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 <linux/rculist.h>
  15#include <trace/events/rpm.h>
  16
  17#include "../base.h"
  18#include "power.h"
  19
  20typedef int (*pm_callback_t)(struct device *);
  21
  22static pm_callback_t __rpm_get_callback(struct device *dev, size_t cb_offset)
  23{
  24	pm_callback_t cb;
  25	const struct dev_pm_ops *ops;
  26
  27	if (dev->pm_domain)
  28		ops = &dev->pm_domain->ops;
  29	else if (dev->type && dev->type->pm)
  30		ops = dev->type->pm;
  31	else if (dev->class && dev->class->pm)
  32		ops = dev->class->pm;
  33	else if (dev->bus && dev->bus->pm)
  34		ops = dev->bus->pm;
  35	else
  36		ops = NULL;
  37
  38	if (ops)
  39		cb = *(pm_callback_t *)((void *)ops + cb_offset);
  40	else
  41		cb = NULL;
  42
  43	if (!cb && dev->driver && dev->driver->pm)
  44		cb = *(pm_callback_t *)((void *)dev->driver->pm + cb_offset);
  45
  46	return cb;
  47}
  48
  49#define RPM_GET_CALLBACK(dev, callback) \
  50		__rpm_get_callback(dev, offsetof(struct dev_pm_ops, callback))
  51
  52static int rpm_resume(struct device *dev, int rpmflags);
  53static int rpm_suspend(struct device *dev, int rpmflags);
  54
  55/**
  56 * update_pm_runtime_accounting - Update the time accounting of power states
  57 * @dev: Device to update the accounting for
  58 *
  59 * In order to be able to have time accounting of the various power states
  60 * (as used by programs such as PowerTOP to show the effectiveness of runtime
  61 * PM), we need to track the time spent in each state.
  62 * update_pm_runtime_accounting must be called each time before the
  63 * runtime_status field is updated, to account the time in the old state
  64 * correctly.
  65 */
  66static void update_pm_runtime_accounting(struct device *dev)
  67{
  68	u64 now, last, delta;
  69
  70	if (dev->power.disable_depth > 0)
  71		return;
  72
  73	last = dev->power.accounting_timestamp;
  74
  75	now = ktime_get_mono_fast_ns();
  76	dev->power.accounting_timestamp = now;
  77
  78	/*
  79	 * Because ktime_get_mono_fast_ns() is not monotonic during
  80	 * timekeeping updates, ensure that 'now' is after the last saved
  81	 * timesptamp.
  82	 */
  83	if (now < last)
  84		return;
  85
  86	delta = now - last;
  87
  88	if (dev->power.runtime_status == RPM_SUSPENDED)
  89		dev->power.suspended_time += delta;
  90	else
  91		dev->power.active_time += delta;
  92}
  93
  94static void __update_runtime_status(struct device *dev, enum rpm_status status)
  95{
  96	update_pm_runtime_accounting(dev);
 
  97	dev->power.runtime_status = status;
  98}
  99
 100static u64 rpm_get_accounted_time(struct device *dev, bool suspended)
 101{
 102	u64 time;
 103	unsigned long flags;
 104
 105	spin_lock_irqsave(&dev->power.lock, flags);
 106
 107	update_pm_runtime_accounting(dev);
 108	time = suspended ? dev->power.suspended_time : dev->power.active_time;
 109
 110	spin_unlock_irqrestore(&dev->power.lock, flags);
 111
 112	return time;
 113}
 114
 115u64 pm_runtime_active_time(struct device *dev)
 116{
 117	return rpm_get_accounted_time(dev, false);
 118}
 119
 120u64 pm_runtime_suspended_time(struct device *dev)
 121{
 122	return rpm_get_accounted_time(dev, true);
 123}
 124EXPORT_SYMBOL_GPL(pm_runtime_suspended_time);
 125
 126/**
 127 * pm_runtime_deactivate_timer - Deactivate given device's suspend timer.
 128 * @dev: Device to handle.
 129 */
 130static void pm_runtime_deactivate_timer(struct device *dev)
 131{
 132	if (dev->power.timer_expires > 0) {
 133		hrtimer_try_to_cancel(&dev->power.suspend_timer);
 134		dev->power.timer_expires = 0;
 135	}
 136}
 137
 138/**
 139 * pm_runtime_cancel_pending - Deactivate suspend timer and cancel requests.
 140 * @dev: Device to handle.
 141 */
 142static void pm_runtime_cancel_pending(struct device *dev)
 143{
 144	pm_runtime_deactivate_timer(dev);
 145	/*
 146	 * In case there's a request pending, make sure its work function will
 147	 * return without doing anything.
 148	 */
 149	dev->power.request = RPM_REQ_NONE;
 150}
 151
 152/*
 153 * pm_runtime_autosuspend_expiration - Get a device's autosuspend-delay expiration time.
 154 * @dev: Device to handle.
 155 *
 156 * Compute the autosuspend-delay expiration time based on the device's
 157 * power.last_busy time.  If the delay has already expired or is disabled
 158 * (negative) or the power.use_autosuspend flag isn't set, return 0.
 159 * Otherwise return the expiration time in nanoseconds (adjusted to be nonzero).
 160 *
 161 * This function may be called either with or without dev->power.lock held.
 162 * Either way it can be racy, since power.last_busy may be updated at any time.
 163 */
 164u64 pm_runtime_autosuspend_expiration(struct device *dev)
 165{
 166	int autosuspend_delay;
 167	u64 expires;
 168
 169	if (!dev->power.use_autosuspend)
 170		return 0;
 171
 172	autosuspend_delay = READ_ONCE(dev->power.autosuspend_delay);
 173	if (autosuspend_delay < 0)
 174		return 0;
 175
 176	expires  = READ_ONCE(dev->power.last_busy);
 177	expires += (u64)autosuspend_delay * NSEC_PER_MSEC;
 178	if (expires > ktime_get_mono_fast_ns())
 179		return expires;	/* Expires in the future */
 180
 181	return 0;
 182}
 183EXPORT_SYMBOL_GPL(pm_runtime_autosuspend_expiration);
 184
 185static int dev_memalloc_noio(struct device *dev, void *data)
 186{
 187	return dev->power.memalloc_noio;
 188}
 189
 190/*
 191 * pm_runtime_set_memalloc_noio - Set a device's memalloc_noio flag.
 192 * @dev: Device to handle.
 193 * @enable: True for setting the flag and False for clearing the flag.
 194 *
 195 * Set the flag for all devices in the path from the device to the
 196 * root device in the device tree if @enable is true, otherwise clear
 197 * the flag for devices in the path whose siblings don't set the flag.
 198 *
 199 * The function should only be called by block device, or network
 200 * device driver for solving the deadlock problem during runtime
 201 * resume/suspend:
 202 *
 203 *     If memory allocation with GFP_KERNEL is called inside runtime
 204 *     resume/suspend callback of any one of its ancestors(or the
 205 *     block device itself), the deadlock may be triggered inside the
 206 *     memory allocation since it might not complete until the block
 207 *     device becomes active and the involed page I/O finishes. The
 208 *     situation is pointed out first by Alan Stern. Network device
 209 *     are involved in iSCSI kind of situation.
 210 *
 211 * The lock of dev_hotplug_mutex is held in the function for handling
 212 * hotplug race because pm_runtime_set_memalloc_noio() may be called
 213 * in async probe().
 214 *
 215 * The function should be called between device_add() and device_del()
 216 * on the affected device(block/network device).
 217 */
 218void pm_runtime_set_memalloc_noio(struct device *dev, bool enable)
 219{
 220	static DEFINE_MUTEX(dev_hotplug_mutex);
 221
 222	mutex_lock(&dev_hotplug_mutex);
 223	for (;;) {
 224		bool enabled;
 225
 226		/* hold power lock since bitfield is not SMP-safe. */
 227		spin_lock_irq(&dev->power.lock);
 228		enabled = dev->power.memalloc_noio;
 229		dev->power.memalloc_noio = enable;
 230		spin_unlock_irq(&dev->power.lock);
 231
 232		/*
 233		 * not need to enable ancestors any more if the device
 234		 * has been enabled.
 235		 */
 236		if (enabled && enable)
 237			break;
 238
 239		dev = dev->parent;
 240
 241		/*
 242		 * clear flag of the parent device only if all the
 243		 * children don't set the flag because ancestor's
 244		 * flag was set by any one of the descendants.
 245		 */
 246		if (!dev || (!enable &&
 247		    device_for_each_child(dev, NULL, 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))
 267		retval = -EAGAIN;
 268	else if (!dev->power.ignore_children && atomic_read(&dev->power.child_count))
 269		retval = -EBUSY;
 270
 271	/* Pending resume requests take precedence over suspends. */
 272	else if ((dev->power.deferred_resume &&
 273	    dev->power.runtime_status == RPM_SUSPENDING) ||
 274	    (dev->power.request_pending && dev->power.request == RPM_REQ_RESUME))
 275		retval = -EAGAIN;
 276	else if (__dev_pm_qos_resume_latency(dev) == 0)
 277		retval = -EPERM;
 278	else if (dev->power.runtime_status == RPM_SUSPENDED)
 279		retval = 1;
 280
 281	return retval;
 282}
 283
 284static int rpm_get_suppliers(struct device *dev)
 285{
 286	struct device_link *link;
 287
 288	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
 289				device_links_read_lock_held()) {
 290		int retval;
 291
 292		if (!(link->flags & DL_FLAG_PM_RUNTIME))
 293			continue;
 294
 295		retval = pm_runtime_get_sync(link->supplier);
 296		/* Ignore suppliers with disabled runtime PM. */
 297		if (retval < 0 && retval != -EACCES) {
 298			pm_runtime_put_noidle(link->supplier);
 299			return retval;
 300		}
 301		refcount_inc(&link->rpm_active);
 302	}
 303	return 0;
 304}
 305
 306/**
 307 * pm_runtime_release_supplier - Drop references to device link's supplier.
 308 * @link: Target device link.
 309 *
 310 * Drop all runtime PM references associated with @link to its supplier device.
 311 */
 312void pm_runtime_release_supplier(struct device_link *link)
 313{
 314	struct device *supplier = link->supplier;
 315
 316	/*
 317	 * The additional power.usage_count check is a safety net in case
 318	 * the rpm_active refcount becomes saturated, in which case
 319	 * refcount_dec_not_one() would return true forever, but it is not
 320	 * strictly necessary.
 321	 */
 322	while (refcount_dec_not_one(&link->rpm_active) &&
 323	       atomic_read(&supplier->power.usage_count) > 0)
 324		pm_runtime_put_noidle(supplier);
 325}
 326
 327static void __rpm_put_suppliers(struct device *dev, bool try_to_suspend)
 328{
 329	struct device_link *link;
 330
 331	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
 332				device_links_read_lock_held()) {
 333		pm_runtime_release_supplier(link);
 334		if (try_to_suspend)
 335			pm_request_idle(link->supplier);
 336	}
 337}
 338
 339static void rpm_put_suppliers(struct device *dev)
 340{
 341	__rpm_put_suppliers(dev, true);
 342}
 343
 344static void rpm_suspend_suppliers(struct device *dev)
 345{
 346	struct device_link *link;
 347	int idx = device_links_read_lock();
 348
 349	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
 350				device_links_read_lock_held())
 351		pm_request_idle(link->supplier);
 352
 353	device_links_read_unlock(idx);
 354}
 355
 356/**
 357 * __rpm_callback - Run a given runtime PM callback for a given device.
 358 * @cb: Runtime PM callback to run.
 359 * @dev: Device to run the callback for.
 360 */
 361static int __rpm_callback(int (*cb)(struct device *), struct device *dev)
 362	__releases(&dev->power.lock) __acquires(&dev->power.lock)
 363{
 364	int retval = 0, idx;
 365	bool use_links = dev->power.links_count > 0;
 366
 367	if (dev->power.irq_safe) {
 368		spin_unlock(&dev->power.lock);
 369	} else {
 370		spin_unlock_irq(&dev->power.lock);
 371
 372		/*
 373		 * Resume suppliers if necessary.
 374		 *
 375		 * The device's runtime PM status cannot change until this
 376		 * routine returns, so it is safe to read the status outside of
 377		 * the lock.
 378		 */
 379		if (use_links && dev->power.runtime_status == RPM_RESUMING) {
 380			idx = device_links_read_lock();
 381
 382			retval = rpm_get_suppliers(dev);
 383			if (retval) {
 384				rpm_put_suppliers(dev);
 385				goto fail;
 386			}
 387
 388			device_links_read_unlock(idx);
 389		}
 390	}
 391
 392	if (cb)
 393		retval = cb(dev);
 394
 395	if (dev->power.irq_safe) {
 396		spin_lock(&dev->power.lock);
 397	} else {
 398		/*
 399		 * If the device is suspending and the callback has returned
 400		 * success, drop the usage counters of the suppliers that have
 401		 * been reference counted on its resume.
 402		 *
 403		 * Do that if resume fails too.
 404		 */
 405		if (use_links &&
 406		    ((dev->power.runtime_status == RPM_SUSPENDING && !retval) ||
 407		    (dev->power.runtime_status == RPM_RESUMING && retval))) {
 408			idx = device_links_read_lock();
 409
 410			__rpm_put_suppliers(dev, false);
 411
 412fail:
 413			device_links_read_unlock(idx);
 414		}
 415
 416		spin_lock_irq(&dev->power.lock);
 417	}
 418
 419	return retval;
 420}
 421
 422/**
 423 * rpm_callback - Run a given runtime PM callback for a given device.
 424 * @cb: Runtime PM callback to run.
 425 * @dev: Device to run the callback for.
 426 */
 427static int rpm_callback(int (*cb)(struct device *), struct device *dev)
 428{
 429	int retval;
 430
 431	if (dev->power.memalloc_noio) {
 432		unsigned int noio_flag;
 433
 434		/*
 435		 * Deadlock might be caused if memory allocation with
 436		 * GFP_KERNEL happens inside runtime_suspend and
 437		 * runtime_resume callbacks of one block device's
 438		 * ancestor or the block device itself. Network
 439		 * device might be thought as part of iSCSI block
 440		 * device, so network device and its ancestor should
 441		 * be marked as memalloc_noio too.
 442		 */
 443		noio_flag = memalloc_noio_save();
 444		retval = __rpm_callback(cb, dev);
 445		memalloc_noio_restore(noio_flag);
 446	} else {
 447		retval = __rpm_callback(cb, dev);
 448	}
 449
 450	dev->power.runtime_error = retval;
 451	return retval != -EACCES ? retval : -EIO;
 452}
 453
 454/**
 455 * rpm_idle - Notify device bus type if the device can be suspended.
 456 * @dev: Device to notify the bus type about.
 457 * @rpmflags: Flag bits.
 458 *
 459 * Check if the device's runtime PM status allows it to be suspended.  If
 460 * another idle notification has been started earlier, return immediately.  If
 461 * the RPM_ASYNC flag is set then queue an idle-notification request; otherwise
 462 * run the ->runtime_idle() callback directly. If the ->runtime_idle callback
 463 * doesn't exist or if it returns 0, call rpm_suspend with the RPM_AUTO flag.
 464 *
 465 * This function must be called under dev->power.lock with interrupts disabled.
 466 */
 467static int rpm_idle(struct device *dev, int rpmflags)
 468{
 469	int (*callback)(struct device *);
 470	int retval;
 471
 472	trace_rpm_idle(dev, rpmflags);
 473	retval = rpm_check_suspend_allowed(dev);
 474	if (retval < 0)
 475		;	/* Conditions are wrong. */
 476
 477	/* Idle notifications are allowed only in the RPM_ACTIVE state. */
 478	else if (dev->power.runtime_status != RPM_ACTIVE)
 479		retval = -EAGAIN;
 480
 481	/*
 482	 * Any pending request other than an idle notification takes
 483	 * precedence over us, except that the timer may be running.
 484	 */
 485	else if (dev->power.request_pending &&
 486	    dev->power.request > RPM_REQ_IDLE)
 487		retval = -EAGAIN;
 488
 489	/* Act as though RPM_NOWAIT is always set. */
 490	else if (dev->power.idle_notification)
 491		retval = -EINPROGRESS;
 492
 493	if (retval)
 494		goto out;
 495
 496	/* Pending requests need to be canceled. */
 497	dev->power.request = RPM_REQ_NONE;
 498
 499	callback = RPM_GET_CALLBACK(dev, runtime_idle);
 500
 501	/* If no callback assume success. */
 502	if (!callback || dev->power.no_callbacks)
 503		goto out;
 504
 505	/* Carry out an asynchronous or a synchronous idle notification. */
 506	if (rpmflags & RPM_ASYNC) {
 507		dev->power.request = RPM_REQ_IDLE;
 508		if (!dev->power.request_pending) {
 509			dev->power.request_pending = true;
 510			queue_work(pm_wq, &dev->power.work);
 511		}
 512		trace_rpm_return_int(dev, _THIS_IP_, 0);
 513		return 0;
 514	}
 515
 516	dev->power.idle_notification = true;
 517
 518	if (dev->power.irq_safe)
 519		spin_unlock(&dev->power.lock);
 520	else
 521		spin_unlock_irq(&dev->power.lock);
 522
 523	retval = callback(dev);
 524
 525	if (dev->power.irq_safe)
 526		spin_lock(&dev->power.lock);
 527	else
 528		spin_lock_irq(&dev->power.lock);
 529
 530	dev->power.idle_notification = false;
 531	wake_up_all(&dev->power.wait_queue);
 532
 533 out:
 534	trace_rpm_return_int(dev, _THIS_IP_, retval);
 535	return retval ? retval : rpm_suspend(dev, rpmflags | RPM_AUTO);
 536}
 537
 538/**
 539 * rpm_suspend - Carry out runtime suspend of given device.
 540 * @dev: Device to suspend.
 541 * @rpmflags: Flag bits.
 542 *
 543 * Check if the device's runtime PM status allows it to be suspended.
 544 * Cancel a pending idle notification, autosuspend or suspend. If
 545 * another suspend has been started earlier, either return immediately
 546 * or wait for it to finish, depending on the RPM_NOWAIT and RPM_ASYNC
 547 * flags. If the RPM_ASYNC flag is set then queue a suspend request;
 548 * otherwise run the ->runtime_suspend() callback directly. When
 549 * ->runtime_suspend succeeded, if a deferred resume was requested while
 550 * the callback was running then carry it out, otherwise send an idle
 551 * notification for its parent (if the suspend succeeded and both
 552 * ignore_children of parent->power and irq_safe of dev->power are not set).
 553 * If ->runtime_suspend failed with -EAGAIN or -EBUSY, and if the RPM_AUTO
 554 * flag is set and the next autosuspend-delay expiration time is in the
 555 * future, schedule another autosuspend attempt.
 556 *
 557 * This function must be called under dev->power.lock with interrupts disabled.
 558 */
 559static int rpm_suspend(struct device *dev, int rpmflags)
 560	__releases(&dev->power.lock) __acquires(&dev->power.lock)
 561{
 562	int (*callback)(struct device *);
 563	struct device *parent = NULL;
 564	int retval;
 565
 566	trace_rpm_suspend(dev, rpmflags);
 567
 568 repeat:
 569	retval = rpm_check_suspend_allowed(dev);
 570	if (retval < 0)
 571		goto out;	/* Conditions are wrong. */
 572
 573	/* Synchronous suspends are not allowed in the RPM_RESUMING state. */
 574	if (dev->power.runtime_status == RPM_RESUMING && !(rpmflags & RPM_ASYNC))
 575		retval = -EAGAIN;
 576
 577	if (retval)
 578		goto out;
 579
 580	/* If the autosuspend_delay time hasn't expired yet, reschedule. */
 581	if ((rpmflags & RPM_AUTO) && dev->power.runtime_status != RPM_SUSPENDING) {
 582		u64 expires = pm_runtime_autosuspend_expiration(dev);
 583
 584		if (expires != 0) {
 585			/* Pending requests need to be canceled. */
 586			dev->power.request = RPM_REQ_NONE;
 587
 588			/*
 589			 * Optimization: If the timer is already running and is
 590			 * set to expire at or before the autosuspend delay,
 591			 * avoid the overhead of resetting it.  Just let it
 592			 * expire; pm_suspend_timer_fn() will take care of the
 593			 * rest.
 594			 */
 595			if (!(dev->power.timer_expires &&
 596			    dev->power.timer_expires <= expires)) {
 597				/*
 598				 * We add a slack of 25% to gather wakeups
 599				 * without sacrificing the granularity.
 600				 */
 601				u64 slack = (u64)READ_ONCE(dev->power.autosuspend_delay) *
 602						    (NSEC_PER_MSEC >> 2);
 603
 604				dev->power.timer_expires = expires;
 605				hrtimer_start_range_ns(&dev->power.suspend_timer,
 606						       ns_to_ktime(expires),
 607						       slack,
 608						       HRTIMER_MODE_ABS);
 609			}
 610			dev->power.timer_autosuspends = 1;
 611			goto out;
 612		}
 613	}
 614
 615	/* Other scheduled or pending requests need to be canceled. */
 616	pm_runtime_cancel_pending(dev);
 617
 618	if (dev->power.runtime_status == RPM_SUSPENDING) {
 619		DEFINE_WAIT(wait);
 620
 621		if (rpmflags & (RPM_ASYNC | RPM_NOWAIT)) {
 622			retval = -EINPROGRESS;
 623			goto out;
 624		}
 625
 626		if (dev->power.irq_safe) {
 627			spin_unlock(&dev->power.lock);
 628
 629			cpu_relax();
 630
 631			spin_lock(&dev->power.lock);
 632			goto repeat;
 633		}
 634
 635		/* Wait for the other suspend running in parallel with us. */
 636		for (;;) {
 637			prepare_to_wait(&dev->power.wait_queue, &wait,
 638					TASK_UNINTERRUPTIBLE);
 639			if (dev->power.runtime_status != RPM_SUSPENDING)
 640				break;
 641
 642			spin_unlock_irq(&dev->power.lock);
 643
 644			schedule();
 645
 646			spin_lock_irq(&dev->power.lock);
 647		}
 648		finish_wait(&dev->power.wait_queue, &wait);
 649		goto repeat;
 650	}
 651
 652	if (dev->power.no_callbacks)
 653		goto no_callback;	/* Assume success. */
 654
 655	/* Carry out an asynchronous or a synchronous suspend. */
 656	if (rpmflags & RPM_ASYNC) {
 657		dev->power.request = (rpmflags & RPM_AUTO) ?
 658		    RPM_REQ_AUTOSUSPEND : RPM_REQ_SUSPEND;
 659		if (!dev->power.request_pending) {
 660			dev->power.request_pending = true;
 661			queue_work(pm_wq, &dev->power.work);
 662		}
 663		goto out;
 664	}
 665
 666	__update_runtime_status(dev, RPM_SUSPENDING);
 667
 668	callback = RPM_GET_CALLBACK(dev, runtime_suspend);
 669
 670	dev_pm_enable_wake_irq_check(dev, true);
 671	retval = rpm_callback(callback, dev);
 672	if (retval)
 673		goto fail;
 674
 675	dev_pm_enable_wake_irq_complete(dev);
 676
 677 no_callback:
 678	__update_runtime_status(dev, RPM_SUSPENDED);
 679	pm_runtime_deactivate_timer(dev);
 680
 681	if (dev->parent) {
 682		parent = dev->parent;
 683		atomic_add_unless(&parent->power.child_count, -1, 0);
 684	}
 685	wake_up_all(&dev->power.wait_queue);
 686
 687	if (dev->power.deferred_resume) {
 688		dev->power.deferred_resume = false;
 689		rpm_resume(dev, 0);
 690		retval = -EAGAIN;
 691		goto out;
 692	}
 693
 694	if (dev->power.irq_safe)
 695		goto out;
 696
 697	/* Maybe the parent is now able to suspend. */
 698	if (parent && !parent->power.ignore_children) {
 699		spin_unlock(&dev->power.lock);
 700
 701		spin_lock(&parent->power.lock);
 702		rpm_idle(parent, RPM_ASYNC);
 703		spin_unlock(&parent->power.lock);
 704
 705		spin_lock(&dev->power.lock);
 706	}
 707	/* Maybe the suppliers are now able to suspend. */
 708	if (dev->power.links_count > 0) {
 709		spin_unlock_irq(&dev->power.lock);
 710
 711		rpm_suspend_suppliers(dev);
 712
 713		spin_lock_irq(&dev->power.lock);
 714	}
 715
 716 out:
 717	trace_rpm_return_int(dev, _THIS_IP_, retval);
 718
 719	return retval;
 720
 721 fail:
 722	dev_pm_disable_wake_irq_check(dev, true);
 723	__update_runtime_status(dev, RPM_ACTIVE);
 724	dev->power.deferred_resume = false;
 725	wake_up_all(&dev->power.wait_queue);
 726
 727	if (retval == -EAGAIN || retval == -EBUSY) {
 728		dev->power.runtime_error = 0;
 729
 730		/*
 731		 * If the callback routine failed an autosuspend, and
 732		 * if the last_busy time has been updated so that there
 733		 * is a new autosuspend expiration time, automatically
 734		 * reschedule another autosuspend.
 735		 */
 736		if ((rpmflags & RPM_AUTO) &&
 737		    pm_runtime_autosuspend_expiration(dev) != 0)
 738			goto repeat;
 739	} else {
 740		pm_runtime_cancel_pending(dev);
 741	}
 742	goto out;
 743}
 744
 745/**
 746 * rpm_resume - Carry out runtime resume of given device.
 747 * @dev: Device to resume.
 748 * @rpmflags: Flag bits.
 749 *
 750 * Check if the device's runtime PM status allows it to be resumed.  Cancel
 751 * any scheduled or pending requests.  If another resume has been started
 752 * earlier, either return immediately or wait for it to finish, depending on the
 753 * RPM_NOWAIT and RPM_ASYNC flags.  Similarly, if there's a suspend running in
 754 * parallel with this function, either tell the other process to resume after
 755 * suspending (deferred_resume) or wait for it to finish.  If the RPM_ASYNC
 756 * flag is set then queue a resume request; otherwise run the
 757 * ->runtime_resume() callback directly.  Queue an idle notification for the
 758 * device if the resume succeeded.
 759 *
 760 * This function must be called under dev->power.lock with interrupts disabled.
 761 */
 762static int rpm_resume(struct device *dev, int rpmflags)
 763	__releases(&dev->power.lock) __acquires(&dev->power.lock)
 764{
 765	int (*callback)(struct device *);
 766	struct device *parent = NULL;
 767	int retval = 0;
 768
 769	trace_rpm_resume(dev, rpmflags);
 770
 771 repeat:
 772	if (dev->power.runtime_error) {
 773		retval = -EINVAL;
 774	} else if (dev->power.disable_depth > 0) {
 775		if (dev->power.runtime_status == RPM_ACTIVE &&
 776		    dev->power.last_status == RPM_ACTIVE)
 777			retval = 1;
 778		else
 779			retval = -EACCES;
 780	}
 781	if (retval)
 782		goto out;
 783
 784	/*
 785	 * Other scheduled or pending requests need to be canceled.  Small
 786	 * optimization: If an autosuspend timer is running, leave it running
 787	 * rather than cancelling it now only to restart it again in the near
 788	 * future.
 789	 */
 790	dev->power.request = RPM_REQ_NONE;
 791	if (!dev->power.timer_autosuspends)
 792		pm_runtime_deactivate_timer(dev);
 793
 794	if (dev->power.runtime_status == RPM_ACTIVE) {
 795		retval = 1;
 796		goto out;
 797	}
 798
 799	if (dev->power.runtime_status == RPM_RESUMING ||
 800	    dev->power.runtime_status == RPM_SUSPENDING) {
 801		DEFINE_WAIT(wait);
 802
 803		if (rpmflags & (RPM_ASYNC | RPM_NOWAIT)) {
 804			if (dev->power.runtime_status == RPM_SUSPENDING) {
 805				dev->power.deferred_resume = true;
 806				if (rpmflags & RPM_NOWAIT)
 807					retval = -EINPROGRESS;
 808			} else {
 809				retval = -EINPROGRESS;
 810			}
 811			goto out;
 812		}
 813
 814		if (dev->power.irq_safe) {
 815			spin_unlock(&dev->power.lock);
 816
 817			cpu_relax();
 818
 819			spin_lock(&dev->power.lock);
 820			goto repeat;
 821		}
 822
 823		/* Wait for the operation carried out in parallel with us. */
 824		for (;;) {
 825			prepare_to_wait(&dev->power.wait_queue, &wait,
 826					TASK_UNINTERRUPTIBLE);
 827			if (dev->power.runtime_status != RPM_RESUMING &&
 828			    dev->power.runtime_status != RPM_SUSPENDING)
 829				break;
 830
 831			spin_unlock_irq(&dev->power.lock);
 832
 833			schedule();
 834
 835			spin_lock_irq(&dev->power.lock);
 836		}
 837		finish_wait(&dev->power.wait_queue, &wait);
 838		goto repeat;
 839	}
 840
 841	/*
 842	 * See if we can skip waking up the parent.  This is safe only if
 843	 * power.no_callbacks is set, because otherwise we don't know whether
 844	 * the resume will actually succeed.
 845	 */
 846	if (dev->power.no_callbacks && !parent && dev->parent) {
 847		spin_lock_nested(&dev->parent->power.lock, SINGLE_DEPTH_NESTING);
 848		if (dev->parent->power.disable_depth > 0 ||
 849		    dev->parent->power.ignore_children ||
 850		    dev->parent->power.runtime_status == RPM_ACTIVE) {
 851			atomic_inc(&dev->parent->power.child_count);
 852			spin_unlock(&dev->parent->power.lock);
 853			retval = 1;
 854			goto no_callback;	/* Assume success. */
 855		}
 856		spin_unlock(&dev->parent->power.lock);
 857	}
 858
 859	/* Carry out an asynchronous or a synchronous resume. */
 860	if (rpmflags & RPM_ASYNC) {
 861		dev->power.request = RPM_REQ_RESUME;
 862		if (!dev->power.request_pending) {
 863			dev->power.request_pending = true;
 864			queue_work(pm_wq, &dev->power.work);
 865		}
 866		retval = 0;
 867		goto out;
 868	}
 869
 870	if (!parent && dev->parent) {
 871		/*
 872		 * Increment the parent's usage counter and resume it if
 873		 * necessary.  Not needed if dev is irq-safe; then the
 874		 * parent is permanently resumed.
 875		 */
 876		parent = dev->parent;
 877		if (dev->power.irq_safe)
 878			goto skip_parent;
 879
 880		spin_unlock(&dev->power.lock);
 881
 882		pm_runtime_get_noresume(parent);
 883
 884		spin_lock(&parent->power.lock);
 885		/*
 886		 * Resume the parent if it has runtime PM enabled and not been
 887		 * set to ignore its children.
 888		 */
 889		if (!parent->power.disable_depth &&
 890		    !parent->power.ignore_children) {
 891			rpm_resume(parent, 0);
 892			if (parent->power.runtime_status != RPM_ACTIVE)
 893				retval = -EBUSY;
 894		}
 895		spin_unlock(&parent->power.lock);
 896
 897		spin_lock(&dev->power.lock);
 898		if (retval)
 899			goto out;
 900
 901		goto repeat;
 902	}
 903 skip_parent:
 904
 905	if (dev->power.no_callbacks)
 906		goto no_callback;	/* Assume success. */
 907
 908	__update_runtime_status(dev, RPM_RESUMING);
 909
 910	callback = RPM_GET_CALLBACK(dev, runtime_resume);
 911
 912	dev_pm_disable_wake_irq_check(dev, false);
 913	retval = rpm_callback(callback, dev);
 914	if (retval) {
 915		__update_runtime_status(dev, RPM_SUSPENDED);
 916		pm_runtime_cancel_pending(dev);
 917		dev_pm_enable_wake_irq_check(dev, false);
 918	} else {
 919 no_callback:
 920		__update_runtime_status(dev, RPM_ACTIVE);
 921		pm_runtime_mark_last_busy(dev);
 922		if (parent)
 923			atomic_inc(&parent->power.child_count);
 924	}
 925	wake_up_all(&dev->power.wait_queue);
 926
 927	if (retval >= 0)
 928		rpm_idle(dev, RPM_ASYNC);
 929
 930 out:
 931	if (parent && !dev->power.irq_safe) {
 932		spin_unlock_irq(&dev->power.lock);
 933
 934		pm_runtime_put(parent);
 935
 936		spin_lock_irq(&dev->power.lock);
 937	}
 938
 939	trace_rpm_return_int(dev, _THIS_IP_, retval);
 940
 941	return retval;
 942}
 943
 944/**
 945 * pm_runtime_work - Universal runtime PM work function.
 946 * @work: Work structure used for scheduling the execution of this function.
 947 *
 948 * Use @work to get the device object the work is to be done for, determine what
 949 * is to be done and execute the appropriate runtime PM function.
 950 */
 951static void pm_runtime_work(struct work_struct *work)
 952{
 953	struct device *dev = container_of(work, struct device, power.work);
 954	enum rpm_request req;
 955
 956	spin_lock_irq(&dev->power.lock);
 957
 958	if (!dev->power.request_pending)
 959		goto out;
 960
 961	req = dev->power.request;
 962	dev->power.request = RPM_REQ_NONE;
 963	dev->power.request_pending = false;
 964
 965	switch (req) {
 966	case RPM_REQ_NONE:
 967		break;
 968	case RPM_REQ_IDLE:
 969		rpm_idle(dev, RPM_NOWAIT);
 970		break;
 971	case RPM_REQ_SUSPEND:
 972		rpm_suspend(dev, RPM_NOWAIT);
 973		break;
 974	case RPM_REQ_AUTOSUSPEND:
 975		rpm_suspend(dev, RPM_NOWAIT | RPM_AUTO);
 976		break;
 977	case RPM_REQ_RESUME:
 978		rpm_resume(dev, RPM_NOWAIT);
 979		break;
 980	}
 981
 982 out:
 983	spin_unlock_irq(&dev->power.lock);
 984}
 985
 986/**
 987 * pm_suspend_timer_fn - Timer function for pm_schedule_suspend().
 988 * @timer: hrtimer used by pm_schedule_suspend().
 989 *
 990 * Check if the time is right and queue a suspend request.
 991 */
 992static enum hrtimer_restart  pm_suspend_timer_fn(struct hrtimer *timer)
 993{
 994	struct device *dev = container_of(timer, struct device, power.suspend_timer);
 995	unsigned long flags;
 996	u64 expires;
 997
 998	spin_lock_irqsave(&dev->power.lock, flags);
 999
1000	expires = dev->power.timer_expires;
1001	/*
1002	 * If 'expires' is after the current time, we've been called
1003	 * too early.
1004	 */
1005	if (expires > 0 && expires < ktime_get_mono_fast_ns()) {
1006		dev->power.timer_expires = 0;
1007		rpm_suspend(dev, dev->power.timer_autosuspends ?
1008		    (RPM_ASYNC | RPM_AUTO) : RPM_ASYNC);
1009	}
1010
1011	spin_unlock_irqrestore(&dev->power.lock, flags);
1012
1013	return HRTIMER_NORESTART;
1014}
1015
1016/**
1017 * pm_schedule_suspend - Set up a timer to submit a suspend request in future.
1018 * @dev: Device to suspend.
1019 * @delay: Time to wait before submitting a suspend request, in milliseconds.
1020 */
1021int pm_schedule_suspend(struct device *dev, unsigned int delay)
1022{
1023	unsigned long flags;
1024	u64 expires;
1025	int retval;
1026
1027	spin_lock_irqsave(&dev->power.lock, flags);
1028
1029	if (!delay) {
1030		retval = rpm_suspend(dev, RPM_ASYNC);
1031		goto out;
1032	}
1033
1034	retval = rpm_check_suspend_allowed(dev);
1035	if (retval)
1036		goto out;
1037
1038	/* Other scheduled or pending requests need to be canceled. */
1039	pm_runtime_cancel_pending(dev);
1040
1041	expires = ktime_get_mono_fast_ns() + (u64)delay * NSEC_PER_MSEC;
1042	dev->power.timer_expires = expires;
1043	dev->power.timer_autosuspends = 0;
1044	hrtimer_start(&dev->power.suspend_timer, expires, HRTIMER_MODE_ABS);
1045
1046 out:
1047	spin_unlock_irqrestore(&dev->power.lock, flags);
1048
1049	return retval;
1050}
1051EXPORT_SYMBOL_GPL(pm_schedule_suspend);
1052
1053static int rpm_drop_usage_count(struct device *dev)
1054{
1055	int ret;
1056
1057	ret = atomic_sub_return(1, &dev->power.usage_count);
1058	if (ret >= 0)
1059		return ret;
1060
1061	/*
1062	 * Because rpm_resume() does not check the usage counter, it will resume
1063	 * the device even if the usage counter is 0 or negative, so it is
1064	 * sufficient to increment the usage counter here to reverse the change
1065	 * made above.
1066	 */
1067	atomic_inc(&dev->power.usage_count);
1068	dev_warn(dev, "Runtime PM usage count underflow!\n");
1069	return -EINVAL;
1070}
1071
1072/**
1073 * __pm_runtime_idle - Entry point for runtime idle operations.
1074 * @dev: Device to send idle notification for.
1075 * @rpmflags: Flag bits.
1076 *
1077 * If the RPM_GET_PUT flag is set, decrement the device's usage count and
1078 * return immediately if it is larger than zero (if it becomes negative, log a
1079 * warning, increment it, and return an error).  Then carry out an idle
1080 * notification, either synchronous or asynchronous.
1081 *
1082 * This routine may be called in atomic context if the RPM_ASYNC flag is set,
1083 * or if pm_runtime_irq_safe() has been called.
1084 */
1085int __pm_runtime_idle(struct device *dev, int rpmflags)
1086{
1087	unsigned long flags;
1088	int retval;
1089
1090	if (rpmflags & RPM_GET_PUT) {
1091		retval = rpm_drop_usage_count(dev);
1092		if (retval < 0) {
1093			return retval;
1094		} else if (retval > 0) {
1095			trace_rpm_usage(dev, rpmflags);
1096			return 0;
1097		}
1098	}
1099
1100	might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);
1101
1102	spin_lock_irqsave(&dev->power.lock, flags);
1103	retval = rpm_idle(dev, rpmflags);
1104	spin_unlock_irqrestore(&dev->power.lock, flags);
1105
1106	return retval;
1107}
1108EXPORT_SYMBOL_GPL(__pm_runtime_idle);
1109
1110/**
1111 * __pm_runtime_suspend - Entry point for runtime put/suspend operations.
1112 * @dev: Device to suspend.
1113 * @rpmflags: Flag bits.
1114 *
1115 * If the RPM_GET_PUT flag is set, decrement the device's usage count and
1116 * return immediately if it is larger than zero (if it becomes negative, log a
1117 * warning, increment it, and return an error).  Then carry out a suspend,
1118 * either synchronous or asynchronous.
1119 *
1120 * This routine may be called in atomic context if the RPM_ASYNC flag is set,
1121 * or if pm_runtime_irq_safe() has been called.
1122 */
1123int __pm_runtime_suspend(struct device *dev, int rpmflags)
1124{
1125	unsigned long flags;
1126	int retval;
1127
1128	if (rpmflags & RPM_GET_PUT) {
1129		retval = rpm_drop_usage_count(dev);
1130		if (retval < 0) {
1131			return retval;
1132		} else if (retval > 0) {
1133			trace_rpm_usage(dev, rpmflags);
1134			return 0;
1135		}
1136	}
1137
1138	might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);
1139
1140	spin_lock_irqsave(&dev->power.lock, flags);
1141	retval = rpm_suspend(dev, rpmflags);
1142	spin_unlock_irqrestore(&dev->power.lock, flags);
1143
1144	return retval;
1145}
1146EXPORT_SYMBOL_GPL(__pm_runtime_suspend);
1147
1148/**
1149 * __pm_runtime_resume - Entry point for runtime resume operations.
1150 * @dev: Device to resume.
1151 * @rpmflags: Flag bits.
1152 *
1153 * If the RPM_GET_PUT flag is set, increment the device's usage count.  Then
1154 * carry out a resume, either synchronous or asynchronous.
1155 *
1156 * This routine may be called in atomic context if the RPM_ASYNC flag is set,
1157 * or if pm_runtime_irq_safe() has been called.
1158 */
1159int __pm_runtime_resume(struct device *dev, int rpmflags)
1160{
1161	unsigned long flags;
1162	int retval;
1163
1164	might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe &&
1165			dev->power.runtime_status != RPM_ACTIVE);
1166
1167	if (rpmflags & RPM_GET_PUT)
1168		atomic_inc(&dev->power.usage_count);
1169
1170	spin_lock_irqsave(&dev->power.lock, flags);
1171	retval = rpm_resume(dev, rpmflags);
1172	spin_unlock_irqrestore(&dev->power.lock, flags);
1173
1174	return retval;
1175}
1176EXPORT_SYMBOL_GPL(__pm_runtime_resume);
1177
1178/**
1179 * pm_runtime_get_if_active - Conditionally bump up device usage counter.
1180 * @dev: Device to handle.
1181 * @ign_usage_count: Whether or not to look at the current usage counter value.
1182 *
1183 * Return -EINVAL if runtime PM is disabled for @dev.
1184 *
1185 * Otherwise, if the runtime PM status of @dev is %RPM_ACTIVE and either
1186 * @ign_usage_count is %true or the runtime PM usage counter of @dev is not
1187 * zero, increment the usage counter of @dev and return 1. Otherwise, return 0
1188 * without changing the usage counter.
1189 *
1190 * If @ign_usage_count is %true, this function can be used to prevent suspending
1191 * the device when its runtime PM status is %RPM_ACTIVE.
1192 *
1193 * If @ign_usage_count is %false, this function can be used to prevent
1194 * suspending the device when both its runtime PM status is %RPM_ACTIVE and its
1195 * runtime PM usage counter is not zero.
1196 *
1197 * The caller is responsible for decrementing the runtime PM usage counter of
1198 * @dev after this function has returned a positive value for it.
1199 */
1200int pm_runtime_get_if_active(struct device *dev, bool ign_usage_count)
1201{
1202	unsigned long flags;
1203	int retval;
1204
1205	spin_lock_irqsave(&dev->power.lock, flags);
1206	if (dev->power.disable_depth > 0) {
1207		retval = -EINVAL;
1208	} else if (dev->power.runtime_status != RPM_ACTIVE) {
1209		retval = 0;
1210	} else if (ign_usage_count) {
1211		retval = 1;
1212		atomic_inc(&dev->power.usage_count);
1213	} else {
1214		retval = atomic_inc_not_zero(&dev->power.usage_count);
1215	}
1216	trace_rpm_usage(dev, 0);
1217	spin_unlock_irqrestore(&dev->power.lock, flags);
1218
1219	return retval;
1220}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1221EXPORT_SYMBOL_GPL(pm_runtime_get_if_active);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1222
1223/**
1224 * __pm_runtime_set_status - Set runtime PM status of a device.
1225 * @dev: Device to handle.
1226 * @status: New runtime PM status of the device.
1227 *
1228 * If runtime PM of the device is disabled or its power.runtime_error field is
1229 * different from zero, the status may be changed either to RPM_ACTIVE, or to
1230 * RPM_SUSPENDED, as long as that reflects the actual state of the device.
1231 * However, if the device has a parent and the parent is not active, and the
1232 * parent's power.ignore_children flag is unset, the device's status cannot be
1233 * set to RPM_ACTIVE, so -EBUSY is returned in that case.
1234 *
1235 * If successful, __pm_runtime_set_status() clears the power.runtime_error field
1236 * and the device parent's counter of unsuspended children is modified to
1237 * reflect the new status.  If the new status is RPM_SUSPENDED, an idle
1238 * notification request for the parent is submitted.
1239 *
1240 * If @dev has any suppliers (as reflected by device links to them), and @status
1241 * is RPM_ACTIVE, they will be activated upfront and if the activation of one
1242 * of them fails, the status of @dev will be changed to RPM_SUSPENDED (instead
1243 * of the @status value) and the suppliers will be deacticated on exit.  The
1244 * error returned by the failing supplier activation will be returned in that
1245 * case.
1246 */
1247int __pm_runtime_set_status(struct device *dev, unsigned int status)
1248{
1249	struct device *parent = dev->parent;
1250	bool notify_parent = false;
1251	unsigned long flags;
1252	int error = 0;
1253
1254	if (status != RPM_ACTIVE && status != RPM_SUSPENDED)
1255		return -EINVAL;
1256
1257	spin_lock_irqsave(&dev->power.lock, flags);
1258
1259	/*
1260	 * Prevent PM-runtime from being enabled for the device or return an
1261	 * error if it is enabled already and working.
1262	 */
1263	if (dev->power.runtime_error || dev->power.disable_depth)
1264		dev->power.disable_depth++;
1265	else
1266		error = -EAGAIN;
1267
1268	spin_unlock_irqrestore(&dev->power.lock, flags);
1269
1270	if (error)
1271		return error;
1272
1273	/*
1274	 * If the new status is RPM_ACTIVE, the suppliers can be activated
1275	 * upfront regardless of the current status, because next time
1276	 * rpm_put_suppliers() runs, the rpm_active refcounts of the links
1277	 * involved will be dropped down to one anyway.
1278	 */
1279	if (status == RPM_ACTIVE) {
1280		int idx = device_links_read_lock();
1281
1282		error = rpm_get_suppliers(dev);
1283		if (error)
1284			status = RPM_SUSPENDED;
1285
1286		device_links_read_unlock(idx);
1287	}
1288
1289	spin_lock_irqsave(&dev->power.lock, flags);
1290
1291	if (dev->power.runtime_status == status || !parent)
1292		goto out_set;
1293
1294	if (status == RPM_SUSPENDED) {
1295		atomic_add_unless(&parent->power.child_count, -1, 0);
1296		notify_parent = !parent->power.ignore_children;
1297	} else {
1298		spin_lock_nested(&parent->power.lock, SINGLE_DEPTH_NESTING);
1299
1300		/*
1301		 * It is invalid to put an active child under a parent that is
1302		 * not active, has runtime PM enabled and the
1303		 * 'power.ignore_children' flag unset.
1304		 */
1305		if (!parent->power.disable_depth &&
1306		    !parent->power.ignore_children &&
1307		    parent->power.runtime_status != RPM_ACTIVE) {
1308			dev_err(dev, "runtime PM trying to activate child device %s but parent (%s) is not active\n",
1309				dev_name(dev),
1310				dev_name(parent));
1311			error = -EBUSY;
1312		} else if (dev->power.runtime_status == RPM_SUSPENDED) {
1313			atomic_inc(&parent->power.child_count);
1314		}
1315
1316		spin_unlock(&parent->power.lock);
1317
1318		if (error) {
1319			status = RPM_SUSPENDED;
1320			goto out;
1321		}
1322	}
1323
1324 out_set:
1325	__update_runtime_status(dev, status);
1326	if (!error)
1327		dev->power.runtime_error = 0;
1328
1329 out:
1330	spin_unlock_irqrestore(&dev->power.lock, flags);
1331
1332	if (notify_parent)
1333		pm_request_idle(parent);
1334
1335	if (status == RPM_SUSPENDED) {
1336		int idx = device_links_read_lock();
1337
1338		rpm_put_suppliers(dev);
1339
1340		device_links_read_unlock(idx);
1341	}
1342
1343	pm_runtime_enable(dev);
1344
1345	return error;
1346}
1347EXPORT_SYMBOL_GPL(__pm_runtime_set_status);
1348
1349/**
1350 * __pm_runtime_barrier - Cancel pending requests and wait for completions.
1351 * @dev: Device to handle.
1352 *
1353 * Flush all pending requests for the device from pm_wq and wait for all
1354 * runtime PM operations involving the device in progress to complete.
1355 *
1356 * Should be called under dev->power.lock with interrupts disabled.
1357 */
1358static void __pm_runtime_barrier(struct device *dev)
1359{
1360	pm_runtime_deactivate_timer(dev);
1361
1362	if (dev->power.request_pending) {
1363		dev->power.request = RPM_REQ_NONE;
1364		spin_unlock_irq(&dev->power.lock);
1365
1366		cancel_work_sync(&dev->power.work);
1367
1368		spin_lock_irq(&dev->power.lock);
1369		dev->power.request_pending = false;
1370	}
1371
1372	if (dev->power.runtime_status == RPM_SUSPENDING ||
1373	    dev->power.runtime_status == RPM_RESUMING ||
1374	    dev->power.idle_notification) {
1375		DEFINE_WAIT(wait);
1376
1377		/* Suspend, wake-up or idle notification in progress. */
1378		for (;;) {
1379			prepare_to_wait(&dev->power.wait_queue, &wait,
1380					TASK_UNINTERRUPTIBLE);
1381			if (dev->power.runtime_status != RPM_SUSPENDING
1382			    && dev->power.runtime_status != RPM_RESUMING
1383			    && !dev->power.idle_notification)
1384				break;
1385			spin_unlock_irq(&dev->power.lock);
1386
1387			schedule();
1388
1389			spin_lock_irq(&dev->power.lock);
1390		}
1391		finish_wait(&dev->power.wait_queue, &wait);
1392	}
1393}
1394
1395/**
1396 * pm_runtime_barrier - Flush pending requests and wait for completions.
1397 * @dev: Device to handle.
1398 *
1399 * Prevent the device from being suspended by incrementing its usage counter and
1400 * if there's a pending resume request for the device, wake the device up.
1401 * Next, make sure that all pending requests for the device have been flushed
1402 * from pm_wq and wait for all runtime PM operations involving the device in
1403 * progress to complete.
1404 *
1405 * Return value:
1406 * 1, if there was a resume request pending and the device had to be woken up,
1407 * 0, otherwise
1408 */
1409int pm_runtime_barrier(struct device *dev)
1410{
1411	int retval = 0;
1412
1413	pm_runtime_get_noresume(dev);
1414	spin_lock_irq(&dev->power.lock);
1415
1416	if (dev->power.request_pending
1417	    && dev->power.request == RPM_REQ_RESUME) {
1418		rpm_resume(dev, 0);
1419		retval = 1;
1420	}
1421
1422	__pm_runtime_barrier(dev);
1423
1424	spin_unlock_irq(&dev->power.lock);
1425	pm_runtime_put_noidle(dev);
1426
1427	return retval;
1428}
1429EXPORT_SYMBOL_GPL(pm_runtime_barrier);
1430
1431/**
1432 * __pm_runtime_disable - Disable runtime PM of a device.
1433 * @dev: Device to handle.
1434 * @check_resume: If set, check if there's a resume request for the device.
1435 *
1436 * Increment power.disable_depth for the device and if it was zero previously,
1437 * cancel all pending runtime PM requests for the device and wait for all
1438 * operations in progress to complete.  The device can be either active or
1439 * suspended after its runtime PM has been disabled.
1440 *
1441 * If @check_resume is set and there's a resume request pending when
1442 * __pm_runtime_disable() is called and power.disable_depth is zero, the
1443 * function will wake up the device before disabling its runtime PM.
1444 */
1445void __pm_runtime_disable(struct device *dev, bool check_resume)
1446{
1447	spin_lock_irq(&dev->power.lock);
1448
1449	if (dev->power.disable_depth > 0) {
1450		dev->power.disable_depth++;
1451		goto out;
1452	}
1453
1454	/*
1455	 * Wake up the device if there's a resume request pending, because that
1456	 * means there probably is some I/O to process and disabling runtime PM
1457	 * shouldn't prevent the device from processing the I/O.
1458	 */
1459	if (check_resume && dev->power.request_pending &&
1460	    dev->power.request == RPM_REQ_RESUME) {
1461		/*
1462		 * Prevent suspends and idle notifications from being carried
1463		 * out after we have woken up the device.
1464		 */
1465		pm_runtime_get_noresume(dev);
1466
1467		rpm_resume(dev, 0);
1468
1469		pm_runtime_put_noidle(dev);
1470	}
1471
1472	/* Update time accounting before disabling PM-runtime. */
1473	update_pm_runtime_accounting(dev);
1474
1475	if (!dev->power.disable_depth++) {
1476		__pm_runtime_barrier(dev);
1477		dev->power.last_status = dev->power.runtime_status;
1478	}
1479
1480 out:
1481	spin_unlock_irq(&dev->power.lock);
1482}
1483EXPORT_SYMBOL_GPL(__pm_runtime_disable);
1484
1485/**
1486 * pm_runtime_enable - Enable runtime PM of a device.
1487 * @dev: Device to handle.
1488 */
1489void pm_runtime_enable(struct device *dev)
1490{
1491	unsigned long flags;
1492
1493	spin_lock_irqsave(&dev->power.lock, flags);
1494
1495	if (!dev->power.disable_depth) {
1496		dev_warn(dev, "Unbalanced %s!\n", __func__);
1497		goto out;
1498	}
1499
1500	if (--dev->power.disable_depth > 0)
1501		goto out;
1502
1503	dev->power.last_status = RPM_INVALID;
1504	dev->power.accounting_timestamp = ktime_get_mono_fast_ns();
1505
1506	if (dev->power.runtime_status == RPM_SUSPENDED &&
1507	    !dev->power.ignore_children &&
1508	    atomic_read(&dev->power.child_count) > 0)
1509		dev_warn(dev, "Enabling runtime PM for inactive device with active children\n");
1510
1511out:
1512	spin_unlock_irqrestore(&dev->power.lock, flags);
1513}
1514EXPORT_SYMBOL_GPL(pm_runtime_enable);
1515
1516static void pm_runtime_disable_action(void *data)
1517{
1518	pm_runtime_dont_use_autosuspend(data);
1519	pm_runtime_disable(data);
1520}
1521
1522/**
1523 * devm_pm_runtime_enable - devres-enabled version of pm_runtime_enable.
1524 *
1525 * NOTE: this will also handle calling pm_runtime_dont_use_autosuspend() for
1526 * you at driver exit time if needed.
1527 *
1528 * @dev: Device to handle.
1529 */
1530int devm_pm_runtime_enable(struct device *dev)
1531{
1532	pm_runtime_enable(dev);
1533
1534	return devm_add_action_or_reset(dev, pm_runtime_disable_action, dev);
1535}
1536EXPORT_SYMBOL_GPL(devm_pm_runtime_enable);
1537
1538/**
1539 * pm_runtime_forbid - Block runtime PM of a device.
1540 * @dev: Device to handle.
1541 *
1542 * Increase the device's usage count and clear its power.runtime_auto flag,
1543 * so that it cannot be suspended at run time until pm_runtime_allow() is called
1544 * for it.
1545 */
1546void pm_runtime_forbid(struct device *dev)
1547{
1548	spin_lock_irq(&dev->power.lock);
1549	if (!dev->power.runtime_auto)
1550		goto out;
1551
1552	dev->power.runtime_auto = false;
1553	atomic_inc(&dev->power.usage_count);
1554	rpm_resume(dev, 0);
1555
1556 out:
1557	spin_unlock_irq(&dev->power.lock);
1558}
1559EXPORT_SYMBOL_GPL(pm_runtime_forbid);
1560
1561/**
1562 * pm_runtime_allow - Unblock runtime PM of a device.
1563 * @dev: Device to handle.
1564 *
1565 * Decrease the device's usage count and set its power.runtime_auto flag.
1566 */
1567void pm_runtime_allow(struct device *dev)
1568{
1569	int ret;
1570
1571	spin_lock_irq(&dev->power.lock);
1572	if (dev->power.runtime_auto)
1573		goto out;
1574
1575	dev->power.runtime_auto = true;
1576	ret = rpm_drop_usage_count(dev);
1577	if (ret == 0)
1578		rpm_idle(dev, RPM_AUTO | RPM_ASYNC);
1579	else if (ret > 0)
1580		trace_rpm_usage(dev, RPM_AUTO | RPM_ASYNC);
1581
1582 out:
1583	spin_unlock_irq(&dev->power.lock);
1584}
1585EXPORT_SYMBOL_GPL(pm_runtime_allow);
1586
1587/**
1588 * pm_runtime_no_callbacks - Ignore runtime PM callbacks for a device.
1589 * @dev: Device to handle.
1590 *
1591 * Set the power.no_callbacks flag, which tells the PM core that this
1592 * device is power-managed through its parent and has no runtime PM
1593 * callbacks of its own.  The runtime sysfs attributes will be removed.
1594 */
1595void pm_runtime_no_callbacks(struct device *dev)
1596{
1597	spin_lock_irq(&dev->power.lock);
1598	dev->power.no_callbacks = 1;
1599	spin_unlock_irq(&dev->power.lock);
1600	if (device_is_registered(dev))
1601		rpm_sysfs_remove(dev);
1602}
1603EXPORT_SYMBOL_GPL(pm_runtime_no_callbacks);
1604
1605/**
1606 * pm_runtime_irq_safe - Leave interrupts disabled during callbacks.
1607 * @dev: Device to handle
1608 *
1609 * Set the power.irq_safe flag, which tells the PM core that the
1610 * ->runtime_suspend() and ->runtime_resume() callbacks for this device should
1611 * always be invoked with the spinlock held and interrupts disabled.  It also
1612 * causes the parent's usage counter to be permanently incremented, preventing
1613 * the parent from runtime suspending -- otherwise an irq-safe child might have
1614 * to wait for a non-irq-safe parent.
1615 */
1616void pm_runtime_irq_safe(struct device *dev)
1617{
1618	if (dev->parent)
1619		pm_runtime_get_sync(dev->parent);
1620
1621	spin_lock_irq(&dev->power.lock);
1622	dev->power.irq_safe = 1;
1623	spin_unlock_irq(&dev->power.lock);
1624}
1625EXPORT_SYMBOL_GPL(pm_runtime_irq_safe);
1626
1627/**
1628 * update_autosuspend - Handle a change to a device's autosuspend settings.
1629 * @dev: Device to handle.
1630 * @old_delay: The former autosuspend_delay value.
1631 * @old_use: The former use_autosuspend value.
1632 *
1633 * Prevent runtime suspend if the new delay is negative and use_autosuspend is
1634 * set; otherwise allow it.  Send an idle notification if suspends are allowed.
1635 *
1636 * This function must be called under dev->power.lock with interrupts disabled.
1637 */
1638static void update_autosuspend(struct device *dev, int old_delay, int old_use)
1639{
1640	int delay = dev->power.autosuspend_delay;
1641
1642	/* Should runtime suspend be prevented now? */
1643	if (dev->power.use_autosuspend && delay < 0) {
1644
1645		/* If it used to be allowed then prevent it. */
1646		if (!old_use || old_delay >= 0) {
1647			atomic_inc(&dev->power.usage_count);
1648			rpm_resume(dev, 0);
1649		} else {
1650			trace_rpm_usage(dev, 0);
1651		}
1652	}
1653
1654	/* Runtime suspend should be allowed now. */
1655	else {
1656
1657		/* If it used to be prevented then allow it. */
1658		if (old_use && old_delay < 0)
1659			atomic_dec(&dev->power.usage_count);
1660
1661		/* Maybe we can autosuspend now. */
1662		rpm_idle(dev, RPM_AUTO);
1663	}
1664}
1665
1666/**
1667 * pm_runtime_set_autosuspend_delay - Set a device's autosuspend_delay value.
1668 * @dev: Device to handle.
1669 * @delay: Value of the new delay in milliseconds.
1670 *
1671 * Set the device's power.autosuspend_delay value.  If it changes to negative
1672 * and the power.use_autosuspend flag is set, prevent runtime suspends.  If it
1673 * changes the other way, allow runtime suspends.
1674 */
1675void pm_runtime_set_autosuspend_delay(struct device *dev, int delay)
1676{
1677	int old_delay, old_use;
1678
1679	spin_lock_irq(&dev->power.lock);
1680	old_delay = dev->power.autosuspend_delay;
1681	old_use = dev->power.use_autosuspend;
1682	dev->power.autosuspend_delay = delay;
1683	update_autosuspend(dev, old_delay, old_use);
1684	spin_unlock_irq(&dev->power.lock);
1685}
1686EXPORT_SYMBOL_GPL(pm_runtime_set_autosuspend_delay);
1687
1688/**
1689 * __pm_runtime_use_autosuspend - Set a device's use_autosuspend flag.
1690 * @dev: Device to handle.
1691 * @use: New value for use_autosuspend.
1692 *
1693 * Set the device's power.use_autosuspend flag, and allow or prevent runtime
1694 * suspends as needed.
1695 */
1696void __pm_runtime_use_autosuspend(struct device *dev, bool use)
1697{
1698	int old_delay, old_use;
1699
1700	spin_lock_irq(&dev->power.lock);
1701	old_delay = dev->power.autosuspend_delay;
1702	old_use = dev->power.use_autosuspend;
1703	dev->power.use_autosuspend = use;
1704	update_autosuspend(dev, old_delay, old_use);
1705	spin_unlock_irq(&dev->power.lock);
1706}
1707EXPORT_SYMBOL_GPL(__pm_runtime_use_autosuspend);
1708
1709/**
1710 * pm_runtime_init - Initialize runtime PM fields in given device object.
1711 * @dev: Device object to initialize.
1712 */
1713void pm_runtime_init(struct device *dev)
1714{
1715	dev->power.runtime_status = RPM_SUSPENDED;
1716	dev->power.last_status = RPM_INVALID;
1717	dev->power.idle_notification = false;
1718
1719	dev->power.disable_depth = 1;
1720	atomic_set(&dev->power.usage_count, 0);
1721
1722	dev->power.runtime_error = 0;
1723
1724	atomic_set(&dev->power.child_count, 0);
1725	pm_suspend_ignore_children(dev, false);
1726	dev->power.runtime_auto = true;
1727
1728	dev->power.request_pending = false;
1729	dev->power.request = RPM_REQ_NONE;
1730	dev->power.deferred_resume = false;
1731	dev->power.needs_force_resume = 0;
1732	INIT_WORK(&dev->power.work, pm_runtime_work);
1733
1734	dev->power.timer_expires = 0;
1735	hrtimer_init(&dev->power.suspend_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
1736	dev->power.suspend_timer.function = pm_suspend_timer_fn;
1737
1738	init_waitqueue_head(&dev->power.wait_queue);
1739}
1740
1741/**
1742 * pm_runtime_reinit - Re-initialize runtime PM fields in given device object.
1743 * @dev: Device object to re-initialize.
1744 */
1745void pm_runtime_reinit(struct device *dev)
1746{
1747	if (!pm_runtime_enabled(dev)) {
1748		if (dev->power.runtime_status == RPM_ACTIVE)
1749			pm_runtime_set_suspended(dev);
1750		if (dev->power.irq_safe) {
1751			spin_lock_irq(&dev->power.lock);
1752			dev->power.irq_safe = 0;
1753			spin_unlock_irq(&dev->power.lock);
1754			if (dev->parent)
1755				pm_runtime_put(dev->parent);
1756		}
1757	}
1758}
1759
1760/**
1761 * pm_runtime_remove - Prepare for removing a device from device hierarchy.
1762 * @dev: Device object being removed from device hierarchy.
1763 */
1764void pm_runtime_remove(struct device *dev)
1765{
1766	__pm_runtime_disable(dev, false);
1767	pm_runtime_reinit(dev);
1768}
1769
1770/**
1771 * pm_runtime_get_suppliers - Resume and reference-count supplier devices.
1772 * @dev: Consumer device.
1773 */
1774void pm_runtime_get_suppliers(struct device *dev)
1775{
1776	struct device_link *link;
1777	int idx;
1778
1779	idx = device_links_read_lock();
1780
1781	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
1782				device_links_read_lock_held())
1783		if (link->flags & DL_FLAG_PM_RUNTIME) {
1784			link->supplier_preactivated = true;
1785			pm_runtime_get_sync(link->supplier);
1786		}
1787
1788	device_links_read_unlock(idx);
1789}
1790
1791/**
1792 * pm_runtime_put_suppliers - Drop references to supplier devices.
1793 * @dev: Consumer device.
1794 */
1795void pm_runtime_put_suppliers(struct device *dev)
1796{
1797	struct device_link *link;
1798	int idx;
1799
1800	idx = device_links_read_lock();
1801
1802	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
1803				device_links_read_lock_held())
1804		if (link->supplier_preactivated) {
1805			link->supplier_preactivated = false;
1806			pm_runtime_put(link->supplier);
1807		}
1808
1809	device_links_read_unlock(idx);
1810}
1811
1812void pm_runtime_new_link(struct device *dev)
1813{
1814	spin_lock_irq(&dev->power.lock);
1815	dev->power.links_count++;
1816	spin_unlock_irq(&dev->power.lock);
1817}
1818
1819static void pm_runtime_drop_link_count(struct device *dev)
1820{
1821	spin_lock_irq(&dev->power.lock);
1822	WARN_ON(dev->power.links_count == 0);
1823	dev->power.links_count--;
1824	spin_unlock_irq(&dev->power.lock);
1825}
1826
1827/**
1828 * pm_runtime_drop_link - Prepare for device link removal.
1829 * @link: Device link going away.
1830 *
1831 * Drop the link count of the consumer end of @link and decrement the supplier
1832 * device's runtime PM usage counter as many times as needed to drop all of the
1833 * PM runtime reference to it from the consumer.
1834 */
1835void pm_runtime_drop_link(struct device_link *link)
1836{
1837	if (!(link->flags & DL_FLAG_PM_RUNTIME))
1838		return;
1839
1840	pm_runtime_drop_link_count(link->consumer);
1841	pm_runtime_release_supplier(link);
1842	pm_request_idle(link->supplier);
1843}
1844
1845static bool pm_runtime_need_not_resume(struct device *dev)
1846{
1847	return atomic_read(&dev->power.usage_count) <= 1 &&
1848		(atomic_read(&dev->power.child_count) == 0 ||
1849		 dev->power.ignore_children);
1850}
1851
1852/**
1853 * pm_runtime_force_suspend - Force a device into suspend state if needed.
1854 * @dev: Device to suspend.
1855 *
1856 * Disable runtime PM so we safely can check the device's runtime PM status and
1857 * if it is active, invoke its ->runtime_suspend callback to suspend it and
1858 * change its runtime PM status field to RPM_SUSPENDED.  Also, if the device's
1859 * usage and children counters don't indicate that the device was in use before
1860 * the system-wide transition under way, decrement its parent's children counter
1861 * (if there is a parent).  Keep runtime PM disabled to preserve the state
1862 * unless we encounter errors.
1863 *
1864 * Typically this function may be invoked from a system suspend callback to make
1865 * sure the device is put into low power state and it should only be used during
1866 * system-wide PM transitions to sleep states.  It assumes that the analogous
1867 * pm_runtime_force_resume() will be used to resume the device.
1868 *
1869 * Do not use with DPM_FLAG_SMART_SUSPEND as this can lead to an inconsistent
1870 * state where this function has called the ->runtime_suspend callback but the
1871 * PM core marks the driver as runtime active.
1872 */
1873int pm_runtime_force_suspend(struct device *dev)
1874{
1875	int (*callback)(struct device *);
1876	int ret;
1877
1878	pm_runtime_disable(dev);
1879	if (pm_runtime_status_suspended(dev))
1880		return 0;
1881
1882	callback = RPM_GET_CALLBACK(dev, runtime_suspend);
1883
1884	dev_pm_enable_wake_irq_check(dev, true);
1885	ret = callback ? callback(dev) : 0;
1886	if (ret)
1887		goto err;
1888
1889	dev_pm_enable_wake_irq_complete(dev);
1890
1891	/*
1892	 * If the device can stay in suspend after the system-wide transition
1893	 * to the working state that will follow, drop the children counter of
1894	 * its parent, but set its status to RPM_SUSPENDED anyway in case this
1895	 * function will be called again for it in the meantime.
1896	 */
1897	if (pm_runtime_need_not_resume(dev)) {
1898		pm_runtime_set_suspended(dev);
1899	} else {
1900		__update_runtime_status(dev, RPM_SUSPENDED);
1901		dev->power.needs_force_resume = 1;
1902	}
1903
1904	return 0;
1905
1906err:
1907	dev_pm_disable_wake_irq_check(dev, true);
1908	pm_runtime_enable(dev);
1909	return ret;
1910}
1911EXPORT_SYMBOL_GPL(pm_runtime_force_suspend);
1912
1913/**
1914 * pm_runtime_force_resume - Force a device into resume state if needed.
1915 * @dev: Device to resume.
1916 *
1917 * Prior invoking this function we expect the user to have brought the device
1918 * into low power state by a call to pm_runtime_force_suspend(). Here we reverse
1919 * those actions and bring the device into full power, if it is expected to be
1920 * used on system resume.  In the other case, we defer the resume to be managed
1921 * via runtime PM.
1922 *
1923 * Typically this function may be invoked from a system resume callback.
1924 */
1925int pm_runtime_force_resume(struct device *dev)
1926{
1927	int (*callback)(struct device *);
1928	int ret = 0;
1929
1930	if (!pm_runtime_status_suspended(dev) || !dev->power.needs_force_resume)
1931		goto out;
1932
1933	/*
1934	 * The value of the parent's children counter is correct already, so
1935	 * just update the status of the device.
1936	 */
1937	__update_runtime_status(dev, RPM_ACTIVE);
1938
1939	callback = RPM_GET_CALLBACK(dev, runtime_resume);
1940
1941	dev_pm_disable_wake_irq_check(dev, false);
1942	ret = callback ? callback(dev) : 0;
1943	if (ret) {
1944		pm_runtime_set_suspended(dev);
1945		dev_pm_enable_wake_irq_check(dev, false);
1946		goto out;
1947	}
1948
1949	pm_runtime_mark_last_busy(dev);
1950out:
1951	dev->power.needs_force_resume = 0;
1952	pm_runtime_enable(dev);
1953	return ret;
1954}
1955EXPORT_SYMBOL_GPL(pm_runtime_force_resume);