1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Generic gameport layer
4 *
5 * Copyright (c) 1999-2002 Vojtech Pavlik
6 * Copyright (c) 2005 Dmitry Torokhov
7 */
8
9
10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11
12#include <linux/stddef.h>
13#include <linux/module.h>
14#include <linux/io.h>
15#include <linux/ioport.h>
16#include <linux/init.h>
17#include <linux/gameport.h>
18#include <linux/slab.h>
19#include <linux/delay.h>
20#include <linux/workqueue.h>
21#include <linux/sched.h> /* HZ */
22#include <linux/mutex.h>
23#include <linux/timekeeping.h>
24
25MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
26MODULE_DESCRIPTION("Generic gameport layer");
27MODULE_LICENSE("GPL");
28
29static bool use_ktime = true;
30module_param(use_ktime, bool, 0400);
31MODULE_PARM_DESC(use_ktime, "Use ktime for measuring I/O speed");
32
33/*
34 * gameport_mutex protects entire gameport subsystem and is taken
35 * every time gameport port or driver registrered or unregistered.
36 */
37static DEFINE_MUTEX(gameport_mutex);
38
39static LIST_HEAD(gameport_list);
40
41static struct bus_type gameport_bus;
42
43static void gameport_add_port(struct gameport *gameport);
44static void gameport_attach_driver(struct gameport_driver *drv);
45static void gameport_reconnect_port(struct gameport *gameport);
46static 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
55static 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
77static int gameport_measure_speed(struct gameport *gameport)
78{
79 unsigned int i, t, tx;
80 u64 t1, t2, t3;
81 unsigned long flags;
82
83 if (gameport_open(gameport, NULL, GAMEPORT_MODE_RAW))
84 return 0;
85
86 tx = ~0;
87
88 for (i = 0; i < 50; i++) {
89 local_irq_save(flags);
90 t1 = ktime_get_ns();
91 for (t = 0; t < 50; t++)
92 gameport_read(gameport);
93 t2 = ktime_get_ns();
94 t3 = ktime_get_ns();
95 local_irq_restore(flags);
96 udelay(i * 10);
97 t = (t2 - t1) - (t3 - t2);
98 if (t < tx)
99 tx = t;
100 }
101
102 gameport_close(gameport);
103 t = 1000000 * 50;
104 if (tx)
105 t /= tx;
106 return t;
107}
108
109static int old_gameport_measure_speed(struct gameport *gameport)
110{
111#if defined(__i386__)
112
113 unsigned int i, t, t1, t2, t3, tx;
114 unsigned long flags;
115
116 if (gameport_open(gameport, NULL, GAMEPORT_MODE_RAW))
117 return 0;
118
119 tx = 1 << 30;
120
121 for(i = 0; i < 50; i++) {
122 local_irq_save(flags);
123 GET_TIME(t1);
124 for (t = 0; t < 50; t++) gameport_read(gameport);
125 GET_TIME(t2);
126 GET_TIME(t3);
127 local_irq_restore(flags);
128 udelay(i * 10);
129 if ((t = DELTA(t2,t1) - DELTA(t3,t2)) < tx) tx = t;
130 }
131
132 gameport_close(gameport);
133 return 59659 / (tx < 1 ? 1 : tx);
134
135#elif defined (__x86_64__)
136
137 unsigned int i, t;
138 unsigned long tx, t1, t2, flags;
139
140 if (gameport_open(gameport, NULL, GAMEPORT_MODE_RAW))
141 return 0;
142
143 tx = 1 << 30;
144
145 for(i = 0; i < 50; i++) {
146 local_irq_save(flags);
147 t1 = rdtsc();
148 for (t = 0; t < 50; t++) gameport_read(gameport);
149 t2 = rdtsc();
150 local_irq_restore(flags);
151 udelay(i * 10);
152 if (t2 - t1 < tx) tx = t2 - t1;
153 }
154
155 gameport_close(gameport);
156 return (this_cpu_read(cpu_info.loops_per_jiffy) *
157 (unsigned long)HZ / (1000 / 50)) / (tx < 1 ? 1 : tx);
158
159#else
160
161 unsigned int j, t = 0;
162
163 if (gameport_open(gameport, NULL, GAMEPORT_MODE_RAW))
164 return 0;
165
166 j = jiffies; while (j == jiffies);
167 j = jiffies; while (j == jiffies) { t++; gameport_read(gameport); }
168
169 gameport_close(gameport);
170 return t * HZ / 1000;
171
172#endif
173}
174
175void gameport_start_polling(struct gameport *gameport)
176{
177 spin_lock(lock: &gameport->timer_lock);
178
179 if (!gameport->poll_cnt++) {
180 BUG_ON(!gameport->poll_handler);
181 BUG_ON(!gameport->poll_interval);
182 mod_timer(timer: &gameport->poll_timer, expires: jiffies + msecs_to_jiffies(m: gameport->poll_interval));
183 }
184
185 spin_unlock(lock: &gameport->timer_lock);
186}
187EXPORT_SYMBOL(gameport_start_polling);
188
189void gameport_stop_polling(struct gameport *gameport)
190{
191 spin_lock(lock: &gameport->timer_lock);
192
193 if (!--gameport->poll_cnt)
194 del_timer(timer: &gameport->poll_timer);
195
196 spin_unlock(lock: &gameport->timer_lock);
197}
198EXPORT_SYMBOL(gameport_stop_polling);
199
200static void gameport_run_poll_handler(struct timer_list *t)
201{
202 struct gameport *gameport = from_timer(gameport, t, poll_timer);
203
204 gameport->poll_handler(gameport);
205 if (gameport->poll_cnt)
206 mod_timer(timer: &gameport->poll_timer, expires: jiffies + msecs_to_jiffies(m: gameport->poll_interval));
207}
208
209/*
210 * Basic gameport -> driver core mappings
211 */
212
213static int gameport_bind_driver(struct gameport *gameport, struct gameport_driver *drv)
214{
215 int error;
216
217 gameport->dev.driver = &drv->driver;
218 if (drv->connect(gameport, drv)) {
219 gameport->dev.driver = NULL;
220 return -ENODEV;
221 }
222
223 error = device_bind_driver(dev: &gameport->dev);
224 if (error) {
225 dev_warn(&gameport->dev,
226 "device_bind_driver() failed for %s (%s) and %s, error: %d\n",
227 gameport->phys, gameport->name,
228 drv->description, error);
229 drv->disconnect(gameport);
230 gameport->dev.driver = NULL;
231 return error;
232 }
233
234 return 0;
235}
236
237static void gameport_find_driver(struct gameport *gameport)
238{
239 int error;
240
241 error = device_attach(dev: &gameport->dev);
242 if (error < 0)
243 dev_warn(&gameport->dev,
244 "device_attach() failed for %s (%s), error: %d\n",
245 gameport->phys, gameport->name, error);
246}
247
248
249/*
250 * Gameport event processing.
251 */
252
253enum gameport_event_type {
254 GAMEPORT_REGISTER_PORT,
255 GAMEPORT_ATTACH_DRIVER,
256};
257
258struct gameport_event {
259 enum gameport_event_type type;
260 void *object;
261 struct module *owner;
262 struct list_head node;
263};
264
265static DEFINE_SPINLOCK(gameport_event_lock); /* protects gameport_event_list */
266static LIST_HEAD(gameport_event_list);
267
268static struct gameport_event *gameport_get_event(void)
269{
270 struct gameport_event *event = NULL;
271 unsigned long flags;
272
273 spin_lock_irqsave(&gameport_event_lock, flags);
274
275 if (!list_empty(head: &gameport_event_list)) {
276 event = list_first_entry(&gameport_event_list,
277 struct gameport_event, node);
278 list_del_init(entry: &event->node);
279 }
280
281 spin_unlock_irqrestore(lock: &gameport_event_lock, flags);
282 return event;
283}
284
285static void gameport_free_event(struct gameport_event *event)
286{
287 module_put(module: event->owner);
288 kfree(objp: event);
289}
290
291static void gameport_remove_duplicate_events(struct gameport_event *event)
292{
293 struct gameport_event *e, *next;
294 unsigned long flags;
295
296 spin_lock_irqsave(&gameport_event_lock, flags);
297
298 list_for_each_entry_safe(e, next, &gameport_event_list, node) {
299 if (event->object == e->object) {
300 /*
301 * If this event is of different type we should not
302 * look further - we only suppress duplicate events
303 * that were sent back-to-back.
304 */
305 if (event->type != e->type)
306 break;
307
308 list_del_init(entry: &e->node);
309 gameport_free_event(event: e);
310 }
311 }
312
313 spin_unlock_irqrestore(lock: &gameport_event_lock, flags);
314}
315
316
317static void gameport_handle_events(struct work_struct *work)
318{
319 struct gameport_event *event;
320
321 mutex_lock(&gameport_mutex);
322
323 /*
324 * Note that we handle only one event here to give swsusp
325 * a chance to freeze kgameportd thread. Gameport events
326 * should be pretty rare so we are not concerned about
327 * taking performance hit.
328 */
329 if ((event = gameport_get_event())) {
330
331 switch (event->type) {
332
333 case GAMEPORT_REGISTER_PORT:
334 gameport_add_port(gameport: event->object);
335 break;
336
337 case GAMEPORT_ATTACH_DRIVER:
338 gameport_attach_driver(drv: event->object);
339 break;
340 }
341
342 gameport_remove_duplicate_events(event);
343 gameport_free_event(event);
344 }
345
346 mutex_unlock(lock: &gameport_mutex);
347}
348
349static DECLARE_WORK(gameport_event_work, gameport_handle_events);
350
351static int gameport_queue_event(void *object, struct module *owner,
352 enum gameport_event_type event_type)
353{
354 unsigned long flags;
355 struct gameport_event *event;
356 int retval = 0;
357
358 spin_lock_irqsave(&gameport_event_lock, flags);
359
360 /*
361 * Scan event list for the other events for the same gameport port,
362 * starting with the most recent one. If event is the same we
363 * do not need add new one. If event is of different type we
364 * need to add this event and should not look further because
365 * we need to preserve sequence of distinct events.
366 */
367 list_for_each_entry_reverse(event, &gameport_event_list, node) {
368 if (event->object == object) {
369 if (event->type == event_type)
370 goto out;
371 break;
372 }
373 }
374
375 event = kmalloc(size: sizeof(struct gameport_event), GFP_ATOMIC);
376 if (!event) {
377 pr_err("Not enough memory to queue event %d\n", event_type);
378 retval = -ENOMEM;
379 goto out;
380 }
381
382 if (!try_module_get(module: owner)) {
383 pr_warn("Can't get module reference, dropping event %d\n",
384 event_type);
385 kfree(objp: event);
386 retval = -EINVAL;
387 goto out;
388 }
389
390 event->type = event_type;
391 event->object = object;
392 event->owner = owner;
393
394 list_add_tail(new: &event->node, head: &gameport_event_list);
395 queue_work(wq: system_long_wq, work: &gameport_event_work);
396
397out:
398 spin_unlock_irqrestore(lock: &gameport_event_lock, flags);
399 return retval;
400}
401
402/*
403 * Remove all events that have been submitted for a given object,
404 * be it a gameport port or a driver.
405 */
406static void gameport_remove_pending_events(void *object)
407{
408 struct gameport_event *event, *next;
409 unsigned long flags;
410
411 spin_lock_irqsave(&gameport_event_lock, flags);
412
413 list_for_each_entry_safe(event, next, &gameport_event_list, node) {
414 if (event->object == object) {
415 list_del_init(entry: &event->node);
416 gameport_free_event(event);
417 }
418 }
419
420 spin_unlock_irqrestore(lock: &gameport_event_lock, flags);
421}
422
423/*
424 * Destroy child gameport port (if any) that has not been fully registered yet.
425 *
426 * Note that we rely on the fact that port can have only one child and therefore
427 * only one child registration request can be pending. Additionally, children
428 * are registered by driver's connect() handler so there can't be a grandchild
429 * pending registration together with a child.
430 */
431static struct gameport *gameport_get_pending_child(struct gameport *parent)
432{
433 struct gameport_event *event;
434 struct gameport *gameport, *child = NULL;
435 unsigned long flags;
436
437 spin_lock_irqsave(&gameport_event_lock, flags);
438
439 list_for_each_entry(event, &gameport_event_list, node) {
440 if (event->type == GAMEPORT_REGISTER_PORT) {
441 gameport = event->object;
442 if (gameport->parent == parent) {
443 child = gameport;
444 break;
445 }
446 }
447 }
448
449 spin_unlock_irqrestore(lock: &gameport_event_lock, flags);
450 return child;
451}
452
453/*
454 * Gameport port operations
455 */
456
457static ssize_t gameport_description_show(struct device *dev, struct device_attribute *attr, char *buf)
458{
459 struct gameport *gameport = to_gameport_port(dev);
460
461 return sprintf(buf, fmt: "%s\n", gameport->name);
462}
463static DEVICE_ATTR(description, S_IRUGO, gameport_description_show, NULL);
464
465static ssize_t drvctl_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
466{
467 struct gameport *gameport = to_gameport_port(dev);
468 struct device_driver *drv;
469 int error;
470
471 error = mutex_lock_interruptible(&gameport_mutex);
472 if (error)
473 return error;
474
475 if (!strncmp(buf, "none", count)) {
476 gameport_disconnect_port(gameport);
477 } else if (!strncmp(buf, "reconnect", count)) {
478 gameport_reconnect_port(gameport);
479 } else if (!strncmp(buf, "rescan", count)) {
480 gameport_disconnect_port(gameport);
481 gameport_find_driver(gameport);
482 } else if ((drv = driver_find(name: buf, bus: &gameport_bus)) != NULL) {
483 gameport_disconnect_port(gameport);
484 error = gameport_bind_driver(gameport, to_gameport_driver(drv));
485 } else {
486 error = -EINVAL;
487 }
488
489 mutex_unlock(lock: &gameport_mutex);
490
491 return error ? error : count;
492}
493static DEVICE_ATTR_WO(drvctl);
494
495static struct attribute *gameport_device_attrs[] = {
496 &dev_attr_description.attr,
497 &dev_attr_drvctl.attr,
498 NULL,
499};
500ATTRIBUTE_GROUPS(gameport_device);
501
502static void gameport_release_port(struct device *dev)
503{
504 struct gameport *gameport = to_gameport_port(dev);
505
506 kfree(objp: gameport);
507 module_put(THIS_MODULE);
508}
509
510void gameport_set_phys(struct gameport *gameport, const char *fmt, ...)
511{
512 va_list args;
513
514 va_start(args, fmt);
515 vsnprintf(buf: gameport->phys, size: sizeof(gameport->phys), fmt, args);
516 va_end(args);
517}
518EXPORT_SYMBOL(gameport_set_phys);
519
520static void gameport_default_trigger(struct gameport *gameport)
521{
522#ifdef CONFIG_HAS_IOPORT
523 outb(value: 0xff, port: gameport->io);
524#endif
525}
526
527static unsigned char gameport_default_read(struct gameport *gameport)
528{
529#ifdef CONFIG_HAS_IOPORT
530 return inb(port: gameport->io);
531#else
532 return 0xff;
533#endif
534}
535
536static void gameport_setup_default_handlers(struct gameport *gameport)
537{
538 if ((!gameport->trigger || !gameport->read) &&
539 !IS_ENABLED(CONFIG_HAS_IOPORT))
540 dev_err(&gameport->dev,
541 "I/O port access is required for %s (%s) but is not available\n",
542 gameport->phys, gameport->name);
543
544 if (!gameport->trigger)
545 gameport->trigger = gameport_default_trigger;
546 if (!gameport->read)
547 gameport->read = gameport_default_read;
548}
549
550/*
551 * Prepare gameport port for registration.
552 */
553static void gameport_init_port(struct gameport *gameport)
554{
555 static atomic_t gameport_no = ATOMIC_INIT(-1);
556
557 __module_get(THIS_MODULE);
558
559 mutex_init(&gameport->drv_mutex);
560 device_initialize(dev: &gameport->dev);
561 dev_set_name(dev: &gameport->dev, name: "gameport%lu",
562 (unsigned long)atomic_inc_return(v: &gameport_no));
563 gameport->dev.bus = &gameport_bus;
564 gameport->dev.release = gameport_release_port;
565 if (gameport->parent)
566 gameport->dev.parent = &gameport->parent->dev;
567
568 gameport_setup_default_handlers(gameport);
569 INIT_LIST_HEAD(list: &gameport->node);
570 spin_lock_init(&gameport->timer_lock);
571 timer_setup(&gameport->poll_timer, gameport_run_poll_handler, 0);
572}
573
574/*
575 * Complete gameport port registration.
576 * Driver core will attempt to find appropriate driver for the port.
577 */
578static void gameport_add_port(struct gameport *gameport)
579{
580 int error;
581
582 if (gameport->parent)
583 gameport->parent->child = gameport;
584
585 gameport->speed = use_ktime ?
586 gameport_measure_speed(gameport) :
587 old_gameport_measure_speed(gameport);
588
589 list_add_tail(new: &gameport->node, head: &gameport_list);
590
591 if (gameport->io)
592 dev_info(&gameport->dev, "%s is %s, io %#x, speed %dkHz\n",
593 gameport->name, gameport->phys, gameport->io, gameport->speed);
594 else
595 dev_info(&gameport->dev, "%s is %s, speed %dkHz\n",
596 gameport->name, gameport->phys, gameport->speed);
597
598 error = device_add(dev: &gameport->dev);
599 if (error)
600 dev_err(&gameport->dev,
601 "device_add() failed for %s (%s), error: %d\n",
602 gameport->phys, gameport->name, error);
603}
604
605/*
606 * gameport_destroy_port() completes deregistration process and removes
607 * port from the system
608 */
609static void gameport_destroy_port(struct gameport *gameport)
610{
611 struct gameport *child;
612
613 child = gameport_get_pending_child(parent: gameport);
614 if (child) {
615 gameport_remove_pending_events(object: child);
616 put_device(dev: &child->dev);
617 }
618
619 if (gameport->parent) {
620 gameport->parent->child = NULL;
621 gameport->parent = NULL;
622 }
623
624 if (device_is_registered(dev: &gameport->dev))
625 device_del(dev: &gameport->dev);
626
627 list_del_init(entry: &gameport->node);
628
629 gameport_remove_pending_events(object: gameport);
630 put_device(dev: &gameport->dev);
631}
632
633/*
634 * Reconnect gameport port and all its children (re-initialize attached devices)
635 */
636static void gameport_reconnect_port(struct gameport *gameport)
637{
638 do {
639 if (!gameport->drv || !gameport->drv->reconnect || gameport->drv->reconnect(gameport)) {
640 gameport_disconnect_port(gameport);
641 gameport_find_driver(gameport);
642 /* Ok, old children are now gone, we are done */
643 break;
644 }
645 gameport = gameport->child;
646 } while (gameport);
647}
648
649/*
650 * gameport_disconnect_port() unbinds a port from its driver. As a side effect
651 * all child ports are unbound and destroyed.
652 */
653static void gameport_disconnect_port(struct gameport *gameport)
654{
655 struct gameport *s, *parent;
656
657 if (gameport->child) {
658 /*
659 * Children ports should be disconnected and destroyed
660 * first, staring with the leaf one, since we don't want
661 * to do recursion
662 */
663 for (s = gameport; s->child; s = s->child)
664 /* empty */;
665
666 do {
667 parent = s->parent;
668
669 device_release_driver(dev: &s->dev);
670 gameport_destroy_port(gameport: s);
671 } while ((s = parent) != gameport);
672 }
673
674 /*
675 * Ok, no children left, now disconnect this port
676 */
677 device_release_driver(dev: &gameport->dev);
678}
679
680/*
681 * Submits register request to kgameportd for subsequent execution.
682 * Note that port registration is always asynchronous.
683 */
684void __gameport_register_port(struct gameport *gameport, struct module *owner)
685{
686 gameport_init_port(gameport);
687 gameport_queue_event(object: gameport, owner, event_type: GAMEPORT_REGISTER_PORT);
688}
689EXPORT_SYMBOL(__gameport_register_port);
690
691/*
692 * Synchronously unregisters gameport port.
693 */
694void gameport_unregister_port(struct gameport *gameport)
695{
696 mutex_lock(&gameport_mutex);
697 gameport_disconnect_port(gameport);
698 gameport_destroy_port(gameport);
699 mutex_unlock(lock: &gameport_mutex);
700}
701EXPORT_SYMBOL(gameport_unregister_port);
702
703
704/*
705 * Gameport driver operations
706 */
707
708static ssize_t description_show(struct device_driver *drv, char *buf)
709{
710 struct gameport_driver *driver = to_gameport_driver(drv);
711 return sprintf(buf, fmt: "%s\n", driver->description ? driver->description : "(none)");
712}
713static DRIVER_ATTR_RO(description);
714
715static struct attribute *gameport_driver_attrs[] = {
716 &driver_attr_description.attr,
717 NULL
718};
719ATTRIBUTE_GROUPS(gameport_driver);
720
721static int gameport_driver_probe(struct device *dev)
722{
723 struct gameport *gameport = to_gameport_port(dev);
724 struct gameport_driver *drv = to_gameport_driver(dev->driver);
725
726 drv->connect(gameport, drv);
727 return gameport->drv ? 0 : -ENODEV;
728}
729
730static void gameport_driver_remove(struct device *dev)
731{
732 struct gameport *gameport = to_gameport_port(dev);
733 struct gameport_driver *drv = to_gameport_driver(dev->driver);
734
735 drv->disconnect(gameport);
736}
737
738static void gameport_attach_driver(struct gameport_driver *drv)
739{
740 int error;
741
742 error = driver_attach(drv: &drv->driver);
743 if (error)
744 pr_err("driver_attach() failed for %s, error: %d\n",
745 drv->driver.name, error);
746}
747
748int __gameport_register_driver(struct gameport_driver *drv, struct module *owner,
749 const char *mod_name)
750{
751 int error;
752
753 drv->driver.bus = &gameport_bus;
754 drv->driver.owner = owner;
755 drv->driver.mod_name = mod_name;
756
757 /*
758 * Temporarily disable automatic binding because probing
759 * takes long time and we are better off doing it in kgameportd
760 */
761 drv->ignore = true;
762
763 error = driver_register(drv: &drv->driver);
764 if (error) {
765 pr_err("driver_register() failed for %s, error: %d\n",
766 drv->driver.name, error);
767 return error;
768 }
769
770 /*
771 * Reset ignore flag and let kgameportd bind the driver to free ports
772 */
773 drv->ignore = false;
774 error = gameport_queue_event(object: drv, NULL, event_type: GAMEPORT_ATTACH_DRIVER);
775 if (error) {
776 driver_unregister(drv: &drv->driver);
777 return error;
778 }
779
780 return 0;
781}
782EXPORT_SYMBOL(__gameport_register_driver);
783
784void gameport_unregister_driver(struct gameport_driver *drv)
785{
786 struct gameport *gameport;
787
788 mutex_lock(&gameport_mutex);
789
790 drv->ignore = true; /* so gameport_find_driver ignores it */
791 gameport_remove_pending_events(object: drv);
792
793start_over:
794 list_for_each_entry(gameport, &gameport_list, node) {
795 if (gameport->drv == drv) {
796 gameport_disconnect_port(gameport);
797 gameport_find_driver(gameport);
798 /* we could've deleted some ports, restart */
799 goto start_over;
800 }
801 }
802
803 driver_unregister(drv: &drv->driver);
804
805 mutex_unlock(lock: &gameport_mutex);
806}
807EXPORT_SYMBOL(gameport_unregister_driver);
808
809static int gameport_bus_match(struct device *dev, struct device_driver *drv)
810{
811 struct gameport_driver *gameport_drv = to_gameport_driver(drv);
812
813 return !gameport_drv->ignore;
814}
815
816static struct bus_type gameport_bus = {
817 .name = "gameport",
818 .dev_groups = gameport_device_groups,
819 .drv_groups = gameport_driver_groups,
820 .match = gameport_bus_match,
821 .probe = gameport_driver_probe,
822 .remove = gameport_driver_remove,
823};
824
825static void gameport_set_drv(struct gameport *gameport, struct gameport_driver *drv)
826{
827 mutex_lock(&gameport->drv_mutex);
828 gameport->drv = drv;
829 mutex_unlock(lock: &gameport->drv_mutex);
830}
831
832int gameport_open(struct gameport *gameport, struct gameport_driver *drv, int mode)
833{
834 if (gameport->open) {
835 if (gameport->open(gameport, mode)) {
836 return -1;
837 }
838 } else {
839 if (mode != GAMEPORT_MODE_RAW)
840 return -1;
841 }
842
843 gameport_set_drv(gameport, drv);
844 return 0;
845}
846EXPORT_SYMBOL(gameport_open);
847
848void gameport_close(struct gameport *gameport)
849{
850 del_timer_sync(timer: &gameport->poll_timer);
851 gameport->poll_handler = NULL;
852 gameport->poll_interval = 0;
853 gameport_set_drv(gameport, NULL);
854 if (gameport->close)
855 gameport->close(gameport);
856}
857EXPORT_SYMBOL(gameport_close);
858
859static int __init gameport_init(void)
860{
861 int error;
862
863 error = bus_register(bus: &gameport_bus);
864 if (error) {
865 pr_err("failed to register gameport bus, error: %d\n", error);
866 return error;
867 }
868
869
870 return 0;
871}
872
873static void __exit gameport_exit(void)
874{
875 bus_unregister(bus: &gameport_bus);
876
877 /*
878 * There should not be any outstanding events but work may
879 * still be scheduled so simply cancel it.
880 */
881 cancel_work_sync(work: &gameport_event_work);
882}
883
884subsys_initcall(gameport_init);
885module_exit(gameport_exit);
886

source code of linux/drivers/input/gameport/gameport.c