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