linux/drivers/input/gameport/gameport.c
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   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
  26MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
  27MODULE_DESCRIPTION("Generic gameport layer");
  28MODULE_LICENSE("GPL");
  29
  30static bool use_ktime = true;
  31module_param(use_ktime, bool, 0400);
  32MODULE_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 */
  38static DEFINE_MUTEX(gameport_mutex);
  39
  40static LIST_HEAD(gameport_list);
  41
  42static struct bus_type gameport_bus;
  43
  44static void gameport_add_port(struct gameport *gameport);
  45static void gameport_attach_driver(struct gameport_driver *drv);
  46static void gameport_reconnect_port(struct gameport *gameport);
  47static 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
  56static 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
  78static 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
 110static 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
 176void 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}
 188EXPORT_SYMBOL(gameport_start_polling);
 189
 190void 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}
 199EXPORT_SYMBOL(gameport_stop_polling);
 200
 201static 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
 214static 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
 238static 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
 254enum gameport_event_type {
 255        GAMEPORT_REGISTER_PORT,
 256        GAMEPORT_ATTACH_DRIVER,
 257};
 258
 259struct gameport_event {
 260        enum gameport_event_type type;
 261        void *object;
 262        struct module *owner;
 263        struct list_head node;
 264};
 265
 266static DEFINE_SPINLOCK(gameport_event_lock);    /* protects gameport_event_list */
 267static LIST_HEAD(gameport_event_list);
 268
 269static 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
 286static void gameport_free_event(struct gameport_event *event)
 287{
 288        module_put(event->owner);
 289        kfree(event);
 290}
 291
 292static 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
 318static 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
 350static DECLARE_WORK(gameport_event_work, gameport_handle_events);
 351
 352static 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
 398out:
 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 */
 407static 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 */
 432static 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
 458static 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}
 464static DEVICE_ATTR(description, S_IRUGO, gameport_description_show, NULL);
 465
 466static 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}
 494static DEVICE_ATTR_WO(drvctl);
 495
 496static struct attribute *gameport_device_attrs[] = {
 497        &dev_attr_description.attr,
 498        &dev_attr_drvctl.attr,
 499        NULL,
 500};
 501ATTRIBUTE_GROUPS(gameport_device);
 502
 503static 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
 511void 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}
 519EXPORT_SYMBOL(gameport_set_phys);
 520
 521/*
 522 * Prepare gameport port for registration.
 523 */
 524static 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 */
 548static 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 */
 579static 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 */
 606static 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 */
 623static 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 */
 654void __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}
 659EXPORT_SYMBOL(__gameport_register_port);
 660
 661/*
 662 * Synchronously unregisters gameport port.
 663 */
 664void 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}
 671EXPORT_SYMBOL(gameport_unregister_port);
 672
 673
 674/*
 675 * Gameport driver operations
 676 */
 677
 678static 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}
 683static DRIVER_ATTR_RO(description);
 684
 685static struct attribute *gameport_driver_attrs[] = {
 686        &driver_attr_description.attr,
 687        NULL
 688};
 689ATTRIBUTE_GROUPS(gameport_driver);
 690
 691static 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
 700static int 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        return 0;
 707}
 708
 709static void gameport_attach_driver(struct gameport_driver *drv)
 710{
 711        int error;
 712
 713        error = driver_attach(&drv->driver);
 714        if (error)
 715                pr_err("driver_attach() failed for %s, error: %d\n",
 716                        drv->driver.name, error);
 717}
 718
 719int __gameport_register_driver(struct gameport_driver *drv, struct module *owner,
 720                                const char *mod_name)
 721{
 722        int error;
 723
 724        drv->driver.bus = &gameport_bus;
 725        drv->driver.owner = owner;
 726        drv->driver.mod_name = mod_name;
 727
 728        /*
 729         * Temporarily disable automatic binding because probing
 730         * takes long time and we are better off doing it in kgameportd
 731         */
 732        drv->ignore = true;
 733
 734        error = driver_register(&drv->driver);
 735        if (error) {
 736                pr_err("driver_register() failed for %s, error: %d\n",
 737                        drv->driver.name, error);
 738                return error;
 739        }
 740
 741        /*
 742         * Reset ignore flag and let kgameportd bind the driver to free ports
 743         */
 744        drv->ignore = false;
 745        error = gameport_queue_event(drv, NULL, GAMEPORT_ATTACH_DRIVER);
 746        if (error) {
 747                driver_unregister(&drv->driver);
 748                return error;
 749        }
 750
 751        return 0;
 752}
 753EXPORT_SYMBOL(__gameport_register_driver);
 754
 755void gameport_unregister_driver(struct gameport_driver *drv)
 756{
 757        struct gameport *gameport;
 758
 759        mutex_lock(&gameport_mutex);
 760
 761        drv->ignore = true;     /* so gameport_find_driver ignores it */
 762        gameport_remove_pending_events(drv);
 763
 764start_over:
 765        list_for_each_entry(gameport, &gameport_list, node) {
 766                if (gameport->drv == drv) {
 767                        gameport_disconnect_port(gameport);
 768                        gameport_find_driver(gameport);
 769                        /* we could've deleted some ports, restart */
 770                        goto start_over;
 771                }
 772        }
 773
 774        driver_unregister(&drv->driver);
 775
 776        mutex_unlock(&gameport_mutex);
 777}
 778EXPORT_SYMBOL(gameport_unregister_driver);
 779
 780static int gameport_bus_match(struct device *dev, struct device_driver *drv)
 781{
 782        struct gameport_driver *gameport_drv = to_gameport_driver(drv);
 783
 784        return !gameport_drv->ignore;
 785}
 786
 787static struct bus_type gameport_bus = {
 788        .name           = "gameport",
 789        .dev_groups     = gameport_device_groups,
 790        .drv_groups     = gameport_driver_groups,
 791        .match          = gameport_bus_match,
 792        .probe          = gameport_driver_probe,
 793        .remove         = gameport_driver_remove,
 794};
 795
 796static void gameport_set_drv(struct gameport *gameport, struct gameport_driver *drv)
 797{
 798        mutex_lock(&gameport->drv_mutex);
 799        gameport->drv = drv;
 800        mutex_unlock(&gameport->drv_mutex);
 801}
 802
 803int gameport_open(struct gameport *gameport, struct gameport_driver *drv, int mode)
 804{
 805        if (gameport->open) {
 806                if (gameport->open(gameport, mode)) {
 807                        return -1;
 808                }
 809        } else {
 810                if (mode != GAMEPORT_MODE_RAW)
 811                        return -1;
 812        }
 813
 814        gameport_set_drv(gameport, drv);
 815        return 0;
 816}
 817EXPORT_SYMBOL(gameport_open);
 818
 819void gameport_close(struct gameport *gameport)
 820{
 821        del_timer_sync(&gameport->poll_timer);
 822        gameport->poll_handler = NULL;
 823        gameport->poll_interval = 0;
 824        gameport_set_drv(gameport, NULL);
 825        if (gameport->close)
 826                gameport->close(gameport);
 827}
 828EXPORT_SYMBOL(gameport_close);
 829
 830static int __init gameport_init(void)
 831{
 832        int error;
 833
 834        error = bus_register(&gameport_bus);
 835        if (error) {
 836                pr_err("failed to register gameport bus, error: %d\n", error);
 837                return error;
 838        }
 839
 840
 841        return 0;
 842}
 843
 844static void __exit gameport_exit(void)
 845{
 846        bus_unregister(&gameport_bus);
 847
 848        /*
 849         * There should not be any outstanding events but work may
 850         * still be scheduled so simply cancel it.
 851         */
 852        cancel_work_sync(&gameport_event_work);
 853}
 854
 855subsys_initcall(gameport_init);
 856module_exit(gameport_exit);
 857