drivers/base/power/runtime.c

   1 /*
   2  * drivers/base/power/runtime.c - Helper functions for device runtime PM
   3  *
   4  * Copyright (c) 2009 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
   5  * Copyright (C) 2010 Alan Stern <stern@rowland.harvard.edu>
   6  *
   7  * This file is released under the GPLv2.
   8  */
   9
  10 #include <linux/sched.h>
  11 #include <linux/export.h>
  12 #include <linux/pm_runtime.h>
  13 #include <trace/events/rpm.h>
  14 #include "power.h"
  15
  16 static int rpm_resume(struct device *dev, int rpmflags);
  17 static int rpm_suspend(struct device *dev, int rpmflags);
  18
  19 /**
  20  * update_pm_runtime_accounting - Update the time accounting of power states
  21  * @dev: Device to update the accounting for
  22  *
  23  * In order to be able to have time accounting of the various power states
  24  * (as used by programs such as PowerTOP to show the effectiveness of runtime
  25  * PM), we need to track the time spent in each state.
  26  * update_pm_runtime_accounting must be called each time before the
  27  * runtime_status field is updated, to account the time in the old state
  28  * correctly.
  29  */
  30 void update_pm_runtime_accounting(struct device *dev)
  31 {
  32         unsigned long now = jiffies;
  33         unsigned long delta;
  34
  35         delta = now - dev->power.accounting_timestamp;
  36
  37         dev->power.accounting_timestamp = now;
  38
  39         if (dev->power.disable_depth > 0)
  40                 return;
  41
  42         if (dev->power.runtime_status == RPM_SUSPENDED)
  43                 dev->power.suspended_jiffies += delta;
  44         else
  45                 dev->power.active_jiffies += delta;
  46 }
  47
  48 static void __update_runtime_status(struct device *dev, enum rpm_status status)
  49 {
  50         update_pm_runtime_accounting(dev);
  51         dev->power.runtime_status = status;
  52 }
  53
  54 /**
  55  * pm_runtime_deactivate_timer - Deactivate given device's suspend timer.
  56  * @dev: Device to handle.
  57  */
  58 static void pm_runtime_deactivate_timer(struct device *dev)
  59 {
  60         if (dev->power.timer_expires > 0) {
  61                 del_timer(&dev->power.suspend_timer);
  62                 dev->power.timer_expires = 0;
  63         }
  64 }
  65
  66 /**
  67  * pm_runtime_cancel_pending - Deactivate suspend timer and cancel requests.
  68  * @dev: Device to handle.
  69  */
  70 static void pm_runtime_cancel_pending(struct device *dev)
  71 {
  72         pm_runtime_deactivate_timer(dev);
  73         /*
  74          * In case there's a request pending, make sure its work function will
  75          * return without doing anything.
  76          */
  77         dev->power.request = RPM_REQ_NONE;
  78 }
  79
  80 /*
  81  * pm_runtime_autosuspend_expiration - Get a device's autosuspend-delay expiration time.
  82  * @dev: Device to handle.
  83  *
  84  * Compute the autosuspend-delay expiration time based on the device's
  85  * power.last_busy time.  If the delay has already expired or is disabled
  86  * (negative) or the power.use_autosuspend flag isn't set, return 0.
  87  * Otherwise return the expiration time in jiffies (adjusted to be nonzero).
  88  *
  89  * This function may be called either with or without dev->power.lock held.
  90  * Either way it can be racy, since power.last_busy may be updated at any time.
  91  */
  92 unsigned long pm_runtime_autosuspend_expiration(struct device *dev)
  93 {
  94         int autosuspend_delay;
  95         long elapsed;
  96         unsigned long last_busy;
  97         unsigned long expires = 0;
  98
  99         if (!dev->power.use_autosuspend)
 100                 goto out;
 101
 102         autosuspend_delay = ACCESS_ONCE(dev->power.autosuspend_delay);
 103         if (autosuspend_delay < 0)
 104                 goto out;
 105
 106         last_busy = ACCESS_ONCE(dev->power.last_busy);
 107         elapsed = jiffies - last_busy;
 108         if (elapsed < 0)
 109                 goto out;       /* jiffies has wrapped around. */
 110
 111         /*
 112          * If the autosuspend_delay is >= 1 second, align the timer by rounding
 113          * up to the nearest second.
 114          */
 115         expires = last_busy + msecs_to_jiffies(autosuspend_delay);
 116         if (autosuspend_delay >= 1000)
 117                 expires = round_jiffies(expires);
 118         expires += !expires;
 119         if (elapsed >= expires - last_busy)
 120                 expires = 0;    /* Already expired. */
 121
 122  out:
 123         return expires;
 124 }
 125 EXPORT_SYMBOL_GPL(pm_runtime_autosuspend_expiration);
 126
 127 static int dev_memalloc_noio(struct device *dev, void *data)
 128 {
 129         return dev->power.memalloc_noio;
 130 }
 131
 132 /*
 133  * pm_runtime_set_memalloc_noio - Set a device's memalloc_noio flag.
 134  * @dev: Device to handle.
 135  * @enable: True for setting the flag and False for clearing the flag.
 136  *
 137  * Set the flag for all devices in the path from the device to the
 138  * root device in the device tree if @enable is true, otherwise clear
 139  * the flag for devices in the path whose siblings don't set the flag.
 140  *
 141  * The function should only be called by block device, or network
 142  * device driver for solving the deadlock problem during runtime
 143  * resume/suspend:
 144  *
 145  *     If memory allocation with GFP_KERNEL is called inside runtime
 146  *     resume/suspend callback of any one of its ancestors(or the
 147  *     block device itself), the deadlock may be triggered inside the
 148  *     memory allocation since it might not complete until the block
 149  *     device becomes active and the involed page I/O finishes. The
 150  *     situation is pointed out first by Alan Stern. Network device
 151  *     are involved in iSCSI kind of situation.
 152  *
 153  * The lock of dev_hotplug_mutex is held in the function for handling
 154  * hotplug race because pm_runtime_set_memalloc_noio() may be called
 155  * in async probe().
 156  *
 157  * The function should be called between device_add() and device_del()
 158  * on the affected device(block/network device).
 159  */
 160 void pm_runtime_set_memalloc_noio(struct device *dev, bool enable)
 161 {
 162         static DEFINE_MUTEX(dev_hotplug_mutex);
 163
 164         mutex_lock(&dev_hotplug_mutex);
 165         for (;;) {
 166                 bool enabled;
 167
 168                 /* hold power lock since bitfield is not SMP-safe. */
 169                 spin_lock_irq(&dev->power.lock);
 170                 enabled = dev->power.memalloc_noio;
 171                 dev->power.memalloc_noio = enable;
 172                 spin_unlock_irq(&dev->power.lock);
 173
 174                 /*
 175                  * not need to enable ancestors any more if the device
 176                  * has been enabled.
 177                  */
 178                 if (enabled && enable)
 179                         break;
 180
 181                 dev = dev->parent;
 182
 183                 /*
 184                  * clear flag of the parent device only if all the
 185                  * children don't set the flag because ancestor's
 186                  * flag was set by any one of the descendants.
 187                  */
 188                 if (!dev || (!enable &&
 189                              device_for_each_child(dev, NULL,
 190                                                    dev_memalloc_noio)))
 191                         break;
 192         }
 193         mutex_unlock(&dev_hotplug_mutex);
 194 }
 195 EXPORT_SYMBOL_GPL(pm_runtime_set_memalloc_noio);
 196
 197 /**
 198  * rpm_check_suspend_allowed - Test whether a device may be suspended.
 199  * @dev: Device to test.
 200  */
 201 static int rpm_check_suspend_allowed(struct device *dev)
 202 {
 203         int retval = 0;
 204
 205         if (dev->power.runtime_error)
 206                 retval = -EINVAL;
 207         else if (dev->power.disable_depth > 0)
 208                 retval = -EACCES;
 209         else if (atomic_read(&dev->power.usage_count) > 0)
 210                 retval = -EAGAIN;
 211         else if (!pm_children_suspended(dev))
 212                 retval = -EBUSY;
 213
 214         /* Pending resume requests take precedence over suspends. */
 215         else if ((dev->power.deferred_resume
 216                         && dev->power.runtime_status == RPM_SUSPENDING)
 217             || (dev->power.request_pending
 218                         && dev->power.request == RPM_REQ_RESUME))
 219                 retval = -EAGAIN;
 220         else if (__dev_pm_qos_read_value(dev) < 0)
 221                 retval = -EPERM;
 222         else if (dev->power.runtime_status == RPM_SUSPENDED)
 223                 retval = 1;
 224
 225         return retval;
 226 }
 227
 228 /**
 229  * __rpm_callback - Run a given runtime PM callback for a given device.
 230  * @cb: Runtime PM callback to run.
 231  * @dev: Device to run the callback for.
 232  */
 233 static int __rpm_callback(int (*cb)(struct device *), struct device *dev)
 234         __releases(&dev->power.lock) __acquires(&dev->power.lock)
 235 {
 236         int retval;
 237
 238         if (dev->power.irq_safe)
 239                 spin_unlock(&dev->power.lock);
 240         else
 241                 spin_unlock_irq(&dev->power.lock);
 242
 243         retval = cb(dev);
 244
 245         if (dev->power.irq_safe)
 246                 spin_lock(&dev->power.lock);
 247         else
 248                 spin_lock_irq(&dev->power.lock);
 249
 250         return retval;
 251 }
 252
 253 /**
 254  * rpm_idle - Notify device bus type if the device can be suspended.
 255  * @dev: Device to notify the bus type about.
 256  * @rpmflags: Flag bits.
 257  *
 258  * Check if the device's runtime PM status allows it to be suspended.  If
 259  * another idle notification has been started earlier, return immediately.  If
 260  * the RPM_ASYNC flag is set then queue an idle-notification request; otherwise
 261  * run the ->runtime_idle() callback directly.
 262  *
 263  * This function must be called under dev->power.lock with interrupts disabled.
 264  */
 265 static int rpm_idle(struct device *dev, int rpmflags)
 266 {
 267         int (*callback)(struct device *);
 268         int retval;
 269
 270         trace_rpm_idle(dev, rpmflags);
 271         retval = rpm_check_suspend_allowed(dev);
 272         if (retval < 0)
 273                 ;       /* Conditions are wrong. */
 274
 275         /* Idle notifications are allowed only in the RPM_ACTIVE state. */
 276         else if (dev->power.runtime_status != RPM_ACTIVE)
 277                 retval = -EAGAIN;
 278
 279         /*
 280          * Any pending request other than an idle notification takes
 281          * precedence over us, except that the timer may be running.
 282          */
 283         else if (dev->power.request_pending &&
 284             dev->power.request > RPM_REQ_IDLE)
 285                 retval = -EAGAIN;
 286
 287         /* Act as though RPM_NOWAIT is always set. */
 288         else if (dev->power.idle_notification)
 289                 retval = -EINPROGRESS;
 290         if (retval)
 291                 goto out;
 292
 293         /* Pending requests need to be canceled. */
 294         dev->power.request = RPM_REQ_NONE;
 295
 296         if (dev->power.no_callbacks)
 297                 goto out;
 298
 299         /* Carry out an asynchronous or a synchronous idle notification. */
 300         if (rpmflags & RPM_ASYNC) {
 301                 dev->power.request = RPM_REQ_IDLE;
 302                 if (!dev->power.request_pending) {
 303                         dev->power.request_pending = true;
 304                         queue_work(pm_wq, &dev->power.work);
 305                 }
 306                 trace_rpm_return_int(dev, _THIS_IP_, 0);
 307                 return 0;
 308         }
 309
 310         dev->power.idle_notification = true;
 311
 312         if (dev->pm_domain)
 313                 callback = dev->pm_domain->ops.runtime_idle;
 314         else if (dev->type && dev->type->pm)
 315                 callback = dev->type->pm->runtime_idle;
 316         else if (dev->class && dev->class->pm)
 317                 callback = dev->class->pm->runtime_idle;
 318         else if (dev->bus && dev->bus->pm)
 319                 callback = dev->bus->pm->runtime_idle;
 320         else
 321                 callback = NULL;
 322
 323         if (!callback && dev->driver && dev->driver->pm)
 324                 callback = dev->driver->pm->runtime_idle;
 325
 326         if (callback)
 327                 retval = __rpm_callback(callback, dev);
 328
 329         dev->power.idle_notification = false;
 330         wake_up_all(&dev->power.wait_queue);
 331
 332  out:
 333         trace_rpm_return_int(dev, _THIS_IP_, retval);
 334         return retval ? retval : rpm_suspend(dev, rpmflags);
 335 }
 336
 337 /**
 338  * rpm_callback - Run a given runtime PM callback for a given device.
 339  * @cb: Runtime PM callback to run.
 340  * @dev: Device to run the callback for.
 341  */
 342 static int rpm_callback(int (*cb)(struct device *), struct device *dev)
 343 {
 344         int retval;
 345
 346         if (!cb)
 347                 return -ENOSYS;
 348
 349         if (dev->power.memalloc_noio) {
 350                 unsigned int noio_flag;
 351
 352                 /*
 353                  * Deadlock might be caused if memory allocation with
 354                  * GFP_KERNEL happens inside runtime_suspend and
 355                  * runtime_resume callbacks of one block device's
 356                  * ancestor or the block device itself. Network
 357                  * device might be thought as part of iSCSI block
 358                  * device, so network device and its ancestor should
 359                  * be marked as memalloc_noio too.
 360                  */
 361                 noio_flag = memalloc_noio_save();
 362                 retval = __rpm_callback(cb, dev);
 363                 memalloc_noio_restore(noio_flag);
 364         } else {
 365                 retval = __rpm_callback(cb, dev);
 366         }
 367
 368         dev->power.runtime_error = retval;
 369         return retval != -EACCES ? retval : -EIO;
 370 }
 371
 372 /**
 373  * rpm_suspend - Carry out runtime suspend of given device.
 374  * @dev: Device to suspend.
 375  * @rpmflags: Flag bits.
 376  *
 377  * Check if the device's runtime PM status allows it to be suspended.
 378  * Cancel a pending idle notification, autosuspend or suspend. If
 379  * another suspend has been started earlier, either return immediately
 380  * or wait for it to finish, depending on the RPM_NOWAIT and RPM_ASYNC
 381  * flags. If the RPM_ASYNC flag is set then queue a suspend request;
 382  * otherwise run the ->runtime_suspend() callback directly. When
 383  * ->runtime_suspend succeeded, if a deferred resume was requested while
 384  * the callback was running then carry it out, otherwise send an idle
 385  * notification for its parent (if the suspend succeeded and both
 386  * ignore_children of parent->power and irq_safe of dev->power are not set).
 387  * If ->runtime_suspend failed with -EAGAIN or -EBUSY, and if the RPM_AUTO
 388  * flag is set and the next autosuspend-delay expiration time is in the
 389  * future, schedule another autosuspend attempt.
 390  *
 391  * This function must be called under dev->power.lock with interrupts disabled.
 392  */
 393 static int rpm_suspend(struct device *dev, int rpmflags)
 394         __releases(&dev->power.lock) __acquires(&dev->power.lock)
 395 {
 396         int (*callback)(struct device *);
 397         struct device *parent = NULL;
 398         int retval;
 399
 400         trace_rpm_suspend(dev, rpmflags);
 401
 402  repeat:
 403         retval = rpm_check_suspend_allowed(dev);
 404
 405         if (retval < 0)
 406                 ;       /* Conditions are wrong. */
 407
 408         /* Synchronous suspends are not allowed in the RPM_RESUMING state. */
 409         else if (dev->power.runtime_status == RPM_RESUMING &&
 410             !(rpmflags & RPM_ASYNC))
 411                 retval = -EAGAIN;
 412         if (retval)
 413                 goto out;
 414
 415         /* If the autosuspend_delay time hasn't expired yet, reschedule. */
 416         if ((rpmflags & RPM_AUTO)
 417             && dev->power.runtime_status != RPM_SUSPENDING) {
 418                 unsigned long expires = pm_runtime_autosuspend_expiration(dev);
 419
 420                 if (expires != 0) {
 421                         /* Pending requests need to be canceled. */
 422                         dev->power.request = RPM_REQ_NONE;
 423
 424                         /*
 425                          * Optimization: If the timer is already running and is
 426                          * set to expire at or before the autosuspend delay,
 427                          * avoid the overhead of resetting it.  Just let it
 428                          * expire; pm_suspend_timer_fn() will take care of the
 429                          * rest.
 430                          */
 431                         if (!(dev->power.timer_expires && time_before_eq(
 432                             dev->power.timer_expires, expires))) {
 433                                 dev->power.timer_expires = expires;
 434                                 mod_timer(&dev->power.suspend_timer, expires);
 435                         }
 436                         dev->power.timer_autosuspends = 1;
 437                         goto out;
 438                 }
 439         }
 440
 441         /* Other scheduled or pending requests need to be canceled. */
 442         pm_runtime_cancel_pending(dev);
 443
 444         if (dev->power.runtime_status == RPM_SUSPENDING) {
 445                 DEFINE_WAIT(wait);
 446
 447                 if (rpmflags & (RPM_ASYNC | RPM_NOWAIT)) {
 448                         retval = -EINPROGRESS;
 449                         goto out;
 450                 }
 451
 452                 if (dev->power.irq_safe) {
 453                         spin_unlock(&dev->power.lock);
 454
 455                         cpu_relax();
 456
 457                         spin_lock(&dev->power.lock);
 458                         goto repeat;
 459                 }
 460
 461                 /* Wait for the other suspend running in parallel with us. */
 462                 for (;;) {
 463                         prepare_to_wait(&dev->power.wait_queue, &wait,
 464                                         TASK_UNINTERRUPTIBLE);
 465                         if (dev->power.runtime_status != RPM_SUSPENDING)
 466                                 break;
 467
 468                         spin_unlock_irq(&dev->power.lock);
 469
 470                         schedule();
 471
 472                         spin_lock_irq(&dev->power.lock);
 473                 }
 474                 finish_wait(&dev->power.wait_queue, &wait);
 475                 goto repeat;
 476         }
 477
 478         if (dev->power.no_callbacks)
 479                 goto no_callback;       /* Assume success. */
 480
 481         /* Carry out an asynchronous or a synchronous suspend. */
 482         if (rpmflags & RPM_ASYNC) {
 483                 dev->power.request = (rpmflags & RPM_AUTO) ?
 484                     RPM_REQ_AUTOSUSPEND : RPM_REQ_SUSPEND;
 485                 if (!dev->power.request_pending) {
 486                         dev->power.request_pending = true;
 487                         queue_work(pm_wq, &dev->power.work);
 488                 }
 489                 goto out;
 490         }
 491
 492         __update_runtime_status(dev, RPM_SUSPENDING);
 493
 494         if (dev->pm_domain)
 495                 callback = dev->pm_domain->ops.runtime_suspend;
 496         else if (dev->type && dev->type->pm)
 497                 callback = dev->type->pm->runtime_suspend;
 498         else if (dev->class && dev->class->pm)
 499                 callback = dev->class->pm->runtime_suspend;
 500         else if (dev->bus && dev->bus->pm)
 501                 callback = dev->bus->pm->runtime_suspend;
 502         else
 503                 callback = NULL;
 504
 505         if (!callback && dev->driver && dev->driver->pm)
 506                 callback = dev->driver->pm->runtime_suspend;
 507
 508         retval = rpm_callback(callback, dev);
 509         if (retval)
 510                 goto fail;
 511
 512  no_callback:
 513         __update_runtime_status(dev, RPM_SUSPENDED);
 514         pm_runtime_deactivate_timer(dev);
 515
 516         if (dev->parent) {
 517                 parent = dev->parent;
 518                 atomic_add_unless(&parent->power.child_count, -1, 0);
 519         }
 520         wake_up_all(&dev->power.wait_queue);
 521
 522         if (dev->power.deferred_resume) {
 523                 dev->power.deferred_resume = false;
 524                 rpm_resume(dev, 0);
 525                 retval = -EAGAIN;
 526                 goto out;
 527         }
 528
 529         /* Maybe the parent is now able to suspend. */
 530         if (parent && !parent->power.ignore_children && !dev->power.irq_safe) {
 531                 spin_unlock(&dev->power.lock);
 532
 533                 spin_lock(&parent->power.lock);
 534                 rpm_idle(parent, RPM_ASYNC);
 535                 spin_unlock(&parent->power.lock);
 536
 537                 spin_lock(&dev->power.lock);
 538         }
 539
 540  out:
 541         trace_rpm_return_int(dev, _THIS_IP_, retval);
 542
 543         return retval;
 544
 545  fail:
 546         __update_runtime_status(dev, RPM_ACTIVE);
 547         dev->power.deferred_resume = false;
 548         wake_up_all(&dev->power.wait_queue);
 549
 550         if (retval == -EAGAIN || retval == -EBUSY) {
 551                 dev->power.runtime_error = 0;
 552
 553                 /*
 554                  * If the callback routine failed an autosuspend, and
 555                  * if the last_busy time has been updated so that there
 556                  * is a new autosuspend expiration time, automatically
 557                  * reschedule another autosuspend.
 558                  */
 559                 if ((rpmflags & RPM_AUTO) &&
 560                     pm_runtime_autosuspend_expiration(dev) != 0)
 561                         goto repeat;
 562         } else {
 563                 pm_runtime_cancel_pending(dev);
 564         }
 565         goto out;
 566 }
 567
 568 /**
 569  * rpm_resume - Carry out runtime resume of given device.
 570  * @dev: Device to resume.
 571  * @rpmflags: Flag bits.
 572  *
 573  * Check if the device's runtime PM status allows it to be resumed.  Cancel
 574  * any scheduled or pending requests.  If another resume has been started
 575  * earlier, either return immediately or wait for it to finish, depending on the
 576  * RPM_NOWAIT and RPM_ASYNC flags.  Similarly, if there's a suspend running in
 577  * parallel with this function, either tell the other process to resume after
 578  * suspending (deferred_resume) or wait for it to finish.  If the RPM_ASYNC
 579  * flag is set then queue a resume request; otherwise run the
 580  * ->runtime_resume() callback directly.  Queue an idle notification for the
 581  * device if the resume succeeded.
 582  *
 583  * This function must be called under dev->power.lock with interrupts disabled.
 584  */
 585 static int rpm_resume(struct device *dev, int rpmflags)
 586         __releases(&dev->power.lock) __acquires(&dev->power.lock)
 587 {
 588         int (*callback)(struct device *);
 589         struct device *parent = NULL;
 590         int retval = 0;
 591
 592         trace_rpm_resume(dev, rpmflags);
 593
 594  repeat:
 595         if (dev->power.runtime_error)
 596                 retval = -EINVAL;
 597         else if (dev->power.disable_depth == 1 && dev->power.is_suspended
 598             && dev->power.runtime_status == RPM_ACTIVE)
 599                 retval = 1;
 600         else if (dev->power.disable_depth > 0)
 601                 retval = -EACCES;
 602         if (retval)
 603                 goto out;
 604
 605         /*
 606          * Other scheduled or pending requests need to be canceled.  Small
 607          * optimization: If an autosuspend timer is running, leave it running
 608          * rather than cancelling it now only to restart it again in the near
 609          * future.
 610          */
 611         dev->power.request = RPM_REQ_NONE;
 612         if (!dev->power.timer_autosuspends)
 613                 pm_runtime_deactivate_timer(dev);
 614
 615         if (dev->power.runtime_status == RPM_ACTIVE) {
 616                 retval = 1;
 617                 goto out;
 618         }
 619
 620         if (dev->power.runtime_status == RPM_RESUMING
 621             || dev->power.runtime_status == RPM_SUSPENDING) {
 622                 DEFINE_WAIT(wait);
 623
 624                 if (rpmflags & (RPM_ASYNC | RPM_NOWAIT)) {
 625                         if (dev->power.runtime_status == RPM_SUSPENDING)
 626                                 dev->power.deferred_resume = true;
 627                         else
 628                                 retval = -EINPROGRESS;
 629                         goto out;
 630                 }
 631
 632                 if (dev->power.irq_safe) {
 633                         spin_unlock(&dev->power.lock);
 634
 635                         cpu_relax();
 636
 637                         spin_lock(&dev->power.lock);
 638                         goto repeat;
 639                 }
 640
 641                 /* Wait for the operation carried out in parallel with us. */
 642                 for (;;) {
 643                         prepare_to_wait(&dev->power.wait_queue, &wait,
 644                                         TASK_UNINTERRUPTIBLE);
 645                         if (dev->power.runtime_status != RPM_RESUMING
 646                             && dev->power.runtime_status != RPM_SUSPENDING)
 647                                 break;
 648
 649                         spin_unlock_irq(&dev->power.lock);
 650
 651                         schedule();
 652
 653                         spin_lock_irq(&dev->power.lock);
 654                 }
 655                 finish_wait(&dev->power.wait_queue, &wait);
 656                 goto repeat;
 657         }
 658
 659         /*
 660          * See if we can skip waking up the parent.  This is safe only if
 661          * power.no_callbacks is set, because otherwise we don't know whether
 662          * the resume will actually succeed.
 663          */
 664         if (dev->power.no_callbacks && !parent && dev->parent) {
 665                 spin_lock_nested(&dev->parent->power.lock, SINGLE_DEPTH_NESTING);
 666                 if (dev->parent->power.disable_depth > 0
 667                     || dev->parent->power.ignore_children
 668                     || dev->parent->power.runtime_status == RPM_ACTIVE) {
 669                         atomic_inc(&dev->parent->power.child_count);
 670                         spin_unlock(&dev->parent->power.lock);
 671                         retval = 1;
 672                         goto no_callback;       /* Assume success. */
 673                 }
 674                 spin_unlock(&dev->parent->power.lock);
 675         }
 676
 677         /* Carry out an asynchronous or a synchronous resume. */
 678         if (rpmflags & RPM_ASYNC) {
 679                 dev->power.request = RPM_REQ_RESUME;
 680                 if (!dev->power.request_pending) {
 681                         dev->power.request_pending = true;
 682                         queue_work(pm_wq, &dev->power.work);
 683                 }
 684                 retval = 0;
 685                 goto out;
 686         }
 687
 688         if (!parent && dev->parent) {
 689                 /*
 690                  * Increment the parent's usage counter and resume it if
 691                  * necessary.  Not needed if dev is irq-safe; then the
 692                  * parent is permanently resumed.
 693                  */
 694                 parent = dev->parent;
 695                 if (dev->power.irq_safe)
 696                         goto skip_parent;
 697                 spin_unlock(&dev->power.lock);
 698
 699                 pm_runtime_get_noresume(parent);
 700
 701                 spin_lock(&parent->power.lock);
 702                 /*
 703                  * We can resume if the parent's runtime PM is disabled or it
 704                  * is set to ignore children.
 705                  */
 706                 if (!parent->power.disable_depth
 707                     && !parent->power.ignore_children) {
 708                         rpm_resume(parent, 0);
 709                         if (parent->power.runtime_status != RPM_ACTIVE)
 710                                 retval = -EBUSY;
 711                 }
 712                 spin_unlock(&parent->power.lock);
 713
 714                 spin_lock(&dev->power.lock);
 715                 if (retval)
 716                         goto out;
 717                 goto repeat;
 718         }
 719  skip_parent:
 720
 721         if (dev->power.no_callbacks)
 722                 goto no_callback;       /* Assume success. */
 723
 724         __update_runtime_status(dev, RPM_RESUMING);
 725
 726         if (dev->pm_domain)
 727                 callback = dev->pm_domain->ops.runtime_resume;
 728         else if (dev->type && dev->type->pm)
 729                 callback = dev->type->pm->runtime_resume;
 730         else if (dev->class && dev->class->pm)
 731                 callback = dev->class->pm->runtime_resume;
 732         else if (dev->bus && dev->bus->pm)
 733                 callback = dev->bus->pm->runtime_resume;
 734         else
 735                 callback = NULL;
 736
 737         if (!callback && dev->driver && dev->driver->pm)
 738                 callback = dev->driver->pm->runtime_resume;
 739
 740         retval = rpm_callback(callback, dev);
 741         if (retval) {
 742                 __update_runtime_status(dev, RPM_SUSPENDED);
 743                 pm_runtime_cancel_pending(dev);
 744         } else {
 745  no_callback:
 746                 __update_runtime_status(dev, RPM_ACTIVE);
 747                 if (parent)
 748                         atomic_inc(&parent->power.child_count);
 749         }
 750         wake_up_all(&dev->power.wait_queue);
 751
 752         if (retval >= 0)
 753                 rpm_idle(dev, RPM_ASYNC);
 754
 755  out:
 756         if (parent && !dev->power.irq_safe) {
 757                 spin_unlock_irq(&dev->power.lock);
 758
 759                 pm_runtime_put(parent);
 760
 761                 spin_lock_irq(&dev->power.lock);
 762         }
 763
 764         trace_rpm_return_int(dev, _THIS_IP_, retval);
 765
 766         return retval;
 767 }
 768
 769 /**
 770  * pm_runtime_work - Universal runtime PM work function.
 771  * @work: Work structure used for scheduling the execution of this function.
 772  *
 773  * Use @work to get the device object the work is to be done for, determine what
 774  * is to be done and execute the appropriate runtime PM function.
 775  */
 776 static void pm_runtime_work(struct work_struct *work)
 777 {
 778         struct device *dev = container_of(work, struct device, power.work);
 779         enum rpm_request req;
 780
 781         spin_lock_irq(&dev->power.lock);
 782
 783         if (!dev->power.request_pending)
 784                 goto out;
 785
 786         req = dev->power.request;
 787         dev->power.request = RPM_REQ_NONE;
 788         dev->power.request_pending = false;
 789
 790         switch (req) {
 791         case RPM_REQ_NONE:
 792                 break;
 793         case RPM_REQ_IDLE:
 794                 rpm_idle(dev, RPM_NOWAIT);
 795                 break;
 796         case RPM_REQ_SUSPEND:
 797                 rpm_suspend(dev, RPM_NOWAIT);
 798                 break;
 799         case RPM_REQ_AUTOSUSPEND:
 800                 rpm_suspend(dev, RPM_NOWAIT | RPM_AUTO);
 801                 break;
 802         case RPM_REQ_RESUME:
 803                 rpm_resume(dev, RPM_NOWAIT);
 804                 break;
 805         }
 806
 807  out:
 808         spin_unlock_irq(&dev->power.lock);
 809 }
 810
 811 /**
 812  * pm_suspend_timer_fn - Timer function for pm_schedule_suspend().
 813  * @data: Device pointer passed by pm_schedule_suspend().
 814  *
 815  * Check if the time is right and queue a suspend request.
 816  */
 817 static void pm_suspend_timer_fn(unsigned long data)
 818 {
 819         struct device *dev = (struct device *)data;
 820         unsigned long flags;
 821         unsigned long expires;
 822
 823         spin_lock_irqsave(&dev->power.lock, flags);
 824
 825         expires = dev->power.timer_expires;
 826         /* If 'expire' is after 'jiffies' we've been called too early. */
 827         if (expires > 0 && !time_after(expires, jiffies)) {
 828                 dev->power.timer_expires = 0;
 829                 rpm_suspend(dev, dev->power.timer_autosuspends ?
 830                     (RPM_ASYNC | RPM_AUTO) : RPM_ASYNC);
 831         }
 832
 833         spin_unlock_irqrestore(&dev->power.lock, flags);
 834 }
 835
 836 /**
 837  * pm_schedule_suspend - Set up a timer to submit a suspend request in future.
 838  * @dev: Device to suspend.
 839  * @delay: Time to wait before submitting a suspend request, in milliseconds.
 840  */
 841 int pm_schedule_suspend(struct device *dev, unsigned int delay)
 842 {
 843         unsigned long flags;
 844         int retval;
 845
 846         spin_lock_irqsave(&dev->power.lock, flags);
 847
 848         if (!delay) {
 849                 retval = rpm_suspend(dev, RPM_ASYNC);
 850                 goto out;
 851         }
 852
 853         retval = rpm_check_suspend_allowed(dev);
 854         if (retval)
 855                 goto out;
 856
 857         /* Other scheduled or pending requests need to be canceled. */
 858         pm_runtime_cancel_pending(dev);
 859
 860         dev->power.timer_expires = jiffies + msecs_to_jiffies(delay);
 861         dev->power.timer_expires += !dev->power.timer_expires;
 862         dev->power.timer_autosuspends = 0;
 863         mod_timer(&dev->power.suspend_timer, dev->power.timer_expires);
 864
 865  out:
 866         spin_unlock_irqrestore(&dev->power.lock, flags);
 867
 868         return retval;
 869 }
 870 EXPORT_SYMBOL_GPL(pm_schedule_suspend);
 871
 872 /**
 873  * __pm_runtime_idle - Entry point for runtime idle operations.
 874  * @dev: Device to send idle notification for.
 875  * @rpmflags: Flag bits.
 876  *
 877  * If the RPM_GET_PUT flag is set, decrement the device's usage count and
 878  * return immediately if it is larger than zero.  Then carry out an idle
 879  * notification, either synchronous or asynchronous.
 880  *
 881  * This routine may be called in atomic context if the RPM_ASYNC flag is set,
 882  * or if pm_runtime_irq_safe() has been called.
 883  */
 884 int __pm_runtime_idle(struct device *dev, int rpmflags)
 885 {
 886         unsigned long flags;
 887         int retval;
 888
 889         might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);
 890
 891         if (rpmflags & RPM_GET_PUT) {
 892                 if (!atomic_dec_and_test(&dev->power.usage_count))
 893                         return 0;
 894         }
 895
 896         spin_lock_irqsave(&dev->power.lock, flags);
 897         retval = rpm_idle(dev, rpmflags);
 898         spin_unlock_irqrestore(&dev->power.lock, flags);
 899
 900         return retval;
 901 }
 902 EXPORT_SYMBOL_GPL(__pm_runtime_idle);
 903
 904 /**
 905  * __pm_runtime_suspend - Entry point for runtime put/suspend operations.
 906  * @dev: Device to suspend.
 907  * @rpmflags: Flag bits.
 908  *
 909  * If the RPM_GET_PUT flag is set, decrement the device's usage count and
 910  * return immediately if it is larger than zero.  Then carry out a suspend,
 911  * either synchronous or asynchronous.
 912  *
 913  * This routine may be called in atomic context if the RPM_ASYNC flag is set,
 914  * or if pm_runtime_irq_safe() has been called.
 915  */
 916 int __pm_runtime_suspend(struct device *dev, int rpmflags)
 917 {
 918         unsigned long flags;
 919         int retval;
 920
 921         might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);
 922
 923         if (rpmflags & RPM_GET_PUT) {
 924                 if (!atomic_dec_and_test(&dev->power.usage_count))
 925                         return 0;
 926         }
 927
 928         spin_lock_irqsave(&dev->power.lock, flags);
 929         retval = rpm_suspend(dev, rpmflags);
 930         spin_unlock_irqrestore(&dev->power.lock, flags);
 931
 932         return retval;
 933 }
 934 EXPORT_SYMBOL_GPL(__pm_runtime_suspend);
 935
 936 /**
 937  * __pm_runtime_resume - Entry point for runtime resume operations.
 938  * @dev: Device to resume.
 939  * @rpmflags: Flag bits.
 940  *
 941  * If the RPM_GET_PUT flag is set, increment the device's usage count.  Then
 942  * carry out a resume, either synchronous or asynchronous.
 943  *
 944  * This routine may be called in atomic context if the RPM_ASYNC flag is set,
 945  * or if pm_runtime_irq_safe() has been called.
 946  */
 947 int __pm_runtime_resume(struct device *dev, int rpmflags)
 948 {
 949         unsigned long flags;
 950         int retval;
 951
 952         might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);
 953
 954         if (rpmflags & RPM_GET_PUT)
 955                 atomic_inc(&dev->power.usage_count);
 956
 957         spin_lock_irqsave(&dev->power.lock, flags);
 958         retval = rpm_resume(dev, rpmflags);
 959         spin_unlock_irqrestore(&dev->power.lock, flags);
 960
 961         return retval;
 962 }
 963 EXPORT_SYMBOL_GPL(__pm_runtime_resume);
 964
 965 /**
 966  * __pm_runtime_set_status - Set runtime PM status of a device.
 967  * @dev: Device to handle.
 968  * @status: New runtime PM status of the device.
 969  *
 970  * If runtime PM of the device is disabled or its power.runtime_error field is
 971  * different from zero, the status may be changed either to RPM_ACTIVE, or to
 972  * RPM_SUSPENDED, as long as that reflects the actual state of the device.
 973  * However, if the device has a parent and the parent is not active, and the
 974  * parent's power.ignore_children flag is unset, the device's status cannot be
 975  * set to RPM_ACTIVE, so -EBUSY is returned in that case.
 976  *
 977  * If successful, __pm_runtime_set_status() clears the power.runtime_error field
 978  * and the device parent's counter of unsuspended children is modified to
 979  * reflect the new status.  If the new status is RPM_SUSPENDED, an idle
 980  * notification request for the parent is submitted.
 981  */
 982 int __pm_runtime_set_status(struct device *dev, unsigned int status)
 983 {
 984         struct device *parent = dev->parent;
 985         unsigned long flags;
 986         bool notify_parent = false;
 987         int error = 0;
 988
 989         if (status != RPM_ACTIVE && status != RPM_SUSPENDED)
 990                 return -EINVAL;
 991
 992         spin_lock_irqsave(&dev->power.lock, flags);
 993
 994         if (!dev->power.runtime_error && !dev->power.disable_depth) {
 995                 error = -EAGAIN;
 996                 goto out;
 997         }
 998
 999         if (dev->power.runtime_status == status)
1000                 goto out_set;
1001
1002         if (status == RPM_SUSPENDED) {
1003                 /* It always is possible to set the status to 'suspended'. */
1004                 if (parent) {
1005                         atomic_add_unless(&parent->power.child_count, -1, 0);
1006                         notify_parent = !parent->power.ignore_children;
1007                 }
1008                 goto out_set;
1009         }
1010
1011         if (parent) {
1012                 spin_lock_nested(&parent->power.lock, SINGLE_DEPTH_NESTING);
1013
1014                 /*
1015                  * It is invalid to put an active child under a parent that is
1016                  * not active, has runtime PM enabled and the
1017                  * 'power.ignore_children' flag unset.
1018                  */
1019                 if (!parent->power.disable_depth
1020                     && !parent->power.ignore_children
1021                     && parent->power.runtime_status != RPM_ACTIVE)
1022                         error = -EBUSY;
1023                 else if (dev->power.runtime_status == RPM_SUSPENDED)
1024                         atomic_inc(&parent->power.child_count);
1025
1026                 spin_unlock(&parent->power.lock);
1027
1028                 if (error)
1029                         goto out;
1030         }
1031
1032  out_set:
1033         __update_runtime_status(dev, status);
1034         dev->power.runtime_error = 0;
1035  out:
1036         spin_unlock_irqrestore(&dev->power.lock, flags);
1037
1038         if (notify_parent)
1039                 pm_request_idle(parent);
1040
1041         return error;
1042 }
1043 EXPORT_SYMBOL_GPL(__pm_runtime_set_status);
1044
1045 /**
1046  * __pm_runtime_barrier - Cancel pending requests and wait for completions.
1047  * @dev: Device to handle.
1048  *
1049  * Flush all pending requests for the device from pm_wq and wait for all
1050  * runtime PM operations involving the device in progress to complete.
1051  *
1052  * Should be called under dev->power.lock with interrupts disabled.
1053  */
1054 static void __pm_runtime_barrier(struct device *dev)
1055 {
1056         pm_runtime_deactivate_timer(dev);
1057
1058         if (dev->power.request_pending) {
1059                 dev->power.request = RPM_REQ_NONE;
1060                 spin_unlock_irq(&dev->power.lock);
1061
1062                 cancel_work_sync(&dev->power.work);
1063
1064                 spin_lock_irq(&dev->power.lock);
1065                 dev->power.request_pending = false;
1066         }
1067
1068         if (dev->power.runtime_status == RPM_SUSPENDING
1069             || dev->power.runtime_status == RPM_RESUMING
1070             || dev->power.idle_notification) {
1071                 DEFINE_WAIT(wait);
1072
1073                 /* Suspend, wake-up or idle notification in progress. */
1074                 for (;;) {
1075                         prepare_to_wait(&dev->power.wait_queue, &wait,
1076                                         TASK_UNINTERRUPTIBLE);
1077                         if (dev->power.runtime_status != RPM_SUSPENDING
1078                             && dev->power.runtime_status != RPM_RESUMING
1079                             && !dev->power.idle_notification)
1080                                 break;
1081                         spin_unlock_irq(&dev->power.lock);
1082
1083                         schedule();
1084
1085                         spin_lock_irq(&dev->power.lock);
1086                 }
1087                 finish_wait(&dev->power.wait_queue, &wait);
1088         }
1089 }
1090
1091 /**
1092  * pm_runtime_barrier - Flush pending requests and wait for completions.
1093  * @dev: Device to handle.
1094  *
1095  * Prevent the device from being suspended by incrementing its usage counter and
1096  * if there's a pending resume request for the device, wake the device up.
1097  * Next, make sure that all pending requests for the device have been flushed
1098  * from pm_wq and wait for all runtime PM operations involving the device in
1099  * progress to complete.
1100  *
1101  * Return value:
1102  * 1, if there was a resume request pending and the device had to be woken up,
1103  * 0, otherwise
1104  */
1105 int pm_runtime_barrier(struct device *dev)
1106 {
1107         int retval = 0;
1108
1109         pm_runtime_get_noresume(dev);
1110         spin_lock_irq(&dev->power.lock);
1111
1112         if (dev->power.request_pending
1113             && dev->power.request == RPM_REQ_RESUME) {
1114                 rpm_resume(dev, 0);
1115                 retval = 1;
1116         }
1117
1118         __pm_runtime_barrier(dev);
1119
1120         spin_unlock_irq(&dev->power.lock);
1121         pm_runtime_put_noidle(dev);
1122
1123         return retval;
1124 }
1125 EXPORT_SYMBOL_GPL(pm_runtime_barrier);
1126
1127 /**
1128  * __pm_runtime_disable - Disable runtime PM of a device.
1129  * @dev: Device to handle.
1130  * @check_resume: If set, check if there's a resume request for the device.
1131  *
1132  * Increment power.disable_depth for the device and if was zero previously,
1133  * cancel all pending runtime PM requests for the device and wait for all
1134  * operations in progress to complete.  The device can be either active or
1135  * suspended after its runtime PM has been disabled.
1136  *
1137  * If @check_resume is set and there's a resume request pending when
1138  * __pm_runtime_disable() is called and power.disable_depth is zero, the
1139  * function will wake up the device before disabling its runtime PM.
1140  */
1141 void __pm_runtime_disable(struct device *dev, bool check_resume)
1142 {
1143         spin_lock_irq(&dev->power.lock);
1144
1145         if (dev->power.disable_depth > 0) {
1146                 dev->power.disable_depth++;
1147                 goto out;
1148         }
1149
1150         /*
1151          * Wake up the device if there's a resume request pending, because that
1152          * means there probably is some I/O to process and disabling runtime PM
1153          * shouldn't prevent the device from processing the I/O.
1154          */
1155         if (check_resume && dev->power.request_pending
1156             && dev->power.request == RPM_REQ_RESUME) {
1157                 /*
1158                  * Prevent suspends and idle notifications from being carried
1159                  * out after we have woken up the device.
1160                  */
1161                 pm_runtime_get_noresume(dev);
1162
1163                 rpm_resume(dev, 0);
1164
1165                 pm_runtime_put_noidle(dev);
1166         }
1167
1168         if (!dev->power.disable_depth++)
1169                 __pm_runtime_barrier(dev);
1170
1171  out:
1172         spin_unlock_irq(&dev->power.lock);
1173 }
1174 EXPORT_SYMBOL_GPL(__pm_runtime_disable);
1175
1176 /**
1177  * pm_runtime_enable - Enable runtime PM of a device.
1178  * @dev: Device to handle.
1179  */
1180 void pm_runtime_enable(struct device *dev)
1181 {
1182         unsigned long flags;
1183
1184         spin_lock_irqsave(&dev->power.lock, flags);
1185
1186         if (dev->power.disable_depth > 0)
1187                 dev->power.disable_depth--;
1188         else
1189                 dev_warn(dev, "Unbalanced %s!\n", __func__);
1190
1191         spin_unlock_irqrestore(&dev->power.lock, flags);
1192 }
1193 EXPORT_SYMBOL_GPL(pm_runtime_enable);
1194
1195 /**
1196  * pm_runtime_forbid - Block runtime PM of a device.
1197  * @dev: Device to handle.
1198  *
1199  * Increase the device's usage count and clear its power.runtime_auto flag,
1200  * so that it cannot be suspended at run time until pm_runtime_allow() is called
1201  * for it.
1202  */
1203 void pm_runtime_forbid(struct device *dev)
1204 {
1205         spin_lock_irq(&dev->power.lock);
1206         if (!dev->power.runtime_auto)
1207                 goto out;
1208
1209         dev->power.runtime_auto = false;
1210         atomic_inc(&dev->power.usage_count);
1211         rpm_resume(dev, 0);
1212
1213  out:
1214         spin_unlock_irq(&dev->power.lock);
1215 }
1216 EXPORT_SYMBOL_GPL(pm_runtime_forbid);
1217
1218 /**
1219  * pm_runtime_allow - Unblock runtime PM of a device.
1220  * @dev: Device to handle.
1221  *
1222  * Decrease the device's usage count and set its power.runtime_auto flag.
1223  */
1224 void pm_runtime_allow(struct device *dev)
1225 {
1226         spin_lock_irq(&dev->power.lock);
1227         if (dev->power.runtime_auto)
1228                 goto out;
1229
1230         dev->power.runtime_auto = true;
1231         if (atomic_dec_and_test(&dev->power.usage_count))
1232                 rpm_idle(dev, RPM_AUTO);
1233
1234  out:
1235         spin_unlock_irq(&dev->power.lock);
1236 }
1237 EXPORT_SYMBOL_GPL(pm_runtime_allow);
1238
1239 /**
1240  * pm_runtime_no_callbacks - Ignore runtime PM callbacks for a device.
1241  * @dev: Device to handle.
1242  *
1243  * Set the power.no_callbacks flag, which tells the PM core that this
1244  * device is power-managed through its parent and has no runtime PM
1245  * callbacks of its own.  The runtime sysfs attributes will be removed.
1246  */
1247 void pm_runtime_no_callbacks(struct device *dev)
1248 {
1249         spin_lock_irq(&dev->power.lock);
1250         dev->power.no_callbacks = 1;
1251         spin_unlock_irq(&dev->power.lock);
1252         if (device_is_registered(dev))
1253                 rpm_sysfs_remove(dev);
1254 }
1255 EXPORT_SYMBOL_GPL(pm_runtime_no_callbacks);
1256
1257 /**
1258  * pm_runtime_irq_safe - Leave interrupts disabled during callbacks.
1259  * @dev: Device to handle
1260  *
1261  * Set the power.irq_safe flag, which tells the PM core that the
1262  * ->runtime_suspend() and ->runtime_resume() callbacks for this device should
1263  * always be invoked with the spinlock held and interrupts disabled.  It also
1264  * causes the parent's usage counter to be permanently incremented, preventing
1265  * the parent from runtime suspending -- otherwise an irq-safe child might have
1266  * to wait for a non-irq-safe parent.
1267  */
1268 void pm_runtime_irq_safe(struct device *dev)
1269 {
1270         if (dev->parent)
1271                 pm_runtime_get_sync(dev->parent);
1272         spin_lock_irq(&dev->power.lock);
1273         dev->power.irq_safe = 1;
1274         spin_unlock_irq(&dev->power.lock);
1275 }
1276 EXPORT_SYMBOL_GPL(pm_runtime_irq_safe);
1277
1278 /**
1279  * update_autosuspend - Handle a change to a device's autosuspend settings.
1280  * @dev: Device to handle.
1281  * @old_delay: The former autosuspend_delay value.
1282  * @old_use: The former use_autosuspend value.
1283  *
1284  * Prevent runtime suspend if the new delay is negative and use_autosuspend is
1285  * set; otherwise allow it.  Send an idle notification if suspends are allowed.
1286  *
1287  * This function must be called under dev->power.lock with interrupts disabled.
1288  */
1289 static void update_autosuspend(struct device *dev, int old_delay, int old_use)
1290 {
1291         int delay = dev->power.autosuspend_delay;
1292
1293         /* Should runtime suspend be prevented now? */
1294         if (dev->power.use_autosuspend && delay < 0) {
1295
1296                 /* If it used to be allowed then prevent it. */
1297                 if (!old_use || old_delay >= 0) {
1298                         atomic_inc(&dev->power.usage_count);
1299                         rpm_resume(dev, 0);
1300                 }
1301         }
1302
1303         /* Runtime suspend should be allowed now. */
1304         else {
1305
1306                 /* If it used to be prevented then allow it. */
1307                 if (old_use && old_delay < 0)
1308                         atomic_dec(&dev->power.usage_count);
1309
1310                 /* Maybe we can autosuspend now. */
1311                 rpm_idle(dev, RPM_AUTO);
1312         }
1313 }
1314
1315 /**
1316  * pm_runtime_set_autosuspend_delay - Set a device's autosuspend_delay value.
1317  * @dev: Device to handle.
1318  * @delay: Value of the new delay in milliseconds.
1319  *
1320  * Set the device's power.autosuspend_delay value.  If it changes to negative
1321  * and the power.use_autosuspend flag is set, prevent runtime suspends.  If it
1322  * changes the other way, allow runtime suspends.
1323  */
1324 void pm_runtime_set_autosuspend_delay(struct device *dev, int delay)
1325 {
1326         int old_delay, old_use;
1327
1328         spin_lock_irq(&dev->power.lock);
1329         old_delay = dev->power.autosuspend_delay;
1330         old_use = dev->power.use_autosuspend;
1331         dev->power.autosuspend_delay = delay;
1332         update_autosuspend(dev, old_delay, old_use);
1333         spin_unlock_irq(&dev->power.lock);
1334 }
1335 EXPORT_SYMBOL_GPL(pm_runtime_set_autosuspend_delay);
1336
1337 /**
1338  * __pm_runtime_use_autosuspend - Set a device's use_autosuspend flag.
1339  * @dev: Device to handle.
1340  * @use: New value for use_autosuspend.
1341  *
1342  * Set the device's power.use_autosuspend flag, and allow or prevent runtime
1343  * suspends as needed.
1344  */
1345 void __pm_runtime_use_autosuspend(struct device *dev, bool use)
1346 {
1347         int old_delay, old_use;
1348
1349         spin_lock_irq(&dev->power.lock);
1350         old_delay = dev->power.autosuspend_delay;
1351         old_use = dev->power.use_autosuspend;
1352         dev->power.use_autosuspend = use;
1353         update_autosuspend(dev, old_delay, old_use);
1354         spin_unlock_irq(&dev->power.lock);
1355 }
1356 EXPORT_SYMBOL_GPL(__pm_runtime_use_autosuspend);
1357
1358 /**
1359  * pm_runtime_init - Initialize runtime PM fields in given device object.
1360  * @dev: Device object to initialize.
1361  */
1362 void pm_runtime_init(struct device *dev)
1363 {
1364         dev->power.runtime_status = RPM_SUSPENDED;
1365         dev->power.idle_notification = false;
1366
1367         dev->power.disable_depth = 1;
1368         atomic_set(&dev->power.usage_count, 0);
1369
1370         dev->power.runtime_error = 0;
1371
1372         atomic_set(&dev->power.child_count, 0);
1373         pm_suspend_ignore_children(dev, false);
1374         dev->power.runtime_auto = true;
1375
1376         dev->power.request_pending = false;
1377         dev->power.request = RPM_REQ_NONE;
1378         dev->power.deferred_resume = false;
1379         dev->power.accounting_timestamp = jiffies;
1380         INIT_WORK(&dev->power.work, pm_runtime_work);
1381
1382         dev->power.timer_expires = 0;
1383         setup_timer(&dev->power.suspend_timer, pm_suspend_timer_fn,
1384                         (unsigned long)dev);
1385
1386         init_waitqueue_head(&dev->power.wait_queue);
1387 }
1388
1389 /**
1390  * pm_runtime_remove - Prepare for removing a device from device hierarchy.
1391  * @dev: Device object being removed from device hierarchy.
1392  */
1393 void pm_runtime_remove(struct device *dev)
1394 {
1395         __pm_runtime_disable(dev, false);
1396
1397         /* Change the status back to 'suspended' to match the initial status. */
1398         if (dev->power.runtime_status == RPM_ACTIVE)
1399                 pm_runtime_set_suspended(dev);
1400         if (dev->power.irq_safe && dev->parent)
1401                 pm_runtime_put(dev->parent);
1402 }