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/*
* SPDX-License-Identifier: MIT
*
* Copyright © 2019 Intel Corporation
*/
#include <linux/wait_bit.h>
#include "intel_runtime_pm.h"
#include "intel_wakeref.h"
static void rpm_get(struct intel_wakeref *wf)
{
wf->wakeref = intel_runtime_pm_get(wf->rpm);
}
static void rpm_put(struct intel_wakeref *wf)
{
intel_wakeref_t wakeref = fetch_and_zero(&wf->wakeref);
intel_runtime_pm_put(wf->rpm, wakeref);
INTEL_WAKEREF_BUG_ON(!wakeref);
}
int __intel_wakeref_get_first(struct intel_wakeref *wf)
{
/*
* Treat get/put as different subclasses, as we may need to run
* the put callback from under the shrinker and do not want to
* cross-contanimate that callback with any extra work performed
* upon acquiring the wakeref.
*/
mutex_lock_nested(&wf->mutex, SINGLE_DEPTH_NESTING);
if (!atomic_read(&wf->count)) {
int err;
rpm_get(wf);
err = wf->ops->get(wf);
if (unlikely(err)) {
rpm_put(wf);
mutex_unlock(&wf->mutex);
return err;
}
smp_mb__before_atomic(); /* release wf->count */
}
atomic_inc(&wf->count);
mutex_unlock(&wf->mutex);
INTEL_WAKEREF_BUG_ON(atomic_read(&wf->count) <= 0);
return 0;
}
static void ____intel_wakeref_put_last(struct intel_wakeref *wf)
{
if (!atomic_dec_and_test(&wf->count))
goto unlock;
/* ops->put() must reschedule its own release on error/deferral */
if (likely(!wf->ops->put(wf))) {
rpm_put(wf);
wake_up_var(&wf->wakeref);
}
unlock:
mutex_unlock(&wf->mutex);
}
void __intel_wakeref_put_last(struct intel_wakeref *wf)
{
INTEL_WAKEREF_BUG_ON(work_pending(&wf->work));
/* Assume we are not in process context and so cannot sleep. */
if (wf->ops->flags & INTEL_WAKEREF_PUT_ASYNC ||
!mutex_trylock(&wf->mutex)) {
schedule_work(&wf->work);
return;
}
____intel_wakeref_put_last(wf);
}
static void __intel_wakeref_put_work(struct work_struct *wrk)
{
struct intel_wakeref *wf = container_of(wrk, typeof(*wf), work);
if (atomic_add_unless(&wf->count, -1, 1))
return;
mutex_lock(&wf->mutex);
____intel_wakeref_put_last(wf);
}
void __intel_wakeref_init(struct intel_wakeref *wf,
struct intel_runtime_pm *rpm,
const struct intel_wakeref_ops *ops,
struct lock_class_key *key)
{
wf->rpm = rpm;
wf->ops = ops;
__mutex_init(&wf->mutex, "wakeref", key);
atomic_set(&wf->count, 0);
wf->wakeref = 0;
INIT_WORK(&wf->work, __intel_wakeref_put_work);
}
int intel_wakeref_wait_for_idle(struct intel_wakeref *wf)
{
return wait_var_event_killable(&wf->wakeref,
!intel_wakeref_is_active(wf));
}
static void wakeref_auto_timeout(struct timer_list *t)
{
struct intel_wakeref_auto *wf = from_timer(wf, t, timer);
intel_wakeref_t wakeref;
unsigned long flags;
if (!refcount_dec_and_lock_irqsave(&wf->count, &wf->lock, &flags))
return;
wakeref = fetch_and_zero(&wf->wakeref);
spin_unlock_irqrestore(&wf->lock, flags);
intel_runtime_pm_put(wf->rpm, wakeref);
}
void intel_wakeref_auto_init(struct intel_wakeref_auto *wf,
struct intel_runtime_pm *rpm)
{
spin_lock_init(&wf->lock);
timer_setup(&wf->timer, wakeref_auto_timeout, 0);
refcount_set(&wf->count, 0);
wf->wakeref = 0;
wf->rpm = rpm;
}
void intel_wakeref_auto(struct intel_wakeref_auto *wf, unsigned long timeout)
{
unsigned long flags;
if (!timeout) {
if (del_timer_sync(&wf->timer))
wakeref_auto_timeout(&wf->timer);
return;
}
/* Our mission is that we only extend an already active wakeref */
assert_rpm_wakelock_held(wf->rpm);
if (!refcount_inc_not_zero(&wf->count)) {
spin_lock_irqsave(&wf->lock, flags);
if (!refcount_inc_not_zero(&wf->count)) {
INTEL_WAKEREF_BUG_ON(wf->wakeref);
wf->wakeref = intel_runtime_pm_get_if_in_use(wf->rpm);
refcount_set(&wf->count, 1);
}
spin_unlock_irqrestore(&wf->lock, flags);
}
/*
* If we extend a pending timer, we will only get a single timer
* callback and so need to cancel the local inc by running the
* elided callback to keep the wf->count balanced.
*/
if (mod_timer(&wf->timer, jiffies + timeout))
wakeref_auto_timeout(&wf->timer);
}
void intel_wakeref_auto_fini(struct intel_wakeref_auto *wf)
{
intel_wakeref_auto(wf, 0);
INTEL_WAKEREF_BUG_ON(wf->wakeref);
}
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