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/bitfield.h>
 12#include <linux/bits.h>
 13#include <linux/lockdep.h>
 14#include <linux/mutex.h>
 15#include <linux/refcount.h>
 16#include <linux/stackdepot.h>
 17#include <linux/timer.h>
 18#include <linux/workqueue.h>
 19
 20#if IS_ENABLED(CONFIG_DRM_I915_DEBUG)
 21#define INTEL_WAKEREF_BUG_ON(expr) BUG_ON(expr)
 22#else
 23#define INTEL_WAKEREF_BUG_ON(expr) BUILD_BUG_ON_INVALID(expr)
 24#endif
 25
 26struct intel_runtime_pm;
 27struct intel_wakeref;
 28
 29typedef depot_stack_handle_t intel_wakeref_t;
 30
 31struct intel_wakeref_ops {
 32	int (*get)(struct intel_wakeref *wf);
 33	int (*put)(struct intel_wakeref *wf);
 34};
 35
 36struct intel_wakeref {
 37	atomic_t count;
 38	struct mutex mutex;
 39
 40	intel_wakeref_t wakeref;
 41
 42	struct intel_runtime_pm *rpm;
 43	const struct intel_wakeref_ops *ops;
 44
 45	struct delayed_work work;
 46};
 47
 48struct intel_wakeref_lockclass {
 49	struct lock_class_key mutex;
 50	struct lock_class_key work;
 51};
 52
 53void __intel_wakeref_init(struct intel_wakeref *wf,
 54			  struct intel_runtime_pm *rpm,
 55			  const struct intel_wakeref_ops *ops,
 56			  struct intel_wakeref_lockclass *key);
 57#define intel_wakeref_init(wf, rpm, ops) do {				\
 58	static struct intel_wakeref_lockclass __key;			\
 59									\
 60	__intel_wakeref_init((wf), (rpm), (ops), &__key);		\
 61} while (0)
 62
 63int __intel_wakeref_get_first(struct intel_wakeref *wf);
 64void __intel_wakeref_put_last(struct intel_wakeref *wf, unsigned long flags);
 65
 66/**
 67 * intel_wakeref_get: Acquire the wakeref
 68 * @wf: the wakeref
 69 *
 70 * Acquire a hold on the wakeref. The first user to do so, will acquire
 71 * the runtime pm wakeref and then call the @fn underneath the wakeref
 72 * mutex.
 73 *
 74 * Note that @fn is allowed to fail, in which case the runtime-pm wakeref
 75 * will be released and the acquisition unwound, and an error reported.
 76 *
 77 * Returns: 0 if the wakeref was acquired successfully, or a negative error
 78 * code otherwise.
 79 */
 80static inline int
 81intel_wakeref_get(struct intel_wakeref *wf)
 82{
 83	might_sleep();
 84	if (unlikely(!atomic_inc_not_zero(&wf->count)))
 85		return __intel_wakeref_get_first(wf);
 86
 87	return 0;
 88}
 89
 90/**
 91 * __intel_wakeref_get: Acquire the wakeref, again
 92 * @wf: the wakeref
 93 *
 94 * Increment the wakeref counter, only valid if it is already held by
 95 * the caller.
 96 *
 97 * See intel_wakeref_get().
 98 */
 99static inline void
100__intel_wakeref_get(struct intel_wakeref *wf)
101{
102	INTEL_WAKEREF_BUG_ON(atomic_read(&wf->count) <= 0);
103	atomic_inc(&wf->count);
104}
105
106/**
107 * intel_wakeref_get_if_in_use: Acquire the wakeref
108 * @wf: the wakeref
109 *
110 * Acquire a hold on the wakeref, but only if the wakeref is already
111 * active.
112 *
113 * Returns: true if the wakeref was acquired, false otherwise.
114 */
115static inline bool
116intel_wakeref_get_if_active(struct intel_wakeref *wf)
117{
118	return atomic_inc_not_zero(&wf->count);
119}
120
121enum {
122	INTEL_WAKEREF_PUT_ASYNC_BIT = 0,
123	__INTEL_WAKEREF_PUT_LAST_BIT__
124};
125
126static inline void
127intel_wakeref_might_get(struct intel_wakeref *wf)
128{
129	might_lock(&wf->mutex);
130}
131
132/**
133 * intel_wakeref_put_flags: Release the wakeref
134 * @wf: the wakeref
135 * @flags: control flags
136 *
137 * Release our hold on the wakeref. When there are no more users,
138 * the runtime pm wakeref will be released after the @fn callback is called
139 * underneath the wakeref mutex.
140 *
141 * Note that @fn is allowed to fail, in which case the runtime-pm wakeref
142 * is retained and an error reported.
143 *
144 * Returns: 0 if the wakeref was released successfully, or a negative error
145 * code otherwise.
146 */
147static inline void
148__intel_wakeref_put(struct intel_wakeref *wf, unsigned long flags)
149#define INTEL_WAKEREF_PUT_ASYNC BIT(INTEL_WAKEREF_PUT_ASYNC_BIT)
150#define INTEL_WAKEREF_PUT_DELAY \
151	GENMASK(BITS_PER_LONG - 1, __INTEL_WAKEREF_PUT_LAST_BIT__)
152{
153	INTEL_WAKEREF_BUG_ON(atomic_read(&wf->count) <= 0);
154	if (unlikely(!atomic_add_unless(&wf->count, -1, 1)))
155		__intel_wakeref_put_last(wf, flags);
156}
157
158static inline void
159intel_wakeref_put(struct intel_wakeref *wf)
160{
161	might_sleep();
162	__intel_wakeref_put(wf, 0);
163}
164
165static inline void
166intel_wakeref_put_async(struct intel_wakeref *wf)
167{
168	__intel_wakeref_put(wf, INTEL_WAKEREF_PUT_ASYNC);
169}
170
171static inline void
172intel_wakeref_put_delay(struct intel_wakeref *wf, unsigned long delay)
173{
174	__intel_wakeref_put(wf,
175			    INTEL_WAKEREF_PUT_ASYNC |
176			    FIELD_PREP(INTEL_WAKEREF_PUT_DELAY, delay));
177}
178
179static inline void
180intel_wakeref_might_put(struct intel_wakeref *wf)
181{
182	might_lock(&wf->mutex);
183}
184
185/**
186 * intel_wakeref_lock: Lock the wakeref (mutex)
187 * @wf: the wakeref
188 *
189 * Locks the wakeref to prevent it being acquired or released. New users
190 * can still adjust the counter, but the wakeref itself (and callback)
191 * cannot be acquired or released.
192 */
193static inline void
194intel_wakeref_lock(struct intel_wakeref *wf)
195	__acquires(wf->mutex)
196{
197	mutex_lock(&wf->mutex);
198}
199
200/**
201 * intel_wakeref_unlock: Unlock the wakeref
202 * @wf: the wakeref
203 *
204 * Releases a previously acquired intel_wakeref_lock().
205 */
206static inline void
207intel_wakeref_unlock(struct intel_wakeref *wf)
208	__releases(wf->mutex)
209{
210	mutex_unlock(&wf->mutex);
211}
212
213/**
214 * intel_wakeref_unlock_wait: Wait until the active callback is complete
215 * @wf: the wakeref
216 *
217 * Waits for the active callback (under the @wf->mutex or another CPU) is
218 * complete.
219 */
220static inline void
221intel_wakeref_unlock_wait(struct intel_wakeref *wf)
222{
223	mutex_lock(&wf->mutex);
224	mutex_unlock(&wf->mutex);
225	flush_delayed_work(&wf->work);
226}
227
228/**
229 * intel_wakeref_is_active: Query whether the wakeref is currently held
230 * @wf: the wakeref
231 *
232 * Returns: true if the wakeref is currently held.
233 */
234static inline bool
235intel_wakeref_is_active(const struct intel_wakeref *wf)
236{
237	return READ_ONCE(wf->wakeref);
238}
239
240/**
241 * __intel_wakeref_defer_park: Defer the current park callback
242 * @wf: the wakeref
243 */
244static inline void
245__intel_wakeref_defer_park(struct intel_wakeref *wf)
246{
247	lockdep_assert_held(&wf->mutex);
248	INTEL_WAKEREF_BUG_ON(atomic_read(&wf->count));
249	atomic_set_release(&wf->count, 1);
250}
251
252/**
253 * intel_wakeref_wait_for_idle: Wait until the wakeref is idle
254 * @wf: the wakeref
255 *
256 * Wait for the earlier asynchronous release of the wakeref. Note
257 * this will wait for any third party as well, so make sure you only wait
258 * when you have control over the wakeref and trust no one else is acquiring
259 * it.
260 *
261 * Return: 0 on success, error code if killed.
262 */
263int intel_wakeref_wait_for_idle(struct intel_wakeref *wf);
264
265struct intel_wakeref_auto {
266	struct intel_runtime_pm *rpm;
267	struct timer_list timer;
268	intel_wakeref_t wakeref;
269	spinlock_t lock;
270	refcount_t count;
271};
272
273/**
274 * intel_wakeref_auto: Delay the runtime-pm autosuspend
275 * @wf: the wakeref
276 * @timeout: relative timeout in jiffies
277 *
278 * The runtime-pm core uses a suspend delay after the last wakeref
279 * is released before triggering runtime suspend of the device. That
280 * delay is configurable via sysfs with little regard to the device
281 * characteristics. Instead, we want to tune the autosuspend based on our
282 * HW knowledge. intel_wakeref_auto() delays the sleep by the supplied
283 * timeout.
284 *
285 * Pass @timeout = 0 to cancel a previous autosuspend by executing the
286 * suspend immediately.
287 */
288void intel_wakeref_auto(struct intel_wakeref_auto *wf, unsigned long timeout);
289
290void intel_wakeref_auto_init(struct intel_wakeref_auto *wf,
291			     struct intel_runtime_pm *rpm);
292void intel_wakeref_auto_fini(struct intel_wakeref_auto *wf);
293
294#endif /* INTEL_WAKEREF_H */