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