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 typedef int (*pm_callback_t)(struct device *);
  17
  18 static pm_callback_t __rpm_get_callback(struct device *dev, size_t cb_offset)
  19 {
  20         pm_callback_t cb;
  21         const struct dev_pm_ops *ops;
  22
  23         if (dev->pm_domain)
  24                 ops = &dev->pm_domain->ops;
  25         else if (dev->type && dev->type->pm)
  26                 ops = dev->type->pm;
  27         else if (dev->class && dev->class->pm)
  28                 ops = dev->class->pm;
  29         else if (dev->bus && dev->bus->pm)
  30                 ops = dev->bus->pm;
  31         else
  32                 ops = NULL;
  33
  34         if (ops)
  35                 cb = *(pm_callback_t *)((void *)ops + cb_offset);
  36         else
  37                 cb = NULL;
  38
  39         if (!cb && dev->driver && dev->driver->pm)
  40                 cb = *(pm_callback_t *)((void *)dev->driver->pm + cb_offset);
  41
  42         return cb;
  43 }
  44
  45 #define RPM_GET_CALLBACK(dev, callback) \
  46                 __rpm_get_callback(dev, offsetof(struct dev_pm_ops, callback))
  47
  48 static int rpm_resume(struct device *dev, int rpmflags);
  49 static int rpm_suspend(struct device *dev, int rpmflags);
  50
  51 /**
  52  * update_pm_runtime_accounting - Update the time accounting of power states
  53  * @dev: Device to update the accounting for
  54  *
  55  * In order to be able to have time accounting of the various power states
  56  * (as used by programs such as PowerTOP to show the effectiveness of runtime
  57  * PM), we need to track the time spent in each state.
  58  * update_pm_runtime_accounting must be called each time before the
  59  * runtime_status field is updated, to account the time in the old state
  60  * correctly.
  61  */
  62 void update_pm_runtime_accounting(struct device *dev)
  63 {
  64         unsigned long now = jiffies;
  65         unsigned long delta;
  66
  67         delta = now - dev->power.accounting_timestamp;
  68
  69         dev->power.accounting_timestamp = now;
  70
  71         if (dev->power.disable_depth > 0)
  72                 return;
  73
  74         if (dev->power.runtime_status == RPM_SUSPENDED)
  75                 dev->power.suspended_jiffies += delta;
  76         else
  77                 dev->power.active_jiffies += delta;
  78 }
  79
  80 static void __update_runtime_status(struct device *dev, enum rpm_status status)
  81 {
  82         update_pm_runtime_accounting(dev);
  83         dev->power.runtime_status = status;
  84 }
  85
  86 /**
  87  * pm_runtime_deactivate_timer - Deactivate given device's suspend timer.
  88  * @dev: Device to handle.
  89  */
  90 static void pm_runtime_deactivate_timer(struct device *dev)
  91 {
  92         if (dev->power.timer_expires > 0) {
  93                 del_timer(&dev->power.suspend_timer);
  94                 dev->power.timer_expires = 0;
  95         }
  96 }
  97
  98 /**
  99  * pm_runtime_cancel_pending - Deactivate suspend timer and cancel requests.
 100  * @dev: Device to handle.
 101  */
 102 static void pm_runtime_cancel_pending(struct device *dev)
 103 {
 104         pm_runtime_deactivate_timer(dev);
 105         /*
 106          * In case there's a request pending, make sure its work function will
 107          * return without doing anything.
 108          */
 109         dev->power.request = RPM_REQ_NONE;
 110 }
 111
 112 /*
 113  * pm_runtime_autosuspend_expiration - Get a device's autosuspend-delay expiration time.
 114  * @dev: Device to handle.
 115  *
 116  * Compute the autosuspend-delay expiration time based on the device's
 117  * power.last_busy time.  If the delay has already expired or is disabled
 118  * (negative) or the power.use_autosuspend flag isn't set, return 0.
 119  * Otherwise return the expiration time in jiffies (adjusted to be nonzero).
 120  *
 121  * This function may be called either with or without dev->power.lock held.
 122  * Either way it can be racy, since power.last_busy may be updated at any time.
 123  */
 124 unsigned long pm_runtime_autosuspend_expiration(struct device *dev)
 125 {
 126         int autosuspend_delay;
 127         long elapsed;
 128         unsigned long last_busy;
 129         unsigned long expires = 0;
 130
 131         if (!dev->power.use_autosuspend)
 132                 goto out;
 133
 134         autosuspend_delay = ACCESS_ONCE(dev->power.autosuspend_delay);
 135         if (autosuspend_delay < 0)
 136                 goto out;
 137
 138         last_busy = ACCESS_ONCE(dev->power.last_busy);
 139         elapsed = jiffies - last_busy;
 140         if (elapsed < 0)
 141                 goto out;       /* jiffies has wrapped around. */
 142
 143         /*
 144          * If the autosuspend_delay is >= 1 second, align the timer by rounding
 145          * up to the nearest second.
 146          */
 147         expires = last_busy + msecs_to_jiffies(autosuspend_delay);
 148         if (autosuspend_delay >= 1000)
 149                 expires = round_jiffies(expires);
 150         expires += !expires;
 151         if (elapsed >= expires - last_busy)
 152                 expires = 0;    /* Already expired. */
 153
 154  out:
 155         return expires;
 156 }
 157 EXPORT_SYMBOL_GPL(pm_runtime_autosuspend_expiration);
 158
 159 static int dev_memalloc_noio(struct device *dev, void *data)
 160 {
 161         return dev->power.memalloc_noio;
 162 }
 163
 164 /*
 165  * pm_runtime_set_memalloc_noio - Set a device's memalloc_noio flag.
 166  * @dev: Device to handle.
 167  * @enable: True for setting the flag and False for clearing the flag.
 168  *
 169  * Set the flag for all devices in the path from the device to the
 170  * root device in the device tree if @enable is true, otherwise clear
 171  * the flag for devices in the path whose siblings don't set the flag.
 172  *
 173  * The function should only be called by block device, or network
 174  * device driver for solving the deadlock problem during runtime
 175  * resume/suspend:
 176  *
 177  *     If memory allocation with GFP_KERNEL is called inside runtime
 178  *     resume/suspend callback of any one of its ancestors(or the
 179  *     block device itself), the deadlock may be triggered inside the
 180  *     memory allocation since it might not complete until the block
 181  *     device becomes active and the involed page I/O finishes. The
 182  *     situation is pointed out first by Alan Stern. Network device
 183  *     are involved in iSCSI kind of situation.
 184  *
 185  * The lock of dev_hotplug_mutex is held in the function for handling
 186  * hotplug race because pm_runtime_set_memalloc_noio() may be called
 187  * in async probe().
 188  *
 189  * The function should be called between device_add() and device_del()
 190  * on the affected device(block/network device).
 191  */
 192 void pm_runtime_set_memalloc_noio(struct device *dev, bool enable)
 193 {
 194         static DEFINE_MUTEX(dev_hotplug_mutex);
 195
 196         mutex_lock(&dev_hotplug_mutex);
 197         for (;;) {
 198                 bool enabled;
 199
 200                 /* hold power lock since bitfield is not SMP-safe. */
 201                 spin_lock_irq(&dev->power.lock);
 202                 enabled = dev->power.memalloc_noio;
 203                 dev->power.memalloc_noio = enable;
 204                 spin_unlock_irq(&dev->power.lock);
 205
 206                 /*
 207                  * not need to enable ancestors any more if the device
 208                  * has been enabled.
 209                  */
 210                 if (enabled && enable)
 211                         break;
 212
 213                 dev = dev->parent;
 214
 215                 /*
 216                  * clear flag of the parent device only if all the
 217                  * children don't set the flag because ancestor's
 218                  * flag was set by any one of the descendants.
 219                  */
 220                 if (!dev || (!enable &&
 221                              device_for_each_child(dev, NULL,
 222                                                    dev_memalloc_noio)))
 223                         break;
 224         }
 225         mutex_unlock(&dev_hotplug_mutex);
 226 }
 227 EXPORT_SYMBOL_GPL(pm_runtime_set_memalloc_noio);
 228
 229 /**
 230  * rpm_check_suspend_allowed - Test whether a device may be suspended.
 231  * @dev: Device to test.
 232  */
 233 static int rpm_check_suspend_allowed(struct device *dev)
 234 {
 235         int retval = 0;
 236
 237         if (dev->power.runtime_error)
 238                 retval = -EINVAL;
 239         else if (dev->power.disable_depth > 0)
 240                 retval = -EACCES;
 241         else if (atomic_read(&dev->power.usage_count) > 0)
 242                 retval = -EAGAIN;
 243         else if (!pm_children_suspended(dev))
 244                 retval = -EBUSY;
 245
 246         /* Pending resume requests take precedence over suspends. */
 247         else if ((dev->power.deferred_resume
 248                         && dev->power.runtime_status == RPM_SUSPENDING)
 249             || (dev->power.request_pending
 250                         && dev->power.request == RPM_REQ_RESUME))
 251                 retval = -EAGAIN;
 252         else if (__dev_pm_qos_read_value(dev) < 0)
 253                 retval = -EPERM;
 254         else if (dev->power.runtime_status == RPM_SUSPENDED)
 255                 retval = 1;
 256
 257         return retval;
 258 }
 259
 260 /**
 261  * __rpm_callback - Run a given runtime PM callback for a given device.
 262  * @cb: Runtime PM callback to run.
 263  * @dev: Device to run the callback for.
 264  */
 265 static int __rpm_callback(int (*cb)(struct device *), struct device *dev)
 266         __releases(&dev->power.lock) __acquires(&dev->power.lock)
 267 {
 268         int retval;
 269
 270         if (dev->power.irq_safe)
 271                 spin_unlock(&dev->power.lock);
 272         else
 273                 spin_unlock_irq(&dev->power.lock);
 274
 275         retval = cb(dev);
 276
 277         if (dev->power.irq_safe)
 278                 spin_lock(&dev->power.lock);
 279         else
 280                 spin_lock_irq(&dev->power.lock);
 281
 282         return retval;
 283 }
 284
 285 /**
 286  * rpm_idle - Notify device bus type if the device can be suspended.
 287  * @dev: Device to notify the bus type about.
 288  * @rpmflags: Flag bits.
 289  *
 290  * Check if the device's runtime PM status allows it to be suspended.  If
 291  * another idle notification has been started earlier, return immediately.  If
 292  * the RPM_ASYNC flag is set then queue an idle-notification request; otherwise
 293  * run the ->runtime_idle() callback directly. If the ->runtime_idle callback
 294  * doesn't exist or if it returns 0, call rpm_suspend with the RPM_AUTO flag.
 295  *
 296  * This function must be called under dev->power.lock with interrupts disabled.
 297  */
 298 static int rpm_idle(struct device *dev, int rpmflags)
 299 {
 300         int (*callback)(struct device *);
 301         int retval;
 302
 303         trace_rpm_idle(dev, rpmflags);
 304         retval = rpm_check_suspend_allowed(dev);
 305         if (retval < 0)
 306                 ;       /* Conditions are wrong. */
 307
 308         /* Idle notifications are allowed only in the RPM_ACTIVE state. */
 309         else if (dev->power.runtime_status != RPM_ACTIVE)
 310                 retval = -EAGAIN;
 311
 312         /*
 313          * Any pending request other than an idle notification takes
 314          * precedence over us, except that the timer may be running.
 315          */
 316         else if (dev->power.request_pending &&
 317             dev->power.request > RPM_REQ_IDLE)
 318                 retval = -EAGAIN;
 319
 320         /* Act as though RPM_NOWAIT is always set. */
 321         else if (dev->power.idle_notification)
 322                 retval = -EINPROGRESS;
 323         if (retval)
 324                 goto out;
 325
 326         /* Pending requests need to be canceled. */
 327         dev->power.request = RPM_REQ_NONE;
 328
 329         if (dev->power.no_callbacks)
 330                 goto out;
 331
 332         /* Carry out an asynchronous or a synchronous idle notification. */
 333         if (rpmflags & RPM_ASYNC) {
 334                 dev->power.request = RPM_REQ_IDLE;
 335                 if (!dev->power.request_pending) {
 336                         dev->power.request_pending = true;
 337                         queue_work(pm_wq, &dev->power.work);
 338                 }
 339                 trace_rpm_return_int(dev, _THIS_IP_, 0);
 340                 return 0;
 341         }
 342
 343         dev->power.idle_notification = true;
 344
 345         callback = RPM_GET_CALLBACK(dev, runtime_idle);
 346
 347         if (callback)
 348                 retval = __rpm_callback(callback, dev);
 349
 350         dev->power.idle_notification = false;
 351         wake_up_all(&dev->power.wait_queue);
 352
 353  out:
 354         trace_rpm_return_int(dev, _THIS_IP_, retval);
 355         return retval ? retval : rpm_suspend(dev, rpmflags | RPM_AUTO);
 356 }
 357
 358 /**
 359  * rpm_callback - Run a given runtime PM callback for a given device.
 360  * @cb: Runtime PM callback to run.
 361  * @dev: Device to run the callback for.
 362  */
 363 static int rpm_callback(int (*cb)(struct device *), struct device *dev)
 364 {
 365         int retval;
 366
 367         if (!cb)
 368                 return -ENOSYS;
 369
 370         if (dev->power.memalloc_noio) {
 371                 unsigned int noio_flag;
 372
 373                 /*
 374                  * Deadlock might be caused if memory allocation with
 375                  * GFP_KERNEL happens inside runtime_suspend and
 376                  * runtime_resume callbacks of one block device's
 377                  * ancestor or the block device itself. Network
 378                  * device might be thought as part of iSCSI block
 379                  * device, so network device and its ancestor should
 380                  * be marked as memalloc_noio too.
 381                  */
 382                 noio_flag = memalloc_noio_save();
 383                 retval = __rpm_callback(cb, dev);
 384                 memalloc_noio_restore(noio_flag);
 385         } else {
 386                 retval = __rpm_callback(cb, dev);
 387         }
 388
 389         dev->power.runtime_error = retval;
 390         return retval != -EACCES ? retval : -EIO;
 391 }
 392
 393 /**
 394  * rpm_suspend - Carry out runtime suspend of given device.
 395  * @dev: Device to suspend.
 396  * @rpmflags: Flag bits.
 397  *
 398  * Check if the device's runtime PM status allows it to be suspended.
 399  * Cancel a pending idle notification, autosuspend or suspend. If
 400  * another suspend has been started earlier, either return immediately
 401  * or wait for it to finish, depending on the RPM_NOWAIT and RPM_ASYNC
 402  * flags. If the RPM_ASYNC flag is set then queue a suspend request;
 403  * otherwise run the ->runtime_suspend() callback directly. When
 404  * ->runtime_suspend succeeded, if a deferred resume was requested while
 405  * the callback was running then carry it out, otherwise send an idle
 406  * notification for its parent (if the suspend succeeded and both
 407  * ignore_children of parent->power and irq_safe of dev->power are not set).
 408  * If ->runtime_suspend failed with -EAGAIN or -EBUSY, and if the RPM_AUTO
 409  * flag is set and the next autosuspend-delay expiration time is in the
 410  * future, schedule another autosuspend attempt.
 411  *
 412  * This function must be called under dev->power.lock with interrupts disabled.
 413  */
 414 static int rpm_suspend(struct device *dev, int rpmflags)
 415         __releases(&dev->power.lock) __acquires(&dev->power.lock)
 416 {
 417         int (*callback)(struct device *);
 418         struct device *parent = NULL;
 419         int retval;
 420
 421         trace_rpm_suspend(dev, rpmflags);
 422
 423  repeat:
 424         retval = rpm_check_suspend_allowed(dev);
 425
 426         if (retval < 0)
 427                 ;       /* Conditions are wrong. */
 428
 429         /* Synchronous suspends are not allowed in the RPM_RESUMING state. */
 430         else if (dev->power.runtime_status == RPM_RESUMING &&
 431             !(rpmflags & RPM_ASYNC))
 432                 retval = -EAGAIN;
 433         if (retval)
 434                 goto out;
 435
 436         /* If the autosuspend_delay time hasn't expired yet, reschedule. */
 437         if ((rpmflags & RPM_AUTO)
 438             && dev->power.runtime_status != RPM_SUSPENDING) {
 439                 unsigned long expires = pm_runtime_autosuspend_expiration(dev);
 440
 441                 if (expires != 0) {
 442                         /* Pending requests need to be canceled. */
 443                         dev->power.request = RPM_REQ_NONE;
 444
 445                         /*
 446                          * Optimization: If the timer is already running and is
 447                          * set to expire at or before the autosuspend delay,
 448                          * avoid the overhead of resetting it.  Just let it
 449                          * expire; pm_suspend_timer_fn() will take care of the
 450                          * rest.
 451                          */
 452                         if (!(dev->power.timer_expires && time_before_eq(
 453                             dev->power.timer_expires, expires))) {
 454                                 dev->power.timer_expires = expires;
 455                                 mod_timer(&dev->power.suspend_timer, expires);
 456                         }
 457                         dev->power.timer_autosuspends = 1;
 458                         goto out;
 459                 }
 460         }
 461
 462         /* Other scheduled or pending requests need to be canceled. */
 463         pm_runtime_cancel_pending(dev);
 464
 465         if (dev->power.runtime_status == RPM_SUSPENDING) {
 466                 DEFINE_WAIT(wait);
 467
 468                 if (rpmflags & (RPM_ASYNC | RPM_NOWAIT)) {
 469                         retval = -EINPROGRESS;
 470                         goto out;
 471                 }
 472
 473                 if (dev->power.irq_safe) {
 474                         spin_unlock(&dev->power.lock);
 475
 476                         cpu_relax();
 477
 478                         spin_lock(&dev->power.lock);
 479                         goto repeat;
 480                 }
 481
 482                 /* Wait for the other suspend running in parallel with us. */
 483                 for (;;) {
 484                         prepare_to_wait(&dev->power.wait_queue, &wait,
 485                                         TASK_UNINTERRUPTIBLE);
 486                         if (dev->power.runtime_status != RPM_SUSPENDING)
 487                                 break;
 488
 489                         spin_unlock_irq(&dev->power.lock);
 490
 491                         schedule();
 492
 493                         spin_lock_irq(&dev->power.lock);
 494                 }
 495                 finish_wait(&dev->power.wait_queue, &wait);
 496                 goto repeat;
 497         }
 498
 499         if (dev->power.no_callbacks)
 500                 goto no_callback;       /* Assume success. */
 501
 502         /* Carry out an asynchronous or a synchronous suspend. */
 503         if (rpmflags & RPM_ASYNC) {
 504                 dev->power.request = (rpmflags & RPM_AUTO) ?
 505                     RPM_REQ_AUTOSUSPEND : RPM_REQ_SUSPEND;
 506                 if (!dev->power.request_pending) {
 507                         dev->power.request_pending = true;
 508                         queue_work(pm_wq, &dev->power.work);
 509                 }
 510                 goto out;
 511         }
 512
 513         __update_runtime_status(dev, RPM_SUSPENDING);
 514
 515         callback = RPM_GET_CALLBACK(dev, runtime_suspend);
 516
 517         retval = rpm_callback(callback, dev);
 518         if (retval)
 519                 goto fail;
 520
 521  no_callback:
 522         __update_runtime_status(dev, RPM_SUSPENDED);
 523         pm_runtime_deactivate_timer(dev);
 524
 525         if (dev->parent) {
 526                 parent = dev->parent;
 527                 atomic_add_unless(&parent->power.child_count, -1, 0);
 528         }
 529         wake_up_all(&dev->power.wait_queue);
 530
 531         if (dev->power.deferred_resume) {
 532                 dev->power.deferred_resume = false;
 533                 rpm_resume(dev, 0);
 534                 retval = -EAGAIN;
 535                 goto out;
 536         }
 537
 538         /* Maybe the parent is now able to suspend. */
 539         if (parent && !parent->power.ignore_children && !dev->power.irq_safe) {
 540                 spin_unlock(&dev->power.lock);
 541
 542                 spin_lock(&parent->power.lock);
 543                 rpm_idle(parent, RPM_ASYNC);
 544                 spin_unlock(&parent->power.lock);
 545
 546                 spin_lock(&dev->power.lock);
 547         }
 548
 549  out:
 550         trace_rpm_return_int(dev, _THIS_IP_, retval);
 551
 552         return retval;
 553
 554  fail:
 555         __update_runtime_status(dev, RPM_ACTIVE);
 556         dev->power.deferred_resume = false;
 557         wake_up_all(&dev->power.wait_queue);
 558
 559         if (retval == -EAGAIN || retval == -EBUSY) {
 560                 dev->power.runtime_error = 0;
 561
 562                 /*
 563                  * If the callback routine failed an autosuspend, and
 564                  * if the last_busy time has been updated so that there
 565                  * is a new autosuspend expiration time, automatically
 566                  * reschedule another autosuspend.
 567                  */
 568                 if ((rpmflags & RPM_AUTO) &&
 569                     pm_runtime_autosuspend_expiration(dev) != 0)
 570                         goto repeat;
 571         } else {
 572                 pm_runtime_cancel_pending(dev);
 573         }
 574         goto out;
 575 }
 576
 577 /**
 578  * rpm_resume - Carry out runtime resume of given device.
 579  * @dev: Device to resume.
 580  * @rpmflags: Flag bits.
 581  *
 582  * Check if the device's runtime PM status allows it to be resumed.  Cancel
 583  * any scheduled or pending requests.  If another resume has been started
 584  * earlier, either return immediately or wait for it to finish, depending on the
 585  * RPM_NOWAIT and RPM_ASYNC flags.  Similarly, if there's a suspend running in
 586  * parallel with this function, either tell the other process to resume after
 587  * suspending (deferred_resume) or wait for it to finish.  If the RPM_ASYNC
 588  * flag is set then queue a resume request; otherwise run the
 589  * ->runtime_resume() callback directly.  Queue an idle notification for the
 590  * device if the resume succeeded.
 591  *
 592  * This function must be called under dev->power.lock with interrupts disabled.
 593  */
 594 static int rpm_resume(struct device *dev, int rpmflags)
 595         __releases(&dev->power.lock) __acquires(&dev->power.lock)
 596 {
 597         int (*callback)(struct device *);
 598         struct device *parent = NULL;
 599         int retval = 0;
 600
 601         trace_rpm_resume(dev, rpmflags);
 602
 603  repeat:
 604         if (dev->power.runtime_error)
 605                 retval = -EINVAL;
 606         else if (dev->power.disable_depth == 1 && dev->power.is_suspended
 607             && dev->power.runtime_status == RPM_ACTIVE)
 608                 retval = 1;
 609         else if (dev->power.disable_depth > 0)
 610                 retval = -EACCES;
 611         if (retval)
 612                 goto out;
 613
 614         /*
 615          * Other scheduled or pending requests need to be canceled.  Small
 616          * optimization: If an autosuspend timer is running, leave it running
 617          * rather than cancelling it now only to restart it again in the near
 618          * future.
 619          */
 620         dev->power.request = RPM_REQ_NONE;
 621         if (!dev->power.timer_autosuspends)
 622                 pm_runtime_deactivate_timer(dev);
 623
 624         if (dev->power.runtime_status == RPM_ACTIVE) {
 625                 retval = 1;
 626                 goto out;
 627         }
 628
 629         if (dev->power.runtime_status == RPM_RESUMING
 630             || dev->power.runtime_status == RPM_SUSPENDING) {
 631                 DEFINE_WAIT(wait);
 632
 633                 if (rpmflags & (RPM_ASYNC | RPM_NOWAIT)) {
 634                         if (dev->power.runtime_status == RPM_SUSPENDING)
 635                                 dev->power.deferred_resume = true;
 636                         else
 637                                 retval = -EINPROGRESS;
 638                         goto out;
 639                 }
 640
 641                 if (dev->power.irq_safe) {
 642                         spin_unlock(&dev->power.lock);
 643
 644                         cpu_relax();
 645
 646                         spin_lock(&dev->power.lock);
 647                         goto repeat;
 648                 }
 649
 650                 /* Wait for the operation carried out in parallel with us. */
 651                 for (;;) {
 652                         prepare_to_wait(&dev->power.wait_queue, &wait,
 653                                         TASK_UNINTERRUPTIBLE);
 654                         if (dev->power.runtime_status != RPM_RESUMING
 655                             && dev->power.runtime_status != RPM_SUSPENDING)
 656                                 break;
 657
 658                         spin_unlock_irq(&dev->power.lock);
 659
 660                         schedule();
 661
 662                         spin_lock_irq(&dev->power.lock);
 663                 }
 664                 finish_wait(&dev->power.wait_queue, &wait);
 665                 goto repeat;
 666         }
 667
 668         /*
 669          * See if we can skip waking up the parent.  This is safe only if
 670          * power.no_callbacks is set, because otherwise we don't know whether
 671          * the resume will actually succeed.
 672          */
 673         if (dev->power.no_callbacks && !parent && dev->parent) {
 674                 spin_lock_nested(&dev->parent->power.lock, SINGLE_DEPTH_NESTING);
 675                 if (dev->parent->power.disable_depth > 0
 676                     || dev->parent->power.ignore_children
 677                     || dev->parent->power.runtime_status == RPM_ACTIVE) {
 678                         atomic_inc(&dev->parent->power.child_count);
 679                         spin_unlock(&dev->parent->power.lock);
 680                         retval = 1;
 681                         goto no_callback;       /* Assume success. */
 682                 }
 683                 spin_unlock(&dev->parent->power.lock);
 684         }
 685
 686         /* Carry out an asynchronous or a synchronous resume. */
 687         if (rpmflags & RPM_ASYNC) {
 688                 dev->power.request = RPM_REQ_RESUME;
 689                 if (!dev->power.request_pending) {
 690                         dev->power.request_pending = true;
 691                         queue_work(pm_wq, &dev->power.work);
 692                 }
 693                 retval = 0;
 694                 goto out;
 695         }
 696
 697         if (!parent && dev->parent) {
 698                 /*
 699                  * Increment the parent's usage counter and resume it if
 700                  * necessary.  Not needed if dev is irq-safe; then the
 701                  * parent is permanently resumed.
 702                  */
 703                 parent = dev->parent;
 704                 if (dev->power.irq_safe)
 705                         goto skip_parent;
 706                 spin_unlock(&dev->power.lock);
 707
 708                 pm_runtime_get_noresume(parent);
 709
 710                 spin_lock(&parent->power.lock);
 711                 /*
 712                  * We can resume if the parent's runtime PM is disabled or it
 713                  * is set to ignore children.
 714                  */
 715                 if (!parent->power.disable_depth
 716                     && !parent->power.ignore_children) {
 717                         rpm_resume(parent, 0);
 718                         if (parent->power.runtime_status != RPM_ACTIVE)
 719                                 retval = -EBUSY;
 720                 }
 721                 spin_unlock(&parent->power.lock);
 722
 723                 spin_lock(&dev->power.lock);
 724                 if (retval)
 725                         goto out;
 726                 goto repeat;
 727         }
 728  skip_parent:
 729
 730         if (dev->power.no_callbacks)
 731                 goto no_callback;       /* Assume success. */
 732
 733         __update_runtime_status(dev, RPM_RESUMING);
 734
 735         callback = RPM_GET_CALLBACK(dev, runtime_resume);
 736
 737         retval = rpm_callback(callback, dev);
 738         if (retval) {
 739                 __update_runtime_status(dev, RPM_SUSPENDED);
 740                 pm_runtime_cancel_pending(dev);
 741         } else {
 742  no_callback:
 743                 __update_runtime_status(dev, RPM_ACTIVE);
 744                 pm_runtime_mark_last_busy(dev);
 745                 if (parent)
 746                         atomic_inc(&parent->power.child_count);
 747         }
 748         wake_up_all(&dev->power.wait_queue);
 749
 750         if (retval >= 0)
 751                 rpm_idle(dev, RPM_ASYNC);
 752
 753  out:
 754         if (parent && !dev->power.irq_safe) {
 755                 spin_unlock_irq(&dev->power.lock);
 756
 757                 pm_runtime_put(parent);
 758
 759                 spin_lock_irq(&dev->power.lock);
 760         }
 761
 762         trace_rpm_return_int(dev, _THIS_IP_, retval);
 763
 764         return retval;
 765 }
 766
 767 /**
 768  * pm_runtime_work - Universal runtime PM work function.
 769  * @work: Work structure used for scheduling the execution of this function.
 770  *
 771  * Use @work to get the device object the work is to be done for, determine what
 772  * is to be done and execute the appropriate runtime PM function.
 773  */
 774 static void pm_runtime_work(struct work_struct *work)
 775 {
 776         struct device *dev = container_of(work, struct device, power.work);
 777         enum rpm_request req;
 778
 779         spin_lock_irq(&dev->power.lock);
 780
 781         if (!dev->power.request_pending)
 782                 goto out;
 783
 784         req = dev->power.request;
 785         dev->power.request = RPM_REQ_NONE;
 786         dev->power.request_pending = false;
 787
 788         switch (req) {
 789         case RPM_REQ_NONE:
 790                 break;
 791         case RPM_REQ_IDLE:
 792                 rpm_idle(dev, RPM_NOWAIT);
 793                 break;
 794         case RPM_REQ_SUSPEND:
 795                 rpm_suspend(dev, RPM_NOWAIT);
 796                 break;
 797         case RPM_REQ_AUTOSUSPEND:
 798                 rpm_suspend(dev, RPM_NOWAIT | RPM_AUTO);
 799                 break;
 800         case RPM_REQ_RESUME:
 801                 rpm_resume(dev, RPM_NOWAIT);
 802                 break;
 803         }
 804
 805  out:
 806         spin_unlock_irq(&dev->power.lock);
 807 }
 808
 809 /**
 810  * pm_suspend_timer_fn - Timer function for pm_schedule_suspend().
 811  * @data: Device pointer passed by pm_schedule_suspend().
 812  *
 813  * Check if the time is right and queue a suspend request.
 814  */
 815 static void pm_suspend_timer_fn(unsigned long data)
 816 {
 817         struct device *dev = (struct device *)data;
 818         unsigned long flags;
 819         unsigned long expires;
 820
 821         spin_lock_irqsave(&dev->power.lock, flags);
 822
 823         expires = dev->power.timer_expires;
 824         /* If 'expire' is after 'jiffies' we've been called too early. */
 825         if (expires > 0 && !time_after(expires, jiffies)) {
 826                 dev->power.timer_expires = 0;
 827                 rpm_suspend(dev, dev->power.timer_autosuspends ?
 828                     (RPM_ASYNC | RPM_AUTO) : RPM_ASYNC);
 829         }
 830
 831         spin_unlock_irqrestore(&dev->power.lock, flags);
 832 }
 833
 834 /**
 835  * pm_schedule_suspend - Set up a timer to submit a suspend request in future.
 836  * @dev: Device to suspend.
 837  * @delay: Time to wait before submitting a suspend request, in milliseconds.
 838  */
 839 int pm_schedule_suspend(struct device *dev, unsigned int delay)
 840 {
 841         unsigned long flags;
 842         int retval;
 843
 844         spin_lock_irqsave(&dev->power.lock, flags);
 845
 846         if (!delay) {
 847                 retval = rpm_suspend(dev, RPM_ASYNC);
 848                 goto out;
 849         }
 850
 851         retval = rpm_check_suspend_allowed(dev);
 852         if (retval)
 853                 goto out;
 854
 855         /* Other scheduled or pending requests need to be canceled. */
 856         pm_runtime_cancel_pending(dev);
 857
 858         dev->power.timer_expires = jiffies + msecs_to_jiffies(delay);
 859         dev->power.timer_expires += !dev->power.timer_expires;
 860         dev->power.timer_autosuspends = 0;
 861         mod_timer(&dev->power.suspend_timer, dev->power.timer_expires);
 862
 863  out:
 864         spin_unlock_irqrestore(&dev->power.lock, flags);
 865
 866         return retval;
 867 }
 868 EXPORT_SYMBOL_GPL(pm_schedule_suspend);
 869
 870 /**
 871  * __pm_runtime_idle - Entry point for runtime idle operations.
 872  * @dev: Device to send idle notification for.
 873  * @rpmflags: Flag bits.
 874  *
 875  * If the RPM_GET_PUT flag is set, decrement the device's usage count and
 876  * return immediately if it is larger than zero.  Then carry out an idle
 877  * notification, either synchronous or asynchronous.
 878  *
 879  * This routine may be called in atomic context if the RPM_ASYNC flag is set,
 880  * or if pm_runtime_irq_safe() has been called.
 881  */
 882 int __pm_runtime_idle(struct device *dev, int rpmflags)
 883 {
 884         unsigned long flags;
 885         int retval;
 886
 887         might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);
 888
 889         if (rpmflags & RPM_GET_PUT) {
 890                 if (!atomic_dec_and_test(&dev->power.usage_count))
 891                         return 0;
 892         }
 893
 894         spin_lock_irqsave(&dev->power.lock, flags);
 895         retval = rpm_idle(dev, rpmflags);
 896         spin_unlock_irqrestore(&dev->power.lock, flags);
 897
 898         return retval;
 899 }
 900 EXPORT_SYMBOL_GPL(__pm_runtime_idle);
 901
 902 /**
 903  * __pm_runtime_suspend - Entry point for runtime put/suspend operations.
 904  * @dev: Device to suspend.
 905  * @rpmflags: Flag bits.
 906  *
 907  * If the RPM_GET_PUT flag is set, decrement the device's usage count and
 908  * return immediately if it is larger than zero.  Then carry out a suspend,
 909  * either synchronous or asynchronous.
 910  *
 911  * This routine may be called in atomic context if the RPM_ASYNC flag is set,
 912  * or if pm_runtime_irq_safe() has been called.
 913  */
 914 int __pm_runtime_suspend(struct device *dev, int rpmflags)
 915 {
 916         unsigned long flags;
 917         int retval;
 918
 919         might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);
 920
 921         if (rpmflags & RPM_GET_PUT) {
 922                 if (!atomic_dec_and_test(&dev->power.usage_count))
 923                         return 0;
 924         }
 925
 926         spin_lock_irqsave(&dev->power.lock, flags);
 927         retval = rpm_suspend(dev, rpmflags);
 928         spin_unlock_irqrestore(&dev->power.lock, flags);
 929
 930         return retval;
 931 }
 932 EXPORT_SYMBOL_GPL(__pm_runtime_suspend);
 933
 934 /**
 935  * __pm_runtime_resume - Entry point for runtime resume operations.
 936  * @dev: Device to resume.
 937  * @rpmflags: Flag bits.
 938  *
 939  * If the RPM_GET_PUT flag is set, increment the device's usage count.  Then
 940  * carry out a resume, either synchronous or asynchronous.
 941  *
 942  * This routine may be called in atomic context if the RPM_ASYNC flag is set,
 943  * or if pm_runtime_irq_safe() has been called.
 944  */
 945 int __pm_runtime_resume(struct device *dev, int rpmflags)
 946 {
 947         unsigned long flags;
 948         int retval;
 949
 950         might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);
 951
 952         if (rpmflags & RPM_GET_PUT)
 953                 atomic_inc(&dev->power.usage_count);
 954
 955         spin_lock_irqsave(&dev->power.lock, flags);
 956         retval = rpm_resume(dev, rpmflags);
 957         spin_unlock_irqrestore(&dev->power.lock, flags);
 958
 959         return retval;
 960 }
 961 EXPORT_SYMBOL_GPL(__pm_runtime_resume);
 962
 963 /**
 964  * __pm_runtime_set_status - Set runtime PM status of a device.
 965  * @dev: Device to handle.
 966  * @status: New runtime PM status of the device.
 967  *
 968  * If runtime PM of the device is disabled or its power.runtime_error field is
 969  * different from zero, the status may be changed either to RPM_ACTIVE, or to
 970  * RPM_SUSPENDED, as long as that reflects the actual state of the device.
 971  * However, if the device has a parent and the parent is not active, and the
 972  * parent's power.ignore_children flag is unset, the device's status cannot be
 973  * set to RPM_ACTIVE, so -EBUSY is returned in that case.
 974  *
 975  * If successful, __pm_runtime_set_status() clears the power.runtime_error field
 976  * and the device parent's counter of unsuspended children is modified to
 977  * reflect the new status.  If the new status is RPM_SUSPENDED, an idle
 978  * notification request for the parent is submitted.
 979  */
 980 int __pm_runtime_set_status(struct device *dev, unsigned int status)
 981 {
 982         struct device *parent = dev->parent;
 983         unsigned long flags;
 984         bool notify_parent = false;
 985         int error = 0;
 986
 987         if (status != RPM_ACTIVE && status != RPM_SUSPENDED)
 988                 return -EINVAL;
 989
 990         spin_lock_irqsave(&dev->power.lock, flags);
 991
 992         if (!dev->power.runtime_error && !dev->power.disable_depth) {
 993                 error = -EAGAIN;
 994                 goto out;
 995         }
 996
 997         if (dev->power.runtime_status == status)
 998                 goto out_set;
 999
1000         if (status == RPM_SUSPENDED) {
1001                 /* It always is possible to set the status to 'suspended'. */
1002                 if (parent) {
1003                         atomic_add_unless(&parent->power.child_count, -1, 0);
1004                         notify_parent = !parent->power.ignore_children;
1005                 }
1006                 goto out_set;
1007         }
1008
1009         if (parent) {
1010                 spin_lock_nested(&parent->power.lock, SINGLE_DEPTH_NESTING);
1011
1012                 /*
1013                  * It is invalid to put an active child under a parent that is
1014                  * not active, has runtime PM enabled and the
1015                  * 'power.ignore_children' flag unset.
1016                  */
1017                 if (!parent->power.disable_depth
1018                     && !parent->power.ignore_children
1019                     && parent->power.runtime_status != RPM_ACTIVE)
1020                         error = -EBUSY;
1021                 else if (dev->power.runtime_status == RPM_SUSPENDED)
1022                         atomic_inc(&parent->power.child_count);
1023
1024                 spin_unlock(&parent->power.lock);
1025
1026                 if (error)
1027                         goto out;
1028         }
1029
1030  out_set:
1031         __update_runtime_status(dev, status);
1032         dev->power.runtime_error = 0;
1033  out:
1034         spin_unlock_irqrestore(&dev->power.lock, flags);
1035
1036         if (notify_parent)
1037                 pm_request_idle(parent);
1038
1039         return error;
1040 }
1041 EXPORT_SYMBOL_GPL(__pm_runtime_set_status);
1042
1043 /**
1044  * __pm_runtime_barrier - Cancel pending requests and wait for completions.
1045  * @dev: Device to handle.
1046  *
1047  * Flush all pending requests for the device from pm_wq and wait for all
1048  * runtime PM operations involving the device in progress to complete.
1049  *
1050  * Should be called under dev->power.lock with interrupts disabled.
1051  */
1052 static void __pm_runtime_barrier(struct device *dev)
1053 {
1054         pm_runtime_deactivate_timer(dev);
1055
1056         if (dev->power.request_pending) {
1057                 dev->power.request = RPM_REQ_NONE;
1058                 spin_unlock_irq(&dev->power.lock);
1059
1060                 cancel_work_sync(&dev->power.work);
1061
1062                 spin_lock_irq(&dev->power.lock);
1063                 dev->power.request_pending = false;
1064         }
1065
1066         if (dev->power.runtime_status == RPM_SUSPENDING
1067             || dev->power.runtime_status == RPM_RESUMING
1068             || dev->power.idle_notification) {
1069                 DEFINE_WAIT(wait);
1070
1071                 /* Suspend, wake-up or idle notification in progress. */
1072                 for (;;) {
1073                         prepare_to_wait(&dev->power.wait_queue, &wait,
1074                                         TASK_UNINTERRUPTIBLE);
1075                         if (dev->power.runtime_status != RPM_SUSPENDING
1076                             && dev->power.runtime_status != RPM_RESUMING
1077                             && !dev->power.idle_notification)
1078                                 break;
1079                         spin_unlock_irq(&dev->power.lock);
1080
1081                         schedule();
1082
1083                         spin_lock_irq(&dev->power.lock);
1084                 }
1085                 finish_wait(&dev->power.wait_queue, &wait);
1086         }
1087 }
1088
1089 /**
1090  * pm_runtime_barrier - Flush pending requests and wait for completions.
1091  * @dev: Device to handle.
1092  *
1093  * Prevent the device from being suspended by incrementing its usage counter and
1094  * if there's a pending resume request for the device, wake the device up.
1095  * Next, make sure that all pending requests for the device have been flushed
1096  * from pm_wq and wait for all runtime PM operations involving the device in
1097  * progress to complete.
1098  *
1099  * Return value:
1100  * 1, if there was a resume request pending and the device had to be woken up,
1101  * 0, otherwise
1102  */
1103 int pm_runtime_barrier(struct device *dev)
1104 {
1105         int retval = 0;
1106
1107         pm_runtime_get_noresume(dev);
1108         spin_lock_irq(&dev->power.lock);
1109
1110         if (dev->power.request_pending
1111             && dev->power.request == RPM_REQ_RESUME) {
1112                 rpm_resume(dev, 0);
1113                 retval = 1;
1114         }
1115
1116         __pm_runtime_barrier(dev);
1117
1118         spin_unlock_irq(&dev->power.lock);
1119         pm_runtime_put_noidle(dev);
1120
1121         return retval;
1122 }
1123 EXPORT_SYMBOL_GPL(pm_runtime_barrier);
1124
1125 /**
1126  * __pm_runtime_disable - Disable runtime PM of a device.
1127  * @dev: Device to handle.
1128  * @check_resume: If set, check if there's a resume request for the device.
1129  *
1130  * Increment power.disable_depth for the device and if it was zero previously,
1131  * cancel all pending runtime PM requests for the device and wait for all
1132  * operations in progress to complete.  The device can be either active or
1133  * suspended after its runtime PM has been disabled.
1134  *
1135  * If @check_resume is set and there's a resume request pending when
1136  * __pm_runtime_disable() is called and power.disable_depth is zero, the
1137  * function will wake up the device before disabling its runtime PM.
1138  */
1139 void __pm_runtime_disable(struct device *dev, bool check_resume)
1140 {
1141         spin_lock_irq(&dev->power.lock);
1142
1143         if (dev->power.disable_depth > 0) {
1144                 dev->power.disable_depth++;
1145                 goto out;
1146         }
1147
1148         /*
1149          * Wake up the device if there's a resume request pending, because that
1150          * means there probably is some I/O to process and disabling runtime PM
1151          * shouldn't prevent the device from processing the I/O.
1152          */
1153         if (check_resume && dev->power.request_pending
1154             && dev->power.request == RPM_REQ_RESUME) {
1155                 /*
1156                  * Prevent suspends and idle notifications from being carried
1157                  * out after we have woken up the device.
1158                  */
1159                 pm_runtime_get_noresume(dev);
1160
1161                 rpm_resume(dev, 0);
1162
1163                 pm_runtime_put_noidle(dev);
1164         }
1165
1166         if (!dev->power.disable_depth++)
1167                 __pm_runtime_barrier(dev);
1168
1169  out:
1170         spin_unlock_irq(&dev->power.lock);
1171 }
1172 EXPORT_SYMBOL_GPL(__pm_runtime_disable);
1173
1174 /**
1175  * pm_runtime_enable - Enable runtime PM of a device.
1176  * @dev: Device to handle.
1177  */
1178 void pm_runtime_enable(struct device *dev)
1179 {
1180         unsigned long flags;
1181
1182         spin_lock_irqsave(&dev->power.lock, flags);
1183
1184         if (dev->power.disable_depth > 0)
1185                 dev->power.disable_depth--;
1186         else
1187                 dev_warn(dev, "Unbalanced %s!\n", __func__);
1188
1189         spin_unlock_irqrestore(&dev->power.lock, flags);
1190 }
1191 EXPORT_SYMBOL_GPL(pm_runtime_enable);
1192
1193 /**
1194  * pm_runtime_forbid - Block runtime PM of a device.
1195  * @dev: Device to handle.
1196  *
1197  * Increase the device's usage count and clear its power.runtime_auto flag,
1198  * so that it cannot be suspended at run time until pm_runtime_allow() is called
1199  * for it.
1200  */
1201 void pm_runtime_forbid(struct device *dev)
1202 {
1203         spin_lock_irq(&dev->power.lock);
1204         if (!dev->power.runtime_auto)
1205                 goto out;
1206
1207         dev->power.runtime_auto = false;
1208         atomic_inc(&dev->power.usage_count);
1209         rpm_resume(dev, 0);
1210
1211  out:
1212         spin_unlock_irq(&dev->power.lock);
1213 }
1214 EXPORT_SYMBOL_GPL(pm_runtime_forbid);
1215
1216 /**
1217  * pm_runtime_allow - Unblock runtime PM of a device.
1218  * @dev: Device to handle.
1219  *
1220  * Decrease the device's usage count and set its power.runtime_auto flag.
1221  */
1222 void pm_runtime_allow(struct device *dev)
1223 {
1224         spin_lock_irq(&dev->power.lock);
1225         if (dev->power.runtime_auto)
1226                 goto out;
1227
1228         dev->power.runtime_auto = true;
1229         if (atomic_dec_and_test(&dev->power.usage_count))
1230                 rpm_idle(dev, RPM_AUTO);
1231
1232  out:
1233         spin_unlock_irq(&dev->power.lock);
1234 }
1235 EXPORT_SYMBOL_GPL(pm_runtime_allow);
1236
1237 /**
1238  * pm_runtime_no_callbacks - Ignore runtime PM callbacks for a device.
1239  * @dev: Device to handle.
1240  *
1241  * Set the power.no_callbacks flag, which tells the PM core that this
1242  * device is power-managed through its parent and has no runtime PM
1243  * callbacks of its own.  The runtime sysfs attributes will be removed.
1244  */
1245 void pm_runtime_no_callbacks(struct device *dev)
1246 {
1247         spin_lock_irq(&dev->power.lock);
1248         dev->power.no_callbacks = 1;
1249         spin_unlock_irq(&dev->power.lock);
1250         if (device_is_registered(dev))
1251                 rpm_sysfs_remove(dev);
1252 }
1253 EXPORT_SYMBOL_GPL(pm_runtime_no_callbacks);
1254
1255 /**
1256  * pm_runtime_irq_safe - Leave interrupts disabled during callbacks.
1257  * @dev: Device to handle
1258  *
1259  * Set the power.irq_safe flag, which tells the PM core that the
1260  * ->runtime_suspend() and ->runtime_resume() callbacks for this device should
1261  * always be invoked with the spinlock held and interrupts disabled.  It also
1262  * causes the parent's usage counter to be permanently incremented, preventing
1263  * the parent from runtime suspending -- otherwise an irq-safe child might have
1264  * to wait for a non-irq-safe parent.
1265  */
1266 void pm_runtime_irq_safe(struct device *dev)
1267 {
1268         if (dev->parent)
1269                 pm_runtime_get_sync(dev->parent);
1270         spin_lock_irq(&dev->power.lock);
1271         dev->power.irq_safe = 1;
1272         spin_unlock_irq(&dev->power.lock);
1273 }
1274 EXPORT_SYMBOL_GPL(pm_runtime_irq_safe);
1275
1276 /**
1277  * update_autosuspend - Handle a change to a device's autosuspend settings.
1278  * @dev: Device to handle.
1279  * @old_delay: The former autosuspend_delay value.
1280  * @old_use: The former use_autosuspend value.
1281  *
1282  * Prevent runtime suspend if the new delay is negative and use_autosuspend is
1283  * set; otherwise allow it.  Send an idle notification if suspends are allowed.
1284  *
1285  * This function must be called under dev->power.lock with interrupts disabled.
1286  */
1287 static void update_autosuspend(struct device *dev, int old_delay, int old_use)
1288 {
1289         int delay = dev->power.autosuspend_delay;
1290
1291         /* Should runtime suspend be prevented now? */
1292         if (dev->power.use_autosuspend && delay < 0) {
1293
1294                 /* If it used to be allowed then prevent it. */
1295                 if (!old_use || old_delay >= 0) {
1296                         atomic_inc(&dev->power.usage_count);
1297                         rpm_resume(dev, 0);
1298                 }
1299         }
1300
1301         /* Runtime suspend should be allowed now. */
1302         else {
1303
1304                 /* If it used to be prevented then allow it. */
1305                 if (old_use && old_delay < 0)
1306                         atomic_dec(&dev->power.usage_count);
1307
1308                 /* Maybe we can autosuspend now. */
1309                 rpm_idle(dev, RPM_AUTO);
1310         }
1311 }
1312
1313 /**
1314  * pm_runtime_set_autosuspend_delay - Set a device's autosuspend_delay value.
1315  * @dev: Device to handle.
1316  * @delay: Value of the new delay in milliseconds.
1317  *
1318  * Set the device's power.autosuspend_delay value.  If it changes to negative
1319  * and the power.use_autosuspend flag is set, prevent runtime suspends.  If it
1320  * changes the other way, allow runtime suspends.
1321  */
1322 void pm_runtime_set_autosuspend_delay(struct device *dev, int delay)
1323 {
1324         int old_delay, old_use;
1325
1326         spin_lock_irq(&dev->power.lock);
1327         old_delay = dev->power.autosuspend_delay;
1328         old_use = dev->power.use_autosuspend;
1329         dev->power.autosuspend_delay = delay;
1330         update_autosuspend(dev, old_delay, old_use);
1331         spin_unlock_irq(&dev->power.lock);
1332 }
1333 EXPORT_SYMBOL_GPL(pm_runtime_set_autosuspend_delay);
1334
1335 /**
1336  * __pm_runtime_use_autosuspend - Set a device's use_autosuspend flag.
1337  * @dev: Device to handle.
1338  * @use: New value for use_autosuspend.
1339  *
1340  * Set the device's power.use_autosuspend flag, and allow or prevent runtime
1341  * suspends as needed.
1342  */
1343 void __pm_runtime_use_autosuspend(struct device *dev, bool use)
1344 {
1345         int old_delay, old_use;
1346
1347         spin_lock_irq(&dev->power.lock);
1348         old_delay = dev->power.autosuspend_delay;
1349         old_use = dev->power.use_autosuspend;
1350         dev->power.use_autosuspend = use;
1351         update_autosuspend(dev, old_delay, old_use);
1352         spin_unlock_irq(&dev->power.lock);
1353 }
1354 EXPORT_SYMBOL_GPL(__pm_runtime_use_autosuspend);
1355
1356 /**
1357  * pm_runtime_init - Initialize runtime PM fields in given device object.
1358  * @dev: Device object to initialize.
1359  */
1360 void pm_runtime_init(struct device *dev)
1361 {
1362         dev->power.runtime_status = RPM_SUSPENDED;
1363         dev->power.idle_notification = false;
1364
1365         dev->power.disable_depth = 1;
1366         atomic_set(&dev->power.usage_count, 0);
1367
1368         dev->power.runtime_error = 0;
1369
1370         atomic_set(&dev->power.child_count, 0);
1371         pm_suspend_ignore_children(dev, false);
1372         dev->power.runtime_auto = true;
1373
1374         dev->power.request_pending = false;
1375         dev->power.request = RPM_REQ_NONE;
1376         dev->power.deferred_resume = false;
1377         dev->power.accounting_timestamp = jiffies;
1378         INIT_WORK(&dev->power.work, pm_runtime_work);
1379
1380         dev->power.timer_expires = 0;
1381         setup_timer(&dev->power.suspend_timer, pm_suspend_timer_fn,
1382                         (unsigned long)dev);
1383
1384         init_waitqueue_head(&dev->power.wait_queue);
1385 }
1386
1387 /**
1388  * pm_runtime_remove - Prepare for removing a device from device hierarchy.
1389  * @dev: Device object being removed from device hierarchy.
1390  */
1391 void pm_runtime_remove(struct device *dev)
1392 {
1393         __pm_runtime_disable(dev, false);
1394
1395         /* Change the status back to 'suspended' to match the initial status. */
1396         if (dev->power.runtime_status == RPM_ACTIVE)
1397                 pm_runtime_set_suspended(dev);
1398         if (dev->power.irq_safe && dev->parent)
1399                 pm_runtime_put(dev->parent);
1400 }
1401
1402 /**
1403  * pm_runtime_force_suspend - Force a device into suspend state if needed.
1404  * @dev: Device to suspend.
1405  *
1406  * Disable runtime PM so we safely can check the device's runtime PM status and
1407  * if it is active, invoke it's .runtime_suspend callback to bring it into
1408  * suspend state. Keep runtime PM disabled to preserve the state unless we
1409  * encounter errors.
1410  *
1411  * Typically this function may be invoked from a system suspend callback to make
1412  * sure the device is put into low power state.
1413  */
1414 int pm_runtime_force_suspend(struct device *dev)
1415 {
1416         int (*callback)(struct device *);
1417         int ret = 0;
1418
1419         pm_runtime_disable(dev);
1420         if (pm_runtime_status_suspended(dev))
1421                 return 0;
1422
1423         callback = RPM_GET_CALLBACK(dev, runtime_suspend);
1424
1425         if (!callback) {
1426                 ret = -ENOSYS;
1427                 goto err;
1428         }
1429
1430         ret = callback(dev);
1431         if (ret)
1432                 goto err;
1433
1434         pm_runtime_set_suspended(dev);
1435         return 0;
1436 err:
1437         pm_runtime_enable(dev);
1438         return ret;
1439 }
1440 EXPORT_SYMBOL_GPL(pm_runtime_force_suspend);
1441
1442 /**
1443  * pm_runtime_force_resume - Force a device into resume state.
1444  * @dev: Device to resume.
1445  *
1446  * Prior invoking this function we expect the user to have brought the device
1447  * into low power state by a call to pm_runtime_force_suspend(). Here we reverse
1448  * those actions and brings the device into full power. We update the runtime PM
1449  * status and re-enables runtime PM.
1450  *
1451  * Typically this function may be invoked from a system resume callback to make
1452  * sure the device is put into full power state.
1453  */
1454 int pm_runtime_force_resume(struct device *dev)
1455 {
1456         int (*callback)(struct device *);
1457         int ret = 0;
1458
1459         callback = RPM_GET_CALLBACK(dev, runtime_resume);
1460
1461         if (!callback) {
1462                 ret = -ENOSYS;
1463                 goto out;
1464         }
1465
1466         ret = callback(dev);
1467         if (ret)
1468                 goto out;
1469
1470         pm_runtime_set_active(dev);
1471         pm_runtime_mark_last_busy(dev);
1472 out:
1473         pm_runtime_enable(dev);
1474         return ret;
1475 }
1476 EXPORT_SYMBOL_GPL(pm_runtime_force_resume);