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_rescan);
40 EXPORT_SYMBOL(gameport_set_phys);
41 EXPORT_SYMBOL(gameport_start_polling);
42 EXPORT_SYMBOL(gameport_stop_polling);
43 
44 /*
45  * gameport_mutex protects entire gameport subsystem and is taken
46  * every time gameport port or driver registrered or unregistered.
47  */
48 static DEFINE_MUTEX(gameport_mutex);
49 
50 static LIST_HEAD(gameport_list);
51 
52 static struct bus_type gameport_bus;
53 
54 static void gameport_add_driver(struct gameport_driver *drv);
55 static void gameport_add_port(struct gameport *gameport);
56 static void gameport_destroy_port(struct gameport *gameport);
57 static void gameport_reconnect_port(struct gameport *gameport);
58 static void gameport_disconnect_port(struct gameport *gameport);
59 
60 #if defined(__i386__)
61 
62 #include <asm/i8253.h>
63 
64 #define DELTA(x,y)      ((y)-(x)+((y)<(x)?1193182/HZ:0))
65 #define GET_TIME(x)     do { x = get_time_pit(); } while (0)
66 
67 static unsigned int get_time_pit(void)
68 {
69 	unsigned long flags;
70 	unsigned int count;
71 
72 	spin_lock_irqsave(&i8253_lock, flags);
73 	outb_p(0x00, 0x43);
74 	count = inb_p(0x40);
75 	count |= inb_p(0x40) << 8;
76 	spin_unlock_irqrestore(&i8253_lock, flags);
77 
78 	return count;
79 }
80 
81 #endif
82 
83 
84 
85 /*
86  * gameport_measure_speed() measures the gameport i/o speed.
87  */
88 
89 static int gameport_measure_speed(struct gameport *gameport)
90 {
91 #if defined(__i386__)
92 
93 	unsigned int i, t, t1, t2, t3, tx;
94 	unsigned long flags;
95 
96 	if (gameport_open(gameport, NULL, GAMEPORT_MODE_RAW))
97 		return 0;
98 
99 	tx = 1 << 30;
100 
101 	for(i = 0; i < 50; i++) {
102 		local_irq_save(flags);
103 		GET_TIME(t1);
104 		for (t = 0; t < 50; t++) gameport_read(gameport);
105 		GET_TIME(t2);
106 		GET_TIME(t3);
107 		local_irq_restore(flags);
108 		udelay(i * 10);
109 		if ((t = DELTA(t2,t1) - DELTA(t3,t2)) < tx) tx = t;
110 	}
111 
112 	gameport_close(gameport);
113 	return 59659 / (tx < 1 ? 1 : tx);
114 
115 #elif defined (__x86_64__)
116 
117 	unsigned int i, t;
118 	unsigned long tx, t1, t2, flags;
119 
120 	if (gameport_open(gameport, NULL, GAMEPORT_MODE_RAW))
121 		return 0;
122 
123 	tx = 1 << 30;
124 
125 	for(i = 0; i < 50; i++) {
126 		local_irq_save(flags);
127 		rdtscl(t1);
128 		for (t = 0; t < 50; t++) gameport_read(gameport);
129 		rdtscl(t2);
130 		local_irq_restore(flags);
131 		udelay(i * 10);
132 		if (t2 - t1 < tx) tx = t2 - t1;
133 	}
134 
135 	gameport_close(gameport);
136 	return (cpu_data(raw_smp_processor_id()).loops_per_jiffy *
137 		(unsigned long)HZ / (1000 / 50)) / (tx < 1 ? 1 : tx);
138 
139 #else
140 
141 	unsigned int j, t = 0;
142 
143 	if (gameport_open(gameport, NULL, GAMEPORT_MODE_RAW))
144 		return 0;
145 
146 	j = jiffies; while (j == jiffies);
147 	j = jiffies; while (j == jiffies) { t++; gameport_read(gameport); }
148 
149 	gameport_close(gameport);
150 	return t * HZ / 1000;
151 
152 #endif
153 }
154 
155 void gameport_start_polling(struct gameport *gameport)
156 {
157 	spin_lock(&gameport->timer_lock);
158 
159 	if (!gameport->poll_cnt++) {
160 		BUG_ON(!gameport->poll_handler);
161 		BUG_ON(!gameport->poll_interval);
162 		mod_timer(&gameport->poll_timer, jiffies + msecs_to_jiffies(gameport->poll_interval));
163 	}
164 
165 	spin_unlock(&gameport->timer_lock);
166 }
167 
168 void gameport_stop_polling(struct gameport *gameport)
169 {
170 	spin_lock(&gameport->timer_lock);
171 
172 	if (!--gameport->poll_cnt)
173 		del_timer(&gameport->poll_timer);
174 
175 	spin_unlock(&gameport->timer_lock);
176 }
177 
178 static void gameport_run_poll_handler(unsigned long d)
179 {
180 	struct gameport *gameport = (struct gameport *)d;
181 
182 	gameport->poll_handler(gameport);
183 	if (gameport->poll_cnt)
184 		mod_timer(&gameport->poll_timer, jiffies + msecs_to_jiffies(gameport->poll_interval));
185 }
186 
187 /*
188  * Basic gameport -> driver core mappings
189  */
190 
191 static int gameport_bind_driver(struct gameport *gameport, struct gameport_driver *drv)
192 {
193 	int error;
194 
195 	gameport->dev.driver = &drv->driver;
196 	if (drv->connect(gameport, drv)) {
197 		gameport->dev.driver = NULL;
198 		return -ENODEV;
199 	}
200 
201 	error = device_bind_driver(&gameport->dev);
202 	if (error) {
203 		printk(KERN_WARNING
204 			"gameport: device_bind_driver() failed "
205 			"for %s (%s) and %s, error: %d\n",
206 			gameport->phys, gameport->name,
207 			drv->description, error);
208 		drv->disconnect(gameport);
209 		gameport->dev.driver = NULL;
210 		return error;
211 	}
212 
213 	return 0;
214 }
215 
216 static void gameport_find_driver(struct gameport *gameport)
217 {
218 	int error;
219 
220 	error = device_attach(&gameport->dev);
221 	if (error < 0)
222 		printk(KERN_WARNING
223 			"gameport: device_attach() failed for %s (%s), error: %d\n",
224 			gameport->phys, gameport->name, error);
225 }
226 
227 
228 /*
229  * Gameport event processing.
230  */
231 
232 enum gameport_event_type {
233 	GAMEPORT_RESCAN,
234 	GAMEPORT_RECONNECT,
235 	GAMEPORT_REGISTER_PORT,
236 	GAMEPORT_REGISTER_DRIVER,
237 };
238 
239 struct gameport_event {
240 	enum gameport_event_type type;
241 	void *object;
242 	struct module *owner;
243 	struct list_head node;
244 };
245 
246 static DEFINE_SPINLOCK(gameport_event_lock);	/* protects gameport_event_list */
247 static LIST_HEAD(gameport_event_list);
248 static DECLARE_WAIT_QUEUE_HEAD(gameport_wait);
249 static struct task_struct *gameport_task;
250 
251 static void gameport_queue_event(void *object, struct module *owner,
252 			      enum gameport_event_type event_type)
253 {
254 	unsigned long flags;
255 	struct gameport_event *event;
256 
257 	spin_lock_irqsave(&gameport_event_lock, flags);
258 
259 	/*
260 	 * Scan event list for the other events for the same gameport port,
261 	 * starting with the most recent one. If event is the same we
262 	 * do not need add new one. If event is of different type we
263 	 * need to add this event and should not look further because
264 	 * we need to preseve sequence of distinct events.
265 	 */
266 	list_for_each_entry_reverse(event, &gameport_event_list, node) {
267 		if (event->object == object) {
268 			if (event->type == event_type)
269 				goto out;
270 			break;
271 		}
272 	}
273 
274 	if ((event = kmalloc(sizeof(struct gameport_event), GFP_ATOMIC))) {
275 		if (!try_module_get(owner)) {
276 			printk(KERN_WARNING "gameport: Can't get module reference, dropping event %d\n", event_type);
277 			kfree(event);
278 			goto out;
279 		}
280 
281 		event->type = event_type;
282 		event->object = object;
283 		event->owner = owner;
284 
285 		list_add_tail(&event->node, &gameport_event_list);
286 		wake_up(&gameport_wait);
287 	} else {
288 		printk(KERN_ERR "gameport: Not enough memory to queue event %d\n", event_type);
289 	}
290 out:
291 	spin_unlock_irqrestore(&gameport_event_lock, flags);
292 }
293 
294 static void gameport_free_event(struct gameport_event *event)
295 {
296 	module_put(event->owner);
297 	kfree(event);
298 }
299 
300 static void gameport_remove_duplicate_events(struct gameport_event *event)
301 {
302 	struct list_head *node, *next;
303 	struct gameport_event *e;
304 	unsigned long flags;
305 
306 	spin_lock_irqsave(&gameport_event_lock, flags);
307 
308 	list_for_each_safe(node, next, &gameport_event_list) {
309 		e = list_entry(node, struct gameport_event, node);
310 		if (event->object == e->object) {
311 			/*
312 			 * If this event is of different type we should not
313 			 * look further - we only suppress duplicate events
314 			 * that were sent back-to-back.
315 			 */
316 			if (event->type != e->type)
317 				break;
318 
319 			list_del_init(node);
320 			gameport_free_event(e);
321 		}
322 	}
323 
324 	spin_unlock_irqrestore(&gameport_event_lock, flags);
325 }
326 
327 static struct gameport_event *gameport_get_event(void)
328 {
329 	struct gameport_event *event;
330 	struct list_head *node;
331 	unsigned long flags;
332 
333 	spin_lock_irqsave(&gameport_event_lock, flags);
334 
335 	if (list_empty(&gameport_event_list)) {
336 		spin_unlock_irqrestore(&gameport_event_lock, flags);
337 		return NULL;
338 	}
339 
340 	node = gameport_event_list.next;
341 	event = list_entry(node, struct gameport_event, node);
342 	list_del_init(node);
343 
344 	spin_unlock_irqrestore(&gameport_event_lock, flags);
345 
346 	return event;
347 }
348 
349 static void gameport_handle_event(void)
350 {
351 	struct gameport_event *event;
352 
353 	mutex_lock(&gameport_mutex);
354 
355 	/*
356 	 * Note that we handle only one event here to give swsusp
357 	 * a chance to freeze kgameportd thread. Gameport events
358 	 * should be pretty rare so we are not concerned about
359 	 * taking performance hit.
360 	 */
361 	if ((event = gameport_get_event())) {
362 
363 		switch (event->type) {
364 			case GAMEPORT_REGISTER_PORT:
365 				gameport_add_port(event->object);
366 				break;
367 
368 			case GAMEPORT_RECONNECT:
369 				gameport_reconnect_port(event->object);
370 				break;
371 
372 			case GAMEPORT_RESCAN:
373 				gameport_disconnect_port(event->object);
374 				gameport_find_driver(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 gameport port.
394  */
395 static void gameport_remove_pending_events(struct gameport *gameport)
396 {
397 	struct list_head *node, *next;
398 	struct gameport_event *event;
399 	unsigned long flags;
400 
401 	spin_lock_irqsave(&gameport_event_lock, flags);
402 
403 	list_for_each_safe(node, next, &gameport_event_list) {
404 		event = list_entry(node, struct gameport_event, node);
405 		if (event->object == gameport) {
406 			list_del_init(node);
407 			gameport_free_event(event);
408 		}
409 	}
410 
411 	spin_unlock_irqrestore(&gameport_event_lock, flags);
412 }
413 
414 /*
415  * Destroy child gameport port (if any) that has not been fully registered yet.
416  *
417  * Note that we rely on the fact that port can have only one child and therefore
418  * only one child registration request can be pending. Additionally, children
419  * are registered by driver's connect() handler so there can't be a grandchild
420  * pending registration together with a child.
421  */
422 static struct gameport *gameport_get_pending_child(struct gameport *parent)
423 {
424 	struct gameport_event *event;
425 	struct gameport *gameport, *child = NULL;
426 	unsigned long flags;
427 
428 	spin_lock_irqsave(&gameport_event_lock, flags);
429 
430 	list_for_each_entry(event, &gameport_event_list, node) {
431 		if (event->type == GAMEPORT_REGISTER_PORT) {
432 			gameport = event->object;
433 			if (gameport->parent == parent) {
434 				child = gameport;
435 				break;
436 			}
437 		}
438 	}
439 
440 	spin_unlock_irqrestore(&gameport_event_lock, flags);
441 	return child;
442 }
443 
444 static int gameport_thread(void *nothing)
445 {
446 	set_freezable();
447 	do {
448 		gameport_handle_event();
449 		wait_event_freezable(gameport_wait,
450 			kthread_should_stop() || !list_empty(&gameport_event_list));
451 	} while (!kthread_should_stop());
452 
453 	printk(KERN_DEBUG "gameport: kgameportd exiting\n");
454 	return 0;
455 }
456 
457 
458 /*
459  * Gameport port operations
460  */
461 
462 static ssize_t gameport_show_description(struct device *dev, struct device_attribute *attr, char *buf)
463 {
464 	struct gameport *gameport = to_gameport_port(dev);
465 	return sprintf(buf, "%s\n", gameport->name);
466 }
467 
468 static ssize_t gameport_rebind_driver(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
469 {
470 	struct gameport *gameport = to_gameport_port(dev);
471 	struct device_driver *drv;
472 	int error;
473 
474 	error = mutex_lock_interruptible(&gameport_mutex);
475 	if (error)
476 		return error;
477 
478 	if (!strncmp(buf, "none", count)) {
479 		gameport_disconnect_port(gameport);
480 	} else if (!strncmp(buf, "reconnect", count)) {
481 		gameport_reconnect_port(gameport);
482 	} else if (!strncmp(buf, "rescan", count)) {
483 		gameport_disconnect_port(gameport);
484 		gameport_find_driver(gameport);
485 	} else if ((drv = driver_find(buf, &gameport_bus)) != NULL) {
486 		gameport_disconnect_port(gameport);
487 		error = gameport_bind_driver(gameport, to_gameport_driver(drv));
488 		put_driver(drv);
489 	} else {
490 		error = -EINVAL;
491 	}
492 
493 	mutex_unlock(&gameport_mutex);
494 
495 	return error ? error : count;
496 }
497 
498 static struct device_attribute gameport_device_attrs[] = {
499 	__ATTR(description, S_IRUGO, gameport_show_description, NULL),
500 	__ATTR(drvctl, S_IWUSR, NULL, gameport_rebind_driver),
501 	__ATTR_NULL
502 };
503 
504 static void gameport_release_port(struct device *dev)
505 {
506 	struct gameport *gameport = to_gameport_port(dev);
507 
508 	kfree(gameport);
509 	module_put(THIS_MODULE);
510 }
511 
512 void gameport_set_phys(struct gameport *gameport, const char *fmt, ...)
513 {
514 	va_list args;
515 
516 	va_start(args, fmt);
517 	vsnprintf(gameport->phys, sizeof(gameport->phys), fmt, args);
518 	va_end(args);
519 }
520 
521 /*
522  * Prepare gameport port for registration.
523  */
524 static void gameport_init_port(struct gameport *gameport)
525 {
526 	static atomic_t gameport_no = ATOMIC_INIT(0);
527 
528 	__module_get(THIS_MODULE);
529 
530 	mutex_init(&gameport->drv_mutex);
531 	device_initialize(&gameport->dev);
532 	snprintf(gameport->dev.bus_id, sizeof(gameport->dev.bus_id),
533 		 "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 void gameport_rescan(struct gameport *gameport)
655 {
656 	gameport_queue_event(gameport, NULL, GAMEPORT_RESCAN);
657 }
658 
659 void gameport_reconnect(struct gameport *gameport)
660 {
661 	gameport_queue_event(gameport, NULL, GAMEPORT_RECONNECT);
662 }
663 
664 /*
665  * Submits register request to kgameportd for subsequent execution.
666  * Note that port registration is always asynchronous.
667  */
668 void __gameport_register_port(struct gameport *gameport, struct module *owner)
669 {
670 	gameport_init_port(gameport);
671 	gameport_queue_event(gameport, owner, GAMEPORT_REGISTER_PORT);
672 }
673 
674 /*
675  * Synchronously unregisters gameport port.
676  */
677 void gameport_unregister_port(struct gameport *gameport)
678 {
679 	mutex_lock(&gameport_mutex);
680 	gameport_disconnect_port(gameport);
681 	gameport_destroy_port(gameport);
682 	mutex_unlock(&gameport_mutex);
683 }
684 
685 
686 /*
687  * Gameport driver operations
688  */
689 
690 static ssize_t gameport_driver_show_description(struct device_driver *drv, char *buf)
691 {
692 	struct gameport_driver *driver = to_gameport_driver(drv);
693 	return sprintf(buf, "%s\n", driver->description ? driver->description : "(none)");
694 }
695 
696 static struct driver_attribute gameport_driver_attrs[] = {
697 	__ATTR(description, S_IRUGO, gameport_driver_show_description, NULL),
698 	__ATTR_NULL
699 };
700 
701 static int gameport_driver_probe(struct device *dev)
702 {
703 	struct gameport *gameport = to_gameport_port(dev);
704 	struct gameport_driver *drv = to_gameport_driver(dev->driver);
705 
706 	drv->connect(gameport, drv);
707 	return gameport->drv ? 0 : -ENODEV;
708 }
709 
710 static int gameport_driver_remove(struct device *dev)
711 {
712 	struct gameport *gameport = to_gameport_port(dev);
713 	struct gameport_driver *drv = to_gameport_driver(dev->driver);
714 
715 	drv->disconnect(gameport);
716 	return 0;
717 }
718 
719 static void gameport_add_driver(struct gameport_driver *drv)
720 {
721 	int error;
722 
723 	error = driver_register(&drv->driver);
724 	if (error)
725 		printk(KERN_ERR
726 			"gameport: driver_register() failed for %s, error: %d\n",
727 			drv->driver.name, error);
728 }
729 
730 void __gameport_register_driver(struct gameport_driver *drv, struct module *owner)
731 {
732 	drv->driver.bus = &gameport_bus;
733 	gameport_queue_event(drv, owner, GAMEPORT_REGISTER_DRIVER);
734 }
735 
736 void gameport_unregister_driver(struct gameport_driver *drv)
737 {
738 	struct gameport *gameport;
739 
740 	mutex_lock(&gameport_mutex);
741 	drv->ignore = 1;	/* so gameport_find_driver ignores it */
742 
743 start_over:
744 	list_for_each_entry(gameport, &gameport_list, node) {
745 		if (gameport->drv == drv) {
746 			gameport_disconnect_port(gameport);
747 			gameport_find_driver(gameport);
748 			/* we could've deleted some ports, restart */
749 			goto start_over;
750 		}
751 	}
752 
753 	driver_unregister(&drv->driver);
754 	mutex_unlock(&gameport_mutex);
755 }
756 
757 static int gameport_bus_match(struct device *dev, struct device_driver *drv)
758 {
759 	struct gameport_driver *gameport_drv = to_gameport_driver(drv);
760 
761 	return !gameport_drv->ignore;
762 }
763 
764 static struct bus_type gameport_bus = {
765 	.name		= "gameport",
766 	.dev_attrs	= gameport_device_attrs,
767 	.drv_attrs	= gameport_driver_attrs,
768 	.match		= gameport_bus_match,
769 	.probe		= gameport_driver_probe,
770 	.remove		= gameport_driver_remove,
771 };
772 
773 static void gameport_set_drv(struct gameport *gameport, struct gameport_driver *drv)
774 {
775 	mutex_lock(&gameport->drv_mutex);
776 	gameport->drv = drv;
777 	mutex_unlock(&gameport->drv_mutex);
778 }
779 
780 int gameport_open(struct gameport *gameport, struct gameport_driver *drv, int mode)
781 {
782 	if (gameport->open) {
783 		if (gameport->open(gameport, mode)) {
784 			return -1;
785 		}
786 	} else {
787 		if (mode != GAMEPORT_MODE_RAW)
788 			return -1;
789 	}
790 
791 	gameport_set_drv(gameport, drv);
792 	return 0;
793 }
794 
795 void gameport_close(struct gameport *gameport)
796 {
797 	del_timer_sync(&gameport->poll_timer);
798 	gameport->poll_handler = NULL;
799 	gameport->poll_interval = 0;
800 	gameport_set_drv(gameport, NULL);
801 	if (gameport->close)
802 		gameport->close(gameport);
803 }
804 
805 static int __init gameport_init(void)
806 {
807 	int error;
808 
809 	error = bus_register(&gameport_bus);
810 	if (error) {
811 		printk(KERN_ERR "gameport: failed to register gameport bus, error: %d\n", error);
812 		return error;
813 	}
814 
815 	gameport_task = kthread_run(gameport_thread, NULL, "kgameportd");
816 	if (IS_ERR(gameport_task)) {
817 		bus_unregister(&gameport_bus);
818 		error = PTR_ERR(gameport_task);
819 		printk(KERN_ERR "gameport: Failed to start kgameportd, error: %d\n", error);
820 		return error;
821 	}
822 
823 	return 0;
824 }
825 
826 static void __exit gameport_exit(void)
827 {
828 	bus_unregister(&gameport_bus);
829 	kthread_stop(gameport_task);
830 }
831 
832 subsys_initcall(gameport_init);
833 module_exit(gameport_exit);
834