drivers/input/gameport/gameport.c

   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/ioport.h>
  15 #include <linux/init.h>
  16 #include <linux/gameport.h>
  17 #include <linux/slab.h>
  18 #include <linux/delay.h>
  19 #include <linux/workqueue.h>
  20 #include <linux/sched.h>        /* HZ */
  21 #include <linux/mutex.h>
  22 #include <linux/timekeeping.h>
  23
  24 /*#include <asm/io.h>*/
  25
  26 MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
  27 MODULE_DESCRIPTION("Generic gameport layer");
  28 MODULE_LICENSE("GPL");
  29
  30 static bool use_ktime = true;
  31 module_param(use_ktime, bool, 0400);
  32 MODULE_PARM_DESC(use_ktime, "Use ktime for measuring I/O speed");
  33
  34 /*
  35  * gameport_mutex protects entire gameport subsystem and is taken
  36  * every time gameport port or driver registrered or unregistered.
  37  */
  38 static DEFINE_MUTEX(gameport_mutex);
  39
  40 static LIST_HEAD(gameport_list);
  41
  42 static struct bus_type gameport_bus;
  43
  44 static void gameport_add_port(struct gameport *gameport);
  45 static void gameport_attach_driver(struct gameport_driver *drv);
  46 static void gameport_reconnect_port(struct gameport *gameport);
  47 static void gameport_disconnect_port(struct gameport *gameport);
  48
  49 #if defined(__i386__)
  50
  51 #include <linux/i8253.h>
  52
  53 #define DELTA(x,y)      ((y)-(x)+((y)<(x)?1193182/HZ:0))
  54 #define GET_TIME(x)     do { x = get_time_pit(); } while (0)
  55
  56 static unsigned int get_time_pit(void)
  57 {
  58         unsigned long flags;
  59         unsigned int count;
  60
  61         raw_spin_lock_irqsave(&i8253_lock, flags);
  62         outb_p(0x00, 0x43);
  63         count = inb_p(0x40);
  64         count |= inb_p(0x40) << 8;
  65         raw_spin_unlock_irqrestore(&i8253_lock, flags);
  66
  67         return count;
  68 }
  69
  70 #endif
  71
  72
  73
  74 /*
  75  * gameport_measure_speed() measures the gameport i/o speed.
  76  */
  77
  78 static int gameport_measure_speed(struct gameport *gameport)
  79 {
  80         unsigned int i, t, tx;
  81         u64 t1, t2, t3;
  82         unsigned long flags;
  83
  84         if (gameport_open(gameport, NULL, GAMEPORT_MODE_RAW))
  85                 return 0;
  86
  87         tx = ~0;
  88
  89         for (i = 0; i < 50; i++) {
  90                 local_irq_save(flags);
  91                 t1 = ktime_get_ns();
  92                 for (t = 0; t < 50; t++)
  93                         gameport_read(gameport);
  94                 t2 = ktime_get_ns();
  95                 t3 = ktime_get_ns();
  96                 local_irq_restore(flags);
  97                 udelay(i * 10);
  98                 t = (t2 - t1) - (t3 - t2);
  99                 if (t < tx)
 100                         tx = t;
 101         }
 102
 103         gameport_close(gameport);
 104         t = 1000000 * 50;
 105         if (tx)
 106                 t /= tx;
 107         return t;
 108 }
 109
 110 static int old_gameport_measure_speed(struct gameport *gameport)
 111 {
 112 #if defined(__i386__)
 113
 114         unsigned int i, t, t1, t2, t3, tx;
 115         unsigned long flags;
 116
 117         if (gameport_open(gameport, NULL, GAMEPORT_MODE_RAW))
 118                 return 0;
 119
 120         tx = 1 << 30;
 121
 122         for(i = 0; i < 50; i++) {
 123                 local_irq_save(flags);
 124                 GET_TIME(t1);
 125                 for (t = 0; t < 50; t++) gameport_read(gameport);
 126                 GET_TIME(t2);
 127                 GET_TIME(t3);
 128                 local_irq_restore(flags);
 129                 udelay(i * 10);
 130                 if ((t = DELTA(t2,t1) - DELTA(t3,t2)) < tx) tx = t;
 131         }
 132
 133         gameport_close(gameport);
 134         return 59659 / (tx < 1 ? 1 : tx);
 135
 136 #elif defined (__x86_64__)
 137
 138         unsigned int i, t;
 139         unsigned long tx, t1, t2, flags;
 140
 141         if (gameport_open(gameport, NULL, GAMEPORT_MODE_RAW))
 142                 return 0;
 143
 144         tx = 1 << 30;
 145
 146         for(i = 0; i < 50; i++) {
 147                 local_irq_save(flags);
 148                 t1 = rdtsc();
 149                 for (t = 0; t < 50; t++) gameport_read(gameport);
 150                 t2 = rdtsc();
 151                 local_irq_restore(flags);
 152                 udelay(i * 10);
 153                 if (t2 - t1 < tx) tx = t2 - t1;
 154         }
 155
 156         gameport_close(gameport);
 157         return (this_cpu_read(cpu_info.loops_per_jiffy) *
 158                 (unsigned long)HZ / (1000 / 50)) / (tx < 1 ? 1 : tx);
 159
 160 #else
 161
 162         unsigned int j, t = 0;
 163
 164         if (gameport_open(gameport, NULL, GAMEPORT_MODE_RAW))
 165                 return 0;
 166
 167         j = jiffies; while (j == jiffies);
 168         j = jiffies; while (j == jiffies) { t++; gameport_read(gameport); }
 169
 170         gameport_close(gameport);
 171         return t * HZ / 1000;
 172
 173 #endif
 174 }
 175
 176 void gameport_start_polling(struct gameport *gameport)
 177 {
 178         spin_lock(&gameport->timer_lock);
 179
 180         if (!gameport->poll_cnt++) {
 181                 BUG_ON(!gameport->poll_handler);
 182                 BUG_ON(!gameport->poll_interval);
 183                 mod_timer(&gameport->poll_timer, jiffies + msecs_to_jiffies(gameport->poll_interval));
 184         }
 185
 186         spin_unlock(&gameport->timer_lock);
 187 }
 188 EXPORT_SYMBOL(gameport_start_polling);
 189
 190 void gameport_stop_polling(struct gameport *gameport)
 191 {
 192         spin_lock(&gameport->timer_lock);
 193
 194         if (!--gameport->poll_cnt)
 195                 del_timer(&gameport->poll_timer);
 196
 197         spin_unlock(&gameport->timer_lock);
 198 }
 199 EXPORT_SYMBOL(gameport_stop_polling);
 200
 201 static void gameport_run_poll_handler(struct timer_list *t)
 202 {
 203         struct gameport *gameport = from_timer(gameport, t, poll_timer);
 204
 205         gameport->poll_handler(gameport);
 206         if (gameport->poll_cnt)
 207                 mod_timer(&gameport->poll_timer, jiffies + msecs_to_jiffies(gameport->poll_interval));
 208 }
 209
 210 /*
 211  * Basic gameport -> driver core mappings
 212  */
 213
 214 static int gameport_bind_driver(struct gameport *gameport, struct gameport_driver *drv)
 215 {
 216         int error;
 217
 218         gameport->dev.driver = &drv->driver;
 219         if (drv->connect(gameport, drv)) {
 220                 gameport->dev.driver = NULL;
 221                 return -ENODEV;
 222         }
 223
 224         error = device_bind_driver(&gameport->dev);
 225         if (error) {
 226                 dev_warn(&gameport->dev,
 227                          "device_bind_driver() failed for %s (%s) and %s, error: %d\n",
 228                         gameport->phys, gameport->name,
 229                         drv->description, error);
 230                 drv->disconnect(gameport);
 231                 gameport->dev.driver = NULL;
 232                 return error;
 233         }
 234
 235         return 0;
 236 }
 237
 238 static void gameport_find_driver(struct gameport *gameport)
 239 {
 240         int error;
 241
 242         error = device_attach(&gameport->dev);
 243         if (error < 0)
 244                 dev_warn(&gameport->dev,
 245                          "device_attach() failed for %s (%s), error: %d\n",
 246                          gameport->phys, gameport->name, error);
 247 }
 248
 249
 250 /*
 251  * Gameport event processing.
 252  */
 253
 254 enum gameport_event_type {
 255         GAMEPORT_REGISTER_PORT,
 256         GAMEPORT_ATTACH_DRIVER,
 257 };
 258
 259 struct gameport_event {
 260         enum gameport_event_type type;
 261         void *object;
 262         struct module *owner;
 263         struct list_head node;
 264 };
 265
 266 static DEFINE_SPINLOCK(gameport_event_lock);    /* protects gameport_event_list */
 267 static LIST_HEAD(gameport_event_list);
 268
 269 static struct gameport_event *gameport_get_event(void)
 270 {
 271         struct gameport_event *event = NULL;
 272         unsigned long flags;
 273
 274         spin_lock_irqsave(&gameport_event_lock, flags);
 275
 276         if (!list_empty(&gameport_event_list)) {
 277                 event = list_first_entry(&gameport_event_list,
 278                                          struct gameport_event, node);
 279                 list_del_init(&event->node);
 280         }
 281
 282         spin_unlock_irqrestore(&gameport_event_lock, flags);
 283         return event;
 284 }
 285
 286 static void gameport_free_event(struct gameport_event *event)
 287 {
 288         module_put(event->owner);
 289         kfree(event);
 290 }
 291
 292 static void gameport_remove_duplicate_events(struct gameport_event *event)
 293 {
 294         struct gameport_event *e, *next;
 295         unsigned long flags;
 296
 297         spin_lock_irqsave(&gameport_event_lock, flags);
 298
 299         list_for_each_entry_safe(e, next, &gameport_event_list, node) {
 300                 if (event->object == e->object) {
 301                         /*
 302                          * If this event is of different type we should not
 303                          * look further - we only suppress duplicate events
 304                          * that were sent back-to-back.
 305                          */
 306                         if (event->type != e->type)
 307                                 break;
 308
 309                         list_del_init(&e->node);
 310                         gameport_free_event(e);
 311                 }
 312         }
 313
 314         spin_unlock_irqrestore(&gameport_event_lock, flags);
 315 }
 316
 317
 318 static void gameport_handle_events(struct work_struct *work)
 319 {
 320         struct gameport_event *event;
 321
 322         mutex_lock(&gameport_mutex);
 323
 324         /*
 325          * Note that we handle only one event here to give swsusp
 326          * a chance to freeze kgameportd thread. Gameport events
 327          * should be pretty rare so we are not concerned about
 328          * taking performance hit.
 329          */
 330         if ((event = gameport_get_event())) {
 331
 332                 switch (event->type) {
 333
 334                 case GAMEPORT_REGISTER_PORT:
 335                         gameport_add_port(event->object);
 336                         break;
 337
 338                 case GAMEPORT_ATTACH_DRIVER:
 339                         gameport_attach_driver(event->object);
 340                         break;
 341                 }
 342
 343                 gameport_remove_duplicate_events(event);
 344                 gameport_free_event(event);
 345         }
 346
 347         mutex_unlock(&gameport_mutex);
 348 }
 349
 350 static DECLARE_WORK(gameport_event_work, gameport_handle_events);
 351
 352 static int gameport_queue_event(void *object, struct module *owner,
 353                                 enum gameport_event_type event_type)
 354 {
 355         unsigned long flags;
 356         struct gameport_event *event;
 357         int retval = 0;
 358
 359         spin_lock_irqsave(&gameport_event_lock, flags);
 360
 361         /*
 362          * Scan event list for the other events for the same gameport port,
 363          * starting with the most recent one. If event is the same we
 364          * do not need add new one. If event is of different type we
 365          * need to add this event and should not look further because
 366          * we need to preserve sequence of distinct events.
 367          */
 368         list_for_each_entry_reverse(event, &gameport_event_list, node) {
 369                 if (event->object == object) {
 370                         if (event->type == event_type)
 371                                 goto out;
 372                         break;
 373                 }
 374         }
 375
 376         event = kmalloc(sizeof(struct gameport_event), GFP_ATOMIC);
 377         if (!event) {
 378                 pr_err("Not enough memory to queue event %d\n", event_type);
 379                 retval = -ENOMEM;
 380                 goto out;
 381         }
 382
 383         if (!try_module_get(owner)) {
 384                 pr_warn("Can't get module reference, dropping event %d\n",
 385                         event_type);
 386                 kfree(event);
 387                 retval = -EINVAL;
 388                 goto out;
 389         }
 390
 391         event->type = event_type;
 392         event->object = object;
 393         event->owner = owner;
 394
 395         list_add_tail(&event->node, &gameport_event_list);
 396         queue_work(system_long_wq, &gameport_event_work);
 397
 398 out:
 399         spin_unlock_irqrestore(&gameport_event_lock, flags);
 400         return retval;
 401 }
 402
 403 /*
 404  * Remove all events that have been submitted for a given object,
 405  * be it a gameport port or a driver.
 406  */
 407 static void gameport_remove_pending_events(void *object)
 408 {
 409         struct gameport_event *event, *next;
 410         unsigned long flags;
 411
 412         spin_lock_irqsave(&gameport_event_lock, flags);
 413
 414         list_for_each_entry_safe(event, next, &gameport_event_list, node) {
 415                 if (event->object == object) {
 416                         list_del_init(&event->node);
 417                         gameport_free_event(event);
 418                 }
 419         }
 420
 421         spin_unlock_irqrestore(&gameport_event_lock, flags);
 422 }
 423
 424 /*
 425  * Destroy child gameport port (if any) that has not been fully registered yet.
 426  *
 427  * Note that we rely on the fact that port can have only one child and therefore
 428  * only one child registration request can be pending. Additionally, children
 429  * are registered by driver's connect() handler so there can't be a grandchild
 430  * pending registration together with a child.
 431  */
 432 static struct gameport *gameport_get_pending_child(struct gameport *parent)
 433 {
 434         struct gameport_event *event;
 435         struct gameport *gameport, *child = NULL;
 436         unsigned long flags;
 437
 438         spin_lock_irqsave(&gameport_event_lock, flags);
 439
 440         list_for_each_entry(event, &gameport_event_list, node) {
 441                 if (event->type == GAMEPORT_REGISTER_PORT) {
 442                         gameport = event->object;
 443                         if (gameport->parent == parent) {
 444                                 child = gameport;
 445                                 break;
 446                         }
 447                 }
 448         }
 449
 450         spin_unlock_irqrestore(&gameport_event_lock, flags);
 451         return child;
 452 }
 453
 454 /*
 455  * Gameport port operations
 456  */
 457
 458 static ssize_t gameport_description_show(struct device *dev, struct device_attribute *attr, char *buf)
 459 {
 460         struct gameport *gameport = to_gameport_port(dev);
 461
 462         return sprintf(buf, "%s\n", gameport->name);
 463 }
 464 static DEVICE_ATTR(description, S_IRUGO, gameport_description_show, NULL);
 465
 466 static ssize_t drvctl_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 467 {
 468         struct gameport *gameport = to_gameport_port(dev);
 469         struct device_driver *drv;
 470         int error;
 471
 472         error = mutex_lock_interruptible(&gameport_mutex);
 473         if (error)
 474                 return error;
 475
 476         if (!strncmp(buf, "none", count)) {
 477                 gameport_disconnect_port(gameport);
 478         } else if (!strncmp(buf, "reconnect", count)) {
 479                 gameport_reconnect_port(gameport);
 480         } else if (!strncmp(buf, "rescan", count)) {
 481                 gameport_disconnect_port(gameport);
 482                 gameport_find_driver(gameport);
 483         } else if ((drv = driver_find(buf, &gameport_bus)) != NULL) {
 484                 gameport_disconnect_port(gameport);
 485                 error = gameport_bind_driver(gameport, to_gameport_driver(drv));
 486         } else {
 487                 error = -EINVAL;
 488         }
 489
 490         mutex_unlock(&gameport_mutex);
 491
 492         return error ? error : count;
 493 }
 494 static DEVICE_ATTR_WO(drvctl);
 495
 496 static struct attribute *gameport_device_attrs[] = {
 497         &dev_attr_description.attr,
 498         &dev_attr_drvctl.attr,
 499         NULL,
 500 };
 501 ATTRIBUTE_GROUPS(gameport_device);
 502
 503 static void gameport_release_port(struct device *dev)
 504 {
 505         struct gameport *gameport = to_gameport_port(dev);
 506
 507         kfree(gameport);
 508         module_put(THIS_MODULE);
 509 }
 510
 511 void gameport_set_phys(struct gameport *gameport, const char *fmt, ...)
 512 {
 513         va_list args;
 514
 515         va_start(args, fmt);
 516         vsnprintf(gameport->phys, sizeof(gameport->phys), fmt, args);
 517         va_end(args);
 518 }
 519 EXPORT_SYMBOL(gameport_set_phys);
 520
 521 /*
 522  * Prepare gameport port for registration.
 523  */
 524 static void gameport_init_port(struct gameport *gameport)
 525 {
 526         static atomic_t gameport_no = ATOMIC_INIT(-1);
 527
 528         __module_get(THIS_MODULE);
 529
 530         mutex_init(&gameport->drv_mutex);
 531         device_initialize(&gameport->dev);
 532         dev_set_name(&gameport->dev, "gameport%lu",
 533                         (unsigned long)atomic_inc_return(&gameport_no));
 534         gameport->dev.bus = &gameport_bus;
 535         gameport->dev.release = gameport_release_port;
 536         if (gameport->parent)
 537                 gameport->dev.parent = &gameport->parent->dev;
 538
 539         INIT_LIST_HEAD(&gameport->node);
 540         spin_lock_init(&gameport->timer_lock);
 541         timer_setup(&gameport->poll_timer, gameport_run_poll_handler, 0);
 542 }
 543
 544 /*
 545  * Complete gameport port registration.
 546  * Driver core will attempt to find appropriate driver for the port.
 547  */
 548 static void gameport_add_port(struct gameport *gameport)
 549 {
 550         int error;
 551
 552         if (gameport->parent)
 553                 gameport->parent->child = gameport;
 554
 555         gameport->speed = use_ktime ?
 556                 gameport_measure_speed(gameport) :
 557                 old_gameport_measure_speed(gameport);
 558
 559         list_add_tail(&gameport->node, &gameport_list);
 560
 561         if (gameport->io)
 562                 dev_info(&gameport->dev, "%s is %s, io %#x, speed %dkHz\n",
 563                          gameport->name, gameport->phys, gameport->io, gameport->speed);
 564         else
 565                 dev_info(&gameport->dev, "%s is %s, speed %dkHz\n",
 566                         gameport->name, gameport->phys, gameport->speed);
 567
 568         error = device_add(&gameport->dev);
 569         if (error)
 570                 dev_err(&gameport->dev,
 571                         "device_add() failed for %s (%s), error: %d\n",
 572                         gameport->phys, gameport->name, error);
 573 }
 574
 575 /*
 576  * gameport_destroy_port() completes deregistration process and removes
 577  * port from the system
 578  */
 579 static void gameport_destroy_port(struct gameport *gameport)
 580 {
 581         struct gameport *child;
 582
 583         child = gameport_get_pending_child(gameport);
 584         if (child) {
 585                 gameport_remove_pending_events(child);
 586                 put_device(&child->dev);
 587         }
 588
 589         if (gameport->parent) {
 590                 gameport->parent->child = NULL;
 591                 gameport->parent = NULL;
 592         }
 593
 594         if (device_is_registered(&gameport->dev))
 595                 device_del(&gameport->dev);
 596
 597         list_del_init(&gameport->node);
 598
 599         gameport_remove_pending_events(gameport);
 600         put_device(&gameport->dev);
 601 }
 602
 603 /*
 604  * Reconnect gameport port and all its children (re-initialize attached devices)
 605  */
 606 static void gameport_reconnect_port(struct gameport *gameport)
 607 {
 608         do {
 609                 if (!gameport->drv || !gameport->drv->reconnect || gameport->drv->reconnect(gameport)) {
 610                         gameport_disconnect_port(gameport);
 611                         gameport_find_driver(gameport);
 612                         /* Ok, old children are now gone, we are done */
 613                         break;
 614                 }
 615                 gameport = gameport->child;
 616         } while (gameport);
 617 }
 618
 619 /*
 620  * gameport_disconnect_port() unbinds a port from its driver. As a side effect
 621  * all child ports are unbound and destroyed.
 622  */
 623 static void gameport_disconnect_port(struct gameport *gameport)
 624 {
 625         struct gameport *s, *parent;
 626
 627         if (gameport->child) {
 628                 /*
 629                  * Children ports should be disconnected and destroyed
 630                  * first, staring with the leaf one, since we don't want
 631                  * to do recursion
 632                  */
 633                 for (s = gameport; s->child; s = s->child)
 634                         /* empty */;
 635
 636                 do {
 637                         parent = s->parent;
 638
 639                         device_release_driver(&s->dev);
 640                         gameport_destroy_port(s);
 641                 } while ((s = parent) != gameport);
 642         }
 643
 644         /*
 645          * Ok, no children left, now disconnect this port
 646          */
 647         device_release_driver(&gameport->dev);
 648 }
 649
 650 /*
 651  * Submits register request to kgameportd for subsequent execution.
 652  * Note that port registration is always asynchronous.
 653  */
 654 void __gameport_register_port(struct gameport *gameport, struct module *owner)
 655 {
 656         gameport_init_port(gameport);
 657         gameport_queue_event(gameport, owner, GAMEPORT_REGISTER_PORT);
 658 }
 659 EXPORT_SYMBOL(__gameport_register_port);
 660
 661 /*
 662  * Synchronously unregisters gameport port.
 663  */
 664 void gameport_unregister_port(struct gameport *gameport)
 665 {
 666         mutex_lock(&gameport_mutex);
 667         gameport_disconnect_port(gameport);
 668         gameport_destroy_port(gameport);
 669         mutex_unlock(&gameport_mutex);
 670 }
 671 EXPORT_SYMBOL(gameport_unregister_port);
 672
 673
 674 /*
 675  * Gameport driver operations
 676  */
 677
 678 static ssize_t description_show(struct device_driver *drv, char *buf)
 679 {
 680         struct gameport_driver *driver = to_gameport_driver(drv);
 681         return sprintf(buf, "%s\n", driver->description ? driver->description : "(none)");
 682 }
 683 static DRIVER_ATTR_RO(description);
 684
 685 static struct attribute *gameport_driver_attrs[] = {
 686         &driver_attr_description.attr,
 687         NULL
 688 };
 689 ATTRIBUTE_GROUPS(gameport_driver);
 690
 691 static int gameport_driver_probe(struct device *dev)
 692 {
 693         struct gameport *gameport = to_gameport_port(dev);
 694         struct gameport_driver *drv = to_gameport_driver(dev->driver);
 695
 696         drv->connect(gameport, drv);
 697         return gameport->drv ? 0 : -ENODEV;
 698 }
 699
 700 static void gameport_driver_remove(struct device *dev)
 701 {
 702         struct gameport *gameport = to_gameport_port(dev);
 703         struct gameport_driver *drv = to_gameport_driver(dev->driver);
 704
 705         drv->disconnect(gameport);
 706 }
 707
 708 static void gameport_attach_driver(struct gameport_driver *drv)
 709 {
 710         int error;
 711
 712         error = driver_attach(&drv->driver);
 713         if (error)
 714                 pr_err("driver_attach() failed for %s, error: %d\n",
 715                         drv->driver.name, error);
 716 }
 717
 718 int __gameport_register_driver(struct gameport_driver *drv, struct module *owner,
 719                                 const char *mod_name)
 720 {
 721         int error;
 722
 723         drv->driver.bus = &gameport_bus;
 724         drv->driver.owner = owner;
 725         drv->driver.mod_name = mod_name;
 726
 727         /*
 728          * Temporarily disable automatic binding because probing
 729          * takes long time and we are better off doing it in kgameportd
 730          */
 731         drv->ignore = true;
 732
 733         error = driver_register(&drv->driver);
 734         if (error) {
 735                 pr_err("driver_register() failed for %s, error: %d\n",
 736                         drv->driver.name, error);
 737                 return error;
 738         }
 739
 740         /*
 741          * Reset ignore flag and let kgameportd bind the driver to free ports
 742          */
 743         drv->ignore = false;
 744         error = gameport_queue_event(drv, NULL, GAMEPORT_ATTACH_DRIVER);
 745         if (error) {
 746                 driver_unregister(&drv->driver);
 747                 return error;
 748         }
 749
 750         return 0;
 751 }
 752 EXPORT_SYMBOL(__gameport_register_driver);
 753
 754 void gameport_unregister_driver(struct gameport_driver *drv)
 755 {
 756         struct gameport *gameport;
 757
 758         mutex_lock(&gameport_mutex);
 759
 760         drv->ignore = true;     /* so gameport_find_driver ignores it */
 761         gameport_remove_pending_events(drv);
 762
 763 start_over:
 764         list_for_each_entry(gameport, &gameport_list, node) {
 765                 if (gameport->drv == drv) {
 766                         gameport_disconnect_port(gameport);
 767                         gameport_find_driver(gameport);
 768                         /* we could've deleted some ports, restart */
 769                         goto start_over;
 770                 }
 771         }
 772
 773         driver_unregister(&drv->driver);
 774
 775         mutex_unlock(&gameport_mutex);
 776 }
 777 EXPORT_SYMBOL(gameport_unregister_driver);
 778
 779 static int gameport_bus_match(struct device *dev, struct device_driver *drv)
 780 {
 781         struct gameport_driver *gameport_drv = to_gameport_driver(drv);
 782
 783         return !gameport_drv->ignore;
 784 }
 785
 786 static struct bus_type gameport_bus = {
 787         .name           = "gameport",
 788         .dev_groups     = gameport_device_groups,
 789         .drv_groups     = gameport_driver_groups,
 790         .match          = gameport_bus_match,
 791         .probe          = gameport_driver_probe,
 792         .remove         = gameport_driver_remove,
 793 };
 794
 795 static void gameport_set_drv(struct gameport *gameport, struct gameport_driver *drv)
 796 {
 797         mutex_lock(&gameport->drv_mutex);
 798         gameport->drv = drv;
 799         mutex_unlock(&gameport->drv_mutex);
 800 }
 801
 802 int gameport_open(struct gameport *gameport, struct gameport_driver *drv, int mode)
 803 {
 804         if (gameport->open) {
 805                 if (gameport->open(gameport, mode)) {
 806                         return -1;
 807                 }
 808         } else {
 809                 if (mode != GAMEPORT_MODE_RAW)
 810                         return -1;
 811         }
 812
 813         gameport_set_drv(gameport, drv);
 814         return 0;
 815 }
 816 EXPORT_SYMBOL(gameport_open);
 817
 818 void gameport_close(struct gameport *gameport)
 819 {
 820         del_timer_sync(&gameport->poll_timer);
 821         gameport->poll_handler = NULL;
 822         gameport->poll_interval = 0;
 823         gameport_set_drv(gameport, NULL);
 824         if (gameport->close)
 825                 gameport->close(gameport);
 826 }
 827 EXPORT_SYMBOL(gameport_close);
 828
 829 static int __init gameport_init(void)
 830 {
 831         int error;
 832
 833         error = bus_register(&gameport_bus);
 834         if (error) {
 835                 pr_err("failed to register gameport bus, error: %d\n", error);
 836                 return error;
 837         }
 838
 839
 840         return 0;
 841 }
 842
 843 static void __exit gameport_exit(void)
 844 {
 845         bus_unregister(&gameport_bus);
 846
 847         /*
 848          * There should not be any outstanding events but work may
 849          * still be scheduled so simply cancel it.
 850          */
 851         cancel_work_sync(&gameport_event_work);
 852 }
 853
 854 subsys_initcall(gameport_init);
 855 module_exit(gameport_exit);