1598  * @dev: input device whose state needs to be reset
1599  *
1600  * This function tries to reset the state of an opened input device and
1601  * bring internal state and state if the hardware in sync with each other.
1602  * We mark all keys as released, restore LED state, repeat rate, etc.
1603  */
1604 void input_reset_device(struct input_dev *dev)
1605 {
1606 	mutex_lock(&dev->mutex);
1607 
1608 	if (dev->users) {
1609 		input_dev_toggle(dev, true);
1610 
1611 		/*
1612 		 * Keys that have been pressed at suspend time are unlikely
1613 		 * to be still pressed when we resume.
1614 		 */
1615 		spin_lock_irq(&dev->event_lock);
1616 		input_dev_release_keys(dev);
1617 		spin_unlock_irq(&dev->event_lock);
1618 	}
1619 
1620 	mutex_unlock(&dev->mutex);
1621 }
1622 EXPORT_SYMBOL(input_reset_device);
1623 
1624 #ifdef CONFIG_PM
1625 static int input_dev_suspend(struct device *dev)
1626 {
1627 	struct input_dev *input_dev = to_input_dev(dev);
1628 
1629 	mutex_lock(&input_dev->mutex);
1630 
1631 	if (input_dev->users)
1632 		input_dev_toggle(input_dev, false);
1633 
1634 	mutex_unlock(&input_dev->mutex);
1635 
1636 	return 0;
1637 }
1638 
1639 static int input_dev_resume(struct device *dev)
1640 {
1641 	struct input_dev *input_dev = to_input_dev(dev);
1642 
1643 	input_reset_device(input_dev);
1644 
1645 	return 0;
1646 }
1647 
1648 static const struct dev_pm_ops input_dev_pm_ops = {
1649 	.suspend	= input_dev_suspend,
1650 	.resume		= input_dev_resume,
1651 	.poweroff	= input_dev_suspend,
1652 	.restore	= input_dev_resume,
1653 };
1654 #endif /* CONFIG_PM */
1655 
1656 static struct device_type input_dev_type = {
1657 	.groups		= input_dev_attr_groups,
1658 	.release	= input_dev_release,
1659 	.uevent		= input_dev_uevent,
1660 #ifdef CONFIG_PM
1661 	.pm		= &input_dev_pm_ops,
1662 #endif
1663 };
1664 
1665 static char *input_devnode(struct device *dev, mode_t *mode)
1666 {
1667 	return kasprintf(GFP_KERNEL, "input/%s", dev_name(dev));
1668 }
1669 
1670 struct class input_class = {
1671 	.name		= "input",
1672 	.devnode	= input_devnode,
1673 };
1674 EXPORT_SYMBOL_GPL(input_class);
1675 
1676 /**
1677  * input_allocate_device - allocate memory for new input device
1678  *
1679  * Returns prepared struct input_dev or NULL.
1680  *
1681  * NOTE: Use input_free_device() to free devices that have not been
1682  * registered; input_unregister_device() should be used for already
1683  * registered devices.
1684  */
1685 struct input_dev *input_allocate_device(void)
1686 {
1687 	struct input_dev *dev;
1688 
1689 	dev = kzalloc(sizeof(struct input_dev), GFP_KERNEL);
1690 	if (dev) {
1691 		dev->dev.type = &input_dev_type;
1692 		dev->dev.class = &input_class;
1693 		device_initialize(&dev->dev);
1694 		mutex_init(&dev->mutex);
1695 		spin_lock_init(&dev->event_lock);
1696 		INIT_LIST_HEAD(&dev->h_list);
1697 		INIT_LIST_HEAD(&dev->node);
1698 
1699 		__module_get(THIS_MODULE);
1700 	}
1701 
1702 	return dev;
1703 }
1704 EXPORT_SYMBOL(input_allocate_device);
1705 
1706 /**
1707  * input_free_device - free memory occupied by input_dev structure
1708  * @dev: input device to free
1709  *
1710  * This function should only be used if input_register_device()
1711  * was not called yet or if it failed. Once device was registered
1712  * use input_unregister_device() and memory will be freed once last
1713  * reference to the device is dropped.
1714  *
1715  * Device should be allocated by input_allocate_device().
1716  *
1717  * NOTE: If there are references to the input device then memory
1718  * will not be freed until last reference is dropped.
1719  */
1720 void input_free_device(struct input_dev *dev)
1721 {
1722 	if (dev)
1723 		input_put_device(dev);
1724 }
1725 EXPORT_SYMBOL(input_free_device);
1726 
1727 /**
1728  * input_mt_create_slots() - create MT input slots
1729  * @dev: input device supporting MT events and finger tracking
1730  * @num_slots: number of slots used by the device
1731  *
1732  * This function allocates all necessary memory for MT slot handling in the
1733  * input device, and adds ABS_MT_SLOT to the device capabilities. All slots
1734  * are initially marked as unused by setting ABS_MT_TRACKING_ID to -1.
1735  */
1736 int input_mt_create_slots(struct input_dev *dev, unsigned int num_slots)
1737 {
1738 	int i;
1739 
1740 	if (!num_slots)
1741 		return 0;
1742 
1743 	dev->mt = kcalloc(num_slots, sizeof(struct input_mt_slot), GFP_KERNEL);
1744 	if (!dev->mt)
1745 		return -ENOMEM;
1746 
1747 	dev->mtsize = num_slots;
1748 	input_set_abs_params(dev, ABS_MT_SLOT, 0, num_slots - 1, 0, 0);
1749 
1750 	/* Mark slots as 'unused' */
1751 	for (i = 0; i < num_slots; i++)
1752 		dev->mt[i].abs[ABS_MT_TRACKING_ID - ABS_MT_FIRST] = -1;
1753 
1754 	return 0;
1755 }
1756 EXPORT_SYMBOL(input_mt_create_slots);
1757 
1758 /**
1759  * input_mt_destroy_slots() - frees the MT slots of the input device
1760  * @dev: input device with allocated MT slots
1761  *
1762  * This function is only needed in error path as the input core will
1763  * automatically free the MT slots when the device is destroyed.
1764  */
1765 void input_mt_destroy_slots(struct input_dev *dev)
1766 {
1767 	kfree(dev->mt);
1768 	dev->mt = NULL;
1769 	dev->mtsize = 0;
1770 }
1771 EXPORT_SYMBOL(input_mt_destroy_slots);
1772 
1773 /**
1774  * input_set_capability - mark device as capable of a certain event
1775  * @dev: device that is capable of emitting or accepting event
1776  * @type: type of the event (EV_KEY, EV_REL, etc...)
1777  * @code: event code
1778  *
1779  * In addition to setting up corresponding bit in appropriate capability
1780  * bitmap the function also adjusts dev->evbit.
1781  */
1782 void input_set_capability(struct input_dev *dev, unsigned int type, unsigned int code)
1783 {
1784 	switch (type) {
1785 	case EV_KEY:
1786 		__set_bit(code, dev->keybit);
1787 		break;
1788 
1789 	case EV_REL:
1790 		__set_bit(code, dev->relbit);
1791 		break;
1792 
1793 	case EV_ABS:
1794 		__set_bit(code, dev->absbit);
1795 		break;
1796 
1797 	case EV_MSC:
1798 		__set_bit(code, dev->mscbit);
1799 		break;
1800 
1801 	case EV_SW:
1802 		__set_bit(code, dev->swbit);
1803 		break;
1804 
1805 	case EV_LED:
1806 		__set_bit(code, dev->ledbit);
1807 		break;
1808 
1809 	case EV_SND:
1810 		__set_bit(code, dev->sndbit);
1811 		break;
1812 
1813 	case EV_FF:
1814 		__set_bit(code, dev->ffbit);
1815 		break;
1816 
1817 	case EV_PWR:
1818 		/* do nothing */
1819 		break;
1820 
1821 	default:
1822 		printk(KERN_ERR
1823 			"input_set_capability: unknown type %u (code %u)\n",
1824 			type, code);
1825 		dump_stack();
1826 		return;
1827 	}
1828 
1829 	__set_bit(type, dev->evbit);
1830 }
1831 EXPORT_SYMBOL(input_set_capability);
1832 
1833 #define INPUT_CLEANSE_BITMASK(dev, type, bits)				\
1834 	do {								\
1835 		if (!test_bit(EV_##type, dev->evbit))			\
1836 			memset(dev->bits##bit, 0,			\
1837 				sizeof(dev->bits##bit));		\
1838 	} while (0)
1839 
1840 static void input_cleanse_bitmasks(struct input_dev *dev)
1841 {
1842 	INPUT_CLEANSE_BITMASK(dev, KEY, key);
1843 	INPUT_CLEANSE_BITMASK(dev, REL, rel);
1844 	INPUT_CLEANSE_BITMASK(dev, ABS, abs);
1845 	INPUT_CLEANSE_BITMASK(dev, MSC, msc);
1846 	INPUT_CLEANSE_BITMASK(dev, LED, led);
1847 	INPUT_CLEANSE_BITMASK(dev, SND, snd);
1848 	INPUT_CLEANSE_BITMASK(dev, FF, ff);
1849 	INPUT_CLEANSE_BITMASK(dev, SW, sw);
1850 }
1851 
1852 /**
1853  * input_register_device - register device with input core
1854  * @dev: device to be registered
1855  *
1856  * This function registers device with input core. The device must be
1857  * allocated with input_allocate_device() and all it's capabilities
1858  * set up before registering.
1859  * If function fails the device must be freed with input_free_device().
1860  * Once device has been successfully registered it can be unregistered
1861  * with input_unregister_device(); input_free_device() should not be
1862  * called in this case.
1863  */
1864 int input_register_device(struct input_dev *dev)
1865 {
1866 	static atomic_t input_no = ATOMIC_INIT(0);
1867 	struct input_handler *handler;
1868 	const char *path;
1869 	int error;
1870 
1871 	/* Every input device generates EV_SYN/SYN_REPORT events. */
1872 	__set_bit(EV_SYN, dev->evbit);
1873 
1874 	/* KEY_RESERVED is not supposed to be transmitted to userspace. */
1875 	__clear_bit(KEY_RESERVED, dev->keybit);
1876 
1877 	/* Make sure that bitmasks not mentioned in dev->evbit are clean. */
1878 	input_cleanse_bitmasks(dev);
1879 
1880 	/*
1881 	 * If delay and period are pre-set by the driver, then autorepeating
1882 	 * is handled by the driver itself and we don't do it in input.c.
1883 	 */
1884 	init_timer(&dev->timer);
1885 	if (!dev->rep[REP_DELAY] && !dev->rep[REP_PERIOD]) {
1886 		dev->timer.data = (long) dev;
1887 		dev->timer.function = input_repeat_key;
1888 		dev->rep[REP_DELAY] = 250;
1889 		dev->rep[REP_PERIOD] = 33;
1890 	}
1891 
1892 	if (!dev->getkeycode && !dev->getkeycode_new)
1893 		dev->getkeycode_new = input_default_getkeycode;
1894 
1895 	if (!dev->setkeycode && !dev->setkeycode_new)
1896 		dev->setkeycode_new = input_default_setkeycode;
1897 
1898 	dev_set_name(&dev->dev, "input%ld",
1899 		     (unsigned long) atomic_inc_return(&input_no) - 1);
1900 
1901 	error = device_add(&dev->dev);
1902 	if (error)
1903 		return error;
1904 
1905 	path = kobject_get_path(&dev->dev.kobj, GFP_KERNEL);
1906 	printk(KERN_INFO "input: %s as %s\n",
1907 		dev->name ? dev->name : "Unspecified device", path ? path : "N/A");
1908 	kfree(path);
1909 
1910 	error = mutex_lock_interruptible(&input_mutex);
1911 	if (error) {
1912 		device_del(&dev->dev);
1913 		return error;
1914 	}
1915 
1916 	list_add_tail(&dev->node, &input_dev_list);
1917 
1918 	list_for_each_entry(handler, &input_handler_list, node)
1919 		input_attach_handler(dev, handler);
1920 
1921 	input_wakeup_procfs_readers();
1922 
1923 	mutex_unlock(&input_mutex);
1924 
1925 	return 0;
1926 }
1927 EXPORT_SYMBOL(input_register_device);
1928 
1929 /**
1930  * input_unregister_device - unregister previously registered device
1931  * @dev: device to be unregistered
1932  *
1933  * This function unregisters an input device. Once device is unregistered
1934  * the caller should not try to access it as it may get freed at any moment.
1935  */
1936 void input_unregister_device(struct input_dev *dev)
1937 {
1938 	struct input_handle *handle, *next;
1939 
1940 	input_disconnect_device(dev);
1941 
1942 	mutex_lock(&input_mutex);
1943 
1944 	list_for_each_entry_safe(handle, next, &dev->h_list, d_node)
1945 		handle->handler->disconnect(handle);
1946 	WARN_ON(!list_empty(&dev->h_list));
1947 
1948 	del_timer_sync(&dev->timer);
1949 	list_del_init(&dev->node);
1950 
1951 	input_wakeup_procfs_readers();
1952 
1953 	mutex_unlock(&input_mutex);
1954 
1955 	device_unregister(&dev->dev);
1956 }
1957 EXPORT_SYMBOL(input_unregister_device);
1958 
1959 /**
1960  * input_register_handler - register a new input handler
1961  * @handler: handler to be registered
1962  *
1963  * This function registers a new input handler (interface) for input
1964  * devices in the system and attaches it to all input devices that
1965  * are compatible with the handler.
1966  */
1967 int input_register_handler(struct input_handler *handler)
1968 {
1969 	struct input_dev *dev;
1970 	int retval;
1971 
1972 	retval = mutex_lock_interruptible(&input_mutex);
1973 	if (retval)
1974 		return retval;
1975 
1976 	INIT_LIST_HEAD(&handler->h_list);
1977 
1978 	if (handler->fops != NULL) {
1979 		if (input_table[handler->minor >> 5]) {
1980 			retval = -EBUSY;
1981 			goto out;
1982 		}
1983 		input_table[handler->minor >> 5] = handler;
1984 	}
1985 
1986 	list_add_tail(&handler->node, &input_handler_list);
1987 
1988 	list_for_each_entry(dev, &input_dev_list, node)
1989 		input_attach_handler(dev, handler);
1990 
1991 	input_wakeup_procfs_readers();
1992 
1993  out:
1994 	mutex_unlock(&input_mutex);
1995 	return retval;
1996 }
1997 EXPORT_SYMBOL(input_register_handler);
1998 
1999 /**
2000  * input_unregister_handler - unregisters an input handler
2001  * @handler: handler to be unregistered
2002  *
2003  * This function disconnects a handler from its input devices and
2004  * removes it from lists of known handlers.
2005  */
2006 void input_unregister_handler(struct input_handler *handler)
2007 {
2008 	struct input_handle *handle, *next;
2009 
2010 	mutex_lock(&input_mutex);
2011 
2012 	list_for_each_entry_safe(handle, next, &handler->h_list, h_node)
2013 		handler->disconnect(handle);
2014 	WARN_ON(!list_empty(&handler->h_list));
2015 
2016 	list_del_init(&handler->node);
2017 
2018 	if (handler->fops != NULL)
2019 		input_table[handler->minor >> 5] = NULL;
2020 
2021 	input_wakeup_procfs_readers();
2022 
2023 	mutex_unlock(&input_mutex);
2024 }
2025 EXPORT_SYMBOL(input_unregister_handler);
2026 
2027 /**
2028  * input_handler_for_each_handle - handle iterator
2029  * @handler: input handler to iterate
2030  * @data: data for the callback
2031  * @fn: function to be called for each handle
2032  *
2033  * Iterate over @bus's list of devices, and call @fn for each, passing
2034  * it @data and stop when @fn returns a non-zero value. The function is
2035  * using RCU to traverse the list and therefore may be usind in atonic
2036  * contexts. The @fn callback is invoked from RCU critical section and
2037  * thus must not sleep.
2038  */
2039 int input_handler_for_each_handle(struct input_handler *handler, void *data,
2040 				  int (*fn)(struct input_handle *, void *))
2041 {
2042 	struct input_handle *handle;
2043 	int retval = 0;
2044 
2045 	rcu_read_lock();
2046 
2047 	list_for_each_entry_rcu(handle, &handler->h_list, h_node) {
2048 		retval = fn(handle, data);
2049 		if (retval)
2050 			break;
2051 	}
2052 
2053 	rcu_read_unlock();
2054 
2055 	return retval;
2056 }
2057 EXPORT_SYMBOL(input_handler_for_each_handle);
2058 
2059 /**
2060  * input_register_handle - register a new input handle
2061  * @handle: handle to register
2062  *
2063  * This function puts a new input handle onto device's
2064  * and handler's lists so that events can flow through
2065  * it once it is opened using input_open_device().
2066  *
2067  * This function is supposed to be called from handler's
2068  * connect() method.
2069  */
2070 int input_register_handle(struct input_handle *handle)
2071 {
2072 	struct input_handler *handler = handle->handler;
2073 	struct input_dev *dev = handle->dev;
2074 	int error;
2075 
2076 	/*
2077 	 * We take dev->mutex here to prevent race with
2078 	 * input_release_device().
2079 	 */
2080 	error = mutex_lock_interruptible(&dev->mutex);
2081 	if (error)
2082 		return error;
2083 
2084 	/*
2085 	 * Filters go to the head of the list, normal handlers
2086 	 * to the tail.
2087 	 */
2088 	if (handler->filter)
2089 		list_add_rcu(&handle->d_node, &dev->h_list);
2090 	else
2091 		list_add_tail_rcu(&handle->d_node, &dev->h_list);
2092 
2093 	mutex_unlock(&dev->mutex);
2094 
2095 	/*
2096 	 * Since we are supposed to be called from ->connect()
2097 	 * which is mutually exclusive with ->disconnect()
2098 	 * we can't be racing with input_unregister_handle()
2099 	 * and so separate lock is not needed here.
2100 	 */
2101 	list_add_tail_rcu(&handle->h_node, &handler->h_list);
2102 
2103 	if (handler->start)
2104 		handler->start(handle);
2105 
2106 	return 0;
2107 }
2108 EXPORT_SYMBOL(input_register_handle);
2109 
2110 /**
2111  * input_unregister_handle - unregister an input handle
2112  * @handle: handle to unregister
2113  *
2114  * This function removes input handle from device's
2115  * and handler's lists.
2116  *
2117  * This function is supposed to be called from handler's
2118  * disconnect() method.
2119  */
2120 void input_unregister_handle(struct input_handle *handle)
2121 {
2122 	struct input_dev *dev = handle->dev;
2123 
2124 	list_del_rcu(&handle->h_node);
2125 
2126 	/*
2127 	 * Take dev->mutex to prevent race with input_release_device().
2128 	 */
2129 	mutex_lock(&dev->mutex);
2130 	list_del_rcu(&handle->d_node);
2131 	mutex_unlock(&dev->mutex);
2132 
2133 	synchronize_rcu();
2134 }
2135 EXPORT_SYMBOL(input_unregister_handle);
2136 
2137 static int input_open_file(struct inode *inode, struct file *file)
2138 {
2139 	struct input_handler *handler;
2140 	const struct file_operations *old_fops, *new_fops = NULL;
2141 	int err;
2142 
2143 	err = mutex_lock_interruptible(&input_mutex);
2144 	if (err)
2145 		return err;
2146 
2147 	/* No load-on-demand here? */
2148 	handler = input_table[iminor(inode) >> 5];
2149 	if (handler)
2150 		new_fops = fops_get(handler->fops);
2151 
2152 	mutex_unlock(&input_mutex);
2153 
2154 	/*
2155 	 * That's _really_ odd. Usually NULL ->open means "nothing special",
2156 	 * not "no device". Oh, well...
2157 	 */
2158 	if (!new_fops || !new_fops->open) {
2159 		fops_put(new_fops);
2160 		err = -ENODEV;
2161 		goto out;
2162 	}
2163 
2164 	old_fops = file->f_op;
2165 	file->f_op = new_fops;
2166 
2167 	err = new_fops->open(inode, file);
2168 	if (err) {
2169 		fops_put(file->f_op);
2170 		file->f_op = fops_get(old_fops);
2171 	}
2172 	fops_put(old_fops);
2173 out:
2174 	return err;
2175 }
2176 
2177 static const struct file_operations input_fops = {
2178 	.owner = THIS_MODULE,
2179 	.open = input_open_file,
2180 	.llseek = noop_llseek,
2181 };
2182 
2183 static int __init input_init(void)
2184 {
2185 	int err;
2186 
2187 	err = class_register(&input_class);
2188 	if (err) {
2189 		printk(KERN_ERR "input: unable to register input_dev class\n");
2190 		return err;
2191 	}
2192 
2193 	err = input_proc_init();
2194 	if (err)
2195 		goto fail1;
2196 
2197 	err = register_chrdev(INPUT_MAJOR, "input", &input_fops);
2198 	if (err) {
2199 		printk(KERN_ERR "input: unable to register char major %d", INPUT_MAJOR);
2200 		goto fail2;
2201 	}
2202 
2203 	return 0;
2204 
2205  fail2:	input_proc_exit();
2206  fail1:	class_unregister(&input_class);
2207 	return err;
2208 }
2209 
2210 static void __exit input_exit(void)
2211 {
2212 	input_proc_exit();
2213 	unregister_chrdev(INPUT_MAJOR, "input");
2214 	class_unregister(&input_class);
2215 }
2216 
2217 subsys_initcall(input_init);
2218 module_exit(input_exit);
2219