main.c

Kernel code of linux kernel

/*
 * kernel/power/main.c - PM subsystem core functionality.
 *
 * Copyright (c) 2003 Patrick Mochel
 * Copyright (c) 2003 Open Source Development Lab
 * 
 * This file is released under the GPLv2
 *
 */

#include <linux/module.h>
#include <linux/suspend.h>
#include <linux/kobject.h>
#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/resume-trace.h>
#include <linux/freezer.h>
#include <linux/vmstat.h>
#include <linux/syscalls.h>
#include <linux/ftrace.h>

#include "power.h"

DEFINE_MUTEX(pm_mutex);

unsigned int pm_flags;
EXPORT_SYMBOL(pm_flags);

#ifdef CONFIG_PM_SLEEP

/* Routines for PM-transition notifications */

static BLOCKING_NOTIFIER_HEAD(pm_chain_head);

int register_pm_notifier(struct notifier_block *nb)
{
	return blocking_notifier_chain_register(&pm_chain_head, nb);
}
EXPORT_SYMBOL_GPL(register_pm_notifier);

int unregister_pm_notifier(struct notifier_block *nb)
{
	return blocking_notifier_chain_unregister(&pm_chain_head, nb);
}
EXPORT_SYMBOL_GPL(unregister_pm_notifier);

int pm_notifier_call_chain(unsigned long val)
{
	return (blocking_notifier_call_chain(&pm_chain_head, val, NULL)
			== NOTIFY_BAD) ? -EINVAL : 0;
}

#ifdef CONFIG_PM_DEBUG
int pm_test_level = TEST_NONE;

static int suspend_test(int level)
{
	if (pm_test_level == level) {
		printk(KERN_INFO "suspend debug: Waiting for 5 seconds.\n");
		mdelay(5000);
		return 1;
	}
	return 0;
}

static const char * const pm_tests[__TEST_AFTER_LAST] = {
	[TEST_NONE] = "none",
	[TEST_CORE] = "core",
	[TEST_CPUS] = "processors",
	[TEST_PLATFORM] = "platform",
	[TEST_DEVICES] = "devices",
	[TEST_FREEZER] = "freezer",
};

static ssize_t pm_test_show(struct kobject *kobj, struct kobj_attribute *attr,
				char *buf)
{
	char *s = buf;
	int level;

	for (level = TEST_FIRST; level <= TEST_MAX; level++)
		if (pm_tests[level]) {
			if (level == pm_test_level)
				s += sprintf(s, "[%s] ", pm_tests[level]);
			else
				s += sprintf(s, "%s ", pm_tests[level]);
		}

	if (s != buf)
		/* convert the last space to a newline */
		*(s-1) = '\n';

	return (s - buf);
}

static ssize_t pm_test_store(struct kobject *kobj, struct kobj_attribute *attr,
				const char *buf, size_t n)
{
	const char * const *s;
	int level;
	char *p;
	int len;
	int error = -EINVAL;

	p = memchr(buf, '\n', n);
	len = p ? p - buf : n;

	mutex_lock(&pm_mutex);

	level = TEST_FIRST;
	for (s = &pm_tests[level]; level <= TEST_MAX; s++, level++)
		if (*s && len == strlen(*s) && !strncmp(buf, *s, len)) {
			pm_test_level = level;
			error = 0;
			break;
		}

	mutex_unlock(&pm_mutex);

	return error ? error : n;
}

power_attr(pm_test);
#else /* !CONFIG_PM_DEBUG */
static inline int suspend_test(int level) { return 0; }
#endif /* !CONFIG_PM_DEBUG */

#endif /* CONFIG_PM_SLEEP */

#ifdef CONFIG_SUSPEND

#ifdef CONFIG_PM_TEST_SUSPEND

/*
 * We test the system suspend code by setting an RTC wakealarm a short
 * time in the future, then suspending.  Suspending the devices won't
 * normally take long ... some systems only need a few milliseconds.
 *
 * The time it takes is system-specific though, so when we test this
 * during system bootup we allow a LOT of time.
 */
#define TEST_SUSPEND_SECONDS	5

static unsigned long suspend_test_start_time;

static void suspend_test_start(void)
{
	/* FIXME Use better timebase than "jiffies", ideally a clocksource.
	 * What we want is a hardware counter that will work correctly even
	 * during the irqs-are-off stages of the suspend/resume cycle...
	 */
	suspend_test_start_time = jiffies;
}

static void suspend_test_finish(const char *label)
{
	long nj = jiffies - suspend_test_start_time;
	unsigned msec;

	msec = jiffies_to_msecs(abs(nj));
	pr_info("PM: %s took %d.%03d seconds\n", label,
			msec / 1000, msec % 1000);

	/* Warning on suspend means the RTC alarm period needs to be
	 * larger -- the system was sooo slooowwww to suspend that the
	 * alarm (should have) fired before the system went to sleep!
	 *
	 * Warning on either suspend or resume also means the system
	 * has some performance issues.  The stack dump of a WARN_ON
	 * is more likely to get the right attention than a printk...
	 */
	WARN_ON(msec > (TEST_SUSPEND_SECONDS * 1000));
}

#else

static void suspend_test_start(void)
{
}

static void suspend_test_finish(const char *label)
{
}

#endif

/* This is just an arbitrary number */
#define FREE_PAGE_NUMBER (100)

static struct platform_suspend_ops *suspend_ops;

/**
 *	suspend_set_ops - Set the global suspend method table.
 *	@ops:	Pointer to ops structure.
 */

void suspend_set_ops(struct platform_suspend_ops *ops)
{
	mutex_lock(&pm_mutex);
	suspend_ops = ops;
	mutex_unlock(&pm_mutex);
}

/**
 * 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;
}

/**
 *	suspend_prepare - Do prep work before entering low-power state.
 *
 *	This is common code that is called for each state that we're entering.
 *	Run suspend notifiers, allocate a console and stop all processes.
 */
static int suspend_prepare(void)
{
	int error;
	unsigned int free_pages;

	if (!suspend_ops || !suspend_ops->enter)
		return -EPERM;

	pm_prepare_console();

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

	if (suspend_freeze_processes()) {
		error = -EAGAIN;
		goto Thaw;
	}

	free_pages = global_page_state(NR_FREE_PAGES);
	if (free_pages < FREE_PAGE_NUMBER) {
		pr_debug("PM: free some memory\n");
		shrink_all_memory(FREE_PAGE_NUMBER - free_pages);
		if (nr_free_pages() < FREE_PAGE_NUMBER) {
			error = -ENOMEM;
			printk(KERN_ERR "PM: No enough memory\n");
		}
	}
	if (!error)
		return 0;

 Thaw:
	suspend_thaw_processes();
 Finish:
	pm_notifier_call_chain(PM_POST_SUSPEND);
	pm_restore_console();
	return error;
}

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

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

/**
 *	suspend_enter - enter the desired system sleep state.
 *	@state:		state to enter
 *
 *	This function should be called after devices have been suspended.
 */
static int suspend_enter(suspend_state_t state)
{
	int error = 0;

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

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

	if (!suspend_test(TEST_CORE))
		error = suspend_ops->enter(state);

	device_power_up(PMSG_RESUME);
 Done:
	arch_suspend_enable_irqs();
	BUG_ON(irqs_disabled());
	device_pm_unlock();
	return error;
}

/**
 *	suspend_devices_and_enter - suspend devices and enter the desired system
 *				    sleep state.
 *	@state:		  state to enter
 */
int suspend_devices_and_enter(suspend_state_t state)
{
	int error, ftrace_save;

	if (!suspend_ops)
		return -ENOSYS;

	if (suspend_ops->begin) {
		error = suspend_ops->begin(state);
		if (error)
			goto Close;
	}
	suspend_console();
	ftrace_save = __ftrace_enabled_save();
	suspend_test_start();
	error = device_suspend(PMSG_SUSPEND);
	if (error) {
		printk(KERN_ERR "PM: Some devices failed to suspend\n");
		goto Recover_platform;
	}
	suspend_test_finish("suspend devices");
	if (suspend_test(TEST_DEVICES))
		goto Recover_platform;

	if (suspend_ops->prepare) {
		error = suspend_ops->prepare();
		if (error)
			goto Resume_devices;
	}

	if (suspend_test(TEST_PLATFORM))
		goto Finish;

	error = disable_nonboot_cpus();
	if (!error && !suspend_test(TEST_CPUS))
		suspend_enter(state);

	enable_nonboot_cpus();
 Finish:
	if (suspend_ops->finish)
		suspend_ops->finish();
 Resume_devices:
	suspend_test_start();
	device_resume(PMSG_RESUME);
	suspend_test_finish("resume devices");
	__ftrace_enabled_restore(ftrace_save);
	resume_console();
 Close:
	if (suspend_ops->end)
		suspend_ops->end();
	return error;