drivers/gpu/drm/i915/intel_wakeref.c

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