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/mm.h>
  11 #include <linux/export.h>
  12 #include <linux/pm_runtime.h>
  13 #include <linux/pm_wakeirq.h>
  14 #include <trace/events/rpm.h>
  15
  16 #include "../base.h"
  17 #include "power.h"
  18
  19 typedef int (*pm_callback_t)(struct device *);
  20
  21 static pm_callback_t __rpm_get_callback(struct device *dev, size_t cb_offset)
  22 {
  23         pm_callback_t cb;
  24         const struct dev_pm_ops *ops;
  25
  26         if (dev->pm_domain)
  27                 ops = &dev->pm_domain->ops;
  28         else if (dev->type && dev->type->pm)
  29                 ops = dev->type->pm;
  30         else if (dev->class && dev->class->pm)
  31                 ops = dev->class->pm;
  32         else if (dev->bus && dev->bus->pm)
  33                 ops = dev->bus->pm;
  34         else
  35                 ops = NULL;
  36
  37         if (ops)
  38                 cb = *(pm_callback_t *)((void *)ops + cb_offset);
  39         else
  40                 cb = NULL;
  41
  42         if (!cb && dev->driver && dev->driver->pm)
  43                 cb = *(pm_callback_t *)((void *)dev->driver->pm + cb_offset);
  44
  45         return cb;
  46 }
  47
  48 #define RPM_GET_CALLBACK(dev, callback) \
  49                 __rpm_get_callback(dev, offsetof(struct dev_pm_ops, callback))
  50
  51 static int rpm_resume(struct device *dev, int rpmflags);
  52 static int rpm_suspend(struct device *dev, int rpmflags);
  53
  54 /**
  55  * update_pm_runtime_accounting - Update the time accounting of power states
  56  * @dev: Device to update the accounting for
  57  *
  58  * In order to be able to have time accounting of the various power states
  59  * (as used by programs such as PowerTOP to show the effectiveness of runtime
  60  * PM), we need to track the time spent in each state.
  61  * update_pm_runtime_accounting must be called each time before the
  62  * runtime_status field is updated, to account the time in the old state
  63  * correctly.
  64  */
  65 void update_pm_runtime_accounting(struct device *dev)
  66 {
  67         unsigned long now = jiffies;
  68         unsigned long delta;
  69
  70         delta = now - dev->power.accounting_timestamp;
  71
  72         dev->power.accounting_timestamp = now;
  73
  74         if (dev->power.disable_depth > 0)
  75                 return;
  76
  77         if (dev->power.runtime_status == RPM_SUSPENDED)
  78                 dev->power.suspended_jiffies += delta;
  79         else
  80                 dev->power.active_jiffies += delta;
  81 }
  82
  83 static void __update_runtime_status(struct device *dev, enum rpm_status status)
  84 {
  85         update_pm_runtime_accounting(dev);
  86         dev->power.runtime_status = status;
  87 }
  88
  89 /**
  90  * pm_runtime_deactivate_timer - Deactivate given device's suspend timer.
  91  * @dev: Device to handle.
  92  */
  93 static void pm_runtime_deactivate_timer(struct device *dev)
  94 {
  95         if (dev->power.timer_expires > 0) {
  96                 del_timer(&dev->power.suspend_timer);
  97                 dev->power.timer_expires = 0;
  98         }
  99 }
 100
 101 /**
 102  * pm_runtime_cancel_pending - Deactivate suspend timer and cancel requests.
 103  * @dev: Device to handle.
 104  */
 105 static void pm_runtime_cancel_pending(struct device *dev)
 106 {
 107         pm_runtime_deactivate_timer(dev);
 108         /*
 109          * In case there's a request pending, make sure its work function will
 110          * return without doing anything.
 111          */
 112         dev->power.request = RPM_REQ_NONE;
 113 }
 114
 115 /*
 116  * pm_runtime_autosuspend_expiration - Get a device's autosuspend-delay expiration time.
 117  * @dev: Device to handle.
 118  *
 119  * Compute the autosuspend-delay expiration time based on the device's
 120  * power.last_busy time.  If the delay has already expired or is disabled
 121  * (negative) or the power.use_autosuspend flag isn't set, return 0.
 122  * Otherwise return the expiration time in jiffies (adjusted to be nonzero).
 123  *
 124  * This function may be called either with or without dev->power.lock held.
 125  * Either way it can be racy, since power.last_busy may be updated at any time.
 126  */
 127 unsigned long pm_runtime_autosuspend_expiration(struct device *dev)
 128 {
 129         int autosuspend_delay;
 130         long elapsed;
 131         unsigned long last_busy;
 132         unsigned long expires = 0;
 133
 134         if (!dev->power.use_autosuspend)
 135                 goto out;
 136
 137         autosuspend_delay = READ_ONCE(dev->power.autosuspend_delay);
 138         if (autosuspend_delay < 0)
 139                 goto out;
 140
 141         last_busy = READ_ONCE(dev->power.last_busy);
 142         elapsed = jiffies - last_busy;
 143         if (elapsed < 0)
 144                 goto out;       /* jiffies has wrapped around. */
 145
 146         /*
 147          * If the autosuspend_delay is >= 1 second, align the timer by rounding
 148          * up to the nearest second.
 149          */
 150         expires = last_busy + msecs_to_jiffies(autosuspend_delay);
 151         if (autosuspend_delay >= 1000)
 152                 expires = round_jiffies(expires);
 153         expires += !expires;
 154         if (elapsed >= expires - last_busy)
 155                 expires = 0;    /* Already expired. */
 156
 157  out:
 158         return expires;
 159 }
 160 EXPORT_SYMBOL_GPL(pm_runtime_autosuspend_expiration);
 161
 162 static int dev_memalloc_noio(struct device *dev, void *data)
 163 {
 164         return dev->power.memalloc_noio;
 165 }
 166
 167 /*
 168  * pm_runtime_set_memalloc_noio - Set a device's memalloc_noio flag.
 169  * @dev: Device to handle.
 170  * @enable: True for setting the flag and False for clearing the flag.
 171  *
 172  * Set the flag for all devices in the path from the device to the
 173  * root device in the device tree if @enable is true, otherwise clear
 174  * the flag for devices in the path whose siblings don't set the flag.
 175  *
 176  * The function should only be called by block device, or network
 177  * device driver for solving the deadlock problem during runtime
 178  * resume/suspend:
 179  *
 180  *     If memory allocation with GFP_KERNEL is called inside runtime
 181  *     resume/suspend callback of any one of its ancestors(or the
 182  *     block device itself), the deadlock may be triggered inside the
 183  *     memory allocation since it might not complete until the block
 184  *     device becomes active and the involed page I/O finishes. The
 185  *     situation is pointed out first by Alan Stern. Network device
 186  *     are involved in iSCSI kind of situation.
 187  *
 188  * The lock of dev_hotplug_mutex is held in the function for handling
 189  * hotplug race because pm_runtime_set_memalloc_noio() may be called
 190  * in async probe().
 191  *
 192  * The function should be called between device_add() and device_del()
 193  * on the affected device(block/network device).
 194  */
 195 void pm_runtime_set_memalloc_noio(struct device *dev, bool enable)
 196 {
 197         static DEFINE_MUTEX(dev_hotplug_mutex);
 198
 199         mutex_lock(&dev_hotplug_mutex);
 200         for (;;) {
 201                 bool enabled;
 202
 203                 /* hold power lock since bitfield is not SMP-safe. */
 204                 spin_lock_irq(&dev->power.lock);
 205                 enabled = dev->power.memalloc_noio;
 206                 dev->power.memalloc_noio = enable;
 207                 spin_unlock_irq(&dev->power.lock);
 208
 209                 /*
 210                  * not need to enable ancestors any more if the device
 211                  * has been enabled.
 212                  */
 213                 if (enabled && enable)
 214                         break;
 215
 216                 dev = dev->parent;
 217
 218                 /*
 219                  * clear flag of the parent device only if all the
 220                  * children don't set the flag because ancestor's
 221                  * flag was set by any one of the descendants.
 222                  */
 223                 if (!dev || (!enable &&
 224                              device_for_each_child(dev, NULL,
 225                                                    dev_memalloc_noio)))
 226                         break;
 227         }
 228         mutex_unlock(&dev_hotplug_mutex);
 229 }
 230 EXPORT_SYMBOL_GPL(pm_runtime_set_memalloc_noio);
 231
 232 /**
 233  * rpm_check_suspend_allowed - Test whether a device may be suspended.
 234  * @dev: Device to test.
 235  */
 236 static int rpm_check_suspend_allowed(struct device *dev)
 237 {
 238         int retval = 0;
 239
 240         if (dev->power.runtime_error)
 241                 retval = -EINVAL;
 242         else if (dev->power.disable_depth > 0)
 243                 retval = -EACCES;
 244         else if (atomic_read(&dev->power.usage_count) > 0)
 245                 retval = -EAGAIN;
 246         else if (!dev->power.ignore_children &&
 247                         atomic_read(&dev->power.child_count))
 248                 retval = -EBUSY;
 249
 250         /* Pending resume requests take precedence over suspends. */
 251         else if ((dev->power.deferred_resume
 252                         && dev->power.runtime_status == RPM_SUSPENDING)
 253             || (dev->power.request_pending
 254                         && dev->power.request == RPM_REQ_RESUME))
 255                 retval = -EAGAIN;
 256         else if (__dev_pm_qos_read_value(dev) == 0)
 257                 retval = -EPERM;
 258         else if (dev->power.runtime_status == RPM_SUSPENDED)
 259                 retval = 1;
 260
 261         return retval;
 262 }
 263
 264 static int rpm_get_suppliers(struct device *dev)
 265 {
 266         struct device_link *link;
 267
 268         list_for_each_entry_rcu(link, &dev->links.suppliers, c_node) {
 269                 int retval;
 270
 271                 if (!(link->flags & DL_FLAG_PM_RUNTIME))
 272                         continue;
 273
 274                 if (READ_ONCE(link->status) == DL_STATE_SUPPLIER_UNBIND ||
 275                     link->rpm_active)
 276                         continue;
 277
 278                 retval = pm_runtime_get_sync(link->supplier);
 279                 /* Ignore suppliers with disabled runtime PM. */
 280                 if (retval < 0 && retval != -EACCES) {
 281                         pm_runtime_put_noidle(link->supplier);
 282                         return retval;
 283                 }
 284                 link->rpm_active = true;
 285         }
 286         return 0;
 287 }
 288
 289 static void rpm_put_suppliers(struct device *dev)
 290 {
 291         struct device_link *link;
 292
 293         list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
 294                 if (link->rpm_active &&
 295                     READ_ONCE(link->status) != DL_STATE_SUPPLIER_UNBIND) {
 296                         pm_runtime_put(link->supplier);
 297                         link->rpm_active = false;
 298                 }
 299 }
 300
 301 /**
 302  * __rpm_callback - Run a given runtime PM callback for a given device.
 303  * @cb: Runtime PM callback to run.
 304  * @dev: Device to run the callback for.
 305  */
 306 static int __rpm_callback(int (*cb)(struct device *), struct device *dev)
 307         __releases(&dev->power.lock) __acquires(&dev->power.lock)
 308 {
 309         int retval, idx;
 310         bool use_links = dev->power.links_count > 0;
 311
 312         if (dev->power.irq_safe) {
 313                 spin_unlock(&dev->power.lock);
 314         } else {
 315                 spin_unlock_irq(&dev->power.lock);
 316
 317                 /*
 318                  * Resume suppliers if necessary.
 319                  *
 320                  * The device's runtime PM status cannot change until this
 321                  * routine returns, so it is safe to read the status outside of
 322                  * the lock.
 323                  */
 324                 if (use_links && dev->power.runtime_status == RPM_RESUMING) {
 325                         idx = device_links_read_lock();
 326
 327                         retval = rpm_get_suppliers(dev);
 328                         if (retval)
 329                                 goto fail;
 330
 331                         device_links_read_unlock(idx);
 332                 }
 333         }
 334
 335         retval = cb(dev);
 336
 337         if (dev->power.irq_safe) {
 338                 spin_lock(&dev->power.lock);
 339         } else {
 340                 /*
 341                  * If the device is suspending and the callback has returned
 342                  * success, drop the usage counters of the suppliers that have
 343                  * been reference counted on its resume.
 344                  *
 345                  * Do that if resume fails too.
 346                  */
 347                 if (use_links
 348                     && ((dev->power.runtime_status == RPM_SUSPENDING && !retval)
 349                     || (dev->power.runtime_status == RPM_RESUMING && retval))) {
 350                         idx = device_links_read_lock();
 351
 352  fail:
 353                         rpm_put_suppliers(dev);
 354
 355                         device_links_read_unlock(idx);
 356                 }
 357
 358                 spin_lock_irq(&dev->power.lock);
 359         }
 360
 361         return retval;
 362 }
 363
 364 /**
 365  * rpm_idle - Notify device bus type if the device can be suspended.
 366  * @dev: Device to notify the bus type about.
 367  * @rpmflags: Flag bits.
 368  *
 369  * Check if the device's runtime PM status allows it to be suspended.  If
 370  * another idle notification has been started earlier, return immediately.  If
 371  * the RPM_ASYNC flag is set then queue an idle-notification request; otherwise
 372  * run the ->runtime_idle() callback directly. If the ->runtime_idle callback
 373  * doesn't exist or if it returns 0, call rpm_suspend with the RPM_AUTO flag.
 374  *
 375  * This function must be called under dev->power.lock with interrupts disabled.
 376  */
 377 static int rpm_idle(struct device *dev, int rpmflags)
 378 {
 379         int (*callback)(struct device *);
 380         int retval;
 381
 382         trace_rpm_idle_rcuidle(dev, rpmflags);
 383         retval = rpm_check_suspend_allowed(dev);
 384         if (retval < 0)
 385                 ;       /* Conditions are wrong. */
 386
 387         /* Idle notifications are allowed only in the RPM_ACTIVE state. */
 388         else if (dev->power.runtime_status != RPM_ACTIVE)
 389                 retval = -EAGAIN;
 390
 391         /*
 392          * Any pending request other than an idle notification takes
 393          * precedence over us, except that the timer may be running.
 394          */
 395         else if (dev->power.request_pending &&
 396             dev->power.request > RPM_REQ_IDLE)
 397                 retval = -EAGAIN;
 398
 399         /* Act as though RPM_NOWAIT is always set. */
 400         else if (dev->power.idle_notification)
 401                 retval = -EINPROGRESS;
 402         if (retval)
 403                 goto out;
 404
 405         /* Pending requests need to be canceled. */
 406         dev->power.request = RPM_REQ_NONE;
 407
 408         if (dev->power.no_callbacks)
 409                 goto out;
 410
 411         /* Carry out an asynchronous or a synchronous idle notification. */
 412         if (rpmflags & RPM_ASYNC) {
 413                 dev->power.request = RPM_REQ_IDLE;
 414                 if (!dev->power.request_pending) {
 415                         dev->power.request_pending = true;
 416                         queue_work(pm_wq, &dev->power.work);
 417                 }
 418                 trace_rpm_return_int_rcuidle(dev, _THIS_IP_, 0);
 419                 return 0;
 420         }
 421
 422         dev->power.idle_notification = true;
 423
 424         callback = RPM_GET_CALLBACK(dev, runtime_idle);
 425
 426         if (callback)
 427                 retval = __rpm_callback(callback, dev);
 428
 429         dev->power.idle_notification = false;
 430         wake_up_all(&dev->power.wait_queue);
 431
 432  out:
 433         trace_rpm_return_int_rcuidle(dev, _THIS_IP_, retval);
 434         return retval ? retval : rpm_suspend(dev, rpmflags | RPM_AUTO);
 435 }
 436
 437 /**
 438  * rpm_callback - Run a given runtime PM callback for a given device.
 439  * @cb: Runtime PM callback to run.
 440  * @dev: Device to run the callback for.
 441  */
 442 static int rpm_callback(int (*cb)(struct device *), struct device *dev)
 443 {
 444         int retval;
 445
 446         if (!cb)
 447                 return -ENOSYS;
 448
 449         if (dev->power.memalloc_noio) {
 450                 unsigned int noio_flag;
 451
 452                 /*
 453                  * Deadlock might be caused if memory allocation with
 454                  * GFP_KERNEL happens inside runtime_suspend and
 455                  * runtime_resume callbacks of one block device's
 456                  * ancestor or the block device itself. Network
 457                  * device might be thought as part of iSCSI block
 458                  * device, so network device and its ancestor should
 459                  * be marked as memalloc_noio too.
 460                  */
 461                 noio_flag = memalloc_noio_save();
 462                 retval = __rpm_callback(cb, dev);
 463                 memalloc_noio_restore(noio_flag);
 464         } else {
 465                 retval = __rpm_callback(cb, dev);
 466         }
 467
 468         dev->power.runtime_error = retval;
 469         return retval != -EACCES ? retval : -EIO;
 470 }
 471
 472 /**
 473  * rpm_suspend - Carry out runtime suspend of given device.
 474  * @dev: Device to suspend.
 475  * @rpmflags: Flag bits.
 476  *
 477  * Check if the device's runtime PM status allows it to be suspended.
 478  * Cancel a pending idle notification, autosuspend or suspend. If
 479  * another suspend has been started earlier, either return immediately
 480  * or wait for it to finish, depending on the RPM_NOWAIT and RPM_ASYNC
 481  * flags. If the RPM_ASYNC flag is set then queue a suspend request;
 482  * otherwise run the ->runtime_suspend() callback directly. When
 483  * ->runtime_suspend succeeded, if a deferred resume was requested while
 484  * the callback was running then carry it out, otherwise send an idle
 485  * notification for its parent (if the suspend succeeded and both
 486  * ignore_children of parent->power and irq_safe of dev->power are not set).
 487  * If ->runtime_suspend failed with -EAGAIN or -EBUSY, and if the RPM_AUTO
 488  * flag is set and the next autosuspend-delay expiration time is in the
 489  * future, schedule another autosuspend attempt.
 490  *
 491  * This function must be called under dev->power.lock with interrupts disabled.
 492  */
 493 static int rpm_suspend(struct device *dev, int rpmflags)
 494         __releases(&dev->power.lock) __acquires(&dev->power.lock)
 495 {
 496         int (*callback)(struct device *);
 497         struct device *parent = NULL;
 498         int retval;
 499
 500         trace_rpm_suspend_rcuidle(dev, rpmflags);
 501
 502  repeat:
 503         retval = rpm_check_suspend_allowed(dev);
 504
 505         if (retval < 0)
 506                 ;       /* Conditions are wrong. */
 507
 508         /* Synchronous suspends are not allowed in the RPM_RESUMING state. */
 509         else if (dev->power.runtime_status == RPM_RESUMING &&
 510             !(rpmflags & RPM_ASYNC))
 511                 retval = -EAGAIN;
 512         if (retval)
 513                 goto out;
 514
 515         /* If the autosuspend_delay time hasn't expired yet, reschedule. */
 516         if ((rpmflags & RPM_AUTO)
 517             && dev->power.runtime_status != RPM_SUSPENDING) {
 518                 unsigned long expires = pm_runtime_autosuspend_expiration(dev);
 519
 520                 if (expires != 0) {
 521                         /* Pending requests need to be canceled. */
 522                         dev->power.request = RPM_REQ_NONE;
 523
 524                         /*
 525                          * Optimization: If the timer is already running and is
 526                          * set to expire at or before the autosuspend delay,
 527                          * avoid the overhead of resetting it.  Just let it
 528                          * expire; pm_suspend_timer_fn() will take care of the
 529                          * rest.
 530                          */
 531                         if (!(dev->power.timer_expires && time_before_eq(
 532                             dev->power.timer_expires, expires))) {
 533                                 dev->power.timer_expires = expires;
 534                                 mod_timer(&dev->power.suspend_timer, expires);
 535                         }
 536                         dev->power.timer_autosuspends = 1;
 537                         goto out;
 538                 }
 539         }
 540
 541         /* Other scheduled or pending requests need to be canceled. */
 542         pm_runtime_cancel_pending(dev);
 543
 544         if (dev->power.runtime_status == RPM_SUSPENDING) {
 545                 DEFINE_WAIT(wait);
 546
 547                 if (rpmflags & (RPM_ASYNC | RPM_NOWAIT)) {
 548                         retval = -EINPROGRESS;
 549                         goto out;
 550                 }
 551
 552                 if (dev->power.irq_safe) {
 553                         spin_unlock(&dev->power.lock);
 554
 555                         cpu_relax();
 556
 557                         spin_lock(&dev->power.lock);
 558                         goto repeat;
 559                 }
 560
 561                 /* Wait for the other suspend running in parallel with us. */
 562                 for (;;) {
 563                         prepare_to_wait(&dev->power.wait_queue, &wait,
 564                                         TASK_UNINTERRUPTIBLE);
 565                         if (dev->power.runtime_status != RPM_SUSPENDING)
 566                                 break;
 567
 568                         spin_unlock_irq(&dev->power.lock);
 569
 570                         schedule();
 571
 572                         spin_lock_irq(&dev->power.lock);
 573                 }
 574                 finish_wait(&dev->power.wait_queue, &wait);
 575                 goto repeat;
 576         }
 577
 578         if (dev->power.no_callbacks)
 579                 goto no_callback;       /* Assume success. */
 580
 581         /* Carry out an asynchronous or a synchronous suspend. */
 582         if (rpmflags & RPM_ASYNC) {
 583                 dev->power.request = (rpmflags & RPM_AUTO) ?
 584                     RPM_REQ_AUTOSUSPEND : RPM_REQ_SUSPEND;
 585                 if (!dev->power.request_pending) {
 586                         dev->power.request_pending = true;
 587                         queue_work(pm_wq, &dev->power.work);
 588                 }
 589                 goto out;
 590         }
 591
 592         __update_runtime_status(dev, RPM_SUSPENDING);
 593
 594         callback = RPM_GET_CALLBACK(dev, runtime_suspend);
 595
 596         dev_pm_enable_wake_irq_check(dev, true);
 597         retval = rpm_callback(callback, dev);
 598         if (retval)
 599                 goto fail;
 600
 601  no_callback:
 602         __update_runtime_status(dev, RPM_SUSPENDED);
 603         pm_runtime_deactivate_timer(dev);
 604
 605         if (dev->parent) {
 606                 parent = dev->parent;
 607                 atomic_add_unless(&parent->power.child_count, -1, 0);
 608         }
 609         wake_up_all(&dev->power.wait_queue);
 610
 611         if (dev->power.deferred_resume) {
 612                 dev->power.deferred_resume = false;
 613                 rpm_resume(dev, 0);
 614                 retval = -EAGAIN;
 615                 goto out;
 616         }
 617
 618         /* Maybe the parent is now able to suspend. */
 619         if (parent && !parent->power.ignore_children && !dev->power.irq_safe) {
 620                 spin_unlock(&dev->power.lock);
 621
 622                 spin_lock(&parent->power.lock);
 623                 rpm_idle(parent, RPM_ASYNC);
 624                 spin_unlock(&parent->power.lock);
 625
 626                 spin_lock(&dev->power.lock);
 627         }
 628
 629  out:
 630         trace_rpm_return_int_rcuidle(dev, _THIS_IP_, retval);
 631
 632         return retval;
 633
 634  fail:
 635         dev_pm_disable_wake_irq_check(dev);
 636         __update_runtime_status(dev, RPM_ACTIVE);
 637         dev->power.deferred_resume = false;
 638         wake_up_all(&dev->power.wait_queue);
 639
 640         if (retval == -EAGAIN || retval == -EBUSY) {
 641                 dev->power.runtime_error = 0;
 642
 643                 /*
 644                  * If the callback routine failed an autosuspend, and
 645                  * if the last_busy time has been updated so that there
 646                  * is a new autosuspend expiration time, automatically
 647                  * reschedule another autosuspend.
 648                  */
 649                 if ((rpmflags & RPM_AUTO) &&
 650                     pm_runtime_autosuspend_expiration(dev) != 0)
 651                         goto repeat;
 652         } else {
 653                 pm_runtime_cancel_pending(dev);
 654         }
 655         goto out;
 656 }
 657
 658 /**
 659  * rpm_resume - Carry out runtime resume of given device.
 660  * @dev: Device to resume.
 661  * @rpmflags: Flag bits.
 662  *
 663  * Check if the device's runtime PM status allows it to be resumed.  Cancel
 664  * any scheduled or pending requests.  If another resume has been started
 665  * earlier, either return immediately or wait for it to finish, depending on the
 666  * RPM_NOWAIT and RPM_ASYNC flags.  Similarly, if there's a suspend running in
 667  * parallel with this function, either tell the other process to resume after
 668  * suspending (deferred_resume) or wait for it to finish.  If the RPM_ASYNC
 669  * flag is set then queue a resume request; otherwise run the
 670  * ->runtime_resume() callback directly.  Queue an idle notification for the
 671  * device if the resume succeeded.
 672  *
 673  * This function must be called under dev->power.lock with interrupts disabled.
 674  */
 675 static int rpm_resume(struct device *dev, int rpmflags)
 676         __releases(&dev->power.lock) __acquires(&dev->power.lock)
 677 {
 678         int (*callback)(struct device *);
 679         struct device *parent = NULL;
 680         int retval = 0;
 681
 682         trace_rpm_resume_rcuidle(dev, rpmflags);
 683
 684  repeat:
 685         if (dev->power.runtime_error)
 686                 retval = -EINVAL;
 687         else if (dev->power.disable_depth == 1 && dev->power.is_suspended
 688             && dev->power.runtime_status == RPM_ACTIVE)
 689                 retval = 1;
 690         else if (dev->power.disable_depth > 0)
 691                 retval = -EACCES;
 692         if (retval)
 693                 goto out;
 694
 695         /*
 696          * Other scheduled or pending requests need to be canceled.  Small
 697          * optimization: If an autosuspend timer is running, leave it running
 698          * rather than cancelling it now only to restart it again in the near
 699          * future.
 700          */
 701         dev->power.request = RPM_REQ_NONE;
 702         if (!dev->power.timer_autosuspends)
 703                 pm_runtime_deactivate_timer(dev);
 704
 705         if (dev->power.runtime_status == RPM_ACTIVE) {
 706                 retval = 1;
 707                 goto out;
 708         }
 709
 710         if (dev->power.runtime_status == RPM_RESUMING
 711             || dev->power.runtime_status == RPM_SUSPENDING) {
 712                 DEFINE_WAIT(wait);
 713
 714                 if (rpmflags & (RPM_ASYNC | RPM_NOWAIT)) {
 715                         if (dev->power.runtime_status == RPM_SUSPENDING)
 716                                 dev->power.deferred_resume = true;
 717                         else
 718                                 retval = -EINPROGRESS;
 719                         goto out;
 720                 }
 721
 722                 if (dev->power.irq_safe) {
 723                         spin_unlock(&dev->power.lock);
 724
 725                         cpu_relax();
 726
 727                         spin_lock(&dev->power.lock);
 728                         goto repeat;
 729                 }
 730
 731                 /* Wait for the operation carried out in parallel with us. */
 732                 for (;;) {
 733                         prepare_to_wait(&dev->power.wait_queue, &wait,
 734                                         TASK_UNINTERRUPTIBLE);
 735                         if (dev->power.runtime_status != RPM_RESUMING
 736                             && dev->power.runtime_status != RPM_SUSPENDING)
 737                                 break;
 738
 739                         spin_unlock_irq(&dev->power.lock);
 740
 741                         schedule();
 742
 743                         spin_lock_irq(&dev->power.lock);
 744                 }
 745                 finish_wait(&dev->power.wait_queue, &wait);
 746                 goto repeat;
 747         }
 748
 749         /*
 750          * See if we can skip waking up the parent.  This is safe only if
 751          * power.no_callbacks is set, because otherwise we don't know whether
 752          * the resume will actually succeed.
 753          */
 754         if (dev->power.no_callbacks && !parent && dev->parent) {
 755                 spin_lock_nested(&dev->parent->power.lock, SINGLE_DEPTH_NESTING);
 756                 if (dev->parent->power.disable_depth > 0
 757                     || dev->parent->power.ignore_children
 758                     || dev->parent->power.runtime_status == RPM_ACTIVE) {
 759                         atomic_inc(&dev->parent->power.child_count);
 760                         spin_unlock(&dev->parent->power.lock);
 761                         retval = 1;
 762                         goto no_callback;       /* Assume success. */
 763                 }
 764                 spin_unlock(&dev->parent->power.lock);
 765         }
 766
 767         /* Carry out an asynchronous or a synchronous resume. */
 768         if (rpmflags & RPM_ASYNC) {
 769                 dev->power.request = RPM_REQ_RESUME;
 770                 if (!dev->power.request_pending) {
 771                         dev->power.request_pending = true;
 772                         queue_work(pm_wq, &dev->power.work);
 773                 }
 774                 retval = 0;
 775                 goto out;
 776         }
 777
 778         if (!parent && dev->parent) {
 779                 /*
 780                  * Increment the parent's usage counter and resume it if
 781                  * necessary.  Not needed if dev is irq-safe; then the
 782                  * parent is permanently resumed.
 783                  */
 784                 parent = dev->parent;
 785                 if (dev->power.irq_safe)
 786                         goto skip_parent;
 787                 spin_unlock(&dev->power.lock);
 788
 789                 pm_runtime_get_noresume(parent);
 790
 791                 spin_lock(&parent->power.lock);
 792                 /*
 793                  * Resume the parent if it has runtime PM enabled and not been
 794                  * set to ignore its children.
 795                  */
 796                 if (!parent->power.disable_depth
 797                     && !parent->power.ignore_children) {
 798                         rpm_resume(parent, 0);
 799                         if (parent->power.runtime_status != RPM_ACTIVE)
 800                                 retval = -EBUSY;
 801                 }
 802                 spin_unlock(&parent->power.lock);
 803
 804                 spin_lock(&dev->power.lock);
 805                 if (retval)
 806                         goto out;
 807                 goto repeat;
 808         }
 809  skip_parent:
 810
 811         if (dev->power.no_callbacks)
 812                 goto no_callback;       /* Assume success. */
 813
 814         __update_runtime_status(dev, RPM_RESUMING);
 815
 816         callback = RPM_GET_CALLBACK(dev, runtime_resume);
 817
 818         dev_pm_disable_wake_irq_check(dev);
 819         retval = rpm_callback(callback, dev);
 820         if (retval) {
 821                 __update_runtime_status(dev, RPM_SUSPENDED);
 822                 pm_runtime_cancel_pending(dev);
 823                 dev_pm_enable_wake_irq_check(dev, false);
 824         } else {
 825  no_callback:
 826                 __update_runtime_status(dev, RPM_ACTIVE);
 827                 pm_runtime_mark_last_busy(dev);
 828                 if (parent)
 829                         atomic_inc(&parent->power.child_count);
 830         }
 831         wake_up_all(&dev->power.wait_queue);
 832
 833         if (retval >= 0)
 834                 rpm_idle(dev, RPM_ASYNC);
 835
 836  out:
 837         if (parent && !dev->power.irq_safe) {
 838                 spin_unlock_irq(&dev->power.lock);
 839
 840                 pm_runtime_put(parent);
 841
 842                 spin_lock_irq(&dev->power.lock);
 843         }
 844
 845         trace_rpm_return_int_rcuidle(dev, _THIS_IP_, retval);
 846
 847         return retval;
 848 }
 849
 850 /**
 851  * pm_runtime_work - Universal runtime PM work function.
 852  * @work: Work structure used for scheduling the execution of this function.
 853  *
 854  * Use @work to get the device object the work is to be done for, determine what
 855  * is to be done and execute the appropriate runtime PM function.
 856  */
 857 static void pm_runtime_work(struct work_struct *work)
 858 {
 859         struct device *dev = container_of(work, struct device, power.work);
 860         enum rpm_request req;
 861
 862         spin_lock_irq(&dev->power.lock);
 863
 864         if (!dev->power.request_pending)
 865                 goto out;
 866
 867         req = dev->power.request;
 868         dev->power.request = RPM_REQ_NONE;
 869         dev->power.request_pending = false;
 870
 871         switch (req) {
 872         case RPM_REQ_NONE:
 873                 break;
 874         case RPM_REQ_IDLE:
 875                 rpm_idle(dev, RPM_NOWAIT);
 876                 break;
 877         case RPM_REQ_SUSPEND:
 878                 rpm_suspend(dev, RPM_NOWAIT);
 879                 break;
 880         case RPM_REQ_AUTOSUSPEND:
 881                 rpm_suspend(dev, RPM_NOWAIT | RPM_AUTO);
 882                 break;
 883         case RPM_REQ_RESUME:
 884                 rpm_resume(dev, RPM_NOWAIT);
 885                 break;
 886         }
 887
 888  out:
 889         spin_unlock_irq(&dev->power.lock);
 890 }
 891
 892 /**
 893  * pm_suspend_timer_fn - Timer function for pm_schedule_suspend().
 894  * @data: Device pointer passed by pm_schedule_suspend().
 895  *
 896  * Check if the time is right and queue a suspend request.
 897  */
 898 static void pm_suspend_timer_fn(struct timer_list *t)
 899 {
 900         struct device *dev = from_timer(dev, t, power.suspend_timer);
 901         unsigned long flags;
 902         unsigned long expires;
 903
 904         spin_lock_irqsave(&dev->power.lock, flags);
 905
 906         expires = dev->power.timer_expires;
 907         /* If 'expire' is after 'jiffies' we've been called too early. */
 908         if (expires > 0 && !time_after(expires, jiffies)) {
 909                 dev->power.timer_expires = 0;
 910                 rpm_suspend(dev, dev->power.timer_autosuspends ?
 911                     (RPM_ASYNC | RPM_AUTO) : RPM_ASYNC);
 912         }
 913
 914         spin_unlock_irqrestore(&dev->power.lock, flags);
 915 }
 916
 917 /**
 918  * pm_schedule_suspend - Set up a timer to submit a suspend request in future.
 919  * @dev: Device to suspend.
 920  * @delay: Time to wait before submitting a suspend request, in milliseconds.
 921  */
 922 int pm_schedule_suspend(struct device *dev, unsigned int delay)
 923 {
 924         unsigned long flags;
 925         int retval;
 926
 927         spin_lock_irqsave(&dev->power.lock, flags);
 928
 929         if (!delay) {
 930                 retval = rpm_suspend(dev, RPM_ASYNC);
 931                 goto out;
 932         }
 933
 934         retval = rpm_check_suspend_allowed(dev);
 935         if (retval)
 936                 goto out;
 937
 938         /* Other scheduled or pending requests need to be canceled. */
 939         pm_runtime_cancel_pending(dev);
 940
 941         dev->power.timer_expires = jiffies + msecs_to_jiffies(delay);
 942         dev->power.timer_expires += !dev->power.timer_expires;
 943         dev->power.timer_autosuspends = 0;
 944         mod_timer(&dev->power.suspend_timer, dev->power.timer_expires);
 945
 946  out:
 947         spin_unlock_irqrestore(&dev->power.lock, flags);
 948
 949         return retval;
 950 }
 951 EXPORT_SYMBOL_GPL(pm_schedule_suspend);
 952
 953 /**
 954  * __pm_runtime_idle - Entry point for runtime idle operations.
 955  * @dev: Device to send idle notification for.
 956  * @rpmflags: Flag bits.
 957  *
 958  * If the RPM_GET_PUT flag is set, decrement the device's usage count and
 959  * return immediately if it is larger than zero.  Then carry out an idle
 960  * notification, either synchronous or asynchronous.
 961  *
 962  * This routine may be called in atomic context if the RPM_ASYNC flag is set,
 963  * or if pm_runtime_irq_safe() has been called.
 964  */
 965 int __pm_runtime_idle(struct device *dev, int rpmflags)
 966 {
 967         unsigned long flags;
 968         int retval;
 969
 970         if (rpmflags & RPM_GET_PUT) {
 971                 if (!atomic_dec_and_test(&dev->power.usage_count))
 972                         return 0;
 973         }
 974
 975         might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);
 976
 977         spin_lock_irqsave(&dev->power.lock, flags);
 978         retval = rpm_idle(dev, rpmflags);
 979         spin_unlock_irqrestore(&dev->power.lock, flags);
 980
 981         return retval;
 982 }
 983 EXPORT_SYMBOL_GPL(__pm_runtime_idle);
 984
 985 /**
 986  * __pm_runtime_suspend - Entry point for runtime put/suspend operations.
 987  * @dev: Device to suspend.
 988  * @rpmflags: Flag bits.
 989  *
 990  * If the RPM_GET_PUT flag is set, decrement the device's usage count and
 991  * return immediately if it is larger than zero.  Then carry out a suspend,
 992  * either synchronous or asynchronous.
 993  *
 994  * This routine may be called in atomic context if the RPM_ASYNC flag is set,
 995  * or if pm_runtime_irq_safe() has been called.
 996  */
 997 int __pm_runtime_suspend(struct device *dev, int rpmflags)
 998 {
 999         unsigned long flags;
1000         int retval;
1001
1002         if (rpmflags & RPM_GET_PUT) {
1003                 if (!atomic_dec_and_test(&dev->power.usage_count))
1004                         return 0;
1005         }
1006
1007         might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);
1008
1009         spin_lock_irqsave(&dev->power.lock, flags);
1010         retval = rpm_suspend(dev, rpmflags);
1011         spin_unlock_irqrestore(&dev->power.lock, flags);
1012
1013         return retval;
1014 }
1015 EXPORT_SYMBOL_GPL(__pm_runtime_suspend);
1016
1017 /**
1018  * __pm_runtime_resume - Entry point for runtime resume operations.
1019  * @dev: Device to resume.
1020  * @rpmflags: Flag bits.
1021  *
1022  * If the RPM_GET_PUT flag is set, increment the device's usage count.  Then
1023  * carry out a resume, either synchronous or asynchronous.
1024  *
1025  * This routine may be called in atomic context if the RPM_ASYNC flag is set,
1026  * or if pm_runtime_irq_safe() has been called.
1027  */
1028 int __pm_runtime_resume(struct device *dev, int rpmflags)
1029 {
1030         unsigned long flags;
1031         int retval;
1032
1033         might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe &&
1034                         dev->power.runtime_status != RPM_ACTIVE);
1035
1036         if (rpmflags & RPM_GET_PUT)
1037                 atomic_inc(&dev->power.usage_count);
1038
1039         spin_lock_irqsave(&dev->power.lock, flags);
1040         retval = rpm_resume(dev, rpmflags);
1041         spin_unlock_irqrestore(&dev->power.lock, flags);
1042
1043         return retval;
1044 }
1045 EXPORT_SYMBOL_GPL(__pm_runtime_resume);
1046
1047 /**
1048  * pm_runtime_get_if_in_use - Conditionally bump up the device's usage counter.
1049  * @dev: Device to handle.
1050  *
1051  * Return -EINVAL if runtime PM is disabled for the device.
1052  *
1053  * If that's not the case and if the device's runtime PM status is RPM_ACTIVE
1054  * and the runtime PM usage counter is nonzero, increment the counter and
1055  * return 1.  Otherwise return 0 without changing the counter.
1056  */
1057 int pm_runtime_get_if_in_use(struct device *dev)
1058 {
1059         unsigned long flags;
1060         int retval;
1061
1062         spin_lock_irqsave(&dev->power.lock, flags);
1063         retval = dev->power.disable_depth > 0 ? -EINVAL :
1064                 dev->power.runtime_status == RPM_ACTIVE
1065                         && atomic_inc_not_zero(&dev->power.usage_count);
1066         spin_unlock_irqrestore(&dev->power.lock, flags);
1067         return retval;
1068 }
1069 EXPORT_SYMBOL_GPL(pm_runtime_get_if_in_use);
1070
1071 /**
1072  * __pm_runtime_set_status - Set runtime PM status of a device.
1073  * @dev: Device to handle.
1074  * @status: New runtime PM status of the device.
1075  *
1076  * If runtime PM of the device is disabled or its power.runtime_error field is
1077  * different from zero, the status may be changed either to RPM_ACTIVE, or to
1078  * RPM_SUSPENDED, as long as that reflects the actual state of the device.
1079  * However, if the device has a parent and the parent is not active, and the
1080  * parent's power.ignore_children flag is unset, the device's status cannot be
1081  * set to RPM_ACTIVE, so -EBUSY is returned in that case.
1082  *
1083  * If successful, __pm_runtime_set_status() clears the power.runtime_error field
1084  * and the device parent's counter of unsuspended children is modified to
1085  * reflect the new status.  If the new status is RPM_SUSPENDED, an idle
1086  * notification request for the parent is submitted.
1087  */
1088 int __pm_runtime_set_status(struct device *dev, unsigned int status)
1089 {
1090         struct device *parent = dev->parent;
1091         unsigned long flags;
1092         bool notify_parent = false;
1093         int error = 0;
1094
1095         if (status != RPM_ACTIVE && status != RPM_SUSPENDED)
1096                 return -EINVAL;
1097
1098         spin_lock_irqsave(&dev->power.lock, flags);
1099
1100         if (!dev->power.runtime_error && !dev->power.disable_depth) {
1101                 error = -EAGAIN;
1102                 goto out;
1103         }
1104
1105         if (dev->power.runtime_status == status || !parent)
1106                 goto out_set;
1107
1108         if (status == RPM_SUSPENDED) {
1109                 atomic_add_unless(&parent->power.child_count, -1, 0);
1110                 notify_parent = !parent->power.ignore_children;
1111         } else {
1112                 spin_lock_nested(&parent->power.lock, SINGLE_DEPTH_NESTING);
1113
1114                 /*
1115                  * It is invalid to put an active child under a parent that is
1116                  * not active, has runtime PM enabled and the
1117                  * 'power.ignore_children' flag unset.
1118                  */
1119                 if (!parent->power.disable_depth
1120                     && !parent->power.ignore_children
1121                     && parent->power.runtime_status != RPM_ACTIVE) {
1122                         dev_err(dev, "runtime PM trying to activate child device %s but parent (%s) is not active\n",
1123                                 dev_name(dev),
1124                                 dev_name(parent));
1125                         error = -EBUSY;
1126                 } else if (dev->power.runtime_status == RPM_SUSPENDED) {
1127                         atomic_inc(&parent->power.child_count);
1128                 }
1129
1130                 spin_unlock(&parent->power.lock);
1131
1132                 if (error)
1133                         goto out;
1134         }
1135
1136  out_set:
1137         __update_runtime_status(dev, status);
1138         dev->power.runtime_error = 0;
1139  out:
1140         spin_unlock_irqrestore(&dev->power.lock, flags);
1141
1142         if (notify_parent)
1143                 pm_request_idle(parent);
1144
1145         return error;
1146 }
1147 EXPORT_SYMBOL_GPL(__pm_runtime_set_status);
1148
1149 /**
1150  * __pm_runtime_barrier - Cancel pending requests and wait for completions.
1151  * @dev: Device to handle.
1152  *
1153  * Flush all pending requests for the device from pm_wq and wait for all
1154  * runtime PM operations involving the device in progress to complete.
1155  *
1156  * Should be called under dev->power.lock with interrupts disabled.
1157  */
1158 static void __pm_runtime_barrier(struct device *dev)
1159 {
1160         pm_runtime_deactivate_timer(dev);
1161
1162         if (dev->power.request_pending) {
1163                 dev->power.request = RPM_REQ_NONE;
1164                 spin_unlock_irq(&dev->power.lock);
1165
1166                 cancel_work_sync(&dev->power.work);
1167
1168                 spin_lock_irq(&dev->power.lock);
1169                 dev->power.request_pending = false;
1170         }
1171
1172         if (dev->power.runtime_status == RPM_SUSPENDING
1173             || dev->power.runtime_status == RPM_RESUMING
1174             || dev->power.idle_notification) {
1175                 DEFINE_WAIT(wait);
1176
1177                 /* Suspend, wake-up or idle notification in progress. */
1178                 for (;;) {
1179                         prepare_to_wait(&dev->power.wait_queue, &wait,
1180                                         TASK_UNINTERRUPTIBLE);
1181                         if (dev->power.runtime_status != RPM_SUSPENDING
1182                             && dev->power.runtime_status != RPM_RESUMING
1183                             && !dev->power.idle_notification)
1184                                 break;
1185                         spin_unlock_irq(&dev->power.lock);
1186
1187                         schedule();
1188
1189                         spin_lock_irq(&dev->power.lock);
1190                 }
1191                 finish_wait(&dev->power.wait_queue, &wait);
1192         }
1193 }
1194
1195 /**
1196  * pm_runtime_barrier - Flush pending requests and wait for completions.
1197  * @dev: Device to handle.
1198  *
1199  * Prevent the device from being suspended by incrementing its usage counter and
1200  * if there's a pending resume request for the device, wake the device up.
1201  * Next, make sure that all pending requests for the device have been flushed
1202  * from pm_wq and wait for all runtime PM operations involving the device in
1203  * progress to complete.
1204  *
1205  * Return value:
1206  * 1, if there was a resume request pending and the device had to be woken up,
1207  * 0, otherwise
1208  */
1209 int pm_runtime_barrier(struct device *dev)
1210 {
1211         int retval = 0;
1212
1213         pm_runtime_get_noresume(dev);
1214         spin_lock_irq(&dev->power.lock);
1215
1216         if (dev->power.request_pending
1217             && dev->power.request == RPM_REQ_RESUME) {
1218                 rpm_resume(dev, 0);
1219                 retval = 1;
1220         }
1221
1222         __pm_runtime_barrier(dev);
1223
1224         spin_unlock_irq(&dev->power.lock);
1225         pm_runtime_put_noidle(dev);
1226
1227         return retval;
1228 }
1229 EXPORT_SYMBOL_GPL(pm_runtime_barrier);
1230
1231 /**
1232  * __pm_runtime_disable - Disable runtime PM of a device.
1233  * @dev: Device to handle.
1234  * @check_resume: If set, check if there's a resume request for the device.
1235  *
1236  * Increment power.disable_depth for the device and if it was zero previously,
1237  * cancel all pending runtime PM requests for the device and wait for all
1238  * operations in progress to complete.  The device can be either active or
1239  * suspended after its runtime PM has been disabled.
1240  *
1241  * If @check_resume is set and there's a resume request pending when
1242  * __pm_runtime_disable() is called and power.disable_depth is zero, the
1243  * function will wake up the device before disabling its runtime PM.
1244  */
1245 void __pm_runtime_disable(struct device *dev, bool check_resume)
1246 {
1247         spin_lock_irq(&dev->power.lock);
1248
1249         if (dev->power.disable_depth > 0) {
1250                 dev->power.disable_depth++;
1251                 goto out;
1252         }
1253
1254         /*
1255          * Wake up the device if there's a resume request pending, because that
1256          * means there probably is some I/O to process and disabling runtime PM
1257          * shouldn't prevent the device from processing the I/O.
1258          */
1259         if (check_resume && dev->power.request_pending
1260             && dev->power.request == RPM_REQ_RESUME) {
1261                 /*
1262                  * Prevent suspends and idle notifications from being carried
1263                  * out after we have woken up the device.
1264                  */
1265                 pm_runtime_get_noresume(dev);
1266
1267                 rpm_resume(dev, 0);
1268
1269                 pm_runtime_put_noidle(dev);
1270         }
1271
1272         if (!dev->power.disable_depth++)
1273                 __pm_runtime_barrier(dev);
1274
1275  out:
1276         spin_unlock_irq(&dev->power.lock);
1277 }
1278 EXPORT_SYMBOL_GPL(__pm_runtime_disable);
1279
1280 /**
1281  * pm_runtime_enable - Enable runtime PM of a device.
1282  * @dev: Device to handle.
1283  */
1284 void pm_runtime_enable(struct device *dev)
1285 {
1286         unsigned long flags;
1287
1288         spin_lock_irqsave(&dev->power.lock, flags);
1289
1290         if (dev->power.disable_depth > 0)
1291                 dev->power.disable_depth--;
1292         else
1293                 dev_warn(dev, "Unbalanced %s!\n", __func__);
1294
1295         WARN(!dev->power.disable_depth &&
1296              dev->power.runtime_status == RPM_SUSPENDED &&
1297              !dev->power.ignore_children &&
1298              atomic_read(&dev->power.child_count) > 0,
1299              "Enabling runtime PM for inactive device (%s) with active children\n",
1300              dev_name(dev));
1301
1302         spin_unlock_irqrestore(&dev->power.lock, flags);
1303 }
1304 EXPORT_SYMBOL_GPL(pm_runtime_enable);
1305
1306 /**
1307  * pm_runtime_forbid - Block runtime PM of a device.
1308  * @dev: Device to handle.
1309  *
1310  * Increase the device's usage count and clear its power.runtime_auto flag,
1311  * so that it cannot be suspended at run time until pm_runtime_allow() is called
1312  * for it.
1313  */
1314 void pm_runtime_forbid(struct device *dev)
1315 {
1316         spin_lock_irq(&dev->power.lock);
1317         if (!dev->power.runtime_auto)
1318                 goto out;
1319
1320         dev->power.runtime_auto = false;
1321         atomic_inc(&dev->power.usage_count);
1322         rpm_resume(dev, 0);
1323
1324  out:
1325         spin_unlock_irq(&dev->power.lock);
1326 }
1327 EXPORT_SYMBOL_GPL(pm_runtime_forbid);
1328
1329 /**
1330  * pm_runtime_allow - Unblock runtime PM of a device.
1331  * @dev: Device to handle.
1332  *
1333  * Decrease the device's usage count and set its power.runtime_auto flag.
1334  */
1335 void pm_runtime_allow(struct device *dev)
1336 {
1337         spin_lock_irq(&dev->power.lock);
1338         if (dev->power.runtime_auto)
1339                 goto out;
1340
1341         dev->power.runtime_auto = true;
1342         if (atomic_dec_and_test(&dev->power.usage_count))
1343                 rpm_idle(dev, RPM_AUTO | RPM_ASYNC);
1344
1345  out:
1346         spin_unlock_irq(&dev->power.lock);
1347 }
1348 EXPORT_SYMBOL_GPL(pm_runtime_allow);
1349
1350 /**
1351  * pm_runtime_no_callbacks - Ignore runtime PM callbacks for a device.
1352  * @dev: Device to handle.
1353  *
1354  * Set the power.no_callbacks flag, which tells the PM core that this
1355  * device is power-managed through its parent and has no runtime PM
1356  * callbacks of its own.  The runtime sysfs attributes will be removed.
1357  */
1358 void pm_runtime_no_callbacks(struct device *dev)
1359 {
1360         spin_lock_irq(&dev->power.lock);
1361         dev->power.no_callbacks = 1;
1362         spin_unlock_irq(&dev->power.lock);
1363         if (device_is_registered(dev))
1364                 rpm_sysfs_remove(dev);
1365 }
1366 EXPORT_SYMBOL_GPL(pm_runtime_no_callbacks);
1367
1368 /**
1369  * pm_runtime_irq_safe - Leave interrupts disabled during callbacks.
1370  * @dev: Device to handle
1371  *
1372  * Set the power.irq_safe flag, which tells the PM core that the
1373  * ->runtime_suspend() and ->runtime_resume() callbacks for this device should
1374  * always be invoked with the spinlock held and interrupts disabled.  It also
1375  * causes the parent's usage counter to be permanently incremented, preventing
1376  * the parent from runtime suspending -- otherwise an irq-safe child might have
1377  * to wait for a non-irq-safe parent.
1378  */
1379 void pm_runtime_irq_safe(struct device *dev)
1380 {
1381         if (dev->parent)
1382                 pm_runtime_get_sync(dev->parent);
1383         spin_lock_irq(&dev->power.lock);
1384         dev->power.irq_safe = 1;
1385         spin_unlock_irq(&dev->power.lock);
1386 }
1387 EXPORT_SYMBOL_GPL(pm_runtime_irq_safe);
1388
1389 /**
1390  * update_autosuspend - Handle a change to a device's autosuspend settings.
1391  * @dev: Device to handle.
1392  * @old_delay: The former autosuspend_delay value.
1393  * @old_use: The former use_autosuspend value.
1394  *
1395  * Prevent runtime suspend if the new delay is negative and use_autosuspend is
1396  * set; otherwise allow it.  Send an idle notification if suspends are allowed.
1397  *
1398  * This function must be called under dev->power.lock with interrupts disabled.
1399  */
1400 static void update_autosuspend(struct device *dev, int old_delay, int old_use)
1401 {
1402         int delay = dev->power.autosuspend_delay;
1403
1404         /* Should runtime suspend be prevented now? */
1405         if (dev->power.use_autosuspend && delay < 0) {
1406
1407                 /* If it used to be allowed then prevent it. */
1408                 if (!old_use || old_delay >= 0) {
1409                         atomic_inc(&dev->power.usage_count);
1410                         rpm_resume(dev, 0);
1411                 }
1412         }
1413
1414         /* Runtime suspend should be allowed now. */
1415         else {
1416
1417                 /* If it used to be prevented then allow it. */
1418                 if (old_use && old_delay < 0)
1419                         atomic_dec(&dev->power.usage_count);
1420
1421                 /* Maybe we can autosuspend now. */
1422                 rpm_idle(dev, RPM_AUTO);
1423         }
1424 }
1425
1426 /**
1427  * pm_runtime_set_autosuspend_delay - Set a device's autosuspend_delay value.
1428  * @dev: Device to handle.
1429  * @delay: Value of the new delay in milliseconds.
1430  *
1431  * Set the device's power.autosuspend_delay value.  If it changes to negative
1432  * and the power.use_autosuspend flag is set, prevent runtime suspends.  If it
1433  * changes the other way, allow runtime suspends.
1434  */
1435 void pm_runtime_set_autosuspend_delay(struct device *dev, int delay)
1436 {
1437         int old_delay, old_use;
1438
1439         spin_lock_irq(&dev->power.lock);
1440         old_delay = dev->power.autosuspend_delay;
1441         old_use = dev->power.use_autosuspend;
1442         dev->power.autosuspend_delay = delay;
1443         update_autosuspend(dev, old_delay, old_use);
1444         spin_unlock_irq(&dev->power.lock);
1445 }
1446 EXPORT_SYMBOL_GPL(pm_runtime_set_autosuspend_delay);
1447
1448 /**
1449  * __pm_runtime_use_autosuspend - Set a device's use_autosuspend flag.
1450  * @dev: Device to handle.
1451  * @use: New value for use_autosuspend.
1452  *
1453  * Set the device's power.use_autosuspend flag, and allow or prevent runtime
1454  * suspends as needed.
1455  */
1456 void __pm_runtime_use_autosuspend(struct device *dev, bool use)
1457 {
1458         int old_delay, old_use;
1459
1460         spin_lock_irq(&dev->power.lock);
1461         old_delay = dev->power.autosuspend_delay;
1462         old_use = dev->power.use_autosuspend;
1463         dev->power.use_autosuspend = use;
1464         update_autosuspend(dev, old_delay, old_use);
1465         spin_unlock_irq(&dev->power.lock);
1466 }
1467 EXPORT_SYMBOL_GPL(__pm_runtime_use_autosuspend);
1468
1469 /**
1470  * pm_runtime_init - Initialize runtime PM fields in given device object.
1471  * @dev: Device object to initialize.
1472  */
1473 void pm_runtime_init(struct device *dev)
1474 {
1475         dev->power.runtime_status = RPM_SUSPENDED;
1476         dev->power.idle_notification = false;
1477
1478         dev->power.disable_depth = 1;
1479         atomic_set(&dev->power.usage_count, 0);
1480
1481         dev->power.runtime_error = 0;
1482
1483         atomic_set(&dev->power.child_count, 0);
1484         pm_suspend_ignore_children(dev, false);
1485         dev->power.runtime_auto = true;
1486
1487         dev->power.request_pending = false;
1488         dev->power.request = RPM_REQ_NONE;
1489         dev->power.deferred_resume = false;
1490         dev->power.accounting_timestamp = jiffies;
1491         INIT_WORK(&dev->power.work, pm_runtime_work);
1492
1493         dev->power.timer_expires = 0;
1494         timer_setup(&dev->power.suspend_timer, pm_suspend_timer_fn, 0);
1495
1496         init_waitqueue_head(&dev->power.wait_queue);
1497 }
1498
1499 /**
1500  * pm_runtime_reinit - Re-initialize runtime PM fields in given device object.
1501  * @dev: Device object to re-initialize.
1502  */
1503 void pm_runtime_reinit(struct device *dev)
1504 {
1505         if (!pm_runtime_enabled(dev)) {
1506                 if (dev->power.runtime_status == RPM_ACTIVE)
1507                         pm_runtime_set_suspended(dev);
1508                 if (dev->power.irq_safe) {
1509                         spin_lock_irq(&dev->power.lock);
1510                         dev->power.irq_safe = 0;
1511                         spin_unlock_irq(&dev->power.lock);
1512                         if (dev->parent)
1513                                 pm_runtime_put(dev->parent);
1514                 }
1515         }
1516 }
1517
1518 /**
1519  * pm_runtime_remove - Prepare for removing a device from device hierarchy.
1520  * @dev: Device object being removed from device hierarchy.
1521  */
1522 void pm_runtime_remove(struct device *dev)
1523 {
1524         __pm_runtime_disable(dev, false);
1525         pm_runtime_reinit(dev);
1526 }
1527
1528 /**
1529  * pm_runtime_clean_up_links - Prepare links to consumers for driver removal.
1530  * @dev: Device whose driver is going to be removed.
1531  *
1532  * Check links from this device to any consumers and if any of them have active
1533  * runtime PM references to the device, drop the usage counter of the device
1534  * (once per link).
1535  *
1536  * Links with the DL_FLAG_STATELESS flag set are ignored.
1537  *
1538  * Since the device is guaranteed to be runtime-active at the point this is
1539  * called, nothing else needs to be done here.
1540  *
1541  * Moreover, this is called after device_links_busy() has returned 'false', so
1542  * the status of each link is guaranteed to be DL_STATE_SUPPLIER_UNBIND and
1543  * therefore rpm_active can't be manipulated concurrently.
1544  */
1545 void pm_runtime_clean_up_links(struct device *dev)
1546 {
1547         struct device_link *link;
1548         int idx;
1549
1550         idx = device_links_read_lock();
1551
1552         list_for_each_entry_rcu(link, &dev->links.consumers, s_node) {
1553                 if (link->flags & DL_FLAG_STATELESS)
1554                         continue;
1555
1556                 if (link->rpm_active) {
1557                         pm_runtime_put_noidle(dev);
1558                         link->rpm_active = false;
1559                 }
1560         }
1561
1562         device_links_read_unlock(idx);
1563 }
1564
1565 /**
1566  * pm_runtime_get_suppliers - Resume and reference-count supplier devices.
1567  * @dev: Consumer device.
1568  */
1569 void pm_runtime_get_suppliers(struct device *dev)
1570 {
1571         struct device_link *link;
1572         int idx;
1573
1574         idx = device_links_read_lock();
1575
1576         list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
1577                 if (link->flags & DL_FLAG_PM_RUNTIME)
1578                         pm_runtime_get_sync(link->supplier);
1579
1580         device_links_read_unlock(idx);
1581 }
1582
1583 /**
1584  * pm_runtime_put_suppliers - Drop references to supplier devices.
1585  * @dev: Consumer device.
1586  */
1587 void pm_runtime_put_suppliers(struct device *dev)
1588 {
1589         struct device_link *link;
1590         int idx;
1591
1592         idx = device_links_read_lock();
1593
1594         list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
1595                 if (link->flags & DL_FLAG_PM_RUNTIME)
1596                         pm_runtime_put(link->supplier);
1597
1598         device_links_read_unlock(idx);
1599 }
1600
1601 void pm_runtime_new_link(struct device *dev)
1602 {
1603         spin_lock_irq(&dev->power.lock);
1604         dev->power.links_count++;
1605         spin_unlock_irq(&dev->power.lock);
1606 }
1607
1608 void pm_runtime_drop_link(struct device *dev)
1609 {
1610         spin_lock_irq(&dev->power.lock);
1611         WARN_ON(dev->power.links_count == 0);
1612         dev->power.links_count--;
1613         spin_unlock_irq(&dev->power.lock);
1614 }
1615
1616 static bool pm_runtime_need_not_resume(struct device *dev)
1617 {
1618         return atomic_read(&dev->power.usage_count) <= 1 &&
1619                 (atomic_read(&dev->power.child_count) == 0 ||
1620                  dev->power.ignore_children);
1621 }
1622
1623 /**
1624  * pm_runtime_force_suspend - Force a device into suspend state if needed.
1625  * @dev: Device to suspend.
1626  *
1627  * Disable runtime PM so we safely can check the device's runtime PM status and
1628  * if it is active, invoke its ->runtime_suspend callback to suspend it and
1629  * change its runtime PM status field to RPM_SUSPENDED.  Also, if the device's
1630  * usage and children counters don't indicate that the device was in use before
1631  * the system-wide transition under way, decrement its parent's children counter
1632  * (if there is a parent).  Keep runtime PM disabled to preserve the state
1633  * unless we encounter errors.
1634  *
1635  * Typically this function may be invoked from a system suspend callback to make
1636  * sure the device is put into low power state and it should only be used during
1637  * system-wide PM transitions to sleep states.  It assumes that the analogous
1638  * pm_runtime_force_resume() will be used to resume the device.
1639  */
1640 int pm_runtime_force_suspend(struct device *dev)
1641 {
1642         int (*callback)(struct device *);
1643         int ret;
1644
1645         pm_runtime_disable(dev);
1646         if (pm_runtime_status_suspended(dev))
1647                 return 0;
1648
1649         callback = RPM_GET_CALLBACK(dev, runtime_suspend);
1650
1651         ret = callback ? callback(dev) : 0;
1652         if (ret)
1653                 goto err;
1654
1655         /*
1656          * If the device can stay in suspend after the system-wide transition
1657          * to the working state that will follow, drop the children counter of
1658          * its parent, but set its status to RPM_SUSPENDED anyway in case this
1659          * function will be called again for it in the meantime.
1660          */
1661         if (pm_runtime_need_not_resume(dev))
1662                 pm_runtime_set_suspended(dev);
1663         else
1664                 __update_runtime_status(dev, RPM_SUSPENDED);
1665
1666         return 0;
1667
1668 err:
1669         pm_runtime_enable(dev);
1670         return ret;
1671 }
1672 EXPORT_SYMBOL_GPL(pm_runtime_force_suspend);
1673
1674 /**
1675  * pm_runtime_force_resume - Force a device into resume state if needed.
1676  * @dev: Device to resume.
1677  *
1678  * Prior invoking this function we expect the user to have brought the device
1679  * into low power state by a call to pm_runtime_force_suspend(). Here we reverse
1680  * those actions and bring the device into full power, if it is expected to be
1681  * used on system resume.  In the other case, we defer the resume to be managed
1682  * via runtime PM.
1683  *
1684  * Typically this function may be invoked from a system resume callback.
1685  */
1686 int pm_runtime_force_resume(struct device *dev)
1687 {
1688         int (*callback)(struct device *);
1689         int ret = 0;
1690
1691         if (!pm_runtime_status_suspended(dev) || pm_runtime_need_not_resume(dev))
1692                 goto out;
1693
1694         /*
1695          * The value of the parent's children counter is correct already, so
1696          * just update the status of the device.
1697          */
1698         __update_runtime_status(dev, RPM_ACTIVE);
1699
1700         callback = RPM_GET_CALLBACK(dev, runtime_resume);
1701
1702         ret = callback ? callback(dev) : 0;
1703         if (ret) {
1704                 pm_runtime_set_suspended(dev);
1705                 goto out;
1706         }
1707
1708         pm_runtime_mark_last_busy(dev);
1709 out:
1710         pm_runtime_enable(dev);
1711         return ret;
1712 }
1713 EXPORT_SYMBOL_GPL(pm_runtime_force_resume);