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/slab.h>
21 #include <linux/delay.h>
22 #include <linux/kthread.h>
23 #include <linux/sched.h> /* HZ */
24 #include <linux/mutex.h>
25 #include <linux/freezer.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 <asm/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 spin_lock_irqsave(&i8253_lock, flags);
61 outb_p(0x00, 0x43);
62 count = inb_p(0x40);
63 count |= inb_p(0x40) << 8;
64 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 (cpu_data(raw_smp_processor_id()).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 printk(KERN_WARNING
194 "gameport: device_bind_driver() failed "
195 "for %s (%s) and %s, error: %d\n",
196 gameport->phys, gameport->name,
197 drv->description, error);
198 drv->disconnect(gameport);
199 gameport->dev.driver = NULL;
200 return error;
201 }
202
203 return 0;
204 }
205
206 static void gameport_find_driver(struct gameport *gameport)
207 {
208 int error;
209
210 error = device_attach(&gameport->dev);
211 if (error < 0)
212 printk(KERN_WARNING
213 "gameport: device_attach() failed for %s (%s), error: %d\n",
214 gameport->phys, gameport->name, error);
215 }
216
217
218 /*
219 * Gameport event processing.
220 */
221
222 enum gameport_event_type {
223 GAMEPORT_REGISTER_PORT,
224 GAMEPORT_ATTACH_DRIVER,
225 };
226
227 struct gameport_event {
228 enum gameport_event_type type;
229 void *object;
230 struct module *owner;
231 struct list_head node;
232 };
233
234 static DEFINE_SPINLOCK(gameport_event_lock); /* protects gameport_event_list */
235 static LIST_HEAD(gameport_event_list);
236 static DECLARE_WAIT_QUEUE_HEAD(gameport_wait);
237 static struct task_struct *gameport_task;
238
239 static int gameport_queue_event(void *object, struct module *owner,
240 enum gameport_event_type event_type)
241 {
242 unsigned long flags;
243 struct gameport_event *event;
244 int retval = 0;
245
246 spin_lock_irqsave(&gameport_event_lock, flags);
247
248 /*
249 * Scan event list for the other events for the same gameport port,
250 * starting with the most recent one. If event is the same we
251 * do not need add new one. If event is of different type we
252 * need to add this event and should not look further because
253 * we need to preseve sequence of distinct events.
254 */
255 list_for_each_entry_reverse(event, &gameport_event_list, node) {
256 if (event->object == object) {
257 if (event->type == event_type)
258 goto out;
259 break;
260 }
261 }
262
263 event = kmalloc(sizeof(struct gameport_event), GFP_ATOMIC);
264 if (!event) {
265 printk(KERN_ERR
266 "gameport: Not enough memory to queue event %d\n",
267 event_type);
268 retval = -ENOMEM;
269 goto out;
270 }
271
272 if (!try_module_get(owner)) {
273 printk(KERN_WARNING
274 "gameport: Can't get module reference, dropping event %d\n",
275 event_type);
276 kfree(event);
277 retval = -EINVAL;
278 goto out;
279 }
280
281 event->type = event_type;
282 event->object = object;
283 event->owner = owner;
284
285 list_add_tail(&event->node, &gameport_event_list);
286 wake_up(&gameport_wait);
287
288 out:
289 spin_unlock_irqrestore(&gameport_event_lock, flags);
290 return retval;
291 }
292
293 static void gameport_free_event(struct gameport_event *event)
294 {
295 module_put(event->owner);
296 kfree(event);
297 }
298
299 static void gameport_remove_duplicate_events(struct gameport_event *event)
300 {
301 struct list_head *node, *next;
302 struct gameport_event *e;
303 unsigned long flags;
304
305 spin_lock_irqsave(&gameport_event_lock, flags);
306
307 list_for_each_safe(node, next, &gameport_event_list) {
308 e = list_entry(node, struct gameport_event, node);
309 if (event->object == e->object) {
310 /*
311 * If this event is of different type we should not
312 * look further - we only suppress duplicate events
313 * that were sent back-to-back.
314 */
315 if (event->type != e->type)
316 break;
317
318 list_del_init(node);
319 gameport_free_event(e);
320 }
321 }
322
323 spin_unlock_irqrestore(&gameport_event_lock, flags);
324 }
325
326 static struct gameport_event *gameport_get_event(void)
327 {
328 struct gameport_event *event;
329 struct list_head *node;
330 unsigned long flags;
331
332 spin_lock_irqsave(&gameport_event_lock, flags);
333
334 if (list_empty(&gameport_event_list)) {
335 spin_unlock_irqrestore(&gameport_event_lock, flags);
336 return NULL;
337 }
338
339 node = gameport_event_list.next;
340 event = list_entry(node, struct gameport_event, node);
341 list_del_init(node);
342
343 spin_unlock_irqrestore(&gameport_event_lock, flags);
344
345 return event;
346 }
347
348 static void gameport_handle_event(void)
349 {
350 struct gameport_event *event;
351
352 mutex_lock(&gameport_mutex);
353
354 /*
355 * Note that we handle only one event here to give swsusp
356 * a chance to freeze kgameportd thread. Gameport events
357 * should be pretty rare so we are not concerned about
358 * taking performance hit.
359 */
360 if ((event = gameport_get_event())) {
361
362 switch (event->type) {
363 case GAMEPORT_REGISTER_PORT:
364 gameport_add_port(event->object);
365 break;
366
367 case GAMEPORT_ATTACH_DRIVER:
368 gameport_attach_driver(event->object);
369 break;
370
371 default:
372 break;
373 }
374
375 gameport_remove_duplicate_events(event);
376 gameport_free_event(event);
377 }
378
379 mutex_unlock(&gameport_mutex);
380 }
381
382 /*
383 * Remove all events that have been submitted for a given object,
384 * be it a gameport port or a driver.
385 */
386 static void gameport_remove_pending_events(void *object)
387 {
388 struct list_head *node, *next;
389 struct gameport_event *event;
390 unsigned long flags;
391
392 spin_lock_irqsave(&gameport_event_lock, flags);
393
394 list_for_each_safe(node, next, &gameport_event_list) {
395 event = list_entry(node, struct gameport_event, node);
396 if (event->object == object) {
397 list_del_init(node);
398 gameport_free_event(event);
399 }
400 }
401
402 spin_unlock_irqrestore(&gameport_event_lock, flags);
403 }
404
405 /*
406 * Destroy child gameport port (if any) that has not been fully registered yet.
407 *
408 * Note that we rely on the fact that port can have only one child and therefore
409 * only one child registration request can be pending. Additionally, children
410 * are registered by driver's connect() handler so there can't be a grandchild
411 * pending registration together with a child.
412 */
413 static struct gameport *gameport_get_pending_child(struct gameport *parent)
414 {
415 struct gameport_event *event;
416 struct gameport *gameport, *child = NULL;
417 unsigned long flags;
418
419 spin_lock_irqsave(&gameport_event_lock, flags);
420
421 list_for_each_entry(event, &gameport_event_list, node) {
422 if (event->type == GAMEPORT_REGISTER_PORT) {
423 gameport = event->object;
424 if (gameport->parent == parent) {
425 child = gameport;
426 break;
427 }
428 }
429 }
430
431 spin_unlock_irqrestore(&gameport_event_lock, flags);
432 return child;
433 }
434
435 static int gameport_thread(void *nothing)
436 {
437 set_freezable();
438 do {
439 gameport_handle_event();
440 wait_event_freezable(gameport_wait,
441 kthread_should_stop() || !list_empty(&gameport_event_list));
442 } while (!kthread_should_stop());
443
444 printk(KERN_DEBUG "gameport: kgameportd exiting\n");
445 return 0;
446 }
447
448
449 /*
450 * Gameport port operations
451 */
452
453 static ssize_t gameport_show_description(struct device *dev, struct device_attribute *attr, char *buf)
454 {
455 struct gameport *gameport = to_gameport_port(dev);
456 return sprintf(buf, "%s\n", gameport->name);
457 }
458
459 static ssize_t gameport_rebind_driver(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
460 {
461 struct gameport *gameport = to_gameport_port(dev);
462 struct device_driver *drv;
463 int error;
464
465 error = mutex_lock_interruptible(&gameport_mutex);
466 if (error)
467 return error;
468
469 if (!strncmp(buf, "none", count)) {
470 gameport_disconnect_port(gameport);
471 } else if (!strncmp(buf, "reconnect", count)) {
472 gameport_reconnect_port(gameport);
473 } else if (!strncmp(buf, "rescan", count)) {
474 gameport_disconnect_port(gameport);
475 gameport_find_driver(gameport);
476 } else if ((drv = driver_find(buf, &gameport_bus)) != NULL) {
477 gameport_disconnect_port(gameport);
478 error = gameport_bind_driver(gameport, to_gameport_driver(drv));
479 put_driver(drv);
480 } else {
481 error = -EINVAL;
482 }
483
484 mutex_unlock(&gameport_mutex);
485
486 return error ? error : count;
487 }
488
489 static struct device_attribute gameport_device_attrs[] = {
490 __ATTR(description, S_IRUGO, gameport_show_description, NULL),
491 __ATTR(drvctl, S_IWUSR, NULL, gameport_rebind_driver),
492 __ATTR_NULL
493 };
494
495 static void gameport_release_port(struct device *dev)
496 {
497 struct gameport *gameport = to_gameport_port(dev);
498
499 kfree(gameport);
500 module_put(THIS_MODULE);
501 }
502
503 void gameport_set_phys(struct gameport *gameport, const char *fmt, ...)
504 {
505 va_list args;
506
507 va_start(args, fmt);
508 vsnprintf(gameport->phys, sizeof(gameport->phys), fmt, args);
509 va_end(args);
510 }
511 EXPORT_SYMBOL(gameport_set_phys);
512
513 /*
514 * Prepare gameport port for registration.
515 */
516 static void gameport_init_port(struct gameport *gameport)
517 {
518 static atomic_t gameport_no = ATOMIC_INIT(0);
519
520 __module_get(THIS_MODULE);
521
522 mutex_init(&gameport->drv_mutex);
523 device_initialize(&gameport->dev);
524 dev_set_name(&gameport->dev, "gameport%lu", (unsigned long)atomic_inc_return(&gameport_no) - 1);
525 gameport->dev.bus = &gameport_bus;
526 gameport->dev.release = gameport_release_port;
527 if (gameport->parent)
528 gameport->dev.parent = &gameport->parent->dev;
529
530 INIT_LIST_HEAD(&gameport->node);
531 spin_lock_init(&gameport->timer_lock);
532 init_timer(&gameport->poll_timer);
533 gameport->poll_timer.function = gameport_run_poll_handler;
534 gameport->poll_timer.data = (unsigned long)gameport;
535 }
536
537 /*
538 * Complete gameport port registration.
539 * Driver core will attempt to find appropriate driver for the port.
540 */
541 static void gameport_add_port(struct gameport *gameport)
542 {
543 int error;
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 error = device_add(&gameport->dev);
560 if (error)
561 printk(KERN_ERR
562 "gameport: device_add() failed for %s (%s), error: %d\n",
563 gameport->phys, gameport->name, error);
564 else
565 gameport->registered = 1;
566 }
567
568 /*
569 * gameport_destroy_port() completes deregistration process and removes
570 * port from the system
571 */
572 static void gameport_destroy_port(struct gameport *gameport)
573 {
574 struct gameport *child;
575
576 child = gameport_get_pending_child(gameport);
577 if (child) {
578 gameport_remove_pending_events(child);
579 put_device(&child->dev);
580 }
581
582 if (gameport->parent) {
583 gameport->parent->child = NULL;
584 gameport->parent = NULL;
585 }
586
587 if (gameport->registered) {
588 device_del(&gameport->dev);
589 gameport->registered = 0;
590 }
591
592 list_del_init(&gameport->node);
593
594 gameport_remove_pending_events(gameport);
595 put_device(&gameport->dev);
596 }
597
598 /*
599 * Reconnect gameport port and all its children (re-initialize attached devices)
600 */
601 static void gameport_reconnect_port(struct gameport *gameport)
602 {
603 do {
604 if (!gameport->drv || !gameport->drv->reconnect || gameport->drv->reconnect(gameport)) {
605 gameport_disconnect_port(gameport);
606 gameport_find_driver(gameport);
607 /* Ok, old children are now gone, we are done */
608 break;
609 }
610 gameport = gameport->child;
611 } while (gameport);
612 }
613
614 /*
615 * gameport_disconnect_port() unbinds a port from its driver. As a side effect
616 * all child ports are unbound and destroyed.
617 */
618 static void gameport_disconnect_port(struct gameport *gameport)
619 {
620 struct gameport *s, *parent;
621
622 if (gameport->child) {
623 /*
624 * Children ports should be disconnected and destroyed
625 * first, staring with the leaf one, since we don't want
626 * to do recursion
627 */
628 for (s = gameport; s->child; s = s->child)
629 /* empty */;
630
631 do {
632 parent = s->parent;
633
634 device_release_driver(&s->dev);
635 gameport_destroy_port(s);
636 } while ((s = parent) != gameport);
637 }
638
639 /*
640 * Ok, no children left, now disconnect this port
641 */
642 device_release_driver(&gameport->dev);
643 }
644
645 /*
646 * Submits register request to kgameportd for subsequent execution.
647 * Note that port registration is always asynchronous.
648 */
649 void __gameport_register_port(struct gameport *gameport, struct module *owner)
650 {
651 gameport_init_port(gameport);
652 gameport_queue_event(gameport, owner, GAMEPORT_REGISTER_PORT);
653 }
654 EXPORT_SYMBOL(__gameport_register_port);
655
656 /*
657 * Synchronously unregisters gameport port.
658 */
659 void gameport_unregister_port(struct gameport *gameport)
660 {
661 mutex_lock(&gameport_mutex);
662 gameport_disconnect_port(gameport);
663 gameport_destroy_port(gameport);
664 mutex_unlock(&gameport_mutex);
665 }
666 EXPORT_SYMBOL(gameport_unregister_port);
667
668
669 /*
670 * Gameport driver operations
671 */
672
673 static ssize_t gameport_driver_show_description(struct device_driver *drv, char *buf)
674 {
675 struct gameport_driver *driver = to_gameport_driver(drv);
676 return sprintf(buf, "%s\n", driver->description ? driver->description : "(none)");
677 }
678
679 static struct driver_attribute gameport_driver_attrs[] = {
680 __ATTR(description, S_IRUGO, gameport_driver_show_description, NULL),
681 __ATTR_NULL
682 };
683
684 static int gameport_driver_probe(struct device *dev)
685 {
686 struct gameport *gameport = to_gameport_port(dev);
687 struct gameport_driver *drv = to_gameport_driver(dev->driver);
688
689 drv->connect(gameport, drv);
690 return gameport->drv ? 0 : -ENODEV;
691 }
692
693 static int gameport_driver_remove(struct device *dev)
694 {
695 struct gameport *gameport = to_gameport_port(dev);
696 struct gameport_driver *drv = to_gameport_driver(dev->driver);
697
698 drv->disconnect(gameport);
699 return 0;
700 }
701
702 static void gameport_attach_driver(struct gameport_driver *drv)
703 {
704 int error;
705
706 error = driver_attach(&drv->driver);
707 if (error)
708 printk(KERN_ERR
709 "gameport: driver_attach() failed for %s, error: %d\n",
710 drv->driver.name, error);
711 }
712
713 int __gameport_register_driver(struct gameport_driver *drv, struct module *owner,
714 const char *mod_name)
715 {
716 int error;
717
718 drv->driver.bus = &gameport_bus;
719 drv->driver.owner = owner;
720 drv->driver.mod_name = mod_name;
721
722 /*
723 * Temporarily disable automatic binding because probing
724 * takes long time and we are better off doing it in kgameportd
725 */
726 drv->ignore = true;
727
728 error = driver_register(&drv->driver);
729 if (error) {
730 printk(KERN_ERR
731 "gameport: driver_register() failed for %s, error: %d\n",
732 drv->driver.name, error);
733 return error;
734 }
735
736 /*
737 * Reset ignore flag and let kgameportd bind the driver to free ports
738 */
739 drv->ignore = false;
740 error = gameport_queue_event(drv, NULL, GAMEPORT_ATTACH_DRIVER);
741 if (error) {
742 driver_unregister(&drv->driver);
743 return error;
744 }
745
746 return 0;
747 }
748 EXPORT_SYMBOL(__gameport_register_driver);
749
750 void gameport_unregister_driver(struct gameport_driver *drv)
751 {
752 struct gameport *gameport;
753
754 mutex_lock(&gameport_mutex);
755
756 drv->ignore = true; /* so gameport_find_driver ignores it */
757 gameport_remove_pending_events(drv);
758
759 start_over:
760 list_for_each_entry(gameport, &gameport_list, node) {
761 if (gameport->drv == drv) {
762 gameport_disconnect_port(gameport);
763 gameport_find_driver(gameport);
764 /* we could've deleted some ports, restart */
765 goto start_over;
766 }
767 }
768
769 driver_unregister(&drv->driver);
770
771 mutex_unlock(&gameport_mutex);
772 }
773 EXPORT_SYMBOL(gameport_unregister_driver);
774
775 static int gameport_bus_match(struct device *dev, struct device_driver *drv)
776 {
777 struct gameport_driver *gameport_drv = to_gameport_driver(drv);
778
779 return !gameport_drv->ignore;
780 }
781
782 static struct bus_type gameport_bus = {
783 .name = "gameport",
784 .dev_attrs = gameport_device_attrs,
785 .drv_attrs = gameport_driver_attrs,
786 .match = gameport_bus_match,
787 .probe = gameport_driver_probe,
788 .remove = gameport_driver_remove,
789 };
790
791 static void gameport_set_drv(struct gameport *gameport, struct gameport_driver *drv)
792 {
793 mutex_lock(&gameport->drv_mutex);
794 gameport->drv = drv;
795 mutex_unlock(&gameport->drv_mutex);
796 }
797
798 int gameport_open(struct gameport *gameport, struct gameport_driver *drv, int mode)
799 {
800 if (gameport->open) {
801 if (gameport->open(gameport, mode)) {
802 return -1;
803 }
804 } else {
805 if (mode != GAMEPORT_MODE_RAW)
806 return -1;
807 }
808
809 gameport_set_drv(gameport, drv);
810 return 0;
811 }
812 EXPORT_SYMBOL(gameport_open);
813
814 void gameport_close(struct gameport *gameport)
815 {
816 del_timer_sync(&gameport->poll_timer);
817 gameport->poll_handler = NULL;
818 gameport->poll_interval = 0;
819 gameport_set_drv(gameport, NULL);
820 if (gameport->close)
821 gameport->close(gameport);
822 }
823 EXPORT_SYMBOL(gameport_close);
824
825 static int __init gameport_init(void)
826 {
827 int error;
828
829 error = bus_register(&gameport_bus);
830 if (error) {
831 printk(KERN_ERR "gameport: failed to register gameport bus, error: %d\n", error);
832 return error;
833 }
834
835 gameport_task = kthread_run(gameport_thread, NULL, "kgameportd");
836 if (IS_ERR(gameport_task)) {
837 bus_unregister(&gameport_bus);
838 error = PTR_ERR(gameport_task);
839 printk(KERN_ERR "gameport: Failed to start kgameportd, error: %d\n", error);
840 return error;
841 }
842
843 return 0;
844 }
845
846 static void __exit gameport_exit(void)
847 {
848 bus_unregister(&gameport_bus);
849 kthread_stop(gameport_task);
850 }
851
852 subsys_initcall(gameport_init);
853 module_exit(gameport_exit);
854
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