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