drivers/base/power/runtime.c

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