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 <drm/drm_print.h>
11
12#include <linux/atomic.h>
13#include <linux/bitfield.h>
14#include <linux/bits.h>
15#include <linux/lockdep.h>
16#include <linux/mutex.h>
17#include <linux/refcount.h>
18#include <linux/ref_tracker.h>
19#include <linux/slab.h>
20#include <linux/stackdepot.h>
21#include <linux/timer.h>
22#include <linux/workqueue.h>
23
24typedef unsigned long 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_runtime_pm;
36struct intel_wakeref;
37
38struct intel_wakeref_ops {
39	int (*get)(struct intel_wakeref *wf);
40	int (*put)(struct intel_wakeref *wf);
41};
42
43struct intel_wakeref {
44	atomic_t count;
45	struct mutex mutex;
46
47	intel_wakeref_t wakeref;
48
49	struct drm_i915_private *i915;
50	const struct intel_wakeref_ops *ops;
51
52	struct delayed_work work;
53
54#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_WAKEREF)
55	struct ref_tracker_dir debug;
56#endif
57};
58
59struct intel_wakeref_lockclass {
60	struct lock_class_key mutex;
61	struct lock_class_key work;
62};
63
64void __intel_wakeref_init(struct intel_wakeref *wf,
65			  struct drm_i915_private *i915,
66			  const struct intel_wakeref_ops *ops,
67			  struct intel_wakeref_lockclass *key,
68			  const char *name);
69#define intel_wakeref_init(wf, i915, ops, name) do {			\
70	static struct intel_wakeref_lockclass __key;			\
71									\
72	__intel_wakeref_init((wf), (i915), (ops), &__key, name);	\
73} while (0)
74
75int __intel_wakeref_get_first(struct intel_wakeref *wf);
76void __intel_wakeref_put_last(struct intel_wakeref *wf, unsigned long flags);
77
78/**
79 * intel_wakeref_get: Acquire the wakeref
80 * @wf: the wakeref
81 *
82 * Acquire a hold on the wakeref. The first user to do so, will acquire
83 * the runtime pm wakeref and then call the intel_wakeref_ops->get()
84 * underneath the wakeref mutex.
85 *
86 * Note that intel_wakeref_ops->get() is allowed to fail, in which case
87 * the runtime-pm wakeref will be released and the acquisition unwound,
88 * and an error reported.
89 *
90 * Returns: 0 if the wakeref was acquired successfully, or a negative error
91 * code otherwise.
92 */
93static inline int
94intel_wakeref_get(struct intel_wakeref *wf)
95{
96	might_sleep();
97	if (unlikely(!atomic_inc_not_zero(&wf->count)))
98		return __intel_wakeref_get_first(wf);
99
100	return 0;
101}
102
103/**
104 * __intel_wakeref_get: Acquire the wakeref, again
105 * @wf: the wakeref
106 *
107 * Increment the wakeref counter, only valid if it is already held by
108 * the caller.
109 *
110 * See intel_wakeref_get().
111 */
112static inline void
113__intel_wakeref_get(struct intel_wakeref *wf)
114{
115	INTEL_WAKEREF_BUG_ON(atomic_read(&wf->count) <= 0);
116	atomic_inc(&wf->count);
117}
118
119/**
120 * intel_wakeref_get_if_active: Acquire the wakeref
121 * @wf: the wakeref
122 *
123 * Acquire a hold on the wakeref, but only if the wakeref is already
124 * active.
125 *
126 * Returns: true if the wakeref was acquired, false otherwise.
127 */
128static inline bool
129intel_wakeref_get_if_active(struct intel_wakeref *wf)
130{
131	return atomic_inc_not_zero(&wf->count);
132}
133
134enum {
135	INTEL_WAKEREF_PUT_ASYNC_BIT = 0,
136	__INTEL_WAKEREF_PUT_LAST_BIT__
137};
138
139static inline void
140intel_wakeref_might_get(struct intel_wakeref *wf)
141{
142	might_lock(&wf->mutex);
143}
144
145/**
146 * __intel_wakeref_put: Release the wakeref
147 * @wf: the wakeref
148 * @flags: control flags
149 *
150 * Release our hold on the wakeref. When there are no more users,
151 * the runtime pm wakeref will be released after the intel_wakeref_ops->put()
152 * callback is called underneath the wakeref mutex.
153 *
154 * Note that intel_wakeref_ops->put() is allowed to fail, in which case the
155 * runtime-pm wakeref is retained.
156 *
157 */
158static inline void
159__intel_wakeref_put(struct intel_wakeref *wf, unsigned long flags)
160#define INTEL_WAKEREF_PUT_ASYNC BIT(INTEL_WAKEREF_PUT_ASYNC_BIT)
161#define INTEL_WAKEREF_PUT_DELAY \
162	GENMASK(BITS_PER_LONG - 1, __INTEL_WAKEREF_PUT_LAST_BIT__)
163{
164	INTEL_WAKEREF_BUG_ON(atomic_read(&wf->count) <= 0);
165	if (unlikely(!atomic_add_unless(&wf->count, -1, 1)))
166		__intel_wakeref_put_last(wf, flags);
167}
168
169static inline void
170intel_wakeref_put(struct intel_wakeref *wf)
171{
172	might_sleep();
173	__intel_wakeref_put(wf, 0);
174}
175
176static inline void
177intel_wakeref_put_async(struct intel_wakeref *wf)
178{
179	__intel_wakeref_put(wf, INTEL_WAKEREF_PUT_ASYNC);
180}
181
182static inline void
183intel_wakeref_put_delay(struct intel_wakeref *wf, unsigned long delay)
184{
185	__intel_wakeref_put(wf,
186			    INTEL_WAKEREF_PUT_ASYNC |
187			    FIELD_PREP(INTEL_WAKEREF_PUT_DELAY, delay));
188}
189
190static inline void
191intel_wakeref_might_put(struct intel_wakeref *wf)
192{
193	might_lock(&wf->mutex);
194}
195
196/**
197 * intel_wakeref_lock: Lock the wakeref (mutex)
198 * @wf: the wakeref
199 *
200 * Locks the wakeref to prevent it being acquired or released. New users
201 * can still adjust the counter, but the wakeref itself (and callback)
202 * cannot be acquired or released.
203 */
204static inline void
205intel_wakeref_lock(struct intel_wakeref *wf)
206	__acquires(wf->mutex)
207{
208	mutex_lock(&wf->mutex);
209}
210
211/**
212 * intel_wakeref_unlock: Unlock the wakeref
213 * @wf: the wakeref
214 *
215 * Releases a previously acquired intel_wakeref_lock().
216 */
217static inline void
218intel_wakeref_unlock(struct intel_wakeref *wf)
219	__releases(wf->mutex)
220{
221	mutex_unlock(&wf->mutex);
222}
223
224/**
225 * intel_wakeref_unlock_wait: Wait until the active callback is complete
226 * @wf: the wakeref
227 *
228 * Waits for the active callback (under the @wf->mutex or another CPU) is
229 * complete.
230 */
231static inline void
232intel_wakeref_unlock_wait(struct intel_wakeref *wf)
233{
234	mutex_lock(&wf->mutex);
235	mutex_unlock(&wf->mutex);
236	flush_delayed_work(&wf->work);
237}
238
239/**
240 * intel_wakeref_is_active: Query whether the wakeref is currently held
241 * @wf: the wakeref
242 *
243 * Returns: true if the wakeref is currently held.
244 */
245static inline bool
246intel_wakeref_is_active(const struct intel_wakeref *wf)
247{
248	return READ_ONCE(wf->wakeref);
249}
250
251/**
252 * __intel_wakeref_defer_park: Defer the current park callback
253 * @wf: the wakeref
254 */
255static inline void
256__intel_wakeref_defer_park(struct intel_wakeref *wf)
257{
258	lockdep_assert_held(&wf->mutex);
259	INTEL_WAKEREF_BUG_ON(atomic_read(&wf->count));
260	atomic_set_release(&wf->count, 1);
261}
262
263/**
264 * intel_wakeref_wait_for_idle: Wait until the wakeref is idle
265 * @wf: the wakeref
266 *
267 * Wait for the earlier asynchronous release of the wakeref. Note
268 * this will wait for any third party as well, so make sure you only wait
269 * when you have control over the wakeref and trust no one else is acquiring
270 * it.
271 *
272 * Return: 0 on success, error code if killed.
273 */
274int intel_wakeref_wait_for_idle(struct intel_wakeref *wf);
275
276#define INTEL_WAKEREF_DEF ((intel_wakeref_t)(-1))
277
278static inline intel_wakeref_t intel_ref_tracker_alloc(struct ref_tracker_dir *dir)
279{
280	struct ref_tracker *user = NULL;
281
282	ref_tracker_alloc(dir, &user, GFP_NOWAIT);
283
284	return (intel_wakeref_t)user ?: INTEL_WAKEREF_DEF;
285}
286
287static inline void intel_ref_tracker_free(struct ref_tracker_dir *dir,
288					  intel_wakeref_t handle)
289{
290	struct ref_tracker *user;
291
292	user = (handle == INTEL_WAKEREF_DEF) ? NULL : (void *)handle;
293
294	ref_tracker_free(dir, &user);
295}
296
297void intel_ref_tracker_show(struct ref_tracker_dir *dir,
298			    struct drm_printer *p);
299
300#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_WAKEREF)
301
302static inline intel_wakeref_t intel_wakeref_track(struct intel_wakeref *wf)
303{
304	return intel_ref_tracker_alloc(&wf->debug);
305}
306
307static inline void intel_wakeref_untrack(struct intel_wakeref *wf,
308					 intel_wakeref_t handle)
309{
310	intel_ref_tracker_free(&wf->debug, handle);
311}
312
313#else
314
315static inline intel_wakeref_t intel_wakeref_track(struct intel_wakeref *wf)
316{
317	return -1;
318}
319
320static inline void intel_wakeref_untrack(struct intel_wakeref *wf,
321					 intel_wakeref_t handle)
322{
323}
324
325#endif
326
327struct intel_wakeref_auto {
328	struct drm_i915_private *i915;
329	struct timer_list timer;
330	intel_wakeref_t wakeref;
331	spinlock_t lock;
332	refcount_t count;
333};
334
335/**
336 * intel_wakeref_auto: Delay the runtime-pm autosuspend
337 * @wf: the wakeref
338 * @timeout: relative timeout in jiffies
339 *
340 * The runtime-pm core uses a suspend delay after the last wakeref
341 * is released before triggering runtime suspend of the device. That
342 * delay is configurable via sysfs with little regard to the device
343 * characteristics. Instead, we want to tune the autosuspend based on our
344 * HW knowledge. intel_wakeref_auto() delays the sleep by the supplied
345 * timeout.
346 *
347 * Pass @timeout = 0 to cancel a previous autosuspend by executing the
348 * suspend immediately.
349 */
350void intel_wakeref_auto(struct intel_wakeref_auto *wf, unsigned long timeout);
351
352void intel_wakeref_auto_init(struct intel_wakeref_auto *wf,
353			     struct drm_i915_private *i915);
354void intel_wakeref_auto_fini(struct intel_wakeref_auto *wf);
355
356#endif /* INTEL_WAKEREF_H */
357