intel_wakeref.h

  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/ref_tracker.h>
 17#include <linux/timer.h>
 18#include <linux/workqueue.h>
 19
 20struct drm_printer;
 21struct intel_runtime_pm;
 22struct intel_wakeref;
 23
 24typedef struct ref_tracker *intel_wakeref_t;
 25
 26#define INTEL_REFTRACK_DEAD_COUNT 16
 27#define INTEL_REFTRACK_PRINT_LIMIT 16
 28
 29#if IS_ENABLED(CONFIG_DRM_I915_DEBUG)
 30#define INTEL_WAKEREF_BUG_ON(expr) BUG_ON(expr)
 31#else
 32#define INTEL_WAKEREF_BUG_ON(expr) BUILD_BUG_ON_INVALID(expr)
 33#endif
 34
 35struct intel_wakeref_ops {
 36	int (*get)(struct intel_wakeref *wf);
 37	int (*put)(struct intel_wakeref *wf);
 38};
 39
 40struct intel_wakeref {
 41	atomic_t count;
 42	struct mutex mutex;
 43
 44	intel_wakeref_t wakeref;
 45
 46	struct drm_i915_private *i915;
 47	const struct intel_wakeref_ops *ops;
 48
 49	struct delayed_work work;
 50
 51#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_WAKEREF)
 52	struct ref_tracker_dir debug;
 53#endif
 54};
 55
 56struct intel_wakeref_lockclass {
 57	struct lock_class_key mutex;
 58	struct lock_class_key work;
 59};
 60
 61void __intel_wakeref_init(struct intel_wakeref *wf,
 62			  struct drm_i915_private *i915,
 63			  const struct intel_wakeref_ops *ops,
 64			  struct intel_wakeref_lockclass *key,
 65			  const char *name);
 66#define intel_wakeref_init(wf, i915, ops, name) do {			\
 67	static struct intel_wakeref_lockclass __key;			\
 68									\
 69	__intel_wakeref_init((wf), (i915), (ops), &__key, name);	\
 70} while (0)
 71
 72int __intel_wakeref_get_first(struct intel_wakeref *wf);
 73void __intel_wakeref_put_last(struct intel_wakeref *wf, unsigned long flags);
 74
 75/**
 76 * intel_wakeref_get: Acquire the wakeref
 77 * @wf: the wakeref
 78 *
 79 * Acquire a hold on the wakeref. The first user to do so, will acquire
 80 * the runtime pm wakeref and then call the intel_wakeref_ops->get()
 81 * underneath the wakeref mutex.
 82 *
 83 * Note that intel_wakeref_ops->get() is allowed to fail, in which case
 84 * the runtime-pm wakeref will be released and the acquisition unwound,
 85 * and an error reported.
 86 *
 87 * Returns: 0 if the wakeref was acquired successfully, or a negative error
 88 * code otherwise.
 89 */
 90static inline int
 91intel_wakeref_get(struct intel_wakeref *wf)
 92{
 93	might_sleep();
 94	if (unlikely(!atomic_inc_not_zero(&wf->count)))
 95		return __intel_wakeref_get_first(wf);
 96
 97	return 0;
 98}
 99
100/**
101 * __intel_wakeref_get: Acquire the wakeref, again
102 * @wf: the wakeref
103 *
104 * Increment the wakeref counter, only valid if it is already held by
105 * the caller.
106 *
107 * See intel_wakeref_get().
108 */
109static inline void
110__intel_wakeref_get(struct intel_wakeref *wf)
111{
112	INTEL_WAKEREF_BUG_ON(atomic_read(&wf->count) <= 0);
113	atomic_inc(&wf->count);
114}
115
116/**
117 * intel_wakeref_get_if_active: Acquire the wakeref
118 * @wf: the wakeref
119 *
120 * Acquire a hold on the wakeref, but only if the wakeref is already
121 * active.
122 *
123 * Returns: true if the wakeref was acquired, false otherwise.
124 */
125static inline bool
126intel_wakeref_get_if_active(struct intel_wakeref *wf)
127{
128	return atomic_inc_not_zero(&wf->count);
129}
130
131static inline void
132intel_wakeref_might_get(struct intel_wakeref *wf)
133{
134	might_lock(&wf->mutex);
135}
136
137/* flags for __intel_wakeref_put() and __intel_wakeref_put_last */
138#define INTEL_WAKEREF_PUT_ASYNC		BIT(0)
139#define INTEL_WAKEREF_PUT_DELAY_MASK	GENMASK(BITS_PER_LONG - 1, 1)
140
141/**
142 * __intel_wakeref_put: Release the wakeref
143 * @wf: the wakeref
144 * @flags: control flags
145 *
146 * Release our hold on the wakeref. When there are no more users,
147 * the runtime pm wakeref will be released after the intel_wakeref_ops->put()
148 * callback is called underneath the wakeref mutex.
149 *
150 * Note that intel_wakeref_ops->put() is allowed to fail, in which case the
151 * runtime-pm wakeref is retained.
152 *
153 */
154static inline void
155__intel_wakeref_put(struct intel_wakeref *wf, unsigned long flags)
156{
157	INTEL_WAKEREF_BUG_ON(atomic_read(&wf->count) <= 0);
158	if (unlikely(!atomic_add_unless(&wf->count, -1, 1)))
159		__intel_wakeref_put_last(wf, flags);
160}
161
162static inline void
163intel_wakeref_put(struct intel_wakeref *wf)
164{
165	might_sleep();
166	__intel_wakeref_put(wf, 0);
167}
168
169static inline void
170intel_wakeref_put_async(struct intel_wakeref *wf)
171{
172	__intel_wakeref_put(wf, INTEL_WAKEREF_PUT_ASYNC);
173}
174
175static inline void
176intel_wakeref_put_delay(struct intel_wakeref *wf, unsigned long delay)
177{
178	__intel_wakeref_put(wf,
179			    INTEL_WAKEREF_PUT_ASYNC |
180			    FIELD_PREP(INTEL_WAKEREF_PUT_DELAY_MASK, delay));
181}
182
183static inline void
184intel_wakeref_might_put(struct intel_wakeref *wf)
185{
186	might_lock(&wf->mutex);
187}
188
189/**
190 * intel_wakeref_lock: Lock the wakeref (mutex)
191 * @wf: the wakeref
192 *
193 * Locks the wakeref to prevent it being acquired or released. New users
194 * can still adjust the counter, but the wakeref itself (and callback)
195 * cannot be acquired or released.
196 */
197static inline void
198intel_wakeref_lock(struct intel_wakeref *wf)
199	__acquires(wf->mutex)
200{
201	mutex_lock(&wf->mutex);
202}
203
204/**
205 * intel_wakeref_unlock: Unlock the wakeref
206 * @wf: the wakeref
207 *
208 * Releases a previously acquired intel_wakeref_lock().
209 */
210static inline void
211intel_wakeref_unlock(struct intel_wakeref *wf)
212	__releases(wf->mutex)
213{
214	mutex_unlock(&wf->mutex);
215}
216
217/**
218 * intel_wakeref_unlock_wait: Wait until the active callback is complete
219 * @wf: the wakeref
220 *
221 * Waits for the active callback (under the @wf->mutex or another CPU) is
222 * complete.
223 */
224static inline void
225intel_wakeref_unlock_wait(struct intel_wakeref *wf)
226{
227	mutex_lock(&wf->mutex);
228	mutex_unlock(&wf->mutex);
229	flush_delayed_work(&wf->work);
230}
231
232/**
233 * intel_wakeref_is_active: Query whether the wakeref is currently held
234 * @wf: the wakeref
235 *
236 * Returns: true if the wakeref is currently held.
237 */
238static inline bool
239intel_wakeref_is_active(const struct intel_wakeref *wf)
240{
241	return READ_ONCE(wf->wakeref);
242}
243
244/**
245 * __intel_wakeref_defer_park: Defer the current park callback
246 * @wf: the wakeref
247 */
248static inline void
249__intel_wakeref_defer_park(struct intel_wakeref *wf)
250{
251	lockdep_assert_held(&wf->mutex);
252	INTEL_WAKEREF_BUG_ON(atomic_read(&wf->count));
253	atomic_set_release(&wf->count, 1);
254}
255
256/**
257 * intel_wakeref_wait_for_idle: Wait until the wakeref is idle
258 * @wf: the wakeref
259 *
260 * Wait for the earlier asynchronous release of the wakeref. Note
261 * this will wait for any third party as well, so make sure you only wait
262 * when you have control over the wakeref and trust no one else is acquiring
263 * it.
264 *
265 * Return: 0 on success, error code if killed.
266 */
267int intel_wakeref_wait_for_idle(struct intel_wakeref *wf);
268
269#define INTEL_WAKEREF_DEF ERR_PTR(-ENOENT)
270
271static inline intel_wakeref_t intel_ref_tracker_alloc(struct ref_tracker_dir *dir)
272{
273	struct ref_tracker *user = NULL;
274
275	ref_tracker_alloc(dir, &user, GFP_NOWAIT);
276
277	return user ?: INTEL_WAKEREF_DEF;
278}
279
280static inline void intel_ref_tracker_free(struct ref_tracker_dir *dir,
281					  intel_wakeref_t wakeref)
282{
283	if (wakeref == INTEL_WAKEREF_DEF)
284		wakeref = NULL;
285
286	if (WARN_ON(IS_ERR(wakeref)))
287		return;
288
289	ref_tracker_free(dir, &wakeref);
290}
291
292void intel_ref_tracker_show(struct ref_tracker_dir *dir,
293			    struct drm_printer *p);
294
295#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_WAKEREF)
296
297static inline intel_wakeref_t intel_wakeref_track(struct intel_wakeref *wf)
298{
299	return intel_ref_tracker_alloc(&wf->debug);
300}
301
302static inline void intel_wakeref_untrack(struct intel_wakeref *wf,
303					 intel_wakeref_t handle)
304{
305	intel_ref_tracker_free(&wf->debug, handle);
306}
307
308#else
309
310static inline intel_wakeref_t intel_wakeref_track(struct intel_wakeref *wf)
311{
312	return INTEL_WAKEREF_DEF;
313}
314
315static inline void intel_wakeref_untrack(struct intel_wakeref *wf,
316					 intel_wakeref_t handle)
317{
318}
319
320#endif
321
322struct intel_wakeref_auto {
323	struct drm_i915_private *i915;
324	struct timer_list timer;
325	intel_wakeref_t wakeref;
326	spinlock_t lock;
327	refcount_t count;
328};
329
330/**
331 * intel_wakeref_auto: Delay the runtime-pm autosuspend
332 * @wf: the wakeref
333 * @timeout: relative timeout in jiffies
334 *
335 * The runtime-pm core uses a suspend delay after the last wakeref
336 * is released before triggering runtime suspend of the device. That
337 * delay is configurable via sysfs with little regard to the device
338 * characteristics. Instead, we want to tune the autosuspend based on our
339 * HW knowledge. intel_wakeref_auto() delays the sleep by the supplied
340 * timeout.
341 *
342 * Pass @timeout = 0 to cancel a previous autosuspend by executing the
343 * suspend immediately.
344 */
345void intel_wakeref_auto(struct intel_wakeref_auto *wf, unsigned long timeout);
346
347void intel_wakeref_auto_init(struct intel_wakeref_auto *wf,
348			     struct drm_i915_private *i915);
349void intel_wakeref_auto_fini(struct intel_wakeref_auto *wf);
350
351#endif /* INTEL_WAKEREF_H */