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#include <linux/timekeeping.h>
27
28/*#include <asm/io.h>*/
29
30MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
31MODULE_DESCRIPTION("Generic gameport layer");
32MODULE_LICENSE("GPL");
33
34static bool use_ktime = true;
35module_param(use_ktime, bool, 0400);
36MODULE_PARM_DESC(use_ktime, "Use ktime for measuring I/O speed");
37
38/*
39 * gameport_mutex protects entire gameport subsystem and is taken
40 * every time gameport port or driver registrered or unregistered.
41 */
42static DEFINE_MUTEX(gameport_mutex);
43
44static LIST_HEAD(gameport_list);
45
46static struct bus_type gameport_bus;
47
48static void gameport_add_port(struct gameport *gameport);
49static void gameport_attach_driver(struct gameport_driver *drv);
50static void gameport_reconnect_port(struct gameport *gameport);
51static void gameport_disconnect_port(struct gameport *gameport);
52
53#if defined(__i386__)
54
55#include <linux/i8253.h>
56
57#define DELTA(x,y) ((y)-(x)+((y)<(x)?1193182/HZ:0))
58#define GET_TIME(x) do { x = get_time_pit(); } while (0)
59
60static unsigned int get_time_pit(void)
61{
62 unsigned long flags;
63 unsigned int count;
64
65 raw_spin_lock_irqsave(&i8253_lock, flags);
66 outb_p(0x00, 0x43);
67 count = inb_p(0x40);
68 count |= inb_p(0x40) << 8;
69 raw_spin_unlock_irqrestore(&i8253_lock, flags);
70
71 return count;
72}
73
74#endif
75
76
77
78/*
79 * gameport_measure_speed() measures the gameport i/o speed.
80 */
81
82static int gameport_measure_speed(struct gameport *gameport)
83{
84 unsigned int i, t, tx;
85 u64 t1, t2, t3;
86 unsigned long flags;
87
88 if (gameport_open(gameport, NULL, GAMEPORT_MODE_RAW))
89 return 0;
90
91 tx = ~0;
92
93 for (i = 0; i < 50; i++) {
94 local_irq_save(flags);
95 t1 = ktime_get_ns();
96 for (t = 0; t < 50; t++)
97 gameport_read(gameport);
98 t2 = ktime_get_ns();
99 t3 = ktime_get_ns();
100 local_irq_restore(flags);
101 udelay(i * 10);
102 t = (t2 - t1) - (t3 - t2);
103 if (t < tx)
104 tx = t;
105 }
106
107 gameport_close(gameport);
108 t = 1000000 * 50;
109 if (tx)
110 t /= tx;
111 return t;
112}
113
114static int old_gameport_measure_speed(struct gameport *gameport)
115{
116#if defined(__i386__)
117
118 unsigned int i, t, t1, t2, t3, tx;
119 unsigned long 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 GET_TIME(t1);
129 for (t = 0; t < 50; t++) gameport_read(gameport);
130 GET_TIME(t2);
131 GET_TIME(t3);
132 local_irq_restore(flags);
133 udelay(i * 10);
134 if ((t = DELTA(t2,t1) - DELTA(t3,t2)) < tx) tx = t;
135 }
136
137 gameport_close(gameport);
138 return 59659 / (tx < 1 ? 1 : tx);
139
140#elif defined (__x86_64__)
141
142 unsigned int i, t;
143 unsigned long tx, t1, t2, flags;
144
145 if (gameport_open(gameport, NULL, GAMEPORT_MODE_RAW))
146 return 0;
147
148 tx = 1 << 30;
149
150 for(i = 0; i < 50; i++) {
151 local_irq_save(flags);
152 t1 = rdtsc();
153 for (t = 0; t < 50; t++) gameport_read(gameport);
154 t2 = rdtsc();
155 local_irq_restore(flags);
156 udelay(i * 10);
157 if (t2 - t1 < tx) tx = t2 - t1;
158 }
159
160 gameport_close(gameport);
161 return (this_cpu_read(cpu_info.loops_per_jiffy) *
162 (unsigned long)HZ / (1000 / 50)) / (tx < 1 ? 1 : tx);
163
164#else
165
166 unsigned int j, t = 0;
167
168 if (gameport_open(gameport, NULL, GAMEPORT_MODE_RAW))
169 return 0;
170
171 j = jiffies; while (j == jiffies);
172 j = jiffies; while (j == jiffies) { t++; gameport_read(gameport); }
173
174 gameport_close(gameport);
175 return t * HZ / 1000;
176
177#endif
178}
179
180void gameport_start_polling(struct gameport *gameport)
181{
182 spin_lock(&gameport->timer_lock);
183
184 if (!gameport->poll_cnt++) {
185 BUG_ON(!gameport->poll_handler);
186 BUG_ON(!gameport->poll_interval);
187 mod_timer(&gameport->poll_timer, jiffies + msecs_to_jiffies(gameport->poll_interval));
188 }
189
190 spin_unlock(&gameport->timer_lock);
191}
192EXPORT_SYMBOL(gameport_start_polling);
193
194void gameport_stop_polling(struct gameport *gameport)
195{
196 spin_lock(&gameport->timer_lock);
197
198 if (!--gameport->poll_cnt)
199 del_timer(&gameport->poll_timer);
200
201 spin_unlock(&gameport->timer_lock);
202}
203EXPORT_SYMBOL(gameport_stop_polling);
204
205static void gameport_run_poll_handler(struct timer_list *t)
206{
207 struct gameport *gameport = from_timer(gameport, t, poll_timer);
208
209 gameport->poll_handler(gameport);
210 if (gameport->poll_cnt)
211 mod_timer(&gameport->poll_timer, jiffies + msecs_to_jiffies(gameport->poll_interval));
212}
213
214/*
215 * Basic gameport -> driver core mappings
216 */
217
218static int gameport_bind_driver(struct gameport *gameport, struct gameport_driver *drv)
219{
220 int error;
221
222 gameport->dev.driver = &drv->driver;
223 if (drv->connect(gameport, drv)) {
224 gameport->dev.driver = NULL;
225 return -ENODEV;
226 }
227
228 error = device_bind_driver(&gameport->dev);
229 if (error) {
230 dev_warn(&gameport->dev,
231 "device_bind_driver() failed for %s (%s) and %s, error: %d\n",
232 gameport->phys, gameport->name,
233 drv->description, error);
234 drv->disconnect(gameport);
235 gameport->dev.driver = NULL;
236 return error;
237 }
238
239 return 0;
240}
241
242static void gameport_find_driver(struct gameport *gameport)
243{
244 int error;
245
246 error = device_attach(&gameport->dev);
247 if (error < 0)
248 dev_warn(&gameport->dev,
249 "device_attach() failed for %s (%s), error: %d\n",
250 gameport->phys, gameport->name, error);
251}
252
253
254/*
255 * Gameport event processing.
256 */
257
258enum gameport_event_type {
259 GAMEPORT_REGISTER_PORT,
260 GAMEPORT_ATTACH_DRIVER,
261};
262
263struct gameport_event {
264 enum gameport_event_type type;
265 void *object;
266 struct module *owner;
267 struct list_head node;
268};
269
270static DEFINE_SPINLOCK(gameport_event_lock); /* protects gameport_event_list */
271static LIST_HEAD(gameport_event_list);
272
273static struct gameport_event *gameport_get_event(void)
274{
275 struct gameport_event *event = NULL;
276 unsigned long flags;
277
278 spin_lock_irqsave(&gameport_event_lock, flags);
279
280 if (!list_empty(&gameport_event_list)) {
281 event = list_first_entry(&gameport_event_list,
282 struct gameport_event, node);
283 list_del_init(&event->node);
284 }
285
286 spin_unlock_irqrestore(&gameport_event_lock, flags);
287 return event;
288}
289
290static void gameport_free_event(struct gameport_event *event)
291{
292 module_put(event->owner);
293 kfree(event);
294}
295
296static void gameport_remove_duplicate_events(struct gameport_event *event)
297{
298 struct gameport_event *e, *next;
299 unsigned long flags;
300
301 spin_lock_irqsave(&gameport_event_lock, flags);
302
303 list_for_each_entry_safe(e, next, &gameport_event_list, node) {
304 if (event->object == e->object) {
305 /*
306 * If this event is of different type we should not
307 * look further - we only suppress duplicate events
308 * that were sent back-to-back.
309 */
310 if (event->type != e->type)
311 break;
312
313 list_del_init(&e->node);
314 gameport_free_event(e);
315 }
316 }
317
318 spin_unlock_irqrestore(&gameport_event_lock, flags);
319}
320
321
322static void gameport_handle_events(struct work_struct *work)
323{
324 struct gameport_event *event;
325
326 mutex_lock(&gameport_mutex);
327
328 /*
329 * Note that we handle only one event here to give swsusp
330 * a chance to freeze kgameportd thread. Gameport events
331 * should be pretty rare so we are not concerned about
332 * taking performance hit.
333 */
334 if ((event = gameport_get_event())) {
335
336 switch (event->type) {
337
338 case GAMEPORT_REGISTER_PORT:
339 gameport_add_port(event->object);
340 break;
341
342 case GAMEPORT_ATTACH_DRIVER:
343 gameport_attach_driver(event->object);
344 break;
345 }
346
347 gameport_remove_duplicate_events(event);
348 gameport_free_event(event);
349 }
350
351 mutex_unlock(&gameport_mutex);
352}
353
354static DECLARE_WORK(gameport_event_work, gameport_handle_events);
355
356static int gameport_queue_event(void *object, struct module *owner,
357 enum gameport_event_type event_type)
358{
359 unsigned long flags;
360 struct gameport_event *event;
361 int retval = 0;
362
363 spin_lock_irqsave(&gameport_event_lock, flags);
364
365 /*
366 * Scan event list for the other events for the same gameport port,
367 * starting with the most recent one. If event is the same we
368 * do not need add new one. If event is of different type we
369 * need to add this event and should not look further because
370 * we need to preserve sequence of distinct events.
371 */
372 list_for_each_entry_reverse(event, &gameport_event_list, node) {
373 if (event->object == object) {
374 if (event->type == event_type)
375 goto out;
376 break;
377 }
378 }
379
380 event = kmalloc(sizeof(struct gameport_event), GFP_ATOMIC);
381 if (!event) {
382 pr_err("Not enough memory to queue event %d\n", event_type);
383 retval = -ENOMEM;
384 goto out;
385 }
386
387 if (!try_module_get(owner)) {
388 pr_warn("Can't get module reference, dropping event %d\n",
389 event_type);
390 kfree(event);
391 retval = -EINVAL;
392 goto out;
393 }
394
395 event->type = event_type;
396 event->object = object;
397 event->owner = owner;
398
399 list_add_tail(&event->node, &gameport_event_list);
400 queue_work(system_long_wq, &gameport_event_work);
401
402out:
403 spin_unlock_irqrestore(&gameport_event_lock, flags);
404 return retval;
405}
406
407/*
408 * Remove all events that have been submitted for a given object,
409 * be it a gameport port or a driver.
410 */
411static void gameport_remove_pending_events(void *object)
412{
413 struct gameport_event *event, *next;
414 unsigned long flags;
415
416 spin_lock_irqsave(&gameport_event_lock, flags);
417
418 list_for_each_entry_safe(event, next, &gameport_event_list, node) {
419 if (event->object == object) {
420 list_del_init(&event->node);
421 gameport_free_event(event);
422 }
423 }
424
425 spin_unlock_irqrestore(&gameport_event_lock, flags);
426}
427
428/*
429 * Destroy child gameport port (if any) that has not been fully registered yet.
430 *
431 * Note that we rely on the fact that port can have only one child and therefore
432 * only one child registration request can be pending. Additionally, children
433 * are registered by driver's connect() handler so there can't be a grandchild
434 * pending registration together with a child.
435 */
436static struct gameport *gameport_get_pending_child(struct gameport *parent)
437{
438 struct gameport_event *event;
439 struct gameport *gameport, *child = NULL;
440 unsigned long flags;
441
442 spin_lock_irqsave(&gameport_event_lock, flags);
443
444 list_for_each_entry(event, &gameport_event_list, node) {
445 if (event->type == GAMEPORT_REGISTER_PORT) {
446 gameport = event->object;
447 if (gameport->parent == parent) {
448 child = gameport;
449 break;
450 }
451 }
452 }
453
454 spin_unlock_irqrestore(&gameport_event_lock, flags);
455 return child;
456}
457
458/*
459 * Gameport port operations
460 */
461
462static ssize_t gameport_description_show(struct device *dev, struct device_attribute *attr, char *buf)
463{
464 struct gameport *gameport = to_gameport_port(dev);
465
466 return sprintf(buf, "%s\n", gameport->name);
467}
468static DEVICE_ATTR(description, S_IRUGO, gameport_description_show, NULL);
469
470static ssize_t drvctl_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
471{
472 struct gameport *gameport = to_gameport_port(dev);
473 struct device_driver *drv;
474 int error;
475
476 error = mutex_lock_interruptible(&gameport_mutex);
477 if (error)
478 return error;
479
480 if (!strncmp(buf, "none", count)) {
481 gameport_disconnect_port(gameport);
482 } else if (!strncmp(buf, "reconnect", count)) {
483 gameport_reconnect_port(gameport);
484 } else if (!strncmp(buf, "rescan", count)) {
485 gameport_disconnect_port(gameport);
486 gameport_find_driver(gameport);
487 } else if ((drv = driver_find(buf, &gameport_bus)) != NULL) {
488 gameport_disconnect_port(gameport);
489 error = gameport_bind_driver(gameport, to_gameport_driver(drv));
490 } else {
491 error = -EINVAL;
492 }
493
494 mutex_unlock(&gameport_mutex);
495
496 return error ? error : count;
497}
498static DEVICE_ATTR_WO(drvctl);
499
500static struct attribute *gameport_device_attrs[] = {
501 &dev_attr_description.attr,
502 &dev_attr_drvctl.attr,
503 NULL,
504};
505ATTRIBUTE_GROUPS(gameport_device);
506
507static 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
515void 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}
523EXPORT_SYMBOL(gameport_set_phys);
524
525/*
526 * Prepare gameport port for registration.
527 */
528static void gameport_init_port(struct gameport *gameport)
529{
530 static atomic_t gameport_no = ATOMIC_INIT(-1);
531
532 __module_get(THIS_MODULE);
533
534 mutex_init(&gameport->drv_mutex);
535 device_initialize(&gameport->dev);
536 dev_set_name(&gameport->dev, "gameport%lu",
537 (unsigned long)atomic_inc_return(&gameport_no));
538 gameport->dev.bus = &gameport_bus;
539 gameport->dev.release = gameport_release_port;
540 if (gameport->parent)
541 gameport->dev.parent = &gameport->parent->dev;
542
543 INIT_LIST_HEAD(&gameport->node);
544 spin_lock_init(&gameport->timer_lock);
545 timer_setup(&gameport->poll_timer, gameport_run_poll_handler, 0);
546}
547
548/*
549 * Complete gameport port registration.
550 * Driver core will attempt to find appropriate driver for the port.
551 */
552static void gameport_add_port(struct gameport *gameport)
553{
554 int error;
555
556 if (gameport->parent)
557 gameport->parent->child = gameport;
558
559 gameport->speed = use_ktime ?
560 gameport_measure_speed(gameport) :
561 old_gameport_measure_speed(gameport);
562
563 list_add_tail(&gameport->node, &gameport_list);
564
565 if (gameport->io)
566 dev_info(&gameport->dev, "%s is %s, io %#x, speed %dkHz\n",
567 gameport->name, gameport->phys, gameport->io, gameport->speed);
568 else
569 dev_info(&gameport->dev, "%s is %s, speed %dkHz\n",
570 gameport->name, gameport->phys, gameport->speed);
571
572 error = device_add(&gameport->dev);
573 if (error)
574 dev_err(&gameport->dev,
575 "device_add() failed for %s (%s), error: %d\n",
576 gameport->phys, gameport->name, error);
577}
578
579/*
580 * gameport_destroy_port() completes deregistration process and removes
581 * port from the system
582 */
583static void gameport_destroy_port(struct gameport *gameport)
584{
585 struct gameport *child;
586
587 child = gameport_get_pending_child(gameport);
588 if (child) {
589 gameport_remove_pending_events(child);
590 put_device(&child->dev);
591 }
592
593 if (gameport->parent) {
594 gameport->parent->child = NULL;
595 gameport->parent = NULL;
596 }
597
598 if (device_is_registered(&gameport->dev))
599 device_del(&gameport->dev);
600
601 list_del_init(&gameport->node);
602
603 gameport_remove_pending_events(gameport);
604 put_device(&gameport->dev);
605}
606
607/*
608 * Reconnect gameport port and all its children (re-initialize attached devices)
609 */
610static void gameport_reconnect_port(struct gameport *gameport)
611{
612 do {
613 if (!gameport->drv || !gameport->drv->reconnect || gameport->drv->reconnect(gameport)) {
614 gameport_disconnect_port(gameport);
615 gameport_find_driver(gameport);
616 /* Ok, old children are now gone, we are done */
617 break;
618 }
619 gameport = gameport->child;
620 } while (gameport);
621}
622
623/*
624 * gameport_disconnect_port() unbinds a port from its driver. As a side effect
625 * all child ports are unbound and destroyed.
626 */
627static void gameport_disconnect_port(struct gameport *gameport)
628{
629 struct gameport *s, *parent;
630
631 if (gameport->child) {
632 /*
633 * Children ports should be disconnected and destroyed
634 * first, staring with the leaf one, since we don't want
635 * to do recursion
636 */
637 for (s = gameport; s->child; s = s->child)
638 /* empty */;
639
640 do {
641 parent = s->parent;
642
643 device_release_driver(&s->dev);
644 gameport_destroy_port(s);
645 } while ((s = parent) != gameport);
646 }
647
648 /*
649 * Ok, no children left, now disconnect this port
650 */
651 device_release_driver(&gameport->dev);
652}
653
654/*
655 * Submits register request to kgameportd for subsequent execution.
656 * Note that port registration is always asynchronous.
657 */
658void __gameport_register_port(struct gameport *gameport, struct module *owner)
659{
660 gameport_init_port(gameport);
661 gameport_queue_event(gameport, owner, GAMEPORT_REGISTER_PORT);
662}
663EXPORT_SYMBOL(__gameport_register_port);
664
665/*
666 * Synchronously unregisters gameport port.
667 */
668void gameport_unregister_port(struct gameport *gameport)
669{
670 mutex_lock(&gameport_mutex);
671 gameport_disconnect_port(gameport);
672 gameport_destroy_port(gameport);
673 mutex_unlock(&gameport_mutex);
674}
675EXPORT_SYMBOL(gameport_unregister_port);
676
677
678/*
679 * Gameport driver operations
680 */
681
682static ssize_t description_show(struct device_driver *drv, char *buf)
683{
684 struct gameport_driver *driver = to_gameport_driver(drv);
685 return sprintf(buf, "%s\n", driver->description ? driver->description : "(none)");
686}
687static DRIVER_ATTR_RO(description);
688
689static struct attribute *gameport_driver_attrs[] = {
690 &driver_attr_description.attr,
691 NULL
692};
693ATTRIBUTE_GROUPS(gameport_driver);
694
695static int gameport_driver_probe(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->connect(gameport, drv);
701 return gameport->drv ? 0 : -ENODEV;
702}
703
704static int gameport_driver_remove(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->disconnect(gameport);
710 return 0;
711}
712
713static void gameport_attach_driver(struct gameport_driver *drv)
714{
715 int error;
716
717 error = driver_attach(&drv->driver);
718 if (error)
719 pr_err("driver_attach() failed for %s, error: %d\n",
720 drv->driver.name, error);
721}
722
723int __gameport_register_driver(struct gameport_driver *drv, struct module *owner,
724 const char *mod_name)
725{
726 int error;
727
728 drv->driver.bus = &gameport_bus;
729 drv->driver.owner = owner;
730 drv->driver.mod_name = mod_name;
731
732 /*
733 * Temporarily disable automatic binding because probing
734 * takes long time and we are better off doing it in kgameportd
735 */
736 drv->ignore = true;
737
738 error = driver_register(&drv->driver);
739 if (error) {
740 pr_err("driver_register() failed for %s, error: %d\n",
741 drv->driver.name, error);
742 return error;
743 }
744
745 /*
746 * Reset ignore flag and let kgameportd bind the driver to free ports
747 */
748 drv->ignore = false;
749 error = gameport_queue_event(drv, NULL, GAMEPORT_ATTACH_DRIVER);
750 if (error) {
751 driver_unregister(&drv->driver);
752 return error;
753 }
754
755 return 0;
756}
757EXPORT_SYMBOL(__gameport_register_driver);
758
759void gameport_unregister_driver(struct gameport_driver *drv)
760{
761 struct gameport *gameport;
762
763 mutex_lock(&gameport_mutex);
764
765 drv->ignore = true; /* so gameport_find_driver ignores it */
766 gameport_remove_pending_events(drv);
767
768start_over:
769 list_for_each_entry(gameport, &gameport_list, node) {
770 if (gameport->drv == drv) {
771 gameport_disconnect_port(gameport);
772 gameport_find_driver(gameport);
773 /* we could've deleted some ports, restart */
774 goto start_over;
775 }
776 }
777
778 driver_unregister(&drv->driver);
779
780 mutex_unlock(&gameport_mutex);
781}
782EXPORT_SYMBOL(gameport_unregister_driver);
783
784static int gameport_bus_match(struct device *dev, struct device_driver *drv)
785{
786 struct gameport_driver *gameport_drv = to_gameport_driver(drv);
787
788 return !gameport_drv->ignore;
789}
790
791static struct bus_type gameport_bus = {
792 .name = "gameport",
793 .dev_groups = gameport_device_groups,
794 .drv_groups = gameport_driver_groups,
795 .match = gameport_bus_match,
796 .probe = gameport_driver_probe,
797 .remove = gameport_driver_remove,
798};
799
800static void gameport_set_drv(struct gameport *gameport, struct gameport_driver *drv)
801{
802 mutex_lock(&gameport->drv_mutex);
803 gameport->drv = drv;
804 mutex_unlock(&gameport->drv_mutex);
805}
806
807int gameport_open(struct gameport *gameport, struct gameport_driver *drv, int mode)
808{
809 if (gameport->open) {
810 if (gameport->open(gameport, mode)) {
811 return -1;
812 }
813 } else {
814 if (mode != GAMEPORT_MODE_RAW)
815 return -1;
816 }
817
818 gameport_set_drv(gameport, drv);
819 return 0;
820}
821EXPORT_SYMBOL(gameport_open);
822
823void gameport_close(struct gameport *gameport)
824{
825 del_timer_sync(&gameport->poll_timer);
826 gameport->poll_handler = NULL;
827 gameport->poll_interval = 0;
828 gameport_set_drv(gameport, NULL);
829 if (gameport->close)
830 gameport->close(gameport);
831}
832EXPORT_SYMBOL(gameport_close);
833
834static int __init gameport_init(void)
835{
836 int error;
837
838 error = bus_register(&gameport_bus);
839 if (error) {
840 pr_err("failed to register gameport bus, error: %d\n", error);
841 return error;
842 }
843
844
845 return 0;
846}
847
848static void __exit gameport_exit(void)
849{
850 bus_unregister(&gameport_bus);
851
852 /*
853 * There should not be any outstanding events but work may
854 * still be scheduled so simply cancel it.
855 */
856 cancel_work_sync(&gameport_event_work);
857}
858
859subsys_initcall(gameport_init);
860module_exit(gameport_exit);
861