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 rwlock mutex;
39
40	intel_wakeref_t wakeref;
41
42#define drm_i915_private inteldrm_softc
43	struct drm_i915_private *i915;
44	const struct intel_wakeref_ops *ops;
45
46	struct delayed_work work;
47};
48
49struct intel_wakeref_lockclass {
50	struct lock_class_key mutex;
51	struct lock_class_key work;
52};
53
54void __intel_wakeref_init(struct intel_wakeref *wf,
55			  struct drm_i915_private *i915,
56			  const struct intel_wakeref_ops *ops,
57			  struct intel_wakeref_lockclass *key);
58#define intel_wakeref_init(wf, i915, ops) do {				\
59	static struct intel_wakeref_lockclass __key;			\
60									\
61	__intel_wakeref_init((wf), (i915), (ops), &__key);		\
62} while (0)
63
64int __intel_wakeref_get_first(struct intel_wakeref *wf);
65void __intel_wakeref_put_last(struct intel_wakeref *wf, unsigned long flags);
66
67/**
68 * intel_wakeref_get: Acquire the wakeref
69 * @wf: the wakeref
70 *
71 * Acquire a hold on the wakeref. The first user to do so, will acquire
72 * the runtime pm wakeref and then call the intel_wakeref_ops->get()
73 * underneath the wakeref mutex.
74 *
75 * Note that intel_wakeref_ops->get() is allowed to fail, in which case
76 * the runtime-pm wakeref will be released and the acquisition unwound,
77 * and an error reported.
78 *
79 * Returns: 0 if the wakeref was acquired successfully, or a negative error
80 * code otherwise.
81 */
82static inline int
83intel_wakeref_get(struct intel_wakeref *wf)
84{
85	might_sleep();
86	if (unlikely(!atomic_inc_not_zero(&wf->count)))
87		return __intel_wakeref_get_first(wf);
88
89	return 0;
90}
91
92/**
93 * __intel_wakeref_get: Acquire the wakeref, again
94 * @wf: the wakeref
95 *
96 * Increment the wakeref counter, only valid if it is already held by
97 * the caller.
98 *
99 * See intel_wakeref_get().
100 */
101static inline void
102__intel_wakeref_get(struct intel_wakeref *wf)
103{
104	INTEL_WAKEREF_BUG_ON(atomic_read(&wf->count) <= 0);
105	atomic_inc(&wf->count);
106}
107
108/**
109 * intel_wakeref_get_if_active: Acquire the wakeref
110 * @wf: the wakeref
111 *
112 * Acquire a hold on the wakeref, but only if the wakeref is already
113 * active.
114 *
115 * Returns: true if the wakeref was acquired, false otherwise.
116 */
117static inline bool
118intel_wakeref_get_if_active(struct intel_wakeref *wf)
119{
120	return atomic_inc_not_zero(&wf->count);
121}
122
123enum {
124	INTEL_WAKEREF_PUT_ASYNC_BIT = 0,
125	__INTEL_WAKEREF_PUT_LAST_BIT__
126};
127
128static inline void
129intel_wakeref_might_get(struct intel_wakeref *wf)
130{
131	might_lock(&wf->mutex);
132}
133
134/**
135 * __intel_wakeref_put: Release the wakeref
136 * @wf: the wakeref
137 * @flags: control flags
138 *
139 * Release our hold on the wakeref. When there are no more users,
140 * the runtime pm wakeref will be released after the intel_wakeref_ops->put()
141 * callback is called underneath the wakeref mutex.
142 *
143 * Note that intel_wakeref_ops->put() is allowed to fail, in which case the
144 * runtime-pm wakeref is retained.
145 *
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 drm_i915_private *i915;
267	struct timeout 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 drm_i915_private *i915);
292void intel_wakeref_auto_fini(struct intel_wakeref_auto *wf);
293
294#endif /* INTEL_WAKEREF_H */
295