drivers/base/power/runtime.c

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