1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * drivers/base/power/runtime.c - Helper functions for device runtime PM
   4 *
   5 * Copyright (c) 2009 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
   6 * Copyright (C) 2010 Alan Stern <stern@rowland.harvard.edu>
   7 */
   8#include <linux/sched/mm.h>
   9#include <linux/ktime.h>
  10#include <linux/hrtimer.h>
  11#include <linux/export.h>
  12#include <linux/pm_runtime.h>
  13#include <linux/pm_wakeirq.h>
  14#include <trace/events/rpm.h>
  15
  16#include "../base.h"
  17#include "power.h"
  18
  19typedef int (*pm_callback_t)(struct device *);
  20
  21static pm_callback_t __rpm_get_callback(struct device *dev, size_t cb_offset)
  22{
  23	pm_callback_t cb;
  24	const struct dev_pm_ops *ops;
  25
  26	if (dev->pm_domain)
  27		ops = &dev->pm_domain->ops;
  28	else if (dev->type && dev->type->pm)
  29		ops = dev->type->pm;
  30	else if (dev->class && dev->class->pm)
  31		ops = dev->class->pm;
  32	else if (dev->bus && dev->bus->pm)
  33		ops = dev->bus->pm;
  34	else
  35		ops = NULL;
  36
  37	if (ops)
  38		cb = *(pm_callback_t *)((void *)ops + cb_offset);
  39	else
  40		cb = NULL;
  41
  42	if (!cb && dev->driver && dev->driver->pm)
  43		cb = *(pm_callback_t *)((void *)dev->driver->pm + cb_offset);
  44
  45	return cb;
  46}
  47
  48#define RPM_GET_CALLBACK(dev, callback) \
  49		__rpm_get_callback(dev, offsetof(struct dev_pm_ops, callback))
  50
  51static int rpm_resume(struct device *dev, int rpmflags);
  52static int rpm_suspend(struct device *dev, int rpmflags);
  53
  54/**
  55 * update_pm_runtime_accounting - Update the time accounting of power states
  56 * @dev: Device to update the accounting for
  57 *
  58 * In order to be able to have time accounting of the various power states
  59 * (as used by programs such as PowerTOP to show the effectiveness of runtime
  60 * PM), we need to track the time spent in each state.
  61 * update_pm_runtime_accounting must be called each time before the
  62 * runtime_status field is updated, to account the time in the old state
  63 * correctly.
  64 */
  65static void update_pm_runtime_accounting(struct device *dev)
  66{
  67	u64 now, last, delta;
  68
  69	if (dev->power.disable_depth > 0)
  70		return;
  71
  72	last = dev->power.accounting_timestamp;
  73
  74	now = ktime_get_mono_fast_ns();
  75	dev->power.accounting_timestamp = now;
  76
  77	/*
  78	 * Because ktime_get_mono_fast_ns() is not monotonic during
  79	 * timekeeping updates, ensure that 'now' is after the last saved
  80	 * timesptamp.
  81	 */
  82	if (now < last)
  83		return;
  84
  85	delta = now - last;
  86
  87	if (dev->power.runtime_status == RPM_SUSPENDED)
  88		dev->power.suspended_time += delta;
  89	else
  90		dev->power.active_time += delta;
  91}
  92
  93static void __update_runtime_status(struct device *dev, enum rpm_status status)
  94{
  95	update_pm_runtime_accounting(dev);
  96	dev->power.runtime_status = status;
  97}
  98
  99static u64 rpm_get_accounted_time(struct device *dev, bool suspended)
 100{
 101	u64 time;
 102	unsigned long flags;
 103
 104	spin_lock_irqsave(&dev->power.lock, flags);
 105
 106	update_pm_runtime_accounting(dev);
 107	time = suspended ? dev->power.suspended_time : dev->power.active_time;
 108
 109	spin_unlock_irqrestore(&dev->power.lock, flags);
 110
 111	return time;
 112}
 113
 114u64 pm_runtime_active_time(struct device *dev)
 115{
 116	return rpm_get_accounted_time(dev, false);
 117}
 118
 119u64 pm_runtime_suspended_time(struct device *dev)
 120{
 121	return rpm_get_accounted_time(dev, true);
 122}
 123EXPORT_SYMBOL_GPL(pm_runtime_suspended_time);
 124
 125/**
 126 * pm_runtime_deactivate_timer - Deactivate given device's suspend timer.
 127 * @dev: Device to handle.
 128 */
 129static void pm_runtime_deactivate_timer(struct device *dev)
 130{
 131	if (dev->power.timer_expires > 0) {
 132		hrtimer_try_to_cancel(&dev->power.suspend_timer);
 133		dev->power.timer_expires = 0;
 134	}
 135}
 136
 137/**
 138 * pm_runtime_cancel_pending - Deactivate suspend timer and cancel requests.
 139 * @dev: Device to handle.
 140 */
 141static void pm_runtime_cancel_pending(struct device *dev)
 142{
 143	pm_runtime_deactivate_timer(dev);
 144	/*
 145	 * In case there's a request pending, make sure its work function will
 146	 * return without doing anything.
 147	 */
 148	dev->power.request = RPM_REQ_NONE;
 149}
 150
 151/*
 152 * pm_runtime_autosuspend_expiration - Get a device's autosuspend-delay expiration time.
 153 * @dev: Device to handle.
 154 *
 155 * Compute the autosuspend-delay expiration time based on the device's
 156 * power.last_busy time.  If the delay has already expired or is disabled
 157 * (negative) or the power.use_autosuspend flag isn't set, return 0.
 158 * Otherwise return the expiration time in nanoseconds (adjusted to be nonzero).
 159 *
 160 * This function may be called either with or without dev->power.lock held.
 161 * Either way it can be racy, since power.last_busy may be updated at any time.
 162 */
 163u64 pm_runtime_autosuspend_expiration(struct device *dev)
 164{
 165	int autosuspend_delay;
 166	u64 expires;
 167
 168	if (!dev->power.use_autosuspend)
 169		return 0;
 170
 171	autosuspend_delay = READ_ONCE(dev->power.autosuspend_delay);
 172	if (autosuspend_delay < 0)
 173		return 0;
 174
 175	expires  = READ_ONCE(dev->power.last_busy);
 176	expires += (u64)autosuspend_delay * NSEC_PER_MSEC;
 177	if (expires > ktime_get_mono_fast_ns())
 178		return expires;	/* Expires in the future */
 179
 180	return 0;
 181}
 182EXPORT_SYMBOL_GPL(pm_runtime_autosuspend_expiration);
 183
 184static int dev_memalloc_noio(struct device *dev, void *data)
 185{
 186	return dev->power.memalloc_noio;
 187}
 188
 189/*
 190 * pm_runtime_set_memalloc_noio - Set a device's memalloc_noio flag.
 191 * @dev: Device to handle.
 192 * @enable: True for setting the flag and False for clearing the flag.
 193 *
 194 * Set the flag for all devices in the path from the device to the
 195 * root device in the device tree if @enable is true, otherwise clear
 196 * the flag for devices in the path whose siblings don't set the flag.
 197 *
 198 * The function should only be called by block device, or network
 199 * device driver for solving the deadlock problem during runtime
 200 * resume/suspend:
 201 *
 202 *     If memory allocation with GFP_KERNEL is called inside runtime
 203 *     resume/suspend callback of any one of its ancestors(or the
 204 *     block device itself), the deadlock may be triggered inside the
 205 *     memory allocation since it might not complete until the block
 206 *     device becomes active and the involed page I/O finishes. The
 207 *     situation is pointed out first by Alan Stern. Network device
 208 *     are involved in iSCSI kind of situation.
 209 *
 210 * The lock of dev_hotplug_mutex is held in the function for handling
 211 * hotplug race because pm_runtime_set_memalloc_noio() may be called
 212 * in async probe().
 213 *
 214 * The function should be called between device_add() and device_del()
 215 * on the affected device(block/network device).
 216 */
 217void pm_runtime_set_memalloc_noio(struct device *dev, bool enable)
 218{
 219	static DEFINE_MUTEX(dev_hotplug_mutex);
 220
 221	mutex_lock(&dev_hotplug_mutex);
 222	for (;;) {
 223		bool enabled;
 224
 225		/* hold power lock since bitfield is not SMP-safe. */
 226		spin_lock_irq(&dev->power.lock);
 227		enabled = dev->power.memalloc_noio;
 228		dev->power.memalloc_noio = enable;
 229		spin_unlock_irq(&dev->power.lock);
 230
 231		/*
 232		 * not need to enable ancestors any more if the device
 233		 * has been enabled.
 234		 */
 235		if (enabled && enable)
 236			break;
 237
 238		dev = dev->parent;
 239
 240		/*
 241		 * clear flag of the parent device only if all the
 242		 * children don't set the flag because ancestor's
 243		 * flag was set by any one of the descendants.
 244		 */
 245		if (!dev || (!enable &&
 246			     device_for_each_child(dev, NULL,
 247						   dev_memalloc_noio)))
 248			break;
 249	}
 250	mutex_unlock(&dev_hotplug_mutex);
 251}
 252EXPORT_SYMBOL_GPL(pm_runtime_set_memalloc_noio);
 253
 254/**
 255 * rpm_check_suspend_allowed - Test whether a device may be suspended.
 256 * @dev: Device to test.
 257 */
 258static int rpm_check_suspend_allowed(struct device *dev)
 259{
 260	int retval = 0;
 261
 262	if (dev->power.runtime_error)
 263		retval = -EINVAL;
 264	else if (dev->power.disable_depth > 0)
 265		retval = -EACCES;
 266	else if (atomic_read(&dev->power.usage_count) > 0)
 267		retval = -EAGAIN;
 268	else if (!dev->power.ignore_children &&
 269			atomic_read(&dev->power.child_count))
 270		retval = -EBUSY;
 271
 272	/* Pending resume requests take precedence over suspends. */
 273	else if ((dev->power.deferred_resume
 274			&& dev->power.runtime_status == RPM_SUSPENDING)
 275	    || (dev->power.request_pending
 276			&& dev->power.request == RPM_REQ_RESUME))
 277		retval = -EAGAIN;
 278	else if (__dev_pm_qos_resume_latency(dev) == 0)
 279		retval = -EPERM;
 280	else if (dev->power.runtime_status == RPM_SUSPENDED)
 281		retval = 1;
 282
 283	return retval;
 284}
 285
 286static int rpm_get_suppliers(struct device *dev)
 287{
 288	struct device_link *link;
 289
 290	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
 291				device_links_read_lock_held()) {
 292		int retval;
 293
 294		if (!(link->flags & DL_FLAG_PM_RUNTIME) ||
 295		    READ_ONCE(link->status) == DL_STATE_SUPPLIER_UNBIND)
 296			continue;
 297
 298		retval = pm_runtime_get_sync(link->supplier);
 299		/* Ignore suppliers with disabled runtime PM. */
 300		if (retval < 0 && retval != -EACCES) {
 301			pm_runtime_put_noidle(link->supplier);
 302			return retval;
 303		}
 304		refcount_inc(&link->rpm_active);
 305	}
 306	return 0;
 307}
 308
 309static void rpm_put_suppliers(struct device *dev)
 310{
 311	struct device_link *link;
 312
 313	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
 314				device_links_read_lock_held()) {
 315		if (READ_ONCE(link->status) == DL_STATE_SUPPLIER_UNBIND)
 316			continue;
 317
 318		while (refcount_dec_not_one(&link->rpm_active))
 319			pm_runtime_put(link->supplier);
 320	}
 321}
 322
 323/**
 324 * __rpm_callback - Run a given runtime PM callback for a given device.
 325 * @cb: Runtime PM callback to run.
 326 * @dev: Device to run the callback for.
 327 */
 328static int __rpm_callback(int (*cb)(struct device *), struct device *dev)
 329	__releases(&dev->power.lock) __acquires(&dev->power.lock)
 330{
 331	int retval, idx;
 332	bool use_links = dev->power.links_count > 0;
 333
 334	if (dev->power.irq_safe) {
 335		spin_unlock(&dev->power.lock);
 336	} else {
 337		spin_unlock_irq(&dev->power.lock);
 338
 339		/*
 340		 * Resume suppliers if necessary.
 341		 *
 342		 * The device's runtime PM status cannot change until this
 343		 * routine returns, so it is safe to read the status outside of
 344		 * the lock.
 345		 */
 346		if (use_links && dev->power.runtime_status == RPM_RESUMING) {
 347			idx = device_links_read_lock();
 348
 349			retval = rpm_get_suppliers(dev);
 350			if (retval)
 351				goto fail;
 352
 353			device_links_read_unlock(idx);
 354		}
 355	}
 356
 357	retval = cb(dev);
 358
 359	if (dev->power.irq_safe) {
 360		spin_lock(&dev->power.lock);
 361	} else {
 362		/*
 363		 * If the device is suspending and the callback has returned
 364		 * success, drop the usage counters of the suppliers that have
 365		 * been reference counted on its resume.
 366		 *
 367		 * Do that if resume fails too.
 368		 */
 369		if (use_links
 370		    && ((dev->power.runtime_status == RPM_SUSPENDING && !retval)
 371		    || (dev->power.runtime_status == RPM_RESUMING && retval))) {
 372			idx = device_links_read_lock();
 373
 374 fail:
 375			rpm_put_suppliers(dev);
 376
 377			device_links_read_unlock(idx);
 378		}
 379
 380		spin_lock_irq(&dev->power.lock);
 381	}
 382
 383	return retval;
 384}
 385
 386/**
 387 * rpm_idle - Notify device bus type if the device can be suspended.
 388 * @dev: Device to notify the bus type about.
 389 * @rpmflags: Flag bits.
 390 *
 391 * Check if the device's runtime PM status allows it to be suspended.  If
 392 * another idle notification has been started earlier, return immediately.  If
 393 * the RPM_ASYNC flag is set then queue an idle-notification request; otherwise
 394 * run the ->runtime_idle() callback directly. If the ->runtime_idle callback
 395 * doesn't exist or if it returns 0, call rpm_suspend with the RPM_AUTO flag.
 396 *
 397 * This function must be called under dev->power.lock with interrupts disabled.
 398 */
 399static int rpm_idle(struct device *dev, int rpmflags)
 400{
 401	int (*callback)(struct device *);
 402	int retval;
 403
 404	trace_rpm_idle_rcuidle(dev, rpmflags);
 405	retval = rpm_check_suspend_allowed(dev);
 406	if (retval < 0)
 407		;	/* Conditions are wrong. */
 408
 409	/* Idle notifications are allowed only in the RPM_ACTIVE state. */
 410	else if (dev->power.runtime_status != RPM_ACTIVE)
 411		retval = -EAGAIN;
 412
 413	/*
 414	 * Any pending request other than an idle notification takes
 415	 * precedence over us, except that the timer may be running.
 416	 */
 417	else if (dev->power.request_pending &&
 418	    dev->power.request > RPM_REQ_IDLE)
 419		retval = -EAGAIN;
 420
 421	/* Act as though RPM_NOWAIT is always set. */
 422	else if (dev->power.idle_notification)
 423		retval = -EINPROGRESS;
 424	if (retval)
 425		goto out;
 426
 427	/* Pending requests need to be canceled. */
 428	dev->power.request = RPM_REQ_NONE;
 429
 430	if (dev->power.no_callbacks)
 431		goto out;
 432
 433	/* Carry out an asynchronous or a synchronous idle notification. */
 434	if (rpmflags & RPM_ASYNC) {
 435		dev->power.request = RPM_REQ_IDLE;
 436		if (!dev->power.request_pending) {
 437			dev->power.request_pending = true;
 438			queue_work(pm_wq, &dev->power.work);
 439		}
 440		trace_rpm_return_int_rcuidle(dev, _THIS_IP_, 0);
 441		return 0;
 442	}
 443
 444	dev->power.idle_notification = true;
 445
 446	callback = RPM_GET_CALLBACK(dev, runtime_idle);
 447
 448	if (callback)
 449		retval = __rpm_callback(callback, dev);
 450
 451	dev->power.idle_notification = false;
 452	wake_up_all(&dev->power.wait_queue);
 453
 454 out:
 455	trace_rpm_return_int_rcuidle(dev, _THIS_IP_, retval);
 456	return retval ? retval : rpm_suspend(dev, rpmflags | RPM_AUTO);
 457}
 458
 459/**
 460 * rpm_callback - Run a given runtime PM callback for a given device.
 461 * @cb: Runtime PM callback to run.
 462 * @dev: Device to run the callback for.
 463 */
 464static int rpm_callback(int (*cb)(struct device *), struct device *dev)
 465{
 466	int retval;
 467
 468	if (!cb)
 469		return -ENOSYS;
 470
 471	if (dev->power.memalloc_noio) {
 472		unsigned int noio_flag;
 473
 474		/*
 475		 * Deadlock might be caused if memory allocation with
 476		 * GFP_KERNEL happens inside runtime_suspend and
 477		 * runtime_resume callbacks of one block device's
 478		 * ancestor or the block device itself. Network
 479		 * device might be thought as part of iSCSI block
 480		 * device, so network device and its ancestor should
 481		 * be marked as memalloc_noio too.
 482		 */
 483		noio_flag = memalloc_noio_save();
 484		retval = __rpm_callback(cb, dev);
 485		memalloc_noio_restore(noio_flag);
 486	} else {
 487		retval = __rpm_callback(cb, dev);
 488	}
 489
 490	dev->power.runtime_error = retval;
 491	return retval != -EACCES ? retval : -EIO;
 492}
 493
 494/**
 495 * rpm_suspend - Carry out runtime suspend of given device.
 496 * @dev: Device to suspend.
 497 * @rpmflags: Flag bits.
 498 *
 499 * Check if the device's runtime PM status allows it to be suspended.
 500 * Cancel a pending idle notification, autosuspend or suspend. If
 501 * another suspend has been started earlier, either return immediately
 502 * or wait for it to finish, depending on the RPM_NOWAIT and RPM_ASYNC
 503 * flags. If the RPM_ASYNC flag is set then queue a suspend request;
 504 * otherwise run the ->runtime_suspend() callback directly. When
 505 * ->runtime_suspend succeeded, if a deferred resume was requested while
 506 * the callback was running then carry it out, otherwise send an idle
 507 * notification for its parent (if the suspend succeeded and both
 508 * ignore_children of parent->power and irq_safe of dev->power are not set).
 509 * If ->runtime_suspend failed with -EAGAIN or -EBUSY, and if the RPM_AUTO
 510 * flag is set and the next autosuspend-delay expiration time is in the
 511 * future, schedule another autosuspend attempt.
 512 *
 513 * This function must be called under dev->power.lock with interrupts disabled.
 514 */
 515static int rpm_suspend(struct device *dev, int rpmflags)
 516	__releases(&dev->power.lock) __acquires(&dev->power.lock)
 517{
 518	int (*callback)(struct device *);
 519	struct device *parent = NULL;
 520	int retval;
 521
 522	trace_rpm_suspend_rcuidle(dev, rpmflags);
 523
 524 repeat:
 525	retval = rpm_check_suspend_allowed(dev);
 
 526	if (retval < 0)
 527		goto out;	/* Conditions are wrong. */
 528
 529	/* Synchronous suspends are not allowed in the RPM_RESUMING state. */
 530	if (dev->power.runtime_status == RPM_RESUMING && !(rpmflags & RPM_ASYNC))
 
 531		retval = -EAGAIN;
 532	if (retval)
 533		goto out;
 534
 535	/* If the autosuspend_delay time hasn't expired yet, reschedule. */
 536	if ((rpmflags & RPM_AUTO)
 537	    && dev->power.runtime_status != RPM_SUSPENDING) {
 538		u64 expires = pm_runtime_autosuspend_expiration(dev);
 539
 540		if (expires != 0) {
 541			/* Pending requests need to be canceled. */
 542			dev->power.request = RPM_REQ_NONE;
 543
 544			/*
 545			 * Optimization: If the timer is already running and is
 546			 * set to expire at or before the autosuspend delay,
 547			 * avoid the overhead of resetting it.  Just let it
 548			 * expire; pm_suspend_timer_fn() will take care of the
 549			 * rest.
 550			 */
 551			if (!(dev->power.timer_expires &&
 552					dev->power.timer_expires <= expires)) {
 553				/*
 554				 * We add a slack of 25% to gather wakeups
 555				 * without sacrificing the granularity.
 556				 */
 557				u64 slack = (u64)READ_ONCE(dev->power.autosuspend_delay) *
 558						    (NSEC_PER_MSEC >> 2);
 559
 560				dev->power.timer_expires = expires;
 561				hrtimer_start_range_ns(&dev->power.suspend_timer,
 562						ns_to_ktime(expires),
 563						slack,
 564						HRTIMER_MODE_ABS);
 565			}
 566			dev->power.timer_autosuspends = 1;
 567			goto out;
 568		}
 569	}
 570
 571	/* Other scheduled or pending requests need to be canceled. */
 572	pm_runtime_cancel_pending(dev);
 573
 574	if (dev->power.runtime_status == RPM_SUSPENDING) {
 575		DEFINE_WAIT(wait);
 576
 577		if (rpmflags & (RPM_ASYNC | RPM_NOWAIT)) {
 578			retval = -EINPROGRESS;
 579			goto out;
 580		}
 581
 582		if (dev->power.irq_safe) {
 583			spin_unlock(&dev->power.lock);
 584
 585			cpu_relax();
 586
 587			spin_lock(&dev->power.lock);
 588			goto repeat;
 589		}
 590
 591		/* Wait for the other suspend running in parallel with us. */
 592		for (;;) {
 593			prepare_to_wait(&dev->power.wait_queue, &wait,
 594					TASK_UNINTERRUPTIBLE);
 595			if (dev->power.runtime_status != RPM_SUSPENDING)
 596				break;
 597
 598			spin_unlock_irq(&dev->power.lock);
 599
 600			schedule();
 601
 602			spin_lock_irq(&dev->power.lock);
 603		}
 604		finish_wait(&dev->power.wait_queue, &wait);
 605		goto repeat;
 606	}
 607
 608	if (dev->power.no_callbacks)
 609		goto no_callback;	/* Assume success. */
 610
 611	/* Carry out an asynchronous or a synchronous suspend. */
 612	if (rpmflags & RPM_ASYNC) {
 613		dev->power.request = (rpmflags & RPM_AUTO) ?
 614		    RPM_REQ_AUTOSUSPEND : RPM_REQ_SUSPEND;
 615		if (!dev->power.request_pending) {
 616			dev->power.request_pending = true;
 617			queue_work(pm_wq, &dev->power.work);
 618		}
 619		goto out;
 620	}
 621
 622	__update_runtime_status(dev, RPM_SUSPENDING);
 623
 624	callback = RPM_GET_CALLBACK(dev, runtime_suspend);
 625
 626	dev_pm_enable_wake_irq_check(dev, true);
 627	retval = rpm_callback(callback, dev);
 628	if (retval)
 629		goto fail;
 630
 631 no_callback:
 632	__update_runtime_status(dev, RPM_SUSPENDED);
 633	pm_runtime_deactivate_timer(dev);
 634
 635	if (dev->parent) {
 636		parent = dev->parent;
 637		atomic_add_unless(&parent->power.child_count, -1, 0);
 638	}
 639	wake_up_all(&dev->power.wait_queue);
 640
 641	if (dev->power.deferred_resume) {
 642		dev->power.deferred_resume = false;
 643		rpm_resume(dev, 0);
 644		retval = -EAGAIN;
 645		goto out;
 646	}
 647
 648	/* Maybe the parent is now able to suspend. */
 649	if (parent && !parent->power.ignore_children && !dev->power.irq_safe) {
 650		spin_unlock(&dev->power.lock);
 651
 652		spin_lock(&parent->power.lock);
 653		rpm_idle(parent, RPM_ASYNC);
 654		spin_unlock(&parent->power.lock);
 655
 656		spin_lock(&dev->power.lock);
 657	}
 658
 659 out:
 660	trace_rpm_return_int_rcuidle(dev, _THIS_IP_, retval);
 661
 662	return retval;
 663
 664 fail:
 665	dev_pm_disable_wake_irq_check(dev);
 666	__update_runtime_status(dev, RPM_ACTIVE);
 667	dev->power.deferred_resume = false;
 668	wake_up_all(&dev->power.wait_queue);
 669
 670	if (retval == -EAGAIN || retval == -EBUSY) {
 671		dev->power.runtime_error = 0;
 672
 673		/*
 674		 * If the callback routine failed an autosuspend, and
 675		 * if the last_busy time has been updated so that there
 676		 * is a new autosuspend expiration time, automatically
 677		 * reschedule another autosuspend.
 678		 */
 679		if ((rpmflags & RPM_AUTO) &&
 680		    pm_runtime_autosuspend_expiration(dev) != 0)
 681			goto repeat;
 682	} else {
 683		pm_runtime_cancel_pending(dev);
 684	}
 685	goto out;
 686}
 687
 688/**
 689 * rpm_resume - Carry out runtime resume of given device.
 690 * @dev: Device to resume.
 691 * @rpmflags: Flag bits.
 692 *
 693 * Check if the device's runtime PM status allows it to be resumed.  Cancel
 694 * any scheduled or pending requests.  If another resume has been started
 695 * earlier, either return immediately or wait for it to finish, depending on the
 696 * RPM_NOWAIT and RPM_ASYNC flags.  Similarly, if there's a suspend running in
 697 * parallel with this function, either tell the other process to resume after
 698 * suspending (deferred_resume) or wait for it to finish.  If the RPM_ASYNC
 699 * flag is set then queue a resume request; otherwise run the
 700 * ->runtime_resume() callback directly.  Queue an idle notification for the
 701 * device if the resume succeeded.
 702 *
 703 * This function must be called under dev->power.lock with interrupts disabled.
 704 */
 705static int rpm_resume(struct device *dev, int rpmflags)
 706	__releases(&dev->power.lock) __acquires(&dev->power.lock)
 707{
 708	int (*callback)(struct device *);
 709	struct device *parent = NULL;
 710	int retval = 0;
 711
 712	trace_rpm_resume_rcuidle(dev, rpmflags);
 713
 714 repeat:
 715	if (dev->power.runtime_error)
 716		retval = -EINVAL;
 717	else if (dev->power.disable_depth == 1 && dev->power.is_suspended
 718	    && dev->power.runtime_status == RPM_ACTIVE)
 719		retval = 1;
 720	else if (dev->power.disable_depth > 0)
 721		retval = -EACCES;
 722	if (retval)
 723		goto out;
 724
 725	/*
 726	 * Other scheduled or pending requests need to be canceled.  Small
 727	 * optimization: If an autosuspend timer is running, leave it running
 728	 * rather than cancelling it now only to restart it again in the near
 729	 * future.
 730	 */
 731	dev->power.request = RPM_REQ_NONE;
 732	if (!dev->power.timer_autosuspends)
 733		pm_runtime_deactivate_timer(dev);
 734
 735	if (dev->power.runtime_status == RPM_ACTIVE) {
 736		retval = 1;
 737		goto out;
 738	}
 739
 740	if (dev->power.runtime_status == RPM_RESUMING
 741	    || dev->power.runtime_status == RPM_SUSPENDING) {
 742		DEFINE_WAIT(wait);
 743
 744		if (rpmflags & (RPM_ASYNC | RPM_NOWAIT)) {
 745			if (dev->power.runtime_status == RPM_SUSPENDING)
 746				dev->power.deferred_resume = true;
 747			else
 748				retval = -EINPROGRESS;
 749			goto out;
 750		}
 751
 752		if (dev->power.irq_safe) {
 753			spin_unlock(&dev->power.lock);
 754
 755			cpu_relax();
 756
 757			spin_lock(&dev->power.lock);
 758			goto repeat;
 759		}
 760
 761		/* Wait for the operation carried out in parallel with us. */
 762		for (;;) {
 763			prepare_to_wait(&dev->power.wait_queue, &wait,
 764					TASK_UNINTERRUPTIBLE);
 765			if (dev->power.runtime_status != RPM_RESUMING
 766			    && dev->power.runtime_status != RPM_SUSPENDING)
 767				break;
 768
 769			spin_unlock_irq(&dev->power.lock);
 770
 771			schedule();
 772
 773			spin_lock_irq(&dev->power.lock);
 774		}
 775		finish_wait(&dev->power.wait_queue, &wait);
 776		goto repeat;
 777	}
 778
 779	/*
 780	 * See if we can skip waking up the parent.  This is safe only if
 781	 * power.no_callbacks is set, because otherwise we don't know whether
 782	 * the resume will actually succeed.
 783	 */
 784	if (dev->power.no_callbacks && !parent && dev->parent) {
 785		spin_lock_nested(&dev->parent->power.lock, SINGLE_DEPTH_NESTING);
 786		if (dev->parent->power.disable_depth > 0
 787		    || dev->parent->power.ignore_children
 788		    || dev->parent->power.runtime_status == RPM_ACTIVE) {
 789			atomic_inc(&dev->parent->power.child_count);
 790			spin_unlock(&dev->parent->power.lock);
 791			retval = 1;
 792			goto no_callback;	/* Assume success. */
 793		}
 794		spin_unlock(&dev->parent->power.lock);
 795	}
 796
 797	/* Carry out an asynchronous or a synchronous resume. */
 798	if (rpmflags & RPM_ASYNC) {
 799		dev->power.request = RPM_REQ_RESUME;
 800		if (!dev->power.request_pending) {
 801			dev->power.request_pending = true;
 802			queue_work(pm_wq, &dev->power.work);
 803		}
 804		retval = 0;
 805		goto out;
 806	}
 807
 808	if (!parent && dev->parent) {
 809		/*
 810		 * Increment the parent's usage counter and resume it if
 811		 * necessary.  Not needed if dev is irq-safe; then the
 812		 * parent is permanently resumed.
 813		 */
 814		parent = dev->parent;
 815		if (dev->power.irq_safe)
 816			goto skip_parent;
 817		spin_unlock(&dev->power.lock);
 818
 819		pm_runtime_get_noresume(parent);
 820
 821		spin_lock(&parent->power.lock);
 822		/*
 823		 * Resume the parent if it has runtime PM enabled and not been
 824		 * set to ignore its children.
 825		 */
 826		if (!parent->power.disable_depth
 827		    && !parent->power.ignore_children) {
 828			rpm_resume(parent, 0);
 829			if (parent->power.runtime_status != RPM_ACTIVE)
 830				retval = -EBUSY;
 831		}
 832		spin_unlock(&parent->power.lock);
 833
 834		spin_lock(&dev->power.lock);
 835		if (retval)
 836			goto out;
 837		goto repeat;
 838	}
 839 skip_parent:
 840
 841	if (dev->power.no_callbacks)
 842		goto no_callback;	/* Assume success. */
 843
 844	__update_runtime_status(dev, RPM_RESUMING);
 845
 846	callback = RPM_GET_CALLBACK(dev, runtime_resume);
 847
 848	dev_pm_disable_wake_irq_check(dev);
 849	retval = rpm_callback(callback, dev);
 850	if (retval) {
 851		__update_runtime_status(dev, RPM_SUSPENDED);
 852		pm_runtime_cancel_pending(dev);
 853		dev_pm_enable_wake_irq_check(dev, false);
 854	} else {
 855 no_callback:
 856		__update_runtime_status(dev, RPM_ACTIVE);
 857		pm_runtime_mark_last_busy(dev);
 858		if (parent)
 859			atomic_inc(&parent->power.child_count);
 860	}
 861	wake_up_all(&dev->power.wait_queue);
 862
 863	if (retval >= 0)
 864		rpm_idle(dev, RPM_ASYNC);
 865
 866 out:
 867	if (parent && !dev->power.irq_safe) {
 868		spin_unlock_irq(&dev->power.lock);
 869
 870		pm_runtime_put(parent);
 871
 872		spin_lock_irq(&dev->power.lock);
 873	}
 874
 875	trace_rpm_return_int_rcuidle(dev, _THIS_IP_, retval);
 876
 877	return retval;
 878}
 879
 880/**
 881 * pm_runtime_work - Universal runtime PM work function.
 882 * @work: Work structure used for scheduling the execution of this function.
 883 *
 884 * Use @work to get the device object the work is to be done for, determine what
 885 * is to be done and execute the appropriate runtime PM function.
 886 */
 887static void pm_runtime_work(struct work_struct *work)
 888{
 889	struct device *dev = container_of(work, struct device, power.work);
 890	enum rpm_request req;
 891
 892	spin_lock_irq(&dev->power.lock);
 893
 894	if (!dev->power.request_pending)
 895		goto out;
 896
 897	req = dev->power.request;
 898	dev->power.request = RPM_REQ_NONE;
 899	dev->power.request_pending = false;
 900
 901	switch (req) {
 902	case RPM_REQ_NONE:
 903		break;
 904	case RPM_REQ_IDLE:
 905		rpm_idle(dev, RPM_NOWAIT);
 906		break;
 907	case RPM_REQ_SUSPEND:
 908		rpm_suspend(dev, RPM_NOWAIT);
 909		break;
 910	case RPM_REQ_AUTOSUSPEND:
 911		rpm_suspend(dev, RPM_NOWAIT | RPM_AUTO);
 912		break;
 913	case RPM_REQ_RESUME:
 914		rpm_resume(dev, RPM_NOWAIT);
 915		break;
 916	}
 917
 918 out:
 919	spin_unlock_irq(&dev->power.lock);
 920}
 921
 922/**
 923 * pm_suspend_timer_fn - Timer function for pm_schedule_suspend().
 924 * @data: Device pointer passed by pm_schedule_suspend().
 925 *
 926 * Check if the time is right and queue a suspend request.
 927 */
 928static enum hrtimer_restart  pm_suspend_timer_fn(struct hrtimer *timer)
 929{
 930	struct device *dev = container_of(timer, struct device, power.suspend_timer);
 931	unsigned long flags;
 932	u64 expires;
 933
 934	spin_lock_irqsave(&dev->power.lock, flags);
 935
 936	expires = dev->power.timer_expires;
 937	/*
 938	 * If 'expires' is after the current time, we've been called
 939	 * too early.
 940	 */
 941	if (expires > 0 && expires < ktime_get_mono_fast_ns()) {
 942		dev->power.timer_expires = 0;
 943		rpm_suspend(dev, dev->power.timer_autosuspends ?
 944		    (RPM_ASYNC | RPM_AUTO) : RPM_ASYNC);
 945	}
 946
 947	spin_unlock_irqrestore(&dev->power.lock, flags);
 948
 949	return HRTIMER_NORESTART;
 950}
 951
 952/**
 953 * pm_schedule_suspend - Set up a timer to submit a suspend request in future.
 954 * @dev: Device to suspend.
 955 * @delay: Time to wait before submitting a suspend request, in milliseconds.
 956 */
 957int pm_schedule_suspend(struct device *dev, unsigned int delay)
 958{
 959	unsigned long flags;
 960	u64 expires;
 961	int retval;
 962
 963	spin_lock_irqsave(&dev->power.lock, flags);
 964
 965	if (!delay) {
 966		retval = rpm_suspend(dev, RPM_ASYNC);
 967		goto out;
 968	}
 969
 970	retval = rpm_check_suspend_allowed(dev);
 971	if (retval)
 972		goto out;
 973
 974	/* Other scheduled or pending requests need to be canceled. */
 975	pm_runtime_cancel_pending(dev);
 976
 977	expires = ktime_get_mono_fast_ns() + (u64)delay * NSEC_PER_MSEC;
 978	dev->power.timer_expires = expires;
 979	dev->power.timer_autosuspends = 0;
 980	hrtimer_start(&dev->power.suspend_timer, expires, HRTIMER_MODE_ABS);
 981
 982 out:
 983	spin_unlock_irqrestore(&dev->power.lock, flags);
 984
 985	return retval;
 986}
 987EXPORT_SYMBOL_GPL(pm_schedule_suspend);
 988
 989/**
 990 * __pm_runtime_idle - Entry point for runtime idle operations.
 991 * @dev: Device to send idle notification for.
 992 * @rpmflags: Flag bits.
 993 *
 994 * If the RPM_GET_PUT flag is set, decrement the device's usage count and
 995 * return immediately if it is larger than zero.  Then carry out an idle
 996 * notification, either synchronous or asynchronous.
 997 *
 998 * This routine may be called in atomic context if the RPM_ASYNC flag is set,
 999 * or if pm_runtime_irq_safe() has been called.
1000 */
1001int __pm_runtime_idle(struct device *dev, int rpmflags)
1002{
1003	unsigned long flags;
1004	int retval;
1005
1006	if (rpmflags & RPM_GET_PUT) {
1007		if (!atomic_dec_and_test(&dev->power.usage_count)) {
1008			trace_rpm_usage_rcuidle(dev, rpmflags);
1009			return 0;
1010		}
1011	}
1012
1013	might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);
1014
1015	spin_lock_irqsave(&dev->power.lock, flags);
1016	retval = rpm_idle(dev, rpmflags);
1017	spin_unlock_irqrestore(&dev->power.lock, flags);
1018
1019	return retval;
1020}
1021EXPORT_SYMBOL_GPL(__pm_runtime_idle);
1022
1023/**
1024 * __pm_runtime_suspend - Entry point for runtime put/suspend operations.
1025 * @dev: Device to suspend.
1026 * @rpmflags: Flag bits.
1027 *
1028 * If the RPM_GET_PUT flag is set, decrement the device's usage count and
1029 * return immediately if it is larger than zero.  Then carry out a suspend,
1030 * either synchronous or asynchronous.
1031 *
1032 * This routine may be called in atomic context if the RPM_ASYNC flag is set,
1033 * or if pm_runtime_irq_safe() has been called.
1034 */
1035int __pm_runtime_suspend(struct device *dev, int rpmflags)
1036{
1037	unsigned long flags;
1038	int retval;
1039
1040	if (rpmflags & RPM_GET_PUT) {
1041		if (!atomic_dec_and_test(&dev->power.usage_count)) {
1042			trace_rpm_usage_rcuidle(dev, rpmflags);
1043			return 0;
1044		}
1045	}
1046
1047	might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);
1048
1049	spin_lock_irqsave(&dev->power.lock, flags);
1050	retval = rpm_suspend(dev, rpmflags);
1051	spin_unlock_irqrestore(&dev->power.lock, flags);
1052
1053	return retval;
1054}
1055EXPORT_SYMBOL_GPL(__pm_runtime_suspend);
1056
1057/**
1058 * __pm_runtime_resume - Entry point for runtime resume operations.
1059 * @dev: Device to resume.
1060 * @rpmflags: Flag bits.
1061 *
1062 * If the RPM_GET_PUT flag is set, increment the device's usage count.  Then
1063 * carry out a resume, either synchronous or asynchronous.
1064 *
1065 * This routine may be called in atomic context if the RPM_ASYNC flag is set,
1066 * or if pm_runtime_irq_safe() has been called.
1067 */
1068int __pm_runtime_resume(struct device *dev, int rpmflags)
1069{
1070	unsigned long flags;
1071	int retval;
1072
1073	might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe &&
1074			dev->power.runtime_status != RPM_ACTIVE);
1075
1076	if (rpmflags & RPM_GET_PUT)
1077		atomic_inc(&dev->power.usage_count);
1078
1079	spin_lock_irqsave(&dev->power.lock, flags);
1080	retval = rpm_resume(dev, rpmflags);
1081	spin_unlock_irqrestore(&dev->power.lock, flags);
1082
1083	return retval;
1084}
1085EXPORT_SYMBOL_GPL(__pm_runtime_resume);
1086
1087/**
1088 * pm_runtime_get_if_active - Conditionally bump up device usage counter.
1089 * @dev: Device to handle.
1090 * @ign_usage_count: Whether or not to look at the current usage counter value.
1091 *
1092 * Return -EINVAL if runtime PM is disabled for @dev.
1093 *
1094 * Otherwise, if the runtime PM status of @dev is %RPM_ACTIVE and either
1095 * @ign_usage_count is %true or the runtime PM usage counter of @dev is not
1096 * zero, increment the usage counter of @dev and return 1. Otherwise, return 0
1097 * without changing the usage counter.
1098 *
1099 * If @ign_usage_count is %true, this function can be used to prevent suspending
1100 * the device when its runtime PM status is %RPM_ACTIVE.
1101 *
1102 * If @ign_usage_count is %false, this function can be used to prevent
1103 * suspending the device when both its runtime PM status is %RPM_ACTIVE and its
1104 * runtime PM usage counter is not zero.
1105 *
1106 * The caller is resposible for decrementing the runtime PM usage counter of
1107 * @dev after this function has returned a positive value for it.
1108 */
1109int pm_runtime_get_if_active(struct device *dev, bool ign_usage_count)
1110{
1111	unsigned long flags;
1112	int retval;
1113
1114	spin_lock_irqsave(&dev->power.lock, flags);
1115	if (dev->power.disable_depth > 0) {
1116		retval = -EINVAL;
1117	} else if (dev->power.runtime_status != RPM_ACTIVE) {
1118		retval = 0;
1119	} else if (ign_usage_count) {
1120		retval = 1;
1121		atomic_inc(&dev->power.usage_count);
1122	} else {
1123		retval = atomic_inc_not_zero(&dev->power.usage_count);
1124	}
1125	trace_rpm_usage_rcuidle(dev, 0);
1126	spin_unlock_irqrestore(&dev->power.lock, flags);
1127
1128	return retval;
1129}
1130EXPORT_SYMBOL_GPL(pm_runtime_get_if_active);
1131
1132/**
1133 * __pm_runtime_set_status - Set runtime PM status of a device.
1134 * @dev: Device to handle.
1135 * @status: New runtime PM status of the device.
1136 *
1137 * If runtime PM of the device is disabled or its power.runtime_error field is
1138 * different from zero, the status may be changed either to RPM_ACTIVE, or to
1139 * RPM_SUSPENDED, as long as that reflects the actual state of the device.
1140 * However, if the device has a parent and the parent is not active, and the
1141 * parent's power.ignore_children flag is unset, the device's status cannot be
1142 * set to RPM_ACTIVE, so -EBUSY is returned in that case.
1143 *
1144 * If successful, __pm_runtime_set_status() clears the power.runtime_error field
1145 * and the device parent's counter of unsuspended children is modified to
1146 * reflect the new status.  If the new status is RPM_SUSPENDED, an idle
1147 * notification request for the parent is submitted.
1148 *
1149 * If @dev has any suppliers (as reflected by device links to them), and @status
1150 * is RPM_ACTIVE, they will be activated upfront and if the activation of one
1151 * of them fails, the status of @dev will be changed to RPM_SUSPENDED (instead
1152 * of the @status value) and the suppliers will be deacticated on exit.  The
1153 * error returned by the failing supplier activation will be returned in that
1154 * case.
1155 */
1156int __pm_runtime_set_status(struct device *dev, unsigned int status)
1157{
1158	struct device *parent = dev->parent;
1159	bool notify_parent = false;
1160	int error = 0;
1161
1162	if (status != RPM_ACTIVE && status != RPM_SUSPENDED)
1163		return -EINVAL;
1164
1165	spin_lock_irq(&dev->power.lock);
1166
1167	/*
1168	 * Prevent PM-runtime from being enabled for the device or return an
1169	 * error if it is enabled already and working.
1170	 */
1171	if (dev->power.runtime_error || dev->power.disable_depth)
1172		dev->power.disable_depth++;
1173	else
1174		error = -EAGAIN;
1175
1176	spin_unlock_irq(&dev->power.lock);
1177
1178	if (error)
1179		return error;
1180
1181	/*
1182	 * If the new status is RPM_ACTIVE, the suppliers can be activated
1183	 * upfront regardless of the current status, because next time
1184	 * rpm_put_suppliers() runs, the rpm_active refcounts of the links
1185	 * involved will be dropped down to one anyway.
1186	 */
1187	if (status == RPM_ACTIVE) {
1188		int idx = device_links_read_lock();
1189
1190		error = rpm_get_suppliers(dev);
1191		if (error)
1192			status = RPM_SUSPENDED;
1193
1194		device_links_read_unlock(idx);
1195	}
1196
1197	spin_lock_irq(&dev->power.lock);
1198
1199	if (dev->power.runtime_status == status || !parent)
1200		goto out_set;
1201
1202	if (status == RPM_SUSPENDED) {
1203		atomic_add_unless(&parent->power.child_count, -1, 0);
1204		notify_parent = !parent->power.ignore_children;
1205	} else {
1206		spin_lock_nested(&parent->power.lock, SINGLE_DEPTH_NESTING);
1207
1208		/*
1209		 * It is invalid to put an active child under a parent that is
1210		 * not active, has runtime PM enabled and the
1211		 * 'power.ignore_children' flag unset.
1212		 */
1213		if (!parent->power.disable_depth
1214		    && !parent->power.ignore_children
1215		    && parent->power.runtime_status != RPM_ACTIVE) {
1216			dev_err(dev, "runtime PM trying to activate child device %s but parent (%s) is not active\n",
1217				dev_name(dev),
1218				dev_name(parent));
1219			error = -EBUSY;
1220		} else if (dev->power.runtime_status == RPM_SUSPENDED) {
1221			atomic_inc(&parent->power.child_count);
1222		}
1223
1224		spin_unlock(&parent->power.lock);
1225
1226		if (error) {
1227			status = RPM_SUSPENDED;
1228			goto out;
1229		}
1230	}
1231
1232 out_set:
1233	__update_runtime_status(dev, status);
1234	if (!error)
1235		dev->power.runtime_error = 0;
1236
1237 out:
1238	spin_unlock_irq(&dev->power.lock);
1239
1240	if (notify_parent)
1241		pm_request_idle(parent);
1242
1243	if (status == RPM_SUSPENDED) {
1244		int idx = device_links_read_lock();
1245
1246		rpm_put_suppliers(dev);
1247
1248		device_links_read_unlock(idx);
1249	}
1250
1251	pm_runtime_enable(dev);
1252
1253	return error;
1254}
1255EXPORT_SYMBOL_GPL(__pm_runtime_set_status);
1256
1257/**
1258 * __pm_runtime_barrier - Cancel pending requests and wait for completions.
1259 * @dev: Device to handle.
1260 *
1261 * Flush all pending requests for the device from pm_wq and wait for all
1262 * runtime PM operations involving the device in progress to complete.
1263 *
1264 * Should be called under dev->power.lock with interrupts disabled.
1265 */
1266static void __pm_runtime_barrier(struct device *dev)
1267{
1268	pm_runtime_deactivate_timer(dev);
1269
1270	if (dev->power.request_pending) {
1271		dev->power.request = RPM_REQ_NONE;
1272		spin_unlock_irq(&dev->power.lock);
1273
1274		cancel_work_sync(&dev->power.work);
1275
1276		spin_lock_irq(&dev->power.lock);
1277		dev->power.request_pending = false;
1278	}
1279
1280	if (dev->power.runtime_status == RPM_SUSPENDING
1281	    || dev->power.runtime_status == RPM_RESUMING
1282	    || dev->power.idle_notification) {
1283		DEFINE_WAIT(wait);
1284
1285		/* Suspend, wake-up or idle notification in progress. */
1286		for (;;) {
1287			prepare_to_wait(&dev->power.wait_queue, &wait,
1288					TASK_UNINTERRUPTIBLE);
1289			if (dev->power.runtime_status != RPM_SUSPENDING
1290			    && dev->power.runtime_status != RPM_RESUMING
1291			    && !dev->power.idle_notification)
1292				break;
1293			spin_unlock_irq(&dev->power.lock);
1294
1295			schedule();
1296
1297			spin_lock_irq(&dev->power.lock);
1298		}
1299		finish_wait(&dev->power.wait_queue, &wait);
1300	}
1301}
1302
1303/**
1304 * pm_runtime_barrier - Flush pending requests and wait for completions.
1305 * @dev: Device to handle.
1306 *
1307 * Prevent the device from being suspended by incrementing its usage counter and
1308 * if there's a pending resume request for the device, wake the device up.
1309 * Next, make sure that all pending requests for the device have been flushed
1310 * from pm_wq and wait for all runtime PM operations involving the device in
1311 * progress to complete.
1312 *
1313 * Return value:
1314 * 1, if there was a resume request pending and the device had to be woken up,
1315 * 0, otherwise
1316 */
1317int pm_runtime_barrier(struct device *dev)
1318{
1319	int retval = 0;
1320
1321	pm_runtime_get_noresume(dev);
1322	spin_lock_irq(&dev->power.lock);
1323
1324	if (dev->power.request_pending
1325	    && dev->power.request == RPM_REQ_RESUME) {
1326		rpm_resume(dev, 0);
1327		retval = 1;
1328	}
1329
1330	__pm_runtime_barrier(dev);
1331
1332	spin_unlock_irq(&dev->power.lock);
1333	pm_runtime_put_noidle(dev);
1334
1335	return retval;
1336}
1337EXPORT_SYMBOL_GPL(pm_runtime_barrier);
1338
1339/**
1340 * __pm_runtime_disable - Disable runtime PM of a device.
1341 * @dev: Device to handle.
1342 * @check_resume: If set, check if there's a resume request for the device.
1343 *
1344 * Increment power.disable_depth for the device and if it was zero previously,
1345 * cancel all pending runtime PM requests for the device and wait for all
1346 * operations in progress to complete.  The device can be either active or
1347 * suspended after its runtime PM has been disabled.
1348 *
1349 * If @check_resume is set and there's a resume request pending when
1350 * __pm_runtime_disable() is called and power.disable_depth is zero, the
1351 * function will wake up the device before disabling its runtime PM.
1352 */
1353void __pm_runtime_disable(struct device *dev, bool check_resume)
1354{
1355	spin_lock_irq(&dev->power.lock);
1356
1357	if (dev->power.disable_depth > 0) {
1358		dev->power.disable_depth++;
1359		goto out;
1360	}
1361
1362	/*
1363	 * Wake up the device if there's a resume request pending, because that
1364	 * means there probably is some I/O to process and disabling runtime PM
1365	 * shouldn't prevent the device from processing the I/O.
1366	 */
1367	if (check_resume && dev->power.request_pending
1368	    && dev->power.request == RPM_REQ_RESUME) {
1369		/*
1370		 * Prevent suspends and idle notifications from being carried
1371		 * out after we have woken up the device.
1372		 */
1373		pm_runtime_get_noresume(dev);
1374
1375		rpm_resume(dev, 0);
1376
1377		pm_runtime_put_noidle(dev);
1378	}
1379
1380	/* Update time accounting before disabling PM-runtime. */
1381	update_pm_runtime_accounting(dev);
1382
1383	if (!dev->power.disable_depth++)
1384		__pm_runtime_barrier(dev);
1385
1386 out:
1387	spin_unlock_irq(&dev->power.lock);
1388}
1389EXPORT_SYMBOL_GPL(__pm_runtime_disable);
1390
1391/**
1392 * pm_runtime_enable - Enable runtime PM of a device.
1393 * @dev: Device to handle.
1394 */
1395void pm_runtime_enable(struct device *dev)
1396{
1397	unsigned long flags;
1398
1399	spin_lock_irqsave(&dev->power.lock, flags);
1400
1401	if (dev->power.disable_depth > 0) {
1402		dev->power.disable_depth--;
1403
1404		/* About to enable runtime pm, set accounting_timestamp to now */
1405		if (!dev->power.disable_depth)
1406			dev->power.accounting_timestamp = ktime_get_mono_fast_ns();
1407	} else {
1408		dev_warn(dev, "Unbalanced %s!\n", __func__);
1409	}
1410
1411	WARN(!dev->power.disable_depth &&
1412	     dev->power.runtime_status == RPM_SUSPENDED &&
1413	     !dev->power.ignore_children &&
1414	     atomic_read(&dev->power.child_count) > 0,
1415	     "Enabling runtime PM for inactive device (%s) with active children\n",
1416	     dev_name(dev));
1417
1418	spin_unlock_irqrestore(&dev->power.lock, flags);
1419}
1420EXPORT_SYMBOL_GPL(pm_runtime_enable);
1421
1422/**
1423 * pm_runtime_forbid - Block runtime PM of a device.
1424 * @dev: Device to handle.
1425 *
1426 * Increase the device's usage count and clear its power.runtime_auto flag,
1427 * so that it cannot be suspended at run time until pm_runtime_allow() is called
1428 * for it.
1429 */
1430void pm_runtime_forbid(struct device *dev)
1431{
1432	spin_lock_irq(&dev->power.lock);
1433	if (!dev->power.runtime_auto)
1434		goto out;
1435
1436	dev->power.runtime_auto = false;
1437	atomic_inc(&dev->power.usage_count);
1438	rpm_resume(dev, 0);
1439
1440 out:
1441	spin_unlock_irq(&dev->power.lock);
1442}
1443EXPORT_SYMBOL_GPL(pm_runtime_forbid);
1444
1445/**
1446 * pm_runtime_allow - Unblock runtime PM of a device.
1447 * @dev: Device to handle.
1448 *
1449 * Decrease the device's usage count and set its power.runtime_auto flag.
1450 */
1451void pm_runtime_allow(struct device *dev)
1452{
1453	spin_lock_irq(&dev->power.lock);
1454	if (dev->power.runtime_auto)
1455		goto out;
1456
1457	dev->power.runtime_auto = true;
1458	if (atomic_dec_and_test(&dev->power.usage_count))
1459		rpm_idle(dev, RPM_AUTO | RPM_ASYNC);
1460	else
1461		trace_rpm_usage_rcuidle(dev, RPM_AUTO | RPM_ASYNC);
1462
1463 out:
1464	spin_unlock_irq(&dev->power.lock);
1465}
1466EXPORT_SYMBOL_GPL(pm_runtime_allow);
1467
1468/**
1469 * pm_runtime_no_callbacks - Ignore runtime PM callbacks for a device.
1470 * @dev: Device to handle.
1471 *
1472 * Set the power.no_callbacks flag, which tells the PM core that this
1473 * device is power-managed through its parent and has no runtime PM
1474 * callbacks of its own.  The runtime sysfs attributes will be removed.
1475 */
1476void pm_runtime_no_callbacks(struct device *dev)
1477{
1478	spin_lock_irq(&dev->power.lock);
1479	dev->power.no_callbacks = 1;
1480	spin_unlock_irq(&dev->power.lock);
1481	if (device_is_registered(dev))
1482		rpm_sysfs_remove(dev);
1483}
1484EXPORT_SYMBOL_GPL(pm_runtime_no_callbacks);
1485
1486/**
1487 * pm_runtime_irq_safe - Leave interrupts disabled during callbacks.
1488 * @dev: Device to handle
1489 *
1490 * Set the power.irq_safe flag, which tells the PM core that the
1491 * ->runtime_suspend() and ->runtime_resume() callbacks for this device should
1492 * always be invoked with the spinlock held and interrupts disabled.  It also
1493 * causes the parent's usage counter to be permanently incremented, preventing
1494 * the parent from runtime suspending -- otherwise an irq-safe child might have
1495 * to wait for a non-irq-safe parent.
1496 */
1497void pm_runtime_irq_safe(struct device *dev)
1498{
1499	if (dev->parent)
1500		pm_runtime_get_sync(dev->parent);
1501	spin_lock_irq(&dev->power.lock);
1502	dev->power.irq_safe = 1;
1503	spin_unlock_irq(&dev->power.lock);
1504}
1505EXPORT_SYMBOL_GPL(pm_runtime_irq_safe);
1506
1507/**
1508 * update_autosuspend - Handle a change to a device's autosuspend settings.
1509 * @dev: Device to handle.
1510 * @old_delay: The former autosuspend_delay value.
1511 * @old_use: The former use_autosuspend value.
1512 *
1513 * Prevent runtime suspend if the new delay is negative and use_autosuspend is
1514 * set; otherwise allow it.  Send an idle notification if suspends are allowed.
1515 *
1516 * This function must be called under dev->power.lock with interrupts disabled.
1517 */
1518static void update_autosuspend(struct device *dev, int old_delay, int old_use)
1519{
1520	int delay = dev->power.autosuspend_delay;
1521
1522	/* Should runtime suspend be prevented now? */
1523	if (dev->power.use_autosuspend && delay < 0) {
1524
1525		/* If it used to be allowed then prevent it. */
1526		if (!old_use || old_delay >= 0) {
1527			atomic_inc(&dev->power.usage_count);
1528			rpm_resume(dev, 0);
1529		} else {
1530			trace_rpm_usage_rcuidle(dev, 0);
1531		}
1532	}
1533
1534	/* Runtime suspend should be allowed now. */
1535	else {
1536
1537		/* If it used to be prevented then allow it. */
1538		if (old_use && old_delay < 0)
1539			atomic_dec(&dev->power.usage_count);
1540
1541		/* Maybe we can autosuspend now. */
1542		rpm_idle(dev, RPM_AUTO);
1543	}
1544}
1545
1546/**
1547 * pm_runtime_set_autosuspend_delay - Set a device's autosuspend_delay value.
1548 * @dev: Device to handle.
1549 * @delay: Value of the new delay in milliseconds.
1550 *
1551 * Set the device's power.autosuspend_delay value.  If it changes to negative
1552 * and the power.use_autosuspend flag is set, prevent runtime suspends.  If it
1553 * changes the other way, allow runtime suspends.
1554 */
1555void pm_runtime_set_autosuspend_delay(struct device *dev, int delay)
1556{
1557	int old_delay, old_use;
1558
1559	spin_lock_irq(&dev->power.lock);
1560	old_delay = dev->power.autosuspend_delay;
1561	old_use = dev->power.use_autosuspend;
1562	dev->power.autosuspend_delay = delay;
1563	update_autosuspend(dev, old_delay, old_use);
1564	spin_unlock_irq(&dev->power.lock);
1565}
1566EXPORT_SYMBOL_GPL(pm_runtime_set_autosuspend_delay);
1567
1568/**
1569 * __pm_runtime_use_autosuspend - Set a device's use_autosuspend flag.
1570 * @dev: Device to handle.
1571 * @use: New value for use_autosuspend.
1572 *
1573 * Set the device's power.use_autosuspend flag, and allow or prevent runtime
1574 * suspends as needed.
1575 */
1576void __pm_runtime_use_autosuspend(struct device *dev, bool use)
1577{
1578	int old_delay, old_use;
1579
1580	spin_lock_irq(&dev->power.lock);
1581	old_delay = dev->power.autosuspend_delay;
1582	old_use = dev->power.use_autosuspend;
1583	dev->power.use_autosuspend = use;
1584	update_autosuspend(dev, old_delay, old_use);
1585	spin_unlock_irq(&dev->power.lock);
1586}
1587EXPORT_SYMBOL_GPL(__pm_runtime_use_autosuspend);
1588
1589/**
1590 * pm_runtime_init - Initialize runtime PM fields in given device object.
1591 * @dev: Device object to initialize.
1592 */
1593void pm_runtime_init(struct device *dev)
1594{
1595	dev->power.runtime_status = RPM_SUSPENDED;
1596	dev->power.idle_notification = false;
1597
1598	dev->power.disable_depth = 1;
1599	atomic_set(&dev->power.usage_count, 0);
1600
1601	dev->power.runtime_error = 0;
1602
1603	atomic_set(&dev->power.child_count, 0);
1604	pm_suspend_ignore_children(dev, false);
1605	dev->power.runtime_auto = true;
1606
1607	dev->power.request_pending = false;
1608	dev->power.request = RPM_REQ_NONE;
1609	dev->power.deferred_resume = false;
1610	INIT_WORK(&dev->power.work, pm_runtime_work);
1611
1612	dev->power.timer_expires = 0;
1613	hrtimer_init(&dev->power.suspend_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
1614	dev->power.suspend_timer.function = pm_suspend_timer_fn;
1615
1616	init_waitqueue_head(&dev->power.wait_queue);
1617}
1618
1619/**
1620 * pm_runtime_reinit - Re-initialize runtime PM fields in given device object.
1621 * @dev: Device object to re-initialize.
1622 */
1623void pm_runtime_reinit(struct device *dev)
1624{
1625	if (!pm_runtime_enabled(dev)) {
1626		if (dev->power.runtime_status == RPM_ACTIVE)
1627			pm_runtime_set_suspended(dev);
1628		if (dev->power.irq_safe) {
1629			spin_lock_irq(&dev->power.lock);
1630			dev->power.irq_safe = 0;
1631			spin_unlock_irq(&dev->power.lock);
1632			if (dev->parent)
1633				pm_runtime_put(dev->parent);
1634		}
1635	}
1636}
1637
1638/**
1639 * pm_runtime_remove - Prepare for removing a device from device hierarchy.
1640 * @dev: Device object being removed from device hierarchy.
1641 */
1642void pm_runtime_remove(struct device *dev)
1643{
1644	__pm_runtime_disable(dev, false);
1645	pm_runtime_reinit(dev);
1646}
1647
1648/**
1649 * pm_runtime_clean_up_links - Prepare links to consumers for driver removal.
1650 * @dev: Device whose driver is going to be removed.
1651 *
1652 * Check links from this device to any consumers and if any of them have active
1653 * runtime PM references to the device, drop the usage counter of the device
1654 * (as many times as needed).
1655 *
1656 * Links with the DL_FLAG_MANAGED flag unset are ignored.
1657 *
1658 * Since the device is guaranteed to be runtime-active at the point this is
1659 * called, nothing else needs to be done here.
1660 *
1661 * Moreover, this is called after device_links_busy() has returned 'false', so
1662 * the status of each link is guaranteed to be DL_STATE_SUPPLIER_UNBIND and
1663 * therefore rpm_active can't be manipulated concurrently.
1664 */
1665void pm_runtime_clean_up_links(struct device *dev)
1666{
1667	struct device_link *link;
1668	int idx;
1669
1670	idx = device_links_read_lock();
1671
1672	list_for_each_entry_rcu(link, &dev->links.consumers, s_node,
1673				device_links_read_lock_held()) {
1674		if (!(link->flags & DL_FLAG_MANAGED))
1675			continue;
1676
1677		while (refcount_dec_not_one(&link->rpm_active))
1678			pm_runtime_put_noidle(dev);
1679	}
1680
1681	device_links_read_unlock(idx);
1682}
1683
1684/**
1685 * pm_runtime_get_suppliers - Resume and reference-count supplier devices.
1686 * @dev: Consumer device.
1687 */
1688void pm_runtime_get_suppliers(struct device *dev)
1689{
1690	struct device_link *link;
1691	int idx;
1692
1693	idx = device_links_read_lock();
1694
1695	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
1696				device_links_read_lock_held())
1697		if (link->flags & DL_FLAG_PM_RUNTIME) {
1698			link->supplier_preactivated = true;
1699			refcount_inc(&link->rpm_active);
1700			pm_runtime_get_sync(link->supplier);
1701		}
1702
1703	device_links_read_unlock(idx);
1704}
1705
1706/**
1707 * pm_runtime_put_suppliers - Drop references to supplier devices.
1708 * @dev: Consumer device.
1709 */
1710void pm_runtime_put_suppliers(struct device *dev)
1711{
1712	struct device_link *link;
1713	int idx;
1714
1715	idx = device_links_read_lock();
1716
1717	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
1718				device_links_read_lock_held())
1719		if (link->supplier_preactivated) {
1720			link->supplier_preactivated = false;
1721			if (refcount_dec_not_one(&link->rpm_active))
1722				pm_runtime_put(link->supplier);
1723		}
1724
1725	device_links_read_unlock(idx);
1726}
1727
1728void pm_runtime_new_link(struct device *dev)
1729{
1730	spin_lock_irq(&dev->power.lock);
1731	dev->power.links_count++;
1732	spin_unlock_irq(&dev->power.lock);
1733}
1734
1735void pm_runtime_drop_link(struct device *dev)
1736{
1737	spin_lock_irq(&dev->power.lock);
1738	WARN_ON(dev->power.links_count == 0);
1739	dev->power.links_count--;
1740	spin_unlock_irq(&dev->power.lock);
1741}
1742
1743static bool pm_runtime_need_not_resume(struct device *dev)
1744{
1745	return atomic_read(&dev->power.usage_count) <= 1 &&
1746		(atomic_read(&dev->power.child_count) == 0 ||
1747		 dev->power.ignore_children);
1748}
1749
1750/**
1751 * pm_runtime_force_suspend - Force a device into suspend state if needed.
1752 * @dev: Device to suspend.
1753 *
1754 * Disable runtime PM so we safely can check the device's runtime PM status and
1755 * if it is active, invoke its ->runtime_suspend callback to suspend it and
1756 * change its runtime PM status field to RPM_SUSPENDED.  Also, if the device's
1757 * usage and children counters don't indicate that the device was in use before
1758 * the system-wide transition under way, decrement its parent's children counter
1759 * (if there is a parent).  Keep runtime PM disabled to preserve the state
1760 * unless we encounter errors.
1761 *
1762 * Typically this function may be invoked from a system suspend callback to make
1763 * sure the device is put into low power state and it should only be used during
1764 * system-wide PM transitions to sleep states.  It assumes that the analogous
1765 * pm_runtime_force_resume() will be used to resume the device.
1766 */
1767int pm_runtime_force_suspend(struct device *dev)
1768{
1769	int (*callback)(struct device *);
1770	int ret;
1771
1772	pm_runtime_disable(dev);
1773	if (pm_runtime_status_suspended(dev))
1774		return 0;
1775
1776	callback = RPM_GET_CALLBACK(dev, runtime_suspend);
1777
1778	ret = callback ? callback(dev) : 0;
1779	if (ret)
1780		goto err;
1781
1782	/*
1783	 * If the device can stay in suspend after the system-wide transition
1784	 * to the working state that will follow, drop the children counter of
1785	 * its parent, but set its status to RPM_SUSPENDED anyway in case this
1786	 * function will be called again for it in the meantime.
1787	 */
1788	if (pm_runtime_need_not_resume(dev))
1789		pm_runtime_set_suspended(dev);
1790	else
1791		__update_runtime_status(dev, RPM_SUSPENDED);
1792
1793	return 0;
1794
1795err:
1796	pm_runtime_enable(dev);
1797	return ret;
1798}
1799EXPORT_SYMBOL_GPL(pm_runtime_force_suspend);
1800
1801/**
1802 * pm_runtime_force_resume - Force a device into resume state if needed.
1803 * @dev: Device to resume.
1804 *
1805 * Prior invoking this function we expect the user to have brought the device
1806 * into low power state by a call to pm_runtime_force_suspend(). Here we reverse
1807 * those actions and bring the device into full power, if it is expected to be
1808 * used on system resume.  In the other case, we defer the resume to be managed
1809 * via runtime PM.
1810 *
1811 * Typically this function may be invoked from a system resume callback.
1812 */
1813int pm_runtime_force_resume(struct device *dev)
1814{
1815	int (*callback)(struct device *);
1816	int ret = 0;
1817
1818	if (!pm_runtime_status_suspended(dev) || pm_runtime_need_not_resume(dev))
1819		goto out;
1820
1821	/*
1822	 * The value of the parent's children counter is correct already, so
1823	 * just update the status of the device.
1824	 */
1825	__update_runtime_status(dev, RPM_ACTIVE);
1826
1827	callback = RPM_GET_CALLBACK(dev, runtime_resume);
1828
1829	ret = callback ? callback(dev) : 0;
1830	if (ret) {
1831		pm_runtime_set_suspended(dev);
1832		goto out;
1833	}
1834
1835	pm_runtime_mark_last_busy(dev);
1836out:
1837	pm_runtime_enable(dev);
1838	return ret;
1839}
1840EXPORT_SYMBOL_GPL(pm_runtime_force_resume);