/*
* Copyright (C) 2005 Martin Decky
* 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.
*/
#include <arch/mm/asid.h>
#include <synch/spinlock.h>
#include <arch.h>
#include <debug.h>
#define ASIDS 256
static spinlock_t asid_usage_lock;
static count_t asid_usage[ASIDS]; /**< Usage tracking array for ASIDs */
/** Get ASID
*
* Get the least used ASID.
*
* @return ASID
*/
asid_t asid_get(void)
{
pri_t pri;
int i, j;
count_t min;
min = (unsigned) -1;
pri = cpu_priority_high();
spinlock_lock(&asid_usage_lock);
for (i=0, j = 0; (i<ASIDS); i++) {
if (asid_usage[i] < min) {
j = i;
min = asid_usage[i];
if (!min)
break;
}
}
asid_usage[i]++;
spinlock_unlock(&asid_usage_lock);
cpu_priority_restore(pri);
return i;
}
/** Release ASID
*
* Release ASID by decrementing its usage count.
*
* @param asid ASID.
*/
void asid_put(asid_t asid)
{
pri_t pri;
pri = cpu_priority_high();
spinlock_lock(&asid_usage_lock);
ASSERT(asid_usage[asid] > 0);
asid_usage[asid]--;
spinlock_unlock(&asid_usage_lock);
cpu_priority_restore(pri);
}