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