1 /*
2  * Generic gameport layer
3  *
4  * Copyright (c) 1999-2002 Vojtech Pavlik
5  * Copyright (c) 2005 Dmitry Torokhov
6  */
7 
8 /*
9  * This program is free software; you can redistribute it and/or modify it
10  * under the terms of the GNU General Public License version 2 as published by
11  * the Free Software Foundation.
12  */
13 
14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15 
16 #include <linux/stddef.h>
17 #include <linux/module.h>
18 #include <linux/ioport.h>
19 #include <linux/init.h>
20 #include <linux/gameport.h>
21 #include <linux/slab.h>
22 #include <linux/delay.h>
23 #include <linux/workqueue.h>
24 #include <linux/sched.h>	/* HZ */
25 #include <linux/mutex.h>
26 #include <linux/timekeeping.h>
27 
28 /*#include <asm/io.h>*/
29 
30 MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
31 MODULE_DESCRIPTION("Generic gameport layer");
32 MODULE_LICENSE("GPL");
33 
34 static bool use_ktime = true;
35 module_param(use_ktime, bool, 0400);
36 MODULE_PARM_DESC(use_ktime, "Use ktime for measuring I/O speed");
37 
38 /*
39  * gameport_mutex protects entire gameport subsystem and is taken
40  * every time gameport port or driver registrered or unregistered.
41  */
42 static DEFINE_MUTEX(gameport_mutex);
43 
44 static LIST_HEAD(gameport_list);
45 
46 static struct bus_type gameport_bus;
47 
48 static void gameport_add_port(struct gameport *gameport);
49 static void gameport_attach_driver(struct gameport_driver *drv);
50 static void gameport_reconnect_port(struct gameport *gameport);
51 static void gameport_disconnect_port(struct gameport *gameport);
52 
53 #if defined(__i386__)
54 
55 #include <linux/i8253.h>
56 
57 #define DELTA(x,y)      ((y)-(x)+((y)<(x)?1193182/HZ:0))
58 #define GET_TIME(x)     do { x = get_time_pit(); } while (0)
59 
60 static unsigned int get_time_pit(void)
61 {
62 	unsigned long flags;
63 	unsigned int count;
64 
65 	raw_spin_lock_irqsave(&i8253_lock, flags);
66 	outb_p(0x00, 0x43);
67 	count = inb_p(0x40);
68 	count |= inb_p(0x40) << 8;
69 	raw_spin_unlock_irqrestore(&i8253_lock, flags);
70 
71 	return count;
72 }
73 
74 #endif
75 
76 
77 
78 /*
79  * gameport_measure_speed() measures the gameport i/o speed.
80  */
81 
82 static int gameport_measure_speed(struct gameport *gameport)
83 {
84 	unsigned int i, t, tx;
85 	u64 t1, t2, t3;
86 	unsigned long flags;
87 
88 	if (gameport_open(gameport, NULL, GAMEPORT_MODE_RAW))
89 		return 0;
90 
91 	tx = ~0;
92 
93 	for (i = 0; i < 50; i++) {
94 		local_irq_save(flags);
95 		t1 = ktime_get_ns();
96 		for (t = 0; t < 50; t++)
97 			gameport_read(gameport);
98 		t2 = ktime_get_ns();
99 		t3 = ktime_get_ns();
100 		local_irq_restore(flags);
101 		udelay(i * 10);
102 		t = (t2 - t1) - (t3 - t2);
103 		if (t < tx)
104 			tx = t;
105 	}
106 
107 	gameport_close(gameport);
108 	t = 1000000 * 50;
109 	if (tx)
110 		t /= tx;
111 	return t;
112 }
113 
114 static int old_gameport_measure_speed(struct gameport *gameport)
115 {
116 #if defined(__i386__)
117 
118 	unsigned int i, t, t1, t2, t3, tx;
119 	unsigned long flags;
120 
121 	if (gameport_open(gameport, NULL, GAMEPORT_MODE_RAW))
122 		return 0;
123 
124 	tx = 1 << 30;
125 
126 	for(i = 0; i < 50; i++) {
127 		local_irq_save(flags);
128 		GET_TIME(t1);
129 		for (t = 0; t < 50; t++) gameport_read(gameport);
130 		GET_TIME(t2);
131 		GET_TIME(t3);
132 		local_irq_restore(flags);
133 		udelay(i * 10);
134 		if ((t = DELTA(t2,t1) - DELTA(t3,t2)) < tx) tx = t;
135 	}
136 
137 	gameport_close(gameport);
138 	return 59659 / (tx < 1 ? 1 : tx);
139 
140 #elif defined (__x86_64__)
141 
142 	unsigned int i, t;
143 	unsigned long tx, t1, t2, flags;
144 
145 	if (gameport_open(gameport, NULL, GAMEPORT_MODE_RAW))
146 		return 0;
147 
148 	tx = 1 << 30;
149 
150 	for(i = 0; i < 50; i++) {
151 		local_irq_save(flags);
152 		t1 = rdtsc();
153 		for (t = 0; t < 50; t++) gameport_read(gameport);
154 		t2 = rdtsc();
155 		local_irq_restore(flags);
156 		udelay(i * 10);
157 		if (t2 - t1 < tx) tx = t2 - t1;
158 	}
159 
160 	gameport_close(gameport);
161 	return (this_cpu_read(cpu_info.loops_per_jiffy) *
162 		(unsigned long)HZ / (1000 / 50)) / (tx < 1 ? 1 : tx);
163 
164 #else
165 
166 	unsigned int j, t = 0;
167 
168 	if (gameport_open(gameport, NULL, GAMEPORT_MODE_RAW))
169 		return 0;
170 
171 	j = jiffies; while (j == jiffies);
172 	j = jiffies; while (j == jiffies) { t++; gameport_read(gameport); }
173 
174 	gameport_close(gameport);
175 	return t * HZ / 1000;
176 
177 #endif
178 }
179 
180 void gameport_start_polling(struct gameport *gameport)
181 {
182 	spin_lock(&gameport->timer_lock);
183 
184 	if (!gameport->poll_cnt++) {
185 		BUG_ON(!gameport->poll_handler);
186 		BUG_ON(!gameport->poll_interval);
187 		mod_timer(&gameport->poll_timer, jiffies + msecs_to_jiffies(gameport->poll_interval));
188 	}
189 
190 	spin_unlock(&gameport->timer_lock);
191 }
192 EXPORT_SYMBOL(gameport_start_polling);
193 
194 void gameport_stop_polling(struct gameport *gameport)
195 {
196 	spin_lock(&gameport->timer_lock);
197 
198 	if (!--gameport->poll_cnt)
199 		del_timer(&gameport->poll_timer);
200 
201 	spin_unlock(&gameport->timer_lock);
202 }
203 EXPORT_SYMBOL(gameport_stop_polling);
204 
205 static void gameport_run_poll_handler(unsigned long d)
206 {
207 	struct gameport *gameport = (struct gameport *)d;
208 
209 	gameport->poll_handler(gameport);
210 	if (gameport->poll_cnt)
211 		mod_timer(&gameport->poll_timer, jiffies + msecs_to_jiffies(gameport->poll_interval));
212 }
213 
214 /*
215  * Basic gameport -> driver core mappings
216  */
217 
218 static int gameport_bind_driver(struct gameport *gameport, struct gameport_driver *drv)
219 {
220 	int error;
221 
222 	gameport->dev.driver = &drv->driver;
223 	if (drv->connect(gameport, drv)) {
224 		gameport->dev.driver = NULL;
225 		return -ENODEV;
226 	}
227 
228 	error = device_bind_driver(&gameport->dev);
229 	if (error) {
230 		dev_warn(&gameport->dev,
231 			 "device_bind_driver() failed for %s (%s) and %s, error: %d\n",
232 			gameport->phys, gameport->name,
233 			drv->description, error);
234 		drv->disconnect(gameport);
235 		gameport->dev.driver = NULL;
236 		return error;
237 	}
238 
239 	return 0;
240 }
241 
242 static void gameport_find_driver(struct gameport *gameport)
243 {
244 	int error;
245 
246 	error = device_attach(&gameport->dev);
247 	if (error < 0)
248 		dev_warn(&gameport->dev,
249 			 "device_attach() failed for %s (%s), error: %d\n",
250 			 gameport->phys, gameport->name, error);
251 }
252 
253 
254 /*
255  * Gameport event processing.
256  */
257 
258 enum gameport_event_type {
259 	GAMEPORT_REGISTER_PORT,
260 	GAMEPORT_ATTACH_DRIVER,
261 };
262 
263 struct gameport_event {
264 	enum gameport_event_type type;
265 	void *object;
266 	struct module *owner;
267 	struct list_head node;
268 };
269 
270 static DEFINE_SPINLOCK(gameport_event_lock);	/* protects gameport_event_list */
271 static LIST_HEAD(gameport_event_list);
272 
273 static struct gameport_event *gameport_get_event(void)
274 {
275 	struct gameport_event *event = NULL;
276 	unsigned long flags;
277 
278 	spin_lock_irqsave(&gameport_event_lock, flags);
279 
280 	if (!list_empty(&gameport_event_list)) {
281 		event = list_first_entry(&gameport_event_list,
282 					 struct gameport_event, node);
283 		list_del_init(&event->node);
284 	}
285 
286 	spin_unlock_irqrestore(&gameport_event_lock, flags);
287 	return event;
288 }
289 
290 static void gameport_free_event(struct gameport_event *event)
291 {
292 	module_put(event->owner);
293 	kfree(event);
294 }
295 
296 static void gameport_remove_duplicate_events(struct gameport_event *event)
297 {
298 	struct gameport_event *e, *next;
299 	unsigned long flags;
300 
301 	spin_lock_irqsave(&gameport_event_lock, flags);
302 
303 	list_for_each_entry_safe(e, next, &gameport_event_list, node) {
304 		if (event->object == e->object) {
305 			/*
306 			 * If this event is of different type we should not
307 			 * look further - we only suppress duplicate events
308 			 * that were sent back-to-back.
309 			 */
310 			if (event->type != e->type)
311 				break;
312 
313 			list_del_init(&e->node);
314 			gameport_free_event(e);
315 		}
316 	}
317 
318 	spin_unlock_irqrestore(&gameport_event_lock, flags);
319 }
320 
321 
322 static void gameport_handle_events(struct work_struct *work)
323 {
324 	struct gameport_event *event;
325 
326 	mutex_lock(&gameport_mutex);
327 
328 	/*
329 	 * Note that we handle only one event here to give swsusp
330 	 * a chance to freeze kgameportd thread. Gameport events
331 	 * should be pretty rare so we are not concerned about
332 	 * taking performance hit.
333 	 */
334 	if ((event = gameport_get_event())) {
335 
336 		switch (event->type) {
337 
338 		case GAMEPORT_REGISTER_PORT:
339 			gameport_add_port(event->object);
340 			break;
341 
342 		case GAMEPORT_ATTACH_DRIVER:
343 			gameport_attach_driver(event->object);
344 			break;
345 		}
346 
347 		gameport_remove_duplicate_events(event);
348 		gameport_free_event(event);
349 	}
350 
351 	mutex_unlock(&gameport_mutex);
352 }
353 
354 static DECLARE_WORK(gameport_event_work, gameport_handle_events);
355 
356 static int gameport_queue_event(void *object, struct module *owner,
357 				enum gameport_event_type event_type)
358 {
359 	unsigned long flags;
360 	struct gameport_event *event;
361 	int retval = 0;
362 
363 	spin_lock_irqsave(&gameport_event_lock, flags);
364 
365 	/*
366 	 * Scan event list for the other events for the same gameport port,
367 	 * starting with the most recent one. If event is the same we
368 	 * do not need add new one. If event is of different type we
369 	 * need to add this event and should not look further because
370 	 * we need to preserve sequence of distinct events.
371 	 */
372 	list_for_each_entry_reverse(event, &gameport_event_list, node) {
373 		if (event->object == object) {
374 			if (event->type == event_type)
375 				goto out;
376 			break;
377 		}
378 	}
379 
380 	event = kmalloc(sizeof(struct gameport_event), GFP_ATOMIC);
381 	if (!event) {
382 		pr_err("Not enough memory to queue event %d\n", event_type);
383 		retval = -ENOMEM;
384 		goto out;
385 	}
386 
387 	if (!try_module_get(owner)) {
388 		pr_warn("Can't get module reference, dropping event %d\n",
389 			event_type);
390 		kfree(event);
391 		retval = -EINVAL;
392 		goto out;
393 	}
394 
395 	event->type = event_type;
396 	event->object = object;
397 	event->owner = owner;
398 
399 	list_add_tail(&event->node, &gameport_event_list);
400 	queue_work(system_long_wq, &gameport_event_work);
401 
402 out:
403 	spin_unlock_irqrestore(&gameport_event_lock, flags);
404 	return retval;
405 }
406 
407 /*
408  * Remove all events that have been submitted for a given object,
409  * be it a gameport port or a driver.
410  */
411 static void gameport_remove_pending_events(void *object)
412 {
413 	struct gameport_event *event, *next;
414 	unsigned long flags;
415 
416 	spin_lock_irqsave(&gameport_event_lock, flags);
417 
418 	list_for_each_entry_safe(event, next, &gameport_event_list, node) {
419 		if (event->object == object) {
420 			list_del_init(&event->node);
421 			gameport_free_event(event);
422 		}
423 	}
424 
425 	spin_unlock_irqrestore(&gameport_event_lock, flags);
426 }
427 
428 /*
429  * Destroy child gameport port (if any) that has not been fully registered yet.
430  *
431  * Note that we rely on the fact that port can have only one child and therefore
432  * only one child registration request can be pending. Additionally, children
433  * are registered by driver's connect() handler so there can't be a grandchild
434  * pending registration together with a child.
435  */
436 static struct gameport *gameport_get_pending_child(struct gameport *parent)
437 {
438 	struct gameport_event *event;
439 	struct gameport *gameport, *child = NULL;
440 	unsigned long flags;
441 
442 	spin_lock_irqsave(&gameport_event_lock, flags);
443 
444 	list_for_each_entry(event, &gameport_event_list, node) {
445 		if (event->type == GAMEPORT_REGISTER_PORT) {
446 			gameport = event->object;
447 			if (gameport->parent == parent) {
448 				child = gameport;
449 				break;
450 			}
451 		}
452 	}
453 
454 	spin_unlock_irqrestore(&gameport_event_lock, flags);
455 	return child;
456 }
457 
458 /*
459  * Gameport port operations
460  */
461 
462 static ssize_t gameport_description_show(struct device *dev, struct device_attribute *attr, char *buf)
463 {
464 	struct gameport *gameport = to_gameport_port(dev);
465 
466 	return sprintf(buf, "%s\n", gameport->name);
467 }
468 static DEVICE_ATTR(description, S_IRUGO, gameport_description_show, NULL);
469 
470 static ssize_t drvctl_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
471 {
472 	struct gameport *gameport = to_gameport_port(dev);
473 	struct device_driver *drv;
474 	int error;
475 
476 	error = mutex_lock_interruptible(&gameport_mutex);
477 	if (error)
478 		return error;
479 
480 	if (!strncmp(buf, "none", count)) {
481 		gameport_disconnect_port(gameport);
482 	} else if (!strncmp(buf, "reconnect", count)) {
483 		gameport_reconnect_port(gameport);
484 	} else if (!strncmp(buf, "rescan", count)) {
485 		gameport_disconnect_port(gameport);
486 		gameport_find_driver(gameport);
487 	} else if ((drv = driver_find(buf, &gameport_bus)) != NULL) {
488 		gameport_disconnect_port(gameport);
489 		error = gameport_bind_driver(gameport, to_gameport_driver(drv));
490 	} else {
491 		error = -EINVAL;
492 	}
493 
494 	mutex_unlock(&gameport_mutex);
495 
496 	return error ? error : count;
497 }
498 static DEVICE_ATTR_WO(drvctl);
499 
500 static struct attribute *gameport_device_attrs[] = {
501 	&dev_attr_description.attr,
502 	&dev_attr_drvctl.attr,
503 	NULL,
504 };
505 ATTRIBUTE_GROUPS(gameport_device);
506 
507 static void gameport_release_port(struct device *dev)
508 {
509 	struct gameport *gameport = to_gameport_port(dev);
510 
511 	kfree(gameport);
512 	module_put(THIS_MODULE);
513 }
514 
515 void gameport_set_phys(struct gameport *gameport, const char *fmt, ...)
516 {
517 	va_list args;
518 
519 	va_start(args, fmt);
520 	vsnprintf(gameport->phys, sizeof(gameport->phys), fmt, args);
521 	va_end(args);
522 }
523 EXPORT_SYMBOL(gameport_set_phys);
524 
525 /*
526  * Prepare gameport port for registration.
527  */
528 static void gameport_init_port(struct gameport *gameport)
529 {
530 	static atomic_t gameport_no = ATOMIC_INIT(-1);
531 
532 	__module_get(THIS_MODULE);
533 
534 	mutex_init(&gameport->drv_mutex);
535 	device_initialize(&gameport->dev);
536 	dev_set_name(&gameport->dev, "gameport%lu",
537 			(unsigned long)atomic_inc_return(&gameport_no));
538 	gameport->dev.bus = &gameport_bus;
539 	gameport->dev.release = gameport_release_port;
540 	if (gameport->parent)
541 		gameport->dev.parent = &gameport->parent->dev;
542 
543 	INIT_LIST_HEAD(&gameport->node);
544 	spin_lock_init(&gameport->timer_lock);
545 	setup_timer(&gameport->poll_timer, gameport_run_poll_handler,
546 		    (unsigned long)gameport);
547 }
548 
549 /*
550  * Complete gameport port registration.
551  * Driver core will attempt to find appropriate driver for the port.
552  */
553 static void gameport_add_port(struct gameport *gameport)
554 {
555 	int error;
556 
557 	if (gameport->parent)
558 		gameport->parent->child = gameport;
559 
560 	gameport->speed = use_ktime ?
561 		gameport_measure_speed(gameport) :
562 		old_gameport_measure_speed(gameport);
563 
564 	list_add_tail(&gameport->node, &gameport_list);
565 
566 	if (gameport->io)
567 		dev_info(&gameport->dev, "%s is %s, io %#x, speed %dkHz\n",
568 			 gameport->name, gameport->phys, gameport->io, gameport->speed);
569 	else
570 		dev_info(&gameport->dev, "%s is %s, speed %dkHz\n",
571 			gameport->name, gameport->phys, gameport->speed);
572 
573 	error = device_add(&gameport->dev);
574 	if (error)
575 		dev_err(&gameport->dev,
576 			"device_add() failed for %s (%s), error: %d\n",
577 			gameport->phys, gameport->name, error);
578 }
579 
580 /*
581  * gameport_destroy_port() completes deregistration process and removes
582  * port from the system
583  */
584 static void gameport_destroy_port(struct gameport *gameport)
585 {
586 	struct gameport *child;
587 
588 	child = gameport_get_pending_child(gameport);
589 	if (child) {
590 		gameport_remove_pending_events(child);
591 		put_device(&child->dev);
592 	}
593 
594 	if (gameport->parent) {
595 		gameport->parent->child = NULL;
596 		gameport->parent = NULL;
597 	}
598 
599 	if (device_is_registered(&gameport->dev))
600 		device_del(&gameport->dev);
601 
602 	list_del_init(&gameport->node);
603 
604 	gameport_remove_pending_events(gameport);
605 	put_device(&gameport->dev);
606 }
607 
608 /*
609  * Reconnect gameport port and all its children (re-initialize attached devices)
610  */
611 static void gameport_reconnect_port(struct gameport *gameport)
612 {
613 	do {
614 		if (!gameport->drv || !gameport->drv->reconnect || gameport->drv->reconnect(gameport)) {
615 			gameport_disconnect_port(gameport);
616 			gameport_find_driver(gameport);
617 			/* Ok, old children are now gone, we are done */
618 			break;
619 		}
620 		gameport = gameport->child;
621 	} while (gameport);
622 }
623 
624 /*
625  * gameport_disconnect_port() unbinds a port from its driver. As a side effect
626  * all child ports are unbound and destroyed.
627  */
628 static void gameport_disconnect_port(struct gameport *gameport)
629 {
630 	struct gameport *s, *parent;
631 
632 	if (gameport->child) {
633 		/*
634 		 * Children ports should be disconnected and destroyed
635 		 * first, staring with the leaf one, since we don't want
636 		 * to do recursion
637 		 */
638 		for (s = gameport; s->child; s = s->child)
639 			/* empty */;
640 
641 		do {
642 			parent = s->parent;
643 
644 			device_release_driver(&s->dev);
645 			gameport_destroy_port(s);
646 		} while ((s = parent) != gameport);
647 	}
648 
649 	/*
650 	 * Ok, no children left, now disconnect this port
651 	 */
652 	device_release_driver(&gameport->dev);
653 }
654 
655 /*
656  * Submits register request to kgameportd for subsequent execution.
657  * Note that port registration is always asynchronous.
658  */
659 void __gameport_register_port(struct gameport *gameport, struct module *owner)
660 {
661 	gameport_init_port(gameport);
662 	gameport_queue_event(gameport, owner, GAMEPORT_REGISTER_PORT);
663 }
664 EXPORT_SYMBOL(__gameport_register_port);
665 
666 /*
667  * Synchronously unregisters gameport port.
668  */
669 void gameport_unregister_port(struct gameport *gameport)
670 {
671 	mutex_lock(&gameport_mutex);
672 	gameport_disconnect_port(gameport);
673 	gameport_destroy_port(gameport);
674 	mutex_unlock(&gameport_mutex);
675 }
676 EXPORT_SYMBOL(gameport_unregister_port);
677 
678 
679 /*
680  * Gameport driver operations
681  */
682 
683 static ssize_t description_show(struct device_driver *drv, char *buf)
684 {
685 	struct gameport_driver *driver = to_gameport_driver(drv);
686 	return sprintf(buf, "%s\n", driver->description ? driver->description : "(none)");
687 }
688 static DRIVER_ATTR_RO(description);
689 
690 static struct attribute *gameport_driver_attrs[] = {
691 	&driver_attr_description.attr,
692 	NULL
693 };
694 ATTRIBUTE_GROUPS(gameport_driver);
695 
696 static int gameport_driver_probe(struct device *dev)
697 {
698 	struct gameport *gameport = to_gameport_port(dev);
699 	struct gameport_driver *drv = to_gameport_driver(dev->driver);
700 
701 	drv->connect(gameport, drv);
702 	return gameport->drv ? 0 : -ENODEV;
703 }
704 
705 static int gameport_driver_remove(struct device *dev)
706 {
707 	struct gameport *gameport = to_gameport_port(dev);
708 	struct gameport_driver *drv = to_gameport_driver(dev->driver);
709 
710 	drv->disconnect(gameport);
711 	return 0;
712 }
713 
714 static void gameport_attach_driver(struct gameport_driver *drv)
715 {
716 	int error;
717 
718 	error = driver_attach(&drv->driver);
719 	if (error)
720 		pr_err("driver_attach() failed for %s, error: %d\n",
721 			drv->driver.name, error);
722 }
723 
724 int __gameport_register_driver(struct gameport_driver *drv, struct module *owner,
725 				const char *mod_name)
726 {
727 	int error;
728 
729 	drv->driver.bus = &gameport_bus;
730 	drv->driver.owner = owner;
731 	drv->driver.mod_name = mod_name;
732 
733 	/*
734 	 * Temporarily disable automatic binding because probing
735 	 * takes long time and we are better off doing it in kgameportd
736 	 */
737 	drv->ignore = true;
738 
739 	error = driver_register(&drv->driver);
740 	if (error) {
741 		pr_err("driver_register() failed for %s, error: %d\n",
742 			drv->driver.name, error);
743 		return error;
744 	}
745 
746 	/*
747 	 * Reset ignore flag and let kgameportd bind the driver to free ports
748 	 */
749 	drv->ignore = false;
750 	error = gameport_queue_event(drv, NULL, GAMEPORT_ATTACH_DRIVER);
751 	if (error) {
752 		driver_unregister(&drv->driver);
753 		return error;
754 	}
755 
756 	return 0;
757 }
758 EXPORT_SYMBOL(__gameport_register_driver);
759 
760 void gameport_unregister_driver(struct gameport_driver *drv)
761 {
762 	struct gameport *gameport;
763 
764 	mutex_lock(&gameport_mutex);
765 
766 	drv->ignore = true;	/* so gameport_find_driver ignores it */
767 	gameport_remove_pending_events(drv);
768 
769 start_over:
770 	list_for_each_entry(gameport, &gameport_list, node) {
771 		if (gameport->drv == drv) {
772 			gameport_disconnect_port(gameport);
773 			gameport_find_driver(gameport);
774 			/* we could've deleted some ports, restart */
775 			goto start_over;
776 		}
777 	}
778 
779 	driver_unregister(&drv->driver);
780 
781 	mutex_unlock(&gameport_mutex);
782 }
783 EXPORT_SYMBOL(gameport_unregister_driver);
784 
785 static int gameport_bus_match(struct device *dev, struct device_driver *drv)
786 {
787 	struct gameport_driver *gameport_drv = to_gameport_driver(drv);
788 
789 	return !gameport_drv->ignore;
790 }
791 
792 static struct bus_type gameport_bus = {
793 	.name		= "gameport",
794 	.dev_groups	= gameport_device_groups,
795 	.drv_groups	= gameport_driver_groups,
796 	.match		= gameport_bus_match,
797 	.probe		= gameport_driver_probe,
798 	.remove		= gameport_driver_remove,
799 };
800 
801 static void gameport_set_drv(struct gameport *gameport, struct gameport_driver *drv)
802 {
803 	mutex_lock(&gameport->drv_mutex);
804 	gameport->drv = drv;
805 	mutex_unlock(&gameport->drv_mutex);
806 }
807 
808 int gameport_open(struct gameport *gameport, struct gameport_driver *drv, int mode)
809 {
810 	if (gameport->open) {
811 		if (gameport->open(gameport, mode)) {
812 			return -1;
813 		}
814 	} else {
815 		if (mode != GAMEPORT_MODE_RAW)
816 			return -1;
817 	}
818 
819 	gameport_set_drv(gameport, drv);
820 	return 0;
821 }
822 EXPORT_SYMBOL(gameport_open);
823 
824 void gameport_close(struct gameport *gameport)
825 {
826 	del_timer_sync(&gameport->poll_timer);
827 	gameport->poll_handler = NULL;
828 	gameport->poll_interval = 0;
829 	gameport_set_drv(gameport, NULL);
830 	if (gameport->close)
831 		gameport->close(gameport);
832 }
833 EXPORT_SYMBOL(gameport_close);
834 
835 static int __init gameport_init(void)
836 {
837 	int error;
838 
839 	error = bus_register(&gameport_bus);
840 	if (error) {
841 		pr_err("failed to register gameport bus, error: %d\n", error);
842 		return error;
843 	}
844 
845 
846 	return 0;
847 }
848 
849 static void __exit gameport_exit(void)
850 {
851 	bus_unregister(&gameport_bus);
852 
853 	/*
854 	 * There should not be any outstanding events but work may
855 	 * still be scheduled so simply cancel it.
856 	 */
857 	cancel_work_sync(&gameport_event_work);
858 }
859 
860 subsys_initcall(gameport_init);
861 module_exit(gameport_exit);
862