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/ktime.h>
  12 #include <linux/hrtimer.h>
  13 #include <linux/export.h>
  14 #include <linux/pm_runtime.h>
  15 #include <linux/pm_wakeirq.h>
  16 #include <trace/events/rpm.h>
  17
  18 #include "../base.h"
  19 #include "power.h"
  20
  21 typedef int (*pm_callback_t)(struct device *);
  22
  23 static pm_callback_t __rpm_get_callback(struct device *dev, size_t cb_offset)
  24 {
  25         pm_callback_t cb;
  26         const struct dev_pm_ops *ops;
  27
  28         if (dev->pm_domain)
  29                 ops = &dev->pm_domain->ops;
  30         else if (dev->type && dev->type->pm)
  31                 ops = dev->type->pm;
  32         else if (dev->class && dev->class->pm)
  33                 ops = dev->class->pm;
  34         else if (dev->bus && dev->bus->pm)
  35                 ops = dev->bus->pm;
  36         else
  37                 ops = NULL;
  38
  39         if (ops)
  40                 cb = *(pm_callback_t *)((void *)ops + cb_offset);
  41         else
  42                 cb = NULL;
  43
  44         if (!cb && dev->driver && dev->driver->pm)
  45                 cb = *(pm_callback_t *)((void *)dev->driver->pm + cb_offset);
  46
  47         return cb;
  48 }
  49
  50 #define RPM_GET_CALLBACK(dev, callback) \
  51                 __rpm_get_callback(dev, offsetof(struct dev_pm_ops, callback))
  52
  53 static int rpm_resume(struct device *dev, int rpmflags);
  54 static int rpm_suspend(struct device *dev, int rpmflags);
  55
  56 /**
  57  * update_pm_runtime_accounting - Update the time accounting of power states
  58  * @dev: Device to update the accounting for
  59  *
  60  * In order to be able to have time accounting of the various power states
  61  * (as used by programs such as PowerTOP to show the effectiveness of runtime
  62  * PM), we need to track the time spent in each state.
  63  * update_pm_runtime_accounting must be called each time before the
  64  * runtime_status field is updated, to account the time in the old state
  65  * correctly.
  66  */
  67 void update_pm_runtime_accounting(struct device *dev)
  68 {
  69         unsigned long now = jiffies;
  70         unsigned long delta;
  71
  72         delta = now - dev->power.accounting_timestamp;
  73
  74         dev->power.accounting_timestamp = now;
  75
  76         if (dev->power.disable_depth > 0)
  77                 return;
  78
  79         if (dev->power.runtime_status == RPM_SUSPENDED)
  80                 dev->power.suspended_jiffies += delta;
  81         else
  82                 dev->power.active_jiffies += delta;
  83 }
  84
  85 static void __update_runtime_status(struct device *dev, enum rpm_status status)
  86 {
  87         update_pm_runtime_accounting(dev);
  88         dev->power.runtime_status = status;
  89 }
  90
  91 /**
  92  * pm_runtime_deactivate_timer - Deactivate given device's suspend timer.
  93  * @dev: Device to handle.
  94  */
  95 static void pm_runtime_deactivate_timer(struct device *dev)
  96 {
  97         if (dev->power.timer_expires > 0) {
  98                 hrtimer_cancel(&dev->power.suspend_timer);
  99                 dev->power.timer_expires = 0;
 100         }
 101 }
 102
 103 /**
 104  * pm_runtime_cancel_pending - Deactivate suspend timer and cancel requests.
 105  * @dev: Device to handle.
 106  */
 107 static void pm_runtime_cancel_pending(struct device *dev)
 108 {
 109         pm_runtime_deactivate_timer(dev);
 110         /*
 111          * In case there's a request pending, make sure its work function will
 112          * return without doing anything.
 113          */
 114         dev->power.request = RPM_REQ_NONE;
 115 }
 116
 117 /*
 118  * pm_runtime_autosuspend_expiration - Get a device's autosuspend-delay expiration time.
 119  * @dev: Device to handle.
 120  *
 121  * Compute the autosuspend-delay expiration time based on the device's
 122  * power.last_busy time.  If the delay has already expired or is disabled
 123  * (negative) or the power.use_autosuspend flag isn't set, return 0.
 124  * Otherwise return the expiration time in jiffies (adjusted to be nonzero).
 125  *
 126  * This function may be called either with or without dev->power.lock held.
 127  * Either way it can be racy, since power.last_busy may be updated at any time.
 128  */
 129 u64 pm_runtime_autosuspend_expiration(struct device *dev)
 130 {
 131         int autosuspend_delay;
 132         u64 last_busy, expires = 0;
 133         u64 now = ktime_to_ns(ktime_get());
 134
 135         if (!dev->power.use_autosuspend)
 136                 goto out;
 137
 138         autosuspend_delay = READ_ONCE(dev->power.autosuspend_delay);
 139         if (autosuspend_delay < 0)
 140                 goto out;
 141
 142         last_busy = READ_ONCE(dev->power.last_busy);
 143
 144         expires = last_busy + autosuspend_delay * NSEC_PER_MSEC;
 145         if (expires <= now)
 146                 expires = 0;    /* Already expired. */
 147
 148  out:
 149         return expires;
 150 }
 151 EXPORT_SYMBOL_GPL(pm_runtime_autosuspend_expiration);
 152
 153 static int dev_memalloc_noio(struct device *dev, void *data)
 154 {
 155         return dev->power.memalloc_noio;
 156 }
 157
 158 /*
 159  * pm_runtime_set_memalloc_noio - Set a device's memalloc_noio flag.
 160  * @dev: Device to handle.
 161  * @enable: True for setting the flag and False for clearing the flag.
 162  *
 163  * Set the flag for all devices in the path from the device to the
 164  * root device in the device tree if @enable is true, otherwise clear
 165  * the flag for devices in the path whose siblings don't set the flag.
 166  *
 167  * The function should only be called by block device, or network
 168  * device driver for solving the deadlock problem during runtime
 169  * resume/suspend:
 170  *
 171  *     If memory allocation with GFP_KERNEL is called inside runtime
 172  *     resume/suspend callback of any one of its ancestors(or the
 173  *     block device itself), the deadlock may be triggered inside the
 174  *     memory allocation since it might not complete until the block
 175  *     device becomes active and the involed page I/O finishes. The
 176  *     situation is pointed out first by Alan Stern. Network device
 177  *     are involved in iSCSI kind of situation.
 178  *
 179  * The lock of dev_hotplug_mutex is held in the function for handling
 180  * hotplug race because pm_runtime_set_memalloc_noio() may be called
 181  * in async probe().
 182  *
 183  * The function should be called between device_add() and device_del()
 184  * on the affected device(block/network device).
 185  */
 186 void pm_runtime_set_memalloc_noio(struct device *dev, bool enable)
 187 {
 188         static DEFINE_MUTEX(dev_hotplug_mutex);
 189
 190         mutex_lock(&dev_hotplug_mutex);
 191         for (;;) {
 192                 bool enabled;
 193
 194                 /* hold power lock since bitfield is not SMP-safe. */
 195                 spin_lock_irq(&dev->power.lock);
 196                 enabled = dev->power.memalloc_noio;
 197                 dev->power.memalloc_noio = enable;
 198                 spin_unlock_irq(&dev->power.lock);
 199
 200                 /*
 201                  * not need to enable ancestors any more if the device
 202                  * has been enabled.
 203                  */
 204                 if (enabled && enable)
 205                         break;
 206
 207                 dev = dev->parent;
 208
 209                 /*
 210                  * clear flag of the parent device only if all the
 211                  * children don't set the flag because ancestor's
 212                  * flag was set by any one of the descendants.
 213                  */
 214                 if (!dev || (!enable &&
 215                              device_for_each_child(dev, NULL,
 216                                                    dev_memalloc_noio)))
 217                         break;
 218         }
 219         mutex_unlock(&dev_hotplug_mutex);
 220 }
 221 EXPORT_SYMBOL_GPL(pm_runtime_set_memalloc_noio);
 222
 223 /**
 224  * rpm_check_suspend_allowed - Test whether a device may be suspended.
 225  * @dev: Device to test.
 226  */
 227 static int rpm_check_suspend_allowed(struct device *dev)
 228 {
 229         int retval = 0;
 230
 231         if (dev->power.runtime_error)
 232                 retval = -EINVAL;
 233         else if (dev->power.disable_depth > 0)
 234                 retval = -EACCES;
 235         else if (atomic_read(&dev->power.usage_count) > 0)
 236                 retval = -EAGAIN;
 237         else if (!dev->power.ignore_children &&
 238                         atomic_read(&dev->power.child_count))
 239                 retval = -EBUSY;
 240
 241         /* Pending resume requests take precedence over suspends. */
 242         else if ((dev->power.deferred_resume
 243                         && dev->power.runtime_status == RPM_SUSPENDING)
 244             || (dev->power.request_pending
 245                         && dev->power.request == RPM_REQ_RESUME))
 246                 retval = -EAGAIN;
 247         else if (__dev_pm_qos_read_value(dev) == 0)
 248                 retval = -EPERM;
 249         else if (dev->power.runtime_status == RPM_SUSPENDED)
 250                 retval = 1;
 251
 252         return retval;
 253 }
 254
 255 static int rpm_get_suppliers(struct device *dev)
 256 {
 257         struct device_link *link;
 258
 259         list_for_each_entry_rcu(link, &dev->links.suppliers, c_node) {
 260                 int retval;
 261
 262                 if (!(link->flags & DL_FLAG_PM_RUNTIME))
 263                         continue;
 264
 265                 if (READ_ONCE(link->status) == DL_STATE_SUPPLIER_UNBIND ||
 266                     link->rpm_active)
 267                         continue;
 268
 269                 retval = pm_runtime_get_sync(link->supplier);
 270                 /* Ignore suppliers with disabled runtime PM. */
 271                 if (retval < 0 && retval != -EACCES) {
 272                         pm_runtime_put_noidle(link->supplier);
 273                         return retval;
 274                 }
 275                 link->rpm_active = true;
 276         }
 277         return 0;
 278 }
 279
 280 static void rpm_put_suppliers(struct device *dev)
 281 {
 282         struct device_link *link;
 283
 284         list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
 285                 if (link->rpm_active &&
 286                     READ_ONCE(link->status) != DL_STATE_SUPPLIER_UNBIND) {
 287                         pm_runtime_put(link->supplier);
 288                         link->rpm_active = false;
 289                 }
 290 }
 291
 292 /**
 293  * __rpm_callback - Run a given runtime PM callback for a given device.
 294  * @cb: Runtime PM callback to run.
 295  * @dev: Device to run the callback for.
 296  */
 297 static int __rpm_callback(int (*cb)(struct device *), struct device *dev)
 298         __releases(&dev->power.lock) __acquires(&dev->power.lock)
 299 {
 300         int retval, idx;
 301         bool use_links = dev->power.links_count > 0;
 302
 303         if (dev->power.irq_safe) {
 304                 spin_unlock(&dev->power.lock);
 305         } else {
 306                 spin_unlock_irq(&dev->power.lock);
 307
 308                 /*
 309                  * Resume suppliers if necessary.
 310                  *
 311                  * The device's runtime PM status cannot change until this
 312                  * routine returns, so it is safe to read the status outside of
 313                  * the lock.
 314                  */
 315                 if (use_links && dev->power.runtime_status == RPM_RESUMING) {
 316                         idx = device_links_read_lock();
 317
 318                         retval = rpm_get_suppliers(dev);
 319                         if (retval)
 320                                 goto fail;
 321
 322                         device_links_read_unlock(idx);
 323                 }
 324         }
 325
 326         retval = cb(dev);
 327
 328         if (dev->power.irq_safe) {
 329                 spin_lock(&dev->power.lock);
 330         } else {
 331                 /*
 332                  * If the device is suspending and the callback has returned
 333                  * success, drop the usage counters of the suppliers that have
 334                  * been reference counted on its resume.
 335                  *
 336                  * Do that if resume fails too.
 337                  */
 338                 if (use_links
 339                     && ((dev->power.runtime_status == RPM_SUSPENDING && !retval)
 340                     || (dev->power.runtime_status == RPM_RESUMING && retval))) {
 341                         idx = device_links_read_lock();
 342
 343  fail:
 344                         rpm_put_suppliers(dev);
 345
 346                         device_links_read_unlock(idx);
 347                 }
 348
 349                 spin_lock_irq(&dev->power.lock);
 350         }
 351
 352         return retval;
 353 }
 354
 355 /**
 356  * rpm_idle - Notify device bus type if the device can be suspended.
 357  * @dev: Device to notify the bus type about.
 358  * @rpmflags: Flag bits.
 359  *
 360  * Check if the device's runtime PM status allows it to be suspended.  If
 361  * another idle notification has been started earlier, return immediately.  If
 362  * the RPM_ASYNC flag is set then queue an idle-notification request; otherwise
 363  * run the ->runtime_idle() callback directly. If the ->runtime_idle callback
 364  * doesn't exist or if it returns 0, call rpm_suspend with the RPM_AUTO flag.
 365  *
 366  * This function must be called under dev->power.lock with interrupts disabled.
 367  */
 368 static int rpm_idle(struct device *dev, int rpmflags)
 369 {
 370         int (*callback)(struct device *);
 371         int retval;
 372
 373         trace_rpm_idle_rcuidle(dev, rpmflags);
 374         retval = rpm_check_suspend_allowed(dev);
 375         if (retval < 0)
 376                 ;       /* Conditions are wrong. */
 377
 378         /* Idle notifications are allowed only in the RPM_ACTIVE state. */
 379         else if (dev->power.runtime_status != RPM_ACTIVE)
 380                 retval = -EAGAIN;
 381
 382         /*
 383          * Any pending request other than an idle notification takes
 384          * precedence over us, except that the timer may be running.
 385          */
 386         else if (dev->power.request_pending &&
 387             dev->power.request > RPM_REQ_IDLE)
 388                 retval = -EAGAIN;
 389
 390         /* Act as though RPM_NOWAIT is always set. */
 391         else if (dev->power.idle_notification)
 392                 retval = -EINPROGRESS;
 393         if (retval)
 394                 goto out;
 395
 396         /* Pending requests need to be canceled. */
 397         dev->power.request = RPM_REQ_NONE;
 398
 399         if (dev->power.no_callbacks)
 400                 goto out;
 401
 402         /* Carry out an asynchronous or a synchronous idle notification. */
 403         if (rpmflags & RPM_ASYNC) {
 404                 dev->power.request = RPM_REQ_IDLE;
 405                 if (!dev->power.request_pending) {
 406                         dev->power.request_pending = true;
 407                         queue_work(pm_wq, &dev->power.work);
 408                 }
 409                 trace_rpm_return_int_rcuidle(dev, _THIS_IP_, 0);
 410                 return 0;
 411         }
 412
 413         dev->power.idle_notification = true;
 414
 415         callback = RPM_GET_CALLBACK(dev, runtime_idle);
 416
 417         if (callback)
 418                 retval = __rpm_callback(callback, dev);
 419
 420         dev->power.idle_notification = false;
 421         wake_up_all(&dev->power.wait_queue);
 422
 423  out:
 424         trace_rpm_return_int_rcuidle(dev, _THIS_IP_, retval);
 425         return retval ? retval : rpm_suspend(dev, rpmflags | RPM_AUTO);
 426 }
 427
 428 /**
 429  * rpm_callback - Run a given runtime PM callback for a given device.
 430  * @cb: Runtime PM callback to run.
 431  * @dev: Device to run the callback for.
 432  */
 433 static int rpm_callback(int (*cb)(struct device *), struct device *dev)
 434 {
 435         int retval;
 436
 437         if (!cb)
 438                 return -ENOSYS;
 439
 440         if (dev->power.memalloc_noio) {
 441                 unsigned int noio_flag;
 442
 443                 /*
 444                  * Deadlock might be caused if memory allocation with
 445                  * GFP_KERNEL happens inside runtime_suspend and
 446                  * runtime_resume callbacks of one block device's
 447                  * ancestor or the block device itself. Network
 448                  * device might be thought as part of iSCSI block
 449                  * device, so network device and its ancestor should
 450                  * be marked as memalloc_noio too.
 451                  */
 452                 noio_flag = memalloc_noio_save();
 453                 retval = __rpm_callback(cb, dev);
 454                 memalloc_noio_restore(noio_flag);
 455         } else {
 456                 retval = __rpm_callback(cb, dev);
 457         }
 458
 459         dev->power.runtime_error = retval;
 460         return retval != -EACCES ? retval : -EIO;
 461 }
 462
 463 /**
 464  * rpm_suspend - Carry out runtime suspend of given device.
 465  * @dev: Device to suspend.
 466  * @rpmflags: Flag bits.
 467  *
 468  * Check if the device's runtime PM status allows it to be suspended.
 469  * Cancel a pending idle notification, autosuspend or suspend. If
 470  * another suspend has been started earlier, either return immediately
 471  * or wait for it to finish, depending on the RPM_NOWAIT and RPM_ASYNC
 472  * flags. If the RPM_ASYNC flag is set then queue a suspend request;
 473  * otherwise run the ->runtime_suspend() callback directly. When
 474  * ->runtime_suspend succeeded, if a deferred resume was requested while
 475  * the callback was running then carry it out, otherwise send an idle
 476  * notification for its parent (if the suspend succeeded and both
 477  * ignore_children of parent->power and irq_safe of dev->power are not set).
 478  * If ->runtime_suspend failed with -EAGAIN or -EBUSY, and if the RPM_AUTO
 479  * flag is set and the next autosuspend-delay expiration time is in the
 480  * future, schedule another autosuspend attempt.
 481  *
 482  * This function must be called under dev->power.lock with interrupts disabled.
 483  */
 484 static int rpm_suspend(struct device *dev, int rpmflags)
 485         __releases(&dev->power.lock) __acquires(&dev->power.lock)
 486 {
 487         int (*callback)(struct device *);
 488         struct device *parent = NULL;
 489         int retval;
 490
 491         trace_rpm_suspend_rcuidle(dev, rpmflags);
 492
 493  repeat:
 494         retval = rpm_check_suspend_allowed(dev);
 495
 496         if (retval < 0)
 497                 ;       /* Conditions are wrong. */
 498
 499         /* Synchronous suspends are not allowed in the RPM_RESUMING state. */
 500         else if (dev->power.runtime_status == RPM_RESUMING &&
 501             !(rpmflags & RPM_ASYNC))
 502                 retval = -EAGAIN;
 503         if (retval)
 504                 goto out;
 505
 506         /* If the autosuspend_delay time hasn't expired yet, reschedule. */
 507         if ((rpmflags & RPM_AUTO)
 508             && dev->power.runtime_status != RPM_SUSPENDING) {
 509                 u64 expires = pm_runtime_autosuspend_expiration(dev);
 510
 511                 if (expires != 0) {
 512                         /* Pending requests need to be canceled. */
 513                         dev->power.request = RPM_REQ_NONE;
 514
 515                         /*
 516                          * Optimization: If the timer is already running and is
 517                          * set to expire at or before the autosuspend delay,
 518                          * avoid the overhead of resetting it.  Just let it
 519                          * expire; pm_suspend_timer_fn() will take care of the
 520                          * rest.
 521                          */
 522                         if (!(dev->power.timer_expires &&
 523                                         dev->power.timer_expires <= expires)) {
 524                                 /*
 525                                  * We add a slack of 25% to gather wakeups
 526                                  * without sacrificing the granularity.
 527                                  */
 528                                 u64 slack = READ_ONCE(dev->power.autosuspend_delay) *
 529                                                     (NSEC_PER_MSEC >> 2);
 530
 531                                 dev->power.timer_expires = expires;
 532                                 hrtimer_start_range_ns(&dev->power.suspend_timer,
 533                                                 ns_to_ktime(expires),
 534                                                 slack,
 535                                                 HRTIMER_MODE_ABS);
 536                         }
 537                         dev->power.timer_autosuspends = 1;
 538                         goto out;
 539                 }
 540         }
 541
 542         /* Other scheduled or pending requests need to be canceled. */
 543         pm_runtime_cancel_pending(dev);
 544
 545         if (dev->power.runtime_status == RPM_SUSPENDING) {
 546                 DEFINE_WAIT(wait);
 547
 548                 if (rpmflags & (RPM_ASYNC | RPM_NOWAIT)) {
 549                         retval = -EINPROGRESS;
 550                         goto out;
 551                 }
 552
 553                 if (dev->power.irq_safe) {
 554                         spin_unlock(&dev->power.lock);
 555
 556                         cpu_relax();
 557
 558                         spin_lock(&dev->power.lock);
 559                         goto repeat;
 560                 }
 561
 562                 /* Wait for the other suspend running in parallel with us. */
 563                 for (;;) {
 564                         prepare_to_wait(&dev->power.wait_queue, &wait,
 565                                         TASK_UNINTERRUPTIBLE);
 566                         if (dev->power.runtime_status != RPM_SUSPENDING)
 567                                 break;
 568
 569                         spin_unlock_irq(&dev->power.lock);
 570
 571                         schedule();
 572
 573                         spin_lock_irq(&dev->power.lock);
 574                 }
 575                 finish_wait(&dev->power.wait_queue, &wait);
 576                 goto repeat;
 577         }
 578
 579         if (dev->power.no_callbacks)
 580                 goto no_callback;       /* Assume success. */
 581
 582         /* Carry out an asynchronous or a synchronous suspend. */
 583         if (rpmflags & RPM_ASYNC) {
 584                 dev->power.request = (rpmflags & RPM_AUTO) ?
 585                     RPM_REQ_AUTOSUSPEND : RPM_REQ_SUSPEND;
 586                 if (!dev->power.request_pending) {
 587                         dev->power.request_pending = true;
 588                         queue_work(pm_wq, &dev->power.work);
 589                 }
 590                 goto out;
 591         }
 592
 593         __update_runtime_status(dev, RPM_SUSPENDING);
 594
 595         callback = RPM_GET_CALLBACK(dev, runtime_suspend);
 596
 597         dev_pm_enable_wake_irq_check(dev, true);
 598         retval = rpm_callback(callback, dev);
 599         if (retval)
 600                 goto fail;
 601
 602  no_callback:
 603         __update_runtime_status(dev, RPM_SUSPENDED);
 604         pm_runtime_deactivate_timer(dev);
 605
 606         if (dev->parent) {
 607                 parent = dev->parent;
 608                 atomic_add_unless(&parent->power.child_count, -1, 0);
 609         }
 610         wake_up_all(&dev->power.wait_queue);
 611
 612         if (dev->power.deferred_resume) {
 613                 dev->power.deferred_resume = false;
 614                 rpm_resume(dev, 0);
 615                 retval = -EAGAIN;
 616                 goto out;
 617         }
 618
 619         /* Maybe the parent is now able to suspend. */
 620         if (parent && !parent->power.ignore_children && !dev->power.irq_safe) {
 621                 spin_unlock(&dev->power.lock);
 622
 623                 spin_lock(&parent->power.lock);
 624                 rpm_idle(parent, RPM_ASYNC);
 625                 spin_unlock(&parent->power.lock);
 626
 627                 spin_lock(&dev->power.lock);
 628         }
 629
 630  out:
 631         trace_rpm_return_int_rcuidle(dev, _THIS_IP_, retval);
 632
 633         return retval;
 634
 635  fail:
 636         dev_pm_disable_wake_irq_check(dev);
 637         __update_runtime_status(dev, RPM_ACTIVE);
 638         dev->power.deferred_resume = false;
 639         wake_up_all(&dev->power.wait_queue);
 640
 641         if (retval == -EAGAIN || retval == -EBUSY) {
 642                 dev->power.runtime_error = 0;
 643
 644                 /*
 645                  * If the callback routine failed an autosuspend, and
 646                  * if the last_busy time has been updated so that there
 647                  * is a new autosuspend expiration time, automatically
 648                  * reschedule another autosuspend.
 649                  */
 650                 if ((rpmflags & RPM_AUTO) &&
 651                     pm_runtime_autosuspend_expiration(dev) != 0)
 652                         goto repeat;
 653         } else {
 654                 pm_runtime_cancel_pending(dev);
 655         }
 656         goto out;
 657 }
 658
 659 /**
 660  * rpm_resume - Carry out runtime resume of given device.
 661  * @dev: Device to resume.
 662  * @rpmflags: Flag bits.
 663  *
 664  * Check if the device's runtime PM status allows it to be resumed.  Cancel
 665  * any scheduled or pending requests.  If another resume has been started
 666  * earlier, either return immediately or wait for it to finish, depending on the
 667  * RPM_NOWAIT and RPM_ASYNC flags.  Similarly, if there's a suspend running in
 668  * parallel with this function, either tell the other process to resume after
 669  * suspending (deferred_resume) or wait for it to finish.  If the RPM_ASYNC
 670  * flag is set then queue a resume request; otherwise run the
 671  * ->runtime_resume() callback directly.  Queue an idle notification for the
 672  * device if the resume succeeded.
 673  *
 674  * This function must be called under dev->power.lock with interrupts disabled.
 675  */
 676 static int rpm_resume(struct device *dev, int rpmflags)
 677         __releases(&dev->power.lock) __acquires(&dev->power.lock)
 678 {
 679         int (*callback)(struct device *);
 680         struct device *parent = NULL;
 681         int retval = 0;
 682
 683         trace_rpm_resume_rcuidle(dev, rpmflags);
 684
 685  repeat:
 686         if (dev->power.runtime_error)
 687                 retval = -EINVAL;
 688         else if (dev->power.disable_depth == 1 && dev->power.is_suspended
 689             && dev->power.runtime_status == RPM_ACTIVE)
 690                 retval = 1;
 691         else if (dev->power.disable_depth > 0)
 692                 retval = -EACCES;
 693         if (retval)
 694                 goto out;
 695
 696         /*
 697          * Other scheduled or pending requests need to be canceled.  Small
 698          * optimization: If an autosuspend timer is running, leave it running
 699          * rather than cancelling it now only to restart it again in the near
 700          * future.
 701          */
 702         dev->power.request = RPM_REQ_NONE;
 703         if (!dev->power.timer_autosuspends)
 704                 pm_runtime_deactivate_timer(dev);
 705
 706         if (dev->power.runtime_status == RPM_ACTIVE) {
 707                 retval = 1;
 708                 goto out;
 709         }
 710
 711         if (dev->power.runtime_status == RPM_RESUMING
 712             || dev->power.runtime_status == RPM_SUSPENDING) {
 713                 DEFINE_WAIT(wait);
 714
 715                 if (rpmflags & (RPM_ASYNC | RPM_NOWAIT)) {
 716                         if (dev->power.runtime_status == RPM_SUSPENDING)
 717                                 dev->power.deferred_resume = true;
 718                         else
 719                                 retval = -EINPROGRESS;
 720                         goto out;
 721                 }
 722
 723                 if (dev->power.irq_safe) {
 724                         spin_unlock(&dev->power.lock);
 725
 726                         cpu_relax();
 727
 728                         spin_lock(&dev->power.lock);
 729                         goto repeat;
 730                 }
 731
 732                 /* Wait for the operation carried out in parallel with us. */
 733                 for (;;) {
 734                         prepare_to_wait(&dev->power.wait_queue, &wait,
 735                                         TASK_UNINTERRUPTIBLE);
 736                         if (dev->power.runtime_status != RPM_RESUMING
 737                             && dev->power.runtime_status != RPM_SUSPENDING)
 738                                 break;
 739
 740                         spin_unlock_irq(&dev->power.lock);
 741
 742                         schedule();
 743
 744                         spin_lock_irq(&dev->power.lock);
 745                 }
 746                 finish_wait(&dev->power.wait_queue, &wait);
 747                 goto repeat;
 748         }
 749
 750         /*
 751          * See if we can skip waking up the parent.  This is safe only if
 752          * power.no_callbacks is set, because otherwise we don't know whether
 753          * the resume will actually succeed.
 754          */
 755         if (dev->power.no_callbacks && !parent && dev->parent) {
 756                 spin_lock_nested(&dev->parent->power.lock, SINGLE_DEPTH_NESTING);
 757                 if (dev->parent->power.disable_depth > 0
 758                     || dev->parent->power.ignore_children
 759                     || dev->parent->power.runtime_status == RPM_ACTIVE) {
 760                         atomic_inc(&dev->parent->power.child_count);
 761                         spin_unlock(&dev->parent->power.lock);
 762                         retval = 1;
 763                         goto no_callback;       /* Assume success. */
 764                 }
 765                 spin_unlock(&dev->parent->power.lock);
 766         }
 767
 768         /* Carry out an asynchronous or a synchronous resume. */
 769         if (rpmflags & RPM_ASYNC) {
 770                 dev->power.request = RPM_REQ_RESUME;
 771                 if (!dev->power.request_pending) {
 772                         dev->power.request_pending = true;
 773                         queue_work(pm_wq, &dev->power.work);
 774                 }
 775                 retval = 0;
 776                 goto out;
 777         }
 778
 779         if (!parent && dev->parent) {
 780                 /*
 781                  * Increment the parent's usage counter and resume it if
 782                  * necessary.  Not needed if dev is irq-safe; then the
 783                  * parent is permanently resumed.
 784                  */
 785                 parent = dev->parent;
 786                 if (dev->power.irq_safe)
 787                         goto skip_parent;
 788                 spin_unlock(&dev->power.lock);
 789
 790                 pm_runtime_get_noresume(parent);
 791
 792                 spin_lock(&parent->power.lock);
 793                 /*
 794                  * Resume the parent if it has runtime PM enabled and not been
 795                  * set to ignore its children.
 796                  */
 797                 if (!parent->power.disable_depth
 798                     && !parent->power.ignore_children) {
 799                         rpm_resume(parent, 0);
 800                         if (parent->power.runtime_status != RPM_ACTIVE)
 801                                 retval = -EBUSY;
 802                 }
 803                 spin_unlock(&parent->power.lock);
 804
 805                 spin_lock(&dev->power.lock);
 806                 if (retval)
 807                         goto out;
 808                 goto repeat;
 809         }
 810  skip_parent:
 811
 812         if (dev->power.no_callbacks)
 813                 goto no_callback;       /* Assume success. */
 814
 815         __update_runtime_status(dev, RPM_RESUMING);
 816
 817         callback = RPM_GET_CALLBACK(dev, runtime_resume);
 818
 819         dev_pm_disable_wake_irq_check(dev);
 820         retval = rpm_callback(callback, dev);
 821         if (retval) {
 822                 __update_runtime_status(dev, RPM_SUSPENDED);
 823                 pm_runtime_cancel_pending(dev);
 824                 dev_pm_enable_wake_irq_check(dev, false);
 825         } else {
 826  no_callback:
 827                 __update_runtime_status(dev, RPM_ACTIVE);
 828                 pm_runtime_mark_last_busy(dev);
 829                 if (parent)
 830                         atomic_inc(&parent->power.child_count);
 831         }
 832         wake_up_all(&dev->power.wait_queue);
 833
 834         if (retval >= 0)
 835                 rpm_idle(dev, RPM_ASYNC);
 836
 837  out:
 838         if (parent && !dev->power.irq_safe) {
 839                 spin_unlock_irq(&dev->power.lock);
 840
 841                 pm_runtime_put(parent);
 842
 843                 spin_lock_irq(&dev->power.lock);
 844         }
 845
 846         trace_rpm_return_int_rcuidle(dev, _THIS_IP_, retval);
 847
 848         return retval;
 849 }
 850
 851 /**
 852  * pm_runtime_work - Universal runtime PM work function.
 853  * @work: Work structure used for scheduling the execution of this function.
 854  *
 855  * Use @work to get the device object the work is to be done for, determine what
 856  * is to be done and execute the appropriate runtime PM function.
 857  */
 858 static void pm_runtime_work(struct work_struct *work)
 859 {
 860         struct device *dev = container_of(work, struct device, power.work);
 861         enum rpm_request req;
 862
 863         spin_lock_irq(&dev->power.lock);
 864
 865         if (!dev->power.request_pending)
 866                 goto out;
 867
 868         req = dev->power.request;
 869         dev->power.request = RPM_REQ_NONE;
 870         dev->power.request_pending = false;
 871
 872         switch (req) {
 873         case RPM_REQ_NONE:
 874                 break;
 875         case RPM_REQ_IDLE:
 876                 rpm_idle(dev, RPM_NOWAIT);
 877                 break;
 878         case RPM_REQ_SUSPEND:
 879                 rpm_suspend(dev, RPM_NOWAIT);
 880                 break;
 881         case RPM_REQ_AUTOSUSPEND:
 882                 rpm_suspend(dev, RPM_NOWAIT | RPM_AUTO);
 883                 break;
 884         case RPM_REQ_RESUME:
 885                 rpm_resume(dev, RPM_NOWAIT);
 886                 break;
 887         }
 888
 889  out:
 890         spin_unlock_irq(&dev->power.lock);
 891 }
 892
 893 /**
 894  * pm_suspend_timer_fn - Timer function for pm_schedule_suspend().
 895  * @data: Device pointer passed by pm_schedule_suspend().
 896  *
 897  * Check if the time is right and queue a suspend request.
 898  */
 899 static enum hrtimer_restart  pm_suspend_timer_fn(struct hrtimer *timer)
 900 {
 901         struct device *dev = container_of(timer, struct device, power.suspend_timer);
 902         unsigned long flags;
 903         u64 expires;
 904
 905         spin_lock_irqsave(&dev->power.lock, flags);
 906
 907         expires = dev->power.timer_expires;
 908         /* If 'expire' is after 'jiffies' we've been called too early. */
 909         if (expires > 0 && expires < ktime_to_ns(ktime_get())) {
 910                 dev->power.timer_expires = 0;
 911                 rpm_suspend(dev, dev->power.timer_autosuspends ?
 912                     (RPM_ASYNC | RPM_AUTO) : RPM_ASYNC);
 913         }
 914
 915         spin_unlock_irqrestore(&dev->power.lock, flags);
 916
 917         return HRTIMER_NORESTART;
 918 }
 919
 920 /**
 921  * pm_schedule_suspend - Set up a timer to submit a suspend request in future.
 922  * @dev: Device to suspend.
 923  * @delay: Time to wait before submitting a suspend request, in milliseconds.
 924  */
 925 int pm_schedule_suspend(struct device *dev, unsigned int delay)
 926 {
 927         unsigned long flags;
 928         ktime_t expires;
 929         int retval;
 930
 931         spin_lock_irqsave(&dev->power.lock, flags);
 932
 933         if (!delay) {
 934                 retval = rpm_suspend(dev, RPM_ASYNC);
 935                 goto out;
 936         }
 937
 938         retval = rpm_check_suspend_allowed(dev);
 939         if (retval)
 940                 goto out;
 941
 942         /* Other scheduled or pending requests need to be canceled. */
 943         pm_runtime_cancel_pending(dev);
 944
 945         expires = ktime_add(ktime_get(), ms_to_ktime(delay));
 946         dev->power.timer_expires = ktime_to_ns(expires);
 947         dev->power.timer_autosuspends = 0;
 948         hrtimer_start(&dev->power.suspend_timer, expires, HRTIMER_MODE_ABS);
 949
 950  out:
 951         spin_unlock_irqrestore(&dev->power.lock, flags);
 952
 953         return retval;
 954 }
 955 EXPORT_SYMBOL_GPL(pm_schedule_suspend);
 956
 957 /**
 958  * __pm_runtime_idle - Entry point for runtime idle operations.
 959  * @dev: Device to send idle notification for.
 960  * @rpmflags: Flag bits.
 961  *
 962  * If the RPM_GET_PUT flag is set, decrement the device's usage count and
 963  * return immediately if it is larger than zero.  Then carry out an idle
 964  * notification, either synchronous or asynchronous.
 965  *
 966  * This routine may be called in atomic context if the RPM_ASYNC flag is set,
 967  * or if pm_runtime_irq_safe() has been called.
 968  */
 969 int __pm_runtime_idle(struct device *dev, int rpmflags)
 970 {
 971         unsigned long flags;
 972         int retval;
 973
 974         if (rpmflags & RPM_GET_PUT) {
 975                 if (!atomic_dec_and_test(&dev->power.usage_count))
 976                         return 0;
 977         }
 978
 979         might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);
 980
 981         spin_lock_irqsave(&dev->power.lock, flags);
 982         retval = rpm_idle(dev, rpmflags);
 983         spin_unlock_irqrestore(&dev->power.lock, flags);
 984
 985         return retval;
 986 }
 987 EXPORT_SYMBOL_GPL(__pm_runtime_idle);
 988
 989 /**
 990  * __pm_runtime_suspend - Entry point for runtime put/suspend operations.
 991  * @dev: Device to suspend.
 992  * @rpmflags: Flag bits.
 993  *
 994  * If the RPM_GET_PUT flag is set, decrement the device's usage count and
 995  * return immediately if it is larger than zero.  Then carry out a suspend,
 996  * either synchronous or asynchronous.
 997  *
 998  * This routine may be called in atomic context if the RPM_ASYNC flag is set,
 999  * or if pm_runtime_irq_safe() has been called.
1000  */
1001 int __pm_runtime_suspend(struct device *dev, int rpmflags)
1002 {
1003         unsigned long flags;
1004         int retval;
1005
1006         if (rpmflags & RPM_GET_PUT) {
1007                 if (!atomic_dec_and_test(&dev->power.usage_count))
1008                         return 0;
1009         }
1010
1011         might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);
1012
1013         spin_lock_irqsave(&dev->power.lock, flags);
1014         retval = rpm_suspend(dev, rpmflags);
1015         spin_unlock_irqrestore(&dev->power.lock, flags);
1016
1017         return retval;
1018 }
1019 EXPORT_SYMBOL_GPL(__pm_runtime_suspend);
1020
1021 /**
1022  * __pm_runtime_resume - Entry point for runtime resume operations.
1023  * @dev: Device to resume.
1024  * @rpmflags: Flag bits.
1025  *
1026  * If the RPM_GET_PUT flag is set, increment the device's usage count.  Then
1027  * carry out a resume, either synchronous or asynchronous.
1028  *
1029  * This routine may be called in atomic context if the RPM_ASYNC flag is set,
1030  * or if pm_runtime_irq_safe() has been called.
1031  */
1032 int __pm_runtime_resume(struct device *dev, int rpmflags)
1033 {
1034         unsigned long flags;
1035         int retval;
1036
1037         might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe &&
1038                         dev->power.runtime_status != RPM_ACTIVE);
1039
1040         if (rpmflags & RPM_GET_PUT)
1041                 atomic_inc(&dev->power.usage_count);
1042
1043         spin_lock_irqsave(&dev->power.lock, flags);
1044         retval = rpm_resume(dev, rpmflags);
1045         spin_unlock_irqrestore(&dev->power.lock, flags);
1046
1047         return retval;
1048 }
1049 EXPORT_SYMBOL_GPL(__pm_runtime_resume);
1050
1051 /**
1052  * pm_runtime_get_if_in_use - Conditionally bump up the device's usage counter.
1053  * @dev: Device to handle.
1054  *
1055  * Return -EINVAL if runtime PM is disabled for the device.
1056  *
1057  * If that's not the case and if the device's runtime PM status is RPM_ACTIVE
1058  * and the runtime PM usage counter is nonzero, increment the counter and
1059  * return 1.  Otherwise return 0 without changing the counter.
1060  */
1061 int pm_runtime_get_if_in_use(struct device *dev)
1062 {
1063         unsigned long flags;
1064         int retval;
1065
1066         spin_lock_irqsave(&dev->power.lock, flags);
1067         retval = dev->power.disable_depth > 0 ? -EINVAL :
1068                 dev->power.runtime_status == RPM_ACTIVE
1069                         && atomic_inc_not_zero(&dev->power.usage_count);
1070         spin_unlock_irqrestore(&dev->power.lock, flags);
1071         return retval;
1072 }
1073 EXPORT_SYMBOL_GPL(pm_runtime_get_if_in_use);
1074
1075 /**
1076  * __pm_runtime_set_status - Set runtime PM status of a device.
1077  * @dev: Device to handle.
1078  * @status: New runtime PM status of the device.
1079  *
1080  * If runtime PM of the device is disabled or its power.runtime_error field is
1081  * different from zero, the status may be changed either to RPM_ACTIVE, or to
1082  * RPM_SUSPENDED, as long as that reflects the actual state of the device.
1083  * However, if the device has a parent and the parent is not active, and the
1084  * parent's power.ignore_children flag is unset, the device's status cannot be
1085  * set to RPM_ACTIVE, so -EBUSY is returned in that case.
1086  *
1087  * If successful, __pm_runtime_set_status() clears the power.runtime_error field
1088  * and the device parent's counter of unsuspended children is modified to
1089  * reflect the new status.  If the new status is RPM_SUSPENDED, an idle
1090  * notification request for the parent is submitted.
1091  */
1092 int __pm_runtime_set_status(struct device *dev, unsigned int status)
1093 {
1094         struct device *parent = dev->parent;
1095         unsigned long flags;
1096         bool notify_parent = false;
1097         int error = 0;
1098
1099         if (status != RPM_ACTIVE && status != RPM_SUSPENDED)
1100                 return -EINVAL;
1101
1102         spin_lock_irqsave(&dev->power.lock, flags);
1103
1104         if (!dev->power.runtime_error && !dev->power.disable_depth) {
1105                 error = -EAGAIN;
1106                 goto out;
1107         }
1108
1109         if (dev->power.runtime_status == status || !parent)
1110                 goto out_set;
1111
1112         if (status == RPM_SUSPENDED) {
1113                 atomic_add_unless(&parent->power.child_count, -1, 0);
1114                 notify_parent = !parent->power.ignore_children;
1115         } else {
1116                 spin_lock_nested(&parent->power.lock, SINGLE_DEPTH_NESTING);
1117
1118                 /*
1119                  * It is invalid to put an active child under a parent that is
1120                  * not active, has runtime PM enabled and the
1121                  * 'power.ignore_children' flag unset.
1122                  */
1123                 if (!parent->power.disable_depth
1124                     && !parent->power.ignore_children
1125                     && parent->power.runtime_status != RPM_ACTIVE) {
1126                         dev_err(dev, "runtime PM trying to activate child device %s but parent (%s) is not active\n",
1127                                 dev_name(dev),
1128                                 dev_name(parent));
1129                         error = -EBUSY;
1130                 } else if (dev->power.runtime_status == RPM_SUSPENDED) {
1131                         atomic_inc(&parent->power.child_count);
1132                 }
1133
1134                 spin_unlock(&parent->power.lock);
1135
1136                 if (error)
1137                         goto out;
1138         }
1139
1140  out_set:
1141         __update_runtime_status(dev, status);
1142         dev->power.runtime_error = 0;
1143  out:
1144         spin_unlock_irqrestore(&dev->power.lock, flags);
1145
1146         if (notify_parent)
1147                 pm_request_idle(parent);
1148
1149         return error;
1150 }
1151 EXPORT_SYMBOL_GPL(__pm_runtime_set_status);
1152
1153 /**
1154  * __pm_runtime_barrier - Cancel pending requests and wait for completions.
1155  * @dev: Device to handle.
1156  *
1157  * Flush all pending requests for the device from pm_wq and wait for all
1158  * runtime PM operations involving the device in progress to complete.
1159  *
1160  * Should be called under dev->power.lock with interrupts disabled.
1161  */
1162 static void __pm_runtime_barrier(struct device *dev)
1163 {
1164         pm_runtime_deactivate_timer(dev);
1165
1166         if (dev->power.request_pending) {
1167                 dev->power.request = RPM_REQ_NONE;
1168                 spin_unlock_irq(&dev->power.lock);
1169
1170                 cancel_work_sync(&dev->power.work);
1171
1172                 spin_lock_irq(&dev->power.lock);
1173                 dev->power.request_pending = false;
1174         }
1175
1176         if (dev->power.runtime_status == RPM_SUSPENDING
1177             || dev->power.runtime_status == RPM_RESUMING
1178             || dev->power.idle_notification) {
1179                 DEFINE_WAIT(wait);
1180
1181                 /* Suspend, wake-up or idle notification in progress. */
1182                 for (;;) {
1183                         prepare_to_wait(&dev->power.wait_queue, &wait,
1184                                         TASK_UNINTERRUPTIBLE);
1185                         if (dev->power.runtime_status != RPM_SUSPENDING
1186                             && dev->power.runtime_status != RPM_RESUMING
1187                             && !dev->power.idle_notification)
1188                                 break;
1189                         spin_unlock_irq(&dev->power.lock);
1190
1191                         schedule();
1192
1193                         spin_lock_irq(&dev->power.lock);
1194                 }
1195                 finish_wait(&dev->power.wait_queue, &wait);
1196         }
1197 }
1198
1199 /**
1200  * pm_runtime_barrier - Flush pending requests and wait for completions.
1201  * @dev: Device to handle.
1202  *
1203  * Prevent the device from being suspended by incrementing its usage counter and
1204  * if there's a pending resume request for the device, wake the device up.
1205  * Next, make sure that all pending requests for the device have been flushed
1206  * from pm_wq and wait for all runtime PM operations involving the device in
1207  * progress to complete.
1208  *
1209  * Return value:
1210  * 1, if there was a resume request pending and the device had to be woken up,
1211  * 0, otherwise
1212  */
1213 int pm_runtime_barrier(struct device *dev)
1214 {
1215         int retval = 0;
1216
1217         pm_runtime_get_noresume(dev);
1218         spin_lock_irq(&dev->power.lock);
1219
1220         if (dev->power.request_pending
1221             && dev->power.request == RPM_REQ_RESUME) {
1222                 rpm_resume(dev, 0);
1223                 retval = 1;
1224         }
1225
1226         __pm_runtime_barrier(dev);
1227
1228         spin_unlock_irq(&dev->power.lock);
1229         pm_runtime_put_noidle(dev);
1230
1231         return retval;
1232 }
1233 EXPORT_SYMBOL_GPL(pm_runtime_barrier);
1234
1235 /**
1236  * __pm_runtime_disable - Disable runtime PM of a device.
1237  * @dev: Device to handle.
1238  * @check_resume: If set, check if there's a resume request for the device.
1239  *
1240  * Increment power.disable_depth for the device and if it was zero previously,
1241  * cancel all pending runtime PM requests for the device and wait for all
1242  * operations in progress to complete.  The device can be either active or
1243  * suspended after its runtime PM has been disabled.
1244  *
1245  * If @check_resume is set and there's a resume request pending when
1246  * __pm_runtime_disable() is called and power.disable_depth is zero, the
1247  * function will wake up the device before disabling its runtime PM.
1248  */
1249 void __pm_runtime_disable(struct device *dev, bool check_resume)
1250 {
1251         spin_lock_irq(&dev->power.lock);
1252
1253         if (dev->power.disable_depth > 0) {
1254                 dev->power.disable_depth++;
1255                 goto out;
1256         }
1257
1258         /*
1259          * Wake up the device if there's a resume request pending, because that
1260          * means there probably is some I/O to process and disabling runtime PM
1261          * shouldn't prevent the device from processing the I/O.
1262          */
1263         if (check_resume && dev->power.request_pending
1264             && dev->power.request == RPM_REQ_RESUME) {
1265                 /*
1266                  * Prevent suspends and idle notifications from being carried
1267                  * out after we have woken up the device.
1268                  */
1269                 pm_runtime_get_noresume(dev);
1270
1271                 rpm_resume(dev, 0);
1272
1273                 pm_runtime_put_noidle(dev);
1274         }
1275
1276         if (!dev->power.disable_depth++)
1277                 __pm_runtime_barrier(dev);
1278
1279  out:
1280         spin_unlock_irq(&dev->power.lock);
1281 }
1282 EXPORT_SYMBOL_GPL(__pm_runtime_disable);
1283
1284 /**
1285  * pm_runtime_enable - Enable runtime PM of a device.
1286  * @dev: Device to handle.
1287  */
1288 void pm_runtime_enable(struct device *dev)
1289 {
1290         unsigned long flags;
1291
1292         spin_lock_irqsave(&dev->power.lock, flags);
1293
1294         if (dev->power.disable_depth > 0)
1295                 dev->power.disable_depth--;
1296         else
1297                 dev_warn(dev, "Unbalanced %s!\n", __func__);
1298
1299         WARN(!dev->power.disable_depth &&
1300              dev->power.runtime_status == RPM_SUSPENDED &&
1301              !dev->power.ignore_children &&
1302              atomic_read(&dev->power.child_count) > 0,
1303              "Enabling runtime PM for inactive device (%s) with active children\n",
1304              dev_name(dev));
1305
1306         spin_unlock_irqrestore(&dev->power.lock, flags);
1307 }
1308 EXPORT_SYMBOL_GPL(pm_runtime_enable);
1309
1310 /**
1311  * pm_runtime_forbid - Block runtime PM of a device.
1312  * @dev: Device to handle.
1313  *
1314  * Increase the device's usage count and clear its power.runtime_auto flag,
1315  * so that it cannot be suspended at run time until pm_runtime_allow() is called
1316  * for it.
1317  */
1318 void pm_runtime_forbid(struct device *dev)
1319 {
1320         spin_lock_irq(&dev->power.lock);
1321         if (!dev->power.runtime_auto)
1322                 goto out;
1323
1324         dev->power.runtime_auto = false;
1325         atomic_inc(&dev->power.usage_count);
1326         rpm_resume(dev, 0);
1327
1328  out:
1329         spin_unlock_irq(&dev->power.lock);
1330 }
1331 EXPORT_SYMBOL_GPL(pm_runtime_forbid);
1332
1333 /**
1334  * pm_runtime_allow - Unblock runtime PM of a device.
1335  * @dev: Device to handle.
1336  *
1337  * Decrease the device's usage count and set its power.runtime_auto flag.
1338  */
1339 void pm_runtime_allow(struct device *dev)
1340 {
1341         spin_lock_irq(&dev->power.lock);
1342         if (dev->power.runtime_auto)
1343                 goto out;
1344
1345         dev->power.runtime_auto = true;
1346         if (atomic_dec_and_test(&dev->power.usage_count))
1347                 rpm_idle(dev, RPM_AUTO | RPM_ASYNC);
1348
1349  out:
1350         spin_unlock_irq(&dev->power.lock);
1351 }
1352 EXPORT_SYMBOL_GPL(pm_runtime_allow);
1353
1354 /**
1355  * pm_runtime_no_callbacks - Ignore runtime PM callbacks for a device.
1356  * @dev: Device to handle.
1357  *
1358  * Set the power.no_callbacks flag, which tells the PM core that this
1359  * device is power-managed through its parent and has no runtime PM
1360  * callbacks of its own.  The runtime sysfs attributes will be removed.
1361  */
1362 void pm_runtime_no_callbacks(struct device *dev)
1363 {
1364         spin_lock_irq(&dev->power.lock);
1365         dev->power.no_callbacks = 1;
1366         spin_unlock_irq(&dev->power.lock);
1367         if (device_is_registered(dev))
1368                 rpm_sysfs_remove(dev);
1369 }
1370 EXPORT_SYMBOL_GPL(pm_runtime_no_callbacks);
1371
1372 /**
1373  * pm_runtime_irq_safe - Leave interrupts disabled during callbacks.
1374  * @dev: Device to handle
1375  *
1376  * Set the power.irq_safe flag, which tells the PM core that the
1377  * ->runtime_suspend() and ->runtime_resume() callbacks for this device should
1378  * always be invoked with the spinlock held and interrupts disabled.  It also
1379  * causes the parent's usage counter to be permanently incremented, preventing
1380  * the parent from runtime suspending -- otherwise an irq-safe child might have
1381  * to wait for a non-irq-safe parent.
1382  */
1383 void pm_runtime_irq_safe(struct device *dev)
1384 {
1385         if (dev->parent)
1386                 pm_runtime_get_sync(dev->parent);
1387         spin_lock_irq(&dev->power.lock);
1388         dev->power.irq_safe = 1;
1389         spin_unlock_irq(&dev->power.lock);
1390 }
1391 EXPORT_SYMBOL_GPL(pm_runtime_irq_safe);
1392
1393 /**
1394  * update_autosuspend - Handle a change to a device's autosuspend settings.
1395  * @dev: Device to handle.
1396  * @old_delay: The former autosuspend_delay value.
1397  * @old_use: The former use_autosuspend value.
1398  *
1399  * Prevent runtime suspend if the new delay is negative and use_autosuspend is
1400  * set; otherwise allow it.  Send an idle notification if suspends are allowed.
1401  *
1402  * This function must be called under dev->power.lock with interrupts disabled.
1403  */
1404 static void update_autosuspend(struct device *dev, int old_delay, int old_use)
1405 {
1406         int delay = dev->power.autosuspend_delay;
1407
1408         /* Should runtime suspend be prevented now? */
1409         if (dev->power.use_autosuspend && delay < 0) {
1410
1411                 /* If it used to be allowed then prevent it. */
1412                 if (!old_use || old_delay >= 0) {
1413                         atomic_inc(&dev->power.usage_count);
1414                         rpm_resume(dev, 0);
1415                 }
1416         }
1417
1418         /* Runtime suspend should be allowed now. */
1419         else {
1420
1421                 /* If it used to be prevented then allow it. */
1422                 if (old_use && old_delay < 0)
1423                         atomic_dec(&dev->power.usage_count);
1424
1425                 /* Maybe we can autosuspend now. */
1426                 rpm_idle(dev, RPM_AUTO);
1427         }
1428 }
1429
1430 /**
1431  * pm_runtime_set_autosuspend_delay - Set a device's autosuspend_delay value.
1432  * @dev: Device to handle.
1433  * @delay: Value of the new delay in milliseconds.
1434  *
1435  * Set the device's power.autosuspend_delay value.  If it changes to negative
1436  * and the power.use_autosuspend flag is set, prevent runtime suspends.  If it
1437  * changes the other way, allow runtime suspends.
1438  */
1439 void pm_runtime_set_autosuspend_delay(struct device *dev, int delay)
1440 {
1441         int old_delay, old_use;
1442
1443         spin_lock_irq(&dev->power.lock);
1444         old_delay = dev->power.autosuspend_delay;
1445         old_use = dev->power.use_autosuspend;
1446         dev->power.autosuspend_delay = delay;
1447         update_autosuspend(dev, old_delay, old_use);
1448         spin_unlock_irq(&dev->power.lock);
1449 }
1450 EXPORT_SYMBOL_GPL(pm_runtime_set_autosuspend_delay);
1451
1452 /**
1453  * __pm_runtime_use_autosuspend - Set a device's use_autosuspend flag.
1454  * @dev: Device to handle.
1455  * @use: New value for use_autosuspend.
1456  *
1457  * Set the device's power.use_autosuspend flag, and allow or prevent runtime
1458  * suspends as needed.
1459  */
1460 void __pm_runtime_use_autosuspend(struct device *dev, bool use)
1461 {
1462         int old_delay, old_use;
1463
1464         spin_lock_irq(&dev->power.lock);
1465         old_delay = dev->power.autosuspend_delay;
1466         old_use = dev->power.use_autosuspend;
1467         dev->power.use_autosuspend = use;
1468         update_autosuspend(dev, old_delay, old_use);
1469         spin_unlock_irq(&dev->power.lock);
1470 }
1471 EXPORT_SYMBOL_GPL(__pm_runtime_use_autosuspend);
1472
1473 /**
1474  * pm_runtime_init - Initialize runtime PM fields in given device object.
1475  * @dev: Device object to initialize.
1476  */
1477 void pm_runtime_init(struct device *dev)
1478 {
1479         dev->power.runtime_status = RPM_SUSPENDED;
1480         dev->power.idle_notification = false;
1481
1482         dev->power.disable_depth = 1;
1483         atomic_set(&dev->power.usage_count, 0);
1484
1485         dev->power.runtime_error = 0;
1486
1487         atomic_set(&dev->power.child_count, 0);
1488         pm_suspend_ignore_children(dev, false);
1489         dev->power.runtime_auto = true;
1490
1491         dev->power.request_pending = false;
1492         dev->power.request = RPM_REQ_NONE;
1493         dev->power.deferred_resume = false;
1494         dev->power.accounting_timestamp = jiffies;
1495         INIT_WORK(&dev->power.work, pm_runtime_work);
1496
1497         dev->power.timer_expires = 0;
1498         hrtimer_init(&dev->power.suspend_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
1499         dev->power.suspend_timer.function = pm_suspend_timer_fn;
1500
1501         init_waitqueue_head(&dev->power.wait_queue);
1502 }
1503
1504 /**
1505  * pm_runtime_reinit - Re-initialize runtime PM fields in given device object.
1506  * @dev: Device object to re-initialize.
1507  */
1508 void pm_runtime_reinit(struct device *dev)
1509 {
1510         if (!pm_runtime_enabled(dev)) {
1511                 if (dev->power.runtime_status == RPM_ACTIVE)
1512                         pm_runtime_set_suspended(dev);
1513                 if (dev->power.irq_safe) {
1514                         spin_lock_irq(&dev->power.lock);
1515                         dev->power.irq_safe = 0;
1516                         spin_unlock_irq(&dev->power.lock);
1517                         if (dev->parent)
1518                                 pm_runtime_put(dev->parent);
1519                 }
1520         }
1521 }
1522
1523 /**
1524  * pm_runtime_remove - Prepare for removing a device from device hierarchy.
1525  * @dev: Device object being removed from device hierarchy.
1526  */
1527 void pm_runtime_remove(struct device *dev)
1528 {
1529         __pm_runtime_disable(dev, false);
1530         pm_runtime_reinit(dev);
1531 }
1532
1533 /**
1534  * pm_runtime_clean_up_links - Prepare links to consumers for driver removal.
1535  * @dev: Device whose driver is going to be removed.
1536  *
1537  * Check links from this device to any consumers and if any of them have active
1538  * runtime PM references to the device, drop the usage counter of the device
1539  * (once per link).
1540  *
1541  * Links with the DL_FLAG_STATELESS flag set are ignored.
1542  *
1543  * Since the device is guaranteed to be runtime-active at the point this is
1544  * called, nothing else needs to be done here.
1545  *
1546  * Moreover, this is called after device_links_busy() has returned 'false', so
1547  * the status of each link is guaranteed to be DL_STATE_SUPPLIER_UNBIND and
1548  * therefore rpm_active can't be manipulated concurrently.
1549  */
1550 void pm_runtime_clean_up_links(struct device *dev)
1551 {
1552         struct device_link *link;
1553         int idx;
1554
1555         idx = device_links_read_lock();
1556
1557         list_for_each_entry_rcu(link, &dev->links.consumers, s_node) {
1558                 if (link->flags & DL_FLAG_STATELESS)
1559                         continue;
1560
1561                 if (link->rpm_active) {
1562                         pm_runtime_put_noidle(dev);
1563                         link->rpm_active = false;
1564                 }
1565         }
1566
1567         device_links_read_unlock(idx);
1568 }
1569
1570 /**
1571  * pm_runtime_get_suppliers - Resume and reference-count supplier devices.
1572  * @dev: Consumer device.
1573  */
1574 void pm_runtime_get_suppliers(struct device *dev)
1575 {
1576         struct device_link *link;
1577         int idx;
1578
1579         idx = device_links_read_lock();
1580
1581         list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
1582                 if (link->flags & DL_FLAG_PM_RUNTIME)
1583                         pm_runtime_get_sync(link->supplier);
1584
1585         device_links_read_unlock(idx);
1586 }
1587
1588 /**
1589  * pm_runtime_put_suppliers - Drop references to supplier devices.
1590  * @dev: Consumer device.
1591  */
1592 void pm_runtime_put_suppliers(struct device *dev)
1593 {
1594         struct device_link *link;
1595         int idx;
1596
1597         idx = device_links_read_lock();
1598
1599         list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
1600                 if (link->flags & DL_FLAG_PM_RUNTIME)
1601                         pm_runtime_put(link->supplier);
1602
1603         device_links_read_unlock(idx);
1604 }
1605
1606 void pm_runtime_new_link(struct device *dev)
1607 {
1608         spin_lock_irq(&dev->power.lock);
1609         dev->power.links_count++;
1610         spin_unlock_irq(&dev->power.lock);
1611 }
1612
1613 void pm_runtime_drop_link(struct device *dev)
1614 {
1615         rpm_put_suppliers(dev);
1616
1617         spin_lock_irq(&dev->power.lock);
1618         WARN_ON(dev->power.links_count == 0);
1619         dev->power.links_count--;
1620         spin_unlock_irq(&dev->power.lock);
1621 }
1622
1623 static bool pm_runtime_need_not_resume(struct device *dev)
1624 {
1625         return atomic_read(&dev->power.usage_count) <= 1 &&
1626                 (atomic_read(&dev->power.child_count) == 0 ||
1627                  dev->power.ignore_children);
1628 }
1629
1630 /**
1631  * pm_runtime_force_suspend - Force a device into suspend state if needed.
1632  * @dev: Device to suspend.
1633  *
1634  * Disable runtime PM so we safely can check the device's runtime PM status and
1635  * if it is active, invoke its ->runtime_suspend callback to suspend it and
1636  * change its runtime PM status field to RPM_SUSPENDED.  Also, if the device's
1637  * usage and children counters don't indicate that the device was in use before
1638  * the system-wide transition under way, decrement its parent's children counter
1639  * (if there is a parent).  Keep runtime PM disabled to preserve the state
1640  * unless we encounter errors.
1641  *
1642  * Typically this function may be invoked from a system suspend callback to make
1643  * sure the device is put into low power state and it should only be used during
1644  * system-wide PM transitions to sleep states.  It assumes that the analogous
1645  * pm_runtime_force_resume() will be used to resume the device.
1646  */
1647 int pm_runtime_force_suspend(struct device *dev)
1648 {
1649         int (*callback)(struct device *);
1650         int ret;
1651
1652         pm_runtime_disable(dev);
1653         if (pm_runtime_status_suspended(dev))
1654                 return 0;
1655
1656         callback = RPM_GET_CALLBACK(dev, runtime_suspend);
1657
1658         ret = callback ? callback(dev) : 0;
1659         if (ret)
1660                 goto err;
1661
1662         /*
1663          * If the device can stay in suspend after the system-wide transition
1664          * to the working state that will follow, drop the children counter of
1665          * its parent, but set its status to RPM_SUSPENDED anyway in case this
1666          * function will be called again for it in the meantime.
1667          */
1668         if (pm_runtime_need_not_resume(dev))
1669                 pm_runtime_set_suspended(dev);
1670         else
1671                 __update_runtime_status(dev, RPM_SUSPENDED);
1672
1673         return 0;
1674
1675 err:
1676         pm_runtime_enable(dev);
1677         return ret;
1678 }
1679 EXPORT_SYMBOL_GPL(pm_runtime_force_suspend);
1680
1681 /**
1682  * pm_runtime_force_resume - Force a device into resume state if needed.
1683  * @dev: Device to resume.
1684  *
1685  * Prior invoking this function we expect the user to have brought the device
1686  * into low power state by a call to pm_runtime_force_suspend(). Here we reverse
1687  * those actions and bring the device into full power, if it is expected to be
1688  * used on system resume.  In the other case, we defer the resume to be managed
1689  * via runtime PM.
1690  *
1691  * Typically this function may be invoked from a system resume callback.
1692  */
1693 int pm_runtime_force_resume(struct device *dev)
1694 {
1695         int (*callback)(struct device *);
1696         int ret = 0;
1697
1698         if (!pm_runtime_status_suspended(dev) || pm_runtime_need_not_resume(dev))
1699                 goto out;
1700
1701         /*
1702          * The value of the parent's children counter is correct already, so
1703          * just update the status of the device.
1704          */
1705         __update_runtime_status(dev, RPM_ACTIVE);
1706
1707         callback = RPM_GET_CALLBACK(dev, runtime_resume);
1708
1709         ret = callback ? callback(dev) : 0;
1710         if (ret) {
1711                 pm_runtime_set_suspended(dev);
1712                 goto out;
1713         }
1714
1715         pm_runtime_mark_last_busy(dev);
1716 out:
1717         pm_runtime_enable(dev);
1718         return ret;
1719 }
1720 EXPORT_SYMBOL_GPL(pm_runtime_force_resume);