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