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 intel_wakeref_lockclass *key) 99 { 100 wf->rpm = rpm; 101 wf->ops = ops; 102 103 #ifdef __linux__ 104 __mutex_init(&wf->mutex, "wakeref.mutex", &key->mutex); 105 #else 106 rw_init(&wf->mutex, "wakeref.mutex"); 107 #endif 108 atomic_set(&wf->count, 0); 109 wf->wakeref = 0; 110 111 INIT_WORK(&wf->work, __intel_wakeref_put_work); 112 lockdep_init_map(&wf->work.lockdep_map, "wakeref.work", &key->work, 0); 113 } 114 115 int intel_wakeref_wait_for_idle(struct intel_wakeref *wf) 116 { 117 int err; 118 119 might_sleep(); 120 121 err = wait_var_event_killable(&wf->wakeref, 122 !intel_wakeref_is_active(wf)); 123 if (err) 124 return err; 125 126 intel_wakeref_unlock_wait(wf); 127 return 0; 128 } 129 130 #ifdef __linux__ 131 static 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(&wf->count, &wf->lock, &flags)) 138 return; 139 140 wakeref = fetch_and_zero(&wf->wakeref); 141 spin_unlock_irqrestore(&wf->lock, flags); 142 143 intel_runtime_pm_put(wf->rpm, wakeref); 144 } 145 #else 146 static void wakeref_auto_timeout(void *arg) 147 { 148 struct intel_wakeref_auto *wf = arg; 149 intel_wakeref_t wakeref; 150 unsigned long flags; 151 152 if (!refcount_dec_and_lock_irqsave(&wf->count, &wf->lock, &flags)) 153 return; 154 155 wakeref = fetch_and_zero(&wf->wakeref); 156 spin_unlock_irqrestore(&wf->lock, flags); 157 158 intel_runtime_pm_put(wf->rpm, wakeref); 159 } 160 #endif 161 162 void intel_wakeref_auto_init(struct intel_wakeref_auto *wf, 163 struct intel_runtime_pm *rpm) 164 { 165 mtx_init(&wf->lock, IPL_TTY); 166 #ifdef __linux__ 167 timer_setup(&wf->timer, wakeref_auto_timeout, 0); 168 #else 169 timeout_set(&wf->timer, wakeref_auto_timeout, wf); 170 #endif 171 refcount_set(&wf->count, 0); 172 wf->wakeref = 0; 173 wf->rpm = rpm; 174 } 175 176 void intel_wakeref_auto(struct intel_wakeref_auto *wf, unsigned long timeout) 177 { 178 unsigned long flags; 179 180 if (!timeout) { 181 if (del_timer_sync(&wf->timer)) 182 wakeref_auto_timeout(&wf->timer); 183 return; 184 } 185 186 /* Our mission is that we only extend an already active wakeref */ 187 assert_rpm_wakelock_held(wf->rpm); 188 189 if (!refcount_inc_not_zero(&wf->count)) { 190 spin_lock_irqsave(&wf->lock, flags); 191 if (!refcount_inc_not_zero(&wf->count)) { 192 INTEL_WAKEREF_BUG_ON(wf->wakeref); 193 wf->wakeref = intel_runtime_pm_get_if_in_use(wf->rpm); 194 refcount_set(&wf->count, 1); 195 } 196 spin_unlock_irqrestore(&wf->lock, flags); 197 } 198 199 /* 200 * If we extend a pending timer, we will only get a single timer 201 * callback and so need to cancel the local inc by running the 202 * elided callback to keep the wf->count balanced. 203 */ 204 if (mod_timer(&wf->timer, jiffies + timeout)) 205 wakeref_auto_timeout(&wf->timer); 206 } 207 208 void intel_wakeref_auto_fini(struct intel_wakeref_auto *wf) 209 { 210 intel_wakeref_auto(wf, 0); 211 INTEL_WAKEREF_BUG_ON(wf->wakeref); 212 } 213