text: /*
   * 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 <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_cooked_read);
  EXPORT_SYMBOL(gameport_set_name);
  EXPORT_SYMBOL(gameport_set_phys);
  EXPORT_SYMBOL(gameport_start_polling);
  EXPORT_SYMBOL(gameport_stop_polling);
  
  /*
   * gameport_sem protects entire gameport subsystem and is taken
   * every time gameport port or driver registrered or unregistered.
   */
  static DECLARE_MUTEX(gameport_sem);
  
  static LIST_HEAD(gameport_list);
  
  static struct bus_type gameport_bus;
  
  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 void gameport_bind_driver(struct gameport *gameport, struct gameport_driver *drv)
  {
  	down_write(&gameport_bus.subsys.rwsem);
  
  	gameport->dev.driver = &drv->driver;
  	if (drv->connect(gameport, drv)) {
  		gameport->dev.driver = NULL;
  		goto out;
  	}
  	device_bind_driver(&gameport->dev);
  out:
  	up_write(&gameport_bus.subsys.rwsem);
  }
  
  static void gameport_release_driver(struct gameport *gameport)
  {
  	down_write(&gameport_bus.subsys.rwsem);
  	device_release_driver(&gameport->dev);
  	up_write(&gameport_bus.subsys.rwsem);
  }
  
  static void gameport_find_driver(struct gameport *gameport)
  {
  	down_write(&gameport_bus.subsys.rwsem);
  	device_attach(&gameport->dev);
  	up_write(&gameport_bus.subsys.rwsem);
  }
  
  
  /*
   * 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);
  			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;
  	struct gameport_driver *gameport_drv;
  
  	down(&gameport_sem);
  
  	/*
  	 * 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_drv = event->object;
  				driver_register(&gameport_drv->driver);
  				break;
  
  			default:
  				break;
  		}
  
  		gameport_remove_duplicate_events(event);
  		gameport_free_event(event);
  	}
  
  	up(&gameport_sem);
  }
  
  /*
   * 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)
  {
  	do {
  		gameport_handle_event();
  		wait_event_interruptible(gameport_wait,
  			kthread_should_stop() || !list_empty(&gameport_event_list));
  		try_to_freeze();
  	} 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 retval;
  
  	retval = down_interruptible(&gameport_sem);
  	if (retval)
  		return retval;
  
  	retval = count;
  	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);
  		gameport_bind_driver(gameport, to_gameport_driver(drv));
  		put_driver(drv);
  	} else {
  		retval = -EINVAL;
  	}
  
  	up(&gameport_sem);
  
  	return retval;
  }
  
  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);
  
  	init_MUTEX(&gameport->drv_sem);
  	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;
  
  	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)
  {
  	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);
  
  	device_add(&gameport->dev);
  	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);
  		list_del_init(&gameport->node);
  		gameport->registered = 0;
  	}
  
  	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;
  
  			gameport_release_driver(s);
  			gameport_destroy_port(s);
  		} while ((s = parent) != gameport);
  	}
  
  	/*
  	 * Ok, no children left, now disconnect this port
  	 */
  	gameport_release_driver(gameport);
  }
  
  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)
  {
  	down(&gameport_sem);
  	gameport_disconnect_port(gameport);
  	gameport_destroy_port(gameport);
  	up(&gameport_sem);
  }
  
  
  /*
   * 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 struct bus_type gameport_bus = {
  	.name =	"gameport",
  	.probe = gameport_driver_probe,
  	.remove = gameport_driver_remove,
  };
  
  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;
  
  	down(&gameport_sem);
  	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);
  	up(&gameport_sem);
  }
  
  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 void gameport_set_drv(struct gameport *gameport, struct gameport_driver *drv)
  {
  	down(&gameport->drv_sem);
  	gameport->drv = drv;
  	up(&gameport->drv_sem);
  }
  
  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)
  {
  	gameport_task = kthread_run(gameport_thread, NULL, "kgameportd");
  	if (IS_ERR(gameport_task)) {
  		printk(KERN_ERR "gameport: Failed to start kgameportd\n");
  		return PTR_ERR(gameport_task);
  	}
  
  	gameport_bus.dev_attrs = gameport_device_attrs;
  	gameport_bus.drv_attrs = gameport_driver_attrs;
  	gameport_bus.match = gameport_bus_match;
  	bus_register(&gameport_bus);
  
  	return 0;
  }
  
  static void __exit gameport_exit(void)
  {
  	bus_unregister(&gameport_bus);
  	kthread_stop(gameport_task);
  }
  
  module_init(gameport_init);
  module_exit(gameport_exit);
  