linux/drivers/base/power/runtime.c
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   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * drivers/base/power/runtime.c - Helper functions for device runtime PM
   4 *
   5 * Copyright (c) 2009 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
   6 * Copyright (C) 2010 Alan Stern <stern@rowland.harvard.edu>
   7 */
   8#include <linux/sched/mm.h>
   9#include <linux/ktime.h>
  10#include <linux/hrtimer.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
  19typedef int (*pm_callback_t)(struct device *);
  20
  21static 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
  51static int rpm_resume(struct device *dev, int rpmflags);
  52static 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 */
  65static void update_pm_runtime_accounting(struct device *dev)
  66{
  67        u64 now, last, delta;
  68
  69        if (dev->power.disable_depth > 0)
  70                return;
  71
  72        last = dev->power.accounting_timestamp;
  73
  74        now = ktime_get_mono_fast_ns();
  75        dev->power.accounting_timestamp = now;
  76
  77        /*
  78         * Because ktime_get_mono_fast_ns() is not monotonic during
  79         * timekeeping updates, ensure that 'now' is after the last saved
  80         * timesptamp.
  81         */
  82        if (now < last)
  83                return;
  84
  85        delta = now - last;
  86
  87        if (dev->power.runtime_status == RPM_SUSPENDED)
  88                dev->power.suspended_time += delta;
  89        else
  90                dev->power.active_time += delta;
  91}
  92
  93static void __update_runtime_status(struct device *dev, enum rpm_status status)
  94{
  95        update_pm_runtime_accounting(dev);
  96        dev->power.runtime_status = status;
  97}
  98
  99static u64 rpm_get_accounted_time(struct device *dev, bool suspended)
 100{
 101        u64 time;
 102        unsigned long flags;
 103
 104        spin_lock_irqsave(&dev->power.lock, flags);
 105
 106        update_pm_runtime_accounting(dev);
 107        time = suspended ? dev->power.suspended_time : dev->power.active_time;
 108
 109        spin_unlock_irqrestore(&dev->power.lock, flags);
 110
 111        return time;
 112}
 113
 114u64 pm_runtime_active_time(struct device *dev)
 115{
 116        return rpm_get_accounted_time(dev, false);
 117}
 118
 119u64 pm_runtime_suspended_time(struct device *dev)
 120{
 121        return rpm_get_accounted_time(dev, true);
 122}
 123EXPORT_SYMBOL_GPL(pm_runtime_suspended_time);
 124
 125/**
 126 * pm_runtime_deactivate_timer - Deactivate given device's suspend timer.
 127 * @dev: Device to handle.
 128 */
 129static void pm_runtime_deactivate_timer(struct device *dev)
 130{
 131        if (dev->power.timer_expires > 0) {
 132                hrtimer_try_to_cancel(&dev->power.suspend_timer);
 133                dev->power.timer_expires = 0;
 134        }
 135}
 136
 137/**
 138 * pm_runtime_cancel_pending - Deactivate suspend timer and cancel requests.
 139 * @dev: Device to handle.
 140 */
 141static void pm_runtime_cancel_pending(struct device *dev)
 142{
 143        pm_runtime_deactivate_timer(dev);
 144        /*
 145         * In case there's a request pending, make sure its work function will
 146         * return without doing anything.
 147         */
 148        dev->power.request = RPM_REQ_NONE;
 149}
 150
 151/*
 152 * pm_runtime_autosuspend_expiration - Get a device's autosuspend-delay expiration time.
 153 * @dev: Device to handle.
 154 *
 155 * Compute the autosuspend-delay expiration time based on the device's
 156 * power.last_busy time.  If the delay has already expired or is disabled
 157 * (negative) or the power.use_autosuspend flag isn't set, return 0.
 158 * Otherwise return the expiration time in nanoseconds (adjusted to be nonzero).
 159 *
 160 * This function may be called either with or without dev->power.lock held.
 161 * Either way it can be racy, since power.last_busy may be updated at any time.
 162 */
 163u64 pm_runtime_autosuspend_expiration(struct device *dev)
 164{
 165        int autosuspend_delay;
 166        u64 expires;
 167
 168        if (!dev->power.use_autosuspend)
 169                return 0;
 170
 171        autosuspend_delay = READ_ONCE(dev->power.autosuspend_delay);
 172        if (autosuspend_delay < 0)
 173                return 0;
 174
 175        expires  = READ_ONCE(dev->power.last_busy);
 176        expires += (u64)autosuspend_delay * NSEC_PER_MSEC;
 177        if (expires > ktime_get_mono_fast_ns())
 178                return expires; /* Expires in the future */
 179
 180        return 0;
 181}
 182EXPORT_SYMBOL_GPL(pm_runtime_autosuspend_expiration);
 183
 184static int dev_memalloc_noio(struct device *dev, void *data)
 185{
 186        return dev->power.memalloc_noio;
 187}
 188
 189/*
 190 * pm_runtime_set_memalloc_noio - Set a device's memalloc_noio flag.
 191 * @dev: Device to handle.
 192 * @enable: True for setting the flag and False for clearing the flag.
 193 *
 194 * Set the flag for all devices in the path from the device to the
 195 * root device in the device tree if @enable is true, otherwise clear
 196 * the flag for devices in the path whose siblings don't set the flag.
 197 *
 198 * The function should only be called by block device, or network
 199 * device driver for solving the deadlock problem during runtime
 200 * resume/suspend:
 201 *
 202 *     If memory allocation with GFP_KERNEL is called inside runtime
 203 *     resume/suspend callback of any one of its ancestors(or the
 204 *     block device itself), the deadlock may be triggered inside the
 205 *     memory allocation since it might not complete until the block
 206 *     device becomes active and the involed page I/O finishes. The
 207 *     situation is pointed out first by Alan Stern. Network device
 208 *     are involved in iSCSI kind of situation.
 209 *
 210 * The lock of dev_hotplug_mutex is held in the function for handling
 211 * hotplug race because pm_runtime_set_memalloc_noio() may be called
 212 * in async probe().
 213 *
 214 * The function should be called between device_add() and device_del()
 215 * on the affected device(block/network device).
 216 */
 217void pm_runtime_set_memalloc_noio(struct device *dev, bool enable)
 218{
 219        static DEFINE_MUTEX(dev_hotplug_mutex);
 220
 221        mutex_lock(&dev_hotplug_mutex);
 222        for (;;) {
 223                bool enabled;
 224
 225                /* hold power lock since bitfield is not SMP-safe. */
 226                spin_lock_irq(&dev->power.lock);
 227                enabled = dev->power.memalloc_noio;
 228                dev->power.memalloc_noio = enable;
 229                spin_unlock_irq(&dev->power.lock);
 230
 231                /*
 232                 * not need to enable ancestors any more if the device
 233                 * has been enabled.
 234                 */
 235                if (enabled && enable)
 236                        break;
 237
 238                dev = dev->parent;
 239
 240                /*
 241                 * clear flag of the parent device only if all the
 242                 * children don't set the flag because ancestor's
 243                 * flag was set by any one of the descendants.
 244                 */
 245                if (!dev || (!enable &&
 246                             device_for_each_child(dev, NULL,
 247                                                   dev_memalloc_noio)))
 248                        break;
 249        }
 250        mutex_unlock(&dev_hotplug_mutex);
 251}
 252EXPORT_SYMBOL_GPL(pm_runtime_set_memalloc_noio);
 253
 254/**
 255 * rpm_check_suspend_allowed - Test whether a device may be suspended.
 256 * @dev: Device to test.
 257 */
 258static int rpm_check_suspend_allowed(struct device *dev)
 259{
 260        int retval = 0;
 261
 262        if (dev->power.runtime_error)
 263                retval = -EINVAL;
 264        else if (dev->power.disable_depth > 0)
 265                retval = -EACCES;
 266        else if (atomic_read(&dev->power.usage_count) > 0)
 267                retval = -EAGAIN;
 268        else if (!dev->power.ignore_children &&
 269                        atomic_read(&dev->power.child_count))
 270                retval = -EBUSY;
 271
 272        /* Pending resume requests take precedence over suspends. */
 273        else if ((dev->power.deferred_resume
 274                        && dev->power.runtime_status == RPM_SUSPENDING)
 275            || (dev->power.request_pending
 276                        && dev->power.request == RPM_REQ_RESUME))
 277                retval = -EAGAIN;
 278        else if (__dev_pm_qos_resume_latency(dev) == 0)
 279                retval = -EPERM;
 280        else if (dev->power.runtime_status == RPM_SUSPENDED)
 281                retval = 1;
 282
 283        return retval;
 284}
 285
 286static int rpm_get_suppliers(struct device *dev)
 287{
 288        struct device_link *link;
 289
 290        list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
 291                                device_links_read_lock_held()) {
 292                int retval;
 293
 294                if (!(link->flags & DL_FLAG_PM_RUNTIME) ||
 295                    READ_ONCE(link->status) == DL_STATE_SUPPLIER_UNBIND)
 296                        continue;
 297
 298                retval = pm_runtime_get_sync(link->supplier);
 299                /* Ignore suppliers with disabled runtime PM. */
 300                if (retval < 0 && retval != -EACCES) {
 301                        pm_runtime_put_noidle(link->supplier);
 302                        return retval;
 303                }
 304                refcount_inc(&link->rpm_active);
 305        }
 306        return 0;
 307}
 308
 309static void rpm_put_suppliers(struct device *dev)
 310{
 311        struct device_link *link;
 312
 313        list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
 314                                device_links_read_lock_held()) {
 315                if (READ_ONCE(link->status) == DL_STATE_SUPPLIER_UNBIND)
 316                        continue;
 317
 318                while (refcount_dec_not_one(&link->rpm_active))
 319                        pm_runtime_put(link->supplier);
 320        }
 321}
 322
 323/**
 324 * __rpm_callback - Run a given runtime PM callback for a given device.
 325 * @cb: Runtime PM callback to run.
 326 * @dev: Device to run the callback for.
 327 */
 328static int __rpm_callback(int (*cb)(struct device *), struct device *dev)
 329        __releases(&dev->power.lock) __acquires(&dev->power.lock)
 330{
 331        int retval, idx;
 332        bool use_links = dev->power.links_count > 0;
 333
 334        if (dev->power.irq_safe) {
 335                spin_unlock(&dev->power.lock);
 336        } else {
 337                spin_unlock_irq(&dev->power.lock);
 338
 339                /*
 340                 * Resume suppliers if necessary.
 341                 *
 342                 * The device's runtime PM status cannot change until this
 343                 * routine returns, so it is safe to read the status outside of
 344                 * the lock.
 345                 */
 346                if (use_links && dev->power.runtime_status == RPM_RESUMING) {
 347                        idx = device_links_read_lock();
 348
 349                        retval = rpm_get_suppliers(dev);
 350                        if (retval)
 351                                goto fail;
 352
 353                        device_links_read_unlock(idx);
 354                }
 355        }
 356
 357        retval = cb(dev);
 358
 359        if (dev->power.irq_safe) {
 360                spin_lock(&dev->power.lock);
 361        } else {
 362                /*
 363                 * If the device is suspending and the callback has returned
 364                 * success, drop the usage counters of the suppliers that have
 365                 * been reference counted on its resume.
 366                 *
 367                 * Do that if resume fails too.
 368                 */
 369                if (use_links
 370                    && ((dev->power.runtime_status == RPM_SUSPENDING && !retval)
 371                    || (dev->power.runtime_status == RPM_RESUMING && retval))) {
 372                        idx = device_links_read_lock();
 373
 374 fail:
 375                        rpm_put_suppliers(dev);
 376
 377                        device_links_read_unlock(idx);
 378                }
 379
 380                spin_lock_irq(&dev->power.lock);
 381        }
 382
 383        return retval;
 384}
 385
 386/**
 387 * rpm_idle - Notify device bus type if the device can be suspended.
 388 * @dev: Device to notify the bus type about.
 389 * @rpmflags: Flag bits.
 390 *
 391 * Check if the device's runtime PM status allows it to be suspended.  If
 392 * another idle notification has been started earlier, return immediately.  If
 393 * the RPM_ASYNC flag is set then queue an idle-notification request; otherwise
 394 * run the ->runtime_idle() callback directly. If the ->runtime_idle callback
 395 * doesn't exist or if it returns 0, call rpm_suspend with the RPM_AUTO flag.
 396 *
 397 * This function must be called under dev->power.lock with interrupts disabled.
 398 */
 399static int rpm_idle(struct device *dev, int rpmflags)
 400{
 401        int (*callback)(struct device *);
 402        int retval;
 403
 404        trace_rpm_idle_rcuidle(dev, rpmflags);
 405        retval = rpm_check_suspend_allowed(dev);
 406        if (retval < 0)
 407                ;       /* Conditions are wrong. */
 408
 409        /* Idle notifications are allowed only in the RPM_ACTIVE state. */
 410        else if (dev->power.runtime_status != RPM_ACTIVE)
 411                retval = -EAGAIN;
 412
 413        /*
 414         * Any pending request other than an idle notification takes
 415         * precedence over us, except that the timer may be running.
 416         */
 417        else if (dev->power.request_pending &&
 418            dev->power.request > RPM_REQ_IDLE)
 419                retval = -EAGAIN;
 420
 421        /* Act as though RPM_NOWAIT is always set. */
 422        else if (dev->power.idle_notification)
 423                retval = -EINPROGRESS;
 424        if (retval)
 425                goto out;
 426
 427        /* Pending requests need to be canceled. */
 428        dev->power.request = RPM_REQ_NONE;
 429
 430        if (dev->power.no_callbacks)
 431                goto out;
 432
 433        /* Carry out an asynchronous or a synchronous idle notification. */
 434        if (rpmflags & RPM_ASYNC) {
 435                dev->power.request = RPM_REQ_IDLE;
 436                if (!dev->power.request_pending) {
 437                        dev->power.request_pending = true;
 438                        queue_work(pm_wq, &dev->power.work);
 439                }
 440                trace_rpm_return_int_rcuidle(dev, _THIS_IP_, 0);
 441                return 0;
 442        }
 443
 444        dev->power.idle_notification = true;
 445
 446        callback = RPM_GET_CALLBACK(dev, runtime_idle);
 447
 448        if (callback)
 449                retval = __rpm_callback(callback, dev);
 450
 451        dev->power.idle_notification = false;
 452        wake_up_all(&dev->power.wait_queue);
 453
 454 out:
 455        trace_rpm_return_int_rcuidle(dev, _THIS_IP_, retval);
 456        return retval ? retval : rpm_suspend(dev, rpmflags | RPM_AUTO);
 457}
 458
 459/**
 460 * rpm_callback - Run a given runtime PM callback for a given device.
 461 * @cb: Runtime PM callback to run.
 462 * @dev: Device to run the callback for.
 463 */
 464static int rpm_callback(int (*cb)(struct device *), struct device *dev)
 465{
 466        int retval;
 467
 468        if (!cb)
 469                return -ENOSYS;
 470
 471        if (dev->power.memalloc_noio) {
 472                unsigned int noio_flag;
 473
 474                /*
 475                 * Deadlock might be caused if memory allocation with
 476                 * GFP_KERNEL happens inside runtime_suspend and
 477                 * runtime_resume callbacks of one block device's
 478                 * ancestor or the block device itself. Network
 479                 * device might be thought as part of iSCSI block
 480                 * device, so network device and its ancestor should
 481                 * be marked as memalloc_noio too.
 482                 */
 483                noio_flag = memalloc_noio_save();
 484                retval = __rpm_callback(cb, dev);
 485                memalloc_noio_restore(noio_flag);
 486        } else {
 487                retval = __rpm_callback(cb, dev);
 488        }
 489
 490        dev->power.runtime_error = retval;
 491        return retval != -EACCES ? retval : -EIO;
 492}
 493
 494/**
 495 * rpm_suspend - Carry out runtime suspend of given device.
 496 * @dev: Device to suspend.
 497 * @rpmflags: Flag bits.
 498 *
 499 * Check if the device's runtime PM status allows it to be suspended.
 500 * Cancel a pending idle notification, autosuspend or suspend. If
 501 * another suspend has been started earlier, either return immediately
 502 * or wait for it to finish, depending on the RPM_NOWAIT and RPM_ASYNC
 503 * flags. If the RPM_ASYNC flag is set then queue a suspend request;
 504 * otherwise run the ->runtime_suspend() callback directly. When
 505 * ->runtime_suspend succeeded, if a deferred resume was requested while
 506 * the callback was running then carry it out, otherwise send an idle
 507 * notification for its parent (if the suspend succeeded and both
 508 * ignore_children of parent->power and irq_safe of dev->power are not set).
 509 * If ->runtime_suspend failed with -EAGAIN or -EBUSY, and if the RPM_AUTO
 510 * flag is set and the next autosuspend-delay expiration time is in the
 511 * future, schedule another autosuspend attempt.
 512 *
 513 * This function must be called under dev->power.lock with interrupts disabled.
 514 */
 515static int rpm_suspend(struct device *dev, int rpmflags)
 516        __releases(&dev->power.lock) __acquires(&dev->power.lock)
 517{
 518        int (*callback)(struct device *);
 519        struct device *parent = NULL;
 520        int retval;
 521
 522        trace_rpm_suspend_rcuidle(dev, rpmflags);
 523
 524 repeat:
 525        retval = rpm_check_suspend_allowed(dev);
 526
 527        if (retval < 0)
 528                ;       /* Conditions are wrong. */
 529
 530        /* Synchronous suspends are not allowed in the RPM_RESUMING state. */
 531        else if (dev->power.runtime_status == RPM_RESUMING &&
 532            !(rpmflags & RPM_ASYNC))
 533                retval = -EAGAIN;
 534        if (retval)
 535                goto out;
 536
 537        /* If the autosuspend_delay time hasn't expired yet, reschedule. */
 538        if ((rpmflags & RPM_AUTO)
 539            && dev->power.runtime_status != RPM_SUSPENDING) {
 540                u64 expires = pm_runtime_autosuspend_expiration(dev);
 541
 542                if (expires != 0) {
 543                        /* Pending requests need to be canceled. */
 544                        dev->power.request = RPM_REQ_NONE;
 545
 546                        /*
 547                         * Optimization: If the timer is already running and is
 548                         * set to expire at or before the autosuspend delay,
 549                         * avoid the overhead of resetting it.  Just let it
 550                         * expire; pm_suspend_timer_fn() will take care of the
 551                         * rest.
 552                         */
 553                        if (!(dev->power.timer_expires &&
 554                                        dev->power.timer_expires <= expires)) {
 555                                /*
 556                                 * We add a slack of 25% to gather wakeups
 557                                 * without sacrificing the granularity.
 558                                 */
 559                                u64 slack = (u64)READ_ONCE(dev->power.autosuspend_delay) *
 560                                                    (NSEC_PER_MSEC >> 2);
 561
 562                                dev->power.timer_expires = expires;
 563                                hrtimer_start_range_ns(&dev->power.suspend_timer,
 564                                                ns_to_ktime(expires),
 565                                                slack,
 566                                                HRTIMER_MODE_ABS);
 567                        }
 568                        dev->power.timer_autosuspends = 1;
 569                        goto out;
 570                }
 571        }
 572
 573        /* Other scheduled or pending requests need to be canceled. */
 574        pm_runtime_cancel_pending(dev);
 575
 576        if (dev->power.runtime_status == RPM_SUSPENDING) {
 577                DEFINE_WAIT(wait);
 578
 579                if (rpmflags & (RPM_ASYNC | RPM_NOWAIT)) {
 580                        retval = -EINPROGRESS;
 581                        goto out;
 582                }
 583
 584                if (dev->power.irq_safe) {
 585                        spin_unlock(&dev->power.lock);
 586
 587                        cpu_relax();
 588
 589                        spin_lock(&dev->power.lock);
 590                        goto repeat;
 591                }
 592
 593                /* Wait for the other suspend running in parallel with us. */
 594                for (;;) {
 595                        prepare_to_wait(&dev->power.wait_queue, &wait,
 596                                        TASK_UNINTERRUPTIBLE);
 597                        if (dev->power.runtime_status != RPM_SUSPENDING)
 598                                break;
 599
 600                        spin_unlock_irq(&dev->power.lock);
 601
 602                        schedule();
 603
 604                        spin_lock_irq(&dev->power.lock);
 605                }
 606                finish_wait(&dev->power.wait_queue, &wait);
 607                goto repeat;
 608        }
 609
 610        if (dev->power.no_callbacks)
 611                goto no_callback;       /* Assume success. */
 612
 613        /* Carry out an asynchronous or a synchronous suspend. */
 614        if (rpmflags & RPM_ASYNC) {
 615                dev->power.request = (rpmflags & RPM_AUTO) ?
 616                    RPM_REQ_AUTOSUSPEND : RPM_REQ_SUSPEND;
 617                if (!dev->power.request_pending) {
 618                        dev->power.request_pending = true;
 619                        queue_work(pm_wq, &dev->power.work);
 620                }
 621                goto out;
 622        }
 623
 624        __update_runtime_status(dev, RPM_SUSPENDING);
 625
 626        callback = RPM_GET_CALLBACK(dev, runtime_suspend);
 627
 628        dev_pm_enable_wake_irq_check(dev, true);
 629        retval = rpm_callback(callback, dev);
 630        if (retval)
 631                goto fail;
 632
 633 no_callback:
 634        __update_runtime_status(dev, RPM_SUSPENDED);
 635        pm_runtime_deactivate_timer(dev);
 636
 637        if (dev->parent) {
 638                parent = dev->parent;
 639                atomic_add_unless(&parent->power.child_count, -1, 0);
 640        }
 641        wake_up_all(&dev->power.wait_queue);
 642
 643        if (dev->power.deferred_resume) {
 644                dev->power.deferred_resume = false;
 645                rpm_resume(dev, 0);
 646                retval = -EAGAIN;
 647                goto out;
 648        }
 649
 650        /* Maybe the parent is now able to suspend. */
 651        if (parent && !parent->power.ignore_children && !dev->power.irq_safe) {
 652                spin_unlock(&dev->power.lock);
 653
 654                spin_lock(&parent->power.lock);
 655                rpm_idle(parent, RPM_ASYNC);
 656                spin_unlock(&parent->power.lock);
 657
 658                spin_lock(&dev->power.lock);
 659        }
 660
 661 out:
 662        trace_rpm_return_int_rcuidle(dev, _THIS_IP_, retval);
 663
 664        return retval;
 665
 666 fail:
 667        dev_pm_disable_wake_irq_check(dev);
 668        __update_runtime_status(dev, RPM_ACTIVE);
 669        dev->power.deferred_resume = false;
 670        wake_up_all(&dev->power.wait_queue);
 671
 672        if (retval == -EAGAIN || retval == -EBUSY) {
 673                dev->power.runtime_error = 0;
 674
 675                /*
 676                 * If the callback routine failed an autosuspend, and
 677                 * if the last_busy time has been updated so that there
 678                 * is a new autosuspend expiration time, automatically
 679                 * reschedule another autosuspend.
 680                 */
 681                if ((rpmflags & RPM_AUTO) &&
 682                    pm_runtime_autosuspend_expiration(dev) != 0)
 683                        goto repeat;
 684        } else {
 685                pm_runtime_cancel_pending(dev);
 686        }
 687        goto out;
 688}
 689
 690/**
 691 * rpm_resume - Carry out runtime resume of given device.
 692 * @dev: Device to resume.
 693 * @rpmflags: Flag bits.
 694 *
 695 * Check if the device's runtime PM status allows it to be resumed.  Cancel
 696 * any scheduled or pending requests.  If another resume has been started
 697 * earlier, either return immediately or wait for it to finish, depending on the
 698 * RPM_NOWAIT and RPM_ASYNC flags.  Similarly, if there's a suspend running in
 699 * parallel with this function, either tell the other process to resume after
 700 * suspending (deferred_resume) or wait for it to finish.  If the RPM_ASYNC
 701 * flag is set then queue a resume request; otherwise run the
 702 * ->runtime_resume() callback directly.  Queue an idle notification for the
 703 * device if the resume succeeded.
 704 *
 705 * This function must be called under dev->power.lock with interrupts disabled.
 706 */
 707static int rpm_resume(struct device *dev, int rpmflags)
 708        __releases(&dev->power.lock) __acquires(&dev->power.lock)
 709{
 710        int (*callback)(struct device *);
 711        struct device *parent = NULL;
 712        int retval = 0;
 713
 714        trace_rpm_resume_rcuidle(dev, rpmflags);
 715
 716 repeat:
 717        if (dev->power.runtime_error)
 718                retval = -EINVAL;
 719        else if (dev->power.disable_depth == 1 && dev->power.is_suspended
 720            && dev->power.runtime_status == RPM_ACTIVE)
 721                retval = 1;
 722        else if (dev->power.disable_depth > 0)
 723                retval = -EACCES;
 724        if (retval)
 725                goto out;
 726
 727        /*
 728         * Other scheduled or pending requests need to be canceled.  Small
 729         * optimization: If an autosuspend timer is running, leave it running
 730         * rather than cancelling it now only to restart it again in the near
 731         * future.
 732         */
 733        dev->power.request = RPM_REQ_NONE;
 734        if (!dev->power.timer_autosuspends)
 735                pm_runtime_deactivate_timer(dev);
 736
 737        if (dev->power.runtime_status == RPM_ACTIVE) {
 738                retval = 1;
 739                goto out;
 740        }
 741
 742        if (dev->power.runtime_status == RPM_RESUMING
 743            || dev->power.runtime_status == RPM_SUSPENDING) {
 744                DEFINE_WAIT(wait);
 745
 746                if (rpmflags & (RPM_ASYNC | RPM_NOWAIT)) {
 747                        if (dev->power.runtime_status == RPM_SUSPENDING)
 748                                dev->power.deferred_resume = true;
 749                        else
 750                                retval = -EINPROGRESS;
 751                        goto out;
 752                }
 753
 754                if (dev->power.irq_safe) {
 755                        spin_unlock(&dev->power.lock);
 756
 757                        cpu_relax();
 758
 759                        spin_lock(&dev->power.lock);
 760                        goto repeat;
 761                }
 762
 763                /* Wait for the operation carried out in parallel with us. */
 764                for (;;) {
 765                        prepare_to_wait(&dev->power.wait_queue, &wait,
 766                                        TASK_UNINTERRUPTIBLE);
 767                        if (dev->power.runtime_status != RPM_RESUMING
 768                            && dev->power.runtime_status != RPM_SUSPENDING)
 769                                break;
 770
 771                        spin_unlock_irq(&dev->power.lock);
 772
 773                        schedule();
 774
 775                        spin_lock_irq(&dev->power.lock);
 776                }
 777                finish_wait(&dev->power.wait_queue, &wait);
 778                goto repeat;
 779        }
 780
 781        /*
 782         * See if we can skip waking up the parent.  This is safe only if
 783         * power.no_callbacks is set, because otherwise we don't know whether
 784         * the resume will actually succeed.
 785         */
 786        if (dev->power.no_callbacks && !parent && dev->parent) {
 787                spin_lock_nested(&dev->parent->power.lock, SINGLE_DEPTH_NESTING);
 788                if (dev->parent->power.disable_depth > 0
 789                    || dev->parent->power.ignore_children
 790                    || dev->parent->power.runtime_status == RPM_ACTIVE) {
 791                        atomic_inc(&dev->parent->power.child_count);
 792                        spin_unlock(&dev->parent->power.lock);
 793                        retval = 1;
 794                        goto no_callback;       /* Assume success. */
 795                }
 796                spin_unlock(&dev->parent->power.lock);
 797        }
 798
 799        /* Carry out an asynchronous or a synchronous resume. */
 800        if (rpmflags & RPM_ASYNC) {
 801                dev->power.request = RPM_REQ_RESUME;
 802                if (!dev->power.request_pending) {
 803                        dev->power.request_pending = true;
 804                        queue_work(pm_wq, &dev->power.work);
 805                }
 806                retval = 0;
 807                goto out;
 808        }
 809
 810        if (!parent && dev->parent) {
 811                /*
 812                 * Increment the parent's usage counter and resume it if
 813                 * necessary.  Not needed if dev is irq-safe; then the
 814                 * parent is permanently resumed.
 815                 */
 816                parent = dev->parent;
 817                if (dev->power.irq_safe)
 818                        goto skip_parent;
 819                spin_unlock(&dev->power.lock);
 820
 821                pm_runtime_get_noresume(parent);
 822
 823                spin_lock(&parent->power.lock);
 824                /*
 825                 * Resume the parent if it has runtime PM enabled and not been
 826                 * set to ignore its children.
 827                 */
 828                if (!parent->power.disable_depth
 829                    && !parent->power.ignore_children) {
 830                        rpm_resume(parent, 0);
 831                        if (parent->power.runtime_status != RPM_ACTIVE)
 832                                retval = -EBUSY;
 833                }
 834                spin_unlock(&parent->power.lock);
 835
 836                spin_lock(&dev->power.lock);
 837                if (retval)
 838                        goto out;
 839                goto repeat;
 840        }
 841 skip_parent:
 842
 843        if (dev->power.no_callbacks)
 844                goto no_callback;       /* Assume success. */
 845
 846        __update_runtime_status(dev, RPM_RESUMING);
 847
 848        callback = RPM_GET_CALLBACK(dev, runtime_resume);
 849
 850        dev_pm_disable_wake_irq_check(dev);
 851        retval = rpm_callback(callback, dev);
 852        if (retval) {
 853                __update_runtime_status(dev, RPM_SUSPENDED);
 854                pm_runtime_cancel_pending(dev);
 855                dev_pm_enable_wake_irq_check(dev, false);
 856        } else {
 857 no_callback:
 858                __update_runtime_status(dev, RPM_ACTIVE);
 859                pm_runtime_mark_last_busy(dev);
 860                if (parent)
 861                        atomic_inc(&parent->power.child_count);
 862        }
 863        wake_up_all(&dev->power.wait_queue);
 864
 865        if (retval >= 0)
 866                rpm_idle(dev, RPM_ASYNC);
 867
 868 out:
 869        if (parent && !dev->power.irq_safe) {
 870                spin_unlock_irq(&dev->power.lock);
 871
 872                pm_runtime_put(parent);
 873
 874                spin_lock_irq(&dev->power.lock);
 875        }
 876
 877        trace_rpm_return_int_rcuidle(dev, _THIS_IP_, retval);
 878
 879        return retval;
 880}
 881
 882/**
 883 * pm_runtime_work - Universal runtime PM work function.
 884 * @work: Work structure used for scheduling the execution of this function.
 885 *
 886 * Use @work to get the device object the work is to be done for, determine what
 887 * is to be done and execute the appropriate runtime PM function.
 888 */
 889static void pm_runtime_work(struct work_struct *work)
 890{
 891        struct device *dev = container_of(work, struct device, power.work);
 892        enum rpm_request req;
 893
 894        spin_lock_irq(&dev->power.lock);
 895
 896        if (!dev->power.request_pending)
 897                goto out;
 898
 899        req = dev->power.request;
 900        dev->power.request = RPM_REQ_NONE;
 901        dev->power.request_pending = false;
 902
 903        switch (req) {
 904        case RPM_REQ_NONE:
 905                break;
 906        case RPM_REQ_IDLE:
 907                rpm_idle(dev, RPM_NOWAIT);
 908                break;
 909        case RPM_REQ_SUSPEND:
 910                rpm_suspend(dev, RPM_NOWAIT);
 911                break;
 912        case RPM_REQ_AUTOSUSPEND:
 913                rpm_suspend(dev, RPM_NOWAIT | RPM_AUTO);
 914                break;
 915        case RPM_REQ_RESUME:
 916                rpm_resume(dev, RPM_NOWAIT);
 917                break;
 918        }
 919
 920 out:
 921        spin_unlock_irq(&dev->power.lock);
 922}
 923
 924/**
 925 * pm_suspend_timer_fn - Timer function for pm_schedule_suspend().
 926 * @data: Device pointer passed by pm_schedule_suspend().
 927 *
 928 * Check if the time is right and queue a suspend request.
 929 */
 930static enum hrtimer_restart  pm_suspend_timer_fn(struct hrtimer *timer)
 931{
 932        struct device *dev = container_of(timer, struct device, power.suspend_timer);
 933        unsigned long flags;
 934        u64 expires;
 935
 936        spin_lock_irqsave(&dev->power.lock, flags);
 937
 938        expires = dev->power.timer_expires;
 939        /*
 940         * If 'expires' is after the current time, we've been called
 941         * too early.
 942         */
 943        if (expires > 0 && expires < ktime_get_mono_fast_ns()) {
 944                dev->power.timer_expires = 0;
 945                rpm_suspend(dev, dev->power.timer_autosuspends ?
 946                    (RPM_ASYNC | RPM_AUTO) : RPM_ASYNC);
 947        }
 948
 949        spin_unlock_irqrestore(&dev->power.lock, flags);
 950
 951        return HRTIMER_NORESTART;
 952}
 953
 954/**
 955 * pm_schedule_suspend - Set up a timer to submit a suspend request in future.
 956 * @dev: Device to suspend.
 957 * @delay: Time to wait before submitting a suspend request, in milliseconds.
 958 */
 959int pm_schedule_suspend(struct device *dev, unsigned int delay)
 960{
 961        unsigned long flags;
 962        u64 expires;
 963        int retval;
 964
 965        spin_lock_irqsave(&dev->power.lock, flags);
 966
 967        if (!delay) {
 968                retval = rpm_suspend(dev, RPM_ASYNC);
 969                goto out;
 970        }
 971
 972        retval = rpm_check_suspend_allowed(dev);
 973        if (retval)
 974                goto out;
 975
 976        /* Other scheduled or pending requests need to be canceled. */
 977        pm_runtime_cancel_pending(dev);
 978
 979        expires = ktime_get_mono_fast_ns() + (u64)delay * NSEC_PER_MSEC;
 980        dev->power.timer_expires = expires;
 981        dev->power.timer_autosuspends = 0;
 982        hrtimer_start(&dev->power.suspend_timer, expires, HRTIMER_MODE_ABS);
 983
 984 out:
 985        spin_unlock_irqrestore(&dev->power.lock, flags);
 986
 987        return retval;
 988}
 989EXPORT_SYMBOL_GPL(pm_schedule_suspend);
 990
 991/**
 992 * __pm_runtime_idle - Entry point for runtime idle operations.
 993 * @dev: Device to send idle notification for.
 994 * @rpmflags: Flag bits.
 995 *
 996 * If the RPM_GET_PUT flag is set, decrement the device's usage count and
 997 * return immediately if it is larger than zero.  Then carry out an idle
 998 * notification, either synchronous or asynchronous.
 999 *
1000 * This routine may be called in atomic context if the RPM_ASYNC flag is set,
1001 * or if pm_runtime_irq_safe() has been called.
1002 */
1003int __pm_runtime_idle(struct device *dev, int rpmflags)
1004{
1005        unsigned long flags;
1006        int retval;
1007
1008        if (rpmflags & RPM_GET_PUT) {
1009                if (!atomic_dec_and_test(&dev->power.usage_count))
1010                        return 0;
1011        }
1012
1013        might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);
1014
1015        spin_lock_irqsave(&dev->power.lock, flags);
1016        retval = rpm_idle(dev, rpmflags);
1017        spin_unlock_irqrestore(&dev->power.lock, flags);
1018
1019        return retval;
1020}
1021EXPORT_SYMBOL_GPL(__pm_runtime_idle);
1022
1023/**
1024 * __pm_runtime_suspend - Entry point for runtime put/suspend operations.
1025 * @dev: Device to suspend.
1026 * @rpmflags: Flag bits.
1027 *
1028 * If the RPM_GET_PUT flag is set, decrement the device's usage count and
1029 * return immediately if it is larger than zero.  Then carry out a suspend,
1030 * either synchronous or asynchronous.
1031 *
1032 * This routine may be called in atomic context if the RPM_ASYNC flag is set,
1033 * or if pm_runtime_irq_safe() has been called.
1034 */
1035int __pm_runtime_suspend(struct device *dev, int rpmflags)
1036{
1037        unsigned long flags;
1038        int retval;
1039
1040        if (rpmflags & RPM_GET_PUT) {
1041                if (!atomic_dec_and_test(&dev->power.usage_count))
1042                        return 0;
1043        }
1044
1045        might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);
1046
1047        spin_lock_irqsave(&dev->power.lock, flags);
1048        retval = rpm_suspend(dev, rpmflags);
1049        spin_unlock_irqrestore(&dev->power.lock, flags);
1050
1051        return retval;
1052}
1053EXPORT_SYMBOL_GPL(__pm_runtime_suspend);
1054
1055/**
1056 * __pm_runtime_resume - Entry point for runtime resume operations.
1057 * @dev: Device to resume.
1058 * @rpmflags: Flag bits.
1059 *
1060 * If the RPM_GET_PUT flag is set, increment the device's usage count.  Then
1061 * carry out a resume, either synchronous or asynchronous.
1062 *
1063 * This routine may be called in atomic context if the RPM_ASYNC flag is set,
1064 * or if pm_runtime_irq_safe() has been called.
1065 */
1066int __pm_runtime_resume(struct device *dev, int rpmflags)
1067{
1068        unsigned long flags;
1069        int retval;
1070
1071        might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe &&
1072                        dev->power.runtime_status != RPM_ACTIVE);
1073
1074        if (rpmflags & RPM_GET_PUT)
1075                atomic_inc(&dev->power.usage_count);
1076
1077        spin_lock_irqsave(&dev->power.lock, flags);
1078        retval = rpm_resume(dev, rpmflags);
1079        spin_unlock_irqrestore(&dev->power.lock, flags);
1080
1081        return retval;
1082}
1083EXPORT_SYMBOL_GPL(__pm_runtime_resume);
1084
1085/**
1086 * pm_runtime_get_if_in_use - Conditionally bump up the device's usage counter.
1087 * @dev: Device to handle.
1088 *
1089 * Return -EINVAL if runtime PM is disabled for the device.
1090 *
1091 * If that's not the case and if the device's runtime PM status is RPM_ACTIVE
1092 * and the runtime PM usage counter is nonzero, increment the counter and
1093 * return 1.  Otherwise return 0 without changing the counter.
1094 */
1095int pm_runtime_get_if_in_use(struct device *dev)
1096{
1097        unsigned long flags;
1098        int retval;
1099
1100        spin_lock_irqsave(&dev->power.lock, flags);
1101        retval = dev->power.disable_depth > 0 ? -EINVAL :
1102                dev->power.runtime_status == RPM_ACTIVE
1103                        && atomic_inc_not_zero(&dev->power.usage_count);
1104        spin_unlock_irqrestore(&dev->power.lock, flags);
1105        return retval;
1106}
1107EXPORT_SYMBOL_GPL(pm_runtime_get_if_in_use);
1108
1109/**
1110 * __pm_runtime_set_status - Set runtime PM status of a device.
1111 * @dev: Device to handle.
1112 * @status: New runtime PM status of the device.
1113 *
1114 * If runtime PM of the device is disabled or its power.runtime_error field is
1115 * different from zero, the status may be changed either to RPM_ACTIVE, or to
1116 * RPM_SUSPENDED, as long as that reflects the actual state of the device.
1117 * However, if the device has a parent and the parent is not active, and the
1118 * parent's power.ignore_children flag is unset, the device's status cannot be
1119 * set to RPM_ACTIVE, so -EBUSY is returned in that case.
1120 *
1121 * If successful, __pm_runtime_set_status() clears the power.runtime_error field
1122 * and the device parent's counter of unsuspended children is modified to
1123 * reflect the new status.  If the new status is RPM_SUSPENDED, an idle
1124 * notification request for the parent is submitted.
1125 *
1126 * If @dev has any suppliers (as reflected by device links to them), and @status
1127 * is RPM_ACTIVE, they will be activated upfront and if the activation of one
1128 * of them fails, the status of @dev will be changed to RPM_SUSPENDED (instead
1129 * of the @status value) and the suppliers will be deacticated on exit.  The
1130 * error returned by the failing supplier activation will be returned in that
1131 * case.
1132 */
1133int __pm_runtime_set_status(struct device *dev, unsigned int status)
1134{
1135        struct device *parent = dev->parent;
1136        bool notify_parent = false;
1137        int error = 0;
1138
1139        if (status != RPM_ACTIVE && status != RPM_SUSPENDED)
1140                return -EINVAL;
1141
1142        spin_lock_irq(&dev->power.lock);
1143
1144        /*
1145         * Prevent PM-runtime from being enabled for the device or return an
1146         * error if it is enabled already and working.
1147         */
1148        if (dev->power.runtime_error || dev->power.disable_depth)
1149                dev->power.disable_depth++;
1150        else
1151                error = -EAGAIN;
1152
1153        spin_unlock_irq(&dev->power.lock);
1154
1155        if (error)
1156                return error;
1157
1158        /*
1159         * If the new status is RPM_ACTIVE, the suppliers can be activated
1160         * upfront regardless of the current status, because next time
1161         * rpm_put_suppliers() runs, the rpm_active refcounts of the links
1162         * involved will be dropped down to one anyway.
1163         */
1164        if (status == RPM_ACTIVE) {
1165                int idx = device_links_read_lock();
1166
1167                error = rpm_get_suppliers(dev);
1168                if (error)
1169                        status = RPM_SUSPENDED;
1170
1171                device_links_read_unlock(idx);
1172        }
1173
1174        spin_lock_irq(&dev->power.lock);
1175
1176        if (dev->power.runtime_status == status || !parent)
1177                goto out_set;
1178
1179        if (status == RPM_SUSPENDED) {
1180                atomic_add_unless(&parent->power.child_count, -1, 0);
1181                notify_parent = !parent->power.ignore_children;
1182        } else {
1183                spin_lock_nested(&parent->power.lock, SINGLE_DEPTH_NESTING);
1184
1185                /*
1186                 * It is invalid to put an active child under a parent that is
1187                 * not active, has runtime PM enabled and the
1188                 * 'power.ignore_children' flag unset.
1189                 */
1190                if (!parent->power.disable_depth
1191                    && !parent->power.ignore_children
1192                    && parent->power.runtime_status != RPM_ACTIVE) {
1193                        dev_err(dev, "runtime PM trying to activate child device %s but parent (%s) is not active\n",
1194                                dev_name(dev),
1195                                dev_name(parent));
1196                        error = -EBUSY;
1197                } else if (dev->power.runtime_status == RPM_SUSPENDED) {
1198                        atomic_inc(&parent->power.child_count);
1199                }
1200
1201                spin_unlock(&parent->power.lock);
1202
1203                if (error) {
1204                        status = RPM_SUSPENDED;
1205                        goto out;
1206                }
1207        }
1208
1209 out_set:
1210        __update_runtime_status(dev, status);
1211        if (!error)
1212                dev->power.runtime_error = 0;
1213
1214 out:
1215        spin_unlock_irq(&dev->power.lock);
1216
1217        if (notify_parent)
1218                pm_request_idle(parent);
1219
1220        if (status == RPM_SUSPENDED) {
1221                int idx = device_links_read_lock();
1222
1223                rpm_put_suppliers(dev);
1224
1225                device_links_read_unlock(idx);
1226        }
1227
1228        pm_runtime_enable(dev);
1229
1230        return error;
1231}
1232EXPORT_SYMBOL_GPL(__pm_runtime_set_status);
1233
1234/**
1235 * __pm_runtime_barrier - Cancel pending requests and wait for completions.
1236 * @dev: Device to handle.
1237 *
1238 * Flush all pending requests for the device from pm_wq and wait for all
1239 * runtime PM operations involving the device in progress to complete.
1240 *
1241 * Should be called under dev->power.lock with interrupts disabled.
1242 */
1243static void __pm_runtime_barrier(struct device *dev)
1244{
1245        pm_runtime_deactivate_timer(dev);
1246
1247        if (dev->power.request_pending) {
1248                dev->power.request = RPM_REQ_NONE;
1249                spin_unlock_irq(&dev->power.lock);
1250
1251                cancel_work_sync(&dev->power.work);
1252
1253                spin_lock_irq(&dev->power.lock);
1254                dev->power.request_pending = false;
1255        }
1256
1257        if (dev->power.runtime_status == RPM_SUSPENDING
1258            || dev->power.runtime_status == RPM_RESUMING
1259            || dev->power.idle_notification) {
1260                DEFINE_WAIT(wait);
1261
1262                /* Suspend, wake-up or idle notification in progress. */
1263                for (;;) {
1264                        prepare_to_wait(&dev->power.wait_queue, &wait,
1265                                        TASK_UNINTERRUPTIBLE);
1266                        if (dev->power.runtime_status != RPM_SUSPENDING
1267                            && dev->power.runtime_status != RPM_RESUMING
1268                            && !dev->power.idle_notification)
1269                                break;
1270                        spin_unlock_irq(&dev->power.lock);
1271
1272                        schedule();
1273
1274                        spin_lock_irq(&dev->power.lock);
1275                }
1276                finish_wait(&dev->power.wait_queue, &wait);
1277        }
1278}
1279
1280/**
1281 * pm_runtime_barrier - Flush pending requests and wait for completions.
1282 * @dev: Device to handle.
1283 *
1284 * Prevent the device from being suspended by incrementing its usage counter and
1285 * if there's a pending resume request for the device, wake the device up.
1286 * Next, make sure that all pending requests for the device have been flushed
1287 * from pm_wq and wait for all runtime PM operations involving the device in
1288 * progress to complete.
1289 *
1290 * Return value:
1291 * 1, if there was a resume request pending and the device had to be woken up,
1292 * 0, otherwise
1293 */
1294int pm_runtime_barrier(struct device *dev)
1295{
1296        int retval = 0;
1297
1298        pm_runtime_get_noresume(dev);
1299        spin_lock_irq(&dev->power.lock);
1300
1301        if (dev->power.request_pending
1302            && dev->power.request == RPM_REQ_RESUME) {
1303                rpm_resume(dev, 0);
1304                retval = 1;
1305        }
1306
1307        __pm_runtime_barrier(dev);
1308
1309        spin_unlock_irq(&dev->power.lock);
1310        pm_runtime_put_noidle(dev);
1311
1312        return retval;
1313}
1314EXPORT_SYMBOL_GPL(pm_runtime_barrier);
1315
1316/**
1317 * __pm_runtime_disable - Disable runtime PM of a device.
1318 * @dev: Device to handle.
1319 * @check_resume: If set, check if there's a resume request for the device.
1320 *
1321 * Increment power.disable_depth for the device and if it was zero previously,
1322 * cancel all pending runtime PM requests for the device and wait for all
1323 * operations in progress to complete.  The device can be either active or
1324 * suspended after its runtime PM has been disabled.
1325 *
1326 * If @check_resume is set and there's a resume request pending when
1327 * __pm_runtime_disable() is called and power.disable_depth is zero, the
1328 * function will wake up the device before disabling its runtime PM.
1329 */
1330void __pm_runtime_disable(struct device *dev, bool check_resume)
1331{
1332        spin_lock_irq(&dev->power.lock);
1333
1334        if (dev->power.disable_depth > 0) {
1335                dev->power.disable_depth++;
1336                goto out;
1337        }
1338
1339        /*
1340         * Wake up the device if there's a resume request pending, because that
1341         * means there probably is some I/O to process and disabling runtime PM
1342         * shouldn't prevent the device from processing the I/O.
1343         */
1344        if (check_resume && dev->power.request_pending
1345            && dev->power.request == RPM_REQ_RESUME) {
1346                /*
1347                 * Prevent suspends and idle notifications from being carried
1348                 * out after we have woken up the device.
1349                 */
1350                pm_runtime_get_noresume(dev);
1351
1352                rpm_resume(dev, 0);
1353
1354                pm_runtime_put_noidle(dev);
1355        }
1356
1357        /* Update time accounting before disabling PM-runtime. */
1358        update_pm_runtime_accounting(dev);
1359
1360        if (!dev->power.disable_depth++)
1361                __pm_runtime_barrier(dev);
1362
1363 out:
1364        spin_unlock_irq(&dev->power.lock);
1365}
1366EXPORT_SYMBOL_GPL(__pm_runtime_disable);
1367
1368/**
1369 * pm_runtime_enable - Enable runtime PM of a device.
1370 * @dev: Device to handle.
1371 */
1372void pm_runtime_enable(struct device *dev)
1373{
1374        unsigned long flags;
1375
1376        spin_lock_irqsave(&dev->power.lock, flags);
1377
1378        if (dev->power.disable_depth > 0) {
1379                dev->power.disable_depth--;
1380
1381                /* About to enable runtime pm, set accounting_timestamp to now */
1382                if (!dev->power.disable_depth)
1383                        dev->power.accounting_timestamp = ktime_get_mono_fast_ns();
1384        } else {
1385                dev_warn(dev, "Unbalanced %s!\n", __func__);
1386        }
1387
1388        WARN(!dev->power.disable_depth &&
1389             dev->power.runtime_status == RPM_SUSPENDED &&
1390             !dev->power.ignore_children &&
1391             atomic_read(&dev->power.child_count) > 0,
1392             "Enabling runtime PM for inactive device (%s) with active children\n",
1393             dev_name(dev));
1394
1395        spin_unlock_irqrestore(&dev->power.lock, flags);
1396}
1397EXPORT_SYMBOL_GPL(pm_runtime_enable);
1398
1399/**
1400 * pm_runtime_forbid - Block runtime PM of a device.
1401 * @dev: Device to handle.
1402 *
1403 * Increase the device's usage count and clear its power.runtime_auto flag,
1404 * so that it cannot be suspended at run time until pm_runtime_allow() is called
1405 * for it.
1406 */
1407void pm_runtime_forbid(struct device *dev)
1408{
1409        spin_lock_irq(&dev->power.lock);
1410        if (!dev->power.runtime_auto)
1411                goto out;
1412
1413        dev->power.runtime_auto = false;
1414        atomic_inc(&dev->power.usage_count);
1415        rpm_resume(dev, 0);
1416
1417 out:
1418        spin_unlock_irq(&dev->power.lock);
1419}
1420EXPORT_SYMBOL_GPL(pm_runtime_forbid);
1421
1422/**
1423 * pm_runtime_allow - Unblock runtime PM of a device.
1424 * @dev: Device to handle.
1425 *
1426 * Decrease the device's usage count and set its power.runtime_auto flag.
1427 */
1428void pm_runtime_allow(struct device *dev)
1429{
1430        spin_lock_irq(&dev->power.lock);
1431        if (dev->power.runtime_auto)
1432                goto out;
1433
1434        dev->power.runtime_auto = true;
1435        if (atomic_dec_and_test(&dev->power.usage_count))
1436                rpm_idle(dev, RPM_AUTO | RPM_ASYNC);
1437
1438 out:
1439        spin_unlock_irq(&dev->power.lock);
1440}
1441EXPORT_SYMBOL_GPL(pm_runtime_allow);
1442
1443/**
1444 * pm_runtime_no_callbacks - Ignore runtime PM callbacks for a device.
1445 * @dev: Device to handle.
1446 *
1447 * Set the power.no_callbacks flag, which tells the PM core that this
1448 * device is power-managed through its parent and has no runtime PM
1449 * callbacks of its own.  The runtime sysfs attributes will be removed.
1450 */
1451void pm_runtime_no_callbacks(struct device *dev)
1452{
1453        spin_lock_irq(&dev->power.lock);
1454        dev->power.no_callbacks = 1;
1455        spin_unlock_irq(&dev->power.lock);
1456        if (device_is_registered(dev))
1457                rpm_sysfs_remove(dev);
1458}
1459EXPORT_SYMBOL_GPL(pm_runtime_no_callbacks);
1460
1461/**
1462 * pm_runtime_irq_safe - Leave interrupts disabled during callbacks.
1463 * @dev: Device to handle
1464 *
1465 * Set the power.irq_safe flag, which tells the PM core that the
1466 * ->runtime_suspend() and ->runtime_resume() callbacks for this device should
1467 * always be invoked with the spinlock held and interrupts disabled.  It also
1468 * causes the parent's usage counter to be permanently incremented, preventing
1469 * the parent from runtime suspending -- otherwise an irq-safe child might have
1470 * to wait for a non-irq-safe parent.
1471 */
1472void pm_runtime_irq_safe(struct device *dev)
1473{
1474        if (dev->parent)
1475                pm_runtime_get_sync(dev->parent);
1476        spin_lock_irq(&dev->power.lock);
1477        dev->power.irq_safe = 1;
1478        spin_unlock_irq(&dev->power.lock);
1479}
1480EXPORT_SYMBOL_GPL(pm_runtime_irq_safe);
1481
1482/**
1483 * update_autosuspend - Handle a change to a device's autosuspend settings.
1484 * @dev: Device to handle.
1485 * @old_delay: The former autosuspend_delay value.
1486 * @old_use: The former use_autosuspend value.
1487 *
1488 * Prevent runtime suspend if the new delay is negative and use_autosuspend is
1489 * set; otherwise allow it.  Send an idle notification if suspends are allowed.
1490 *
1491 * This function must be called under dev->power.lock with interrupts disabled.
1492 */
1493static void update_autosuspend(struct device *dev, int old_delay, int old_use)
1494{
1495        int delay = dev->power.autosuspend_delay;
1496
1497        /* Should runtime suspend be prevented now? */
1498        if (dev->power.use_autosuspend && delay < 0) {
1499
1500                /* If it used to be allowed then prevent it. */
1501                if (!old_use || old_delay >= 0) {
1502                        atomic_inc(&dev->power.usage_count);
1503                        rpm_resume(dev, 0);
1504                }
1505        }
1506
1507        /* Runtime suspend should be allowed now. */
1508        else {
1509
1510                /* If it used to be prevented then allow it. */
1511                if (old_use && old_delay < 0)
1512                        atomic_dec(&dev->power.usage_count);
1513
1514                /* Maybe we can autosuspend now. */
1515                rpm_idle(dev, RPM_AUTO);
1516        }
1517}
1518
1519/**
1520 * pm_runtime_set_autosuspend_delay - Set a device's autosuspend_delay value.
1521 * @dev: Device to handle.
1522 * @delay: Value of the new delay in milliseconds.
1523 *
1524 * Set the device's power.autosuspend_delay value.  If it changes to negative
1525 * and the power.use_autosuspend flag is set, prevent runtime suspends.  If it
1526 * changes the other way, allow runtime suspends.
1527 */
1528void pm_runtime_set_autosuspend_delay(struct device *dev, int delay)
1529{
1530        int old_delay, old_use;
1531
1532        spin_lock_irq(&dev->power.lock);
1533        old_delay = dev->power.autosuspend_delay;
1534        old_use = dev->power.use_autosuspend;
1535        dev->power.autosuspend_delay = delay;
1536        update_autosuspend(dev, old_delay, old_use);
1537        spin_unlock_irq(&dev->power.lock);
1538}
1539EXPORT_SYMBOL_GPL(pm_runtime_set_autosuspend_delay);
1540
1541/**
1542 * __pm_runtime_use_autosuspend - Set a device's use_autosuspend flag.
1543 * @dev: Device to handle.
1544 * @use: New value for use_autosuspend.
1545 *
1546 * Set the device's power.use_autosuspend flag, and allow or prevent runtime
1547 * suspends as needed.
1548 */
1549void __pm_runtime_use_autosuspend(struct device *dev, bool use)
1550{
1551        int old_delay, old_use;
1552
1553        spin_lock_irq(&dev->power.lock);
1554        old_delay = dev->power.autosuspend_delay;
1555        old_use = dev->power.use_autosuspend;
1556        dev->power.use_autosuspend = use;
1557        update_autosuspend(dev, old_delay, old_use);
1558        spin_unlock_irq(&dev->power.lock);
1559}
1560EXPORT_SYMBOL_GPL(__pm_runtime_use_autosuspend);
1561
1562/**
1563 * pm_runtime_init - Initialize runtime PM fields in given device object.
1564 * @dev: Device object to initialize.
1565 */
1566void pm_runtime_init(struct device *dev)
1567{
1568        dev->power.runtime_status = RPM_SUSPENDED;
1569        dev->power.idle_notification = false;
1570
1571        dev->power.disable_depth = 1;
1572        atomic_set(&dev->power.usage_count, 0);
1573
1574        dev->power.runtime_error = 0;
1575
1576        atomic_set(&dev->power.child_count, 0);
1577        pm_suspend_ignore_children(dev, false);
1578        dev->power.runtime_auto = true;
1579
1580        dev->power.request_pending = false;
1581        dev->power.request = RPM_REQ_NONE;
1582        dev->power.deferred_resume = false;
1583        INIT_WORK(&dev->power.work, pm_runtime_work);
1584
1585        dev->power.timer_expires = 0;
1586        hrtimer_init(&dev->power.suspend_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
1587        dev->power.suspend_timer.function = pm_suspend_timer_fn;
1588
1589        init_waitqueue_head(&dev->power.wait_queue);
1590}
1591
1592/**
1593 * pm_runtime_reinit - Re-initialize runtime PM fields in given device object.
1594 * @dev: Device object to re-initialize.
1595 */
1596void pm_runtime_reinit(struct device *dev)
1597{
1598        if (!pm_runtime_enabled(dev)) {
1599                if (dev->power.runtime_status == RPM_ACTIVE)
1600                        pm_runtime_set_suspended(dev);
1601                if (dev->power.irq_safe) {
1602                        spin_lock_irq(&dev->power.lock);
1603                        dev->power.irq_safe = 0;
1604                        spin_unlock_irq(&dev->power.lock);
1605                        if (dev->parent)
1606                                pm_runtime_put(dev->parent);
1607                }
1608        }
1609}
1610
1611/**
1612 * pm_runtime_remove - Prepare for removing a device from device hierarchy.
1613 * @dev: Device object being removed from device hierarchy.
1614 */
1615void pm_runtime_remove(struct device *dev)
1616{
1617        __pm_runtime_disable(dev, false);
1618        pm_runtime_reinit(dev);
1619}
1620
1621/**
1622 * pm_runtime_clean_up_links - Prepare links to consumers for driver removal.
1623 * @dev: Device whose driver is going to be removed.
1624 *
1625 * Check links from this device to any consumers and if any of them have active
1626 * runtime PM references to the device, drop the usage counter of the device
1627 * (as many times as needed).
1628 *
1629 * Links with the DL_FLAG_MANAGED flag unset are ignored.
1630 *
1631 * Since the device is guaranteed to be runtime-active at the point this is
1632 * called, nothing else needs to be done here.
1633 *
1634 * Moreover, this is called after device_links_busy() has returned 'false', so
1635 * the status of each link is guaranteed to be DL_STATE_SUPPLIER_UNBIND and
1636 * therefore rpm_active can't be manipulated concurrently.
1637 */
1638void pm_runtime_clean_up_links(struct device *dev)
1639{
1640        struct device_link *link;
1641        int idx;
1642
1643        idx = device_links_read_lock();
1644
1645        list_for_each_entry_rcu(link, &dev->links.consumers, s_node,
1646                                device_links_read_lock_held()) {
1647                if (!(link->flags & DL_FLAG_MANAGED))
1648                        continue;
1649
1650                while (refcount_dec_not_one(&link->rpm_active))
1651                        pm_runtime_put_noidle(dev);
1652        }
1653
1654        device_links_read_unlock(idx);
1655}
1656
1657/**
1658 * pm_runtime_get_suppliers - Resume and reference-count supplier devices.
1659 * @dev: Consumer device.
1660 */
1661void pm_runtime_get_suppliers(struct device *dev)
1662{
1663        struct device_link *link;
1664        int idx;
1665
1666        idx = device_links_read_lock();
1667
1668        list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
1669                                device_links_read_lock_held())
1670                if (link->flags & DL_FLAG_PM_RUNTIME) {
1671                        link->supplier_preactivated = true;
1672                        refcount_inc(&link->rpm_active);
1673                        pm_runtime_get_sync(link->supplier);
1674                }
1675
1676        device_links_read_unlock(idx);
1677}
1678
1679/**
1680 * pm_runtime_put_suppliers - Drop references to supplier devices.
1681 * @dev: Consumer device.
1682 */
1683void pm_runtime_put_suppliers(struct device *dev)
1684{
1685        struct device_link *link;
1686        int idx;
1687
1688        idx = device_links_read_lock();
1689
1690        list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
1691                                device_links_read_lock_held())
1692                if (link->supplier_preactivated) {
1693                        link->supplier_preactivated = false;
1694                        if (refcount_dec_not_one(&link->rpm_active))
1695                                pm_runtime_put(link->supplier);
1696                }
1697
1698        device_links_read_unlock(idx);
1699}
1700
1701void pm_runtime_new_link(struct device *dev)
1702{
1703        spin_lock_irq(&dev->power.lock);
1704        dev->power.links_count++;
1705        spin_unlock_irq(&dev->power.lock);
1706}
1707
1708void pm_runtime_drop_link(struct device *dev)
1709{
1710        spin_lock_irq(&dev->power.lock);
1711        WARN_ON(dev->power.links_count == 0);
1712        dev->power.links_count--;
1713        spin_unlock_irq(&dev->power.lock);
1714}
1715
1716static bool pm_runtime_need_not_resume(struct device *dev)
1717{
1718        return atomic_read(&dev->power.usage_count) <= 1 &&
1719                (atomic_read(&dev->power.child_count) == 0 ||
1720                 dev->power.ignore_children);
1721}
1722
1723/**
1724 * pm_runtime_force_suspend - Force a device into suspend state if needed.
1725 * @dev: Device to suspend.
1726 *
1727 * Disable runtime PM so we safely can check the device's runtime PM status and
1728 * if it is active, invoke its ->runtime_suspend callback to suspend it and
1729 * change its runtime PM status field to RPM_SUSPENDED.  Also, if the device's
1730 * usage and children counters don't indicate that the device was in use before
1731 * the system-wide transition under way, decrement its parent's children counter
1732 * (if there is a parent).  Keep runtime PM disabled to preserve the state
1733 * unless we encounter errors.
1734 *
1735 * Typically this function may be invoked from a system suspend callback to make
1736 * sure the device is put into low power state and it should only be used during
1737 * system-wide PM transitions to sleep states.  It assumes that the analogous
1738 * pm_runtime_force_resume() will be used to resume the device.
1739 */
1740int pm_runtime_force_suspend(struct device *dev)
1741{
1742        int (*callback)(struct device *);
1743        int ret;
1744
1745        pm_runtime_disable(dev);
1746        if (pm_runtime_status_suspended(dev))
1747                return 0;
1748
1749        callback = RPM_GET_CALLBACK(dev, runtime_suspend);
1750
1751        ret = callback ? callback(dev) : 0;
1752        if (ret)
1753                goto err;
1754
1755        /*
1756         * If the device can stay in suspend after the system-wide transition
1757         * to the working state that will follow, drop the children counter of
1758         * its parent, but set its status to RPM_SUSPENDED anyway in case this
1759         * function will be called again for it in the meantime.
1760         */
1761        if (pm_runtime_need_not_resume(dev))
1762                pm_runtime_set_suspended(dev);
1763        else
1764                __update_runtime_status(dev, RPM_SUSPENDED);
1765
1766        return 0;
1767
1768err:
1769        pm_runtime_enable(dev);
1770        return ret;
1771}
1772EXPORT_SYMBOL_GPL(pm_runtime_force_suspend);
1773
1774/**
1775 * pm_runtime_force_resume - Force a device into resume state if needed.
1776 * @dev: Device to resume.
1777 *
1778 * Prior invoking this function we expect the user to have brought the device
1779 * into low power state by a call to pm_runtime_force_suspend(). Here we reverse
1780 * those actions and bring the device into full power, if it is expected to be
1781 * used on system resume.  In the other case, we defer the resume to be managed
1782 * via runtime PM.
1783 *
1784 * Typically this function may be invoked from a system resume callback.
1785 */
1786int pm_runtime_force_resume(struct device *dev)
1787{
1788        int (*callback)(struct device *);
1789        int ret = 0;
1790
1791        if (!pm_runtime_status_suspended(dev) || pm_runtime_need_not_resume(dev))
1792                goto out;
1793
1794        /*
1795         * The value of the parent's children counter is correct already, so
1796         * just update the status of the device.
1797         */
1798        __update_runtime_status(dev, RPM_ACTIVE);
1799
1800        callback = RPM_GET_CALLBACK(dev, runtime_resume);
1801
1802        ret = callback ? callback(dev) : 0;
1803        if (ret) {
1804                pm_runtime_set_suspended(dev);
1805                goto out;
1806        }
1807
1808        pm_runtime_mark_last_busy(dev);
1809out:
1810        pm_runtime_enable(dev);
1811        return ret;
1812}
1813EXPORT_SYMBOL_GPL(pm_runtime_force_resume);
1814