1/*
2 * SPDX-License-Identifier: MIT
3 *
4 * Copyright © 2019 Intel Corporation
5 */
6
7#include <linux/wait_bit.h>
8
9#include "intel_runtime_pm.h"
10#include "intel_wakeref.h"
11#include "i915_drv.h"
12
13int __intel_wakeref_get_first(struct intel_wakeref *wf)
14{
15 intel_wakeref_t wakeref;
16 int ret = 0;
17
18 wakeref = intel_runtime_pm_get(rpm: &wf->i915->runtime_pm);
19 /*
20 * Treat get/put as different subclasses, as we may need to run
21 * the put callback from under the shrinker and do not want to
22 * cross-contanimate that callback with any extra work performed
23 * upon acquiring the wakeref.
24 */
25 mutex_lock_nested(lock: &wf->mutex, SINGLE_DEPTH_NESTING);
26
27 if (!atomic_read(v: &wf->count)) {
28 INTEL_WAKEREF_BUG_ON(wf->wakeref);
29 wf->wakeref = wakeref;
30 wakeref = 0;
31
32 ret = wf->ops->get(wf);
33 if (ret) {
34 wakeref = xchg(&wf->wakeref, 0);
35 wake_up_var(var: &wf->wakeref);
36 goto unlock;
37 }
38
39 smp_mb__before_atomic(); /* release wf->count */
40 }
41
42 atomic_inc(v: &wf->count);
43 INTEL_WAKEREF_BUG_ON(atomic_read(&wf->count) <= 0);
44
45unlock:
46 mutex_unlock(lock: &wf->mutex);
47 if (unlikely(wakeref))
48 intel_runtime_pm_put(rpm: &wf->i915->runtime_pm, wref: wakeref);
49
50 return ret;
51}
52
53static void ____intel_wakeref_put_last(struct intel_wakeref *wf)
54{
55 intel_wakeref_t wakeref = 0;
56
57 INTEL_WAKEREF_BUG_ON(atomic_read(&wf->count) <= 0);
58 if (unlikely(!atomic_dec_and_test(&wf->count)))
59 goto unlock;
60
61 /* ops->put() must reschedule its own release on error/deferral */
62 if (likely(!wf->ops->put(wf))) {
63 INTEL_WAKEREF_BUG_ON(!wf->wakeref);
64 wakeref = xchg(&wf->wakeref, 0);
65 wake_up_var(var: &wf->wakeref);
66 }
67
68unlock:
69 mutex_unlock(lock: &wf->mutex);
70 if (wakeref)
71 intel_runtime_pm_put(rpm: &wf->i915->runtime_pm, wref: wakeref);
72}
73
74void __intel_wakeref_put_last(struct intel_wakeref *wf, unsigned long flags)
75{
76 INTEL_WAKEREF_BUG_ON(delayed_work_pending(&wf->work));
77
78 /* Assume we are not in process context and so cannot sleep. */
79 if (flags & INTEL_WAKEREF_PUT_ASYNC || !mutex_trylock(lock: &wf->mutex)) {
80 mod_delayed_work(wq: wf->i915->unordered_wq, dwork: &wf->work,
81 FIELD_GET(INTEL_WAKEREF_PUT_DELAY, flags));
82 return;
83 }
84
85 ____intel_wakeref_put_last(wf);
86}
87
88static void __intel_wakeref_put_work(struct work_struct *wrk)
89{
90 struct intel_wakeref *wf = container_of(wrk, typeof(*wf), work.work);
91
92 if (atomic_add_unless(v: &wf->count, a: -1, u: 1))
93 return;
94
95 mutex_lock(&wf->mutex);
96 ____intel_wakeref_put_last(wf);
97}
98
99void __intel_wakeref_init(struct intel_wakeref *wf,
100 struct drm_i915_private *i915,
101 const struct intel_wakeref_ops *ops,
102 struct intel_wakeref_lockclass *key)
103{
104 wf->i915 = i915;
105 wf->ops = ops;
106
107 __mutex_init(lock: &wf->mutex, name: "wakeref.mutex", key: &key->mutex);
108 atomic_set(v: &wf->count, i: 0);
109 wf->wakeref = 0;
110
111 INIT_DELAYED_WORK(&wf->work, __intel_wakeref_put_work);
112 lockdep_init_map(lock: &wf->work.work.lockdep_map,
113 name: "wakeref.work", key: &key->work, subclass: 0);
114}
115
116int intel_wakeref_wait_for_idle(struct intel_wakeref *wf)
117{
118 int err;
119
120 might_sleep();
121
122 err = wait_var_event_killable(&wf->wakeref,
123 !intel_wakeref_is_active(wf));
124 if (err)
125 return err;
126
127 intel_wakeref_unlock_wait(wf);
128 return 0;
129}
130
131static void wakeref_auto_timeout(struct timer_list *t)
132{
133 struct intel_wakeref_auto *wf = from_timer(wf, t, timer);
134 intel_wakeref_t wakeref;
135 unsigned long flags;
136
137 if (!refcount_dec_and_lock_irqsave(r: &wf->count, lock: &wf->lock, flags: &flags))
138 return;
139
140 wakeref = fetch_and_zero(&wf->wakeref);
141 spin_unlock_irqrestore(lock: &wf->lock, flags);
142
143 intel_runtime_pm_put(rpm: &wf->i915->runtime_pm, wref: wakeref);
144}
145
146void intel_wakeref_auto_init(struct intel_wakeref_auto *wf,
147 struct drm_i915_private *i915)
148{
149 spin_lock_init(&wf->lock);
150 timer_setup(&wf->timer, wakeref_auto_timeout, 0);
151 refcount_set(r: &wf->count, n: 0);
152 wf->wakeref = 0;
153 wf->i915 = i915;
154}
155
156void intel_wakeref_auto(struct intel_wakeref_auto *wf, unsigned long timeout)
157{
158 unsigned long flags;
159
160 if (!timeout) {
161 if (del_timer_sync(timer: &wf->timer))
162 wakeref_auto_timeout(t: &wf->timer);
163 return;
164 }
165
166 /* Our mission is that we only extend an already active wakeref */
167 assert_rpm_wakelock_held(rpm: &wf->i915->runtime_pm);
168
169 if (!refcount_inc_not_zero(r: &wf->count)) {
170 spin_lock_irqsave(&wf->lock, flags);
171 if (!refcount_inc_not_zero(r: &wf->count)) {
172 INTEL_WAKEREF_BUG_ON(wf->wakeref);
173 wf->wakeref =
174 intel_runtime_pm_get_if_in_use(rpm: &wf->i915->runtime_pm);
175 refcount_set(r: &wf->count, n: 1);
176 }
177 spin_unlock_irqrestore(lock: &wf->lock, flags);
178 }
179
180 /*
181 * If we extend a pending timer, we will only get a single timer
182 * callback and so need to cancel the local inc by running the
183 * elided callback to keep the wf->count balanced.
184 */
185 if (mod_timer(timer: &wf->timer, expires: jiffies + timeout))
186 wakeref_auto_timeout(t: &wf->timer);
187}
188
189void intel_wakeref_auto_fini(struct intel_wakeref_auto *wf)
190{
191 intel_wakeref_auto(wf, timeout: 0);
192 INTEL_WAKEREF_BUG_ON(wf->wakeref);
193}
194

source code of linux/drivers/gpu/drm/i915/intel_wakeref.c