kernel/power/suspend.c - arm/linux-arm64-legacy - Git at Google

 /*
  * 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.
  *
  * This file is released under the GPLv2.
  */

 #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/syscalls.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/ftrace.h>
 #include <trace/events/power.h>
 #include <linux/compiler.h>

 #include "power.h"

 struct pm_sleep_state pm_states[PM_SUSPEND_MAX] = {
 	[PM_SUSPEND_FREEZE] = { .label = "freeze", .state = PM_SUSPEND_FREEZE },
 	[PM_SUSPEND_STANDBY] = { .label = "standby", },
 	[PM_SUSPEND_MEM] = { .label = "mem", },
 };

 static const struct platform_suspend_ops *suspend_ops;
 static const struct platform_freeze_ops *freeze_ops;

 static bool need_suspend_ops(suspend_state_t state)
 {
 	return state > PM_SUSPEND_FREEZE;
 }

 static DECLARE_WAIT_QUEUE_HEAD(suspend_freeze_wait_head);
 static bool suspend_freeze_wake;

 void freeze_set_ops(const struct platform_freeze_ops *ops)
 {
 	lock_system_sleep();
 	freeze_ops = ops;
 	unlock_system_sleep();
 }

 static void freeze_begin(void)
 {
 	suspend_freeze_wake = false;
 }

 static void freeze_enter(void)
 {
 	cpuidle_use_deepest_state(true);
 	cpuidle_resume();
 	wait_event(suspend_freeze_wait_head, suspend_freeze_wake);
 	cpuidle_pause();
 	cpuidle_use_deepest_state(false);
 }

 void freeze_wake(void)
 {
 	suspend_freeze_wake = true;
 	wake_up(&suspend_freeze_wait_head);
 }
 EXPORT_SYMBOL_GPL(freeze_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);
 }

 /*
  * If this is set, the "mem" label always corresponds to the deepest sleep state
  * available, the "standby" label corresponds to the second deepest sleep state
  * available (if any), and the "freeze" label corresponds to the remaining
  * available sleep state (if there is one).
  */
 static bool relative_states;

 static int __init sleep_states_setup(char *str)
 {
 	relative_states = !strncmp(str, "1", 1);
 	if (relative_states) {
 		pm_states[PM_SUSPEND_MEM].state = PM_SUSPEND_FREEZE;
 		pm_states[PM_SUSPEND_FREEZE].state = 0;
 	}
 	return 1;
 }

 __setup("relative_sleep_states=", sleep_states_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)
 {
 	suspend_state_t i;
 	int j = PM_SUSPEND_MAX - 1;

 	lock_system_sleep();

 	suspend_ops = ops;
 	for (i = PM_SUSPEND_MEM; i >= PM_SUSPEND_STANDBY; i--)
 		if (valid_state(i))
 			pm_states[j--].state = i;
 		else if (!relative_states)
 			pm_states[j--].state = 0;

 	pm_states[j--].state = PM_SUSPEND_FREEZE;
 	while (j >= PM_SUSPEND_MIN)
 		pm_states[j--].state = 0;

 	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 int suspend_test(int level)
 {
 #ifdef CONFIG_PM_DEBUG
 	if (pm_test_level == level) {
 		printk(KERN_INFO "suspend debug: Waiting for 5 seconds.\n");
 		mdelay(5000);
 		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 (need_suspend_ops(state) && (!suspend_ops || !suspend_ops->enter))
 		return -EPERM;

 	pm_prepare_console();

 	error = pm_notifier_call_chain(PM_SUSPEND_PREPARE);
 	if (error)
 		goto Finish;

 	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);
  Finish:
 	pm_notifier_call_chain(PM_POST_SUSPEND);
 	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;

 	if (need_suspend_ops(state) && suspend_ops->prepare) {
 		error = suspend_ops->prepare();
 		if (error)
 			goto Platform_finish;
 	}

 	error = dpm_suspend_end(PMSG_SUSPEND);
 	if (error) {
 		printk(KERN_ERR "PM: Some devices failed to power down\n");
 		goto Platform_finish;
 	}

 	if (need_suspend_ops(state) && suspend_ops->prepare_late) {
 		error = suspend_ops->prepare_late();
 		if (error)
 			goto Platform_wake;
 	}

 	if (suspend_test(TEST_PLATFORM))
 		goto Platform_wake;

 	/*
 	 * PM_SUSPEND_FREEZE equals
 	 * frozen processes + suspended devices + idle processors.
 	 * Thus we should invoke freeze_enter() soon after
 	 * all the devices are suspended.
 	 */
 	if (state == PM_SUSPEND_FREEZE) {
 		trace_suspend_resume(TPS("machine_suspend"), state, true);
 		freeze_enter();
 		trace_suspend_resume(TPS("machine_suspend"), state, false);
 		goto Platform_wake;
 	}

 	ftrace_stop();
 	error = disable_nonboot_cpus();
 	if (error || suspend_test(TEST_CPUS))
 		goto Enable_cpus;

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

 	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);
 			events_check_enabled = false;
 		}
 		syscore_resume();
 	}

 	arch_suspend_enable_irqs();
 	BUG_ON(irqs_disabled());

  Enable_cpus:
 	enable_nonboot_cpus();
 	ftrace_start();

  Platform_wake:
 	if (need_suspend_ops(state) && suspend_ops->wake)
 		suspend_ops->wake();

 	dpm_resume_start(PMSG_RESUME);

  Platform_finish:
 	if (need_suspend_ops(state) && suspend_ops->finish)
 		suspend_ops->finish();

 	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 (need_suspend_ops(state) && !suspend_ops)
 		return -ENOSYS;

 	if (need_suspend_ops(state) && suspend_ops->begin) {
 		error = suspend_ops->begin(state);
 		if (error)
 			goto Close;
 	} else if (state == PM_SUSPEND_FREEZE && freeze_ops && freeze_ops->begin) {
 		error = freeze_ops->begin();
 		if (error)
 			goto Close;
 	}
 	suspend_console();
 	suspend_test_start();
 	error = dpm_suspend_start(PMSG_SUSPEND);
 	if (error) {
 		pr_err("PM: 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 && need_suspend_ops(state)
 		&& suspend_ops->suspend_again && suspend_ops->suspend_again());

  Resume_devices:
 	suspend_test_start();
 	dpm_resume_end(PMSG_RESUME);
 	suspend_test_finish("resume devices");
 	resume_console();
  Close:
 	if (need_suspend_ops(state) && suspend_ops->end)
 		suspend_ops->end();
 	else if (state == PM_SUSPEND_FREEZE && freeze_ops && freeze_ops->end)
 		freeze_ops->end();

 	return error;

  Recover_platform:
 	if (need_suspend_ops(state) && suspend_ops->recover)
 		suspend_ops->recover();
 	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_FREEZE) {
 #ifdef CONFIG_PM_DEBUG
 		if (pm_test_level != TEST_NONE && pm_test_level <= TEST_CPUS) {
 			pr_warning("PM: Unsupported test mode for freeze state,"
 				   "please choose none/freezer/devices/platform.\n");
 			return -EAGAIN;
 		}
 #endif
 	} else if (!valid_state(state)) {
 		return -EINVAL;
 	}
 	if (!mutex_trylock(&pm_mutex))
 		return -EBUSY;

 	if (state == PM_SUSPEND_FREEZE)
 		freeze_begin();

 	trace_suspend_resume(TPS("sync_filesystems"), 0, true);
 	printk(KERN_INFO "PM: Syncing filesystems ... ");
 	sys_sync();
 	printk("done.\n");
 	trace_suspend_resume(TPS("sync_filesystems"), 0, false);

 	pr_debug("PM: Preparing system for %s sleep\n", pm_states[state].label);
 	error = suspend_prepare(state);
 	if (error)
 		goto Unlock;

 	if (suspend_test(TEST_FREEZER))
 		goto Finish;

 	trace_suspend_resume(TPS("suspend_enter"), state, false);
 	pr_debug("PM: Entering %s sleep\n", pm_states[state].label);
 	pm_restrict_gfp_mask();
 	error = suspend_devices_and_enter(state);
 	pm_restore_gfp_mask();

  Finish:
 	pr_debug("PM: Finishing wakeup.\n");
 	suspend_finish();
  Unlock:
 	mutex_unlock(&pm_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;

 	error = enter_state(state);
 	if (error) {
 		suspend_stats.fail++;
 		dpm_save_failed_errno(error);
 	} else {
 		suspend_stats.success++;
 	}
 	return error;
 }
 EXPORT_SYMBOL(pm_suspend);
	/*
	* 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.
	*
	* This file is released under the GPLv2.
	*/

	#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/syscalls.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/ftrace.h>
	#include <trace/events/power.h>
	#include <linux/compiler.h>

	#include "power.h"

	struct pm_sleep_state pm_states[PM_SUSPEND_MAX] = {
	[PM_SUSPEND_FREEZE] = { .label = "freeze", .state = PM_SUSPEND_FREEZE },
	[PM_SUSPEND_STANDBY] = { .label = "standby", },
	[PM_SUSPEND_MEM] = { .label = "mem", },
	};

	static const struct platform_suspend_ops *suspend_ops;
	static const struct platform_freeze_ops *freeze_ops;

	static bool need_suspend_ops(suspend_state_t state)
	{
	return state > PM_SUSPEND_FREEZE;
	}

	static DECLARE_WAIT_QUEUE_HEAD(suspend_freeze_wait_head);
	static bool suspend_freeze_wake;

	void freeze_set_ops(const struct platform_freeze_ops *ops)
	{
	lock_system_sleep();
	freeze_ops = ops;
	unlock_system_sleep();
	}

	static void freeze_begin(void)
	{
	suspend_freeze_wake = false;
	}

	static void freeze_enter(void)
	{
	cpuidle_use_deepest_state(true);
	cpuidle_resume();
	wait_event(suspend_freeze_wait_head, suspend_freeze_wake);
	cpuidle_pause();
	cpuidle_use_deepest_state(false);
	}

	void freeze_wake(void)
	{
	suspend_freeze_wake = true;
	wake_up(&suspend_freeze_wait_head);
	}
	EXPORT_SYMBOL_GPL(freeze_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);
	}

	/*
	* If this is set, the "mem" label always corresponds to the deepest sleep state
	* available, the "standby" label corresponds to the second deepest sleep state
	* available (if any), and the "freeze" label corresponds to the remaining
	* available sleep state (if there is one).
	*/
	static bool relative_states;

	static int __init sleep_states_setup(char *str)
	{
	relative_states = !strncmp(str, "1", 1);
	if (relative_states) {
	pm_states[PM_SUSPEND_MEM].state = PM_SUSPEND_FREEZE;
	pm_states[PM_SUSPEND_FREEZE].state = 0;
	}
	return 1;
	}

	__setup("relative_sleep_states=", sleep_states_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)
	{
	suspend_state_t i;
	int j = PM_SUSPEND_MAX - 1;

	lock_system_sleep();

	suspend_ops = ops;
	for (i = PM_SUSPEND_MEM; i >= PM_SUSPEND_STANDBY; i--)
	if (valid_state(i))
	pm_states[j--].state = i;
	else if (!relative_states)
	pm_states[j--].state = 0;

	pm_states[j--].state = PM_SUSPEND_FREEZE;
	while (j >= PM_SUSPEND_MIN)
	pm_states[j--].state = 0;

	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 int suspend_test(int level)
	{
	#ifdef CONFIG_PM_DEBUG
	if (pm_test_level == level) {
	printk(KERN_INFO "suspend debug: Waiting for 5 seconds.\n");
	mdelay(5000);
	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 (need_suspend_ops(state) && (!suspend_ops \|\| !suspend_ops->enter))
	return -EPERM;

	pm_prepare_console();

	error = pm_notifier_call_chain(PM_SUSPEND_PREPARE);
	if (error)
	goto Finish;

	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);
	Finish:
	pm_notifier_call_chain(PM_POST_SUSPEND);
	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;

	if (need_suspend_ops(state) && suspend_ops->prepare) {
	error = suspend_ops->prepare();
	if (error)
	goto Platform_finish;
	}

	error = dpm_suspend_end(PMSG_SUSPEND);
	if (error) {
	printk(KERN_ERR "PM: Some devices failed to power down\n");
	goto Platform_finish;
	}

	if (need_suspend_ops(state) && suspend_ops->prepare_late) {
	error = suspend_ops->prepare_late();
	if (error)
	goto Platform_wake;
	}

	if (suspend_test(TEST_PLATFORM))
	goto Platform_wake;

	/*
	* PM_SUSPEND_FREEZE equals
	* frozen processes + suspended devices + idle processors.
	* Thus we should invoke freeze_enter() soon after
	* all the devices are suspended.
	*/
	if (state == PM_SUSPEND_FREEZE) {
	trace_suspend_resume(TPS("machine_suspend"), state, true);
	freeze_enter();
	trace_suspend_resume(TPS("machine_suspend"), state, false);
	goto Platform_wake;
	}

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

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

	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);
	events_check_enabled = false;
	}
	syscore_resume();
	}

	arch_suspend_enable_irqs();
	BUG_ON(irqs_disabled());

	Enable_cpus:
	enable_nonboot_cpus();
	ftrace_start();

	Platform_wake:
	if (need_suspend_ops(state) && suspend_ops->wake)
	suspend_ops->wake();

	dpm_resume_start(PMSG_RESUME);

	Platform_finish:
	if (need_suspend_ops(state) && suspend_ops->finish)
	suspend_ops->finish();

	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 (need_suspend_ops(state) && !suspend_ops)
	return -ENOSYS;

	if (need_suspend_ops(state) && suspend_ops->begin) {
	error = suspend_ops->begin(state);
	if (error)
	goto Close;
	} else if (state == PM_SUSPEND_FREEZE && freeze_ops && freeze_ops->begin) {
	error = freeze_ops->begin();
	if (error)
	goto Close;
	}
	suspend_console();
	suspend_test_start();
	error = dpm_suspend_start(PMSG_SUSPEND);
	if (error) {
	pr_err("PM: 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 && need_suspend_ops(state)
	&& suspend_ops->suspend_again && suspend_ops->suspend_again());

	Resume_devices:
	suspend_test_start();
	dpm_resume_end(PMSG_RESUME);
	suspend_test_finish("resume devices");
	resume_console();
	Close:
	if (need_suspend_ops(state) && suspend_ops->end)
	suspend_ops->end();
	else if (state == PM_SUSPEND_FREEZE && freeze_ops && freeze_ops->end)
	freeze_ops->end();

	return error;

	Recover_platform:
	if (need_suspend_ops(state) && suspend_ops->recover)
	suspend_ops->recover();
	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_FREEZE) {
	#ifdef CONFIG_PM_DEBUG
	if (pm_test_level != TEST_NONE && pm_test_level <= TEST_CPUS) {
	pr_warning("PM: Unsupported test mode for freeze state,"
	"please choose none/freezer/devices/platform.\n");
	return -EAGAIN;
	}
	#endif
	} else if (!valid_state(state)) {
	return -EINVAL;
	}
	if (!mutex_trylock(&pm_mutex))
	return -EBUSY;

	if (state == PM_SUSPEND_FREEZE)
	freeze_begin();

	trace_suspend_resume(TPS("sync_filesystems"), 0, true);
	printk(KERN_INFO "PM: Syncing filesystems ... ");
	sys_sync();
	printk("done.\n");
	trace_suspend_resume(TPS("sync_filesystems"), 0, false);

	pr_debug("PM: Preparing system for %s sleep\n", pm_states[state].label);
	error = suspend_prepare(state);
	if (error)
	goto Unlock;

	if (suspend_test(TEST_FREEZER))
	goto Finish;

	trace_suspend_resume(TPS("suspend_enter"), state, false);
	pr_debug("PM: Entering %s sleep\n", pm_states[state].label);
	pm_restrict_gfp_mask();
	error = suspend_devices_and_enter(state);
	pm_restore_gfp_mask();

	Finish:
	pr_debug("PM: Finishing wakeup.\n");
	suspend_finish();
	Unlock:
	mutex_unlock(&pm_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;

	error = enter_state(state);
	if (error) {
	suspend_stats.fail++;
	dpm_save_failed_errno(error);
	} else {
	suspend_stats.success++;
	}
	return error;
	}
	EXPORT_SYMBOL(pm_suspend);