1/*
  2 * SPDX-License-Identifier: MIT
  3 *
  4 * Copyright © 2019 Intel Corporation
  5 */
  6
  7#ifndef INTEL_WAKEREF_H
  8#define INTEL_WAKEREF_H
  9
 10#include <linux/atomic.h>
 11#include <linux/bits.h>
 12#include <linux/mutex.h>
 13#include <linux/refcount.h>
 14#include <linux/stackdepot.h>
 15#include <linux/timer.h>
 16#include <linux/workqueue.h>
 17
 18#if IS_ENABLED(CONFIG_DRM_I915_DEBUG)
 19#define INTEL_WAKEREF_BUG_ON(expr) BUG_ON(expr)
 20#else
 21#define INTEL_WAKEREF_BUG_ON(expr) BUILD_BUG_ON_INVALID(expr)
 22#endif
 23
 24struct intel_runtime_pm;
 25struct intel_wakeref;
 26
 27typedef depot_stack_handle_t intel_wakeref_t;
 28
 29struct intel_wakeref_ops {
 30	int (*get)(struct intel_wakeref *wf);
 31	int (*put)(struct intel_wakeref *wf);
 32
 33	unsigned long flags;
 34#define INTEL_WAKEREF_PUT_ASYNC BIT(0)
 35};
 36
 37struct intel_wakeref {
 38	atomic_t count;
 39	struct mutex mutex;
 40
 41	intel_wakeref_t wakeref;
 42
 43	struct intel_runtime_pm *rpm;
 44	const struct intel_wakeref_ops *ops;
 45
 46	struct work_struct work;
 47};
 48
 49void __intel_wakeref_init(struct intel_wakeref *wf,
 50			  struct intel_runtime_pm *rpm,
 51			  const struct intel_wakeref_ops *ops,
 52			  struct lock_class_key *key);
 53#define intel_wakeref_init(wf, rpm, ops) do {				\
 54	static struct lock_class_key __key;				\
 55									\
 56	__intel_wakeref_init((wf), (rpm), (ops), &__key);		\
 57} while (0)
 58
 59int __intel_wakeref_get_first(struct intel_wakeref *wf);
 60void __intel_wakeref_put_last(struct intel_wakeref *wf);
 61
 62/**
 63 * intel_wakeref_get: Acquire the wakeref
 64 * @i915: the drm_i915_private device
 65 * @wf: the wakeref
 66 * @fn: callback for acquired the wakeref, called only on first acquire.
 67 *
 68 * Acquire a hold on the wakeref. The first user to do so, will acquire
 69 * the runtime pm wakeref and then call the @fn underneath the wakeref
 70 * mutex.
 71 *
 72 * Note that @fn is allowed to fail, in which case the runtime-pm wakeref
 73 * will be released and the acquisition unwound, and an error reported.
 74 *
 75 * Returns: 0 if the wakeref was acquired successfully, or a negative error
 76 * code otherwise.
 77 */
 78static inline int
 79intel_wakeref_get(struct intel_wakeref *wf)
 80{
 81	if (unlikely(!atomic_inc_not_zero(&wf->count)))
 82		return __intel_wakeref_get_first(wf);
 83
 84	return 0;
 85}
 86
 87/**
 88 * intel_wakeref_get_if_in_use: Acquire the wakeref
 89 * @wf: the wakeref
 90 *
 91 * Acquire a hold on the wakeref, but only if the wakeref is already
 92 * active.
 93 *
 94 * Returns: true if the wakeref was acquired, false otherwise.
 95 */
 96static inline bool
 97intel_wakeref_get_if_active(struct intel_wakeref *wf)
 98{
 99	return atomic_inc_not_zero(&wf->count);
100}
101
102/**
103 * intel_wakeref_put: Release the wakeref
104 * @i915: the drm_i915_private device
105 * @wf: the wakeref
106 * @fn: callback for releasing the wakeref, called only on final release.
107 *
108 * Release our hold on the wakeref. When there are no more users,
109 * the runtime pm wakeref will be released after the @fn callback is called
110 * underneath the wakeref mutex.
111 *
112 * Note that @fn is allowed to fail, in which case the runtime-pm wakeref
113 * is retained and an error reported.
114 *
115 * Returns: 0 if the wakeref was released successfully, or a negative error
116 * code otherwise.
117 */
118static inline void
119intel_wakeref_put(struct intel_wakeref *wf)
120{
121	INTEL_WAKEREF_BUG_ON(atomic_read(&wf->count) <= 0);
122	if (unlikely(!atomic_add_unless(&wf->count, -1, 1)))
123		__intel_wakeref_put_last(wf);
124}
125
126/**
127 * intel_wakeref_lock: Lock the wakeref (mutex)
128 * @wf: the wakeref
129 *
130 * Locks the wakeref to prevent it being acquired or released. New users
131 * can still adjust the counter, but the wakeref itself (and callback)
132 * cannot be acquired or released.
133 */
134static inline void
135intel_wakeref_lock(struct intel_wakeref *wf)
136	__acquires(wf->mutex)
137{
138	mutex_lock(&wf->mutex);
139}
140
141/**
142 * intel_wakeref_unlock: Unlock the wakeref
143 * @wf: the wakeref
144 *
145 * Releases a previously acquired intel_wakeref_lock().
146 */
147static inline void
148intel_wakeref_unlock(struct intel_wakeref *wf)
149	__releases(wf->mutex)
150{
151	mutex_unlock(&wf->mutex);
152}
153
154/**
155 * intel_wakeref_is_active: Query whether the wakeref is currently held
156 * @wf: the wakeref
157 *
158 * Returns: true if the wakeref is currently held.
159 */
160static inline bool
161intel_wakeref_is_active(const struct intel_wakeref *wf)
162{
163	return READ_ONCE(wf->wakeref);
164}
165
166/**
167 * __intel_wakeref_defer_park: Defer the current park callback
168 * @wf: the wakeref
169 */
170static inline void
171__intel_wakeref_defer_park(struct intel_wakeref *wf)
172{
173	INTEL_WAKEREF_BUG_ON(atomic_read(&wf->count));
174	atomic_set_release(&wf->count, 1);
175}
176
177/**
178 * intel_wakeref_wait_for_idle: Wait until the wakeref is idle
179 * @wf: the wakeref
180 *
181 * Wait for the earlier asynchronous release of the wakeref. Note
182 * this will wait for any third party as well, so make sure you only wait
183 * when you have control over the wakeref and trust no one else is acquiring
184 * it.
185 *
186 * Return: 0 on success, error code if killed.
187 */
188int intel_wakeref_wait_for_idle(struct intel_wakeref *wf);
189
190struct intel_wakeref_auto {
191	struct intel_runtime_pm *rpm;
192	struct timer_list timer;
193	intel_wakeref_t wakeref;
194	spinlock_t lock;
195	refcount_t count;
196};
197
198/**
199 * intel_wakeref_auto: Delay the runtime-pm autosuspend
200 * @wf: the wakeref
201 * @timeout: relative timeout in jiffies
202 *
203 * The runtime-pm core uses a suspend delay after the last wakeref
204 * is released before triggering runtime suspend of the device. That
205 * delay is configurable via sysfs with little regard to the device
206 * characteristics. Instead, we want to tune the autosuspend based on our
207 * HW knowledge. intel_wakeref_auto() delays the sleep by the supplied
208 * timeout.
209 *
210 * Pass @timeout = 0 to cancel a previous autosuspend by executing the
211 * suspend immediately.
212 */
213void intel_wakeref_auto(struct intel_wakeref_auto *wf, unsigned long timeout);
214
215void intel_wakeref_auto_init(struct intel_wakeref_auto *wf,
216			     struct intel_runtime_pm *rpm);
217void intel_wakeref_auto_fini(struct intel_wakeref_auto *wf);
218
219#endif /* INTEL_WAKEREF_H */