Manual merge with Linus.
[linux-2.6.git] / drivers / input / gameport / gameport.c
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
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_cooked_read);
41 EXPORT_SYMBOL(gameport_set_name);
42 EXPORT_SYMBOL(gameport_set_phys);
43 EXPORT_SYMBOL(gameport_start_polling);
44 EXPORT_SYMBOL(gameport_stop_polling);
45
46 /*
47  * gameport_mutex protects entire gameport subsystem and is taken
48  * every time gameport port or driver registrered or unregistered.
49  */
50 static DEFINE_MUTEX(gameport_mutex);
51
52 static LIST_HEAD(gameport_list);
53
54 static struct bus_type gameport_bus;
55
56 static void gameport_add_port(struct gameport *gameport);
57 static void gameport_destroy_port(struct gameport *gameport);
58 static void gameport_reconnect_port(struct gameport *gameport);
59 static void gameport_disconnect_port(struct gameport *gameport);
60
61 #if defined(__i386__)
62
63 #include <asm/i8253.h>
64
65 #define DELTA(x,y)      ((y)-(x)+((y)<(x)?1193182/HZ:0))
66 #define GET_TIME(x)     do { x = get_time_pit(); } while (0)
67
68 static unsigned int get_time_pit(void)
69 {
70         unsigned long flags;
71         unsigned int count;
72
73         spin_lock_irqsave(&i8253_lock, flags);
74         outb_p(0x00, 0x43);
75         count = inb_p(0x40);
76         count |= inb_p(0x40) << 8;
77         spin_unlock_irqrestore(&i8253_lock, flags);
78
79         return count;
80 }
81
82 #endif
83
84
85
86 /*
87  * gameport_measure_speed() measures the gameport i/o speed.
88  */
89
90 static int gameport_measure_speed(struct gameport *gameport)
91 {
92 #if defined(__i386__)
93
94         unsigned int i, t, t1, t2, t3, tx;
95         unsigned long flags;
96
97         if (gameport_open(gameport, NULL, GAMEPORT_MODE_RAW))
98                 return 0;
99
100         tx = 1 << 30;
101
102         for(i = 0; i < 50; i++) {
103                 local_irq_save(flags);
104                 GET_TIME(t1);
105                 for (t = 0; t < 50; t++) gameport_read(gameport);
106                 GET_TIME(t2);
107                 GET_TIME(t3);
108                 local_irq_restore(flags);
109                 udelay(i * 10);
110                 if ((t = DELTA(t2,t1) - DELTA(t3,t2)) < tx) tx = t;
111         }
112
113         gameport_close(gameport);
114         return 59659 / (tx < 1 ? 1 : tx);
115
116 #elif defined (__x86_64__)
117
118         unsigned int i, t;
119         unsigned long tx, t1, t2, flags;
120
121         if (gameport_open(gameport, NULL, GAMEPORT_MODE_RAW))
122                 return 0;
123
124         tx = 1 << 30;
125
126         for(i = 0; i < 50; i++) {
127                 local_irq_save(flags);
128                 rdtscl(t1);
129                 for (t = 0; t < 50; t++) gameport_read(gameport);
130                 rdtscl(t2);
131                 local_irq_restore(flags);
132                 udelay(i * 10);
133                 if (t2 - t1 < tx) tx = t2 - t1;
134         }
135
136         gameport_close(gameport);
137         return (cpu_data[raw_smp_processor_id()].loops_per_jiffy * (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 void gameport_bind_driver(struct gameport *gameport, struct gameport_driver *drv)
192 {
193         down_write(&gameport_bus.subsys.rwsem);
194
195         gameport->dev.driver = &drv->driver;
196         if (drv->connect(gameport, drv)) {
197                 gameport->dev.driver = NULL;
198                 goto out;
199         }
200         device_bind_driver(&gameport->dev);
201 out:
202         up_write(&gameport_bus.subsys.rwsem);
203 }
204
205 static void gameport_release_driver(struct gameport *gameport)
206 {
207         down_write(&gameport_bus.subsys.rwsem);
208         device_release_driver(&gameport->dev);
209         up_write(&gameport_bus.subsys.rwsem);
210 }
211
212 static void gameport_find_driver(struct gameport *gameport)
213 {
214         down_write(&gameport_bus.subsys.rwsem);
215         device_attach(&gameport->dev);
216         up_write(&gameport_bus.subsys.rwsem);
217 }
218
219
220 /*
221  * Gameport event processing.
222  */
223
224 enum gameport_event_type {
225         GAMEPORT_RESCAN,
226         GAMEPORT_RECONNECT,
227         GAMEPORT_REGISTER_PORT,
228         GAMEPORT_REGISTER_DRIVER,
229 };
230
231 struct gameport_event {
232         enum gameport_event_type type;
233         void *object;
234         struct module *owner;
235         struct list_head node;
236 };
237
238 static DEFINE_SPINLOCK(gameport_event_lock);    /* protects gameport_event_list */
239 static LIST_HEAD(gameport_event_list);
240 static DECLARE_WAIT_QUEUE_HEAD(gameport_wait);
241 static struct task_struct *gameport_task;
242
243 static void gameport_queue_event(void *object, struct module *owner,
244                               enum gameport_event_type event_type)
245 {
246         unsigned long flags;
247         struct gameport_event *event;
248
249         spin_lock_irqsave(&gameport_event_lock, flags);
250
251         /*
252          * Scan event list for the other events for the same gameport port,
253          * starting with the most recent one. If event is the same we
254          * do not need add new one. If event is of different type we
255          * need to add this event and should not look further because
256          * we need to preseve sequence of distinct events.
257          */
258         list_for_each_entry_reverse(event, &gameport_event_list, node) {
259                 if (event->object == object) {
260                         if (event->type == event_type)
261                                 goto out;
262                         break;
263                 }
264         }
265
266         if ((event = kmalloc(sizeof(struct gameport_event), GFP_ATOMIC))) {
267                 if (!try_module_get(owner)) {
268                         printk(KERN_WARNING "gameport: Can't get module reference, dropping event %d\n", event_type);
269                         kfree(event);
270                         goto out;
271                 }
272
273                 event->type = event_type;
274                 event->object = object;
275                 event->owner = owner;
276
277                 list_add_tail(&event->node, &gameport_event_list);
278                 wake_up(&gameport_wait);
279         } else {
280                 printk(KERN_ERR "gameport: Not enough memory to queue event %d\n", event_type);
281         }
282 out:
283         spin_unlock_irqrestore(&gameport_event_lock, flags);
284 }
285
286 static void gameport_free_event(struct gameport_event *event)
287 {
288         module_put(event->owner);
289         kfree(event);
290 }
291
292 static void gameport_remove_duplicate_events(struct gameport_event *event)
293 {
294         struct list_head *node, *next;
295         struct gameport_event *e;
296         unsigned long flags;
297
298         spin_lock_irqsave(&gameport_event_lock, flags);
299
300         list_for_each_safe(node, next, &gameport_event_list) {
301                 e = list_entry(node, struct gameport_event, node);
302                 if (event->object == e->object) {
303                         /*
304                          * If this event is of different type we should not
305                          * look further - we only suppress duplicate events
306                          * that were sent back-to-back.
307                          */
308                         if (event->type != e->type)
309                                 break;
310
311                         list_del_init(node);
312                         gameport_free_event(e);
313                 }
314         }
315
316         spin_unlock_irqrestore(&gameport_event_lock, flags);
317 }
318
319
320 static struct gameport_event *gameport_get_event(void)
321 {
322         struct gameport_event *event;
323         struct list_head *node;
324         unsigned long flags;
325
326         spin_lock_irqsave(&gameport_event_lock, flags);
327
328         if (list_empty(&gameport_event_list)) {
329                 spin_unlock_irqrestore(&gameport_event_lock, flags);
330                 return NULL;
331         }
332
333         node = gameport_event_list.next;
334         event = list_entry(node, struct gameport_event, node);
335         list_del_init(node);
336
337         spin_unlock_irqrestore(&gameport_event_lock, flags);
338
339         return event;
340 }
341
342 static void gameport_handle_event(void)
343 {
344         struct gameport_event *event;
345         struct gameport_driver *gameport_drv;
346
347         mutex_lock(&gameport_mutex);
348
349         /*
350          * Note that we handle only one event here to give swsusp
351          * a chance to freeze kgameportd thread. Gameport events
352          * should be pretty rare so we are not concerned about
353          * taking performance hit.
354          */
355         if ((event = gameport_get_event())) {
356
357                 switch (event->type) {
358                         case GAMEPORT_REGISTER_PORT:
359                                 gameport_add_port(event->object);
360                                 break;
361
362                         case GAMEPORT_RECONNECT:
363                                 gameport_reconnect_port(event->object);
364                                 break;
365
366                         case GAMEPORT_RESCAN:
367                                 gameport_disconnect_port(event->object);
368                                 gameport_find_driver(event->object);
369                                 break;
370
371                         case GAMEPORT_REGISTER_DRIVER:
372                                 gameport_drv = event->object;
373                                 driver_register(&gameport_drv->driver);
374                                 break;
375
376                         default:
377                                 break;
378                 }
379
380                 gameport_remove_duplicate_events(event);
381                 gameport_free_event(event);
382         }
383
384         mutex_unlock(&gameport_mutex);
385 }
386
387 /*
388  * Remove all events that have been submitted for a given gameport port.
389  */
390 static void gameport_remove_pending_events(struct gameport *gameport)
391 {
392         struct list_head *node, *next;
393         struct gameport_event *event;
394         unsigned long flags;
395
396         spin_lock_irqsave(&gameport_event_lock, flags);
397
398         list_for_each_safe(node, next, &gameport_event_list) {
399                 event = list_entry(node, struct gameport_event, node);
400                 if (event->object == gameport) {
401                         list_del_init(node);
402                         gameport_free_event(event);
403                 }
404         }
405
406         spin_unlock_irqrestore(&gameport_event_lock, flags);
407 }
408
409 /*
410  * Destroy child gameport port (if any) that has not been fully registered yet.
411  *
412  * Note that we rely on the fact that port can have only one child and therefore
413  * only one child registration request can be pending. Additionally, children
414  * are registered by driver's connect() handler so there can't be a grandchild
415  * pending registration together with a child.
416  */
417 static struct gameport *gameport_get_pending_child(struct gameport *parent)
418 {
419         struct gameport_event *event;
420         struct gameport *gameport, *child = NULL;
421         unsigned long flags;
422
423         spin_lock_irqsave(&gameport_event_lock, flags);
424
425         list_for_each_entry(event, &gameport_event_list, node) {
426                 if (event->type == GAMEPORT_REGISTER_PORT) {
427                         gameport = event->object;
428                         if (gameport->parent == parent) {
429                                 child = gameport;
430                                 break;
431                         }
432                 }
433         }
434
435         spin_unlock_irqrestore(&gameport_event_lock, flags);
436         return child;
437 }
438
439 static int gameport_thread(void *nothing)
440 {
441         do {
442                 gameport_handle_event();
443                 wait_event_interruptible(gameport_wait,
444                         kthread_should_stop() || !list_empty(&gameport_event_list));
445                 try_to_freeze();
446         } while (!kthread_should_stop());
447
448         printk(KERN_DEBUG "gameport: kgameportd exiting\n");
449         return 0;
450 }
451
452
453 /*
454  * Gameport port operations
455  */
456
457 static ssize_t gameport_show_description(struct device *dev, struct device_attribute *attr, char *buf)
458 {
459         struct gameport *gameport = to_gameport_port(dev);
460         return sprintf(buf, "%s\n", gameport->name);
461 }
462
463 static ssize_t gameport_rebind_driver(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
464 {
465         struct gameport *gameport = to_gameport_port(dev);
466         struct device_driver *drv;
467         int retval;
468
469         retval = mutex_lock_interruptible(&gameport_mutex);
470         if (retval)
471                 return retval;
472
473         retval = count;
474         if (!strncmp(buf, "none", count)) {
475                 gameport_disconnect_port(gameport);
476         } else if (!strncmp(buf, "reconnect", count)) {
477                 gameport_reconnect_port(gameport);
478         } else if (!strncmp(buf, "rescan", count)) {
479                 gameport_disconnect_port(gameport);
480                 gameport_find_driver(gameport);
481         } else if ((drv = driver_find(buf, &gameport_bus)) != NULL) {
482                 gameport_disconnect_port(gameport);
483                 gameport_bind_driver(gameport, to_gameport_driver(drv));
484                 put_driver(drv);
485         } else {
486                 retval = -EINVAL;
487         }
488
489         mutex_unlock(&gameport_mutex);
490
491         return retval;
492 }
493
494 static struct device_attribute gameport_device_attrs[] = {
495         __ATTR(description, S_IRUGO, gameport_show_description, NULL),
496         __ATTR(drvctl, S_IWUSR, NULL, gameport_rebind_driver),
497         __ATTR_NULL
498 };
499
500 static void gameport_release_port(struct device *dev)
501 {
502         struct gameport *gameport = to_gameport_port(dev);
503
504         kfree(gameport);
505         module_put(THIS_MODULE);
506 }
507
508 void gameport_set_phys(struct gameport *gameport, const char *fmt, ...)
509 {
510         va_list args;
511
512         va_start(args, fmt);
513         vsnprintf(gameport->phys, sizeof(gameport->phys), fmt, args);
514         va_end(args);
515 }
516
517 /*
518  * Prepare gameport port for registration.
519  */
520 static void gameport_init_port(struct gameport *gameport)
521 {
522         static atomic_t gameport_no = ATOMIC_INIT(0);
523
524         __module_get(THIS_MODULE);
525
526         mutex_init(&gameport->drv_mutex);
527         device_initialize(&gameport->dev);
528         snprintf(gameport->dev.bus_id, sizeof(gameport->dev.bus_id),
529                  "gameport%lu", (unsigned long)atomic_inc_return(&gameport_no) - 1);
530         gameport->dev.bus = &gameport_bus;
531         gameport->dev.release = gameport_release_port;
532         if (gameport->parent)
533                 gameport->dev.parent = &gameport->parent->dev;
534
535         spin_lock_init(&gameport->timer_lock);
536         init_timer(&gameport->poll_timer);
537         gameport->poll_timer.function = gameport_run_poll_handler;
538         gameport->poll_timer.data = (unsigned long)gameport;
539 }
540
541 /*
542  * Complete gameport port registration.
543  * Driver core will attempt to find appropriate driver for the port.
544  */
545 static void gameport_add_port(struct gameport *gameport)
546 {
547         if (gameport->parent)
548                 gameport->parent->child = gameport;
549
550         gameport->speed = gameport_measure_speed(gameport);
551
552         list_add_tail(&gameport->node, &gameport_list);
553
554         if (gameport->io)
555                 printk(KERN_INFO "gameport: %s is %s, io %#x, speed %dkHz\n",
556                         gameport->name, gameport->phys, gameport->io, gameport->speed);
557         else
558                 printk(KERN_INFO "gameport: %s is %s, speed %dkHz\n",
559                         gameport->name, gameport->phys, gameport->speed);
560
561         device_add(&gameport->dev);
562         gameport->registered = 1;
563 }
564
565 /*
566  * gameport_destroy_port() completes deregistration process and removes
567  * port from the system
568  */
569 static void gameport_destroy_port(struct gameport *gameport)
570 {
571         struct gameport *child;
572
573         child = gameport_get_pending_child(gameport);
574         if (child) {
575                 gameport_remove_pending_events(child);
576                 put_device(&child->dev);
577         }
578
579         if (gameport->parent) {
580                 gameport->parent->child = NULL;
581                 gameport->parent = NULL;
582         }
583
584         if (gameport->registered) {
585                 device_del(&gameport->dev);
586                 list_del_init(&gameport->node);
587                 gameport->registered = 0;
588         }
589
590         gameport_remove_pending_events(gameport);
591         put_device(&gameport->dev);
592 }
593
594 /*
595  * Reconnect gameport port and all its children (re-initialize attached devices)
596  */
597 static void gameport_reconnect_port(struct gameport *gameport)
598 {
599         do {
600                 if (!gameport->drv || !gameport->drv->reconnect || gameport->drv->reconnect(gameport)) {
601                         gameport_disconnect_port(gameport);
602                         gameport_find_driver(gameport);
603                         /* Ok, old children are now gone, we are done */
604                         break;
605                 }
606                 gameport = gameport->child;
607         } while (gameport);
608 }
609
610 /*
611  * gameport_disconnect_port() unbinds a port from its driver. As a side effect
612  * all child ports are unbound and destroyed.
613  */
614 static void gameport_disconnect_port(struct gameport *gameport)
615 {
616         struct gameport *s, *parent;
617
618         if (gameport->child) {
619                 /*
620                  * Children ports should be disconnected and destroyed
621                  * first, staring with the leaf one, since we don't want
622                  * to do recursion
623                  */
624                 for (s = gameport; s->child; s = s->child)
625                         /* empty */;
626
627                 do {
628                         parent = s->parent;
629
630                         gameport_release_driver(s);
631                         gameport_destroy_port(s);
632                 } while ((s = parent) != gameport);
633         }
634
635         /*
636          * Ok, no children left, now disconnect this port
637          */
638         gameport_release_driver(gameport);
639 }
640
641 void gameport_rescan(struct gameport *gameport)
642 {
643         gameport_queue_event(gameport, NULL, GAMEPORT_RESCAN);
644 }
645
646 void gameport_reconnect(struct gameport *gameport)
647 {
648         gameport_queue_event(gameport, NULL, GAMEPORT_RECONNECT);
649 }
650
651 /*
652  * Submits register request to kgameportd for subsequent execution.
653  * Note that port registration is always asynchronous.
654  */
655 void __gameport_register_port(struct gameport *gameport, struct module *owner)
656 {
657         gameport_init_port(gameport);
658         gameport_queue_event(gameport, owner, GAMEPORT_REGISTER_PORT);
659 }
660
661 /*
662  * Synchronously unregisters gameport port.
663  */
664 void gameport_unregister_port(struct gameport *gameport)
665 {
666         mutex_lock(&gameport_mutex);
667         gameport_disconnect_port(gameport);
668         gameport_destroy_port(gameport);
669         mutex_unlock(&gameport_mutex);
670 }
671
672
673 /*
674  * Gameport driver operations
675  */
676
677 static ssize_t gameport_driver_show_description(struct device_driver *drv, char *buf)
678 {
679         struct gameport_driver *driver = to_gameport_driver(drv);
680         return sprintf(buf, "%s\n", driver->description ? driver->description : "(none)");
681 }
682
683 static struct driver_attribute gameport_driver_attrs[] = {
684         __ATTR(description, S_IRUGO, gameport_driver_show_description, NULL),
685         __ATTR_NULL
686 };
687
688 static int gameport_driver_probe(struct device *dev)
689 {
690         struct gameport *gameport = to_gameport_port(dev);
691         struct gameport_driver *drv = to_gameport_driver(dev->driver);
692
693         drv->connect(gameport, drv);
694         return gameport->drv ? 0 : -ENODEV;
695 }
696
697 static int gameport_driver_remove(struct device *dev)
698 {
699         struct gameport *gameport = to_gameport_port(dev);
700         struct gameport_driver *drv = to_gameport_driver(dev->driver);
701
702         drv->disconnect(gameport);
703         return 0;
704 }
705
706 static struct bus_type gameport_bus = {
707         .name = "gameport",
708         .probe = gameport_driver_probe,
709         .remove = gameport_driver_remove,
710 };
711
712 void __gameport_register_driver(struct gameport_driver *drv, struct module *owner)
713 {
714         drv->driver.bus = &gameport_bus;
715         gameport_queue_event(drv, owner, GAMEPORT_REGISTER_DRIVER);
716 }
717
718 void gameport_unregister_driver(struct gameport_driver *drv)
719 {
720         struct gameport *gameport;
721
722         mutex_lock(&gameport_mutex);
723         drv->ignore = 1;        /* so gameport_find_driver ignores it */
724
725 start_over:
726         list_for_each_entry(gameport, &gameport_list, node) {
727                 if (gameport->drv == drv) {
728                         gameport_disconnect_port(gameport);
729                         gameport_find_driver(gameport);
730                         /* we could've deleted some ports, restart */
731                         goto start_over;
732                 }
733         }
734
735         driver_unregister(&drv->driver);
736         mutex_unlock(&gameport_mutex);
737 }
738
739 static int gameport_bus_match(struct device *dev, struct device_driver *drv)
740 {
741         struct gameport_driver *gameport_drv = to_gameport_driver(drv);
742
743         return !gameport_drv->ignore;
744 }
745
746 static void gameport_set_drv(struct gameport *gameport, struct gameport_driver *drv)
747 {
748         mutex_lock(&gameport->drv_mutex);
749         gameport->drv = drv;
750         mutex_unlock(&gameport->drv_mutex);
751 }
752
753 int gameport_open(struct gameport *gameport, struct gameport_driver *drv, int mode)
754 {
755
756         if (gameport->open) {
757                 if (gameport->open(gameport, mode)) {
758                         return -1;
759                 }
760         } else {
761                 if (mode != GAMEPORT_MODE_RAW)
762                         return -1;
763         }
764
765         gameport_set_drv(gameport, drv);
766         return 0;
767 }
768
769 void gameport_close(struct gameport *gameport)
770 {
771         del_timer_sync(&gameport->poll_timer);
772         gameport->poll_handler = NULL;
773         gameport->poll_interval = 0;
774         gameport_set_drv(gameport, NULL);
775         if (gameport->close)
776                 gameport->close(gameport);
777 }
778
779 static int __init gameport_init(void)
780 {
781         gameport_task = kthread_run(gameport_thread, NULL, "kgameportd");
782         if (IS_ERR(gameport_task)) {
783                 printk(KERN_ERR "gameport: Failed to start kgameportd\n");
784                 return PTR_ERR(gameport_task);
785         }
786
787         gameport_bus.dev_attrs = gameport_device_attrs;
788         gameport_bus.drv_attrs = gameport_driver_attrs;
789         gameport_bus.match = gameport_bus_match;
790         bus_register(&gameport_bus);
791
792         return 0;
793 }
794
795 static void __exit gameport_exit(void)
796 {
797         bus_unregister(&gameport_bus);
798         kthread_stop(gameport_task);
799 }
800
801 subsys_initcall(gameport_init);
802 module_exit(gameport_exit);