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