kernel/power/suspend.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * kernel/power/suspend.c - Suspend to RAM and standby functionality.
  *
  * Copyright (c) 2003 Patrick Mochel
  * Copyright (c) 2003 Open Source Development Lab
  * Copyright (c) 2009 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
  */

 #define pr_fmt(fmt) "PM: " fmt

 #include <linux/string.h>
 #include <linux/delay.h>
 #include <linux/errno.h>
 #include <linux/init.h>
 #include <linux/console.h>
 #include <linux/cpu.h>
 #include <linux/cpuidle.h>
 #include <linux/gfp.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
 #include <linux/list.h>
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/export.h>
 #include <linux/suspend.h>
 #include <linux/syscore_ops.h>
 #include <linux/swait.h>
 #include <linux/ftrace.h>
 #include <trace/events/power.h>
 #include <linux/compiler.h>
 #include <linux/moduleparam.h>

 #include "power.h"

 const char * const pm_labels[] = {
 	[PM_SUSPEND_TO_IDLE] = "freeze",
 	[PM_SUSPEND_STANDBY] = "standby",
 	[PM_SUSPEND_MEM] = "mem",
 };
 const char *pm_states[PM_SUSPEND_MAX];
 static const char * const mem_sleep_labels[] = {
 	[PM_SUSPEND_TO_IDLE] = "s2idle",
 	[PM_SUSPEND_STANDBY] = "shallow",
 	[PM_SUSPEND_MEM] = "deep",
 };
 const char *mem_sleep_states[PM_SUSPEND_MAX];

 suspend_state_t mem_sleep_current = PM_SUSPEND_TO_IDLE;
 suspend_state_t mem_sleep_default = PM_SUSPEND_MAX;
 suspend_state_t pm_suspend_target_state;
 EXPORT_SYMBOL_GPL(pm_suspend_target_state);

 unsigned int pm_suspend_global_flags;
 EXPORT_SYMBOL_GPL(pm_suspend_global_flags);

 static const struct platform_suspend_ops *suspend_ops;
 static const struct platform_s2idle_ops *s2idle_ops;
 static DECLARE_SWAIT_QUEUE_HEAD(s2idle_wait_head);

 enum s2idle_states __read_mostly s2idle_state;
 static DEFINE_RAW_SPINLOCK(s2idle_lock);

 /**
  * pm_suspend_default_s2idle - Check if suspend-to-idle is the default suspend.
  *
  * Return 'true' if suspend-to-idle has been selected as the default system
  * suspend method.
  */
 bool pm_suspend_default_s2idle(void)
 {
 	return mem_sleep_current == PM_SUSPEND_TO_IDLE;
 }
 EXPORT_SYMBOL_GPL(pm_suspend_default_s2idle);

 void s2idle_set_ops(const struct platform_s2idle_ops *ops)
 {
 	lock_system_sleep();
 	s2idle_ops = ops;
 	unlock_system_sleep();
 }

 static void s2idle_begin(void)
 {
 	s2idle_state = S2IDLE_STATE_NONE;
 }

 static void s2idle_enter(void)
 {
 	trace_suspend_resume(TPS("machine_suspend"), PM_SUSPEND_TO_IDLE, true);

 	raw_spin_lock_irq(&s2idle_lock);
 	if (pm_wakeup_pending())
 		goto out;

 	s2idle_state = S2IDLE_STATE_ENTER;
 	raw_spin_unlock_irq(&s2idle_lock);

 	get_online_cpus();
 	cpuidle_resume();

 	/* Push all the CPUs into the idle loop. */
 	wake_up_all_idle_cpus();
 	/* Make the current CPU wait so it can enter the idle loop too. */
 	swait_event_exclusive(s2idle_wait_head,
 		    s2idle_state == S2IDLE_STATE_WAKE);

 	cpuidle_pause();
 	put_online_cpus();

 	raw_spin_lock_irq(&s2idle_lock);

  out:
 	s2idle_state = S2IDLE_STATE_NONE;
 	raw_spin_unlock_irq(&s2idle_lock);

 	trace_suspend_resume(TPS("machine_suspend"), PM_SUSPEND_TO_IDLE, false);
 }

 static void s2idle_loop(void)
 {
 	pm_pr_dbg("suspend-to-idle\n");

 	/*
 	 * Suspend-to-idle equals:
 	 * frozen processes + suspended devices + idle processors.
 	 * Thus s2idle_enter() should be called right after all devices have
 	 * been suspended.
 	 *
 	 * Wakeups during the noirq suspend of devices may be spurious, so try
 	 * to avoid them upfront.
 	 */
 	for (;;) {
 		if (s2idle_ops && s2idle_ops->wake) {
 			if (s2idle_ops->wake())
 				break;
 		} else if (pm_wakeup_pending()) {
 			break;
 		}

 		pm_wakeup_clear(false);

 		s2idle_enter();
 	}

 	pm_pr_dbg("resume from suspend-to-idle\n");
 }

 void s2idle_wake(void)
 {
 	unsigned long flags;

 	raw_spin_lock_irqsave(&s2idle_lock, flags);
 	if (s2idle_state > S2IDLE_STATE_NONE) {
 		s2idle_state = S2IDLE_STATE_WAKE;
 		swake_up_one(&s2idle_wait_head);
 	}
 	raw_spin_unlock_irqrestore(&s2idle_lock, flags);
 }
 EXPORT_SYMBOL_GPL(s2idle_wake);

 static bool valid_state(suspend_state_t state)
 {
 	/*
 	 * PM_SUSPEND_STANDBY and PM_SUSPEND_MEM states need low level
 	 * support and need to be valid to the low level
 	 * implementation, no valid callback implies that none are valid.
 	 */
 	return suspend_ops && suspend_ops->valid && suspend_ops->valid(state);
 }

 void __init pm_states_init(void)
 {
 	/* "mem" and "freeze" are always present in /sys/power/state. */
 	pm_states[PM_SUSPEND_MEM] = pm_labels[PM_SUSPEND_MEM];
 	pm_states[PM_SUSPEND_TO_IDLE] = pm_labels[PM_SUSPEND_TO_IDLE];
 	/*
 	 * Suspend-to-idle should be supported even without any suspend_ops,
 	 * initialize mem_sleep_states[] accordingly here.
 	 */
 	mem_sleep_states[PM_SUSPEND_TO_IDLE] = mem_sleep_labels[PM_SUSPEND_TO_IDLE];
 }

 static int __init mem_sleep_default_setup(char *str)
 {
 	suspend_state_t state;

 	for (state = PM_SUSPEND_TO_IDLE; state <= PM_SUSPEND_MEM; state++)
 		if (mem_sleep_labels[state] &&
 		    !strcmp(str, mem_sleep_labels[state])) {
 			mem_sleep_default = state;
 			break;
 		}

 	return 1;
 }
 __setup("mem_sleep_default=", mem_sleep_default_setup);

 /**
  * suspend_set_ops - Set the global suspend method table.
  * @ops: Suspend operations to use.
  */
 void suspend_set_ops(const struct platform_suspend_ops *ops)
 {
 	lock_system_sleep();

 	suspend_ops = ops;

 	if (valid_state(PM_SUSPEND_STANDBY)) {
 		mem_sleep_states[PM_SUSPEND_STANDBY] = mem_sleep_labels[PM_SUSPEND_STANDBY];
 		pm_states[PM_SUSPEND_STANDBY] = pm_labels[PM_SUSPEND_STANDBY];
 		if (mem_sleep_default == PM_SUSPEND_STANDBY)
 			mem_sleep_current = PM_SUSPEND_STANDBY;
 	}
 	if (valid_state(PM_SUSPEND_MEM)) {
 		mem_sleep_states[PM_SUSPEND_MEM] = mem_sleep_labels[PM_SUSPEND_MEM];
 		if (mem_sleep_default >= PM_SUSPEND_MEM)
 			mem_sleep_current = PM_SUSPEND_MEM;
 	}

 	unlock_system_sleep();
 }
 EXPORT_SYMBOL_GPL(suspend_set_ops);

 /**
  * suspend_valid_only_mem - Generic memory-only valid callback.
  *
  * Platform drivers that implement mem suspend only and only need to check for
  * that in their .valid() callback can use this instead of rolling their own
  * .valid() callback.
  */
 int suspend_valid_only_mem(suspend_state_t state)
 {
 	return state == PM_SUSPEND_MEM;
 }
 EXPORT_SYMBOL_GPL(suspend_valid_only_mem);

 static bool sleep_state_supported(suspend_state_t state)
 {
 	return state == PM_SUSPEND_TO_IDLE || (suspend_ops && suspend_ops->enter);
 }

 static int platform_suspend_prepare(suspend_state_t state)
 {
 	return state != PM_SUSPEND_TO_IDLE && suspend_ops->prepare ?
 		suspend_ops->prepare() : 0;
 }

 static int platform_suspend_prepare_late(suspend_state_t state)
 {
 	return state == PM_SUSPEND_TO_IDLE && s2idle_ops && s2idle_ops->prepare ?
 		s2idle_ops->prepare() : 0;
 }

 static int platform_suspend_prepare_noirq(suspend_state_t state)
 {
 	if (state == PM_SUSPEND_TO_IDLE)
 		return s2idle_ops && s2idle_ops->prepare_late ?
 			s2idle_ops->prepare_late() : 0;

 	return suspend_ops->prepare_late ? suspend_ops->prepare_late() : 0;
 }

 static void platform_resume_noirq(suspend_state_t state)
 {
 	if (state == PM_SUSPEND_TO_IDLE) {
 		if (s2idle_ops && s2idle_ops->restore_early)
 			s2idle_ops->restore_early();
 	} else if (suspend_ops->wake) {
 		suspend_ops->wake();
 	}
 }

 static void platform_resume_early(suspend_state_t state)
 {
 	if (state == PM_SUSPEND_TO_IDLE && s2idle_ops && s2idle_ops->restore)
 		s2idle_ops->restore();
 }

 static void platform_resume_finish(suspend_state_t state)
 {
 	if (state != PM_SUSPEND_TO_IDLE && suspend_ops->finish)
 		suspend_ops->finish();
 }

 static int platform_suspend_begin(suspend_state_t state)
 {
 	if (state == PM_SUSPEND_TO_IDLE && s2idle_ops && s2idle_ops->begin)
 		return s2idle_ops->begin();
 	else if (suspend_ops && suspend_ops->begin)
 		return suspend_ops->begin(state);
 	else
 		return 0;
 }

 static void platform_resume_end(suspend_state_t state)
 {
 	if (state == PM_SUSPEND_TO_IDLE && s2idle_ops && s2idle_ops->end)
 		s2idle_ops->end();
 	else if (suspend_ops && suspend_ops->end)
 		suspend_ops->end();
 }

 static void platform_recover(suspend_state_t state)
 {
 	if (state != PM_SUSPEND_TO_IDLE && suspend_ops->recover)
 		suspend_ops->recover();
 }

 static bool platform_suspend_again(suspend_state_t state)
 {
 	return state != PM_SUSPEND_TO_IDLE && suspend_ops->suspend_again ?
 		suspend_ops->suspend_again() : false;
 }

 #ifdef CONFIG_PM_DEBUG
 static unsigned int pm_test_delay = 5;
 module_param(pm_test_delay, uint, 0644);
 MODULE_PARM_DESC(pm_test_delay,
 		 "Number of seconds to wait before resuming from suspend test");
 #endif

 static int suspend_test(int level)
 {
 #ifdef CONFIG_PM_DEBUG
 	if (pm_test_level == level) {
 		pr_info("suspend debug: Waiting for %d second(s).\n",
 				pm_test_delay);
 		mdelay(pm_test_delay * 1000);
 		return 1;
 	}
 #endif /* !CONFIG_PM_DEBUG */
 	return 0;
 }

 /**
  * suspend_prepare - Prepare for entering system sleep state.
  *
  * Common code run for every system sleep state that can be entered (except for
  * hibernation).  Run suspend notifiers, allocate the "suspend" console and
  * freeze processes.
  */
 static int suspend_prepare(suspend_state_t state)
 {
 	int error;

 	if (!sleep_state_supported(state))
 		return -EPERM;

 	pm_prepare_console();

 	error = pm_notifier_call_chain_robust(PM_SUSPEND_PREPARE, PM_POST_SUSPEND);
 	if (error)
 		goto Restore;

 	trace_suspend_resume(TPS("freeze_processes"), 0, true);
 	error = suspend_freeze_processes();
 	trace_suspend_resume(TPS("freeze_processes"), 0, false);
 	if (!error)
 		return 0;

 	suspend_stats.failed_freeze++;
 	dpm_save_failed_step(SUSPEND_FREEZE);
 	pm_notifier_call_chain(PM_POST_SUSPEND);
  Restore:
 	pm_restore_console();
 	return error;
 }

 /* default implementation */
 void __weak arch_suspend_disable_irqs(void)
 {
 	local_irq_disable();
 }

 /* default implementation */
 void __weak arch_suspend_enable_irqs(void)
 {
 	local_irq_enable();
 }

 /**
  * suspend_enter - Make the system enter the given sleep state.
  * @state: System sleep state to enter.
  * @wakeup: Returns information that the sleep state should not be re-entered.
  *
  * This function should be called after devices have been suspended.
  */
 static int suspend_enter(suspend_state_t state, bool *wakeup)
 {
 	int error;

 	error = platform_suspend_prepare(state);
 	if (error)
 		goto Platform_finish;

 	error = dpm_suspend_late(PMSG_SUSPEND);
 	if (error) {
 		pr_err("late suspend of devices failed\n");
 		goto Platform_finish;
 	}
 	error = platform_suspend_prepare_late(state);
 	if (error)
 		goto Devices_early_resume;

 	error = dpm_suspend_noirq(PMSG_SUSPEND);
 	if (error) {
 		pr_err("noirq suspend of devices failed\n");
 		goto Platform_early_resume;
 	}
 	error = platform_suspend_prepare_noirq(state);
 	if (error)
 		goto Platform_wake;

 	if (suspend_test(TEST_PLATFORM))
 		goto Platform_wake;

 	if (state == PM_SUSPEND_TO_IDLE) {
 		s2idle_loop();
 		goto Platform_wake;
 	}

 	error = suspend_disable_secondary_cpus();
 	if (error || suspend_test(TEST_CPUS))
 		goto Enable_cpus;

 	arch_suspend_disable_irqs();
 	BUG_ON(!irqs_disabled());

 	system_state = SYSTEM_SUSPEND;

 	error = syscore_suspend();
 	if (!error) {
 		*wakeup = pm_wakeup_pending();
 		if (!(suspend_test(TEST_CORE) || *wakeup)) {
 			trace_suspend_resume(TPS("machine_suspend"),
 				state, true);
 			error = suspend_ops->enter(state);
 			trace_suspend_resume(TPS("machine_suspend"),
 				state, false);
 		} else if (*wakeup) {
 			error = -EBUSY;
 		}
 		syscore_resume();
 	}

 	system_state = SYSTEM_RUNNING;

 	arch_suspend_enable_irqs();
 	BUG_ON(irqs_disabled());

  Enable_cpus:
 	suspend_enable_secondary_cpus();

  Platform_wake:
 	platform_resume_noirq(state);
 	dpm_resume_noirq(PMSG_RESUME);

  Platform_early_resume:
 	platform_resume_early(state);

  Devices_early_resume:
 	dpm_resume_early(PMSG_RESUME);

  Platform_finish:
 	platform_resume_finish(state);
 	return error;
 }

 /**
  * suspend_devices_and_enter - Suspend devices and enter system sleep state.
  * @state: System sleep state to enter.
  */
 int suspend_devices_and_enter(suspend_state_t state)
 {
 	int error;
 	bool wakeup = false;

 	if (!sleep_state_supported(state))
 		return -ENOSYS;

 	pm_suspend_target_state = state;

 	if (state == PM_SUSPEND_TO_IDLE)
 		pm_set_suspend_no_platform();

 	error = platform_suspend_begin(state);
 	if (error)
 		goto Close;

 	suspend_console();
 	suspend_test_start();
 	error = dpm_suspend_start(PMSG_SUSPEND);
 	if (error) {
 		pr_err("Some devices failed to suspend, or early wake event detected\n");
 		goto Recover_platform;
 	}
 	suspend_test_finish("suspend devices");
 	if (suspend_test(TEST_DEVICES))
 		goto Recover_platform;

 	do {
 		error = suspend_enter(state, &wakeup);
 	} while (!error && !wakeup && platform_suspend_again(state));

  Resume_devices:
 	suspend_test_start();
 	dpm_resume_end(PMSG_RESUME);
 	suspend_test_finish("resume devices");
 	trace_suspend_resume(TPS("resume_console"), state, true);
 	resume_console();
 	trace_suspend_resume(TPS("resume_console"), state, false);

  Close:
 	platform_resume_end(state);
 	pm_suspend_target_state = PM_SUSPEND_ON;
 	return error;

  Recover_platform:
 	platform_recover(state);
 	goto Resume_devices;
 }

 /**
  * suspend_finish - Clean up before finishing the suspend sequence.
  *
  * Call platform code to clean up, restart processes, and free the console that
  * we've allocated. This routine is not called for hibernation.
  */
 static void suspend_finish(void)
 {
 	suspend_thaw_processes();
 	pm_notifier_call_chain(PM_POST_SUSPEND);
 	pm_restore_console();
 }

 /**
  * enter_state - Do common work needed to enter system sleep state.
  * @state: System sleep state to enter.
  *
  * Make sure that no one else is trying to put the system into a sleep state.
  * Fail if that's not the case.  Otherwise, prepare for system suspend, make the
  * system enter the given sleep state and clean up after wakeup.
  */
 static int enter_state(suspend_state_t state)
 {
 	int error;

 	trace_suspend_resume(TPS("suspend_enter"), state, true);
 	if (state == PM_SUSPEND_TO_IDLE) {
 #ifdef CONFIG_PM_DEBUG
 		if (pm_test_level != TEST_NONE && pm_test_level <= TEST_CPUS) {
 			pr_warn("Unsupported test mode for suspend to idle, please choose none/freezer/devices/platform.\n");
 			return -EAGAIN;
 		}
 #endif
 	} else if (!valid_state(state)) {
 		return -EINVAL;
 	}
 	if (!mutex_trylock(&system_transition_mutex))
 		return -EBUSY;

 	if (state == PM_SUSPEND_TO_IDLE)
 		s2idle_begin();

 	if (sync_on_suspend_enabled) {
 		trace_suspend_resume(TPS("sync_filesystems"), 0, true);
 		ksys_sync_helper();
 		trace_suspend_resume(TPS("sync_filesystems"), 0, false);
 	}

 	pm_pr_dbg("Preparing system for sleep (%s)\n", mem_sleep_labels[state]);
 	pm_suspend_clear_flags();
 	error = suspend_prepare(state);
 	if (error)
 		goto Unlock;

 	if (suspend_test(TEST_FREEZER))
 		goto Finish;

 	trace_suspend_resume(TPS("suspend_enter"), state, false);
 	pm_pr_dbg("Suspending system (%s)\n", mem_sleep_labels[state]);
 	pm_restrict_gfp_mask();
 	error = suspend_devices_and_enter(state);
 	pm_restore_gfp_mask();

  Finish:
 	events_check_enabled = false;
 	pm_pr_dbg("Finishing wakeup.\n");
 	suspend_finish();
  Unlock:
 	mutex_unlock(&system_transition_mutex);
 	return error;
 }

 /**
  * pm_suspend - Externally visible function for suspending the system.
  * @state: System sleep state to enter.
  *
  * Check if the value of @state represents one of the supported states,
  * execute enter_state() and update system suspend statistics.
  */
 int pm_suspend(suspend_state_t state)
 {
 	int error;

 	if (state <= PM_SUSPEND_ON || state >= PM_SUSPEND_MAX)
 		return -EINVAL;

 	pr_info("suspend entry (%s)\n", mem_sleep_labels[state]);
 	error = enter_state(state);
 	if (error) {
 		suspend_stats.fail++;
 		dpm_save_failed_errno(error);
 	} else {
 		suspend_stats.success++;
 	}
 	pr_info("suspend exit\n");
 	return error;
 }
 EXPORT_SYMBOL(pm_suspend);
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* kernel/power/suspend.c - Suspend to RAM and standby functionality.
	*
	* Copyright (c) 2003 Patrick Mochel
	* Copyright (c) 2003 Open Source Development Lab
	* Copyright (c) 2009 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
	*/

	#define pr_fmt(fmt) "PM: " fmt

	#include <linux/string.h>
	#include <linux/delay.h>
	#include <linux/errno.h>
	#include <linux/init.h>
	#include <linux/console.h>
	#include <linux/cpu.h>
	#include <linux/cpuidle.h>
	#include <linux/gfp.h>
	#include <linux/io.h>
	#include <linux/kernel.h>
	#include <linux/list.h>
	#include <linux/mm.h>
	#include <linux/slab.h>
	#include <linux/export.h>
	#include <linux/suspend.h>
	#include <linux/syscore_ops.h>
	#include <linux/swait.h>
	#include <linux/ftrace.h>
	#include <trace/events/power.h>
	#include <linux/compiler.h>
	#include <linux/moduleparam.h>

	#include "power.h"

	const char * const pm_labels[] = {
	[PM_SUSPEND_TO_IDLE] = "freeze",
	[PM_SUSPEND_STANDBY] = "standby",
	[PM_SUSPEND_MEM] = "mem",
	};
	const char *pm_states[PM_SUSPEND_MAX];
	static const char * const mem_sleep_labels[] = {
	[PM_SUSPEND_TO_IDLE] = "s2idle",
	[PM_SUSPEND_STANDBY] = "shallow",
	[PM_SUSPEND_MEM] = "deep",
	};
	const char *mem_sleep_states[PM_SUSPEND_MAX];

	suspend_state_t mem_sleep_current = PM_SUSPEND_TO_IDLE;
	suspend_state_t mem_sleep_default = PM_SUSPEND_MAX;
	suspend_state_t pm_suspend_target_state;
	EXPORT_SYMBOL_GPL(pm_suspend_target_state);

	unsigned int pm_suspend_global_flags;
	EXPORT_SYMBOL_GPL(pm_suspend_global_flags);

	static const struct platform_suspend_ops *suspend_ops;
	static const struct platform_s2idle_ops *s2idle_ops;
	static DECLARE_SWAIT_QUEUE_HEAD(s2idle_wait_head);

	enum s2idle_states __read_mostly s2idle_state;
	static DEFINE_RAW_SPINLOCK(s2idle_lock);

	/**
	* pm_suspend_default_s2idle - Check if suspend-to-idle is the default suspend.
	*
	* Return 'true' if suspend-to-idle has been selected as the default system
	* suspend method.
	*/
	bool pm_suspend_default_s2idle(void)
	{
	return mem_sleep_current == PM_SUSPEND_TO_IDLE;
	}
	EXPORT_SYMBOL_GPL(pm_suspend_default_s2idle);

	void s2idle_set_ops(const struct platform_s2idle_ops *ops)
	{
	lock_system_sleep();
	s2idle_ops = ops;
	unlock_system_sleep();
	}

	static void s2idle_begin(void)
	{
	s2idle_state = S2IDLE_STATE_NONE;
	}

	static void s2idle_enter(void)
	{
	trace_suspend_resume(TPS("machine_suspend"), PM_SUSPEND_TO_IDLE, true);

	raw_spin_lock_irq(&s2idle_lock);
	if (pm_wakeup_pending())
	goto out;

	s2idle_state = S2IDLE_STATE_ENTER;
	raw_spin_unlock_irq(&s2idle_lock);

	get_online_cpus();
	cpuidle_resume();

	/* Push all the CPUs into the idle loop. */
	wake_up_all_idle_cpus();
	/* Make the current CPU wait so it can enter the idle loop too. */
	swait_event_exclusive(s2idle_wait_head,
	s2idle_state == S2IDLE_STATE_WAKE);

	cpuidle_pause();
	put_online_cpus();

	raw_spin_lock_irq(&s2idle_lock);

	out:
	s2idle_state = S2IDLE_STATE_NONE;
	raw_spin_unlock_irq(&s2idle_lock);

	trace_suspend_resume(TPS("machine_suspend"), PM_SUSPEND_TO_IDLE, false);
	}

	static void s2idle_loop(void)
	{
	pm_pr_dbg("suspend-to-idle\n");

	/*
	* Suspend-to-idle equals:
	* frozen processes + suspended devices + idle processors.
	* Thus s2idle_enter() should be called right after all devices have
	* been suspended.
	*
	* Wakeups during the noirq suspend of devices may be spurious, so try
	* to avoid them upfront.
	*/
	for (;;) {
	if (s2idle_ops && s2idle_ops->wake) {
	if (s2idle_ops->wake())
	break;
	} else if (pm_wakeup_pending()) {
	break;
	}

	pm_wakeup_clear(false);

	s2idle_enter();
	}

	pm_pr_dbg("resume from suspend-to-idle\n");
	}

	void s2idle_wake(void)
	{
	unsigned long flags;

	raw_spin_lock_irqsave(&s2idle_lock, flags);
	if (s2idle_state > S2IDLE_STATE_NONE) {
	s2idle_state = S2IDLE_STATE_WAKE;
	swake_up_one(&s2idle_wait_head);
	}
	raw_spin_unlock_irqrestore(&s2idle_lock, flags);
	}
	EXPORT_SYMBOL_GPL(s2idle_wake);

	static bool valid_state(suspend_state_t state)
	{
	/*
	* PM_SUSPEND_STANDBY and PM_SUSPEND_MEM states need low level
	* support and need to be valid to the low level
	* implementation, no valid callback implies that none are valid.
	*/
	return suspend_ops && suspend_ops->valid && suspend_ops->valid(state);
	}

	void __init pm_states_init(void)
	{
	/* "mem" and "freeze" are always present in /sys/power/state. */
	pm_states[PM_SUSPEND_MEM] = pm_labels[PM_SUSPEND_MEM];
	pm_states[PM_SUSPEND_TO_IDLE] = pm_labels[PM_SUSPEND_TO_IDLE];
	/*
	* Suspend-to-idle should be supported even without any suspend_ops,
	* initialize mem_sleep_states[] accordingly here.
	*/
	mem_sleep_states[PM_SUSPEND_TO_IDLE] = mem_sleep_labels[PM_SUSPEND_TO_IDLE];
	}

	static int __init mem_sleep_default_setup(char *str)
	{
	suspend_state_t state;

	for (state = PM_SUSPEND_TO_IDLE; state <= PM_SUSPEND_MEM; state++)
	if (mem_sleep_labels[state] &&
	!strcmp(str, mem_sleep_labels[state])) {
	mem_sleep_default = state;
	break;
	}

	return 1;
	}
	__setup("mem_sleep_default=", mem_sleep_default_setup);

	/**
	* suspend_set_ops - Set the global suspend method table.
	* @ops: Suspend operations to use.
	*/
	void suspend_set_ops(const struct platform_suspend_ops *ops)
	{
	lock_system_sleep();

	suspend_ops = ops;

	if (valid_state(PM_SUSPEND_STANDBY)) {
	mem_sleep_states[PM_SUSPEND_STANDBY] = mem_sleep_labels[PM_SUSPEND_STANDBY];
	pm_states[PM_SUSPEND_STANDBY] = pm_labels[PM_SUSPEND_STANDBY];
	if (mem_sleep_default == PM_SUSPEND_STANDBY)
	mem_sleep_current = PM_SUSPEND_STANDBY;
	}
	if (valid_state(PM_SUSPEND_MEM)) {
	mem_sleep_states[PM_SUSPEND_MEM] = mem_sleep_labels[PM_SUSPEND_MEM];
	if (mem_sleep_default >= PM_SUSPEND_MEM)
	mem_sleep_current = PM_SUSPEND_MEM;
	}

	unlock_system_sleep();
	}
	EXPORT_SYMBOL_GPL(suspend_set_ops);

	/**
	* suspend_valid_only_mem - Generic memory-only valid callback.
	*
	* Platform drivers that implement mem suspend only and only need to check for
	* that in their .valid() callback can use this instead of rolling their own
	* .valid() callback.
	*/
	int suspend_valid_only_mem(suspend_state_t state)
	{
	return state == PM_SUSPEND_MEM;
	}
	EXPORT_SYMBOL_GPL(suspend_valid_only_mem);

	static bool sleep_state_supported(suspend_state_t state)
	{
	return state == PM_SUSPEND_TO_IDLE \|\| (suspend_ops && suspend_ops->enter);
	}

	static int platform_suspend_prepare(suspend_state_t state)
	{
	return state != PM_SUSPEND_TO_IDLE && suspend_ops->prepare ?
	suspend_ops->prepare() : 0;
	}

	static int platform_suspend_prepare_late(suspend_state_t state)
	{
	return state == PM_SUSPEND_TO_IDLE && s2idle_ops && s2idle_ops->prepare ?
	s2idle_ops->prepare() : 0;
	}

	static int platform_suspend_prepare_noirq(suspend_state_t state)
	{
	if (state == PM_SUSPEND_TO_IDLE)
	return s2idle_ops && s2idle_ops->prepare_late ?
	s2idle_ops->prepare_late() : 0;

	return suspend_ops->prepare_late ? suspend_ops->prepare_late() : 0;
	}

	static void platform_resume_noirq(suspend_state_t state)
	{
	if (state == PM_SUSPEND_TO_IDLE) {
	if (s2idle_ops && s2idle_ops->restore_early)
	s2idle_ops->restore_early();
	} else if (suspend_ops->wake) {
	suspend_ops->wake();
	}
	}

	static void platform_resume_early(suspend_state_t state)
	{
	if (state == PM_SUSPEND_TO_IDLE && s2idle_ops && s2idle_ops->restore)
	s2idle_ops->restore();
	}

	static void platform_resume_finish(suspend_state_t state)
	{
	if (state != PM_SUSPEND_TO_IDLE && suspend_ops->finish)
	suspend_ops->finish();
	}

	static int platform_suspend_begin(suspend_state_t state)
	{
	if (state == PM_SUSPEND_TO_IDLE && s2idle_ops && s2idle_ops->begin)
	return s2idle_ops->begin();
	else if (suspend_ops && suspend_ops->begin)
	return suspend_ops->begin(state);
	else
	return 0;
	}

	static void platform_resume_end(suspend_state_t state)
	{
	if (state == PM_SUSPEND_TO_IDLE && s2idle_ops && s2idle_ops->end)
	s2idle_ops->end();
	else if (suspend_ops && suspend_ops->end)
	suspend_ops->end();
	}

	static void platform_recover(suspend_state_t state)
	{
	if (state != PM_SUSPEND_TO_IDLE && suspend_ops->recover)
	suspend_ops->recover();
	}

	static bool platform_suspend_again(suspend_state_t state)
	{
	return state != PM_SUSPEND_TO_IDLE && suspend_ops->suspend_again ?
	suspend_ops->suspend_again() : false;
	}

	#ifdef CONFIG_PM_DEBUG
	static unsigned int pm_test_delay = 5;
	module_param(pm_test_delay, uint, 0644);
	MODULE_PARM_DESC(pm_test_delay,
	"Number of seconds to wait before resuming from suspend test");
	#endif

	static int suspend_test(int level)
	{
	#ifdef CONFIG_PM_DEBUG
	if (pm_test_level == level) {
	pr_info("suspend debug: Waiting for %d second(s).\n",
	pm_test_delay);
	mdelay(pm_test_delay * 1000);
	return 1;
	}
	#endif /* !CONFIG_PM_DEBUG */
	return 0;
	}

	/**
	* suspend_prepare - Prepare for entering system sleep state.
	*
	* Common code run for every system sleep state that can be entered (except for
	* hibernation). Run suspend notifiers, allocate the "suspend" console and
	* freeze processes.
	*/
	static int suspend_prepare(suspend_state_t state)
	{
	int error;

	if (!sleep_state_supported(state))
	return -EPERM;

	pm_prepare_console();

	error = pm_notifier_call_chain_robust(PM_SUSPEND_PREPARE, PM_POST_SUSPEND);
	if (error)
	goto Restore;

	trace_suspend_resume(TPS("freeze_processes"), 0, true);
	error = suspend_freeze_processes();
	trace_suspend_resume(TPS("freeze_processes"), 0, false);
	if (!error)
	return 0;

	suspend_stats.failed_freeze++;
	dpm_save_failed_step(SUSPEND_FREEZE);
	pm_notifier_call_chain(PM_POST_SUSPEND);
	Restore:
	pm_restore_console();
	return error;
	}

	/* default implementation */
	void __weak arch_suspend_disable_irqs(void)
	{
	local_irq_disable();
	}

	/* default implementation */
	void __weak arch_suspend_enable_irqs(void)
	{
	local_irq_enable();
	}

	/**
	* suspend_enter - Make the system enter the given sleep state.
	* @state: System sleep state to enter.
	* @wakeup: Returns information that the sleep state should not be re-entered.
	*
	* This function should be called after devices have been suspended.
	*/
	static int suspend_enter(suspend_state_t state, bool *wakeup)
	{
	int error;

	error = platform_suspend_prepare(state);
	if (error)
	goto Platform_finish;

	error = dpm_suspend_late(PMSG_SUSPEND);
	if (error) {
	pr_err("late suspend of devices failed\n");
	goto Platform_finish;
	}
	error = platform_suspend_prepare_late(state);
	if (error)
	goto Devices_early_resume;

	error = dpm_suspend_noirq(PMSG_SUSPEND);
	if (error) {
	pr_err("noirq suspend of devices failed\n");
	goto Platform_early_resume;
	}
	error = platform_suspend_prepare_noirq(state);
	if (error)
	goto Platform_wake;

	if (suspend_test(TEST_PLATFORM))
	goto Platform_wake;

	if (state == PM_SUSPEND_TO_IDLE) {
	s2idle_loop();
	goto Platform_wake;
	}

	error = suspend_disable_secondary_cpus();
	if (error \|\| suspend_test(TEST_CPUS))
	goto Enable_cpus;

	arch_suspend_disable_irqs();
	BUG_ON(!irqs_disabled());

	system_state = SYSTEM_SUSPEND;

	error = syscore_suspend();
	if (!error) {
	*wakeup = pm_wakeup_pending();
	if (!(suspend_test(TEST_CORE) \|\| *wakeup)) {
	trace_suspend_resume(TPS("machine_suspend"),
	state, true);
	error = suspend_ops->enter(state);
	trace_suspend_resume(TPS("machine_suspend"),
	state, false);
	} else if (*wakeup) {
	error = -EBUSY;
	}
	syscore_resume();
	}

	system_state = SYSTEM_RUNNING;

	arch_suspend_enable_irqs();
	BUG_ON(irqs_disabled());

	Enable_cpus:
	suspend_enable_secondary_cpus();

	Platform_wake:
	platform_resume_noirq(state);
	dpm_resume_noirq(PMSG_RESUME);

	Platform_early_resume:
	platform_resume_early(state);

	Devices_early_resume:
	dpm_resume_early(PMSG_RESUME);

	Platform_finish:
	platform_resume_finish(state);
	return error;
	}

	/**
	* suspend_devices_and_enter - Suspend devices and enter system sleep state.
	* @state: System sleep state to enter.
	*/
	int suspend_devices_and_enter(suspend_state_t state)
	{
	int error;
	bool wakeup = false;

	if (!sleep_state_supported(state))
	return -ENOSYS;

	pm_suspend_target_state = state;

	if (state == PM_SUSPEND_TO_IDLE)
	pm_set_suspend_no_platform();

	error = platform_suspend_begin(state);
	if (error)
	goto Close;

	suspend_console();
	suspend_test_start();
	error = dpm_suspend_start(PMSG_SUSPEND);
	if (error) {
	pr_err("Some devices failed to suspend, or early wake event detected\n");
	goto Recover_platform;
	}
	suspend_test_finish("suspend devices");
	if (suspend_test(TEST_DEVICES))
	goto Recover_platform;

	do {
	error = suspend_enter(state, &wakeup);
	} while (!error && !wakeup && platform_suspend_again(state));

	Resume_devices:
	suspend_test_start();
	dpm_resume_end(PMSG_RESUME);
	suspend_test_finish("resume devices");
	trace_suspend_resume(TPS("resume_console"), state, true);
	resume_console();
	trace_suspend_resume(TPS("resume_console"), state, false);

	Close:
	platform_resume_end(state);
	pm_suspend_target_state = PM_SUSPEND_ON;
	return error;

	Recover_platform:
	platform_recover(state);
	goto Resume_devices;
	}

	/**
	* suspend_finish - Clean up before finishing the suspend sequence.
	*
	* Call platform code to clean up, restart processes, and free the console that
	* we've allocated. This routine is not called for hibernation.
	*/
	static void suspend_finish(void)
	{
	suspend_thaw_processes();
	pm_notifier_call_chain(PM_POST_SUSPEND);
	pm_restore_console();
	}

	/**
	* enter_state - Do common work needed to enter system sleep state.
	* @state: System sleep state to enter.
	*
	* Make sure that no one else is trying to put the system into a sleep state.
	* Fail if that's not the case. Otherwise, prepare for system suspend, make the
	* system enter the given sleep state and clean up after wakeup.
	*/
	static int enter_state(suspend_state_t state)
	{
	int error;

	trace_suspend_resume(TPS("suspend_enter"), state, true);
	if (state == PM_SUSPEND_TO_IDLE) {
	#ifdef CONFIG_PM_DEBUG
	if (pm_test_level != TEST_NONE && pm_test_level <= TEST_CPUS) {
	pr_warn("Unsupported test mode for suspend to idle, please choose none/freezer/devices/platform.\n");
	return -EAGAIN;
	}
	#endif
	} else if (!valid_state(state)) {
	return -EINVAL;
	}
	if (!mutex_trylock(&system_transition_mutex))
	return -EBUSY;

	if (state == PM_SUSPEND_TO_IDLE)
	s2idle_begin();

	if (sync_on_suspend_enabled) {
	trace_suspend_resume(TPS("sync_filesystems"), 0, true);
	ksys_sync_helper();
	trace_suspend_resume(TPS("sync_filesystems"), 0, false);
	}

	pm_pr_dbg("Preparing system for sleep (%s)\n", mem_sleep_labels[state]);
	pm_suspend_clear_flags();
	error = suspend_prepare(state);
	if (error)
	goto Unlock;

	if (suspend_test(TEST_FREEZER))
	goto Finish;

	trace_suspend_resume(TPS("suspend_enter"), state, false);
	pm_pr_dbg("Suspending system (%s)\n", mem_sleep_labels[state]);
	pm_restrict_gfp_mask();
	error = suspend_devices_and_enter(state);
	pm_restore_gfp_mask();

	Finish:
	events_check_enabled = false;
	pm_pr_dbg("Finishing wakeup.\n");
	suspend_finish();
	Unlock:
	mutex_unlock(&system_transition_mutex);
	return error;
	}

	/**
	* pm_suspend - Externally visible function for suspending the system.
	* @state: System sleep state to enter.
	*
	* Check if the value of @state represents one of the supported states,
	* execute enter_state() and update system suspend statistics.
	*/
	int pm_suspend(suspend_state_t state)
	{
	int error;

	if (state <= PM_SUSPEND_ON \|\| state >= PM_SUSPEND_MAX)
	return -EINVAL;

	pr_info("suspend entry (%s)\n", mem_sleep_labels[state]);
	error = enter_state(state);
	if (error) {
	suspend_stats.fail++;
	dpm_save_failed_errno(error);
	} else {
	suspend_stats.success++;
	}
	pr_info("suspend exit\n");
	return error;
	}
	EXPORT_SYMBOL(pm_suspend);