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
126/**
127 * intel_wakeref_put_flags: Release the wakeref
128 * @wf: the wakeref
129 * @flags: control flags
130 *
131 * Release our hold on the wakeref. When there are no more users,
132 * the runtime pm wakeref will be released after the @fn callback is called
133 * underneath the wakeref mutex.
134 *
135 * Note that @fn is allowed to fail, in which case the runtime-pm wakeref
136 * is retained and an error reported.
137 *
138 * Returns: 0 if the wakeref was released successfully, or a negative error
139 * code otherwise.
140 */
141static inline void
142__intel_wakeref_put(struct intel_wakeref *wf, unsigned long flags)
143#define INTEL_WAKEREF_PUT_ASYNC BIT(INTEL_WAKEREF_PUT_ASYNC_BIT)
144#define INTEL_WAKEREF_PUT_DELAY \
145	GENMASK(BITS_PER_LONG - 1, __INTEL_WAKEREF_PUT_LAST_BIT__)
146{
147	INTEL_WAKEREF_BUG_ON(atomic_read(&wf->count) <= 0);
148	if (unlikely(!atomic_add_unless(&wf->count, -1, 1)))
149		__intel_wakeref_put_last(wf, flags);
150}
151
152static inline void
153intel_wakeref_put(struct intel_wakeref *wf)
154{
155	might_sleep();
156	__intel_wakeref_put(wf, 0);
157}
158
159static inline void
160intel_wakeref_put_async(struct intel_wakeref *wf)
161{
162	__intel_wakeref_put(wf, INTEL_WAKEREF_PUT_ASYNC);
163}
164
165static inline void
166intel_wakeref_put_delay(struct intel_wakeref *wf, unsigned long delay)
167{
168	__intel_wakeref_put(wf,
169			    INTEL_WAKEREF_PUT_ASYNC |
170			    FIELD_PREP(INTEL_WAKEREF_PUT_DELAY, delay));
171}
172
173/**
174 * intel_wakeref_lock: Lock the wakeref (mutex)
175 * @wf: the wakeref
176 *
177 * Locks the wakeref to prevent it being acquired or released. New users
178 * can still adjust the counter, but the wakeref itself (and callback)
179 * cannot be acquired or released.
180 */
181static inline void
182intel_wakeref_lock(struct intel_wakeref *wf)
183	__acquires(wf->mutex)
184{
185	mutex_lock(&wf->mutex);
186}
187
188/**
189 * intel_wakeref_unlock: Unlock the wakeref
190 * @wf: the wakeref
191 *
192 * Releases a previously acquired intel_wakeref_lock().
193 */
194static inline void
195intel_wakeref_unlock(struct intel_wakeref *wf)
196	__releases(wf->mutex)
197{
198	mutex_unlock(&wf->mutex);
199}
200
201/**
202 * intel_wakeref_unlock_wait: Wait until the active callback is complete
203 * @wf: the wakeref
204 *
205 * Waits for the active callback (under the @wf->mutex or another CPU) is
206 * complete.
207 */
208static inline void
209intel_wakeref_unlock_wait(struct intel_wakeref *wf)
210{
211	mutex_lock(&wf->mutex);
212	mutex_unlock(&wf->mutex);
213	flush_delayed_work(&wf->work);
214}
215
216/**
217 * intel_wakeref_is_active: Query whether the wakeref is currently held
218 * @wf: the wakeref
219 *
220 * Returns: true if the wakeref is currently held.
221 */
222static inline bool
223intel_wakeref_is_active(const struct intel_wakeref *wf)
224{
225	return READ_ONCE(wf->wakeref);
226}
227
228/**
229 * __intel_wakeref_defer_park: Defer the current park callback
230 * @wf: the wakeref
231 */
232static inline void
233__intel_wakeref_defer_park(struct intel_wakeref *wf)
234{
235	lockdep_assert_held(&wf->mutex);
236	INTEL_WAKEREF_BUG_ON(atomic_read(&wf->count));
237	atomic_set_release(&wf->count, 1);
238}
239
240/**
241 * intel_wakeref_wait_for_idle: Wait until the wakeref is idle
242 * @wf: the wakeref
243 *
244 * Wait for the earlier asynchronous release of the wakeref. Note
245 * this will wait for any third party as well, so make sure you only wait
246 * when you have control over the wakeref and trust no one else is acquiring
247 * it.
248 *
249 * Return: 0 on success, error code if killed.
250 */
251int intel_wakeref_wait_for_idle(struct intel_wakeref *wf);
252
253struct intel_wakeref_auto {
254	struct intel_runtime_pm *rpm;
255	struct timer_list timer;
256	intel_wakeref_t wakeref;
257	spinlock_t lock;
258	refcount_t count;
259};
260
261/**
262 * intel_wakeref_auto: Delay the runtime-pm autosuspend
263 * @wf: the wakeref
264 * @timeout: relative timeout in jiffies
265 *
266 * The runtime-pm core uses a suspend delay after the last wakeref
267 * is released before triggering runtime suspend of the device. That
268 * delay is configurable via sysfs with little regard to the device
269 * characteristics. Instead, we want to tune the autosuspend based on our
270 * HW knowledge. intel_wakeref_auto() delays the sleep by the supplied
271 * timeout.
272 *
273 * Pass @timeout = 0 to cancel a previous autosuspend by executing the
274 * suspend immediately.
275 */
276void intel_wakeref_auto(struct intel_wakeref_auto *wf, unsigned long timeout);
277
278void intel_wakeref_auto_init(struct intel_wakeref_auto *wf,
279			     struct intel_runtime_pm *rpm);
280void intel_wakeref_auto_fini(struct intel_wakeref_auto *wf);
281
282#endif /* INTEL_WAKEREF_H */