drivers/input/gameport/gameport.c

   1 /*
   2  * Generic gameport layer
   3  *
   4  * Copyright (c) 1999-2002 Vojtech Pavlik
   5  * Copyright (c) 2005 Dmitry Torokhov
   6  */
   7
   8 /*
   9  * This program is free software; you can redistribute it and/or modify it
  10  * under the terms of the GNU General Public License version 2 as published by
  11  * the Free Software Foundation.
  12  */
  13
  14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  15
  16 #include <linux/stddef.h>
  17 #include <linux/module.h>
  18 #include <linux/ioport.h>
  19 #include <linux/init.h>
  20 #include <linux/gameport.h>
  21 #include <linux/slab.h>
  22 #include <linux/delay.h>
  23 #include <linux/workqueue.h>
  24 #include <linux/sched.h>        /* HZ */
  25 #include <linux/mutex.h>
  26 #include <linux/timekeeping.h>
  27
  28 /*#include <asm/io.h>*/
  29
  30 MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
  31 MODULE_DESCRIPTION("Generic gameport layer");
  32 MODULE_LICENSE("GPL");
  33
  34 static bool use_ktime = true;
  35 module_param(use_ktime, bool, 0400);
  36 MODULE_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  */
  42 static DEFINE_MUTEX(gameport_mutex);
  43
  44 static LIST_HEAD(gameport_list);
  45
  46 static struct bus_type gameport_bus;
  47
  48 static void gameport_add_port(struct gameport *gameport);
  49 static void gameport_attach_driver(struct gameport_driver *drv);
  50 static void gameport_reconnect_port(struct gameport *gameport);
  51 static 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
  60 static 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
  82 static 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
 114 static 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
 180 void 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 }
 192 EXPORT_SYMBOL(gameport_start_polling);
 193
 194 void 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 }
 203 EXPORT_SYMBOL(gameport_stop_polling);
 204
 205 static void gameport_run_poll_handler(unsigned long d)
 206 {
 207         struct gameport *gameport = (struct gameport *)d;
 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
 218 static 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
 242 static 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
 258 enum gameport_event_type {
 259         GAMEPORT_REGISTER_PORT,
 260         GAMEPORT_ATTACH_DRIVER,
 261 };
 262
 263 struct gameport_event {
 264         enum gameport_event_type type;
 265         void *object;
 266         struct module *owner;
 267         struct list_head node;
 268 };
 269
 270 static DEFINE_SPINLOCK(gameport_event_lock);    /* protects gameport_event_list */
 271 static LIST_HEAD(gameport_event_list);
 272
 273 static 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
 290 static void gameport_free_event(struct gameport_event *event)
 291 {
 292         module_put(event->owner);
 293         kfree(event);
 294 }
 295
 296 static 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
 322 static 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
 354 static DECLARE_WORK(gameport_event_work, gameport_handle_events);
 355
 356 static 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_warning("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
 402 out:
 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  */
 411 static 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  */
 436 static 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
 462 static 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 }
 468 static DEVICE_ATTR(description, S_IRUGO, gameport_description_show, NULL);
 469
 470 static 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 }
 498 static DEVICE_ATTR_WO(drvctl);
 499
 500 static struct attribute *gameport_device_attrs[] = {
 501         &dev_attr_description.attr,
 502         &dev_attr_drvctl.attr,
 503         NULL,
 504 };
 505 ATTRIBUTE_GROUPS(gameport_device);
 506
 507 static 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
 515 void 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 }
 523 EXPORT_SYMBOL(gameport_set_phys);
 524
 525 /*
 526  * Prepare gameport port for registration.
 527  */
 528 static 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         init_timer(&gameport->poll_timer);
 546         gameport->poll_timer.function = gameport_run_poll_handler;
 547         gameport->poll_timer.data = (unsigned long)gameport;
 548 }
 549
 550 /*
 551  * Complete gameport port registration.
 552  * Driver core will attempt to find appropriate driver for the port.
 553  */
 554 static void gameport_add_port(struct gameport *gameport)
 555 {
 556         int error;
 557
 558         if (gameport->parent)
 559                 gameport->parent->child = gameport;
 560
 561         gameport->speed = use_ktime ?
 562                 gameport_measure_speed(gameport) :
 563                 old_gameport_measure_speed(gameport);
 564
 565         list_add_tail(&gameport->node, &gameport_list);
 566
 567         if (gameport->io)
 568                 dev_info(&gameport->dev, "%s is %s, io %#x, speed %dkHz\n",
 569                          gameport->name, gameport->phys, gameport->io, gameport->speed);
 570         else
 571                 dev_info(&gameport->dev, "%s is %s, speed %dkHz\n",
 572                         gameport->name, gameport->phys, gameport->speed);
 573
 574         error = device_add(&gameport->dev);
 575         if (error)
 576                 dev_err(&gameport->dev,
 577                         "device_add() failed for %s (%s), error: %d\n",
 578                         gameport->phys, gameport->name, error);
 579 }
 580
 581 /*
 582  * gameport_destroy_port() completes deregistration process and removes
 583  * port from the system
 584  */
 585 static void gameport_destroy_port(struct gameport *gameport)
 586 {
 587         struct gameport *child;
 588
 589         child = gameport_get_pending_child(gameport);
 590         if (child) {
 591                 gameport_remove_pending_events(child);
 592                 put_device(&child->dev);
 593         }
 594
 595         if (gameport->parent) {
 596                 gameport->parent->child = NULL;
 597                 gameport->parent = NULL;
 598         }
 599
 600         if (device_is_registered(&gameport->dev))
 601                 device_del(&gameport->dev);
 602
 603         list_del_init(&gameport->node);
 604
 605         gameport_remove_pending_events(gameport);
 606         put_device(&gameport->dev);
 607 }
 608
 609 /*
 610  * Reconnect gameport port and all its children (re-initialize attached devices)
 611  */
 612 static void gameport_reconnect_port(struct gameport *gameport)
 613 {
 614         do {
 615                 if (!gameport->drv || !gameport->drv->reconnect || gameport->drv->reconnect(gameport)) {
 616                         gameport_disconnect_port(gameport);
 617                         gameport_find_driver(gameport);
 618                         /* Ok, old children are now gone, we are done */
 619                         break;
 620                 }
 621                 gameport = gameport->child;
 622         } while (gameport);
 623 }
 624
 625 /*
 626  * gameport_disconnect_port() unbinds a port from its driver. As a side effect
 627  * all child ports are unbound and destroyed.
 628  */
 629 static void gameport_disconnect_port(struct gameport *gameport)
 630 {
 631         struct gameport *s, *parent;
 632
 633         if (gameport->child) {
 634                 /*
 635                  * Children ports should be disconnected and destroyed
 636                  * first, staring with the leaf one, since we don't want
 637                  * to do recursion
 638                  */
 639                 for (s = gameport; s->child; s = s->child)
 640                         /* empty */;
 641
 642                 do {
 643                         parent = s->parent;
 644
 645                         device_release_driver(&s->dev);
 646                         gameport_destroy_port(s);
 647                 } while ((s = parent) != gameport);
 648         }
 649
 650         /*
 651          * Ok, no children left, now disconnect this port
 652          */
 653         device_release_driver(&gameport->dev);
 654 }
 655
 656 /*
 657  * Submits register request to kgameportd for subsequent execution.
 658  * Note that port registration is always asynchronous.
 659  */
 660 void __gameport_register_port(struct gameport *gameport, struct module *owner)
 661 {
 662         gameport_init_port(gameport);
 663         gameport_queue_event(gameport, owner, GAMEPORT_REGISTER_PORT);
 664 }
 665 EXPORT_SYMBOL(__gameport_register_port);
 666
 667 /*
 668  * Synchronously unregisters gameport port.
 669  */
 670 void gameport_unregister_port(struct gameport *gameport)
 671 {
 672         mutex_lock(&gameport_mutex);
 673         gameport_disconnect_port(gameport);
 674         gameport_destroy_port(gameport);
 675         mutex_unlock(&gameport_mutex);
 676 }
 677 EXPORT_SYMBOL(gameport_unregister_port);
 678
 679
 680 /*
 681  * Gameport driver operations
 682  */
 683
 684 static ssize_t description_show(struct device_driver *drv, char *buf)
 685 {
 686         struct gameport_driver *driver = to_gameport_driver(drv);
 687         return sprintf(buf, "%s\n", driver->description ? driver->description : "(none)");
 688 }
 689 static DRIVER_ATTR_RO(description);
 690
 691 static struct attribute *gameport_driver_attrs[] = {
 692         &driver_attr_description.attr,
 693         NULL
 694 };
 695 ATTRIBUTE_GROUPS(gameport_driver);
 696
 697 static int gameport_driver_probe(struct device *dev)
 698 {
 699         struct gameport *gameport = to_gameport_port(dev);
 700         struct gameport_driver *drv = to_gameport_driver(dev->driver);
 701
 702         drv->connect(gameport, drv);
 703         return gameport->drv ? 0 : -ENODEV;
 704 }
 705
 706 static int gameport_driver_remove(struct device *dev)
 707 {
 708         struct gameport *gameport = to_gameport_port(dev);
 709         struct gameport_driver *drv = to_gameport_driver(dev->driver);
 710
 711         drv->disconnect(gameport);
 712         return 0;
 713 }
 714
 715 static void gameport_attach_driver(struct gameport_driver *drv)
 716 {
 717         int error;
 718
 719         error = driver_attach(&drv->driver);
 720         if (error)
 721                 pr_err("driver_attach() failed for %s, error: %d\n",
 722                         drv->driver.name, error);
 723 }
 724
 725 int __gameport_register_driver(struct gameport_driver *drv, struct module *owner,
 726                                 const char *mod_name)
 727 {
 728         int error;
 729
 730         drv->driver.bus = &gameport_bus;
 731         drv->driver.owner = owner;
 732         drv->driver.mod_name = mod_name;
 733
 734         /*
 735          * Temporarily disable automatic binding because probing
 736          * takes long time and we are better off doing it in kgameportd
 737          */
 738         drv->ignore = true;
 739
 740         error = driver_register(&drv->driver);
 741         if (error) {
 742                 pr_err("driver_register() failed for %s, error: %d\n",
 743                         drv->driver.name, error);
 744                 return error;
 745         }
 746
 747         /*
 748          * Reset ignore flag and let kgameportd bind the driver to free ports
 749          */
 750         drv->ignore = false;
 751         error = gameport_queue_event(drv, NULL, GAMEPORT_ATTACH_DRIVER);
 752         if (error) {
 753                 driver_unregister(&drv->driver);
 754                 return error;
 755         }
 756
 757         return 0;
 758 }
 759 EXPORT_SYMBOL(__gameport_register_driver);
 760
 761 void gameport_unregister_driver(struct gameport_driver *drv)
 762 {
 763         struct gameport *gameport;
 764
 765         mutex_lock(&gameport_mutex);
 766
 767         drv->ignore = true;     /* so gameport_find_driver ignores it */
 768         gameport_remove_pending_events(drv);
 769
 770 start_over:
 771         list_for_each_entry(gameport, &gameport_list, node) {
 772                 if (gameport->drv == drv) {
 773                         gameport_disconnect_port(gameport);
 774                         gameport_find_driver(gameport);
 775                         /* we could've deleted some ports, restart */
 776                         goto start_over;
 777                 }
 778         }
 779
 780         driver_unregister(&drv->driver);
 781
 782         mutex_unlock(&gameport_mutex);
 783 }
 784 EXPORT_SYMBOL(gameport_unregister_driver);
 785
 786 static int gameport_bus_match(struct device *dev, struct device_driver *drv)
 787 {
 788         struct gameport_driver *gameport_drv = to_gameport_driver(drv);
 789
 790         return !gameport_drv->ignore;
 791 }
 792
 793 static struct bus_type gameport_bus = {
 794         .name           = "gameport",
 795         .dev_groups     = gameport_device_groups,
 796         .drv_groups     = gameport_driver_groups,
 797         .match          = gameport_bus_match,
 798         .probe          = gameport_driver_probe,
 799         .remove         = gameport_driver_remove,
 800 };
 801
 802 static void gameport_set_drv(struct gameport *gameport, struct gameport_driver *drv)
 803 {
 804         mutex_lock(&gameport->drv_mutex);
 805         gameport->drv = drv;
 806         mutex_unlock(&gameport->drv_mutex);
 807 }
 808
 809 int gameport_open(struct gameport *gameport, struct gameport_driver *drv, int mode)
 810 {
 811         if (gameport->open) {
 812                 if (gameport->open(gameport, mode)) {
 813                         return -1;
 814                 }
 815         } else {
 816                 if (mode != GAMEPORT_MODE_RAW)
 817                         return -1;
 818         }
 819
 820         gameport_set_drv(gameport, drv);
 821         return 0;
 822 }
 823 EXPORT_SYMBOL(gameport_open);
 824
 825 void gameport_close(struct gameport *gameport)
 826 {
 827         del_timer_sync(&gameport->poll_timer);
 828         gameport->poll_handler = NULL;
 829         gameport->poll_interval = 0;
 830         gameport_set_drv(gameport, NULL);
 831         if (gameport->close)
 832                 gameport->close(gameport);
 833 }
 834 EXPORT_SYMBOL(gameport_close);
 835
 836 static int __init gameport_init(void)
 837 {
 838         int error;
 839
 840         error = bus_register(&gameport_bus);
 841         if (error) {
 842                 pr_err("failed to register gameport bus, error: %d\n", error);
 843                 return error;
 844         }
 845
 846
 847         return 0;
 848 }
 849
 850 static void __exit gameport_exit(void)
 851 {
 852         bus_unregister(&gameport_bus);
 853
 854         /*
 855          * There should not be any outstanding events but work may
 856          * still be scheduled so simply cancel it.
 857          */
 858         cancel_work_sync(&gameport_event_work);
 859 }
 860
 861 subsys_initcall(gameport_init);
 862 module_exit(gameport_exit);