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 } 187