/*
* SPDX-License-Identifier: MIT
*
* Copyright © 2019 Intel Corporation
*/
#ifndef INTEL_WAKEREF_H
#define INTEL_WAKEREF_H
#include <linux/atomic.h>
#include <linux/mutex.h>
#include <linux/stackdepot.h>
struct drm_i915_private;
typedef depot_stack_handle_t intel_wakeref_t;
struct intel_wakeref {
atomic_t count;
struct mutex mutex;
intel_wakeref_t wakeref;
};
void __intel_wakeref_init(struct intel_wakeref *wf,
struct lock_class_key *key);
#define intel_wakeref_init(wf) do { \
static struct lock_class_key __key; \
\
__intel_wakeref_init((wf), &__key); \
} while (0)
int __intel_wakeref_get_first(struct drm_i915_private *i915,
struct intel_wakeref *wf,
int (*fn)(struct intel_wakeref *wf));
int __intel_wakeref_put_last(struct drm_i915_private *i915,
struct intel_wakeref *wf,
int (*fn)(struct intel_wakeref *wf));
/**
* intel_wakeref_get: Acquire the wakeref
* @i915: the drm_i915_private device
* @wf: the wakeref
* @fn: callback for acquired the wakeref, called only on first acquire.
*
* Acquire a hold on the wakeref. The first user to do so, will acquire
* the runtime pm wakeref and then call the @fn underneath the wakeref
* mutex.
*
* Note that @fn is allowed to fail, in which case the runtime-pm wakeref
* will be released and the acquisition unwound, and an error reported.
*
* Returns: 0 if the wakeref was acquired successfully, or a negative error
* code otherwise.
*/
static inline int
intel_wakeref_get(struct drm_i915_private *i915,
struct intel_wakeref *wf,
int (*fn)(struct intel_wakeref *wf))
{
if (unlikely(!atomic_inc_not_zero(&wf->count)))
return __intel_wakeref_get_first(i915, wf, fn);
return 0;
}
/**
* intel_wakeref_put: Release the wakeref
* @i915: the drm_i915_private device
* @wf: the wakeref
* @fn: callback for releasing the wakeref, called only on final release.
*
* Release our hold on the wakeref. When there are no more users,
* the runtime pm wakeref will be released after the @fn callback is called
* underneath the wakeref mutex.
*
* Note that @fn is allowed to fail, in which case the runtime-pm wakeref
* is retained and an error reported.
*
* Returns: 0 if the wakeref was released successfully, or a negative error
* code otherwise.
*/
static inline int
intel_wakeref_put(struct drm_i915_private *i915,
struct intel_wakeref *wf,
int (*fn)(struct intel_wakeref *wf))
{
if (atomic_dec_and_mutex_lock(&wf->count, &wf->mutex))
return __intel_wakeref_put_last(i915, wf, fn);
return 0;
}
/**
* intel_wakeref_lock: Lock the wakeref (mutex)
* @wf: the wakeref
*
* Locks the wakeref to prevent it being acquired or released. New users
* can still adjust the counter, but the wakeref itself (and callback)
* cannot be acquired or released.
*/
static inline void
intel_wakeref_lock(struct intel_wakeref *wf)
__acquires(wf->mutex)
{
mutex_lock(&wf->mutex);
}
/**
* intel_wakeref_unlock: Unlock the wakeref
* @wf: the wakeref
*
* Releases a previously acquired intel_wakeref_lock().
*/
static inline void
intel_wakeref_unlock(struct intel_wakeref *wf)
__releases(wf->mutex)
{
mutex_unlock(&wf->mutex);
}
/**
* intel_wakeref_active: Query whether the wakeref is currently held
* @wf: the wakeref
*
* Returns: true if the wakeref is currently held.
*/
static inline bool
intel_wakeref_active(struct intel_wakeref *wf)
{
return atomic_read(&wf->count);
}
#endif /* INTEL_WAKEREF_H */
