/*
 * Copyright (c) 2001-2004 Jakub Jermar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup time
 * @{
 */

/**
 * @file
 * @brief Timeout management functions.
 */

#include <time/timeout.h>
#include <typedefs.h>
#include <config.h>
#include <panic.h>
#include <synch/spinlock.h>
#include <func.h>
#include <cpu.h>
#include <arch/asm.h>
#include <arch.h>

/** Initialize timeouts
 *
 * Initialize kernel timeouts.
 *
 */
void timeout_init(void)
{
	irq_spinlock_initialize(&CPU->timeoutlock, "cpu.timeoutlock");
	list_initialize(&CPU->timeout_active_head);
}

/** Reinitialize timeout
 *
 * Initialize all members except the lock.
 *
 * @param timeout Timeout to be initialized.
 *
 */
void timeout_reinitialize(timeout_t *timeout)
{
	timeout->cpu = NULL;
	timeout->ticks = 0;
	timeout->handler = NULL;
	timeout->arg = NULL;
	link_initialize(&timeout->link);
}

/** Initialize timeout
 *
 * Initialize all members including the lock.
 *
 * @param timeout Timeout to be initialized.
 *
 */
void timeout_initialize(timeout_t *timeout)
{
	irq_spinlock_initialize(&timeout->lock, "timeout_t_lock");
	timeout_reinitialize(timeout);
}

/** Register timeout
 *
 * Insert timeout handler f (with argument arg)
 * to timeout list and make it execute in
 * time microseconds (or slightly more).
 *
 * @param timeout Timeout structure.
 * @param time    Number of usec in the future to execute the handler.
 * @param handler Timeout handler function.
 * @param arg     Timeout handler argument.
 *
 */
void timeout_register(timeout_t *timeout, uint64_t time,
    timeout_handler_t handler, void *arg)
{
	irq_spinlock_lock(&CPU->timeoutlock, true);
	irq_spinlock_lock(&timeout->lock, false);
	
	if (timeout->cpu)
		panic("Unexpected: timeout->cpu != 0.");
	
	timeout->cpu = CPU;
	timeout->ticks = us2ticks(time);
	
	timeout->handler = handler;
	timeout->arg = arg;
	
	/*
	 * Insert timeout into the active timeouts list according to timeout->ticks.
	 */
	uint64_t sum = 0;
	timeout_t *target = NULL;
	link_t *cur;
	for (cur = CPU->timeout_active_head.next;
	    cur != &CPU->timeout_active_head; cur = cur->next) {
		target = list_get_instance(cur, timeout_t, link);
		irq_spinlock_lock(&target->lock, false);
		
		if (timeout->ticks < sum + target->ticks) {
			irq_spinlock_unlock(&target->lock, false);
			break;
		}
		
		sum += target->ticks;
		irq_spinlock_unlock(&target->lock, false);
	}
	
	/* Avoid using cur->prev directly */
	link_t *prev = cur->prev;
	list_prepend(&timeout->link, prev);
	
	/*
	 * Adjust timeout->ticks according to ticks
	 * accumulated in target's predecessors.
	 */
	timeout->ticks -= sum;
	
	/*
	 * Decrease ticks of timeout's immediate succesor by timeout->ticks.
	 */
	if (cur != &CPU->timeout_active_head) {
		irq_spinlock_lock(&target->lock, false);
		target->ticks -= timeout->ticks;
		irq_spinlock_unlock(&target->lock, false);
	}
	
	irq_spinlock_unlock(&timeout->lock, false);
	irq_spinlock_unlock(&CPU->timeoutlock, true);
}

/** Unregister timeout
 *
 * Remove timeout from timeout list.
 *
 * @param timeout Timeout to unregister.
 *
 * @return True on success, false on failure.
 *
 */
bool timeout_unregister(timeout_t *timeout)
{
	DEADLOCK_PROBE_INIT(p_tolock);
	
grab_locks:
	irq_spinlock_lock(&timeout->lock, true);
	if (!timeout->cpu) {
		irq_spinlock_unlock(&timeout->lock, true);
		return false;
	}
	
	if (!irq_spinlock_trylock(&timeout->cpu->timeoutlock)) {
		irq_spinlock_unlock(&timeout->lock, true);
		DEADLOCK_PROBE(p_tolock, DEADLOCK_THRESHOLD);
		goto grab_locks;
	}
	
	/*
	 * Now we know for sure that timeout hasn't been activated yet
	 * and is lurking in timeout->cpu->timeout_active_head queue.
	 */
	
	link_t *cur = timeout->link.next;
	if (cur != &timeout->cpu->timeout_active_head) {
		timeout_t *tmp = list_get_instance(cur, timeout_t, link);
		irq_spinlock_lock(&tmp->lock, false);
		tmp->ticks += timeout->ticks;
		irq_spinlock_unlock(&tmp->lock, false);
	}
	
	list_remove(&timeout->link);
	irq_spinlock_unlock(&timeout->cpu->timeoutlock, false);
	
	timeout_reinitialize(timeout);
	irq_spinlock_unlock(&timeout->lock, true);
	
	return true;
}

/** @}
 */