drivers/base/power/runtime.c

   1 /*
   2  * drivers/base/power/runtime.c - Helper functions for device runtime PM
   3  *
   4  * Copyright (c) 2009 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
   5  * Copyright (C) 2010 Alan Stern <stern@rowland.harvard.edu>
   6  *
   7  * This file is released under the GPLv2.
   8  */
   9
  10 #include <linux/sched/mm.h>
  11 #include <linux/export.h>
  12 #include <linux/pm_runtime.h>
  13 #include <linux/pm_wakeirq.h>
  14 #include <trace/events/rpm.h>
  15
  16 #include "../base.h"
  17 #include "power.h"
  18
  19 typedef int (*pm_callback_t)(struct device *);
  20
  21 static pm_callback_t __rpm_get_callback(struct device *dev, size_t cb_offset)
  22 {
  23         pm_callback_t cb;
  24         const struct dev_pm_ops *ops;
  25
  26         if (dev->pm_domain)
  27                 ops = &dev->pm_domain->ops;
  28         else if (dev->type && dev->type->pm)
  29                 ops = dev->type->pm;
  30         else if (dev->class && dev->class->pm)
  31                 ops = dev->class->pm;
  32         else if (dev->bus && dev->bus->pm)
  33                 ops = dev->bus->pm;
  34         else
  35                 ops = NULL;
  36
  37         if (ops)
  38                 cb = *(pm_callback_t *)((void *)ops + cb_offset);
  39         else
  40                 cb = NULL;
  41
  42         if (!cb && dev->driver && dev->driver->pm)
  43                 cb = *(pm_callback_t *)((void *)dev->driver->pm + cb_offset);
  44
  45         return cb;
  46 }
  47
  48 #define RPM_GET_CALLBACK(dev, callback) \
  49                 __rpm_get_callback(dev, offsetof(struct dev_pm_ops, callback))
  50
  51 static int rpm_resume(struct device *dev, int rpmflags);
  52 static int rpm_suspend(struct device *dev, int rpmflags);
  53
  54 /**
  55  * update_pm_runtime_accounting - Update the time accounting of power states
  56  * @dev: Device to update the accounting for
  57  *
  58  * In order to be able to have time accounting of the various power states
  59  * (as used by programs such as PowerTOP to show the effectiveness of runtime
  60  * PM), we need to track the time spent in each state.
  61  * update_pm_runtime_accounting must be called each time before the
  62  * runtime_status field is updated, to account the time in the old state
  63  * correctly.
  64  */
  65 void update_pm_runtime_accounting(struct device *dev)
  66 {
  67         unsigned long now = jiffies;
  68         unsigned long delta;
  69
  70         delta = now - dev->power.accounting_timestamp;
  71
  72         dev->power.accounting_timestamp = now;
  73
  74         if (dev->power.disable_depth > 0)
  75                 return;
  76
  77         if (dev->power.runtime_status == RPM_SUSPENDED)
  78                 dev->power.suspended_jiffies += delta;
  79         else
  80                 dev->power.active_jiffies += delta;
  81 }
  82
  83 static void __update_runtime_status(struct device *dev, enum rpm_status status)
  84 {
  85         update_pm_runtime_accounting(dev);
  86         dev->power.runtime_status = status;
  87 }
  88
  89 /**
  90  * pm_runtime_deactivate_timer - Deactivate given device's suspend timer.
  91  * @dev: Device to handle.
  92  */
  93 static void pm_runtime_deactivate_timer(struct device *dev)
  94 {
  95         if (dev->power.timer_expires > 0) {
  96                 del_timer(&dev->power.suspend_timer);
  97                 dev->power.timer_expires = 0;
  98         }
  99 }
 100
 101 /**
 102  * pm_runtime_cancel_pending - Deactivate suspend timer and cancel requests.
 103  * @dev: Device to handle.
 104  */
 105 static void pm_runtime_cancel_pending(struct device *dev)
 106 {
 107         pm_runtime_deactivate_timer(dev);
 108         /*
 109          * In case there's a request pending, make sure its work function will
 110          * return without doing anything.
 111          */
 112         dev->power.request = RPM_REQ_NONE;
 113 }
 114
 115 /*
 116  * pm_runtime_autosuspend_expiration - Get a device's autosuspend-delay expiration time.
 117  * @dev: Device to handle.
 118  *
 119  * Compute the autosuspend-delay expiration time based on the device's
 120  * power.last_busy time.  If the delay has already expired or is disabled
 121  * (negative) or the power.use_autosuspend flag isn't set, return 0.
 122  * Otherwise return the expiration time in jiffies (adjusted to be nonzero).
 123  *
 124  * This function may be called either with or without dev->power.lock held.
 125  * Either way it can be racy, since power.last_busy may be updated at any time.
 126  */
 127 unsigned long pm_runtime_autosuspend_expiration(struct device *dev)
 128 {
 129         int autosuspend_delay;
 130         long elapsed;
 131         unsigned long last_busy;
 132         unsigned long expires = 0;
 133
 134         if (!dev->power.use_autosuspend)
 135                 goto out;
 136
 137         autosuspend_delay = READ_ONCE(dev->power.autosuspend_delay);
 138         if (autosuspend_delay < 0)
 139                 goto out;
 140
 141         last_busy = READ_ONCE(dev->power.last_busy);
 142         elapsed = jiffies - last_busy;
 143         if (elapsed < 0)
 144                 goto out;       /* jiffies has wrapped around. */
 145
 146         /*
 147          * If the autosuspend_delay is >= 1 second, align the timer by rounding
 148          * up to the nearest second.
 149          */
 150         expires = last_busy + msecs_to_jiffies(autosuspend_delay);
 151         if (autosuspend_delay >= 1000)
 152                 expires = round_jiffies(expires);
 153         expires += !expires;
 154         if (elapsed >= expires - last_busy)
 155                 expires = 0;    /* Already expired. */
 156
 157  out:
 158         return expires;
 159 }
 160 EXPORT_SYMBOL_GPL(pm_runtime_autosuspend_expiration);
 161
 162 static int dev_memalloc_noio(struct device *dev, void *data)
 163 {
 164         return dev->power.memalloc_noio;
 165 }
 166
 167 /*
 168  * pm_runtime_set_memalloc_noio - Set a device's memalloc_noio flag.
 169  * @dev: Device to handle.
 170  * @enable: True for setting the flag and False for clearing the flag.
 171  *
 172  * Set the flag for all devices in the path from the device to the
 173  * root device in the device tree if @enable is true, otherwise clear
 174  * the flag for devices in the path whose siblings don't set the flag.
 175  *
 176  * The function should only be called by block device, or network
 177  * device driver for solving the deadlock problem during runtime
 178  * resume/suspend:
 179  *
 180  *     If memory allocation with GFP_KERNEL is called inside runtime
 181  *     resume/suspend callback of any one of its ancestors(or the
 182  *     block device itself), the deadlock may be triggered inside the
 183  *     memory allocation since it might not complete until the block
 184  *     device becomes active and the involed page I/O finishes. The
 185  *     situation is pointed out first by Alan Stern. Network device
 186  *     are involved in iSCSI kind of situation.
 187  *
 188  * The lock of dev_hotplug_mutex is held in the function for handling
 189  * hotplug race because pm_runtime_set_memalloc_noio() may be called
 190  * in async probe().
 191  *
 192  * The function should be called between device_add() and device_del()
 193  * on the affected device(block/network device).
 194  */
 195 void pm_runtime_set_memalloc_noio(struct device *dev, bool enable)
 196 {
 197         static DEFINE_MUTEX(dev_hotplug_mutex);
 198
 199         mutex_lock(&dev_hotplug_mutex);
 200         for (;;) {
 201                 bool enabled;
 202
 203                 /* hold power lock since bitfield is not SMP-safe. */
 204                 spin_lock_irq(&dev->power.lock);
 205                 enabled = dev->power.memalloc_noio;
 206                 dev->power.memalloc_noio = enable;
 207                 spin_unlock_irq(&dev->power.lock);
 208
 209                 /*
 210                  * not need to enable ancestors any more if the device
 211                  * has been enabled.
 212                  */
 213                 if (enabled && enable)
 214                         break;
 215
 216                 dev = dev->parent;
 217
 218                 /*
 219                  * clear flag of the parent device only if all the
 220                  * children don't set the flag because ancestor's
 221                  * flag was set by any one of the descendants.
 222                  */
 223                 if (!dev || (!enable &&
 224                              device_for_each_child(dev, NULL,
 225                                                    dev_memalloc_noio)))
 226                         break;
 227         }
 228         mutex_unlock(&dev_hotplug_mutex);
 229 }
 230 EXPORT_SYMBOL_GPL(pm_runtime_set_memalloc_noio);
 231
 232 /**
 233  * rpm_check_suspend_allowed - Test whether a device may be suspended.
 234  * @dev: Device to test.
 235  */
 236 static int rpm_check_suspend_allowed(struct device *dev)
 237 {
 238         int retval = 0;
 239
 240         if (dev->power.runtime_error)
 241                 retval = -EINVAL;
 242         else if (dev->power.disable_depth > 0)
 243                 retval = -EACCES;
 244         else if (atomic_read(&dev->power.usage_count) > 0)
 245                 retval = -EAGAIN;
 246         else if (!dev->power.ignore_children &&
 247                         atomic_read(&dev->power.child_count))
 248                 retval = -EBUSY;
 249
 250         /* Pending resume requests take precedence over suspends. */
 251         else if ((dev->power.deferred_resume
 252                         && dev->power.runtime_status == RPM_SUSPENDING)
 253             || (dev->power.request_pending
 254                         && dev->power.request == RPM_REQ_RESUME))
 255                 retval = -EAGAIN;
 256         else if (__dev_pm_qos_read_value(dev) == 0)
 257                 retval = -EPERM;
 258         else if (dev->power.runtime_status == RPM_SUSPENDED)
 259                 retval = 1;
 260
 261         return retval;
 262 }
 263
 264 static int rpm_get_suppliers(struct device *dev)
 265 {
 266         struct device_link *link;
 267
 268         list_for_each_entry_rcu(link, &dev->links.suppliers, c_node) {
 269                 int retval;
 270
 271                 if (!(link->flags & DL_FLAG_PM_RUNTIME) ||
 272                     READ_ONCE(link->status) == DL_STATE_SUPPLIER_UNBIND)
 273                         continue;
 274
 275                 retval = pm_runtime_get_sync(link->supplier);
 276                 /* Ignore suppliers with disabled runtime PM. */
 277                 if (retval < 0 && retval != -EACCES) {
 278                         pm_runtime_put_noidle(link->supplier);
 279                         return retval;
 280                 }
 281                 refcount_inc(&link->rpm_active);
 282         }
 283         return 0;
 284 }
 285
 286 static void rpm_put_suppliers(struct device *dev)
 287 {
 288         struct device_link *link;
 289
 290         list_for_each_entry_rcu(link, &dev->links.suppliers, c_node) {
 291                 if (READ_ONCE(link->status) == DL_STATE_SUPPLIER_UNBIND)
 292                         continue;
 293
 294                 while (refcount_dec_not_one(&link->rpm_active))
 295                         pm_runtime_put(link->supplier);
 296         }
 297 }
 298
 299 /**
 300  * __rpm_callback - Run a given runtime PM callback for a given device.
 301  * @cb: Runtime PM callback to run.
 302  * @dev: Device to run the callback for.
 303  */
 304 static int __rpm_callback(int (*cb)(struct device *), struct device *dev)
 305         __releases(&dev->power.lock) __acquires(&dev->power.lock)
 306 {
 307         int retval, idx;
 308         bool use_links = dev->power.links_count > 0;
 309
 310         if (dev->power.irq_safe) {
 311                 spin_unlock(&dev->power.lock);
 312         } else {
 313                 spin_unlock_irq(&dev->power.lock);
 314
 315                 /*
 316                  * Resume suppliers if necessary.
 317                  *
 318                  * The device's runtime PM status cannot change until this
 319                  * routine returns, so it is safe to read the status outside of
 320                  * the lock.
 321                  */
 322                 if (use_links && dev->power.runtime_status == RPM_RESUMING) {
 323                         idx = device_links_read_lock();
 324
 325                         retval = rpm_get_suppliers(dev);
 326                         if (retval)
 327                                 goto fail;
 328
 329                         device_links_read_unlock(idx);
 330                 }
 331         }
 332
 333         retval = cb(dev);
 334
 335         if (dev->power.irq_safe) {
 336                 spin_lock(&dev->power.lock);
 337         } else {
 338                 /*
 339                  * If the device is suspending and the callback has returned
 340                  * success, drop the usage counters of the suppliers that have
 341                  * been reference counted on its resume.
 342                  *
 343                  * Do that if resume fails too.
 344                  */
 345                 if (use_links
 346                     && ((dev->power.runtime_status == RPM_SUSPENDING && !retval)
 347                     || (dev->power.runtime_status == RPM_RESUMING && retval))) {
 348                         idx = device_links_read_lock();
 349
 350  fail:
 351                         rpm_put_suppliers(dev);
 352
 353                         device_links_read_unlock(idx);
 354                 }
 355
 356                 spin_lock_irq(&dev->power.lock);
 357         }
 358
 359         return retval;
 360 }
 361
 362 /**
 363  * rpm_idle - Notify device bus type if the device can be suspended.
 364  * @dev: Device to notify the bus type about.
 365  * @rpmflags: Flag bits.
 366  *
 367  * Check if the device's runtime PM status allows it to be suspended.  If
 368  * another idle notification has been started earlier, return immediately.  If
 369  * the RPM_ASYNC flag is set then queue an idle-notification request; otherwise
 370  * run the ->runtime_idle() callback directly. If the ->runtime_idle callback
 371  * doesn't exist or if it returns 0, call rpm_suspend with the RPM_AUTO flag.
 372  *
 373  * This function must be called under dev->power.lock with interrupts disabled.
 374  */
 375 static int rpm_idle(struct device *dev, int rpmflags)
 376 {
 377         int (*callback)(struct device *);
 378         int retval;
 379
 380         trace_rpm_idle_rcuidle(dev, rpmflags);
 381         retval = rpm_check_suspend_allowed(dev);
 382         if (retval < 0)
 383                 ;       /* Conditions are wrong. */
 384
 385         /* Idle notifications are allowed only in the RPM_ACTIVE state. */
 386         else if (dev->power.runtime_status != RPM_ACTIVE)
 387                 retval = -EAGAIN;
 388
 389         /*
 390          * Any pending request other than an idle notification takes
 391          * precedence over us, except that the timer may be running.
 392          */
 393         else if (dev->power.request_pending &&
 394             dev->power.request > RPM_REQ_IDLE)
 395                 retval = -EAGAIN;
 396
 397         /* Act as though RPM_NOWAIT is always set. */
 398         else if (dev->power.idle_notification)
 399                 retval = -EINPROGRESS;
 400         if (retval)
 401                 goto out;
 402
 403         /* Pending requests need to be canceled. */
 404         dev->power.request = RPM_REQ_NONE;
 405
 406         if (dev->power.no_callbacks)
 407                 goto out;
 408
 409         /* Carry out an asynchronous or a synchronous idle notification. */
 410         if (rpmflags & RPM_ASYNC) {
 411                 dev->power.request = RPM_REQ_IDLE;
 412                 if (!dev->power.request_pending) {
 413                         dev->power.request_pending = true;
 414                         queue_work(pm_wq, &dev->power.work);
 415                 }
 416                 trace_rpm_return_int_rcuidle(dev, _THIS_IP_, 0);
 417                 return 0;
 418         }
 419
 420         dev->power.idle_notification = true;
 421
 422         callback = RPM_GET_CALLBACK(dev, runtime_idle);
 423
 424         if (callback)
 425                 retval = __rpm_callback(callback, dev);
 426
 427         dev->power.idle_notification = false;
 428         wake_up_all(&dev->power.wait_queue);
 429
 430  out:
 431         trace_rpm_return_int_rcuidle(dev, _THIS_IP_, retval);
 432         return retval ? retval : rpm_suspend(dev, rpmflags | RPM_AUTO);
 433 }
 434
 435 /**
 436  * rpm_callback - Run a given runtime PM callback for a given device.
 437  * @cb: Runtime PM callback to run.
 438  * @dev: Device to run the callback for.
 439  */
 440 static int rpm_callback(int (*cb)(struct device *), struct device *dev)
 441 {
 442         int retval;
 443
 444         if (!cb)
 445                 return -ENOSYS;
 446
 447         if (dev->power.memalloc_noio) {
 448                 unsigned int noio_flag;
 449
 450                 /*
 451                  * Deadlock might be caused if memory allocation with
 452                  * GFP_KERNEL happens inside runtime_suspend and
 453                  * runtime_resume callbacks of one block device's
 454                  * ancestor or the block device itself. Network
 455                  * device might be thought as part of iSCSI block
 456                  * device, so network device and its ancestor should
 457                  * be marked as memalloc_noio too.
 458                  */
 459                 noio_flag = memalloc_noio_save();
 460                 retval = __rpm_callback(cb, dev);
 461                 memalloc_noio_restore(noio_flag);
 462         } else {
 463                 retval = __rpm_callback(cb, dev);
 464         }
 465
 466         dev->power.runtime_error = retval;
 467         return retval != -EACCES ? retval : -EIO;
 468 }
 469
 470 /**
 471  * rpm_suspend - Carry out runtime suspend of given device.
 472  * @dev: Device to suspend.
 473  * @rpmflags: Flag bits.
 474  *
 475  * Check if the device's runtime PM status allows it to be suspended.
 476  * Cancel a pending idle notification, autosuspend or suspend. If
 477  * another suspend has been started earlier, either return immediately
 478  * or wait for it to finish, depending on the RPM_NOWAIT and RPM_ASYNC
 479  * flags. If the RPM_ASYNC flag is set then queue a suspend request;
 480  * otherwise run the ->runtime_suspend() callback directly. When
 481  * ->runtime_suspend succeeded, if a deferred resume was requested while
 482  * the callback was running then carry it out, otherwise send an idle
 483  * notification for its parent (if the suspend succeeded and both
 484  * ignore_children of parent->power and irq_safe of dev->power are not set).
 485  * If ->runtime_suspend failed with -EAGAIN or -EBUSY, and if the RPM_AUTO
 486  * flag is set and the next autosuspend-delay expiration time is in the
 487  * future, schedule another autosuspend attempt.
 488  *
 489  * This function must be called under dev->power.lock with interrupts disabled.
 490  */
 491 static int rpm_suspend(struct device *dev, int rpmflags)
 492         __releases(&dev->power.lock) __acquires(&dev->power.lock)
 493 {
 494         int (*callback)(struct device *);
 495         struct device *parent = NULL;
 496         int retval;
 497
 498         trace_rpm_suspend_rcuidle(dev, rpmflags);
 499
 500  repeat:
 501         retval = rpm_check_suspend_allowed(dev);
 502
 503         if (retval < 0)
 504                 ;       /* Conditions are wrong. */
 505
 506         /* Synchronous suspends are not allowed in the RPM_RESUMING state. */
 507         else if (dev->power.runtime_status == RPM_RESUMING &&
 508             !(rpmflags & RPM_ASYNC))
 509                 retval = -EAGAIN;
 510         if (retval)
 511                 goto out;
 512
 513         /* If the autosuspend_delay time hasn't expired yet, reschedule. */
 514         if ((rpmflags & RPM_AUTO)
 515             && dev->power.runtime_status != RPM_SUSPENDING) {
 516                 unsigned long expires = pm_runtime_autosuspend_expiration(dev);
 517
 518                 if (expires != 0) {
 519                         /* Pending requests need to be canceled. */
 520                         dev->power.request = RPM_REQ_NONE;
 521
 522                         /*
 523                          * Optimization: If the timer is already running and is
 524                          * set to expire at or before the autosuspend delay,
 525                          * avoid the overhead of resetting it.  Just let it
 526                          * expire; pm_suspend_timer_fn() will take care of the
 527                          * rest.
 528                          */
 529                         if (!(dev->power.timer_expires && time_before_eq(
 530                             dev->power.timer_expires, expires))) {
 531                                 dev->power.timer_expires = expires;
 532                                 mod_timer(&dev->power.suspend_timer, expires);
 533                         }
 534                         dev->power.timer_autosuspends = 1;
 535                         goto out;
 536                 }
 537         }
 538
 539         /* Other scheduled or pending requests need to be canceled. */
 540         pm_runtime_cancel_pending(dev);
 541
 542         if (dev->power.runtime_status == RPM_SUSPENDING) {
 543                 DEFINE_WAIT(wait);
 544
 545                 if (rpmflags & (RPM_ASYNC | RPM_NOWAIT)) {
 546                         retval = -EINPROGRESS;
 547                         goto out;
 548                 }
 549
 550                 if (dev->power.irq_safe) {
 551                         spin_unlock(&dev->power.lock);
 552
 553                         cpu_relax();
 554
 555                         spin_lock(&dev->power.lock);
 556                         goto repeat;
 557                 }
 558
 559                 /* Wait for the other suspend running in parallel with us. */
 560                 for (;;) {
 561                         prepare_to_wait(&dev->power.wait_queue, &wait,
 562                                         TASK_UNINTERRUPTIBLE);
 563                         if (dev->power.runtime_status != RPM_SUSPENDING)
 564                                 break;
 565
 566                         spin_unlock_irq(&dev->power.lock);
 567
 568                         schedule();
 569
 570                         spin_lock_irq(&dev->power.lock);
 571                 }
 572                 finish_wait(&dev->power.wait_queue, &wait);
 573                 goto repeat;
 574         }
 575
 576         if (dev->power.no_callbacks)
 577                 goto no_callback;       /* Assume success. */
 578
 579         /* Carry out an asynchronous or a synchronous suspend. */
 580         if (rpmflags & RPM_ASYNC) {
 581                 dev->power.request = (rpmflags & RPM_AUTO) ?
 582                     RPM_REQ_AUTOSUSPEND : RPM_REQ_SUSPEND;
 583                 if (!dev->power.request_pending) {
 584                         dev->power.request_pending = true;
 585                         queue_work(pm_wq, &dev->power.work);
 586                 }
 587                 goto out;
 588         }
 589
 590         __update_runtime_status(dev, RPM_SUSPENDING);
 591
 592         callback = RPM_GET_CALLBACK(dev, runtime_suspend);
 593
 594         dev_pm_enable_wake_irq_check(dev, true);
 595         retval = rpm_callback(callback, dev);
 596         if (retval)
 597                 goto fail;
 598
 599  no_callback:
 600         __update_runtime_status(dev, RPM_SUSPENDED);
 601         pm_runtime_deactivate_timer(dev);
 602
 603         if (dev->parent) {
 604                 parent = dev->parent;
 605                 atomic_add_unless(&parent->power.child_count, -1, 0);
 606         }
 607         wake_up_all(&dev->power.wait_queue);
 608
 609         if (dev->power.deferred_resume) {
 610                 dev->power.deferred_resume = false;
 611                 rpm_resume(dev, 0);
 612                 retval = -EAGAIN;
 613                 goto out;
 614         }
 615
 616         /* Maybe the parent is now able to suspend. */
 617         if (parent && !parent->power.ignore_children && !dev->power.irq_safe) {
 618                 spin_unlock(&dev->power.lock);
 619
 620                 spin_lock(&parent->power.lock);
 621                 rpm_idle(parent, RPM_ASYNC);
 622                 spin_unlock(&parent->power.lock);
 623
 624                 spin_lock(&dev->power.lock);
 625         }
 626
 627  out:
 628         trace_rpm_return_int_rcuidle(dev, _THIS_IP_, retval);
 629
 630         return retval;
 631
 632  fail:
 633         dev_pm_disable_wake_irq_check(dev);
 634         __update_runtime_status(dev, RPM_ACTIVE);
 635         dev->power.deferred_resume = false;
 636         wake_up_all(&dev->power.wait_queue);
 637
 638         if (retval == -EAGAIN || retval == -EBUSY) {
 639                 dev->power.runtime_error = 0;
 640
 641                 /*
 642                  * If the callback routine failed an autosuspend, and
 643                  * if the last_busy time has been updated so that there
 644                  * is a new autosuspend expiration time, automatically
 645                  * reschedule another autosuspend.
 646                  */
 647                 if ((rpmflags & RPM_AUTO) &&
 648                     pm_runtime_autosuspend_expiration(dev) != 0)
 649                         goto repeat;
 650         } else {
 651                 pm_runtime_cancel_pending(dev);
 652         }
 653         goto out;
 654 }
 655
 656 /**
 657  * rpm_resume - Carry out runtime resume of given device.
 658  * @dev: Device to resume.
 659  * @rpmflags: Flag bits.
 660  *
 661  * Check if the device's runtime PM status allows it to be resumed.  Cancel
 662  * any scheduled or pending requests.  If another resume has been started
 663  * earlier, either return immediately or wait for it to finish, depending on the
 664  * RPM_NOWAIT and RPM_ASYNC flags.  Similarly, if there's a suspend running in
 665  * parallel with this function, either tell the other process to resume after
 666  * suspending (deferred_resume) or wait for it to finish.  If the RPM_ASYNC
 667  * flag is set then queue a resume request; otherwise run the
 668  * ->runtime_resume() callback directly.  Queue an idle notification for the
 669  * device if the resume succeeded.
 670  *
 671  * This function must be called under dev->power.lock with interrupts disabled.
 672  */
 673 static int rpm_resume(struct device *dev, int rpmflags)
 674         __releases(&dev->power.lock) __acquires(&dev->power.lock)
 675 {
 676         int (*callback)(struct device *);
 677         struct device *parent = NULL;
 678         int retval = 0;
 679
 680         trace_rpm_resume_rcuidle(dev, rpmflags);
 681
 682  repeat:
 683         if (dev->power.runtime_error)
 684                 retval = -EINVAL;
 685         else if (dev->power.disable_depth == 1 && dev->power.is_suspended
 686             && dev->power.runtime_status == RPM_ACTIVE)
 687                 retval = 1;
 688         else if (dev->power.disable_depth > 0)
 689                 retval = -EACCES;
 690         if (retval)
 691                 goto out;
 692
 693         /*
 694          * Other scheduled or pending requests need to be canceled.  Small
 695          * optimization: If an autosuspend timer is running, leave it running
 696          * rather than cancelling it now only to restart it again in the near
 697          * future.
 698          */
 699         dev->power.request = RPM_REQ_NONE;
 700         if (!dev->power.timer_autosuspends)
 701                 pm_runtime_deactivate_timer(dev);
 702
 703         if (dev->power.runtime_status == RPM_ACTIVE) {
 704                 retval = 1;
 705                 goto out;
 706         }
 707
 708         if (dev->power.runtime_status == RPM_RESUMING
 709             || dev->power.runtime_status == RPM_SUSPENDING) {
 710                 DEFINE_WAIT(wait);
 711
 712                 if (rpmflags & (RPM_ASYNC | RPM_NOWAIT)) {
 713                         if (dev->power.runtime_status == RPM_SUSPENDING)
 714                                 dev->power.deferred_resume = true;
 715                         else
 716                                 retval = -EINPROGRESS;
 717                         goto out;
 718                 }
 719
 720                 if (dev->power.irq_safe) {
 721                         spin_unlock(&dev->power.lock);
 722
 723                         cpu_relax();
 724
 725                         spin_lock(&dev->power.lock);
 726                         goto repeat;
 727                 }
 728
 729                 /* Wait for the operation carried out in parallel with us. */
 730                 for (;;) {
 731                         prepare_to_wait(&dev->power.wait_queue, &wait,
 732                                         TASK_UNINTERRUPTIBLE);
 733                         if (dev->power.runtime_status != RPM_RESUMING
 734                             && dev->power.runtime_status != RPM_SUSPENDING)
 735                                 break;
 736
 737                         spin_unlock_irq(&dev->power.lock);
 738
 739                         schedule();
 740
 741                         spin_lock_irq(&dev->power.lock);
 742                 }
 743                 finish_wait(&dev->power.wait_queue, &wait);
 744                 goto repeat;
 745         }
 746
 747         /*
 748          * See if we can skip waking up the parent.  This is safe only if
 749          * power.no_callbacks is set, because otherwise we don't know whether
 750          * the resume will actually succeed.
 751          */
 752         if (dev->power.no_callbacks && !parent && dev->parent) {
 753                 spin_lock_nested(&dev->parent->power.lock, SINGLE_DEPTH_NESTING);
 754                 if (dev->parent->power.disable_depth > 0
 755                     || dev->parent->power.ignore_children
 756                     || dev->parent->power.runtime_status == RPM_ACTIVE) {
 757                         atomic_inc(&dev->parent->power.child_count);
 758                         spin_unlock(&dev->parent->power.lock);
 759                         retval = 1;
 760                         goto no_callback;       /* Assume success. */
 761                 }
 762                 spin_unlock(&dev->parent->power.lock);
 763         }
 764
 765         /* Carry out an asynchronous or a synchronous resume. */
 766         if (rpmflags & RPM_ASYNC) {
 767                 dev->power.request = RPM_REQ_RESUME;
 768                 if (!dev->power.request_pending) {
 769                         dev->power.request_pending = true;
 770                         queue_work(pm_wq, &dev->power.work);
 771                 }
 772                 retval = 0;
 773                 goto out;
 774         }
 775
 776         if (!parent && dev->parent) {
 777                 /*
 778                  * Increment the parent's usage counter and resume it if
 779                  * necessary.  Not needed if dev is irq-safe; then the
 780                  * parent is permanently resumed.
 781                  */
 782                 parent = dev->parent;
 783                 if (dev->power.irq_safe)
 784                         goto skip_parent;
 785                 spin_unlock(&dev->power.lock);
 786
 787                 pm_runtime_get_noresume(parent);
 788
 789                 spin_lock(&parent->power.lock);
 790                 /*
 791                  * Resume the parent if it has runtime PM enabled and not been
 792                  * set to ignore its children.
 793                  */
 794                 if (!parent->power.disable_depth
 795                     && !parent->power.ignore_children) {
 796                         rpm_resume(parent, 0);
 797                         if (parent->power.runtime_status != RPM_ACTIVE)
 798                                 retval = -EBUSY;
 799                 }
 800                 spin_unlock(&parent->power.lock);
 801
 802                 spin_lock(&dev->power.lock);
 803                 if (retval)
 804                         goto out;
 805                 goto repeat;
 806         }
 807  skip_parent:
 808
 809         if (dev->power.no_callbacks)
 810                 goto no_callback;       /* Assume success. */
 811
 812         __update_runtime_status(dev, RPM_RESUMING);
 813
 814         callback = RPM_GET_CALLBACK(dev, runtime_resume);
 815
 816         dev_pm_disable_wake_irq_check(dev);
 817         retval = rpm_callback(callback, dev);
 818         if (retval) {
 819                 __update_runtime_status(dev, RPM_SUSPENDED);
 820                 pm_runtime_cancel_pending(dev);
 821                 dev_pm_enable_wake_irq_check(dev, false);
 822         } else {
 823  no_callback:
 824                 __update_runtime_status(dev, RPM_ACTIVE);
 825                 pm_runtime_mark_last_busy(dev);
 826                 if (parent)
 827                         atomic_inc(&parent->power.child_count);
 828         }
 829         wake_up_all(&dev->power.wait_queue);
 830
 831         if (retval >= 0)
 832                 rpm_idle(dev, RPM_ASYNC);
 833
 834  out:
 835         if (parent && !dev->power.irq_safe) {
 836                 spin_unlock_irq(&dev->power.lock);
 837
 838                 pm_runtime_put(parent);
 839
 840                 spin_lock_irq(&dev->power.lock);
 841         }
 842
 843         trace_rpm_return_int_rcuidle(dev, _THIS_IP_, retval);
 844
 845         return retval;
 846 }
 847
 848 /**
 849  * pm_runtime_work - Universal runtime PM work function.
 850  * @work: Work structure used for scheduling the execution of this function.
 851  *
 852  * Use @work to get the device object the work is to be done for, determine what
 853  * is to be done and execute the appropriate runtime PM function.
 854  */
 855 static void pm_runtime_work(struct work_struct *work)
 856 {
 857         struct device *dev = container_of(work, struct device, power.work);
 858         enum rpm_request req;
 859
 860         spin_lock_irq(&dev->power.lock);
 861
 862         if (!dev->power.request_pending)
 863                 goto out;
 864
 865         req = dev->power.request;
 866         dev->power.request = RPM_REQ_NONE;
 867         dev->power.request_pending = false;
 868
 869         switch (req) {
 870         case RPM_REQ_NONE:
 871                 break;
 872         case RPM_REQ_IDLE:
 873                 rpm_idle(dev, RPM_NOWAIT);
 874                 break;
 875         case RPM_REQ_SUSPEND:
 876                 rpm_suspend(dev, RPM_NOWAIT);
 877                 break;
 878         case RPM_REQ_AUTOSUSPEND:
 879                 rpm_suspend(dev, RPM_NOWAIT | RPM_AUTO);
 880                 break;
 881         case RPM_REQ_RESUME:
 882                 rpm_resume(dev, RPM_NOWAIT);
 883                 break;
 884         }
 885
 886  out:
 887         spin_unlock_irq(&dev->power.lock);
 888 }
 889
 890 /**
 891  * pm_suspend_timer_fn - Timer function for pm_schedule_suspend().
 892  * @data: Device pointer passed by pm_schedule_suspend().
 893  *
 894  * Check if the time is right and queue a suspend request.
 895  */
 896 static void pm_suspend_timer_fn(struct timer_list *t)
 897 {
 898         struct device *dev = from_timer(dev, t, power.suspend_timer);
 899         unsigned long flags;
 900         unsigned long expires;
 901
 902         spin_lock_irqsave(&dev->power.lock, flags);
 903
 904         expires = dev->power.timer_expires;
 905         /* If 'expire' is after 'jiffies' we've been called too early. */
 906         if (expires > 0 && !time_after(expires, jiffies)) {
 907                 dev->power.timer_expires = 0;
 908                 rpm_suspend(dev, dev->power.timer_autosuspends ?
 909                     (RPM_ASYNC | RPM_AUTO) : RPM_ASYNC);
 910         }
 911
 912         spin_unlock_irqrestore(&dev->power.lock, flags);
 913 }
 914
 915 /**
 916  * pm_schedule_suspend - Set up a timer to submit a suspend request in future.
 917  * @dev: Device to suspend.
 918  * @delay: Time to wait before submitting a suspend request, in milliseconds.
 919  */
 920 int pm_schedule_suspend(struct device *dev, unsigned int delay)
 921 {
 922         unsigned long flags;
 923         int retval;
 924
 925         spin_lock_irqsave(&dev->power.lock, flags);
 926
 927         if (!delay) {
 928                 retval = rpm_suspend(dev, RPM_ASYNC);
 929                 goto out;
 930         }
 931
 932         retval = rpm_check_suspend_allowed(dev);
 933         if (retval)
 934                 goto out;
 935
 936         /* Other scheduled or pending requests need to be canceled. */
 937         pm_runtime_cancel_pending(dev);
 938
 939         dev->power.timer_expires = jiffies + msecs_to_jiffies(delay);
 940         dev->power.timer_expires += !dev->power.timer_expires;
 941         dev->power.timer_autosuspends = 0;
 942         mod_timer(&dev->power.suspend_timer, dev->power.timer_expires);
 943
 944  out:
 945         spin_unlock_irqrestore(&dev->power.lock, flags);
 946
 947         return retval;
 948 }
 949 EXPORT_SYMBOL_GPL(pm_schedule_suspend);
 950
 951 /**
 952  * __pm_runtime_idle - Entry point for runtime idle operations.
 953  * @dev: Device to send idle notification for.
 954  * @rpmflags: Flag bits.
 955  *
 956  * If the RPM_GET_PUT flag is set, decrement the device's usage count and
 957  * return immediately if it is larger than zero.  Then carry out an idle
 958  * notification, either synchronous or asynchronous.
 959  *
 960  * This routine may be called in atomic context if the RPM_ASYNC flag is set,
 961  * or if pm_runtime_irq_safe() has been called.
 962  */
 963 int __pm_runtime_idle(struct device *dev, int rpmflags)
 964 {
 965         unsigned long flags;
 966         int retval;
 967
 968         if (rpmflags & RPM_GET_PUT) {
 969                 if (!atomic_dec_and_test(&dev->power.usage_count))
 970                         return 0;
 971         }
 972
 973         might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);
 974
 975         spin_lock_irqsave(&dev->power.lock, flags);
 976         retval = rpm_idle(dev, rpmflags);
 977         spin_unlock_irqrestore(&dev->power.lock, flags);
 978
 979         return retval;
 980 }
 981 EXPORT_SYMBOL_GPL(__pm_runtime_idle);
 982
 983 /**
 984  * __pm_runtime_suspend - Entry point for runtime put/suspend operations.
 985  * @dev: Device to suspend.
 986  * @rpmflags: Flag bits.
 987  *
 988  * If the RPM_GET_PUT flag is set, decrement the device's usage count and
 989  * return immediately if it is larger than zero.  Then carry out a suspend,
 990  * either synchronous or asynchronous.
 991  *
 992  * This routine may be called in atomic context if the RPM_ASYNC flag is set,
 993  * or if pm_runtime_irq_safe() has been called.
 994  */
 995 int __pm_runtime_suspend(struct device *dev, int rpmflags)
 996 {
 997         unsigned long flags;
 998         int retval;
 999
1000         if (rpmflags & RPM_GET_PUT) {
1001                 if (!atomic_dec_and_test(&dev->power.usage_count))
1002                         return 0;
1003         }
1004
1005         might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);
1006
1007         spin_lock_irqsave(&dev->power.lock, flags);
1008         retval = rpm_suspend(dev, rpmflags);
1009         spin_unlock_irqrestore(&dev->power.lock, flags);
1010
1011         return retval;
1012 }
1013 EXPORT_SYMBOL_GPL(__pm_runtime_suspend);
1014
1015 /**
1016  * __pm_runtime_resume - Entry point for runtime resume operations.
1017  * @dev: Device to resume.
1018  * @rpmflags: Flag bits.
1019  *
1020  * If the RPM_GET_PUT flag is set, increment the device's usage count.  Then
1021  * carry out a resume, either synchronous or asynchronous.
1022  *
1023  * This routine may be called in atomic context if the RPM_ASYNC flag is set,
1024  * or if pm_runtime_irq_safe() has been called.
1025  */
1026 int __pm_runtime_resume(struct device *dev, int rpmflags)
1027 {
1028         unsigned long flags;
1029         int retval;
1030
1031         might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe &&
1032                         dev->power.runtime_status != RPM_ACTIVE);
1033
1034         if (rpmflags & RPM_GET_PUT)
1035                 atomic_inc(&dev->power.usage_count);
1036
1037         spin_lock_irqsave(&dev->power.lock, flags);
1038         retval = rpm_resume(dev, rpmflags);
1039         spin_unlock_irqrestore(&dev->power.lock, flags);
1040
1041         return retval;
1042 }
1043 EXPORT_SYMBOL_GPL(__pm_runtime_resume);
1044
1045 /**
1046  * pm_runtime_get_if_in_use - Conditionally bump up the device's usage counter.
1047  * @dev: Device to handle.
1048  *
1049  * Return -EINVAL if runtime PM is disabled for the device.
1050  *
1051  * If that's not the case and if the device's runtime PM status is RPM_ACTIVE
1052  * and the runtime PM usage counter is nonzero, increment the counter and
1053  * return 1.  Otherwise return 0 without changing the counter.
1054  */
1055 int pm_runtime_get_if_in_use(struct device *dev)
1056 {
1057         unsigned long flags;
1058         int retval;
1059
1060         spin_lock_irqsave(&dev->power.lock, flags);
1061         retval = dev->power.disable_depth > 0 ? -EINVAL :
1062                 dev->power.runtime_status == RPM_ACTIVE
1063                         && atomic_inc_not_zero(&dev->power.usage_count);
1064         spin_unlock_irqrestore(&dev->power.lock, flags);
1065         return retval;
1066 }
1067 EXPORT_SYMBOL_GPL(pm_runtime_get_if_in_use);
1068
1069 /**
1070  * __pm_runtime_set_status - Set runtime PM status of a device.
1071  * @dev: Device to handle.
1072  * @status: New runtime PM status of the device.
1073  *
1074  * If runtime PM of the device is disabled or its power.runtime_error field is
1075  * different from zero, the status may be changed either to RPM_ACTIVE, or to
1076  * RPM_SUSPENDED, as long as that reflects the actual state of the device.
1077  * However, if the device has a parent and the parent is not active, and the
1078  * parent's power.ignore_children flag is unset, the device's status cannot be
1079  * set to RPM_ACTIVE, so -EBUSY is returned in that case.
1080  *
1081  * If successful, __pm_runtime_set_status() clears the power.runtime_error field
1082  * and the device parent's counter of unsuspended children is modified to
1083  * reflect the new status.  If the new status is RPM_SUSPENDED, an idle
1084  * notification request for the parent is submitted.
1085  */
1086 int __pm_runtime_set_status(struct device *dev, unsigned int status)
1087 {
1088         struct device *parent = dev->parent;
1089         unsigned long flags;
1090         bool notify_parent = false;
1091         int error = 0;
1092
1093         if (status != RPM_ACTIVE && status != RPM_SUSPENDED)
1094                 return -EINVAL;
1095
1096         spin_lock_irqsave(&dev->power.lock, flags);
1097
1098         if (!dev->power.runtime_error && !dev->power.disable_depth) {
1099                 error = -EAGAIN;
1100                 goto out;
1101         }
1102
1103         if (dev->power.runtime_status == status || !parent)
1104                 goto out_set;
1105
1106         if (status == RPM_SUSPENDED) {
1107                 atomic_add_unless(&parent->power.child_count, -1, 0);
1108                 notify_parent = !parent->power.ignore_children;
1109         } else {
1110                 spin_lock_nested(&parent->power.lock, SINGLE_DEPTH_NESTING);
1111
1112                 /*
1113                  * It is invalid to put an active child under a parent that is
1114                  * not active, has runtime PM enabled and the
1115                  * 'power.ignore_children' flag unset.
1116                  */
1117                 if (!parent->power.disable_depth
1118                     && !parent->power.ignore_children
1119                     && parent->power.runtime_status != RPM_ACTIVE) {
1120                         dev_err(dev, "runtime PM trying to activate child device %s but parent (%s) is not active\n",
1121                                 dev_name(dev),
1122                                 dev_name(parent));
1123                         error = -EBUSY;
1124                 } else if (dev->power.runtime_status == RPM_SUSPENDED) {
1125                         atomic_inc(&parent->power.child_count);
1126                 }
1127
1128                 spin_unlock(&parent->power.lock);
1129
1130                 if (error)
1131                         goto out;
1132         }
1133
1134  out_set:
1135         __update_runtime_status(dev, status);
1136         dev->power.runtime_error = 0;
1137  out:
1138         spin_unlock_irqrestore(&dev->power.lock, flags);
1139
1140         if (notify_parent)
1141                 pm_request_idle(parent);
1142
1143         return error;
1144 }
1145 EXPORT_SYMBOL_GPL(__pm_runtime_set_status);
1146
1147 /**
1148  * __pm_runtime_barrier - Cancel pending requests and wait for completions.
1149  * @dev: Device to handle.
1150  *
1151  * Flush all pending requests for the device from pm_wq and wait for all
1152  * runtime PM operations involving the device in progress to complete.
1153  *
1154  * Should be called under dev->power.lock with interrupts disabled.
1155  */
1156 static void __pm_runtime_barrier(struct device *dev)
1157 {
1158         pm_runtime_deactivate_timer(dev);
1159
1160         if (dev->power.request_pending) {
1161                 dev->power.request = RPM_REQ_NONE;
1162                 spin_unlock_irq(&dev->power.lock);
1163
1164                 cancel_work_sync(&dev->power.work);
1165
1166                 spin_lock_irq(&dev->power.lock);
1167                 dev->power.request_pending = false;
1168         }
1169
1170         if (dev->power.runtime_status == RPM_SUSPENDING
1171             || dev->power.runtime_status == RPM_RESUMING
1172             || dev->power.idle_notification) {
1173                 DEFINE_WAIT(wait);
1174
1175                 /* Suspend, wake-up or idle notification in progress. */
1176                 for (;;) {
1177                         prepare_to_wait(&dev->power.wait_queue, &wait,
1178                                         TASK_UNINTERRUPTIBLE);
1179                         if (dev->power.runtime_status != RPM_SUSPENDING
1180                             && dev->power.runtime_status != RPM_RESUMING
1181                             && !dev->power.idle_notification)
1182                                 break;
1183                         spin_unlock_irq(&dev->power.lock);
1184
1185                         schedule();
1186
1187                         spin_lock_irq(&dev->power.lock);
1188                 }
1189                 finish_wait(&dev->power.wait_queue, &wait);
1190         }
1191 }
1192
1193 /**
1194  * pm_runtime_barrier - Flush pending requests and wait for completions.
1195  * @dev: Device to handle.
1196  *
1197  * Prevent the device from being suspended by incrementing its usage counter and
1198  * if there's a pending resume request for the device, wake the device up.
1199  * Next, make sure that all pending requests for the device have been flushed
1200  * from pm_wq and wait for all runtime PM operations involving the device in
1201  * progress to complete.
1202  *
1203  * Return value:
1204  * 1, if there was a resume request pending and the device had to be woken up,
1205  * 0, otherwise
1206  */
1207 int pm_runtime_barrier(struct device *dev)
1208 {
1209         int retval = 0;
1210
1211         pm_runtime_get_noresume(dev);
1212         spin_lock_irq(&dev->power.lock);
1213
1214         if (dev->power.request_pending
1215             && dev->power.request == RPM_REQ_RESUME) {
1216                 rpm_resume(dev, 0);
1217                 retval = 1;
1218         }
1219
1220         __pm_runtime_barrier(dev);
1221
1222         spin_unlock_irq(&dev->power.lock);
1223         pm_runtime_put_noidle(dev);
1224
1225         return retval;
1226 }
1227 EXPORT_SYMBOL_GPL(pm_runtime_barrier);
1228
1229 /**
1230  * __pm_runtime_disable - Disable runtime PM of a device.
1231  * @dev: Device to handle.
1232  * @check_resume: If set, check if there's a resume request for the device.
1233  *
1234  * Increment power.disable_depth for the device and if it was zero previously,
1235  * cancel all pending runtime PM requests for the device and wait for all
1236  * operations in progress to complete.  The device can be either active or
1237  * suspended after its runtime PM has been disabled.
1238  *
1239  * If @check_resume is set and there's a resume request pending when
1240  * __pm_runtime_disable() is called and power.disable_depth is zero, the
1241  * function will wake up the device before disabling its runtime PM.
1242  */
1243 void __pm_runtime_disable(struct device *dev, bool check_resume)
1244 {
1245         spin_lock_irq(&dev->power.lock);
1246
1247         if (dev->power.disable_depth > 0) {
1248                 dev->power.disable_depth++;
1249                 goto out;
1250         }
1251
1252         /*
1253          * Wake up the device if there's a resume request pending, because that
1254          * means there probably is some I/O to process and disabling runtime PM
1255          * shouldn't prevent the device from processing the I/O.
1256          */
1257         if (check_resume && dev->power.request_pending
1258             && dev->power.request == RPM_REQ_RESUME) {
1259                 /*
1260                  * Prevent suspends and idle notifications from being carried
1261                  * out after we have woken up the device.
1262                  */
1263                 pm_runtime_get_noresume(dev);
1264
1265                 rpm_resume(dev, 0);
1266
1267                 pm_runtime_put_noidle(dev);
1268         }
1269
1270         if (!dev->power.disable_depth++)
1271                 __pm_runtime_barrier(dev);
1272
1273  out:
1274         spin_unlock_irq(&dev->power.lock);
1275 }
1276 EXPORT_SYMBOL_GPL(__pm_runtime_disable);
1277
1278 /**
1279  * pm_runtime_enable - Enable runtime PM of a device.
1280  * @dev: Device to handle.
1281  */
1282 void pm_runtime_enable(struct device *dev)
1283 {
1284         unsigned long flags;
1285
1286         spin_lock_irqsave(&dev->power.lock, flags);
1287
1288         if (dev->power.disable_depth > 0)
1289                 dev->power.disable_depth--;
1290         else
1291                 dev_warn(dev, "Unbalanced %s!\n", __func__);
1292
1293         WARN(!dev->power.disable_depth &&
1294              dev->power.runtime_status == RPM_SUSPENDED &&
1295              !dev->power.ignore_children &&
1296              atomic_read(&dev->power.child_count) > 0,
1297              "Enabling runtime PM for inactive device (%s) with active children\n",
1298              dev_name(dev));
1299
1300         spin_unlock_irqrestore(&dev->power.lock, flags);
1301 }
1302 EXPORT_SYMBOL_GPL(pm_runtime_enable);
1303
1304 /**
1305  * pm_runtime_forbid - Block runtime PM of a device.
1306  * @dev: Device to handle.
1307  *
1308  * Increase the device's usage count and clear its power.runtime_auto flag,
1309  * so that it cannot be suspended at run time until pm_runtime_allow() is called
1310  * for it.
1311  */
1312 void pm_runtime_forbid(struct device *dev)
1313 {
1314         spin_lock_irq(&dev->power.lock);
1315         if (!dev->power.runtime_auto)
1316                 goto out;
1317
1318         dev->power.runtime_auto = false;
1319         atomic_inc(&dev->power.usage_count);
1320         rpm_resume(dev, 0);
1321
1322  out:
1323         spin_unlock_irq(&dev->power.lock);
1324 }
1325 EXPORT_SYMBOL_GPL(pm_runtime_forbid);
1326
1327 /**
1328  * pm_runtime_allow - Unblock runtime PM of a device.
1329  * @dev: Device to handle.
1330  *
1331  * Decrease the device's usage count and set its power.runtime_auto flag.
1332  */
1333 void pm_runtime_allow(struct device *dev)
1334 {
1335         spin_lock_irq(&dev->power.lock);
1336         if (dev->power.runtime_auto)
1337                 goto out;
1338
1339         dev->power.runtime_auto = true;
1340         if (atomic_dec_and_test(&dev->power.usage_count))
1341                 rpm_idle(dev, RPM_AUTO | RPM_ASYNC);
1342
1343  out:
1344         spin_unlock_irq(&dev->power.lock);
1345 }
1346 EXPORT_SYMBOL_GPL(pm_runtime_allow);
1347
1348 /**
1349  * pm_runtime_no_callbacks - Ignore runtime PM callbacks for a device.
1350  * @dev: Device to handle.
1351  *
1352  * Set the power.no_callbacks flag, which tells the PM core that this
1353  * device is power-managed through its parent and has no runtime PM
1354  * callbacks of its own.  The runtime sysfs attributes will be removed.
1355  */
1356 void pm_runtime_no_callbacks(struct device *dev)
1357 {
1358         spin_lock_irq(&dev->power.lock);
1359         dev->power.no_callbacks = 1;
1360         spin_unlock_irq(&dev->power.lock);
1361         if (device_is_registered(dev))
1362                 rpm_sysfs_remove(dev);
1363 }
1364 EXPORT_SYMBOL_GPL(pm_runtime_no_callbacks);
1365
1366 /**
1367  * pm_runtime_irq_safe - Leave interrupts disabled during callbacks.
1368  * @dev: Device to handle
1369  *
1370  * Set the power.irq_safe flag, which tells the PM core that the
1371  * ->runtime_suspend() and ->runtime_resume() callbacks for this device should
1372  * always be invoked with the spinlock held and interrupts disabled.  It also
1373  * causes the parent's usage counter to be permanently incremented, preventing
1374  * the parent from runtime suspending -- otherwise an irq-safe child might have
1375  * to wait for a non-irq-safe parent.
1376  */
1377 void pm_runtime_irq_safe(struct device *dev)
1378 {
1379         if (dev->parent)
1380                 pm_runtime_get_sync(dev->parent);
1381         spin_lock_irq(&dev->power.lock);
1382         dev->power.irq_safe = 1;
1383         spin_unlock_irq(&dev->power.lock);
1384 }
1385 EXPORT_SYMBOL_GPL(pm_runtime_irq_safe);
1386
1387 /**
1388  * update_autosuspend - Handle a change to a device's autosuspend settings.
1389  * @dev: Device to handle.
1390  * @old_delay: The former autosuspend_delay value.
1391  * @old_use: The former use_autosuspend value.
1392  *
1393  * Prevent runtime suspend if the new delay is negative and use_autosuspend is
1394  * set; otherwise allow it.  Send an idle notification if suspends are allowed.
1395  *
1396  * This function must be called under dev->power.lock with interrupts disabled.
1397  */
1398 static void update_autosuspend(struct device *dev, int old_delay, int old_use)
1399 {
1400         int delay = dev->power.autosuspend_delay;
1401
1402         /* Should runtime suspend be prevented now? */
1403         if (dev->power.use_autosuspend && delay < 0) {
1404
1405                 /* If it used to be allowed then prevent it. */
1406                 if (!old_use || old_delay >= 0) {
1407                         atomic_inc(&dev->power.usage_count);
1408                         rpm_resume(dev, 0);
1409                 }
1410         }
1411
1412         /* Runtime suspend should be allowed now. */
1413         else {
1414
1415                 /* If it used to be prevented then allow it. */
1416                 if (old_use && old_delay < 0)
1417                         atomic_dec(&dev->power.usage_count);
1418
1419                 /* Maybe we can autosuspend now. */
1420                 rpm_idle(dev, RPM_AUTO);
1421         }
1422 }
1423
1424 /**
1425  * pm_runtime_set_autosuspend_delay - Set a device's autosuspend_delay value.
1426  * @dev: Device to handle.
1427  * @delay: Value of the new delay in milliseconds.
1428  *
1429  * Set the device's power.autosuspend_delay value.  If it changes to negative
1430  * and the power.use_autosuspend flag is set, prevent runtime suspends.  If it
1431  * changes the other way, allow runtime suspends.
1432  */
1433 void pm_runtime_set_autosuspend_delay(struct device *dev, int delay)
1434 {
1435         int old_delay, old_use;
1436
1437         spin_lock_irq(&dev->power.lock);
1438         old_delay = dev->power.autosuspend_delay;
1439         old_use = dev->power.use_autosuspend;
1440         dev->power.autosuspend_delay = delay;
1441         update_autosuspend(dev, old_delay, old_use);
1442         spin_unlock_irq(&dev->power.lock);
1443 }
1444 EXPORT_SYMBOL_GPL(pm_runtime_set_autosuspend_delay);
1445
1446 /**
1447  * __pm_runtime_use_autosuspend - Set a device's use_autosuspend flag.
1448  * @dev: Device to handle.
1449  * @use: New value for use_autosuspend.
1450  *
1451  * Set the device's power.use_autosuspend flag, and allow or prevent runtime
1452  * suspends as needed.
1453  */
1454 void __pm_runtime_use_autosuspend(struct device *dev, bool use)
1455 {
1456         int old_delay, old_use;
1457
1458         spin_lock_irq(&dev->power.lock);
1459         old_delay = dev->power.autosuspend_delay;
1460         old_use = dev->power.use_autosuspend;
1461         dev->power.use_autosuspend = use;
1462         update_autosuspend(dev, old_delay, old_use);
1463         spin_unlock_irq(&dev->power.lock);
1464 }
1465 EXPORT_SYMBOL_GPL(__pm_runtime_use_autosuspend);
1466
1467 /**
1468  * pm_runtime_init - Initialize runtime PM fields in given device object.
1469  * @dev: Device object to initialize.
1470  */
1471 void pm_runtime_init(struct device *dev)
1472 {
1473         dev->power.runtime_status = RPM_SUSPENDED;
1474         dev->power.idle_notification = false;
1475
1476         dev->power.disable_depth = 1;
1477         atomic_set(&dev->power.usage_count, 0);
1478
1479         dev->power.runtime_error = 0;
1480
1481         atomic_set(&dev->power.child_count, 0);
1482         pm_suspend_ignore_children(dev, false);
1483         dev->power.runtime_auto = true;
1484
1485         dev->power.request_pending = false;
1486         dev->power.request = RPM_REQ_NONE;
1487         dev->power.deferred_resume = false;
1488         dev->power.accounting_timestamp = jiffies;
1489         INIT_WORK(&dev->power.work, pm_runtime_work);
1490
1491         dev->power.timer_expires = 0;
1492         timer_setup(&dev->power.suspend_timer, pm_suspend_timer_fn, 0);
1493
1494         init_waitqueue_head(&dev->power.wait_queue);
1495 }
1496
1497 /**
1498  * pm_runtime_reinit - Re-initialize runtime PM fields in given device object.
1499  * @dev: Device object to re-initialize.
1500  */
1501 void pm_runtime_reinit(struct device *dev)
1502 {
1503         if (!pm_runtime_enabled(dev)) {
1504                 if (dev->power.runtime_status == RPM_ACTIVE)
1505                         pm_runtime_set_suspended(dev);
1506                 if (dev->power.irq_safe) {
1507                         spin_lock_irq(&dev->power.lock);
1508                         dev->power.irq_safe = 0;
1509                         spin_unlock_irq(&dev->power.lock);
1510                         if (dev->parent)
1511                                 pm_runtime_put(dev->parent);
1512                 }
1513         }
1514 }
1515
1516 /**
1517  * pm_runtime_remove - Prepare for removing a device from device hierarchy.
1518  * @dev: Device object being removed from device hierarchy.
1519  */
1520 void pm_runtime_remove(struct device *dev)
1521 {
1522         __pm_runtime_disable(dev, false);
1523         pm_runtime_reinit(dev);
1524 }
1525
1526 /**
1527  * pm_runtime_clean_up_links - Prepare links to consumers for driver removal.
1528  * @dev: Device whose driver is going to be removed.
1529  *
1530  * Check links from this device to any consumers and if any of them have active
1531  * runtime PM references to the device, drop the usage counter of the device
1532  * (as many times as needed).
1533  *
1534  * Links with the DL_FLAG_MANAGED flag unset are ignored.
1535  *
1536  * Since the device is guaranteed to be runtime-active at the point this is
1537  * called, nothing else needs to be done here.
1538  *
1539  * Moreover, this is called after device_links_busy() has returned 'false', so
1540  * the status of each link is guaranteed to be DL_STATE_SUPPLIER_UNBIND and
1541  * therefore rpm_active can't be manipulated concurrently.
1542  */
1543 void pm_runtime_clean_up_links(struct device *dev)
1544 {
1545         struct device_link *link;
1546         int idx;
1547
1548         idx = device_links_read_lock();
1549
1550         list_for_each_entry_rcu(link, &dev->links.consumers, s_node) {
1551                 if (!(link->flags & DL_FLAG_MANAGED))
1552                         continue;
1553
1554                 while (refcount_dec_not_one(&link->rpm_active))
1555                         pm_runtime_put_noidle(dev);
1556         }
1557
1558         device_links_read_unlock(idx);
1559 }
1560
1561 /**
1562  * pm_runtime_get_suppliers - Resume and reference-count supplier devices.
1563  * @dev: Consumer device.
1564  */
1565 void pm_runtime_get_suppliers(struct device *dev)
1566 {
1567         struct device_link *link;
1568         int idx;
1569
1570         idx = device_links_read_lock();
1571
1572         list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
1573                 if (link->flags & DL_FLAG_PM_RUNTIME) {
1574                         link->supplier_preactivated = true;
1575                         pm_runtime_get_sync(link->supplier);
1576                         refcount_inc(&link->rpm_active);
1577                 }
1578
1579         device_links_read_unlock(idx);
1580 }
1581
1582 /**
1583  * pm_runtime_put_suppliers - Drop references to supplier devices.
1584  * @dev: Consumer device.
1585  */
1586 void pm_runtime_put_suppliers(struct device *dev)
1587 {
1588         struct device_link *link;
1589         unsigned long flags;
1590         bool put;
1591         int idx;
1592
1593         idx = device_links_read_lock();
1594
1595         list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
1596                 if (link->supplier_preactivated) {
1597                         link->supplier_preactivated = false;
1598                         spin_lock_irqsave(&dev->power.lock, flags);
1599                         put = pm_runtime_status_suspended(dev) &&
1600                               refcount_dec_not_one(&link->rpm_active);
1601                         spin_unlock_irqrestore(&dev->power.lock, flags);
1602                         if (put)
1603                                 pm_runtime_put(link->supplier);
1604                 }
1605
1606         device_links_read_unlock(idx);
1607 }
1608
1609 void pm_runtime_new_link(struct device *dev)
1610 {
1611         spin_lock_irq(&dev->power.lock);
1612         dev->power.links_count++;
1613         spin_unlock_irq(&dev->power.lock);
1614 }
1615
1616 void pm_runtime_drop_link(struct device *dev)
1617 {
1618         spin_lock_irq(&dev->power.lock);
1619         WARN_ON(dev->power.links_count == 0);
1620         dev->power.links_count--;
1621         spin_unlock_irq(&dev->power.lock);
1622 }
1623
1624 static bool pm_runtime_need_not_resume(struct device *dev)
1625 {
1626         return atomic_read(&dev->power.usage_count) <= 1 &&
1627                 (atomic_read(&dev->power.child_count) == 0 ||
1628                  dev->power.ignore_children);
1629 }
1630
1631 /**
1632  * pm_runtime_force_suspend - Force a device into suspend state if needed.
1633  * @dev: Device to suspend.
1634  *
1635  * Disable runtime PM so we safely can check the device's runtime PM status and
1636  * if it is active, invoke its ->runtime_suspend callback to suspend it and
1637  * change its runtime PM status field to RPM_SUSPENDED.  Also, if the device's
1638  * usage and children counters don't indicate that the device was in use before
1639  * the system-wide transition under way, decrement its parent's children counter
1640  * (if there is a parent).  Keep runtime PM disabled to preserve the state
1641  * unless we encounter errors.
1642  *
1643  * Typically this function may be invoked from a system suspend callback to make
1644  * sure the device is put into low power state and it should only be used during
1645  * system-wide PM transitions to sleep states.  It assumes that the analogous
1646  * pm_runtime_force_resume() will be used to resume the device.
1647  */
1648 int pm_runtime_force_suspend(struct device *dev)
1649 {
1650         int (*callback)(struct device *);
1651         int ret;
1652
1653         pm_runtime_disable(dev);
1654         if (pm_runtime_status_suspended(dev))
1655                 return 0;
1656
1657         callback = RPM_GET_CALLBACK(dev, runtime_suspend);
1658
1659         ret = callback ? callback(dev) : 0;
1660         if (ret)
1661                 goto err;
1662
1663         /*
1664          * If the device can stay in suspend after the system-wide transition
1665          * to the working state that will follow, drop the children counter of
1666          * its parent, but set its status to RPM_SUSPENDED anyway in case this
1667          * function will be called again for it in the meantime.
1668          */
1669         if (pm_runtime_need_not_resume(dev))
1670                 pm_runtime_set_suspended(dev);
1671         else
1672                 __update_runtime_status(dev, RPM_SUSPENDED);
1673
1674         return 0;
1675
1676 err:
1677         pm_runtime_enable(dev);
1678         return ret;
1679 }
1680 EXPORT_SYMBOL_GPL(pm_runtime_force_suspend);
1681
1682 /**
1683  * pm_runtime_force_resume - Force a device into resume state if needed.
1684  * @dev: Device to resume.
1685  *
1686  * Prior invoking this function we expect the user to have brought the device
1687  * into low power state by a call to pm_runtime_force_suspend(). Here we reverse
1688  * those actions and bring the device into full power, if it is expected to be
1689  * used on system resume.  In the other case, we defer the resume to be managed
1690  * via runtime PM.
1691  *
1692  * Typically this function may be invoked from a system resume callback.
1693  */
1694 int pm_runtime_force_resume(struct device *dev)
1695 {
1696         int (*callback)(struct device *);
1697         int ret = 0;
1698
1699         if (!pm_runtime_status_suspended(dev) || pm_runtime_need_not_resume(dev))
1700                 goto out;
1701
1702         /*
1703          * The value of the parent's children counter is correct already, so
1704          * just update the status of the device.
1705          */
1706         __update_runtime_status(dev, RPM_ACTIVE);
1707
1708         callback = RPM_GET_CALLBACK(dev, runtime_resume);
1709
1710         ret = callback ? callback(dev) : 0;
1711         if (ret) {
1712                 pm_runtime_set_suspended(dev);
1713                 goto out;
1714         }
1715
1716         pm_runtime_mark_last_busy(dev);
1717 out:
1718         pm_runtime_enable(dev);
1719         return ret;
1720 }
1721 EXPORT_SYMBOL_GPL(pm_runtime_force_resume);