/**
* hwspin_lock_request() - request an hwspinlock
*
* This function should be called by users of the hwspinlock device,
* in order to dynamically assign them an unused hwspinlock.
* Usually the user of this lock will then have to communicate the lock's id
* to the remote core before it can be used for synchronization (to get the
* id of a given hwlock, use hwspin_lock_get_id()).
*
* Should be called from a process context (might sleep)
*
* Returns the address of the assigned hwspinlock, or NULL on error
*/
struct hwspinlock *hwspin_lock_request(void)
{
struct hwspinlock *hwlock;
int ret;
mutex_lock(&hwspinlock_tree_lock);
/* look for an unused lock */
ret = radix_tree_gang_lookup_tag(&hwspinlock_tree, (void **)&hwlock,
0, 1, HWSPINLOCK_UNUSED);
if (ret == 0) {
pr_warn("a free hwspinlock is not available\n");
hwlock = NULL;
goto out;
}
/* sanity check that should never fail */
WARN_ON(ret > 1);
/* mark as used and power up */
ret = __hwspin_lock_request(hwlock);
if (ret < 0)
hwlock = NULL;
out:
mutex_unlock(&hwspinlock_tree_lock);
return hwlock;
}
/**
* hwspin_lock_request_specific() - request for a specific hwspinlock
* @id: index of the specific hwspinlock that is requested
*
* This function should be called by users of the hwspinlock module,
* in order to assign them a specific hwspinlock.
* Usually early board code will be calling this function in order to
* reserve specific hwspinlock ids for predefined purposes.
*
* Should be called from a process context (might sleep)
*
* Returns the address of the assigned hwspinlock, or NULL on error
*/
struct hwspinlock *hwspin_lock_request_specific(unsigned int id)
{
struct hwspinlock *hwlock;
int ret;
mutex_lock(&hwspinlock_tree_lock);
/* make sure this hwspinlock exists */
hwlock = radix_tree_lookup(&hwspinlock_tree, id);
if (!hwlock) {
pr_warn("hwspinlock %u does not exist\n", id);
goto out;
}
/* sanity check (this shouldn't happen) */
WARN_ON(hwlock_to_id(hwlock) != id);
/* make sure this hwspinlock is unused */
ret = radix_tree_tag_get(&hwspinlock_tree, id, HWSPINLOCK_UNUSED);
if (ret == 0) {
pr_warn("hwspinlock %u is already in use\n", id);
hwlock = NULL;
goto out;
}
/* mark as used and power up */
ret = __hwspin_lock_request(hwlock);
if (ret < 0)
hwlock = NULL;
out:
mutex_unlock(&hwspinlock_tree_lock);
return hwlock;
}
/**
* hwspin_lock_request() - request an hwspinlock
* @lock_type: User to decide to use mutex or spinlocks
* 1 to use mutex & 0 to use spinlock. If mutex is used, hwspinlock APIs can
* be called from context that sleeps but cannot be called from interrupt
* context. If spinlock is used the APIs can be called from any context but
* the calling context cannot sleep.
*
* This function should be called by users of the hwspinlock device,
* in order to dynamically assign them an unused hwspinlock.
* Usually the user of this lock will then have to communicate the lock's id
* to the remote core before it can be used for synchronization (to get the
* id of a given hwlock, use hwspin_lock_get_id()).
*
* Should be called from a process context (might sleep)
*
* Returns the address of the assigned hwspinlock, or NULL on error
*/
struct hwspinlock *hwspin_lock_request(enum lock_type l)
{
struct hwspinlock *hwlock;
int ret;
mutex_lock(&hwspinlock_tree_lock);
/* look for an unused lock */
ret = radix_tree_gang_lookup_tag(&hwspinlock_tree, (void **)&hwlock,
0, 1, HWSPINLOCK_UNUSED);
if (ret == 0) {
pr_warn("a free hwspinlock is not available\n");
hwlock = NULL;
goto out;
}
/* sanity check that should never fail */
WARN_ON(ret > 1);
/* mark as used and power up */
ret = __hwspin_lock_request(hwlock);
if (ret < 0) {
hwlock = NULL;
} else {
if (l == USE_MUTEX_LOCK)
mutex_init(&hwlock->sw_l.mlock);
else
spin_lock_init(&hwlock->sw_l.slock);
hwlock->tlock = l;
}
out:
mutex_unlock(&hwspinlock_tree_lock);
return hwlock;
}
