i8253: Create linux/i8253.h and use it in all 8253 related files
[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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15
16 #include <linux/stddef.h>
17 #include <linux/module.h>
18 #include <linux/ioport.h>
19 #include <linux/init.h>
20 #include <linux/gameport.h>
21 #include <linux/slab.h>
22 #include <linux/delay.h>
23 #include <linux/workqueue.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 /*
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 <linux/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         raw_spin_lock_irqsave(&i8253_lock, flags);
61         outb_p(0x00, 0x43);
62         count = inb_p(0x40);
63         count |= inb_p(0x40) << 8;
64         raw_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 (this_cpu_read(cpu_info.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                 dev_warn(&gameport->dev,
194                          "device_bind_driver() failed for %s (%s) and %s, error: %d\n",
195                         gameport->phys, gameport->name,
196                         drv->description, error);
197                 drv->disconnect(gameport);
198                 gameport->dev.driver = NULL;
199                 return error;
200         }
201
202         return 0;
203 }
204
205 static void gameport_find_driver(struct gameport *gameport)
206 {
207         int error;
208
209         error = device_attach(&gameport->dev);
210         if (error < 0)
211                 dev_warn(&gameport->dev,
212                          "device_attach() failed for %s (%s), error: %d\n",
213                          gameport->phys, gameport->name, error);
214 }
215
216
217 /*
218  * Gameport event processing.
219  */
220
221 enum gameport_event_type {
222         GAMEPORT_REGISTER_PORT,
223         GAMEPORT_ATTACH_DRIVER,
224 };
225
226 struct gameport_event {
227         enum gameport_event_type type;
228         void *object;
229         struct module *owner;
230         struct list_head node;
231 };
232
233 static DEFINE_SPINLOCK(gameport_event_lock);    /* protects gameport_event_list */
234 static LIST_HEAD(gameport_event_list);
235
236 static struct gameport_event *gameport_get_event(void)
237 {
238         struct gameport_event *event = NULL;
239         unsigned long flags;
240
241         spin_lock_irqsave(&gameport_event_lock, flags);
242
243         if (!list_empty(&gameport_event_list)) {
244                 event = list_first_entry(&gameport_event_list,
245                                          struct gameport_event, node);
246                 list_del_init(&event->node);
247         }
248
249         spin_unlock_irqrestore(&gameport_event_lock, flags);
250         return event;
251 }
252
253 static void gameport_free_event(struct gameport_event *event)
254 {
255         module_put(event->owner);
256         kfree(event);
257 }
258
259 static void gameport_remove_duplicate_events(struct gameport_event *event)
260 {
261         struct gameport_event *e, *next;
262         unsigned long flags;
263
264         spin_lock_irqsave(&gameport_event_lock, flags);
265
266         list_for_each_entry_safe(e, next, &gameport_event_list, node) {
267                 if (event->object == e->object) {
268                         /*
269                          * If this event is of different type we should not
270                          * look further - we only suppress duplicate events
271                          * that were sent back-to-back.
272                          */
273                         if (event->type != e->type)
274                                 break;
275
276                         list_del_init(&e->node);
277                         gameport_free_event(e);
278                 }
279         }
280
281         spin_unlock_irqrestore(&gameport_event_lock, flags);
282 }
283
284
285 static void gameport_handle_events(struct work_struct *work)
286 {
287         struct gameport_event *event;
288
289         mutex_lock(&gameport_mutex);
290
291         /*
292          * Note that we handle only one event here to give swsusp
293          * a chance to freeze kgameportd thread. Gameport events
294          * should be pretty rare so we are not concerned about
295          * taking performance hit.
296          */
297         if ((event = gameport_get_event())) {
298
299                 switch (event->type) {
300
301                 case GAMEPORT_REGISTER_PORT:
302                         gameport_add_port(event->object);
303                         break;
304
305                 case GAMEPORT_ATTACH_DRIVER:
306                         gameport_attach_driver(event->object);
307                         break;
308                 }
309
310                 gameport_remove_duplicate_events(event);
311                 gameport_free_event(event);
312         }
313
314         mutex_unlock(&gameport_mutex);
315 }
316
317 static DECLARE_WORK(gameport_event_work, gameport_handle_events);
318
319 static int gameport_queue_event(void *object, struct module *owner,
320                                 enum gameport_event_type event_type)
321 {
322         unsigned long flags;
323         struct gameport_event *event;
324         int retval = 0;
325
326         spin_lock_irqsave(&gameport_event_lock, flags);
327
328         /*
329          * Scan event list for the other events for the same gameport port,
330          * starting with the most recent one. If event is the same we
331          * do not need add new one. If event is of different type we
332          * need to add this event and should not look further because
333          * we need to preserve sequence of distinct events.
334          */
335         list_for_each_entry_reverse(event, &gameport_event_list, node) {
336                 if (event->object == object) {
337                         if (event->type == event_type)
338                                 goto out;
339                         break;
340                 }
341         }
342
343         event = kmalloc(sizeof(struct gameport_event), GFP_ATOMIC);
344         if (!event) {
345                 pr_err("Not enough memory to queue event %d\n", event_type);
346                 retval = -ENOMEM;
347                 goto out;
348         }
349
350         if (!try_module_get(owner)) {
351                 pr_warning("Can't get module reference, dropping event %d\n",
352                            event_type);
353                 kfree(event);
354                 retval = -EINVAL;
355                 goto out;
356         }
357
358         event->type = event_type;
359         event->object = object;
360         event->owner = owner;
361
362         list_add_tail(&event->node, &gameport_event_list);
363         queue_work(system_long_wq, &gameport_event_work);
364
365 out:
366         spin_unlock_irqrestore(&gameport_event_lock, flags);
367         return retval;
368 }
369
370 /*
371  * Remove all events that have been submitted for a given object,
372  * be it a gameport port or a driver.
373  */
374 static void gameport_remove_pending_events(void *object)
375 {
376         struct gameport_event *event, *next;
377         unsigned long flags;
378
379         spin_lock_irqsave(&gameport_event_lock, flags);
380
381         list_for_each_entry_safe(event, next, &gameport_event_list, node) {
382                 if (event->object == object) {
383                         list_del_init(&event->node);
384                         gameport_free_event(event);
385                 }
386         }
387
388         spin_unlock_irqrestore(&gameport_event_lock, flags);
389 }
390
391 /*
392  * Destroy child gameport port (if any) that has not been fully registered yet.
393  *
394  * Note that we rely on the fact that port can have only one child and therefore
395  * only one child registration request can be pending. Additionally, children
396  * are registered by driver's connect() handler so there can't be a grandchild
397  * pending registration together with a child.
398  */
399 static struct gameport *gameport_get_pending_child(struct gameport *parent)
400 {
401         struct gameport_event *event;
402         struct gameport *gameport, *child = NULL;
403         unsigned long flags;
404
405         spin_lock_irqsave(&gameport_event_lock, flags);
406
407         list_for_each_entry(event, &gameport_event_list, node) {
408                 if (event->type == GAMEPORT_REGISTER_PORT) {
409                         gameport = event->object;
410                         if (gameport->parent == parent) {
411                                 child = gameport;
412                                 break;
413                         }
414                 }
415         }
416
417         spin_unlock_irqrestore(&gameport_event_lock, flags);
418         return child;
419 }
420
421 /*
422  * Gameport port operations
423  */
424
425 static ssize_t gameport_show_description(struct device *dev, struct device_attribute *attr, char *buf)
426 {
427         struct gameport *gameport = to_gameport_port(dev);
428
429         return sprintf(buf, "%s\n", gameport->name);
430 }
431
432 static ssize_t gameport_rebind_driver(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
433 {
434         struct gameport *gameport = to_gameport_port(dev);
435         struct device_driver *drv;
436         int error;
437
438         error = mutex_lock_interruptible(&gameport_mutex);
439         if (error)
440                 return error;
441
442         if (!strncmp(buf, "none", count)) {
443                 gameport_disconnect_port(gameport);
444         } else if (!strncmp(buf, "reconnect", count)) {
445                 gameport_reconnect_port(gameport);
446         } else if (!strncmp(buf, "rescan", count)) {
447                 gameport_disconnect_port(gameport);
448                 gameport_find_driver(gameport);
449         } else if ((drv = driver_find(buf, &gameport_bus)) != NULL) {
450                 gameport_disconnect_port(gameport);
451                 error = gameport_bind_driver(gameport, to_gameport_driver(drv));
452                 put_driver(drv);
453         } else {
454                 error = -EINVAL;
455         }
456
457         mutex_unlock(&gameport_mutex);
458
459         return error ? error : count;
460 }
461
462 static struct device_attribute gameport_device_attrs[] = {
463         __ATTR(description, S_IRUGO, gameport_show_description, NULL),
464         __ATTR(drvctl, S_IWUSR, NULL, gameport_rebind_driver),
465         __ATTR_NULL
466 };
467
468 static void gameport_release_port(struct device *dev)
469 {
470         struct gameport *gameport = to_gameport_port(dev);
471
472         kfree(gameport);
473         module_put(THIS_MODULE);
474 }
475
476 void gameport_set_phys(struct gameport *gameport, const char *fmt, ...)
477 {
478         va_list args;
479
480         va_start(args, fmt);
481         vsnprintf(gameport->phys, sizeof(gameport->phys), fmt, args);
482         va_end(args);
483 }
484 EXPORT_SYMBOL(gameport_set_phys);
485
486 /*
487  * Prepare gameport port for registration.
488  */
489 static void gameport_init_port(struct gameport *gameport)
490 {
491         static atomic_t gameport_no = ATOMIC_INIT(0);
492
493         __module_get(THIS_MODULE);
494
495         mutex_init(&gameport->drv_mutex);
496         device_initialize(&gameport->dev);
497         dev_set_name(&gameport->dev, "gameport%lu",
498                         (unsigned long)atomic_inc_return(&gameport_no) - 1);
499         gameport->dev.bus = &gameport_bus;
500         gameport->dev.release = gameport_release_port;
501         if (gameport->parent)
502                 gameport->dev.parent = &gameport->parent->dev;
503
504         INIT_LIST_HEAD(&gameport->node);
505         spin_lock_init(&gameport->timer_lock);
506         init_timer(&gameport->poll_timer);
507         gameport->poll_timer.function = gameport_run_poll_handler;
508         gameport->poll_timer.data = (unsigned long)gameport;
509 }
510
511 /*
512  * Complete gameport port registration.
513  * Driver core will attempt to find appropriate driver for the port.
514  */
515 static void gameport_add_port(struct gameport *gameport)
516 {
517         int error;
518
519         if (gameport->parent)
520                 gameport->parent->child = gameport;
521
522         gameport->speed = gameport_measure_speed(gameport);
523
524         list_add_tail(&gameport->node, &gameport_list);
525
526         if (gameport->io)
527                 dev_info(&gameport->dev, "%s is %s, io %#x, speed %dkHz\n",
528                          gameport->name, gameport->phys, gameport->io, gameport->speed);
529         else
530                 dev_info(&gameport->dev, "%s is %s, speed %dkHz\n",
531                         gameport->name, gameport->phys, gameport->speed);
532
533         error = device_add(&gameport->dev);
534         if (error)
535                 dev_err(&gameport->dev,
536                         "device_add() failed for %s (%s), error: %d\n",
537                         gameport->phys, gameport->name, error);
538 }
539
540 /*
541  * gameport_destroy_port() completes deregistration process and removes
542  * port from the system
543  */
544 static void gameport_destroy_port(struct gameport *gameport)
545 {
546         struct gameport *child;
547
548         child = gameport_get_pending_child(gameport);
549         if (child) {
550                 gameport_remove_pending_events(child);
551                 put_device(&child->dev);
552         }
553
554         if (gameport->parent) {
555                 gameport->parent->child = NULL;
556                 gameport->parent = NULL;
557         }
558
559         if (device_is_registered(&gameport->dev))
560                 device_del(&gameport->dev);
561
562         list_del_init(&gameport->node);
563
564         gameport_remove_pending_events(gameport);
565         put_device(&gameport->dev);
566 }
567
568 /*
569  * Reconnect gameport port and all its children (re-initialize attached devices)
570  */
571 static void gameport_reconnect_port(struct gameport *gameport)
572 {
573         do {
574                 if (!gameport->drv || !gameport->drv->reconnect || gameport->drv->reconnect(gameport)) {
575                         gameport_disconnect_port(gameport);
576                         gameport_find_driver(gameport);
577                         /* Ok, old children are now gone, we are done */
578                         break;
579                 }
580                 gameport = gameport->child;
581         } while (gameport);
582 }
583
584 /*
585  * gameport_disconnect_port() unbinds a port from its driver. As a side effect
586  * all child ports are unbound and destroyed.
587  */
588 static void gameport_disconnect_port(struct gameport *gameport)
589 {
590         struct gameport *s, *parent;
591
592         if (gameport->child) {
593                 /*
594                  * Children ports should be disconnected and destroyed
595                  * first, staring with the leaf one, since we don't want
596                  * to do recursion
597                  */
598                 for (s = gameport; s->child; s = s->child)
599                         /* empty */;
600
601                 do {
602                         parent = s->parent;
603
604                         device_release_driver(&s->dev);
605                         gameport_destroy_port(s);
606                 } while ((s = parent) != gameport);
607         }
608
609         /*
610          * Ok, no children left, now disconnect this port
611          */
612         device_release_driver(&gameport->dev);
613 }
614
615 /*
616  * Submits register request to kgameportd for subsequent execution.
617  * Note that port registration is always asynchronous.
618  */
619 void __gameport_register_port(struct gameport *gameport, struct module *owner)
620 {
621         gameport_init_port(gameport);
622         gameport_queue_event(gameport, owner, GAMEPORT_REGISTER_PORT);
623 }
624 EXPORT_SYMBOL(__gameport_register_port);
625
626 /*
627  * Synchronously unregisters gameport port.
628  */
629 void gameport_unregister_port(struct gameport *gameport)
630 {
631         mutex_lock(&gameport_mutex);
632         gameport_disconnect_port(gameport);
633         gameport_destroy_port(gameport);
634         mutex_unlock(&gameport_mutex);
635 }
636 EXPORT_SYMBOL(gameport_unregister_port);
637
638
639 /*
640  * Gameport driver operations
641  */
642
643 static ssize_t gameport_driver_show_description(struct device_driver *drv, char *buf)
644 {
645         struct gameport_driver *driver = to_gameport_driver(drv);
646         return sprintf(buf, "%s\n", driver->description ? driver->description : "(none)");
647 }
648
649 static struct driver_attribute gameport_driver_attrs[] = {
650         __ATTR(description, S_IRUGO, gameport_driver_show_description, NULL),
651         __ATTR_NULL
652 };
653
654 static int gameport_driver_probe(struct device *dev)
655 {
656         struct gameport *gameport = to_gameport_port(dev);
657         struct gameport_driver *drv = to_gameport_driver(dev->driver);
658
659         drv->connect(gameport, drv);
660         return gameport->drv ? 0 : -ENODEV;
661 }
662
663 static int gameport_driver_remove(struct device *dev)
664 {
665         struct gameport *gameport = to_gameport_port(dev);
666         struct gameport_driver *drv = to_gameport_driver(dev->driver);
667
668         drv->disconnect(gameport);
669         return 0;
670 }
671
672 static void gameport_attach_driver(struct gameport_driver *drv)
673 {
674         int error;
675
676         error = driver_attach(&drv->driver);
677         if (error)
678                 pr_err("driver_attach() failed for %s, error: %d\n",
679                         drv->driver.name, error);
680 }
681
682 int __gameport_register_driver(struct gameport_driver *drv, struct module *owner,
683                                 const char *mod_name)
684 {
685         int error;
686
687         drv->driver.bus = &gameport_bus;
688         drv->driver.owner = owner;
689         drv->driver.mod_name = mod_name;
690
691         /*
692          * Temporarily disable automatic binding because probing
693          * takes long time and we are better off doing it in kgameportd
694          */
695         drv->ignore = true;
696
697         error = driver_register(&drv->driver);
698         if (error) {
699                 pr_err("driver_register() failed for %s, error: %d\n",
700                         drv->driver.name, error);
701                 return error;
702         }
703
704         /*
705          * Reset ignore flag and let kgameportd bind the driver to free ports
706          */
707         drv->ignore = false;
708         error = gameport_queue_event(drv, NULL, GAMEPORT_ATTACH_DRIVER);
709         if (error) {
710                 driver_unregister(&drv->driver);
711                 return error;
712         }
713
714         return 0;
715 }
716 EXPORT_SYMBOL(__gameport_register_driver);
717
718 void gameport_unregister_driver(struct gameport_driver *drv)
719 {
720         struct gameport *gameport;
721
722         mutex_lock(&gameport_mutex);
723
724         drv->ignore = true;     /* so gameport_find_driver ignores it */
725         gameport_remove_pending_events(drv);
726
727 start_over:
728         list_for_each_entry(gameport, &gameport_list, node) {
729                 if (gameport->drv == drv) {
730                         gameport_disconnect_port(gameport);
731                         gameport_find_driver(gameport);
732                         /* we could've deleted some ports, restart */
733                         goto start_over;
734                 }
735         }
736
737         driver_unregister(&drv->driver);
738
739         mutex_unlock(&gameport_mutex);
740 }
741 EXPORT_SYMBOL(gameport_unregister_driver);
742
743 static int gameport_bus_match(struct device *dev, struct device_driver *drv)
744 {
745         struct gameport_driver *gameport_drv = to_gameport_driver(drv);
746
747         return !gameport_drv->ignore;
748 }
749
750 static struct bus_type gameport_bus = {
751         .name           = "gameport",
752         .dev_attrs      = gameport_device_attrs,
753         .drv_attrs      = gameport_driver_attrs,
754         .match          = gameport_bus_match,
755         .probe          = gameport_driver_probe,
756         .remove         = gameport_driver_remove,
757 };
758
759 static void gameport_set_drv(struct gameport *gameport, struct gameport_driver *drv)
760 {
761         mutex_lock(&gameport->drv_mutex);
762         gameport->drv = drv;
763         mutex_unlock(&gameport->drv_mutex);
764 }
765
766 int gameport_open(struct gameport *gameport, struct gameport_driver *drv, int mode)
767 {
768         if (gameport->open) {
769                 if (gameport->open(gameport, mode)) {
770                         return -1;
771                 }
772         } else {
773                 if (mode != GAMEPORT_MODE_RAW)
774                         return -1;
775         }
776
777         gameport_set_drv(gameport, drv);
778         return 0;
779 }
780 EXPORT_SYMBOL(gameport_open);
781
782 void gameport_close(struct gameport *gameport)
783 {
784         del_timer_sync(&gameport->poll_timer);
785         gameport->poll_handler = NULL;
786         gameport->poll_interval = 0;
787         gameport_set_drv(gameport, NULL);
788         if (gameport->close)
789                 gameport->close(gameport);
790 }
791 EXPORT_SYMBOL(gameport_close);
792
793 static int __init gameport_init(void)
794 {
795         int error;
796
797         error = bus_register(&gameport_bus);
798         if (error) {
799                 pr_err("failed to register gameport bus, error: %d\n", error);
800                 return error;
801         }
802
803
804         return 0;
805 }
806
807 static void __exit gameport_exit(void)
808 {
809         bus_unregister(&gameport_bus);
810
811         /*
812          * There should not be any outstanding events but work may
813          * still be scheduled so simply cancel it.
814          */
815         cancel_work_sync(&gameport_event_work);
816 }
817
818 subsys_initcall(gameport_init);
819 module_exit(gameport_exit);