drivers/base/power/runtime.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * drivers/base/power/runtime.c - Helper functions for device runtime PM
   4  *
   5  * Copyright (c) 2009 Rafael J. Wysocki <[email protected]>, Novell Inc.
   6  * Copyright (C) 2010 Alan Stern <[email protected]>
   7  */
   8 #include <linux/sched/mm.h>
   9 #include <linux/ktime.h>
  10 #include <linux/hrtimer.h>
  11 #include <linux/export.h>
  12 #include <linux/pm_runtime.h>
  13 #include <linux/pm_wakeirq.h>
  14 #include <trace/events/rpm.h>
  15
  16 #include "../base.h"
  17 #include "power.h"
  18
  19 typedef int (*pm_callback_t)(struct device *);
  20
  21 static pm_callback_t __rpm_get_callback(struct device *dev, size_t cb_offset)
  22 {
  23         pm_callback_t cb;
  24         const struct dev_pm_ops *ops;
  25
  26         if (dev->pm_domain)
  27                 ops = &dev->pm_domain->ops;
  28         else if (dev->type && dev->type->pm)
  29                 ops = dev->type->pm;
  30         else if (dev->class && dev->class->pm)
  31                 ops = dev->class->pm;
  32         else if (dev->bus && dev->bus->pm)
  33                 ops = dev->bus->pm;
  34         else
  35                 ops = NULL;
  36
  37         if (ops)
  38                 cb = *(pm_callback_t *)((void *)ops + cb_offset);
  39         else
  40                 cb = NULL;
  41
  42         if (!cb && dev->driver && dev->driver->pm)
  43                 cb = *(pm_callback_t *)((void *)dev->driver->pm + cb_offset);
  44
  45         return cb;
  46 }
  47
  48 #define RPM_GET_CALLBACK(dev, callback) \
  49                 __rpm_get_callback(dev, offsetof(struct dev_pm_ops, callback))
  50
  51 static int rpm_resume(struct device *dev, int rpmflags);
  52 static int rpm_suspend(struct device *dev, int rpmflags);
  53
  54 /**
  55  * update_pm_runtime_accounting - Update the time accounting of power states
  56  * @dev: Device to update the accounting for
  57  *
  58  * In order to be able to have time accounting of the various power states
  59  * (as used by programs such as PowerTOP to show the effectiveness of runtime
  60  * PM), we need to track the time spent in each state.
  61  * update_pm_runtime_accounting must be called each time before the
  62  * runtime_status field is updated, to account the time in the old state
  63  * correctly.
  64  */
  65 static void update_pm_runtime_accounting(struct device *dev)
  66 {
  67         u64 now, last, delta;
  68
  69         if (dev->power.disable_depth > 0)
  70                 return;
  71
  72         last = dev->power.accounting_timestamp;
  73
  74         now = ktime_get_mono_fast_ns();
  75         dev->power.accounting_timestamp = now;
  76
  77         /*
  78          * Because ktime_get_mono_fast_ns() is not monotonic during
  79          * timekeeping updates, ensure that 'now' is after the last saved
  80          * timesptamp.
  81          */
  82         if (now < last)
  83                 return;
  84
  85         delta = now - last;
  86
  87         if (dev->power.runtime_status == RPM_SUSPENDED)
  88                 dev->power.suspended_time += delta;
  89         else
  90                 dev->power.active_time += delta;
  91 }
  92
  93 static void __update_runtime_status(struct device *dev, enum rpm_status status)
  94 {
  95         update_pm_runtime_accounting(dev);
  96         dev->power.runtime_status = status;
  97 }
  98
  99 static u64 rpm_get_accounted_time(struct device *dev, bool suspended)
 100 {
 101         u64 time;
 102         unsigned long flags;
 103
 104         spin_lock_irqsave(&dev->power.lock, flags);
 105
 106         update_pm_runtime_accounting(dev);
 107         time = suspended ? dev->power.suspended_time : dev->power.active_time;
 108
 109         spin_unlock_irqrestore(&dev->power.lock, flags);
 110
 111         return time;
 112 }
 113
 114 u64 pm_runtime_active_time(struct device *dev)
 115 {
 116         return rpm_get_accounted_time(dev, false);
 117 }
 118
 119 u64 pm_runtime_suspended_time(struct device *dev)
 120 {
 121         return rpm_get_accounted_time(dev, true);
 122 }
 123 EXPORT_SYMBOL_GPL(pm_runtime_suspended_time);
 124
 125 /**
 126  * pm_runtime_deactivate_timer - Deactivate given device's suspend timer.
 127  * @dev: Device to handle.
 128  */
 129 static void pm_runtime_deactivate_timer(struct device *dev)
 130 {
 131         if (dev->power.timer_expires > 0) {
 132                 hrtimer_try_to_cancel(&dev->power.suspend_timer);
 133                 dev->power.timer_expires = 0;
 134         }
 135 }
 136
 137 /**
 138  * pm_runtime_cancel_pending - Deactivate suspend timer and cancel requests.
 139  * @dev: Device to handle.
 140  */
 141 static void pm_runtime_cancel_pending(struct device *dev)
 142 {
 143         pm_runtime_deactivate_timer(dev);
 144         /*
 145          * In case there's a request pending, make sure its work function will
 146          * return without doing anything.
 147          */
 148         dev->power.request = RPM_REQ_NONE;
 149 }
 150
 151 /*
 152  * pm_runtime_autosuspend_expiration - Get a device's autosuspend-delay expiration time.
 153  * @dev: Device to handle.
 154  *
 155  * Compute the autosuspend-delay expiration time based on the device's
 156  * power.last_busy time.  If the delay has already expired or is disabled
 157  * (negative) or the power.use_autosuspend flag isn't set, return 0.
 158  * Otherwise return the expiration time in nanoseconds (adjusted to be nonzero).
 159  *
 160  * This function may be called either with or without dev->power.lock held.
 161  * Either way it can be racy, since power.last_busy may be updated at any time.
 162  */
 163 u64 pm_runtime_autosuspend_expiration(struct device *dev)
 164 {
 165         int autosuspend_delay;
 166         u64 expires;
 167
 168         if (!dev->power.use_autosuspend)
 169                 return 0;
 170
 171         autosuspend_delay = READ_ONCE(dev->power.autosuspend_delay);
 172         if (autosuspend_delay < 0)
 173                 return 0;
 174
 175         expires  = READ_ONCE(dev->power.last_busy);
 176         expires += (u64)autosuspend_delay * NSEC_PER_MSEC;
 177         if (expires > ktime_get_mono_fast_ns())
 178                 return expires; /* Expires in the future */
 179
 180         return 0;
 181 }
 182 EXPORT_SYMBOL_GPL(pm_runtime_autosuspend_expiration);
 183
 184 static int dev_memalloc_noio(struct device *dev, void *data)
 185 {
 186         return dev->power.memalloc_noio;
 187 }
 188
 189 /*
 190  * pm_runtime_set_memalloc_noio - Set a device's memalloc_noio flag.
 191  * @dev: Device to handle.
 192  * @enable: True for setting the flag and False for clearing the flag.
 193  *
 194  * Set the flag for all devices in the path from the device to the
 195  * root device in the device tree if @enable is true, otherwise clear
 196  * the flag for devices in the path whose siblings don't set the flag.
 197  *
 198  * The function should only be called by block device, or network
 199  * device driver for solving the deadlock problem during runtime
 200  * resume/suspend:
 201  *
 202  *     If memory allocation with GFP_KERNEL is called inside runtime
 203  *     resume/suspend callback of any one of its ancestors(or the
 204  *     block device itself), the deadlock may be triggered inside the
 205  *     memory allocation since it might not complete until the block
 206  *     device becomes active and the involed page I/O finishes. The
 207  *     situation is pointed out first by Alan Stern. Network device
 208  *     are involved in iSCSI kind of situation.
 209  *
 210  * The lock of dev_hotplug_mutex is held in the function for handling
 211  * hotplug race because pm_runtime_set_memalloc_noio() may be called
 212  * in async probe().
 213  *
 214  * The function should be called between device_add() and device_del()
 215  * on the affected device(block/network device).
 216  */
 217 void pm_runtime_set_memalloc_noio(struct device *dev, bool enable)
 218 {
 219         static DEFINE_MUTEX(dev_hotplug_mutex);
 220
 221         mutex_lock(&dev_hotplug_mutex);
 222         for (;;) {
 223                 bool enabled;
 224
 225                 /* hold power lock since bitfield is not SMP-safe. */
 226                 spin_lock_irq(&dev->power.lock);
 227                 enabled = dev->power.memalloc_noio;
 228                 dev->power.memalloc_noio = enable;
 229                 spin_unlock_irq(&dev->power.lock);
 230
 231                 /*
 232                  * not need to enable ancestors any more if the device
 233                  * has been enabled.
 234                  */
 235                 if (enabled && enable)
 236                         break;
 237
 238                 dev = dev->parent;
 239
 240                 /*
 241                  * clear flag of the parent device only if all the
 242                  * children don't set the flag because ancestor's
 243                  * flag was set by any one of the descendants.
 244                  */
 245                 if (!dev || (!enable &&
 246                              device_for_each_child(dev, NULL,
 247                                                    dev_memalloc_noio)))
 248                         break;
 249         }
 250         mutex_unlock(&dev_hotplug_mutex);
 251 }
 252 EXPORT_SYMBOL_GPL(pm_runtime_set_memalloc_noio);
 253
 254 /**
 255  * rpm_check_suspend_allowed - Test whether a device may be suspended.
 256  * @dev: Device to test.
 257  */
 258 static int rpm_check_suspend_allowed(struct device *dev)
 259 {
 260         int retval = 0;
 261
 262         if (dev->power.runtime_error)
 263                 retval = -EINVAL;
 264         else if (dev->power.disable_depth > 0)
 265                 retval = -EACCES;
 266         else if (atomic_read(&dev->power.usage_count) > 0)
 267                 retval = -EAGAIN;
 268         else if (!dev->power.ignore_children &&
 269                         atomic_read(&dev->power.child_count))
 270                 retval = -EBUSY;
 271
 272         /* Pending resume requests take precedence over suspends. */
 273         else if ((dev->power.deferred_resume
 274                         && dev->power.runtime_status == RPM_SUSPENDING)
 275             || (dev->power.request_pending
 276                         && dev->power.request == RPM_REQ_RESUME))
 277                 retval = -EAGAIN;
 278         else if (__dev_pm_qos_resume_latency(dev) == 0)
 279                 retval = -EPERM;
 280         else if (dev->power.runtime_status == RPM_SUSPENDED)
 281                 retval = 1;
 282
 283         return retval;
 284 }
 285
 286 static int rpm_get_suppliers(struct device *dev)
 287 {
 288         struct device_link *link;
 289
 290         list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
 291                                 device_links_read_lock_held()) {
 292                 int retval;
 293
 294                 if (!(link->flags & DL_FLAG_PM_RUNTIME) ||
 295                     READ_ONCE(link->status) == DL_STATE_SUPPLIER_UNBIND)
 296                         continue;
 297
 298                 retval = pm_runtime_get_sync(link->supplier);
 299                 /* Ignore suppliers with disabled runtime PM. */
 300                 if (retval < 0 && retval != -EACCES) {
 301                         pm_runtime_put_noidle(link->supplier);
 302                         return retval;
 303                 }
 304                 refcount_inc(&link->rpm_active);
 305         }
 306         return 0;
 307 }
 308
 309 static void rpm_put_suppliers(struct device *dev)
 310 {
 311         struct device_link *link;
 312
 313         list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
 314                                 device_links_read_lock_held()) {
 315                 if (READ_ONCE(link->status) == DL_STATE_SUPPLIER_UNBIND)
 316                         continue;
 317
 318                 while (refcount_dec_not_one(&link->rpm_active))
 319                         pm_runtime_put(link->supplier);
 320         }
 321 }
 322
 323 /**
 324  * __rpm_callback - Run a given runtime PM callback for a given device.
 325  * @cb: Runtime PM callback to run.
 326  * @dev: Device to run the callback for.
 327  */
 328 static int __rpm_callback(int (*cb)(struct device *), struct device *dev)
 329         __releases(&dev->power.lock) __acquires(&dev->power.lock)
 330 {
 331         int retval, idx;
 332         bool use_links = dev->power.links_count > 0;
 333
 334         if (dev->power.irq_safe) {
 335                 spin_unlock(&dev->power.lock);
 336         } else {
 337                 spin_unlock_irq(&dev->power.lock);
 338
 339                 /*
 340                  * Resume suppliers if necessary.
 341                  *
 342                  * The device's runtime PM status cannot change until this
 343                  * routine returns, so it is safe to read the status outside of
 344                  * the lock.
 345                  */
 346                 if (use_links && dev->power.runtime_status == RPM_RESUMING) {
 347                         idx = device_links_read_lock();
 348
 349                         retval = rpm_get_suppliers(dev);
 350                         if (retval)
 351                                 goto fail;
 352
 353                         device_links_read_unlock(idx);
 354                 }
 355         }
 356
 357         retval = cb(dev);
 358
 359         if (dev->power.irq_safe) {
 360                 spin_lock(&dev->power.lock);
 361         } else {
 362                 /*
 363                  * If the device is suspending and the callback has returned
 364                  * success, drop the usage counters of the suppliers that have
 365                  * been reference counted on its resume.
 366                  *
 367                  * Do that if resume fails too.
 368                  */
 369                 if (use_links
 370                     && ((dev->power.runtime_status == RPM_SUSPENDING && !retval)
 371                     || (dev->power.runtime_status == RPM_RESUMING && retval))) {
 372                         idx = device_links_read_lock();
 373
 374  fail:
 375                         rpm_put_suppliers(dev);
 376
 377                         device_links_read_unlock(idx);
 378                 }
 379
 380                 spin_lock_irq(&dev->power.lock);
 381         }
 382
 383         return retval;
 384 }
 385
 386 /**
 387  * rpm_idle - Notify device bus type if the device can be suspended.
 388  * @dev: Device to notify the bus type about.
 389  * @rpmflags: Flag bits.
 390  *
 391  * Check if the device's runtime PM status allows it to be suspended.  If
 392  * another idle notification has been started earlier, return immediately.  If
 393  * the RPM_ASYNC flag is set then queue an idle-notification request; otherwise
 394  * run the ->runtime_idle() callback directly. If the ->runtime_idle callback
 395  * doesn't exist or if it returns 0, call rpm_suspend with the RPM_AUTO flag.
 396  *
 397  * This function must be called under dev->power.lock with interrupts disabled.
 398  */
 399 static int rpm_idle(struct device *dev, int rpmflags)
 400 {
 401         int (*callback)(struct device *);
 402         int retval;
 403
 404         trace_rpm_idle_rcuidle(dev, rpmflags);
 405         retval = rpm_check_suspend_allowed(dev);
 406         if (retval < 0)
 407                 ;       /* Conditions are wrong. */
 408
 409         /* Idle notifications are allowed only in the RPM_ACTIVE state. */
 410         else if (dev->power.runtime_status != RPM_ACTIVE)
 411                 retval = -EAGAIN;
 412
 413         /*
 414          * Any pending request other than an idle notification takes
 415          * precedence over us, except that the timer may be running.
 416          */
 417         else if (dev->power.request_pending &&
 418             dev->power.request > RPM_REQ_IDLE)
 419                 retval = -EAGAIN;
 420
 421         /* Act as though RPM_NOWAIT is always set. */
 422         else if (dev->power.idle_notification)
 423                 retval = -EINPROGRESS;
 424         if (retval)
 425                 goto out;
 426
 427         /* Pending requests need to be canceled. */
 428         dev->power.request = RPM_REQ_NONE;
 429
 430         if (dev->power.no_callbacks)
 431                 goto out;
 432
 433         /* Carry out an asynchronous or a synchronous idle notification. */
 434         if (rpmflags & RPM_ASYNC) {
 435                 dev->power.request = RPM_REQ_IDLE;
 436                 if (!dev->power.request_pending) {
 437                         dev->power.request_pending = true;
 438                         queue_work(pm_wq, &dev->power.work);
 439                 }
 440                 trace_rpm_return_int_rcuidle(dev, _THIS_IP_, 0);
 441                 return 0;
 442         }
 443
 444         dev->power.idle_notification = true;
 445
 446         callback = RPM_GET_CALLBACK(dev, runtime_idle);
 447
 448         if (callback)
 449                 retval = __rpm_callback(callback, dev);
 450
 451         dev->power.idle_notification = false;
 452         wake_up_all(&dev->power.wait_queue);
 453
 454  out:
 455         trace_rpm_return_int_rcuidle(dev, _THIS_IP_, retval);
 456         return retval ? retval : rpm_suspend(dev, rpmflags | RPM_AUTO);
 457 }
 458
 459 /**
 460  * rpm_callback - Run a given runtime PM callback for a given device.
 461  * @cb: Runtime PM callback to run.
 462  * @dev: Device to run the callback for.
 463  */
 464 static int rpm_callback(int (*cb)(struct device *), struct device *dev)
 465 {
 466         int retval;
 467
 468         if (!cb)
 469                 return -ENOSYS;
 470
 471         if (dev->power.memalloc_noio) {
 472                 unsigned int noio_flag;
 473
 474                 /*
 475                  * Deadlock might be caused if memory allocation with
 476                  * GFP_KERNEL happens inside runtime_suspend and
 477                  * runtime_resume callbacks of one block device's
 478                  * ancestor or the block device itself. Network
 479                  * device might be thought as part of iSCSI block
 480                  * device, so network device and its ancestor should
 481                  * be marked as memalloc_noio too.
 482                  */
 483                 noio_flag = memalloc_noio_save();
 484                 retval = __rpm_callback(cb, dev);
 485                 memalloc_noio_restore(noio_flag);
 486         } else {
 487                 retval = __rpm_callback(cb, dev);
 488         }
 489
 490         dev->power.runtime_error = retval;
 491         return retval != -EACCES ? retval : -EIO;
 492 }
 493
 494 /**
 495  * rpm_suspend - Carry out runtime suspend of given device.
 496  * @dev: Device to suspend.
 497  * @rpmflags: Flag bits.
 498  *
 499  * Check if the device's runtime PM status allows it to be suspended.
 500  * Cancel a pending idle notification, autosuspend or suspend. If
 501  * another suspend has been started earlier, either return immediately
 502  * or wait for it to finish, depending on the RPM_NOWAIT and RPM_ASYNC
 503  * flags. If the RPM_ASYNC flag is set then queue a suspend request;
 504  * otherwise run the ->runtime_suspend() callback directly. When
 505  * ->runtime_suspend succeeded, if a deferred resume was requested while
 506  * the callback was running then carry it out, otherwise send an idle
 507  * notification for its parent (if the suspend succeeded and both
 508  * ignore_children of parent->power and irq_safe of dev->power are not set).
 509  * If ->runtime_suspend failed with -EAGAIN or -EBUSY, and if the RPM_AUTO
 510  * flag is set and the next autosuspend-delay expiration time is in the
 511  * future, schedule another autosuspend attempt.
 512  *
 513  * This function must be called under dev->power.lock with interrupts disabled.
 514  */
 515 static int rpm_suspend(struct device *dev, int rpmflags)
 516         __releases(&dev->power.lock) __acquires(&dev->power.lock)
 517 {
 518         int (*callback)(struct device *);
 519         struct device *parent = NULL;
 520         int retval;
 521
 522         trace_rpm_suspend_rcuidle(dev, rpmflags);
 523
 524  repeat:
 525         retval = rpm_check_suspend_allowed(dev);
 526         if (retval < 0)
 527                 goto out;       /* Conditions are wrong. */
 528
 529         /* Synchronous suspends are not allowed in the RPM_RESUMING state. */
 530         if (dev->power.runtime_status == RPM_RESUMING && !(rpmflags & RPM_ASYNC))
 531                 retval = -EAGAIN;
 532         if (retval)
 533                 goto out;
 534
 535         /* If the autosuspend_delay time hasn't expired yet, reschedule. */
 536         if ((rpmflags & RPM_AUTO)
 537             && dev->power.runtime_status != RPM_SUSPENDING) {
 538                 u64 expires = pm_runtime_autosuspend_expiration(dev);
 539
 540                 if (expires != 0) {
 541                         /* Pending requests need to be canceled. */
 542                         dev->power.request = RPM_REQ_NONE;
 543
 544                         /*
 545                          * Optimization: If the timer is already running and is
 546                          * set to expire at or before the autosuspend delay,
 547                          * avoid the overhead of resetting it.  Just let it
 548                          * expire; pm_suspend_timer_fn() will take care of the
 549                          * rest.
 550                          */
 551                         if (!(dev->power.timer_expires &&
 552                                         dev->power.timer_expires <= expires)) {
 553                                 /*
 554                                  * We add a slack of 25% to gather wakeups
 555                                  * without sacrificing the granularity.
 556                                  */
 557                                 u64 slack = (u64)READ_ONCE(dev->power.autosuspend_delay) *
 558                                                     (NSEC_PER_MSEC >> 2);
 559
 560                                 dev->power.timer_expires = expires;
 561                                 hrtimer_start_range_ns(&dev->power.suspend_timer,
 562                                                 ns_to_ktime(expires),
 563                                                 slack,
 564                                                 HRTIMER_MODE_ABS);
 565                         }
 566                         dev->power.timer_autosuspends = 1;
 567                         goto out;
 568                 }
 569         }
 570
 571         /* Other scheduled or pending requests need to be canceled. */
 572         pm_runtime_cancel_pending(dev);
 573
 574         if (dev->power.runtime_status == RPM_SUSPENDING) {
 575                 DEFINE_WAIT(wait);
 576
 577                 if (rpmflags & (RPM_ASYNC | RPM_NOWAIT)) {
 578                         retval = -EINPROGRESS;
 579                         goto out;
 580                 }
 581
 582                 if (dev->power.irq_safe) {
 583                         spin_unlock(&dev->power.lock);
 584
 585                         cpu_relax();
 586
 587                         spin_lock(&dev->power.lock);
 588                         goto repeat;
 589                 }
 590
 591                 /* Wait for the other suspend running in parallel with us. */
 592                 for (;;) {
 593                         prepare_to_wait(&dev->power.wait_queue, &wait,
 594                                         TASK_UNINTERRUPTIBLE);
 595                         if (dev->power.runtime_status != RPM_SUSPENDING)
 596                                 break;
 597
 598                         spin_unlock_irq(&dev->power.lock);
 599
 600                         schedule();
 601
 602                         spin_lock_irq(&dev->power.lock);
 603                 }
 604                 finish_wait(&dev->power.wait_queue, &wait);
 605                 goto repeat;
 606         }
 607
 608         if (dev->power.no_callbacks)
 609                 goto no_callback;       /* Assume success. */
 610
 611         /* Carry out an asynchronous or a synchronous suspend. */
 612         if (rpmflags & RPM_ASYNC) {
 613                 dev->power.request = (rpmflags & RPM_AUTO) ?
 614                     RPM_REQ_AUTOSUSPEND : RPM_REQ_SUSPEND;
 615                 if (!dev->power.request_pending) {
 616                         dev->power.request_pending = true;
 617                         queue_work(pm_wq, &dev->power.work);
 618                 }
 619                 goto out;
 620         }
 621
 622         __update_runtime_status(dev, RPM_SUSPENDING);
 623
 624         callback = RPM_GET_CALLBACK(dev, runtime_suspend);
 625
 626         dev_pm_enable_wake_irq_check(dev, true);
 627         retval = rpm_callback(callback, dev);
 628         if (retval)
 629                 goto fail;
 630
 631  no_callback:
 632         __update_runtime_status(dev, RPM_SUSPENDED);
 633         pm_runtime_deactivate_timer(dev);
 634
 635         if (dev->parent) {
 636                 parent = dev->parent;
 637                 atomic_add_unless(&parent->power.child_count, -1, 0);
 638         }
 639         wake_up_all(&dev->power.wait_queue);
 640
 641         if (dev->power.deferred_resume) {
 642                 dev->power.deferred_resume = false;
 643                 rpm_resume(dev, 0);
 644                 retval = -EAGAIN;
 645                 goto out;
 646         }
 647
 648         /* Maybe the parent is now able to suspend. */
 649         if (parent && !parent->power.ignore_children && !dev->power.irq_safe) {
 650                 spin_unlock(&dev->power.lock);
 651
 652                 spin_lock(&parent->power.lock);
 653                 rpm_idle(parent, RPM_ASYNC);
 654                 spin_unlock(&parent->power.lock);
 655
 656                 spin_lock(&dev->power.lock);
 657         }
 658
 659  out:
 660         trace_rpm_return_int_rcuidle(dev, _THIS_IP_, retval);
 661
 662         return retval;
 663
 664  fail:
 665         dev_pm_disable_wake_irq_check(dev);
 666         __update_runtime_status(dev, RPM_ACTIVE);
 667         dev->power.deferred_resume = false;
 668         wake_up_all(&dev->power.wait_queue);
 669
 670         if (retval == -EAGAIN || retval == -EBUSY) {
 671                 dev->power.runtime_error = 0;
 672
 673                 /*
 674                  * If the callback routine failed an autosuspend, and
 675                  * if the last_busy time has been updated so that there
 676                  * is a new autosuspend expiration time, automatically
 677                  * reschedule another autosuspend.
 678                  */
 679                 if ((rpmflags & RPM_AUTO) &&
 680                     pm_runtime_autosuspend_expiration(dev) != 0)
 681                         goto repeat;
 682         } else {
 683                 pm_runtime_cancel_pending(dev);
 684         }
 685         goto out;
 686 }
 687
 688 /**
 689  * rpm_resume - Carry out runtime resume of given device.
 690  * @dev: Device to resume.
 691  * @rpmflags: Flag bits.
 692  *
 693  * Check if the device's runtime PM status allows it to be resumed.  Cancel
 694  * any scheduled or pending requests.  If another resume has been started
 695  * earlier, either return immediately or wait for it to finish, depending on the
 696  * RPM_NOWAIT and RPM_ASYNC flags.  Similarly, if there's a suspend running in
 697  * parallel with this function, either tell the other process to resume after
 698  * suspending (deferred_resume) or wait for it to finish.  If the RPM_ASYNC
 699  * flag is set then queue a resume request; otherwise run the
 700  * ->runtime_resume() callback directly.  Queue an idle notification for the
 701  * device if the resume succeeded.
 702  *
 703  * This function must be called under dev->power.lock with interrupts disabled.
 704  */
 705 static int rpm_resume(struct device *dev, int rpmflags)
 706         __releases(&dev->power.lock) __acquires(&dev->power.lock)
 707 {
 708         int (*callback)(struct device *);
 709         struct device *parent = NULL;
 710         int retval = 0;
 711
 712         trace_rpm_resume_rcuidle(dev, rpmflags);
 713
 714  repeat:
 715         if (dev->power.runtime_error)
 716                 retval = -EINVAL;
 717         else if (dev->power.disable_depth == 1 && dev->power.is_suspended
 718             && dev->power.runtime_status == RPM_ACTIVE)
 719                 retval = 1;
 720         else if (dev->power.disable_depth > 0)
 721                 retval = -EACCES;
 722         if (retval)
 723                 goto out;
 724
 725         /*
 726          * Other scheduled or pending requests need to be canceled.  Small
 727          * optimization: If an autosuspend timer is running, leave it running
 728          * rather than cancelling it now only to restart it again in the near
 729          * future.
 730          */
 731         dev->power.request = RPM_REQ_NONE;
 732         if (!dev->power.timer_autosuspends)
 733                 pm_runtime_deactivate_timer(dev);
 734
 735         if (dev->power.runtime_status == RPM_ACTIVE) {
 736                 retval = 1;
 737                 goto out;
 738         }
 739
 740         if (dev->power.runtime_status == RPM_RESUMING
 741             || dev->power.runtime_status == RPM_SUSPENDING) {
 742                 DEFINE_WAIT(wait);
 743
 744                 if (rpmflags & (RPM_ASYNC | RPM_NOWAIT)) {
 745                         if (dev->power.runtime_status == RPM_SUSPENDING)
 746                                 dev->power.deferred_resume = true;
 747                         else
 748                                 retval = -EINPROGRESS;
 749                         goto out;
 750                 }
 751
 752                 if (dev->power.irq_safe) {
 753                         spin_unlock(&dev->power.lock);
 754
 755                         cpu_relax();
 756
 757                         spin_lock(&dev->power.lock);
 758                         goto repeat;
 759                 }
 760
 761                 /* Wait for the operation carried out in parallel with us. */
 762                 for (;;) {
 763                         prepare_to_wait(&dev->power.wait_queue, &wait,
 764                                         TASK_UNINTERRUPTIBLE);
 765                         if (dev->power.runtime_status != RPM_RESUMING
 766                             && dev->power.runtime_status != RPM_SUSPENDING)
 767                                 break;
 768
 769                         spin_unlock_irq(&dev->power.lock);
 770
 771                         schedule();
 772
 773                         spin_lock_irq(&dev->power.lock);
 774                 }
 775                 finish_wait(&dev->power.wait_queue, &wait);
 776                 goto repeat;
 777         }
 778
 779         /*
 780          * See if we can skip waking up the parent.  This is safe only if
 781          * power.no_callbacks is set, because otherwise we don't know whether
 782          * the resume will actually succeed.
 783          */
 784         if (dev->power.no_callbacks && !parent && dev->parent) {
 785                 spin_lock_nested(&dev->parent->power.lock, SINGLE_DEPTH_NESTING);
 786                 if (dev->parent->power.disable_depth > 0
 787                     || dev->parent->power.ignore_children
 788                     || dev->parent->power.runtime_status == RPM_ACTIVE) {
 789                         atomic_inc(&dev->parent->power.child_count);
 790                         spin_unlock(&dev->parent->power.lock);
 791                         retval = 1;
 792                         goto no_callback;       /* Assume success. */
 793                 }
 794                 spin_unlock(&dev->parent->power.lock);
 795         }
 796
 797         /* Carry out an asynchronous or a synchronous resume. */
 798         if (rpmflags & RPM_ASYNC) {
 799                 dev->power.request = RPM_REQ_RESUME;
 800                 if (!dev->power.request_pending) {
 801                         dev->power.request_pending = true;
 802                         queue_work(pm_wq, &dev->power.work);
 803                 }
 804                 retval = 0;
 805                 goto out;
 806         }
 807
 808         if (!parent && dev->parent) {
 809                 /*
 810                  * Increment the parent's usage counter and resume it if
 811                  * necessary.  Not needed if dev is irq-safe; then the
 812                  * parent is permanently resumed.
 813                  */
 814                 parent = dev->parent;
 815                 if (dev->power.irq_safe)
 816                         goto skip_parent;
 817                 spin_unlock(&dev->power.lock);
 818
 819                 pm_runtime_get_noresume(parent);
 820
 821                 spin_lock(&parent->power.lock);
 822                 /*
 823                  * Resume the parent if it has runtime PM enabled and not been
 824                  * set to ignore its children.
 825                  */
 826                 if (!parent->power.disable_depth
 827                     && !parent->power.ignore_children) {
 828                         rpm_resume(parent, 0);
 829                         if (parent->power.runtime_status != RPM_ACTIVE)
 830                                 retval = -EBUSY;
 831                 }
 832                 spin_unlock(&parent->power.lock);
 833
 834                 spin_lock(&dev->power.lock);
 835                 if (retval)
 836                         goto out;
 837                 goto repeat;
 838         }
 839  skip_parent:
 840
 841         if (dev->power.no_callbacks)
 842                 goto no_callback;       /* Assume success. */
 843
 844         __update_runtime_status(dev, RPM_RESUMING);
 845
 846         callback = RPM_GET_CALLBACK(dev, runtime_resume);
 847
 848         dev_pm_disable_wake_irq_check(dev);
 849         retval = rpm_callback(callback, dev);
 850         if (retval) {
 851                 __update_runtime_status(dev, RPM_SUSPENDED);
 852                 pm_runtime_cancel_pending(dev);
 853                 dev_pm_enable_wake_irq_check(dev, false);
 854         } else {
 855  no_callback:
 856                 __update_runtime_status(dev, RPM_ACTIVE);
 857                 pm_runtime_mark_last_busy(dev);
 858                 if (parent)
 859                         atomic_inc(&parent->power.child_count);
 860         }
 861         wake_up_all(&dev->power.wait_queue);
 862
 863         if (retval >= 0)
 864                 rpm_idle(dev, RPM_ASYNC);
 865
 866  out:
 867         if (parent && !dev->power.irq_safe) {
 868                 spin_unlock_irq(&dev->power.lock);
 869
 870                 pm_runtime_put(parent);
 871
 872                 spin_lock_irq(&dev->power.lock);
 873         }
 874
 875         trace_rpm_return_int_rcuidle(dev, _THIS_IP_, retval);
 876
 877         return retval;
 878 }
 879
 880 /**
 881  * pm_runtime_work - Universal runtime PM work function.
 882  * @work: Work structure used for scheduling the execution of this function.
 883  *
 884  * Use @work to get the device object the work is to be done for, determine what
 885  * is to be done and execute the appropriate runtime PM function.
 886  */
 887 static void pm_runtime_work(struct work_struct *work)
 888 {
 889         struct device *dev = container_of(work, struct device, power.work);
 890         enum rpm_request req;
 891
 892         spin_lock_irq(&dev->power.lock);
 893
 894         if (!dev->power.request_pending)
 895                 goto out;
 896
 897         req = dev->power.request;
 898         dev->power.request = RPM_REQ_NONE;
 899         dev->power.request_pending = false;
 900
 901         switch (req) {
 902         case RPM_REQ_NONE:
 903                 break;
 904         case RPM_REQ_IDLE:
 905                 rpm_idle(dev, RPM_NOWAIT);
 906                 break;
 907         case RPM_REQ_SUSPEND:
 908                 rpm_suspend(dev, RPM_NOWAIT);
 909                 break;
 910         case RPM_REQ_AUTOSUSPEND:
 911                 rpm_suspend(dev, RPM_NOWAIT | RPM_AUTO);
 912                 break;
 913         case RPM_REQ_RESUME:
 914                 rpm_resume(dev, RPM_NOWAIT);
 915                 break;
 916         }
 917
 918  out:
 919         spin_unlock_irq(&dev->power.lock);
 920 }
 921
 922 /**
 923  * pm_suspend_timer_fn - Timer function for pm_schedule_suspend().
 924  * @data: Device pointer passed by pm_schedule_suspend().
 925  *
 926  * Check if the time is right and queue a suspend request.
 927  */
 928 static enum hrtimer_restart  pm_suspend_timer_fn(struct hrtimer *timer)
 929 {
 930         struct device *dev = container_of(timer, struct device, power.suspend_timer);
 931         unsigned long flags;
 932         u64 expires;
 933
 934         spin_lock_irqsave(&dev->power.lock, flags);
 935
 936         expires = dev->power.timer_expires;
 937         /*
 938          * If 'expires' is after the current time, we've been called
 939          * too early.
 940          */
 941         if (expires > 0 && expires < ktime_get_mono_fast_ns()) {
 942                 dev->power.timer_expires = 0;
 943                 rpm_suspend(dev, dev->power.timer_autosuspends ?
 944                     (RPM_ASYNC | RPM_AUTO) : RPM_ASYNC);
 945         }
 946
 947         spin_unlock_irqrestore(&dev->power.lock, flags);
 948
 949         return HRTIMER_NORESTART;
 950 }
 951
 952 /**
 953  * pm_schedule_suspend - Set up a timer to submit a suspend request in future.
 954  * @dev: Device to suspend.
 955  * @delay: Time to wait before submitting a suspend request, in milliseconds.
 956  */
 957 int pm_schedule_suspend(struct device *dev, unsigned int delay)
 958 {
 959         unsigned long flags;
 960         u64 expires;
 961         int retval;
 962
 963         spin_lock_irqsave(&dev->power.lock, flags);
 964
 965         if (!delay) {
 966                 retval = rpm_suspend(dev, RPM_ASYNC);
 967                 goto out;
 968         }
 969
 970         retval = rpm_check_suspend_allowed(dev);
 971         if (retval)
 972                 goto out;
 973
 974         /* Other scheduled or pending requests need to be canceled. */
 975         pm_runtime_cancel_pending(dev);
 976
 977         expires = ktime_get_mono_fast_ns() + (u64)delay * NSEC_PER_MSEC;
 978         dev->power.timer_expires = expires;
 979         dev->power.timer_autosuspends = 0;
 980         hrtimer_start(&dev->power.suspend_timer, expires, HRTIMER_MODE_ABS);
 981
 982  out:
 983         spin_unlock_irqrestore(&dev->power.lock, flags);
 984
 985         return retval;
 986 }
 987 EXPORT_SYMBOL_GPL(pm_schedule_suspend);
 988
 989 /**
 990  * __pm_runtime_idle - Entry point for runtime idle operations.
 991  * @dev: Device to send idle notification for.
 992  * @rpmflags: Flag bits.
 993  *
 994  * If the RPM_GET_PUT flag is set, decrement the device's usage count and
 995  * return immediately if it is larger than zero.  Then carry out an idle
 996  * notification, either synchronous or asynchronous.
 997  *
 998  * This routine may be called in atomic context if the RPM_ASYNC flag is set,
 999  * or if pm_runtime_irq_safe() has been called.
1000  */
1001 int __pm_runtime_idle(struct device *dev, int rpmflags)
1002 {
1003         unsigned long flags;
1004         int retval;
1005
1006         if (rpmflags & RPM_GET_PUT) {
1007                 if (!atomic_dec_and_test(&dev->power.usage_count)) {
1008                         trace_rpm_usage_rcuidle(dev, rpmflags);
1009                         return 0;
1010                 }
1011         }
1012
1013         might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);
1014
1015         spin_lock_irqsave(&dev->power.lock, flags);
1016         retval = rpm_idle(dev, rpmflags);
1017         spin_unlock_irqrestore(&dev->power.lock, flags);
1018
1019         return retval;
1020 }
1021 EXPORT_SYMBOL_GPL(__pm_runtime_idle);
1022
1023 /**
1024  * __pm_runtime_suspend - Entry point for runtime put/suspend operations.
1025  * @dev: Device to suspend.
1026  * @rpmflags: Flag bits.
1027  *
1028  * If the RPM_GET_PUT flag is set, decrement the device's usage count and
1029  * return immediately if it is larger than zero.  Then carry out a suspend,
1030  * either synchronous or asynchronous.
1031  *
1032  * This routine may be called in atomic context if the RPM_ASYNC flag is set,
1033  * or if pm_runtime_irq_safe() has been called.
1034  */
1035 int __pm_runtime_suspend(struct device *dev, int rpmflags)
1036 {
1037         unsigned long flags;
1038         int retval;
1039
1040         if (rpmflags & RPM_GET_PUT) {
1041                 if (!atomic_dec_and_test(&dev->power.usage_count)) {
1042                         trace_rpm_usage_rcuidle(dev, rpmflags);
1043                         return 0;
1044                 }
1045         }
1046
1047         might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);
1048
1049         spin_lock_irqsave(&dev->power.lock, flags);
1050         retval = rpm_suspend(dev, rpmflags);
1051         spin_unlock_irqrestore(&dev->power.lock, flags);
1052
1053         return retval;
1054 }
1055 EXPORT_SYMBOL_GPL(__pm_runtime_suspend);
1056
1057 /**
1058  * __pm_runtime_resume - Entry point for runtime resume operations.
1059  * @dev: Device to resume.
1060  * @rpmflags: Flag bits.
1061  *
1062  * If the RPM_GET_PUT flag is set, increment the device's usage count.  Then
1063  * carry out a resume, either synchronous or asynchronous.
1064  *
1065  * This routine may be called in atomic context if the RPM_ASYNC flag is set,
1066  * or if pm_runtime_irq_safe() has been called.
1067  */
1068 int __pm_runtime_resume(struct device *dev, int rpmflags)
1069 {
1070         unsigned long flags;
1071         int retval;
1072
1073         might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe &&
1074                         dev->power.runtime_status != RPM_ACTIVE);
1075
1076         if (rpmflags & RPM_GET_PUT)
1077                 atomic_inc(&dev->power.usage_count);
1078
1079         spin_lock_irqsave(&dev->power.lock, flags);
1080         retval = rpm_resume(dev, rpmflags);
1081         spin_unlock_irqrestore(&dev->power.lock, flags);
1082
1083         return retval;
1084 }
1085 EXPORT_SYMBOL_GPL(__pm_runtime_resume);
1086
1087 /**
1088  * pm_runtime_get_if_active - Conditionally bump up device usage counter.
1089  * @dev: Device to handle.
1090  * @ign_usage_count: Whether or not to look at the current usage counter value.
1091  *
1092  * Return -EINVAL if runtime PM is disabled for @dev.
1093  *
1094  * Otherwise, if the runtime PM status of @dev is %RPM_ACTIVE and either
1095  * @ign_usage_count is %true or the runtime PM usage counter of @dev is not
1096  * zero, increment the usage counter of @dev and return 1. Otherwise, return 0
1097  * without changing the usage counter.
1098  *
1099  * If @ign_usage_count is %true, this function can be used to prevent suspending
1100  * the device when its runtime PM status is %RPM_ACTIVE.
1101  *
1102  * If @ign_usage_count is %false, this function can be used to prevent
1103  * suspending the device when both its runtime PM status is %RPM_ACTIVE and its
1104  * runtime PM usage counter is not zero.
1105  *
1106  * The caller is resposible for decrementing the runtime PM usage counter of
1107  * @dev after this function has returned a positive value for it.
1108  */
1109 int pm_runtime_get_if_active(struct device *dev, bool ign_usage_count)
1110 {
1111         unsigned long flags;
1112         int retval;
1113
1114         spin_lock_irqsave(&dev->power.lock, flags);
1115         if (dev->power.disable_depth > 0) {
1116                 retval = -EINVAL;
1117         } else if (dev->power.runtime_status != RPM_ACTIVE) {
1118                 retval = 0;
1119         } else if (ign_usage_count) {
1120                 retval = 1;
1121                 atomic_inc(&dev->power.usage_count);
1122         } else {
1123                 retval = atomic_inc_not_zero(&dev->power.usage_count);
1124         }
1125         trace_rpm_usage_rcuidle(dev, 0);
1126         spin_unlock_irqrestore(&dev->power.lock, flags);
1127
1128         return retval;
1129 }
1130 EXPORT_SYMBOL_GPL(pm_runtime_get_if_active);
1131
1132 /**
1133  * __pm_runtime_set_status - Set runtime PM status of a device.
1134  * @dev: Device to handle.
1135  * @status: New runtime PM status of the device.
1136  *
1137  * If runtime PM of the device is disabled or its power.runtime_error field is
1138  * different from zero, the status may be changed either to RPM_ACTIVE, or to
1139  * RPM_SUSPENDED, as long as that reflects the actual state of the device.
1140  * However, if the device has a parent and the parent is not active, and the
1141  * parent's power.ignore_children flag is unset, the device's status cannot be
1142  * set to RPM_ACTIVE, so -EBUSY is returned in that case.
1143  *
1144  * If successful, __pm_runtime_set_status() clears the power.runtime_error field
1145  * and the device parent's counter of unsuspended children is modified to
1146  * reflect the new status.  If the new status is RPM_SUSPENDED, an idle
1147  * notification request for the parent is submitted.
1148  *
1149  * If @dev has any suppliers (as reflected by device links to them), and @status
1150  * is RPM_ACTIVE, they will be activated upfront and if the activation of one
1151  * of them fails, the status of @dev will be changed to RPM_SUSPENDED (instead
1152  * of the @status value) and the suppliers will be deacticated on exit.  The
1153  * error returned by the failing supplier activation will be returned in that
1154  * case.
1155  */
1156 int __pm_runtime_set_status(struct device *dev, unsigned int status)
1157 {
1158         struct device *parent = dev->parent;
1159         bool notify_parent = false;
1160         int error = 0;
1161
1162         if (status != RPM_ACTIVE && status != RPM_SUSPENDED)
1163                 return -EINVAL;
1164
1165         spin_lock_irq(&dev->power.lock);
1166
1167         /*
1168          * Prevent PM-runtime from being enabled for the device or return an
1169          * error if it is enabled already and working.
1170          */
1171         if (dev->power.runtime_error || dev->power.disable_depth)
1172                 dev->power.disable_depth++;
1173         else
1174                 error = -EAGAIN;
1175
1176         spin_unlock_irq(&dev->power.lock);
1177
1178         if (error)
1179                 return error;
1180
1181         /*
1182          * If the new status is RPM_ACTIVE, the suppliers can be activated
1183          * upfront regardless of the current status, because next time
1184          * rpm_put_suppliers() runs, the rpm_active refcounts of the links
1185          * involved will be dropped down to one anyway.
1186          */
1187         if (status == RPM_ACTIVE) {
1188                 int idx = device_links_read_lock();
1189
1190                 error = rpm_get_suppliers(dev);
1191                 if (error)
1192                         status = RPM_SUSPENDED;
1193
1194                 device_links_read_unlock(idx);
1195         }
1196
1197         spin_lock_irq(&dev->power.lock);
1198
1199         if (dev->power.runtime_status == status || !parent)
1200                 goto out_set;
1201
1202         if (status == RPM_SUSPENDED) {
1203                 atomic_add_unless(&parent->power.child_count, -1, 0);
1204                 notify_parent = !parent->power.ignore_children;
1205         } else {
1206                 spin_lock_nested(&parent->power.lock, SINGLE_DEPTH_NESTING);
1207
1208                 /*
1209                  * It is invalid to put an active child under a parent that is
1210                  * not active, has runtime PM enabled and the
1211                  * 'power.ignore_children' flag unset.
1212                  */
1213                 if (!parent->power.disable_depth
1214                     && !parent->power.ignore_children
1215                     && parent->power.runtime_status != RPM_ACTIVE) {
1216                         dev_err(dev, "runtime PM trying to activate child device %s but parent (%s) is not active\n",
1217                                 dev_name(dev),
1218                                 dev_name(parent));
1219                         error = -EBUSY;
1220                 } else if (dev->power.runtime_status == RPM_SUSPENDED) {
1221                         atomic_inc(&parent->power.child_count);
1222                 }
1223
1224                 spin_unlock(&parent->power.lock);
1225
1226                 if (error) {
1227                         status = RPM_SUSPENDED;
1228                         goto out;
1229                 }
1230         }
1231
1232  out_set:
1233         __update_runtime_status(dev, status);
1234         if (!error)
1235                 dev->power.runtime_error = 0;
1236
1237  out:
1238         spin_unlock_irq(&dev->power.lock);
1239
1240         if (notify_parent)
1241                 pm_request_idle(parent);
1242
1243         if (status == RPM_SUSPENDED) {
1244                 int idx = device_links_read_lock();
1245
1246                 rpm_put_suppliers(dev);
1247
1248                 device_links_read_unlock(idx);
1249         }
1250
1251         pm_runtime_enable(dev);
1252
1253         return error;
1254 }
1255 EXPORT_SYMBOL_GPL(__pm_runtime_set_status);
1256
1257 /**
1258  * __pm_runtime_barrier - Cancel pending requests and wait for completions.
1259  * @dev: Device to handle.
1260  *
1261  * Flush all pending requests for the device from pm_wq and wait for all
1262  * runtime PM operations involving the device in progress to complete.
1263  *
1264  * Should be called under dev->power.lock with interrupts disabled.
1265  */
1266 static void __pm_runtime_barrier(struct device *dev)
1267 {
1268         pm_runtime_deactivate_timer(dev);
1269
1270         if (dev->power.request_pending) {
1271                 dev->power.request = RPM_REQ_NONE;
1272                 spin_unlock_irq(&dev->power.lock);
1273
1274                 cancel_work_sync(&dev->power.work);
1275
1276                 spin_lock_irq(&dev->power.lock);
1277                 dev->power.request_pending = false;
1278         }
1279
1280         if (dev->power.runtime_status == RPM_SUSPENDING
1281             || dev->power.runtime_status == RPM_RESUMING
1282             || dev->power.idle_notification) {
1283                 DEFINE_WAIT(wait);
1284
1285                 /* Suspend, wake-up or idle notification in progress. */
1286                 for (;;) {
1287                         prepare_to_wait(&dev->power.wait_queue, &wait,
1288                                         TASK_UNINTERRUPTIBLE);
1289                         if (dev->power.runtime_status != RPM_SUSPENDING
1290                             && dev->power.runtime_status != RPM_RESUMING
1291                             && !dev->power.idle_notification)
1292                                 break;
1293                         spin_unlock_irq(&dev->power.lock);
1294
1295                         schedule();
1296
1297                         spin_lock_irq(&dev->power.lock);
1298                 }
1299                 finish_wait(&dev->power.wait_queue, &wait);
1300         }
1301 }
1302
1303 /**
1304  * pm_runtime_barrier - Flush pending requests and wait for completions.
1305  * @dev: Device to handle.
1306  *
1307  * Prevent the device from being suspended by incrementing its usage counter and
1308  * if there's a pending resume request for the device, wake the device up.
1309  * Next, make sure that all pending requests for the device have been flushed
1310  * from pm_wq and wait for all runtime PM operations involving the device in
1311  * progress to complete.
1312  *
1313  * Return value:
1314  * 1, if there was a resume request pending and the device had to be woken up,
1315  * 0, otherwise
1316  */
1317 int pm_runtime_barrier(struct device *dev)
1318 {
1319         int retval = 0;
1320
1321         pm_runtime_get_noresume(dev);
1322         spin_lock_irq(&dev->power.lock);
1323
1324         if (dev->power.request_pending
1325             && dev->power.request == RPM_REQ_RESUME) {
1326                 rpm_resume(dev, 0);
1327                 retval = 1;
1328         }
1329
1330         __pm_runtime_barrier(dev);
1331
1332         spin_unlock_irq(&dev->power.lock);
1333         pm_runtime_put_noidle(dev);
1334
1335         return retval;
1336 }
1337 EXPORT_SYMBOL_GPL(pm_runtime_barrier);
1338
1339 /**
1340  * __pm_runtime_disable - Disable runtime PM of a device.
1341  * @dev: Device to handle.
1342  * @check_resume: If set, check if there's a resume request for the device.
1343  *
1344  * Increment power.disable_depth for the device and if it was zero previously,
1345  * cancel all pending runtime PM requests for the device and wait for all
1346  * operations in progress to complete.  The device can be either active or
1347  * suspended after its runtime PM has been disabled.
1348  *
1349  * If @check_resume is set and there's a resume request pending when
1350  * __pm_runtime_disable() is called and power.disable_depth is zero, the
1351  * function will wake up the device before disabling its runtime PM.
1352  */
1353 void __pm_runtime_disable(struct device *dev, bool check_resume)
1354 {
1355         spin_lock_irq(&dev->power.lock);
1356
1357         if (dev->power.disable_depth > 0) {
1358                 dev->power.disable_depth++;
1359                 goto out;
1360         }
1361
1362         /*
1363          * Wake up the device if there's a resume request pending, because that
1364          * means there probably is some I/O to process and disabling runtime PM
1365          * shouldn't prevent the device from processing the I/O.
1366          */
1367         if (check_resume && dev->power.request_pending
1368             && dev->power.request == RPM_REQ_RESUME) {
1369                 /*
1370                  * Prevent suspends and idle notifications from being carried
1371                  * out after we have woken up the device.
1372                  */
1373                 pm_runtime_get_noresume(dev);
1374
1375                 rpm_resume(dev, 0);
1376
1377                 pm_runtime_put_noidle(dev);
1378         }
1379
1380         /* Update time accounting before disabling PM-runtime. */
1381         update_pm_runtime_accounting(dev);
1382
1383         if (!dev->power.disable_depth++)
1384                 __pm_runtime_barrier(dev);
1385
1386  out:
1387         spin_unlock_irq(&dev->power.lock);
1388 }
1389 EXPORT_SYMBOL_GPL(__pm_runtime_disable);
1390
1391 /**
1392  * pm_runtime_enable - Enable runtime PM of a device.
1393  * @dev: Device to handle.
1394  */
1395 void pm_runtime_enable(struct device *dev)
1396 {
1397         unsigned long flags;
1398
1399         spin_lock_irqsave(&dev->power.lock, flags);
1400
1401         if (dev->power.disable_depth > 0) {
1402                 dev->power.disable_depth--;
1403
1404                 /* About to enable runtime pm, set accounting_timestamp to now */
1405                 if (!dev->power.disable_depth)
1406                         dev->power.accounting_timestamp = ktime_get_mono_fast_ns();
1407         } else {
1408                 dev_warn(dev, "Unbalanced %s!\n", __func__);
1409         }
1410
1411         WARN(!dev->power.disable_depth &&
1412              dev->power.runtime_status == RPM_SUSPENDED &&
1413              !dev->power.ignore_children &&
1414              atomic_read(&dev->power.child_count) > 0,
1415              "Enabling runtime PM for inactive device (%s) with active children\n",
1416              dev_name(dev));
1417
1418         spin_unlock_irqrestore(&dev->power.lock, flags);
1419 }
1420 EXPORT_SYMBOL_GPL(pm_runtime_enable);
1421
1422 /**
1423  * pm_runtime_forbid - Block runtime PM of a device.
1424  * @dev: Device to handle.
1425  *
1426  * Increase the device's usage count and clear its power.runtime_auto flag,
1427  * so that it cannot be suspended at run time until pm_runtime_allow() is called
1428  * for it.
1429  */
1430 void pm_runtime_forbid(struct device *dev)
1431 {
1432         spin_lock_irq(&dev->power.lock);
1433         if (!dev->power.runtime_auto)
1434                 goto out;
1435
1436         dev->power.runtime_auto = false;
1437         atomic_inc(&dev->power.usage_count);
1438         rpm_resume(dev, 0);
1439
1440  out:
1441         spin_unlock_irq(&dev->power.lock);
1442 }
1443 EXPORT_SYMBOL_GPL(pm_runtime_forbid);
1444
1445 /**
1446  * pm_runtime_allow - Unblock runtime PM of a device.
1447  * @dev: Device to handle.
1448  *
1449  * Decrease the device's usage count and set its power.runtime_auto flag.
1450  */
1451 void pm_runtime_allow(struct device *dev)
1452 {
1453         spin_lock_irq(&dev->power.lock);
1454         if (dev->power.runtime_auto)
1455                 goto out;
1456
1457         dev->power.runtime_auto = true;
1458         if (atomic_dec_and_test(&dev->power.usage_count))
1459                 rpm_idle(dev, RPM_AUTO | RPM_ASYNC);
1460         else
1461                 trace_rpm_usage_rcuidle(dev, RPM_AUTO | RPM_ASYNC);
1462
1463  out:
1464         spin_unlock_irq(&dev->power.lock);
1465 }
1466 EXPORT_SYMBOL_GPL(pm_runtime_allow);
1467
1468 /**
1469  * pm_runtime_no_callbacks - Ignore runtime PM callbacks for a device.
1470  * @dev: Device to handle.
1471  *
1472  * Set the power.no_callbacks flag, which tells the PM core that this
1473  * device is power-managed through its parent and has no runtime PM
1474  * callbacks of its own.  The runtime sysfs attributes will be removed.
1475  */
1476 void pm_runtime_no_callbacks(struct device *dev)
1477 {
1478         spin_lock_irq(&dev->power.lock);
1479         dev->power.no_callbacks = 1;
1480         spin_unlock_irq(&dev->power.lock);
1481         if (device_is_registered(dev))
1482                 rpm_sysfs_remove(dev);
1483 }
1484 EXPORT_SYMBOL_GPL(pm_runtime_no_callbacks);
1485
1486 /**
1487  * pm_runtime_irq_safe - Leave interrupts disabled during callbacks.
1488  * @dev: Device to handle
1489  *
1490  * Set the power.irq_safe flag, which tells the PM core that the
1491  * ->runtime_suspend() and ->runtime_resume() callbacks for this device should
1492  * always be invoked with the spinlock held and interrupts disabled.  It also
1493  * causes the parent's usage counter to be permanently incremented, preventing
1494  * the parent from runtime suspending -- otherwise an irq-safe child might have
1495  * to wait for a non-irq-safe parent.
1496  */
1497 void pm_runtime_irq_safe(struct device *dev)
1498 {
1499         if (dev->parent)
1500                 pm_runtime_get_sync(dev->parent);
1501         spin_lock_irq(&dev->power.lock);
1502         dev->power.irq_safe = 1;
1503         spin_unlock_irq(&dev->power.lock);
1504 }
1505 EXPORT_SYMBOL_GPL(pm_runtime_irq_safe);
1506
1507 /**
1508  * update_autosuspend - Handle a change to a device's autosuspend settings.
1509  * @dev: Device to handle.
1510  * @old_delay: The former autosuspend_delay value.
1511  * @old_use: The former use_autosuspend value.
1512  *
1513  * Prevent runtime suspend if the new delay is negative and use_autosuspend is
1514  * set; otherwise allow it.  Send an idle notification if suspends are allowed.
1515  *
1516  * This function must be called under dev->power.lock with interrupts disabled.
1517  */
1518 static void update_autosuspend(struct device *dev, int old_delay, int old_use)
1519 {
1520         int delay = dev->power.autosuspend_delay;
1521
1522         /* Should runtime suspend be prevented now? */
1523         if (dev->power.use_autosuspend && delay < 0) {
1524
1525                 /* If it used to be allowed then prevent it. */
1526                 if (!old_use || old_delay >= 0) {
1527                         atomic_inc(&dev->power.usage_count);
1528                         rpm_resume(dev, 0);
1529                 } else {
1530                         trace_rpm_usage_rcuidle(dev, 0);
1531                 }
1532         }
1533
1534         /* Runtime suspend should be allowed now. */
1535         else {
1536
1537                 /* If it used to be prevented then allow it. */
1538                 if (old_use && old_delay < 0)
1539                         atomic_dec(&dev->power.usage_count);
1540
1541                 /* Maybe we can autosuspend now. */
1542                 rpm_idle(dev, RPM_AUTO);
1543         }
1544 }
1545
1546 /**
1547  * pm_runtime_set_autosuspend_delay - Set a device's autosuspend_delay value.
1548  * @dev: Device to handle.
1549  * @delay: Value of the new delay in milliseconds.
1550  *
1551  * Set the device's power.autosuspend_delay value.  If it changes to negative
1552  * and the power.use_autosuspend flag is set, prevent runtime suspends.  If it
1553  * changes the other way, allow runtime suspends.
1554  */
1555 void pm_runtime_set_autosuspend_delay(struct device *dev, int delay)
1556 {
1557         int old_delay, old_use;
1558
1559         spin_lock_irq(&dev->power.lock);
1560         old_delay = dev->power.autosuspend_delay;
1561         old_use = dev->power.use_autosuspend;
1562         dev->power.autosuspend_delay = delay;
1563         update_autosuspend(dev, old_delay, old_use);
1564         spin_unlock_irq(&dev->power.lock);
1565 }
1566 EXPORT_SYMBOL_GPL(pm_runtime_set_autosuspend_delay);
1567
1568 /**
1569  * __pm_runtime_use_autosuspend - Set a device's use_autosuspend flag.
1570  * @dev: Device to handle.
1571  * @use: New value for use_autosuspend.
1572  *
1573  * Set the device's power.use_autosuspend flag, and allow or prevent runtime
1574  * suspends as needed.
1575  */
1576 void __pm_runtime_use_autosuspend(struct device *dev, bool use)
1577 {
1578         int old_delay, old_use;
1579
1580         spin_lock_irq(&dev->power.lock);
1581         old_delay = dev->power.autosuspend_delay;
1582         old_use = dev->power.use_autosuspend;
1583         dev->power.use_autosuspend = use;
1584         update_autosuspend(dev, old_delay, old_use);
1585         spin_unlock_irq(&dev->power.lock);
1586 }
1587 EXPORT_SYMBOL_GPL(__pm_runtime_use_autosuspend);
1588
1589 /**
1590  * pm_runtime_init - Initialize runtime PM fields in given device object.
1591  * @dev: Device object to initialize.
1592  */
1593 void pm_runtime_init(struct device *dev)
1594 {
1595         dev->power.runtime_status = RPM_SUSPENDED;
1596         dev->power.idle_notification = false;
1597
1598         dev->power.disable_depth = 1;
1599         atomic_set(&dev->power.usage_count, 0);
1600
1601         dev->power.runtime_error = 0;
1602
1603         atomic_set(&dev->power.child_count, 0);
1604         pm_suspend_ignore_children(dev, false);
1605         dev->power.runtime_auto = true;
1606
1607         dev->power.request_pending = false;
1608         dev->power.request = RPM_REQ_NONE;
1609         dev->power.deferred_resume = false;
1610         INIT_WORK(&dev->power.work, pm_runtime_work);
1611
1612         dev->power.timer_expires = 0;
1613         hrtimer_init(&dev->power.suspend_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
1614         dev->power.suspend_timer.function = pm_suspend_timer_fn;
1615
1616         init_waitqueue_head(&dev->power.wait_queue);
1617 }
1618
1619 /**
1620  * pm_runtime_reinit - Re-initialize runtime PM fields in given device object.
1621  * @dev: Device object to re-initialize.
1622  */
1623 void pm_runtime_reinit(struct device *dev)
1624 {
1625         if (!pm_runtime_enabled(dev)) {
1626                 if (dev->power.runtime_status == RPM_ACTIVE)
1627                         pm_runtime_set_suspended(dev);
1628                 if (dev->power.irq_safe) {
1629                         spin_lock_irq(&dev->power.lock);
1630                         dev->power.irq_safe = 0;
1631                         spin_unlock_irq(&dev->power.lock);
1632                         if (dev->parent)
1633                                 pm_runtime_put(dev->parent);
1634                 }
1635         }
1636 }
1637
1638 /**
1639  * pm_runtime_remove - Prepare for removing a device from device hierarchy.
1640  * @dev: Device object being removed from device hierarchy.
1641  */
1642 void pm_runtime_remove(struct device *dev)
1643 {
1644         __pm_runtime_disable(dev, false);
1645         pm_runtime_reinit(dev);
1646 }
1647
1648 /**
1649  * pm_runtime_clean_up_links - Prepare links to consumers for driver removal.
1650  * @dev: Device whose driver is going to be removed.
1651  *
1652  * Check links from this device to any consumers and if any of them have active
1653  * runtime PM references to the device, drop the usage counter of the device
1654  * (as many times as needed).
1655  *
1656  * Links with the DL_FLAG_MANAGED flag unset are ignored.
1657  *
1658  * Since the device is guaranteed to be runtime-active at the point this is
1659  * called, nothing else needs to be done here.
1660  *
1661  * Moreover, this is called after device_links_busy() has returned 'false', so
1662  * the status of each link is guaranteed to be DL_STATE_SUPPLIER_UNBIND and
1663  * therefore rpm_active can't be manipulated concurrently.
1664  */
1665 void pm_runtime_clean_up_links(struct device *dev)
1666 {
1667         struct device_link *link;
1668         int idx;
1669
1670         idx = device_links_read_lock();
1671
1672         list_for_each_entry_rcu(link, &dev->links.consumers, s_node,
1673                                 device_links_read_lock_held()) {
1674                 if (!(link->flags & DL_FLAG_MANAGED))
1675                         continue;
1676
1677                 while (refcount_dec_not_one(&link->rpm_active))
1678                         pm_runtime_put_noidle(dev);
1679         }
1680
1681         device_links_read_unlock(idx);
1682 }
1683
1684 /**
1685  * pm_runtime_get_suppliers - Resume and reference-count supplier devices.
1686  * @dev: Consumer device.
1687  */
1688 void pm_runtime_get_suppliers(struct device *dev)
1689 {
1690         struct device_link *link;
1691         int idx;
1692
1693         idx = device_links_read_lock();
1694
1695         list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
1696                                 device_links_read_lock_held())
1697                 if (link->flags & DL_FLAG_PM_RUNTIME) {
1698                         link->supplier_preactivated = true;
1699                         refcount_inc(&link->rpm_active);
1700                         pm_runtime_get_sync(link->supplier);
1701                 }
1702
1703         device_links_read_unlock(idx);
1704 }
1705
1706 /**
1707  * pm_runtime_put_suppliers - Drop references to supplier devices.
1708  * @dev: Consumer device.
1709  */
1710 void pm_runtime_put_suppliers(struct device *dev)
1711 {
1712         struct device_link *link;
1713         int idx;
1714
1715         idx = device_links_read_lock();
1716
1717         list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
1718                                 device_links_read_lock_held())
1719                 if (link->supplier_preactivated) {
1720                         link->supplier_preactivated = false;
1721                         if (refcount_dec_not_one(&link->rpm_active))
1722                                 pm_runtime_put(link->supplier);
1723                 }
1724
1725         device_links_read_unlock(idx);
1726 }
1727
1728 void pm_runtime_new_link(struct device *dev)
1729 {
1730         spin_lock_irq(&dev->power.lock);
1731         dev->power.links_count++;
1732         spin_unlock_irq(&dev->power.lock);
1733 }
1734
1735 void pm_runtime_drop_link(struct device *dev)
1736 {
1737         spin_lock_irq(&dev->power.lock);
1738         WARN_ON(dev->power.links_count == 0);
1739         dev->power.links_count--;
1740         spin_unlock_irq(&dev->power.lock);
1741 }
1742
1743 static bool pm_runtime_need_not_resume(struct device *dev)
1744 {
1745         return atomic_read(&dev->power.usage_count) <= 1 &&
1746                 (atomic_read(&dev->power.child_count) == 0 ||
1747                  dev->power.ignore_children);
1748 }
1749
1750 /**
1751  * pm_runtime_force_suspend - Force a device into suspend state if needed.
1752  * @dev: Device to suspend.
1753  *
1754  * Disable runtime PM so we safely can check the device's runtime PM status and
1755  * if it is active, invoke its ->runtime_suspend callback to suspend it and
1756  * change its runtime PM status field to RPM_SUSPENDED.  Also, if the device's
1757  * usage and children counters don't indicate that the device was in use before
1758  * the system-wide transition under way, decrement its parent's children counter
1759  * (if there is a parent).  Keep runtime PM disabled to preserve the state
1760  * unless we encounter errors.
1761  *
1762  * Typically this function may be invoked from a system suspend callback to make
1763  * sure the device is put into low power state and it should only be used during
1764  * system-wide PM transitions to sleep states.  It assumes that the analogous
1765  * pm_runtime_force_resume() will be used to resume the device.
1766  */
1767 int pm_runtime_force_suspend(struct device *dev)
1768 {
1769         int (*callback)(struct device *);
1770         int ret;
1771
1772         pm_runtime_disable(dev);
1773         if (pm_runtime_status_suspended(dev))
1774                 return 0;
1775
1776         callback = RPM_GET_CALLBACK(dev, runtime_suspend);
1777
1778         ret = callback ? callback(dev) : 0;
1779         if (ret)
1780                 goto err;
1781
1782         /*
1783          * If the device can stay in suspend after the system-wide transition
1784          * to the working state that will follow, drop the children counter of
1785          * its parent, but set its status to RPM_SUSPENDED anyway in case this
1786          * function will be called again for it in the meantime.
1787          */
1788         if (pm_runtime_need_not_resume(dev))
1789                 pm_runtime_set_suspended(dev);
1790         else
1791                 __update_runtime_status(dev, RPM_SUSPENDED);
1792
1793         return 0;
1794
1795 err:
1796         pm_runtime_enable(dev);
1797         return ret;
1798 }
1799 EXPORT_SYMBOL_GPL(pm_runtime_force_suspend);
1800
1801 /**
1802  * pm_runtime_force_resume - Force a device into resume state if needed.
1803  * @dev: Device to resume.
1804  *
1805  * Prior invoking this function we expect the user to have brought the device
1806  * into low power state by a call to pm_runtime_force_suspend(). Here we reverse
1807  * those actions and bring the device into full power, if it is expected to be
1808  * used on system resume.  In the other case, we defer the resume to be managed
1809  * via runtime PM.
1810  *
1811  * Typically this function may be invoked from a system resume callback.
1812  */
1813 int pm_runtime_force_resume(struct device *dev)
1814 {
1815         int (*callback)(struct device *);
1816         int ret = 0;
1817
1818         if (!pm_runtime_status_suspended(dev) || pm_runtime_need_not_resume(dev))
1819                 goto out;
1820
1821         /*
1822          * The value of the parent's children counter is correct already, so
1823          * just update the status of the device.
1824          */
1825         __update_runtime_status(dev, RPM_ACTIVE);
1826
1827         callback = RPM_GET_CALLBACK(dev, runtime_resume);
1828
1829         ret = callback ? callback(dev) : 0;
1830         if (ret) {
1831                 pm_runtime_set_suspended(dev);
1832                 goto out;
1833         }
1834
1835         pm_runtime_mark_last_busy(dev);
1836 out:
1837         pm_runtime_enable(dev);
1838         return ret;
1839 }
1840 EXPORT_SYMBOL_GPL(pm_runtime_force_resume);