Merge master.kernel.org:/home/rmk/linux-2.6-serial
[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
26 /*#include <asm/io.h>*/
27
28 MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
29 MODULE_DESCRIPTION("Generic gameport layer");
30 MODULE_LICENSE("GPL");
31
32 EXPORT_SYMBOL(__gameport_register_port);
33 EXPORT_SYMBOL(gameport_unregister_port);
34 EXPORT_SYMBOL(__gameport_register_driver);
35 EXPORT_SYMBOL(gameport_unregister_driver);
36 EXPORT_SYMBOL(gameport_open);
37 EXPORT_SYMBOL(gameport_close);
38 EXPORT_SYMBOL(gameport_rescan);
39 EXPORT_SYMBOL(gameport_cooked_read);
40 EXPORT_SYMBOL(gameport_set_name);
41 EXPORT_SYMBOL(gameport_set_phys);
42 EXPORT_SYMBOL(gameport_start_polling);
43 EXPORT_SYMBOL(gameport_stop_polling);
44
45 /*
46  * gameport_sem protects entire gameport subsystem and is taken
47  * every time gameport port or driver registrered or unregistered.
48  */
49 static DECLARE_MUTEX(gameport_sem);
50
51 static LIST_HEAD(gameport_list);
52
53 static struct bus_type gameport_bus;
54
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 * (unsigned long)HZ / (1000 / 50)) / (tx < 1 ? 1 : tx);
137
138 #else
139
140         unsigned int j, t = 0;
141
142         if (gameport_open(gameport, NULL, GAMEPORT_MODE_RAW))
143                 return 0;
144
145         j = jiffies; while (j == jiffies);
146         j = jiffies; while (j == jiffies) { t++; gameport_read(gameport); }
147
148         gameport_close(gameport);
149         return t * HZ / 1000;
150
151 #endif
152 }
153
154 void gameport_start_polling(struct gameport *gameport)
155 {
156         spin_lock(&gameport->timer_lock);
157
158         if (!gameport->poll_cnt++) {
159                 BUG_ON(!gameport->poll_handler);
160                 BUG_ON(!gameport->poll_interval);
161                 mod_timer(&gameport->poll_timer, jiffies + msecs_to_jiffies(gameport->poll_interval));
162         }
163
164         spin_unlock(&gameport->timer_lock);
165 }
166
167 void gameport_stop_polling(struct gameport *gameport)
168 {
169         spin_lock(&gameport->timer_lock);
170
171         if (!--gameport->poll_cnt)
172                 del_timer(&gameport->poll_timer);
173
174         spin_unlock(&gameport->timer_lock);
175 }
176
177 static void gameport_run_poll_handler(unsigned long d)
178 {
179         struct gameport *gameport = (struct gameport *)d;
180
181         gameport->poll_handler(gameport);
182         if (gameport->poll_cnt)
183                 mod_timer(&gameport->poll_timer, jiffies + msecs_to_jiffies(gameport->poll_interval));
184 }
185
186 /*
187  * Basic gameport -> driver core mappings
188  */
189
190 static void gameport_bind_driver(struct gameport *gameport, struct gameport_driver *drv)
191 {
192         down_write(&gameport_bus.subsys.rwsem);
193
194         gameport->dev.driver = &drv->driver;
195         if (drv->connect(gameport, drv)) {
196                 gameport->dev.driver = NULL;
197                 goto out;
198         }
199         device_bind_driver(&gameport->dev);
200 out:
201         up_write(&gameport_bus.subsys.rwsem);
202 }
203
204 static void gameport_release_driver(struct gameport *gameport)
205 {
206         down_write(&gameport_bus.subsys.rwsem);
207         device_release_driver(&gameport->dev);
208         up_write(&gameport_bus.subsys.rwsem);
209 }
210
211 static void gameport_find_driver(struct gameport *gameport)
212 {
213         down_write(&gameport_bus.subsys.rwsem);
214         device_attach(&gameport->dev);
215         up_write(&gameport_bus.subsys.rwsem);
216 }
217
218
219 /*
220  * Gameport event processing.
221  */
222
223 enum gameport_event_type {
224         GAMEPORT_RESCAN,
225         GAMEPORT_RECONNECT,
226         GAMEPORT_REGISTER_PORT,
227         GAMEPORT_REGISTER_DRIVER,
228 };
229
230 struct gameport_event {
231         enum gameport_event_type type;
232         void *object;
233         struct module *owner;
234         struct list_head node;
235 };
236
237 static DEFINE_SPINLOCK(gameport_event_lock);    /* protects gameport_event_list */
238 static LIST_HEAD(gameport_event_list);
239 static DECLARE_WAIT_QUEUE_HEAD(gameport_wait);
240 static struct task_struct *gameport_task;
241
242 static void gameport_queue_event(void *object, struct module *owner,
243                               enum gameport_event_type event_type)
244 {
245         unsigned long flags;
246         struct gameport_event *event;
247
248         spin_lock_irqsave(&gameport_event_lock, flags);
249
250         /*
251          * Scan event list for the other events for the same gameport port,
252          * starting with the most recent one. If event is the same we
253          * do not need add new one. If event is of different type we
254          * need to add this event and should not look further because
255          * we need to preseve sequence of distinct events.
256          */
257         list_for_each_entry_reverse(event, &gameport_event_list, node) {
258                 if (event->object == object) {
259                         if (event->type == event_type)
260                                 goto out;
261                         break;
262                 }
263         }
264
265         if ((event = kmalloc(sizeof(struct gameport_event), GFP_ATOMIC))) {
266                 if (!try_module_get(owner)) {
267                         printk(KERN_WARNING "gameport: Can't get module reference, dropping event %d\n", event_type);
268                         goto out;
269                 }
270
271                 event->type = event_type;
272                 event->object = object;
273                 event->owner = owner;
274
275                 list_add_tail(&event->node, &gameport_event_list);
276                 wake_up(&gameport_wait);
277         } else {
278                 printk(KERN_ERR "gameport: Not enough memory to queue event %d\n", event_type);
279         }
280 out:
281         spin_unlock_irqrestore(&gameport_event_lock, flags);
282 }
283
284 static void gameport_free_event(struct gameport_event *event)
285 {
286         module_put(event->owner);
287         kfree(event);
288 }
289
290 static void gameport_remove_duplicate_events(struct gameport_event *event)
291 {
292         struct list_head *node, *next;
293         struct gameport_event *e;
294         unsigned long flags;
295
296         spin_lock_irqsave(&gameport_event_lock, flags);
297
298         list_for_each_safe(node, next, &gameport_event_list) {
299                 e = list_entry(node, struct gameport_event, node);
300                 if (event->object == e->object) {
301                         /*
302                          * If this event is of different type we should not
303                          * look further - we only suppress duplicate events
304                          * that were sent back-to-back.
305                          */
306                         if (event->type != e->type)
307                                 break;
308
309                         list_del_init(node);
310                         gameport_free_event(e);
311                 }
312         }
313
314         spin_unlock_irqrestore(&gameport_event_lock, flags);
315 }
316
317
318 static struct gameport_event *gameport_get_event(void)
319 {
320         struct gameport_event *event;
321         struct list_head *node;
322         unsigned long flags;
323
324         spin_lock_irqsave(&gameport_event_lock, flags);
325
326         if (list_empty(&gameport_event_list)) {
327                 spin_unlock_irqrestore(&gameport_event_lock, flags);
328                 return NULL;
329         }
330
331         node = gameport_event_list.next;
332         event = list_entry(node, struct gameport_event, node);
333         list_del_init(node);
334
335         spin_unlock_irqrestore(&gameport_event_lock, flags);
336
337         return event;
338 }
339
340 static void gameport_handle_event(void)
341 {
342         struct gameport_event *event;
343         struct gameport_driver *gameport_drv;
344
345         down(&gameport_sem);
346
347         /*
348          * Note that we handle only one event here to give swsusp
349          * a chance to freeze kgameportd thread. Gameport events
350          * should be pretty rare so we are not concerned about
351          * taking performance hit.
352          */
353         if ((event = gameport_get_event())) {
354
355                 switch (event->type) {
356                         case GAMEPORT_REGISTER_PORT:
357                                 gameport_add_port(event->object);
358                                 break;
359
360                         case GAMEPORT_RECONNECT:
361                                 gameport_reconnect_port(event->object);
362                                 break;
363
364                         case GAMEPORT_RESCAN:
365                                 gameport_disconnect_port(event->object);
366                                 gameport_find_driver(event->object);
367                                 break;
368
369                         case GAMEPORT_REGISTER_DRIVER:
370                                 gameport_drv = event->object;
371                                 driver_register(&gameport_drv->driver);
372                                 break;
373
374                         default:
375                                 break;
376                 }
377
378                 gameport_remove_duplicate_events(event);
379                 gameport_free_event(event);
380         }
381
382         up(&gameport_sem);
383 }
384
385 /*
386  * Remove all events that have been submitted for a given gameport port.
387  */
388 static void gameport_remove_pending_events(struct gameport *gameport)
389 {
390         struct list_head *node, *next;
391         struct gameport_event *event;
392         unsigned long flags;
393
394         spin_lock_irqsave(&gameport_event_lock, flags);
395
396         list_for_each_safe(node, next, &gameport_event_list) {
397                 event = list_entry(node, struct gameport_event, node);
398                 if (event->object == gameport) {
399                         list_del_init(node);
400                         gameport_free_event(event);
401                 }
402         }
403
404         spin_unlock_irqrestore(&gameport_event_lock, flags);
405 }
406
407 /*
408  * Destroy child gameport port (if any) that has not been fully registered yet.
409  *
410  * Note that we rely on the fact that port can have only one child and therefore
411  * only one child registration request can be pending. Additionally, children
412  * are registered by driver's connect() handler so there can't be a grandchild
413  * pending registration together with a child.
414  */
415 static struct gameport *gameport_get_pending_child(struct gameport *parent)
416 {
417         struct gameport_event *event;
418         struct gameport *gameport, *child = NULL;
419         unsigned long flags;
420
421         spin_lock_irqsave(&gameport_event_lock, flags);
422
423         list_for_each_entry(event, &gameport_event_list, node) {
424                 if (event->type == GAMEPORT_REGISTER_PORT) {
425                         gameport = event->object;
426                         if (gameport->parent == parent) {
427                                 child = gameport;
428                                 break;
429                         }
430                 }
431         }
432
433         spin_unlock_irqrestore(&gameport_event_lock, flags);
434         return child;
435 }
436
437 static int gameport_thread(void *nothing)
438 {
439         do {
440                 gameport_handle_event();
441                 wait_event_interruptible(gameport_wait,
442                         kthread_should_stop() || !list_empty(&gameport_event_list));
443                 try_to_freeze();
444         } while (!kthread_should_stop());
445
446         printk(KERN_DEBUG "gameport: kgameportd exiting\n");
447         return 0;
448 }
449
450
451 /*
452  * Gameport port operations
453  */
454
455 static ssize_t gameport_show_description(struct device *dev, struct device_attribute *attr, char *buf)
456 {
457         struct gameport *gameport = to_gameport_port(dev);
458         return sprintf(buf, "%s\n", gameport->name);
459 }
460
461 static ssize_t gameport_rebind_driver(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
462 {
463         struct gameport *gameport = to_gameport_port(dev);
464         struct device_driver *drv;
465         int retval;
466
467         retval = down_interruptible(&gameport_sem);
468         if (retval)
469                 return retval;
470
471         retval = count;
472         if (!strncmp(buf, "none", count)) {
473                 gameport_disconnect_port(gameport);
474         } else if (!strncmp(buf, "reconnect", count)) {
475                 gameport_reconnect_port(gameport);
476         } else if (!strncmp(buf, "rescan", count)) {
477                 gameport_disconnect_port(gameport);
478                 gameport_find_driver(gameport);
479         } else if ((drv = driver_find(buf, &gameport_bus)) != NULL) {
480                 gameport_disconnect_port(gameport);
481                 gameport_bind_driver(gameport, to_gameport_driver(drv));
482                 put_driver(drv);
483         } else {
484                 retval = -EINVAL;
485         }
486
487         up(&gameport_sem);
488
489         return retval;
490 }
491
492 static struct device_attribute gameport_device_attrs[] = {
493         __ATTR(description, S_IRUGO, gameport_show_description, NULL),
494         __ATTR(drvctl, S_IWUSR, NULL, gameport_rebind_driver),
495         __ATTR_NULL
496 };
497
498 static void gameport_release_port(struct device *dev)
499 {
500         struct gameport *gameport = to_gameport_port(dev);
501
502         kfree(gameport);
503         module_put(THIS_MODULE);
504 }
505
506 void gameport_set_phys(struct gameport *gameport, const char *fmt, ...)
507 {
508         va_list args;
509
510         va_start(args, fmt);
511         vsnprintf(gameport->phys, sizeof(gameport->phys), fmt, args);
512         va_end(args);
513 }
514
515 /*
516  * Prepare gameport port for registration.
517  */
518 static void gameport_init_port(struct gameport *gameport)
519 {
520         static atomic_t gameport_no = ATOMIC_INIT(0);
521
522         __module_get(THIS_MODULE);
523
524         init_MUTEX(&gameport->drv_sem);
525         device_initialize(&gameport->dev);
526         snprintf(gameport->dev.bus_id, sizeof(gameport->dev.bus_id),
527                  "gameport%lu", (unsigned long)atomic_inc_return(&gameport_no) - 1);
528         gameport->dev.bus = &gameport_bus;
529         gameport->dev.release = gameport_release_port;
530         if (gameport->parent)
531                 gameport->dev.parent = &gameport->parent->dev;
532
533         spin_lock_init(&gameport->timer_lock);
534         init_timer(&gameport->poll_timer);
535         gameport->poll_timer.function = gameport_run_poll_handler;
536         gameport->poll_timer.data = (unsigned long)gameport;
537 }
538
539 /*
540  * Complete gameport port registration.
541  * Driver core will attempt to find appropriate driver for the port.
542  */
543 static void gameport_add_port(struct gameport *gameport)
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         device_add(&gameport->dev);
560         gameport->registered = 1;
561 }
562
563 /*
564  * gameport_destroy_port() completes deregistration process and removes
565  * port from the system
566  */
567 static void gameport_destroy_port(struct gameport *gameport)
568 {
569         struct gameport *child;
570
571         child = gameport_get_pending_child(gameport);
572         if (child) {
573                 gameport_remove_pending_events(child);
574                 put_device(&child->dev);
575         }
576
577         if (gameport->parent) {
578                 gameport->parent->child = NULL;
579                 gameport->parent = NULL;
580         }
581
582         if (gameport->registered) {
583                 device_del(&gameport->dev);
584                 list_del_init(&gameport->node);
585                 gameport->registered = 0;
586         }
587
588         gameport_remove_pending_events(gameport);
589         put_device(&gameport->dev);
590 }
591
592 /*
593  * Reconnect gameport port and all its children (re-initialize attached devices)
594  */
595 static void gameport_reconnect_port(struct gameport *gameport)
596 {
597         do {
598                 if (!gameport->drv || !gameport->drv->reconnect || gameport->drv->reconnect(gameport)) {
599                         gameport_disconnect_port(gameport);
600                         gameport_find_driver(gameport);
601                         /* Ok, old children are now gone, we are done */
602                         break;
603                 }
604                 gameport = gameport->child;
605         } while (gameport);
606 }
607
608 /*
609  * gameport_disconnect_port() unbinds a port from its driver. As a side effect
610  * all child ports are unbound and destroyed.
611  */
612 static void gameport_disconnect_port(struct gameport *gameport)
613 {
614         struct gameport *s, *parent;
615
616         if (gameport->child) {
617                 /*
618                  * Children ports should be disconnected and destroyed
619                  * first, staring with the leaf one, since we don't want
620                  * to do recursion
621                  */
622                 for (s = gameport; s->child; s = s->child)
623                         /* empty */;
624
625                 do {
626                         parent = s->parent;
627
628                         gameport_release_driver(s);
629                         gameport_destroy_port(s);
630                 } while ((s = parent) != gameport);
631         }
632
633         /*
634          * Ok, no children left, now disconnect this port
635          */
636         gameport_release_driver(gameport);
637 }
638
639 void gameport_rescan(struct gameport *gameport)
640 {
641         gameport_queue_event(gameport, NULL, GAMEPORT_RESCAN);
642 }
643
644 void gameport_reconnect(struct gameport *gameport)
645 {
646         gameport_queue_event(gameport, NULL, GAMEPORT_RECONNECT);
647 }
648
649 /*
650  * Submits register request to kgameportd for subsequent execution.
651  * Note that port registration is always asynchronous.
652  */
653 void __gameport_register_port(struct gameport *gameport, struct module *owner)
654 {
655         gameport_init_port(gameport);
656         gameport_queue_event(gameport, owner, GAMEPORT_REGISTER_PORT);
657 }
658
659 /*
660  * Synchronously unregisters gameport port.
661  */
662 void gameport_unregister_port(struct gameport *gameport)
663 {
664         down(&gameport_sem);
665         gameport_disconnect_port(gameport);
666         gameport_destroy_port(gameport);
667         up(&gameport_sem);
668 }
669
670
671 /*
672  * Gameport driver operations
673  */
674
675 static ssize_t gameport_driver_show_description(struct device_driver *drv, char *buf)
676 {
677         struct gameport_driver *driver = to_gameport_driver(drv);
678         return sprintf(buf, "%s\n", driver->description ? driver->description : "(none)");
679 }
680
681 static struct driver_attribute gameport_driver_attrs[] = {
682         __ATTR(description, S_IRUGO, gameport_driver_show_description, NULL),
683         __ATTR_NULL
684 };
685
686 static int gameport_driver_probe(struct device *dev)
687 {
688         struct gameport *gameport = to_gameport_port(dev);
689         struct gameport_driver *drv = to_gameport_driver(dev->driver);
690
691         drv->connect(gameport, drv);
692         return gameport->drv ? 0 : -ENODEV;
693 }
694
695 static int gameport_driver_remove(struct device *dev)
696 {
697         struct gameport *gameport = to_gameport_port(dev);
698         struct gameport_driver *drv = to_gameport_driver(dev->driver);
699
700         drv->disconnect(gameport);
701         return 0;
702 }
703
704 static struct bus_type gameport_bus = {
705         .name = "gameport",
706         .probe = gameport_driver_probe,
707         .remove = gameport_driver_remove,
708 };
709
710 void __gameport_register_driver(struct gameport_driver *drv, struct module *owner)
711 {
712         drv->driver.bus = &gameport_bus;
713         gameport_queue_event(drv, owner, GAMEPORT_REGISTER_DRIVER);
714 }
715
716 void gameport_unregister_driver(struct gameport_driver *drv)
717 {
718         struct gameport *gameport;
719
720         down(&gameport_sem);
721         drv->ignore = 1;        /* so gameport_find_driver ignores it */
722
723 start_over:
724         list_for_each_entry(gameport, &gameport_list, node) {
725                 if (gameport->drv == drv) {
726                         gameport_disconnect_port(gameport);
727                         gameport_find_driver(gameport);
728                         /* we could've deleted some ports, restart */
729                         goto start_over;
730                 }
731         }
732
733         driver_unregister(&drv->driver);
734         up(&gameport_sem);
735 }
736
737 static int gameport_bus_match(struct device *dev, struct device_driver *drv)
738 {
739         struct gameport_driver *gameport_drv = to_gameport_driver(drv);
740
741         return !gameport_drv->ignore;
742 }
743
744 static void gameport_set_drv(struct gameport *gameport, struct gameport_driver *drv)
745 {
746         down(&gameport->drv_sem);
747         gameport->drv = drv;
748         up(&gameport->drv_sem);
749 }
750
751 int gameport_open(struct gameport *gameport, struct gameport_driver *drv, int mode)
752 {
753
754         if (gameport->open) {
755                 if (gameport->open(gameport, mode)) {
756                         return -1;
757                 }
758         } else {
759                 if (mode != GAMEPORT_MODE_RAW)
760                         return -1;
761         }
762
763         gameport_set_drv(gameport, drv);
764         return 0;
765 }
766
767 void gameport_close(struct gameport *gameport)
768 {
769         del_timer_sync(&gameport->poll_timer);
770         gameport->poll_handler = NULL;
771         gameport->poll_interval = 0;
772         gameport_set_drv(gameport, NULL);
773         if (gameport->close)
774                 gameport->close(gameport);
775 }
776
777 static int __init gameport_init(void)
778 {
779         gameport_task = kthread_run(gameport_thread, NULL, "kgameportd");
780         if (IS_ERR(gameport_task)) {
781                 printk(KERN_ERR "gameport: Failed to start kgameportd\n");
782                 return PTR_ERR(gameport_task);
783         }
784
785         gameport_bus.dev_attrs = gameport_device_attrs;
786         gameport_bus.drv_attrs = gameport_driver_attrs;
787         gameport_bus.match = gameport_bus_match;
788         bus_register(&gameport_bus);
789
790         return 0;
791 }
792
793 static void __exit gameport_exit(void)
794 {
795         bus_unregister(&gameport_bus);
796         kthread_stop(gameport_task);
797 }
798
799 module_init(gameport_init);
800 module_exit(gameport_exit);