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 <rjw@sisk.pl>, Novell Inc.
   6  * Copyright (C) 2010 Alan Stern <stern@rowland.harvard.edu>
   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
 527         if (retval < 0)
 528                 ;       /* Conditions are wrong. */
 529
 530         /* Synchronous suspends are not allowed in the RPM_RESUMING state. */
 531         else if (dev->power.runtime_status == RPM_RESUMING &&
 532             !(rpmflags & RPM_ASYNC))
 533                 retval = -EAGAIN;
 534         if (retval)
 535                 goto out;
 536
 537         /* If the autosuspend_delay time hasn't expired yet, reschedule. */
 538         if ((rpmflags & RPM_AUTO)
 539             && dev->power.runtime_status != RPM_SUSPENDING) {
 540                 u64 expires = pm_runtime_autosuspend_expiration(dev);
 541
 542                 if (expires != 0) {
 543                         /* Pending requests need to be canceled. */
 544                         dev->power.request = RPM_REQ_NONE;
 545
 546                         /*
 547                          * Optimization: If the timer is already running and is
 548                          * set to expire at or before the autosuspend delay,
 549                          * avoid the overhead of resetting it.  Just let it
 550                          * expire; pm_suspend_timer_fn() will take care of the
 551                          * rest.
 552                          */
 553                         if (!(dev->power.timer_expires &&
 554                                         dev->power.timer_expires <= expires)) {
 555                                 /*
 556                                  * We add a slack of 25% to gather wakeups
 557                                  * without sacrificing the granularity.
 558                                  */
 559                                 u64 slack = (u64)READ_ONCE(dev->power.autosuspend_delay) *
 560                                                     (NSEC_PER_MSEC >> 2);
 561
 562                                 dev->power.timer_expires = expires;
 563                                 hrtimer_start_range_ns(&dev->power.suspend_timer,
 564                                                 ns_to_ktime(expires),
 565                                                 slack,
 566                                                 HRTIMER_MODE_ABS);
 567                         }
 568                         dev->power.timer_autosuspends = 1;
 569                         goto out;
 570                 }
 571         }
 572
 573         /* Other scheduled or pending requests need to be canceled. */
 574         pm_runtime_cancel_pending(dev);
 575
 576         if (dev->power.runtime_status == RPM_SUSPENDING) {
 577                 DEFINE_WAIT(wait);
 578
 579                 if (rpmflags & (RPM_ASYNC | RPM_NOWAIT)) {
 580                         retval = -EINPROGRESS;
 581                         goto out;
 582                 }
 583
 584                 if (dev->power.irq_safe) {
 585                         spin_unlock(&dev->power.lock);
 586
 587                         cpu_relax();
 588
 589                         spin_lock(&dev->power.lock);
 590                         goto repeat;
 591                 }
 592
 593                 /* Wait for the other suspend running in parallel with us. */
 594                 for (;;) {
 595                         prepare_to_wait(&dev->power.wait_queue, &wait,
 596                                         TASK_UNINTERRUPTIBLE);
 597                         if (dev->power.runtime_status != RPM_SUSPENDING)
 598                                 break;
 599
 600                         spin_unlock_irq(&dev->power.lock);
 601
 602                         schedule();
 603
 604                         spin_lock_irq(&dev->power.lock);
 605                 }
 606                 finish_wait(&dev->power.wait_queue, &wait);
 607                 goto repeat;
 608         }
 609
 610         if (dev->power.no_callbacks)
 611                 goto no_callback;       /* Assume success. */
 612
 613         /* Carry out an asynchronous or a synchronous suspend. */
 614         if (rpmflags & RPM_ASYNC) {
 615                 dev->power.request = (rpmflags & RPM_AUTO) ?
 616                     RPM_REQ_AUTOSUSPEND : RPM_REQ_SUSPEND;
 617                 if (!dev->power.request_pending) {
 618                         dev->power.request_pending = true;
 619                         queue_work(pm_wq, &dev->power.work);
 620                 }
 621                 goto out;
 622         }
 623
 624         __update_runtime_status(dev, RPM_SUSPENDING);
 625
 626         callback = RPM_GET_CALLBACK(dev, runtime_suspend);
 627
 628         dev_pm_enable_wake_irq_check(dev, true);
 629         retval = rpm_callback(callback, dev);
 630         if (retval)
 631                 goto fail;
 632
 633  no_callback:
 634         __update_runtime_status(dev, RPM_SUSPENDED);
 635         pm_runtime_deactivate_timer(dev);
 636
 637         if (dev->parent) {
 638                 parent = dev->parent;
 639                 atomic_add_unless(&parent->power.child_count, -1, 0);
 640         }
 641         wake_up_all(&dev->power.wait_queue);
 642
 643         if (dev->power.deferred_resume) {
 644                 dev->power.deferred_resume = false;
 645                 rpm_resume(dev, 0);
 646                 retval = -EAGAIN;
 647                 goto out;
 648         }
 649
 650         /* Maybe the parent is now able to suspend. */
 651         if (parent && !parent->power.ignore_children && !dev->power.irq_safe) {
 652                 spin_unlock(&dev->power.lock);
 653
 654                 spin_lock(&parent->power.lock);
 655                 rpm_idle(parent, RPM_ASYNC);
 656                 spin_unlock(&parent->power.lock);
 657
 658                 spin_lock(&dev->power.lock);
 659         }
 660
 661  out:
 662         trace_rpm_return_int_rcuidle(dev, _THIS_IP_, retval);
 663
 664         return retval;
 665
 666  fail:
 667         dev_pm_disable_wake_irq_check(dev);
 668         __update_runtime_status(dev, RPM_ACTIVE);
 669         dev->power.deferred_resume = false;
 670         wake_up_all(&dev->power.wait_queue);
 671
 672         if (retval == -EAGAIN || retval == -EBUSY) {
 673                 dev->power.runtime_error = 0;
 674
 675                 /*
 676                  * If the callback routine failed an autosuspend, and
 677                  * if the last_busy time has been updated so that there
 678                  * is a new autosuspend expiration time, automatically
 679                  * reschedule another autosuspend.
 680                  */
 681                 if ((rpmflags & RPM_AUTO) &&
 682                     pm_runtime_autosuspend_expiration(dev) != 0)
 683                         goto repeat;
 684         } else {
 685                 pm_runtime_cancel_pending(dev);
 686         }
 687         goto out;
 688 }
 689
 690 /**
 691  * rpm_resume - Carry out runtime resume of given device.
 692  * @dev: Device to resume.
 693  * @rpmflags: Flag bits.
 694  *
 695  * Check if the device's runtime PM status allows it to be resumed.  Cancel
 696  * any scheduled or pending requests.  If another resume has been started
 697  * earlier, either return immediately or wait for it to finish, depending on the
 698  * RPM_NOWAIT and RPM_ASYNC flags.  Similarly, if there's a suspend running in
 699  * parallel with this function, either tell the other process to resume after
 700  * suspending (deferred_resume) or wait for it to finish.  If the RPM_ASYNC
 701  * flag is set then queue a resume request; otherwise run the
 702  * ->runtime_resume() callback directly.  Queue an idle notification for the
 703  * device if the resume succeeded.
 704  *
 705  * This function must be called under dev->power.lock with interrupts disabled.
 706  */
 707 static int rpm_resume(struct device *dev, int rpmflags)
 708         __releases(&dev->power.lock) __acquires(&dev->power.lock)
 709 {
 710         int (*callback)(struct device *);
 711         struct device *parent = NULL;
 712         int retval = 0;
 713
 714         trace_rpm_resume_rcuidle(dev, rpmflags);
 715
 716  repeat:
 717         if (dev->power.runtime_error)
 718                 retval = -EINVAL;
 719         else if (dev->power.disable_depth == 1 && dev->power.is_suspended
 720             && dev->power.runtime_status == RPM_ACTIVE)
 721                 retval = 1;
 722         else if (dev->power.disable_depth > 0)
 723                 retval = -EACCES;
 724         if (retval)
 725                 goto out;
 726
 727         /*
 728          * Other scheduled or pending requests need to be canceled.  Small
 729          * optimization: If an autosuspend timer is running, leave it running
 730          * rather than cancelling it now only to restart it again in the near
 731          * future.
 732          */
 733         dev->power.request = RPM_REQ_NONE;
 734         if (!dev->power.timer_autosuspends)
 735                 pm_runtime_deactivate_timer(dev);
 736
 737         if (dev->power.runtime_status == RPM_ACTIVE) {
 738                 retval = 1;
 739                 goto out;
 740         }
 741
 742         if (dev->power.runtime_status == RPM_RESUMING
 743             || dev->power.runtime_status == RPM_SUSPENDING) {
 744                 DEFINE_WAIT(wait);
 745
 746                 if (rpmflags & (RPM_ASYNC | RPM_NOWAIT)) {
 747                         if (dev->power.runtime_status == RPM_SUSPENDING)
 748                                 dev->power.deferred_resume = true;
 749                         else
 750                                 retval = -EINPROGRESS;
 751                         goto out;
 752                 }
 753
 754                 if (dev->power.irq_safe) {
 755                         spin_unlock(&dev->power.lock);
 756
 757                         cpu_relax();
 758
 759                         spin_lock(&dev->power.lock);
 760                         goto repeat;
 761                 }
 762
 763                 /* Wait for the operation carried out in parallel with us. */
 764                 for (;;) {
 765                         prepare_to_wait(&dev->power.wait_queue, &wait,
 766                                         TASK_UNINTERRUPTIBLE);
 767                         if (dev->power.runtime_status != RPM_RESUMING
 768                             && dev->power.runtime_status != RPM_SUSPENDING)
 769                                 break;
 770
 771                         spin_unlock_irq(&dev->power.lock);
 772
 773                         schedule();
 774
 775                         spin_lock_irq(&dev->power.lock);
 776                 }
 777                 finish_wait(&dev->power.wait_queue, &wait);
 778                 goto repeat;
 779         }
 780
 781         /*
 782          * See if we can skip waking up the parent.  This is safe only if
 783          * power.no_callbacks is set, because otherwise we don't know whether
 784          * the resume will actually succeed.
 785          */
 786         if (dev->power.no_callbacks && !parent && dev->parent) {
 787                 spin_lock_nested(&dev->parent->power.lock, SINGLE_DEPTH_NESTING);
 788                 if (dev->parent->power.disable_depth > 0
 789                     || dev->parent->power.ignore_children
 790                     || dev->parent->power.runtime_status == RPM_ACTIVE) {
 791                         atomic_inc(&dev->parent->power.child_count);
 792                         spin_unlock(&dev->parent->power.lock);
 793                         retval = 1;
 794                         goto no_callback;       /* Assume success. */
 795                 }
 796                 spin_unlock(&dev->parent->power.lock);
 797         }
 798
 799         /* Carry out an asynchronous or a synchronous resume. */
 800         if (rpmflags & RPM_ASYNC) {
 801                 dev->power.request = RPM_REQ_RESUME;
 802                 if (!dev->power.request_pending) {
 803                         dev->power.request_pending = true;
 804                         queue_work(pm_wq, &dev->power.work);
 805                 }
 806                 retval = 0;
 807                 goto out;
 808         }
 809
 810         if (!parent && dev->parent) {
 811                 /*
 812                  * Increment the parent's usage counter and resume it if
 813                  * necessary.  Not needed if dev is irq-safe; then the
 814                  * parent is permanently resumed.
 815                  */
 816                 parent = dev->parent;
 817                 if (dev->power.irq_safe)
 818                         goto skip_parent;
 819                 spin_unlock(&dev->power.lock);
 820
 821                 pm_runtime_get_noresume(parent);
 822
 823                 spin_lock(&parent->power.lock);
 824                 /*
 825                  * Resume the parent if it has runtime PM enabled and not been
 826                  * set to ignore its children.
 827                  */
 828                 if (!parent->power.disable_depth
 829                     && !parent->power.ignore_children) {
 830                         rpm_resume(parent, 0);
 831                         if (parent->power.runtime_status != RPM_ACTIVE)
 832                                 retval = -EBUSY;
 833                 }
 834                 spin_unlock(&parent->power.lock);
 835
 836                 spin_lock(&dev->power.lock);
 837                 if (retval)
 838                         goto out;
 839                 goto repeat;
 840         }
 841  skip_parent:
 842
 843         if (dev->power.no_callbacks)
 844                 goto no_callback;       /* Assume success. */
 845
 846         __update_runtime_status(dev, RPM_RESUMING);
 847
 848         callback = RPM_GET_CALLBACK(dev, runtime_resume);
 849
 850         dev_pm_disable_wake_irq_check(dev);
 851         retval = rpm_callback(callback, dev);
 852         if (retval) {
 853                 __update_runtime_status(dev, RPM_SUSPENDED);
 854                 pm_runtime_cancel_pending(dev);
 855                 dev_pm_enable_wake_irq_check(dev, false);
 856         } else {
 857  no_callback:
 858                 __update_runtime_status(dev, RPM_ACTIVE);
 859                 pm_runtime_mark_last_busy(dev);
 860                 if (parent)
 861                         atomic_inc(&parent->power.child_count);
 862         }
 863         wake_up_all(&dev->power.wait_queue);
 864
 865         if (retval >= 0)
 866                 rpm_idle(dev, RPM_ASYNC);
 867
 868  out:
 869         if (parent && !dev->power.irq_safe) {
 870                 spin_unlock_irq(&dev->power.lock);
 871
 872                 pm_runtime_put(parent);
 873
 874                 spin_lock_irq(&dev->power.lock);
 875         }
 876
 877         trace_rpm_return_int_rcuidle(dev, _THIS_IP_, retval);
 878
 879         return retval;
 880 }
 881
 882 /**
 883  * pm_runtime_work - Universal runtime PM work function.
 884  * @work: Work structure used for scheduling the execution of this function.
 885  *
 886  * Use @work to get the device object the work is to be done for, determine what
 887  * is to be done and execute the appropriate runtime PM function.
 888  */
 889 static void pm_runtime_work(struct work_struct *work)
 890 {
 891         struct device *dev = container_of(work, struct device, power.work);
 892         enum rpm_request req;
 893
 894         spin_lock_irq(&dev->power.lock);
 895
 896         if (!dev->power.request_pending)
 897                 goto out;
 898
 899         req = dev->power.request;
 900         dev->power.request = RPM_REQ_NONE;
 901         dev->power.request_pending = false;
 902
 903         switch (req) {
 904         case RPM_REQ_NONE:
 905                 break;
 906         case RPM_REQ_IDLE:
 907                 rpm_idle(dev, RPM_NOWAIT);
 908                 break;
 909         case RPM_REQ_SUSPEND:
 910                 rpm_suspend(dev, RPM_NOWAIT);
 911                 break;
 912         case RPM_REQ_AUTOSUSPEND:
 913                 rpm_suspend(dev, RPM_NOWAIT | RPM_AUTO);
 914                 break;
 915         case RPM_REQ_RESUME:
 916                 rpm_resume(dev, RPM_NOWAIT);
 917                 break;
 918         }
 919
 920  out:
 921         spin_unlock_irq(&dev->power.lock);
 922 }
 923
 924 /**
 925  * pm_suspend_timer_fn - Timer function for pm_schedule_suspend().
 926  * @data: Device pointer passed by pm_schedule_suspend().
 927  *
 928  * Check if the time is right and queue a suspend request.
 929  */
 930 static enum hrtimer_restart  pm_suspend_timer_fn(struct hrtimer *timer)
 931 {
 932         struct device *dev = container_of(timer, struct device, power.suspend_timer);
 933         unsigned long flags;
 934         u64 expires;
 935
 936         spin_lock_irqsave(&dev->power.lock, flags);
 937
 938         expires = dev->power.timer_expires;
 939         /*
 940          * If 'expires' is after the current time, we've been called
 941          * too early.
 942          */
 943         if (expires > 0 && expires < ktime_get_mono_fast_ns()) {
 944                 dev->power.timer_expires = 0;
 945                 rpm_suspend(dev, dev->power.timer_autosuspends ?
 946                     (RPM_ASYNC | RPM_AUTO) : RPM_ASYNC);
 947         }
 948
 949         spin_unlock_irqrestore(&dev->power.lock, flags);
 950
 951         return HRTIMER_NORESTART;
 952 }
 953
 954 /**
 955  * pm_schedule_suspend - Set up a timer to submit a suspend request in future.
 956  * @dev: Device to suspend.
 957  * @delay: Time to wait before submitting a suspend request, in milliseconds.
 958  */
 959 int pm_schedule_suspend(struct device *dev, unsigned int delay)
 960 {
 961         unsigned long flags;
 962         u64 expires;
 963         int retval;
 964
 965         spin_lock_irqsave(&dev->power.lock, flags);
 966
 967         if (!delay) {
 968                 retval = rpm_suspend(dev, RPM_ASYNC);
 969                 goto out;
 970         }
 971
 972         retval = rpm_check_suspend_allowed(dev);
 973         if (retval)
 974                 goto out;
 975
 976         /* Other scheduled or pending requests need to be canceled. */
 977         pm_runtime_cancel_pending(dev);
 978
 979         expires = ktime_get_mono_fast_ns() + (u64)delay * NSEC_PER_MSEC;
 980         dev->power.timer_expires = expires;
 981         dev->power.timer_autosuspends = 0;
 982         hrtimer_start(&dev->power.suspend_timer, expires, HRTIMER_MODE_ABS);
 983
 984  out:
 985         spin_unlock_irqrestore(&dev->power.lock, flags);
 986
 987         return retval;
 988 }
 989 EXPORT_SYMBOL_GPL(pm_schedule_suspend);
 990
 991 /**
 992  * __pm_runtime_idle - Entry point for runtime idle operations.
 993  * @dev: Device to send idle notification for.
 994  * @rpmflags: Flag bits.
 995  *
 996  * If the RPM_GET_PUT flag is set, decrement the device's usage count and
 997  * return immediately if it is larger than zero.  Then carry out an idle
 998  * notification, either synchronous or asynchronous.
 999  *
1000  * This routine may be called in atomic context if the RPM_ASYNC flag is set,
1001  * or if pm_runtime_irq_safe() has been called.
1002  */
1003 int __pm_runtime_idle(struct device *dev, int rpmflags)
1004 {
1005         unsigned long flags;
1006         int retval;
1007
1008         if (rpmflags & RPM_GET_PUT) {
1009                 if (!atomic_dec_and_test(&dev->power.usage_count))
1010                         return 0;
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                         return 0;
1043         }
1044
1045         might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);
1046
1047         spin_lock_irqsave(&dev->power.lock, flags);
1048         retval = rpm_suspend(dev, rpmflags);
1049         spin_unlock_irqrestore(&dev->power.lock, flags);
1050
1051         return retval;
1052 }
1053 EXPORT_SYMBOL_GPL(__pm_runtime_suspend);
1054
1055 /**
1056  * __pm_runtime_resume - Entry point for runtime resume operations.
1057  * @dev: Device to resume.
1058  * @rpmflags: Flag bits.
1059  *
1060  * If the RPM_GET_PUT flag is set, increment the device's usage count.  Then
1061  * carry out a resume, either synchronous or asynchronous.
1062  *
1063  * This routine may be called in atomic context if the RPM_ASYNC flag is set,
1064  * or if pm_runtime_irq_safe() has been called.
1065  */
1066 int __pm_runtime_resume(struct device *dev, int rpmflags)
1067 {
1068         unsigned long flags;
1069         int retval;
1070
1071         might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe &&
1072                         dev->power.runtime_status != RPM_ACTIVE);
1073
1074         if (rpmflags & RPM_GET_PUT)
1075                 atomic_inc(&dev->power.usage_count);
1076
1077         spin_lock_irqsave(&dev->power.lock, flags);
1078         retval = rpm_resume(dev, rpmflags);
1079         spin_unlock_irqrestore(&dev->power.lock, flags);
1080
1081         return retval;
1082 }
1083 EXPORT_SYMBOL_GPL(__pm_runtime_resume);
1084
1085 /**
1086  * pm_runtime_get_if_in_use - Conditionally bump up the device's usage counter.
1087  * @dev: Device to handle.
1088  *
1089  * Return -EINVAL if runtime PM is disabled for the device.
1090  *
1091  * If that's not the case and if the device's runtime PM status is RPM_ACTIVE
1092  * and the runtime PM usage counter is nonzero, increment the counter and
1093  * return 1.  Otherwise return 0 without changing the counter.
1094  */
1095 int pm_runtime_get_if_in_use(struct device *dev)
1096 {
1097         unsigned long flags;
1098         int retval;
1099
1100         spin_lock_irqsave(&dev->power.lock, flags);
1101         retval = dev->power.disable_depth > 0 ? -EINVAL :
1102                 dev->power.runtime_status == RPM_ACTIVE
1103                         && atomic_inc_not_zero(&dev->power.usage_count);
1104         spin_unlock_irqrestore(&dev->power.lock, flags);
1105         return retval;
1106 }
1107 EXPORT_SYMBOL_GPL(pm_runtime_get_if_in_use);
1108
1109 /**
1110  * __pm_runtime_set_status - Set runtime PM status of a device.
1111  * @dev: Device to handle.
1112  * @status: New runtime PM status of the device.
1113  *
1114  * If runtime PM of the device is disabled or its power.runtime_error field is
1115  * different from zero, the status may be changed either to RPM_ACTIVE, or to
1116  * RPM_SUSPENDED, as long as that reflects the actual state of the device.
1117  * However, if the device has a parent and the parent is not active, and the
1118  * parent's power.ignore_children flag is unset, the device's status cannot be
1119  * set to RPM_ACTIVE, so -EBUSY is returned in that case.
1120  *
1121  * If successful, __pm_runtime_set_status() clears the power.runtime_error field
1122  * and the device parent's counter of unsuspended children is modified to
1123  * reflect the new status.  If the new status is RPM_SUSPENDED, an idle
1124  * notification request for the parent is submitted.
1125  *
1126  * If @dev has any suppliers (as reflected by device links to them), and @status
1127  * is RPM_ACTIVE, they will be activated upfront and if the activation of one
1128  * of them fails, the status of @dev will be changed to RPM_SUSPENDED (instead
1129  * of the @status value) and the suppliers will be deacticated on exit.  The
1130  * error returned by the failing supplier activation will be returned in that
1131  * case.
1132  */
1133 int __pm_runtime_set_status(struct device *dev, unsigned int status)
1134 {
1135         struct device *parent = dev->parent;
1136         bool notify_parent = false;
1137         int error = 0;
1138
1139         if (status != RPM_ACTIVE && status != RPM_SUSPENDED)
1140                 return -EINVAL;
1141
1142         spin_lock_irq(&dev->power.lock);
1143
1144         /*
1145          * Prevent PM-runtime from being enabled for the device or return an
1146          * error if it is enabled already and working.
1147          */
1148         if (dev->power.runtime_error || dev->power.disable_depth)
1149                 dev->power.disable_depth++;
1150         else
1151                 error = -EAGAIN;
1152
1153         spin_unlock_irq(&dev->power.lock);
1154
1155         if (error)
1156                 return error;
1157
1158         /*
1159          * If the new status is RPM_ACTIVE, the suppliers can be activated
1160          * upfront regardless of the current status, because next time
1161          * rpm_put_suppliers() runs, the rpm_active refcounts of the links
1162          * involved will be dropped down to one anyway.
1163          */
1164         if (status == RPM_ACTIVE) {
1165                 int idx = device_links_read_lock();
1166
1167                 error = rpm_get_suppliers(dev);
1168                 if (error)
1169                         status = RPM_SUSPENDED;
1170
1171                 device_links_read_unlock(idx);
1172         }
1173
1174         spin_lock_irq(&dev->power.lock);
1175
1176         if (dev->power.runtime_status == status || !parent)
1177                 goto out_set;
1178
1179         if (status == RPM_SUSPENDED) {
1180                 atomic_add_unless(&parent->power.child_count, -1, 0);
1181                 notify_parent = !parent->power.ignore_children;
1182         } else {
1183                 spin_lock_nested(&parent->power.lock, SINGLE_DEPTH_NESTING);
1184
1185                 /*
1186                  * It is invalid to put an active child under a parent that is
1187                  * not active, has runtime PM enabled and the
1188                  * 'power.ignore_children' flag unset.
1189                  */
1190                 if (!parent->power.disable_depth
1191                     && !parent->power.ignore_children
1192                     && parent->power.runtime_status != RPM_ACTIVE) {
1193                         dev_err(dev, "runtime PM trying to activate child device %s but parent (%s) is not active\n",
1194                                 dev_name(dev),
1195                                 dev_name(parent));
1196                         error = -EBUSY;
1197                 } else if (dev->power.runtime_status == RPM_SUSPENDED) {
1198                         atomic_inc(&parent->power.child_count);
1199                 }
1200
1201                 spin_unlock(&parent->power.lock);
1202
1203                 if (error) {
1204                         status = RPM_SUSPENDED;
1205                         goto out;
1206                 }
1207         }
1208
1209  out_set:
1210         __update_runtime_status(dev, status);
1211         if (!error)
1212                 dev->power.runtime_error = 0;
1213
1214  out:
1215         spin_unlock_irq(&dev->power.lock);
1216
1217         if (notify_parent)
1218                 pm_request_idle(parent);
1219
1220         if (status == RPM_SUSPENDED) {
1221                 int idx = device_links_read_lock();
1222
1223                 rpm_put_suppliers(dev);
1224
1225                 device_links_read_unlock(idx);
1226         }
1227
1228         pm_runtime_enable(dev);
1229
1230         return error;
1231 }
1232 EXPORT_SYMBOL_GPL(__pm_runtime_set_status);
1233
1234 /**
1235  * __pm_runtime_barrier - Cancel pending requests and wait for completions.
1236  * @dev: Device to handle.
1237  *
1238  * Flush all pending requests for the device from pm_wq and wait for all
1239  * runtime PM operations involving the device in progress to complete.
1240  *
1241  * Should be called under dev->power.lock with interrupts disabled.
1242  */
1243 static void __pm_runtime_barrier(struct device *dev)
1244 {
1245         pm_runtime_deactivate_timer(dev);
1246
1247         if (dev->power.request_pending) {
1248                 dev->power.request = RPM_REQ_NONE;
1249                 spin_unlock_irq(&dev->power.lock);
1250
1251                 cancel_work_sync(&dev->power.work);
1252
1253                 spin_lock_irq(&dev->power.lock);
1254                 dev->power.request_pending = false;
1255         }
1256
1257         if (dev->power.runtime_status == RPM_SUSPENDING
1258             || dev->power.runtime_status == RPM_RESUMING
1259             || dev->power.idle_notification) {
1260                 DEFINE_WAIT(wait);
1261
1262                 /* Suspend, wake-up or idle notification in progress. */
1263                 for (;;) {
1264                         prepare_to_wait(&dev->power.wait_queue, &wait,
1265                                         TASK_UNINTERRUPTIBLE);
1266                         if (dev->power.runtime_status != RPM_SUSPENDING
1267                             && dev->power.runtime_status != RPM_RESUMING
1268                             && !dev->power.idle_notification)
1269                                 break;
1270                         spin_unlock_irq(&dev->power.lock);
1271
1272                         schedule();
1273
1274                         spin_lock_irq(&dev->power.lock);
1275                 }
1276                 finish_wait(&dev->power.wait_queue, &wait);
1277         }
1278 }
1279
1280 /**
1281  * pm_runtime_barrier - Flush pending requests and wait for completions.
1282  * @dev: Device to handle.
1283  *
1284  * Prevent the device from being suspended by incrementing its usage counter and
1285  * if there's a pending resume request for the device, wake the device up.
1286  * Next, make sure that all pending requests for the device have been flushed
1287  * from pm_wq and wait for all runtime PM operations involving the device in
1288  * progress to complete.
1289  *
1290  * Return value:
1291  * 1, if there was a resume request pending and the device had to be woken up,
1292  * 0, otherwise
1293  */
1294 int pm_runtime_barrier(struct device *dev)
1295 {
1296         int retval = 0;
1297
1298         pm_runtime_get_noresume(dev);
1299         spin_lock_irq(&dev->power.lock);
1300
1301         if (dev->power.request_pending
1302             && dev->power.request == RPM_REQ_RESUME) {
1303                 rpm_resume(dev, 0);
1304                 retval = 1;
1305         }
1306
1307         __pm_runtime_barrier(dev);
1308
1309         spin_unlock_irq(&dev->power.lock);
1310         pm_runtime_put_noidle(dev);
1311
1312         return retval;
1313 }
1314 EXPORT_SYMBOL_GPL(pm_runtime_barrier);
1315
1316 /**
1317  * __pm_runtime_disable - Disable runtime PM of a device.
1318  * @dev: Device to handle.
1319  * @check_resume: If set, check if there's a resume request for the device.
1320  *
1321  * Increment power.disable_depth for the device and if it was zero previously,
1322  * cancel all pending runtime PM requests for the device and wait for all
1323  * operations in progress to complete.  The device can be either active or
1324  * suspended after its runtime PM has been disabled.
1325  *
1326  * If @check_resume is set and there's a resume request pending when
1327  * __pm_runtime_disable() is called and power.disable_depth is zero, the
1328  * function will wake up the device before disabling its runtime PM.
1329  */
1330 void __pm_runtime_disable(struct device *dev, bool check_resume)
1331 {
1332         spin_lock_irq(&dev->power.lock);
1333
1334         if (dev->power.disable_depth > 0) {
1335                 dev->power.disable_depth++;
1336                 goto out;
1337         }
1338
1339         /*
1340          * Wake up the device if there's a resume request pending, because that
1341          * means there probably is some I/O to process and disabling runtime PM
1342          * shouldn't prevent the device from processing the I/O.
1343          */
1344         if (check_resume && dev->power.request_pending
1345             && dev->power.request == RPM_REQ_RESUME) {
1346                 /*
1347                  * Prevent suspends and idle notifications from being carried
1348                  * out after we have woken up the device.
1349                  */
1350                 pm_runtime_get_noresume(dev);
1351
1352                 rpm_resume(dev, 0);
1353
1354                 pm_runtime_put_noidle(dev);
1355         }
1356
1357         /* Update time accounting before disabling PM-runtime. */
1358         update_pm_runtime_accounting(dev);
1359
1360         if (!dev->power.disable_depth++)
1361                 __pm_runtime_barrier(dev);
1362
1363  out:
1364         spin_unlock_irq(&dev->power.lock);
1365 }
1366 EXPORT_SYMBOL_GPL(__pm_runtime_disable);
1367
1368 /**
1369  * pm_runtime_enable - Enable runtime PM of a device.
1370  * @dev: Device to handle.
1371  */
1372 void pm_runtime_enable(struct device *dev)
1373 {
1374         unsigned long flags;
1375
1376         spin_lock_irqsave(&dev->power.lock, flags);
1377
1378         if (dev->power.disable_depth > 0) {
1379                 dev->power.disable_depth--;
1380
1381                 /* About to enable runtime pm, set accounting_timestamp to now */
1382                 if (!dev->power.disable_depth)
1383                         dev->power.accounting_timestamp = ktime_get_mono_fast_ns();
1384         } else {
1385                 dev_warn(dev, "Unbalanced %s!\n", __func__);
1386         }
1387
1388         WARN(!dev->power.disable_depth &&
1389              dev->power.runtime_status == RPM_SUSPENDED &&
1390              !dev->power.ignore_children &&
1391              atomic_read(&dev->power.child_count) > 0,
1392              "Enabling runtime PM for inactive device (%s) with active children\n",
1393              dev_name(dev));
1394
1395         spin_unlock_irqrestore(&dev->power.lock, flags);
1396 }
1397 EXPORT_SYMBOL_GPL(pm_runtime_enable);
1398
1399 /**
1400  * pm_runtime_forbid - Block runtime PM of a device.
1401  * @dev: Device to handle.
1402  *
1403  * Increase the device's usage count and clear its power.runtime_auto flag,
1404  * so that it cannot be suspended at run time until pm_runtime_allow() is called
1405  * for it.
1406  */
1407 void pm_runtime_forbid(struct device *dev)
1408 {
1409         spin_lock_irq(&dev->power.lock);
1410         if (!dev->power.runtime_auto)
1411                 goto out;
1412
1413         dev->power.runtime_auto = false;
1414         atomic_inc(&dev->power.usage_count);
1415         rpm_resume(dev, 0);
1416
1417  out:
1418         spin_unlock_irq(&dev->power.lock);
1419 }
1420 EXPORT_SYMBOL_GPL(pm_runtime_forbid);
1421
1422 /**
1423  * pm_runtime_allow - Unblock runtime PM of a device.
1424  * @dev: Device to handle.
1425  *
1426  * Decrease the device's usage count and set its power.runtime_auto flag.
1427  */
1428 void pm_runtime_allow(struct device *dev)
1429 {
1430         spin_lock_irq(&dev->power.lock);
1431         if (dev->power.runtime_auto)
1432                 goto out;
1433
1434         dev->power.runtime_auto = true;
1435         if (atomic_dec_and_test(&dev->power.usage_count))
1436                 rpm_idle(dev, RPM_AUTO | RPM_ASYNC);
1437
1438  out:
1439         spin_unlock_irq(&dev->power.lock);
1440 }
1441 EXPORT_SYMBOL_GPL(pm_runtime_allow);
1442
1443 /**
1444  * pm_runtime_no_callbacks - Ignore runtime PM callbacks for a device.
1445  * @dev: Device to handle.
1446  *
1447  * Set the power.no_callbacks flag, which tells the PM core that this
1448  * device is power-managed through its parent and has no runtime PM
1449  * callbacks of its own.  The runtime sysfs attributes will be removed.
1450  */
1451 void pm_runtime_no_callbacks(struct device *dev)
1452 {
1453         spin_lock_irq(&dev->power.lock);
1454         dev->power.no_callbacks = 1;
1455         spin_unlock_irq(&dev->power.lock);
1456         if (device_is_registered(dev))
1457                 rpm_sysfs_remove(dev);
1458 }
1459 EXPORT_SYMBOL_GPL(pm_runtime_no_callbacks);
1460
1461 /**
1462  * pm_runtime_irq_safe - Leave interrupts disabled during callbacks.
1463  * @dev: Device to handle
1464  *
1465  * Set the power.irq_safe flag, which tells the PM core that the
1466  * ->runtime_suspend() and ->runtime_resume() callbacks for this device should
1467  * always be invoked with the spinlock held and interrupts disabled.  It also
1468  * causes the parent's usage counter to be permanently incremented, preventing
1469  * the parent from runtime suspending -- otherwise an irq-safe child might have
1470  * to wait for a non-irq-safe parent.
1471  */
1472 void pm_runtime_irq_safe(struct device *dev)
1473 {
1474         if (dev->parent)
1475                 pm_runtime_get_sync(dev->parent);
1476         spin_lock_irq(&dev->power.lock);
1477         dev->power.irq_safe = 1;
1478         spin_unlock_irq(&dev->power.lock);
1479 }
1480 EXPORT_SYMBOL_GPL(pm_runtime_irq_safe);
1481
1482 /**
1483  * update_autosuspend - Handle a change to a device's autosuspend settings.
1484  * @dev: Device to handle.
1485  * @old_delay: The former autosuspend_delay value.
1486  * @old_use: The former use_autosuspend value.
1487  *
1488  * Prevent runtime suspend if the new delay is negative and use_autosuspend is
1489  * set; otherwise allow it.  Send an idle notification if suspends are allowed.
1490  *
1491  * This function must be called under dev->power.lock with interrupts disabled.
1492  */
1493 static void update_autosuspend(struct device *dev, int old_delay, int old_use)
1494 {
1495         int delay = dev->power.autosuspend_delay;
1496
1497         /* Should runtime suspend be prevented now? */
1498         if (dev->power.use_autosuspend && delay < 0) {
1499
1500                 /* If it used to be allowed then prevent it. */
1501                 if (!old_use || old_delay >= 0) {
1502                         atomic_inc(&dev->power.usage_count);
1503                         rpm_resume(dev, 0);
1504                 }
1505         }
1506
1507         /* Runtime suspend should be allowed now. */
1508         else {
1509
1510                 /* If it used to be prevented then allow it. */
1511                 if (old_use && old_delay < 0)
1512                         atomic_dec(&dev->power.usage_count);
1513
1514                 /* Maybe we can autosuspend now. */
1515                 rpm_idle(dev, RPM_AUTO);
1516         }
1517 }
1518
1519 /**
1520  * pm_runtime_set_autosuspend_delay - Set a device's autosuspend_delay value.
1521  * @dev: Device to handle.
1522  * @delay: Value of the new delay in milliseconds.
1523  *
1524  * Set the device's power.autosuspend_delay value.  If it changes to negative
1525  * and the power.use_autosuspend flag is set, prevent runtime suspends.  If it
1526  * changes the other way, allow runtime suspends.
1527  */
1528 void pm_runtime_set_autosuspend_delay(struct device *dev, int delay)
1529 {
1530         int old_delay, old_use;
1531
1532         spin_lock_irq(&dev->power.lock);
1533         old_delay = dev->power.autosuspend_delay;
1534         old_use = dev->power.use_autosuspend;
1535         dev->power.autosuspend_delay = delay;
1536         update_autosuspend(dev, old_delay, old_use);
1537         spin_unlock_irq(&dev->power.lock);
1538 }
1539 EXPORT_SYMBOL_GPL(pm_runtime_set_autosuspend_delay);
1540
1541 /**
1542  * __pm_runtime_use_autosuspend - Set a device's use_autosuspend flag.
1543  * @dev: Device to handle.
1544  * @use: New value for use_autosuspend.
1545  *
1546  * Set the device's power.use_autosuspend flag, and allow or prevent runtime
1547  * suspends as needed.
1548  */
1549 void __pm_runtime_use_autosuspend(struct device *dev, bool use)
1550 {
1551         int old_delay, old_use;
1552
1553         spin_lock_irq(&dev->power.lock);
1554         old_delay = dev->power.autosuspend_delay;
1555         old_use = dev->power.use_autosuspend;
1556         dev->power.use_autosuspend = use;
1557         update_autosuspend(dev, old_delay, old_use);
1558         spin_unlock_irq(&dev->power.lock);
1559 }
1560 EXPORT_SYMBOL_GPL(__pm_runtime_use_autosuspend);
1561
1562 /**
1563  * pm_runtime_init - Initialize runtime PM fields in given device object.
1564  * @dev: Device object to initialize.
1565  */
1566 void pm_runtime_init(struct device *dev)
1567 {
1568         dev->power.runtime_status = RPM_SUSPENDED;
1569         dev->power.idle_notification = false;
1570
1571         dev->power.disable_depth = 1;
1572         atomic_set(&dev->power.usage_count, 0);
1573
1574         dev->power.runtime_error = 0;
1575
1576         atomic_set(&dev->power.child_count, 0);
1577         pm_suspend_ignore_children(dev, false);
1578         dev->power.runtime_auto = true;
1579
1580         dev->power.request_pending = false;
1581         dev->power.request = RPM_REQ_NONE;
1582         dev->power.deferred_resume = false;
1583         INIT_WORK(&dev->power.work, pm_runtime_work);
1584
1585         dev->power.timer_expires = 0;
1586         hrtimer_init(&dev->power.suspend_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
1587         dev->power.suspend_timer.function = pm_suspend_timer_fn;
1588
1589         init_waitqueue_head(&dev->power.wait_queue);
1590 }
1591
1592 /**
1593  * pm_runtime_reinit - Re-initialize runtime PM fields in given device object.
1594  * @dev: Device object to re-initialize.
1595  */
1596 void pm_runtime_reinit(struct device *dev)
1597 {
1598         if (!pm_runtime_enabled(dev)) {
1599                 if (dev->power.runtime_status == RPM_ACTIVE)
1600                         pm_runtime_set_suspended(dev);
1601                 if (dev->power.irq_safe) {
1602                         spin_lock_irq(&dev->power.lock);
1603                         dev->power.irq_safe = 0;
1604                         spin_unlock_irq(&dev->power.lock);
1605                         if (dev->parent)
1606                                 pm_runtime_put(dev->parent);
1607                 }
1608         }
1609 }
1610
1611 /**
1612  * pm_runtime_remove - Prepare for removing a device from device hierarchy.
1613  * @dev: Device object being removed from device hierarchy.
1614  */
1615 void pm_runtime_remove(struct device *dev)
1616 {
1617         __pm_runtime_disable(dev, false);
1618         pm_runtime_reinit(dev);
1619 }
1620
1621 /**
1622  * pm_runtime_clean_up_links - Prepare links to consumers for driver removal.
1623  * @dev: Device whose driver is going to be removed.
1624  *
1625  * Check links from this device to any consumers and if any of them have active
1626  * runtime PM references to the device, drop the usage counter of the device
1627  * (as many times as needed).
1628  *
1629  * Links with the DL_FLAG_MANAGED flag unset are ignored.
1630  *
1631  * Since the device is guaranteed to be runtime-active at the point this is
1632  * called, nothing else needs to be done here.
1633  *
1634  * Moreover, this is called after device_links_busy() has returned 'false', so
1635  * the status of each link is guaranteed to be DL_STATE_SUPPLIER_UNBIND and
1636  * therefore rpm_active can't be manipulated concurrently.
1637  */
1638 void pm_runtime_clean_up_links(struct device *dev)
1639 {
1640         struct device_link *link;
1641         int idx;
1642
1643         idx = device_links_read_lock();
1644
1645         list_for_each_entry_rcu(link, &dev->links.consumers, s_node,
1646                                 device_links_read_lock_held()) {
1647                 if (!(link->flags & DL_FLAG_MANAGED))
1648                         continue;
1649
1650                 while (refcount_dec_not_one(&link->rpm_active))
1651                         pm_runtime_put_noidle(dev);
1652         }
1653
1654         device_links_read_unlock(idx);
1655 }
1656
1657 /**
1658  * pm_runtime_get_suppliers - Resume and reference-count supplier devices.
1659  * @dev: Consumer device.
1660  */
1661 void pm_runtime_get_suppliers(struct device *dev)
1662 {
1663         struct device_link *link;
1664         int idx;
1665
1666         idx = device_links_read_lock();
1667
1668         list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
1669                                 device_links_read_lock_held())
1670                 if (link->flags & DL_FLAG_PM_RUNTIME) {
1671                         link->supplier_preactivated = true;
1672                         refcount_inc(&link->rpm_active);
1673                         pm_runtime_get_sync(link->supplier);
1674                 }
1675
1676         device_links_read_unlock(idx);
1677 }
1678
1679 /**
1680  * pm_runtime_put_suppliers - Drop references to supplier devices.
1681  * @dev: Consumer device.
1682  */
1683 void pm_runtime_put_suppliers(struct device *dev)
1684 {
1685         struct device_link *link;
1686         int idx;
1687
1688         idx = device_links_read_lock();
1689
1690         list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
1691                                 device_links_read_lock_held())
1692                 if (link->supplier_preactivated) {
1693                         link->supplier_preactivated = false;
1694                         if (refcount_dec_not_one(&link->rpm_active))
1695                                 pm_runtime_put(link->supplier);
1696                 }
1697
1698         device_links_read_unlock(idx);
1699 }
1700
1701 void pm_runtime_new_link(struct device *dev)
1702 {
1703         spin_lock_irq(&dev->power.lock);
1704         dev->power.links_count++;
1705         spin_unlock_irq(&dev->power.lock);
1706 }
1707
1708 void pm_runtime_drop_link(struct device *dev)
1709 {
1710         spin_lock_irq(&dev->power.lock);
1711         WARN_ON(dev->power.links_count == 0);
1712         dev->power.links_count--;
1713         spin_unlock_irq(&dev->power.lock);
1714 }
1715
1716 static bool pm_runtime_need_not_resume(struct device *dev)
1717 {
1718         return atomic_read(&dev->power.usage_count) <= 1 &&
1719                 (atomic_read(&dev->power.child_count) == 0 ||
1720                  dev->power.ignore_children);
1721 }
1722
1723 /**
1724  * pm_runtime_force_suspend - Force a device into suspend state if needed.
1725  * @dev: Device to suspend.
1726  *
1727  * Disable runtime PM so we safely can check the device's runtime PM status and
1728  * if it is active, invoke its ->runtime_suspend callback to suspend it and
1729  * change its runtime PM status field to RPM_SUSPENDED.  Also, if the device's
1730  * usage and children counters don't indicate that the device was in use before
1731  * the system-wide transition under way, decrement its parent's children counter
1732  * (if there is a parent).  Keep runtime PM disabled to preserve the state
1733  * unless we encounter errors.
1734  *
1735  * Typically this function may be invoked from a system suspend callback to make
1736  * sure the device is put into low power state and it should only be used during
1737  * system-wide PM transitions to sleep states.  It assumes that the analogous
1738  * pm_runtime_force_resume() will be used to resume the device.
1739  */
1740 int pm_runtime_force_suspend(struct device *dev)
1741 {
1742         int (*callback)(struct device *);
1743         int ret;
1744
1745         pm_runtime_disable(dev);
1746         if (pm_runtime_status_suspended(dev))
1747                 return 0;
1748
1749         callback = RPM_GET_CALLBACK(dev, runtime_suspend);
1750
1751         ret = callback ? callback(dev) : 0;
1752         if (ret)
1753                 goto err;
1754
1755         /*
1756          * If the device can stay in suspend after the system-wide transition
1757          * to the working state that will follow, drop the children counter of
1758          * its parent, but set its status to RPM_SUSPENDED anyway in case this
1759          * function will be called again for it in the meantime.
1760          */
1761         if (pm_runtime_need_not_resume(dev))
1762                 pm_runtime_set_suspended(dev);
1763         else
1764                 __update_runtime_status(dev, RPM_SUSPENDED);
1765
1766         return 0;
1767
1768 err:
1769         pm_runtime_enable(dev);
1770         return ret;
1771 }
1772 EXPORT_SYMBOL_GPL(pm_runtime_force_suspend);
1773
1774 /**
1775  * pm_runtime_force_resume - Force a device into resume state if needed.
1776  * @dev: Device to resume.
1777  *
1778  * Prior invoking this function we expect the user to have brought the device
1779  * into low power state by a call to pm_runtime_force_suspend(). Here we reverse
1780  * those actions and bring the device into full power, if it is expected to be
1781  * used on system resume.  In the other case, we defer the resume to be managed
1782  * via runtime PM.
1783  *
1784  * Typically this function may be invoked from a system resume callback.
1785  */
1786 int pm_runtime_force_resume(struct device *dev)
1787 {
1788         int (*callback)(struct device *);
1789         int ret = 0;
1790
1791         if (!pm_runtime_status_suspended(dev) || pm_runtime_need_not_resume(dev))
1792                 goto out;
1793
1794         /*
1795          * The value of the parent's children counter is correct already, so
1796          * just update the status of the device.
1797          */
1798         __update_runtime_status(dev, RPM_ACTIVE);
1799
1800         callback = RPM_GET_CALLBACK(dev, runtime_resume);
1801
1802         ret = callback ? callback(dev) : 0;
1803         if (ret) {
1804                 pm_runtime_set_suspended(dev);
1805                 goto out;
1806         }
1807
1808         pm_runtime_mark_last_busy(dev);
1809 out:
1810         pm_runtime_enable(dev);
1811         return ret;
1812 }
1813 EXPORT_SYMBOL_GPL(pm_runtime_force_resume);