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gameport.c

/*
 * Generic gameport layer
 *
 * Copyright (c) 1999-2002 Vojtech Pavlik
 * Copyright (c) 2005 Dmitry Torokhov
 */

/*
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 */

#include <linux/stddef.h>
#include <linux/module.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/gameport.h>
#include <linux/wait.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/kthread.h>
#include <linux/sched.h>      /* HZ */
#include <linux/mutex.h>
#include <linux/freezer.h>

/*#include <asm/io.h>*/

MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
MODULE_DESCRIPTION("Generic gameport layer");
MODULE_LICENSE("GPL");

EXPORT_SYMBOL(__gameport_register_port);
EXPORT_SYMBOL(gameport_unregister_port);
EXPORT_SYMBOL(__gameport_register_driver);
EXPORT_SYMBOL(gameport_unregister_driver);
EXPORT_SYMBOL(gameport_open);
EXPORT_SYMBOL(gameport_close);
EXPORT_SYMBOL(gameport_rescan);
EXPORT_SYMBOL(gameport_set_phys);
EXPORT_SYMBOL(gameport_start_polling);
EXPORT_SYMBOL(gameport_stop_polling);

/*
 * gameport_mutex protects entire gameport subsystem and is taken
 * every time gameport port or driver registrered or unregistered.
 */
static DEFINE_MUTEX(gameport_mutex);

static LIST_HEAD(gameport_list);

static struct bus_type gameport_bus;

static void gameport_add_driver(struct gameport_driver *drv);
static void gameport_add_port(struct gameport *gameport);
static void gameport_destroy_port(struct gameport *gameport);
static void gameport_reconnect_port(struct gameport *gameport);
static void gameport_disconnect_port(struct gameport *gameport);

#if defined(__i386__)

#include <asm/i8253.h>

#define DELTA(x,y)      ((y)-(x)+((y)<(x)?1193182/HZ:0))
#define GET_TIME(x)     do { x = get_time_pit(); } while (0)

static unsigned int get_time_pit(void)
{
      unsigned long flags;
      unsigned int count;

      spin_lock_irqsave(&i8253_lock, flags);
      outb_p(0x00, 0x43);
      count = inb_p(0x40);
      count |= inb_p(0x40) << 8;
      spin_unlock_irqrestore(&i8253_lock, flags);

      return count;
}

#endif



/*
 * gameport_measure_speed() measures the gameport i/o speed.
 */

static int gameport_measure_speed(struct gameport *gameport)
{
#if defined(__i386__)

      unsigned int i, t, t1, t2, t3, tx;
      unsigned long flags;

      if (gameport_open(gameport, NULL, GAMEPORT_MODE_RAW))
            return 0;

      tx = 1 << 30;

      for(i = 0; i < 50; i++) {
            local_irq_save(flags);
            GET_TIME(t1);
            for (t = 0; t < 50; t++) gameport_read(gameport);
            GET_TIME(t2);
            GET_TIME(t3);
            local_irq_restore(flags);
            udelay(i * 10);
            if ((t = DELTA(t2,t1) - DELTA(t3,t2)) < tx) tx = t;
      }

      gameport_close(gameport);
      return 59659 / (tx < 1 ? 1 : tx);

#elif defined (__x86_64__)

      unsigned int i, t;
      unsigned long tx, t1, t2, flags;

      if (gameport_open(gameport, NULL, GAMEPORT_MODE_RAW))
            return 0;

      tx = 1 << 30;

      for(i = 0; i < 50; i++) {
            local_irq_save(flags);
            rdtscl(t1);
            for (t = 0; t < 50; t++) gameport_read(gameport);
            rdtscl(t2);
            local_irq_restore(flags);
            udelay(i * 10);
            if (t2 - t1 < tx) tx = t2 - t1;
      }

      gameport_close(gameport);
      return (cpu_data(raw_smp_processor_id()).loops_per_jiffy *
            (unsigned long)HZ / (1000 / 50)) / (tx < 1 ? 1 : tx);

#else

      unsigned int j, t = 0;

      if (gameport_open(gameport, NULL, GAMEPORT_MODE_RAW))
            return 0;

      j = jiffies; while (j == jiffies);
      j = jiffies; while (j == jiffies) { t++; gameport_read(gameport); }

      gameport_close(gameport);
      return t * HZ / 1000;

#endif
}

void gameport_start_polling(struct gameport *gameport)
{
      spin_lock(&gameport->timer_lock);

      if (!gameport->poll_cnt++) {
            BUG_ON(!gameport->poll_handler);
            BUG_ON(!gameport->poll_interval);
            mod_timer(&gameport->poll_timer, jiffies + msecs_to_jiffies(gameport->poll_interval));
      }

      spin_unlock(&gameport->timer_lock);
}

void gameport_stop_polling(struct gameport *gameport)
{
      spin_lock(&gameport->timer_lock);

      if (!--gameport->poll_cnt)
            del_timer(&gameport->poll_timer);

      spin_unlock(&gameport->timer_lock);
}

static void gameport_run_poll_handler(unsigned long d)
{
      struct gameport *gameport = (struct gameport *)d;

      gameport->poll_handler(gameport);
      if (gameport->poll_cnt)
            mod_timer(&gameport->poll_timer, jiffies + msecs_to_jiffies(gameport->poll_interval));
}

/*
 * Basic gameport -> driver core mappings
 */

static int gameport_bind_driver(struct gameport *gameport, struct gameport_driver *drv)
{
      int error;

      gameport->dev.driver = &drv->driver;
      if (drv->connect(gameport, drv)) {
            gameport->dev.driver = NULL;
            return -ENODEV;
      }

      error = device_bind_driver(&gameport->dev);
      if (error) {
            printk(KERN_WARNING
                  "gameport: device_bind_driver() failed "
                  "for %s (%s) and %s, error: %d\n",
                  gameport->phys, gameport->name,
                  drv->description, error);
            drv->disconnect(gameport);
            gameport->dev.driver = NULL;
            return error;
      }

      return 0;
}

static void gameport_find_driver(struct gameport *gameport)
{
      int error;

      error = device_attach(&gameport->dev);
      if (error < 0)
            printk(KERN_WARNING
                  "gameport: device_attach() failed for %s (%s), error: %d\n",
                  gameport->phys, gameport->name, error);
}


/*
 * Gameport event processing.
 */

enum gameport_event_type {
      GAMEPORT_RESCAN,
      GAMEPORT_RECONNECT,
      GAMEPORT_REGISTER_PORT,
      GAMEPORT_REGISTER_DRIVER,
};

struct gameport_event {
      enum gameport_event_type type;
      void *object;
      struct module *owner;
      struct list_head node;
};

static DEFINE_SPINLOCK(gameport_event_lock);    /* protects gameport_event_list */
static LIST_HEAD(gameport_event_list);
static DECLARE_WAIT_QUEUE_HEAD(gameport_wait);
static struct task_struct *gameport_task;

static void gameport_queue_event(void *object, struct module *owner,
                        enum gameport_event_type event_type)
{
      unsigned long flags;
      struct gameport_event *event;

      spin_lock_irqsave(&gameport_event_lock, flags);

      /*
       * Scan event list for the other events for the same gameport port,
       * starting with the most recent one. If event is the same we
       * do not need add new one. If event is of different type we
       * need to add this event and should not look further because
       * we need to preseve sequence of distinct events.
       */
      list_for_each_entry_reverse(event, &gameport_event_list, node) {
            if (event->object == object) {
                  if (event->type == event_type)
                        goto out;
                  break;
            }
      }

      if ((event = kmalloc(sizeof(struct gameport_event), GFP_ATOMIC))) {
            if (!try_module_get(owner)) {
                  printk(KERN_WARNING "gameport: Can't get module reference, dropping event %d\n", event_type);
                  kfree(event);
                  goto out;
            }

            event->type = event_type;
            event->object = object;
            event->owner = owner;

            list_add_tail(&event->node, &gameport_event_list);
            wake_up(&gameport_wait);
      } else {
            printk(KERN_ERR "gameport: Not enough memory to queue event %d\n", event_type);
      }
out:
      spin_unlock_irqrestore(&gameport_event_lock, flags);
}

static void gameport_free_event(struct gameport_event *event)
{
      module_put(event->owner);
      kfree(event);
}

static void gameport_remove_duplicate_events(struct gameport_event *event)
{
      struct list_head *node, *next;
      struct gameport_event *e;
      unsigned long flags;

      spin_lock_irqsave(&gameport_event_lock, flags);

      list_for_each_safe(node, next, &gameport_event_list) {
            e = list_entry(node, struct gameport_event, node);
            if (event->object == e->object) {
                  /*
                   * If this event is of different type we should not
                   * look further - we only suppress duplicate events
                   * that were sent back-to-back.
                   */
                  if (event->type != e->type)
                        break;

                  list_del_init(node);
                  gameport_free_event(e);
            }
      }

      spin_unlock_irqrestore(&gameport_event_lock, flags);
}

static struct gameport_event *gameport_get_event(void)
{
      struct gameport_event *event;
      struct list_head *node;
      unsigned long flags;

      spin_lock_irqsave(&gameport_event_lock, flags);

      if (list_empty(&gameport_event_list)) {
            spin_unlock_irqrestore(&gameport_event_lock, flags);
            return NULL;
      }

      node = gameport_event_list.next;
      event = list_entry(node, struct gameport_event, node);
      list_del_init(node);

      spin_unlock_irqrestore(&gameport_event_lock, flags);

      return event;
}

static void gameport_handle_event(void)
{
      struct gameport_event *event;

      mutex_lock(&gameport_mutex);

      /*
       * Note that we handle only one event here to give swsusp
       * a chance to freeze kgameportd thread. Gameport events
       * should be pretty rare so we are not concerned about
       * taking performance hit.
       */
      if ((event = gameport_get_event())) {

            switch (event->type) {
                  case GAMEPORT_REGISTER_PORT:
                        gameport_add_port(event->object);
                        break;

                  case GAMEPORT_RECONNECT:
                        gameport_reconnect_port(event->object);
                        break;

                  case GAMEPORT_RESCAN:
                        gameport_disconnect_port(event->object);
                        gameport_find_driver(event->object);
                        break;

                  case GAMEPORT_REGISTER_DRIVER:
                        gameport_add_driver(event->object);
                        break;

                  default:
                        break;
            }

            gameport_remove_duplicate_events(event);
            gameport_free_event(event);
      }

      mutex_unlock(&gameport_mutex);
}

/*
 * Remove all events that have been submitted for a given gameport port.
 */
static void gameport_remove_pending_events(struct gameport *gameport)
{
      struct list_head *node, *next;
      struct gameport_event *event;
      unsigned long flags;

      spin_lock_irqsave(&gameport_event_lock, flags);

      list_for_each_safe(node, next, &gameport_event_list) {
            event = list_entry(node, struct gameport_event, node);
            if (event->object == gameport) {
                  list_del_init(node);
                  gameport_free_event(event);
            }
      }

      spin_unlock_irqrestore(&gameport_event_lock, flags);
}

/*
 * Destroy child gameport port (if any) that has not been fully registered yet.
 *
 * Note that we rely on the fact that port can have only one child and therefore
 * only one child registration request can be pending. Additionally, children
 * are registered by driver's connect() handler so there can't be a grandchild
 * pending registration together with a child.
 */
static struct gameport *gameport_get_pending_child(struct gameport *parent)
{
      struct gameport_event *event;
      struct gameport *gameport, *child = NULL;
      unsigned long flags;

      spin_lock_irqsave(&gameport_event_lock, flags);

      list_for_each_entry(event, &gameport_event_list, node) {
            if (event->type == GAMEPORT_REGISTER_PORT) {
                  gameport = event->object;
                  if (gameport->parent == parent) {
                        child = gameport;
                        break;
                  }
            }
      }

      spin_unlock_irqrestore(&gameport_event_lock, flags);
      return child;
}

static int gameport_thread(void *nothing)
{
      set_freezable();
      do {
            gameport_handle_event();
            wait_event_freezable(gameport_wait,
                  kthread_should_stop() || !list_empty(&gameport_event_list));
      } while (!kthread_should_stop());

      printk(KERN_DEBUG "gameport: kgameportd exiting\n");
      return 0;
}


/*
 * Gameport port operations
 */

static ssize_t gameport_show_description(struct device *dev, struct device_attribute *attr, char *buf)
{
      struct gameport *gameport = to_gameport_port(dev);
      return sprintf(buf, "%s\n", gameport->name);
}

static ssize_t gameport_rebind_driver(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
{
      struct gameport *gameport = to_gameport_port(dev);
      struct device_driver *drv;
      int error;

      error = mutex_lock_interruptible(&gameport_mutex);
      if (error)
            return error;

      if (!strncmp(buf, "none", count)) {
            gameport_disconnect_port(gameport);
      } else if (!strncmp(buf, "reconnect", count)) {
            gameport_reconnect_port(gameport);
      } else if (!strncmp(buf, "rescan", count)) {
            gameport_disconnect_port(gameport);
            gameport_find_driver(gameport);
      } else if ((drv = driver_find(buf, &gameport_bus)) != NULL) {
            gameport_disconnect_port(gameport);
            error = gameport_bind_driver(gameport, to_gameport_driver(drv));
            put_driver(drv);
      } else {
            error = -EINVAL;
      }

      mutex_unlock(&gameport_mutex);

      return error ? error : count;
}

static struct device_attribute gameport_device_attrs[] = {
      __ATTR(description, S_IRUGO, gameport_show_description, NULL),
      __ATTR(drvctl, S_IWUSR, NULL, gameport_rebind_driver),
      __ATTR_NULL
};

static void gameport_release_port(struct device *dev)
{
      struct gameport *gameport = to_gameport_port(dev);

      kfree(gameport);
      module_put(THIS_MODULE);
}

void gameport_set_phys(struct gameport *gameport, const char *fmt, ...)
{
      va_list args;

      va_start(args, fmt);
      vsnprintf(gameport->phys, sizeof(gameport->phys), fmt, args);
      va_end(args);
}

/*
 * Prepare gameport port for registration.
 */
static void gameport_init_port(struct gameport *gameport)
{
      static atomic_t gameport_no = ATOMIC_INIT(0);

      __module_get(THIS_MODULE);

      mutex_init(&gameport->drv_mutex);
      device_initialize(&gameport->dev);
      snprintf(gameport->dev.bus_id, sizeof(gameport->dev.bus_id),
             "gameport%lu", (unsigned long)atomic_inc_return(&gameport_no) - 1);
      gameport->dev.bus = &gameport_bus;
      gameport->dev.release = gameport_release_port;
      if (gameport->parent)
            gameport->dev.parent = &gameport->parent->dev;

      INIT_LIST_HEAD(&gameport->node);
      spin_lock_init(&gameport->timer_lock);
      init_timer(&gameport->poll_timer);
      gameport->poll_timer.function = gameport_run_poll_handler;
      gameport->poll_timer.data = (unsigned long)gameport;
}

/*
 * Complete gameport port registration.
 * Driver core will attempt to find appropriate driver for the port.
 */
static void gameport_add_port(struct gameport *gameport)
{
      int error;

      if (gameport->parent)
            gameport->parent->child = gameport;

      gameport->speed = gameport_measure_speed(gameport);

      list_add_tail(&gameport->node, &gameport_list);

      if (gameport->io)
            printk(KERN_INFO "gameport: %s is %s, io %#x, speed %dkHz\n",
                  gameport->name, gameport->phys, gameport->io, gameport->speed);
      else
            printk(KERN_INFO "gameport: %s is %s, speed %dkHz\n",
                  gameport->name, gameport->phys, gameport->speed);

      error = device_add(&gameport->dev);
      if (error)
            printk(KERN_ERR
                  "gameport: device_add() failed for %s (%s), error: %d\n",
                  gameport->phys, gameport->name, error);
      else
            gameport->registered = 1;
}

/*
 * gameport_destroy_port() completes deregistration process and removes
 * port from the system
 */
static void gameport_destroy_port(struct gameport *gameport)
{
      struct gameport *child;

      child = gameport_get_pending_child(gameport);
      if (child) {
            gameport_remove_pending_events(child);
            put_device(&child->dev);
      }

      if (gameport->parent) {
            gameport->parent->child = NULL;
            gameport->parent = NULL;
      }

      if (gameport->registered) {
            device_del(&gameport->dev);
            gameport->registered = 0;
      }

      list_del_init(&gameport->node);

      gameport_remove_pending_events(gameport);
      put_device(&gameport->dev);
}

/*
 * Reconnect gameport port and all its children (re-initialize attached devices)
 */
static void gameport_reconnect_port(struct gameport *gameport)
{
      do {
            if (!gameport->drv || !gameport->drv->reconnect || gameport->drv->reconnect(gameport)) {
                  gameport_disconnect_port(gameport);
                  gameport_find_driver(gameport);
                  /* Ok, old children are now gone, we are done */
                  break;
            }
            gameport = gameport->child;
      } while (gameport);
}

/*
 * gameport_disconnect_port() unbinds a port from its driver. As a side effect
 * all child ports are unbound and destroyed.
 */
static void gameport_disconnect_port(struct gameport *gameport)
{
      struct gameport *s, *parent;

      if (gameport->child) {
            /*
             * Children ports should be disconnected and destroyed
             * first, staring with the leaf one, since we don't want
             * to do recursion
             */
            for (s = gameport; s->child; s = s->child)
                  /* empty */;

            do {
                  parent = s->parent;

                  device_release_driver(&s->dev);
                  gameport_destroy_port(s);
            } while ((s = parent) != gameport);
      }

      /*
       * Ok, no children left, now disconnect this port
       */
      device_release_driver(&gameport->dev);
}

void gameport_rescan(struct gameport *gameport)
{
      gameport_queue_event(gameport, NULL, GAMEPORT_RESCAN);
}

void gameport_reconnect(struct gameport *gameport)
{
      gameport_queue_event(gameport, NULL, GAMEPORT_RECONNECT);
}

/*
 * Submits register request to kgameportd for subsequent execution.
 * Note that port registration is always asynchronous.
 */
void __gameport_register_port(struct gameport *gameport, struct module *owner)
{
      gameport_init_port(gameport);
      gameport_queue_event(gameport, owner, GAMEPORT_REGISTER_PORT);
}

/*
 * Synchronously unregisters gameport port.
 */
void gameport_unregister_port(struct gameport *gameport)
{
      mutex_lock(&gameport_mutex);
      gameport_disconnect_port(gameport);
      gameport_destroy_port(gameport);
      mutex_unlock(&gameport_mutex);
}


/*
 * Gameport driver operations
 */

static ssize_t gameport_driver_show_description(struct device_driver *drv, char *buf)
{
      struct gameport_driver *driver = to_gameport_driver(drv);
      return sprintf(buf, "%s\n", driver->description ? driver->description : "(none)");
}

static struct driver_attribute gameport_driver_attrs[] = {
      __ATTR(description, S_IRUGO, gameport_driver_show_description, NULL),
      __ATTR_NULL
};

static int gameport_driver_probe(struct device *dev)
{
      struct gameport *gameport = to_gameport_port(dev);
      struct gameport_driver *drv = to_gameport_driver(dev->driver);

      drv->connect(gameport, drv);
      return gameport->drv ? 0 : -ENODEV;
}

static int gameport_driver_remove(struct device *dev)
{
      struct gameport *gameport = to_gameport_port(dev);
      struct gameport_driver *drv = to_gameport_driver(dev->driver);

      drv->disconnect(gameport);
      return 0;
}

static void gameport_add_driver(struct gameport_driver *drv)
{
      int error;

      error = driver_register(&drv->driver);
      if (error)
            printk(KERN_ERR
                  "gameport: driver_register() failed for %s, error: %d\n",
                  drv->driver.name, error);
}

void __gameport_register_driver(struct gameport_driver *drv, struct module *owner)
{
      drv->driver.bus = &gameport_bus;
      gameport_queue_event(drv, owner, GAMEPORT_REGISTER_DRIVER);
}

void gameport_unregister_driver(struct gameport_driver *drv)
{
      struct gameport *gameport;

      mutex_lock(&gameport_mutex);
      drv->ignore = 1;  /* so gameport_find_driver ignores it */

start_over:
      list_for_each_entry(gameport, &gameport_list, node) {
            if (gameport->drv == drv) {
                  gameport_disconnect_port(gameport);
                  gameport_find_driver(gameport);
                  /* we could've deleted some ports, restart */
                  goto start_over;
            }
      }

      driver_unregister(&drv->driver);
      mutex_unlock(&gameport_mutex);
}

static int gameport_bus_match(struct device *dev, struct device_driver *drv)
{
      struct gameport_driver *gameport_drv = to_gameport_driver(drv);

      return !gameport_drv->ignore;
}

static struct bus_type gameport_bus = {
      .name       = "gameport",
      .dev_attrs  = gameport_device_attrs,
      .drv_attrs  = gameport_driver_attrs,
      .match            = gameport_bus_match,
      .probe            = gameport_driver_probe,
      .remove           = gameport_driver_remove,
};

static void gameport_set_drv(struct gameport *gameport, struct gameport_driver *drv)
{
      mutex_lock(&gameport->drv_mutex);
      gameport->drv = drv;
      mutex_unlock(&gameport->drv_mutex);
}

int gameport_open(struct gameport *gameport, struct gameport_driver *drv, int mode)
{
      if (gameport->open) {
            if (gameport->open(gameport, mode)) {
                  return -1;
            }
      } else {
            if (mode != GAMEPORT_MODE_RAW)
                  return -1;
      }

      gameport_set_drv(gameport, drv);
      return 0;
}

void gameport_close(struct gameport *gameport)
{
      del_timer_sync(&gameport->poll_timer);
      gameport->poll_handler = NULL;
      gameport->poll_interval = 0;
      gameport_set_drv(gameport, NULL);
      if (gameport->close)
            gameport->close(gameport);
}

static int __init gameport_init(void)
{
      int error;

      error = bus_register(&gameport_bus);
      if (error) {
            printk(KERN_ERR "gameport: failed to register gameport bus, error: %d\n", error);
            return error;
      }

      gameport_task = kthread_run(gameport_thread, NULL, "kgameportd");
      if (IS_ERR(gameport_task)) {
            bus_unregister(&gameport_bus);
            error = PTR_ERR(gameport_task);
            printk(KERN_ERR "gameport: Failed to start kgameportd, error: %d\n", error);
            return error;
      }

      return 0;
}

static void __exit gameport_exit(void)
{
      bus_unregister(&gameport_bus);
      kthread_stop(gameport_task);
}

subsys_initcall(gameport_init);
module_exit(gameport_exit);

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