drivers/base/power/runtime.c

   1 /*
   2  * drivers/base/power/runtime.c - Helper functions for device run-time PM
   3  *
   4  * Copyright (c) 2009 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
   5  *
   6  * This file is released under the GPLv2.
   7  */
   8
   9 #include <linux/sched.h>
  10 #include <linux/pm_runtime.h>
  11 #include <linux/jiffies.h>
  12
  13 static int __pm_runtime_resume(struct device *dev, bool from_wq);
  14 static int __pm_request_idle(struct device *dev);
  15 static int __pm_request_resume(struct device *dev);
  16
  17 /**
  18  * pm_runtime_deactivate_timer - Deactivate given device's suspend timer.
  19  * @dev: Device to handle.
  20  */
  21 static void pm_runtime_deactivate_timer(struct device *dev)
  22 {
  23         if (dev->power.timer_expires > 0) {
  24                 del_timer(&dev->power.suspend_timer);
  25                 dev->power.timer_expires = 0;
  26         }
  27 }
  28
  29 /**
  30  * pm_runtime_cancel_pending - Deactivate suspend timer and cancel requests.
  31  * @dev: Device to handle.
  32  */
  33 static void pm_runtime_cancel_pending(struct device *dev)
  34 {
  35         pm_runtime_deactivate_timer(dev);
  36         /*
  37          * In case there's a request pending, make sure its work function will
  38          * return without doing anything.
  39          */
  40         dev->power.request = RPM_REQ_NONE;
  41 }
  42
  43 /**
  44  * __pm_runtime_idle - Notify device bus type if the device can be suspended.
  45  * @dev: Device to notify the bus type about.
  46  *
  47  * This function must be called under dev->power.lock with interrupts disabled.
  48  */
  49 static int __pm_runtime_idle(struct device *dev)
  50         __releases(&dev->power.lock) __acquires(&dev->power.lock)
  51 {
  52         int retval = 0;
  53
  54         if (dev->power.runtime_error)
  55                 retval = -EINVAL;
  56         else if (dev->power.idle_notification)
  57                 retval = -EINPROGRESS;
  58         else if (atomic_read(&dev->power.usage_count) > 0
  59             || dev->power.disable_depth > 0
  60             || dev->power.runtime_status != RPM_ACTIVE)
  61                 retval = -EAGAIN;
  62         else if (!pm_children_suspended(dev))
  63                 retval = -EBUSY;
  64         if (retval)
  65                 goto out;
  66
  67         if (dev->power.request_pending) {
  68                 /*
  69                  * If an idle notification request is pending, cancel it.  Any
  70                  * other pending request takes precedence over us.
  71                  */
  72                 if (dev->power.request == RPM_REQ_IDLE) {
  73                         dev->power.request = RPM_REQ_NONE;
  74                 } else if (dev->power.request != RPM_REQ_NONE) {
  75                         retval = -EAGAIN;
  76                         goto out;
  77                 }
  78         }
  79
  80         dev->power.idle_notification = true;
  81
  82         if (dev->bus && dev->bus->pm && dev->bus->pm->runtime_idle) {
  83                 spin_unlock_irq(&dev->power.lock);
  84
  85                 dev->bus->pm->runtime_idle(dev);
  86
  87                 spin_lock_irq(&dev->power.lock);
  88         }
  89
  90         dev->power.idle_notification = false;
  91         wake_up_all(&dev->power.wait_queue);
  92
  93  out:
  94         return retval;
  95 }
  96
  97 /**
  98  * pm_runtime_idle - Notify device bus type if the device can be suspended.
  99  * @dev: Device to notify the bus type about.
 100  */
 101 int pm_runtime_idle(struct device *dev)
 102 {
 103         int retval;
 104
 105         spin_lock_irq(&dev->power.lock);
 106         retval = __pm_runtime_idle(dev);
 107         spin_unlock_irq(&dev->power.lock);
 108
 109         return retval;
 110 }
 111 EXPORT_SYMBOL_GPL(pm_runtime_idle);
 112
 113 /**
 114  * __pm_runtime_suspend - Carry out run-time suspend of given device.
 115  * @dev: Device to suspend.
 116  * @from_wq: If set, the function has been called via pm_wq.
 117  *
 118  * Check if the device can be suspended and run the ->runtime_suspend() callback
 119  * provided by its bus type.  If another suspend has been started earlier, wait
 120  * for it to finish.  If an idle notification or suspend request is pending or
 121  * scheduled, cancel it.
 122  *
 123  * This function must be called under dev->power.lock with interrupts disabled.
 124  */
 125 int __pm_runtime_suspend(struct device *dev, bool from_wq)
 126         __releases(&dev->power.lock) __acquires(&dev->power.lock)
 127 {
 128         struct device *parent = NULL;
 129         bool notify = false;
 130         int retval = 0;
 131
 132         dev_dbg(dev, "__pm_runtime_suspend()%s!\n",
 133                 from_wq ? " from workqueue" : "");
 134
 135  repeat:
 136         if (dev->power.runtime_error) {
 137                 retval = -EINVAL;
 138                 goto out;
 139         }
 140
 141         /* Pending resume requests take precedence over us. */
 142         if (dev->power.request_pending
 143             && dev->power.request == RPM_REQ_RESUME) {
 144                 retval = -EAGAIN;
 145                 goto out;
 146         }
 147
 148         /* Other scheduled or pending requests need to be canceled. */
 149         pm_runtime_cancel_pending(dev);
 150
 151         if (dev->power.runtime_status == RPM_SUSPENDED)
 152                 retval = 1;
 153         else if (dev->power.runtime_status == RPM_RESUMING
 154             || dev->power.disable_depth > 0
 155             || atomic_read(&dev->power.usage_count) > 0)
 156                 retval = -EAGAIN;
 157         else if (!pm_children_suspended(dev))
 158                 retval = -EBUSY;
 159         if (retval)
 160                 goto out;
 161
 162         if (dev->power.runtime_status == RPM_SUSPENDING) {
 163                 DEFINE_WAIT(wait);
 164
 165                 if (from_wq) {
 166                         retval = -EINPROGRESS;
 167                         goto out;
 168                 }
 169
 170                 /* Wait for the other suspend running in parallel with us. */
 171                 for (;;) {
 172                         prepare_to_wait(&dev->power.wait_queue, &wait,
 173                                         TASK_UNINTERRUPTIBLE);
 174                         if (dev->power.runtime_status != RPM_SUSPENDING)
 175                                 break;
 176
 177                         spin_unlock_irq(&dev->power.lock);
 178
 179                         schedule();
 180
 181                         spin_lock_irq(&dev->power.lock);
 182                 }
 183                 finish_wait(&dev->power.wait_queue, &wait);
 184                 goto repeat;
 185         }
 186
 187         dev->power.runtime_status = RPM_SUSPENDING;
 188
 189         if (dev->bus && dev->bus->pm && dev->bus->pm->runtime_suspend) {
 190                 spin_unlock_irq(&dev->power.lock);
 191
 192                 retval = dev->bus->pm->runtime_suspend(dev);
 193
 194                 spin_lock_irq(&dev->power.lock);
 195                 dev->power.runtime_error = retval;
 196         } else {
 197                 retval = -ENOSYS;
 198         }
 199
 200         if (retval) {
 201                 dev->power.runtime_status = RPM_ACTIVE;
 202                 pm_runtime_cancel_pending(dev);
 203                 dev->power.deferred_resume = false;
 204
 205                 if (retval == -EAGAIN || retval == -EBUSY) {
 206                         notify = true;
 207                         dev->power.runtime_error = 0;
 208                 }
 209         } else {
 210                 dev->power.runtime_status = RPM_SUSPENDED;
 211
 212                 if (dev->parent) {
 213                         parent = dev->parent;
 214                         atomic_add_unless(&parent->power.child_count, -1, 0);
 215                 }
 216         }
 217         wake_up_all(&dev->power.wait_queue);
 218
 219         if (dev->power.deferred_resume) {
 220                 dev->power.deferred_resume = false;
 221                 __pm_runtime_resume(dev, false);
 222                 retval = -EAGAIN;
 223                 goto out;
 224         }
 225
 226         if (notify)
 227                 __pm_runtime_idle(dev);
 228
 229         if (parent && !parent->power.ignore_children) {
 230                 spin_unlock_irq(&dev->power.lock);
 231
 232                 pm_request_idle(parent);
 233
 234                 spin_lock_irq(&dev->power.lock);
 235         }
 236
 237  out:
 238         dev_dbg(dev, "__pm_runtime_suspend() returns %d!\n", retval);
 239
 240         return retval;
 241 }
 242
 243 /**
 244  * pm_runtime_suspend - Carry out run-time suspend of given device.
 245  * @dev: Device to suspend.
 246  */
 247 int pm_runtime_suspend(struct device *dev)
 248 {
 249         int retval;
 250
 251         spin_lock_irq(&dev->power.lock);
 252         retval = __pm_runtime_suspend(dev, false);
 253         spin_unlock_irq(&dev->power.lock);
 254
 255         return retval;
 256 }
 257 EXPORT_SYMBOL_GPL(pm_runtime_suspend);
 258
 259 /**
 260  * __pm_runtime_resume - Carry out run-time resume of given device.
 261  * @dev: Device to resume.
 262  * @from_wq: If set, the function has been called via pm_wq.
 263  *
 264  * Check if the device can be woken up and run the ->runtime_resume() callback
 265  * provided by its bus type.  If another resume has been started earlier, wait
 266  * for it to finish.  If there's a suspend running in parallel with this
 267  * function, wait for it to finish and resume the device.  Cancel any scheduled
 268  * or pending requests.
 269  *
 270  * This function must be called under dev->power.lock with interrupts disabled.
 271  */
 272 int __pm_runtime_resume(struct device *dev, bool from_wq)
 273         __releases(&dev->power.lock) __acquires(&dev->power.lock)
 274 {
 275         struct device *parent = NULL;
 276         int retval = 0;
 277
 278         dev_dbg(dev, "__pm_runtime_resume()%s!\n",
 279                 from_wq ? " from workqueue" : "");
 280
 281  repeat:
 282         if (dev->power.runtime_error) {
 283                 retval = -EINVAL;
 284                 goto out;
 285         }
 286
 287         pm_runtime_cancel_pending(dev);
 288
 289         if (dev->power.runtime_status == RPM_ACTIVE)
 290                 retval = 1;
 291         else if (dev->power.disable_depth > 0)
 292                 retval = -EAGAIN;
 293         if (retval)
 294                 goto out;
 295
 296         if (dev->power.runtime_status == RPM_RESUMING
 297             || dev->power.runtime_status == RPM_SUSPENDING) {
 298                 DEFINE_WAIT(wait);
 299
 300                 if (from_wq) {
 301                         if (dev->power.runtime_status == RPM_SUSPENDING)
 302                                 dev->power.deferred_resume = true;
 303                         retval = -EINPROGRESS;
 304                         goto out;
 305                 }
 306
 307                 /* Wait for the operation carried out in parallel with us. */
 308                 for (;;) {
 309                         prepare_to_wait(&dev->power.wait_queue, &wait,
 310                                         TASK_UNINTERRUPTIBLE);
 311                         if (dev->power.runtime_status != RPM_RESUMING
 312                             && dev->power.runtime_status != RPM_SUSPENDING)
 313                                 break;
 314
 315                         spin_unlock_irq(&dev->power.lock);
 316
 317                         schedule();
 318
 319                         spin_lock_irq(&dev->power.lock);
 320                 }
 321                 finish_wait(&dev->power.wait_queue, &wait);
 322                 goto repeat;
 323         }
 324
 325         if (!parent && dev->parent) {
 326                 /*
 327                  * Increment the parent's resume counter and resume it if
 328                  * necessary.
 329                  */
 330                 parent = dev->parent;
 331                 spin_unlock_irq(&dev->power.lock);
 332
 333                 pm_runtime_get_noresume(parent);
 334
 335                 spin_lock_irq(&parent->power.lock);
 336                 /*
 337                  * We can resume if the parent's run-time PM is disabled or it
 338                  * is set to ignore children.
 339                  */
 340                 if (!parent->power.disable_depth
 341                     && !parent->power.ignore_children) {
 342                         __pm_runtime_resume(parent, false);
 343                         if (parent->power.runtime_status != RPM_ACTIVE)
 344                                 retval = -EBUSY;
 345                 }
 346                 spin_unlock_irq(&parent->power.lock);
 347
 348                 spin_lock_irq(&dev->power.lock);
 349                 if (retval)
 350                         goto out;
 351                 goto repeat;
 352         }
 353
 354         dev->power.runtime_status = RPM_RESUMING;
 355
 356         if (dev->bus && dev->bus->pm && dev->bus->pm->runtime_resume) {
 357                 spin_unlock_irq(&dev->power.lock);
 358
 359                 retval = dev->bus->pm->runtime_resume(dev);
 360
 361                 spin_lock_irq(&dev->power.lock);
 362                 dev->power.runtime_error = retval;
 363         } else {
 364                 retval = -ENOSYS;
 365         }
 366
 367         if (retval) {
 368                 dev->power.runtime_status = RPM_SUSPENDED;
 369                 pm_runtime_cancel_pending(dev);
 370         } else {
 371                 dev->power.runtime_status = RPM_ACTIVE;
 372                 if (parent)
 373                         atomic_inc(&parent->power.child_count);
 374         }
 375         wake_up_all(&dev->power.wait_queue);
 376
 377         if (!retval)
 378                 __pm_request_idle(dev);
 379
 380  out:
 381         if (parent) {
 382                 spin_unlock_irq(&dev->power.lock);
 383
 384                 pm_runtime_put(parent);
 385
 386                 spin_lock_irq(&dev->power.lock);
 387         }
 388
 389         dev_dbg(dev, "__pm_runtime_resume() returns %d!\n", retval);
 390
 391         return retval;
 392 }
 393
 394 /**
 395  * pm_runtime_resume - Carry out run-time resume of given device.
 396  * @dev: Device to suspend.
 397  */
 398 int pm_runtime_resume(struct device *dev)
 399 {
 400         int retval;
 401
 402         spin_lock_irq(&dev->power.lock);
 403         retval = __pm_runtime_resume(dev, false);
 404         spin_unlock_irq(&dev->power.lock);
 405
 406         return retval;
 407 }
 408 EXPORT_SYMBOL_GPL(pm_runtime_resume);
 409
 410 /**
 411  * pm_runtime_work - Universal run-time PM work function.
 412  * @work: Work structure used for scheduling the execution of this function.
 413  *
 414  * Use @work to get the device object the work is to be done for, determine what
 415  * is to be done and execute the appropriate run-time PM function.
 416  */
 417 static void pm_runtime_work(struct work_struct *work)
 418 {
 419         struct device *dev = container_of(work, struct device, power.work);
 420         enum rpm_request req;
 421
 422         spin_lock_irq(&dev->power.lock);
 423
 424         if (!dev->power.request_pending)
 425                 goto out;
 426
 427         req = dev->power.request;
 428         dev->power.request = RPM_REQ_NONE;
 429         dev->power.request_pending = false;
 430
 431         switch (req) {
 432         case RPM_REQ_NONE:
 433                 break;
 434         case RPM_REQ_IDLE:
 435                 __pm_runtime_idle(dev);
 436                 break;
 437         case RPM_REQ_SUSPEND:
 438                 __pm_runtime_suspend(dev, true);
 439                 break;
 440         case RPM_REQ_RESUME:
 441                 __pm_runtime_resume(dev, true);
 442                 break;
 443         }
 444
 445  out:
 446         spin_unlock_irq(&dev->power.lock);
 447 }
 448
 449 /**
 450  * __pm_request_idle - Submit an idle notification request for given device.
 451  * @dev: Device to handle.
 452  *
 453  * Check if the device's run-time PM status is correct for suspending the device
 454  * and queue up a request to run __pm_runtime_idle() for it.
 455  *
 456  * This function must be called under dev->power.lock with interrupts disabled.
 457  */
 458 static int __pm_request_idle(struct device *dev)
 459 {
 460         int retval = 0;
 461
 462         if (dev->power.runtime_error)
 463                 retval = -EINVAL;
 464         else if (atomic_read(&dev->power.usage_count) > 0
 465             || dev->power.disable_depth > 0
 466             || dev->power.runtime_status == RPM_SUSPENDED
 467             || dev->power.runtime_status == RPM_SUSPENDING)
 468                 retval = -EAGAIN;
 469         else if (!pm_children_suspended(dev))
 470                 retval = -EBUSY;
 471         if (retval)
 472                 return retval;
 473
 474         if (dev->power.request_pending) {
 475                 /* Any requests other then RPM_REQ_IDLE take precedence. */
 476                 if (dev->power.request == RPM_REQ_NONE)
 477                         dev->power.request = RPM_REQ_IDLE;
 478                 else if (dev->power.request != RPM_REQ_IDLE)
 479                         retval = -EAGAIN;
 480                 return retval;
 481         }
 482
 483         dev->power.request = RPM_REQ_IDLE;
 484         dev->power.request_pending = true;
 485         queue_work(pm_wq, &dev->power.work);
 486
 487         return retval;
 488 }
 489
 490 /**
 491  * pm_request_idle - Submit an idle notification request for given device.
 492  * @dev: Device to handle.
 493  */
 494 int pm_request_idle(struct device *dev)
 495 {
 496         unsigned long flags;
 497         int retval;
 498
 499         spin_lock_irqsave(&dev->power.lock, flags);
 500         retval = __pm_request_idle(dev);
 501         spin_unlock_irqrestore(&dev->power.lock, flags);
 502
 503         return retval;
 504 }
 505 EXPORT_SYMBOL_GPL(pm_request_idle);
 506
 507 /**
 508  * __pm_request_suspend - Submit a suspend request for given device.
 509  * @dev: Device to suspend.
 510  *
 511  * This function must be called under dev->power.lock with interrupts disabled.
 512  */
 513 static int __pm_request_suspend(struct device *dev)
 514 {
 515         int retval = 0;
 516
 517         if (dev->power.runtime_error)
 518                 return -EINVAL;
 519
 520         if (dev->power.runtime_status == RPM_SUSPENDED)
 521                 retval = 1;
 522         else if (atomic_read(&dev->power.usage_count) > 0
 523             || dev->power.disable_depth > 0)
 524                 retval = -EAGAIN;
 525         else if (dev->power.runtime_status == RPM_SUSPENDING)
 526                 retval = -EINPROGRESS;
 527         else if (!pm_children_suspended(dev))
 528                 retval = -EBUSY;
 529         if (retval < 0)
 530                 return retval;
 531
 532         pm_runtime_deactivate_timer(dev);
 533
 534         if (dev->power.request_pending) {
 535                 /*
 536                  * Pending resume requests take precedence over us, but we can
 537                  * overtake any other pending request.
 538                  */
 539                 if (dev->power.request == RPM_REQ_RESUME)
 540                         retval = -EAGAIN;
 541                 else if (dev->power.request != RPM_REQ_SUSPEND)
 542                         dev->power.request = retval ?
 543                                                 RPM_REQ_NONE : RPM_REQ_SUSPEND;
 544                 return retval;
 545         } else if (retval) {
 546                 return retval;
 547         }
 548
 549         dev->power.request = RPM_REQ_SUSPEND;
 550         dev->power.request_pending = true;
 551         queue_work(pm_wq, &dev->power.work);
 552
 553         return 0;
 554 }
 555
 556 /**
 557  * pm_suspend_timer_fn - Timer function for pm_schedule_suspend().
 558  * @data: Device pointer passed by pm_schedule_suspend().
 559  *
 560  * Check if the time is right and execute __pm_request_suspend() in that case.
 561  */
 562 static void pm_suspend_timer_fn(unsigned long data)
 563 {
 564         struct device *dev = (struct device *)data;
 565         unsigned long flags;
 566         unsigned long expires;
 567
 568         spin_lock_irqsave(&dev->power.lock, flags);
 569
 570         expires = dev->power.timer_expires;
 571         /* If 'expire' is after 'jiffies' we've been called too early. */
 572         if (expires > 0 && !time_after(expires, jiffies)) {
 573                 dev->power.timer_expires = 0;
 574                 __pm_request_suspend(dev);
 575         }
 576
 577         spin_unlock_irqrestore(&dev->power.lock, flags);
 578 }
 579
 580 /**
 581  * pm_schedule_suspend - Set up a timer to submit a suspend request in future.
 582  * @dev: Device to suspend.
 583  * @delay: Time to wait before submitting a suspend request, in milliseconds.
 584  */
 585 int pm_schedule_suspend(struct device *dev, unsigned int delay)
 586 {
 587         unsigned long flags;
 588         int retval = 0;
 589
 590         spin_lock_irqsave(&dev->power.lock, flags);
 591
 592         if (dev->power.runtime_error) {
 593                 retval = -EINVAL;
 594                 goto out;
 595         }
 596
 597         if (!delay) {
 598                 retval = __pm_request_suspend(dev);
 599                 goto out;
 600         }
 601
 602         pm_runtime_deactivate_timer(dev);
 603
 604         if (dev->power.request_pending) {
 605                 /*
 606                  * Pending resume requests take precedence over us, but any
 607                  * other pending requests have to be canceled.
 608                  */
 609                 if (dev->power.request == RPM_REQ_RESUME) {
 610                         retval = -EAGAIN;
 611                         goto out;
 612                 }
 613                 dev->power.request = RPM_REQ_NONE;
 614         }
 615
 616         if (dev->power.runtime_status == RPM_SUSPENDED)
 617                 retval = 1;
 618         else if (dev->power.runtime_status == RPM_SUSPENDING)
 619                 retval = -EINPROGRESS;
 620         else if (atomic_read(&dev->power.usage_count) > 0
 621             || dev->power.disable_depth > 0)
 622                 retval = -EAGAIN;
 623         else if (!pm_children_suspended(dev))
 624                 retval = -EBUSY;
 625         if (retval)
 626                 goto out;
 627
 628         dev->power.timer_expires = jiffies + msecs_to_jiffies(delay);
 629         mod_timer(&dev->power.suspend_timer, dev->power.timer_expires);
 630
 631  out:
 632         spin_unlock_irqrestore(&dev->power.lock, flags);
 633
 634         return retval;
 635 }
 636 EXPORT_SYMBOL_GPL(pm_schedule_suspend);
 637
 638 /**
 639  * pm_request_resume - Submit a resume request for given device.
 640  * @dev: Device to resume.
 641  *
 642  * This function must be called under dev->power.lock with interrupts disabled.
 643  */
 644 static int __pm_request_resume(struct device *dev)
 645 {
 646         int retval = 0;
 647
 648         if (dev->power.runtime_error)
 649                 return -EINVAL;
 650
 651         if (dev->power.runtime_status == RPM_ACTIVE)
 652                 retval = 1;
 653         else if (dev->power.runtime_status == RPM_RESUMING)
 654                 retval = -EINPROGRESS;
 655         else if (dev->power.disable_depth > 0)
 656                 retval = -EAGAIN;
 657         if (retval < 0)
 658                 return retval;
 659
 660         pm_runtime_deactivate_timer(dev);
 661
 662         if (dev->power.request_pending) {
 663                 /* If non-resume request is pending, we can overtake it. */
 664                 dev->power.request = retval ? RPM_REQ_NONE : RPM_REQ_RESUME;
 665                 return retval;
 666         } else if (retval) {
 667                 return retval;
 668         }
 669
 670         dev->power.request = RPM_REQ_RESUME;
 671         dev->power.request_pending = true;
 672         queue_work(pm_wq, &dev->power.work);
 673
 674         return retval;
 675 }
 676
 677 /**
 678  * pm_request_resume - Submit a resume request for given device.
 679  * @dev: Device to resume.
 680  */
 681 int pm_request_resume(struct device *dev)
 682 {
 683         unsigned long flags;
 684         int retval;
 685
 686         spin_lock_irqsave(&dev->power.lock, flags);
 687         retval = __pm_request_resume(dev);
 688         spin_unlock_irqrestore(&dev->power.lock, flags);
 689
 690         return retval;
 691 }
 692 EXPORT_SYMBOL_GPL(pm_request_resume);
 693
 694 /**
 695  * __pm_runtime_get - Reference count a device and wake it up, if necessary.
 696  * @dev: Device to handle.
 697  * @sync: If set and the device is suspended, resume it synchronously.
 698  *
 699  * Increment the usage count of the device and if it was zero previously,
 700  * resume it or submit a resume request for it, depending on the value of @sync.
 701  */
 702 int __pm_runtime_get(struct device *dev, bool sync)
 703 {
 704         int retval = 1;
 705
 706         if (atomic_add_return(1, &dev->power.usage_count) == 1)
 707                 retval = sync ? pm_runtime_resume(dev) : pm_request_resume(dev);
 708
 709         return retval;
 710 }
 711 EXPORT_SYMBOL_GPL(__pm_runtime_get);
 712
 713 /**
 714  * __pm_runtime_put - Decrement the device's usage counter and notify its bus.
 715  * @dev: Device to handle.
 716  * @sync: If the device's bus type is to be notified, do that synchronously.
 717  *
 718  * Decrement the usage count of the device and if it reaches zero, carry out a
 719  * synchronous idle notification or submit an idle notification request for it,
 720  * depending on the value of @sync.
 721  */
 722 int __pm_runtime_put(struct device *dev, bool sync)
 723 {
 724         int retval = 0;
 725
 726         if (atomic_dec_and_test(&dev->power.usage_count))
 727                 retval = sync ? pm_runtime_idle(dev) : pm_request_idle(dev);
 728
 729         return retval;
 730 }
 731 EXPORT_SYMBOL_GPL(__pm_runtime_put);
 732
 733 /**
 734  * __pm_runtime_set_status - Set run-time PM status of a device.
 735  * @dev: Device to handle.
 736  * @status: New run-time PM status of the device.
 737  *
 738  * If run-time PM of the device is disabled or its power.runtime_error field is
 739  * different from zero, the status may be changed either to RPM_ACTIVE, or to
 740  * RPM_SUSPENDED, as long as that reflects the actual state of the device.
 741  * However, if the device has a parent and the parent is not active, and the
 742  * parent's power.ignore_children flag is unset, the device's status cannot be
 743  * set to RPM_ACTIVE, so -EBUSY is returned in that case.
 744  *
 745  * If successful, __pm_runtime_set_status() clears the power.runtime_error field
 746  * and the device parent's counter of unsuspended children is modified to
 747  * reflect the new status.  If the new status is RPM_SUSPENDED, an idle
 748  * notification request for the parent is submitted.
 749  */
 750 int __pm_runtime_set_status(struct device *dev, unsigned int status)
 751 {
 752         struct device *parent = dev->parent;
 753         unsigned long flags;
 754         bool notify_parent = false;
 755         int error = 0;
 756
 757         if (status != RPM_ACTIVE && status != RPM_SUSPENDED)
 758                 return -EINVAL;
 759
 760         spin_lock_irqsave(&dev->power.lock, flags);
 761
 762         if (!dev->power.runtime_error && !dev->power.disable_depth) {
 763                 error = -EAGAIN;
 764                 goto out;
 765         }
 766
 767         if (dev->power.runtime_status == status)
 768                 goto out_set;
 769
 770         if (status == RPM_SUSPENDED) {
 771                 /* It always is possible to set the status to 'suspended'. */
 772                 if (parent) {
 773                         atomic_add_unless(&parent->power.child_count, -1, 0);
 774                         notify_parent = !parent->power.ignore_children;
 775                 }
 776                 goto out_set;
 777         }
 778
 779         if (parent) {
 780                 spin_lock_irq(&parent->power.lock);
 781
 782                 /*
 783                  * It is invalid to put an active child under a parent that is
 784                  * not active, has run-time PM enabled and the
 785                  * 'power.ignore_children' flag unset.
 786                  */
 787                 if (!parent->power.disable_depth
 788                     && !parent->power.ignore_children
 789                     && parent->power.runtime_status != RPM_ACTIVE) {
 790                         error = -EBUSY;
 791                 } else {
 792                         if (dev->power.runtime_status == RPM_SUSPENDED)
 793                                 atomic_inc(&parent->power.child_count);
 794                 }
 795
 796                 spin_unlock_irq(&parent->power.lock);
 797
 798                 if (error)
 799                         goto out;
 800         }
 801
 802  out_set:
 803         dev->power.runtime_status = status;
 804         dev->power.runtime_error = 0;
 805  out:
 806         spin_unlock_irqrestore(&dev->power.lock, flags);
 807
 808         if (notify_parent)
 809                 pm_request_idle(parent);
 810
 811         return error;
 812 }
 813 EXPORT_SYMBOL_GPL(__pm_runtime_set_status);
 814
 815 /**
 816  * __pm_runtime_barrier - Cancel pending requests and wait for completions.
 817  * @dev: Device to handle.
 818  *
 819  * Flush all pending requests for the device from pm_wq and wait for all
 820  * run-time PM operations involving the device in progress to complete.
 821  *
 822  * Should be called under dev->power.lock with interrupts disabled.
 823  */
 824 static void __pm_runtime_barrier(struct device *dev)
 825 {
 826         pm_runtime_deactivate_timer(dev);
 827
 828         if (dev->power.request_pending) {
 829                 dev->power.request = RPM_REQ_NONE;
 830                 spin_unlock_irq(&dev->power.lock);
 831
 832                 cancel_work_sync(&dev->power.work);
 833
 834                 spin_lock_irq(&dev->power.lock);
 835                 dev->power.request_pending = false;
 836         }
 837
 838         if (dev->power.runtime_status == RPM_SUSPENDING
 839             || dev->power.runtime_status == RPM_RESUMING
 840             || dev->power.idle_notification) {
 841                 DEFINE_WAIT(wait);
 842
 843                 /* Suspend, wake-up or idle notification in progress. */
 844                 for (;;) {
 845                         prepare_to_wait(&dev->power.wait_queue, &wait,
 846                                         TASK_UNINTERRUPTIBLE);
 847                         if (dev->power.runtime_status != RPM_SUSPENDING
 848                             && dev->power.runtime_status != RPM_RESUMING
 849                             && !dev->power.idle_notification)
 850                                 break;
 851                         spin_unlock_irq(&dev->power.lock);
 852
 853                         schedule();
 854
 855                         spin_lock_irq(&dev->power.lock);
 856                 }
 857                 finish_wait(&dev->power.wait_queue, &wait);
 858         }
 859 }
 860
 861 /**
 862  * pm_runtime_barrier - Flush pending requests and wait for completions.
 863  * @dev: Device to handle.
 864  *
 865  * Prevent the device from being suspended by incrementing its usage counter and
 866  * if there's a pending resume request for the device, wake the device up.
 867  * Next, make sure that all pending requests for the device have been flushed
 868  * from pm_wq and wait for all run-time PM operations involving the device in
 869  * progress to complete.
 870  *
 871  * Return value:
 872  * 1, if there was a resume request pending and the device had to be woken up,
 873  * 0, otherwise
 874  */
 875 int pm_runtime_barrier(struct device *dev)
 876 {
 877         int retval = 0;
 878
 879         pm_runtime_get_noresume(dev);
 880         spin_lock_irq(&dev->power.lock);
 881
 882         if (dev->power.request_pending
 883             && dev->power.request == RPM_REQ_RESUME) {
 884                 __pm_runtime_resume(dev, false);
 885                 retval = 1;
 886         }
 887
 888         __pm_runtime_barrier(dev);
 889
 890         spin_unlock_irq(&dev->power.lock);
 891         pm_runtime_put_noidle(dev);
 892
 893         return retval;
 894 }
 895 EXPORT_SYMBOL_GPL(pm_runtime_barrier);
 896
 897 /**
 898  * __pm_runtime_disable - Disable run-time PM of a device.
 899  * @dev: Device to handle.
 900  * @check_resume: If set, check if there's a resume request for the device.
 901  *
 902  * Increment power.disable_depth for the device and if was zero previously,
 903  * cancel all pending run-time PM requests for the device and wait for all
 904  * operations in progress to complete.  The device can be either active or
 905  * suspended after its run-time PM has been disabled.
 906  *
 907  * If @check_resume is set and there's a resume request pending when
 908  * __pm_runtime_disable() is called and power.disable_depth is zero, the
 909  * function will wake up the device before disabling its run-time PM.
 910  */
 911 void __pm_runtime_disable(struct device *dev, bool check_resume)
 912 {
 913         spin_lock_irq(&dev->power.lock);
 914
 915         if (dev->power.disable_depth > 0) {
 916                 dev->power.disable_depth++;
 917                 goto out;
 918         }
 919
 920         /*
 921          * Wake up the device if there's a resume request pending, because that
 922          * means there probably is some I/O to process and disabling run-time PM
 923          * shouldn't prevent the device from processing the I/O.
 924          */
 925         if (check_resume && dev->power.request_pending
 926             && dev->power.request == RPM_REQ_RESUME) {
 927                 /*
 928                  * Prevent suspends and idle notifications from being carried
 929                  * out after we have woken up the device.
 930                  */
 931                 pm_runtime_get_noresume(dev);
 932
 933                 __pm_runtime_resume(dev, false);
 934
 935                 pm_runtime_put_noidle(dev);
 936         }
 937
 938         if (!dev->power.disable_depth++)
 939                 __pm_runtime_barrier(dev);
 940
 941  out:
 942         spin_unlock_irq(&dev->power.lock);
 943 }
 944 EXPORT_SYMBOL_GPL(__pm_runtime_disable);
 945
 946 /**
 947  * pm_runtime_enable - Enable run-time PM of a device.
 948  * @dev: Device to handle.
 949  */
 950 void pm_runtime_enable(struct device *dev)
 951 {
 952         unsigned long flags;
 953
 954         spin_lock_irqsave(&dev->power.lock, flags);
 955
 956         if (dev->power.disable_depth > 0)
 957                 dev->power.disable_depth--;
 958         else
 959                 dev_warn(dev, "Unbalanced %s!\n", __func__);
 960
 961         spin_unlock_irqrestore(&dev->power.lock, flags);
 962 }
 963 EXPORT_SYMBOL_GPL(pm_runtime_enable);
 964
 965 /**
 966  * pm_runtime_init - Initialize run-time PM fields in given device object.
 967  * @dev: Device object to initialize.
 968  */
 969 void pm_runtime_init(struct device *dev)
 970 {
 971         spin_lock_init(&dev->power.lock);
 972
 973         dev->power.runtime_status = RPM_SUSPENDED;
 974         dev->power.idle_notification = false;
 975
 976         dev->power.disable_depth = 1;
 977         atomic_set(&dev->power.usage_count, 0);
 978
 979         dev->power.runtime_error = 0;
 980
 981         atomic_set(&dev->power.child_count, 0);
 982         pm_suspend_ignore_children(dev, false);
 983
 984         dev->power.request_pending = false;
 985         dev->power.request = RPM_REQ_NONE;
 986         dev->power.deferred_resume = false;
 987         INIT_WORK(&dev->power.work, pm_runtime_work);
 988
 989         dev->power.timer_expires = 0;
 990         setup_timer(&dev->power.suspend_timer, pm_suspend_timer_fn,
 991                         (unsigned long)dev);
 992
 993         init_waitqueue_head(&dev->power.wait_queue);
 994 }
 995
 996 /**
 997  * pm_runtime_remove - Prepare for removing a device from device hierarchy.
 998  * @dev: Device object being removed from device hierarchy.
 999  */
1000 void pm_runtime_remove(struct device *dev)
1001 {
1002         __pm_runtime_disable(dev, false);
1003
1004         /* Change the status back to 'suspended' to match the initial status. */
1005         if (dev->power.runtime_status == RPM_ACTIVE)
1006                 pm_runtime_set_suspended(dev);
1007 }