path: root/kernel/power/main.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * kernel/power/main.c - PM subsystem core functionality.
 *
 * Copyright (c) 2003 Patrick Mochel
 * Copyright (c) 2003 Open Source Development Lab
 */

#include <linux/acpi.h>
#include <linux/export.h>
#include <linux/kobject.h>
#include <linux/string.h>
#include <linux/pm-trace.h>
#include <linux/workqueue.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/suspend.h>
#include <linux/syscalls.h>
#include <linux/pm_runtime.h>

#include "power.h"

#ifdef CONFIG_PM_SLEEP
/*
 * The following functions are used by the suspend/hibernate code to temporarily
 * change gfp_allowed_mask in order to avoid using I/O during memory allocations
 * while devices are suspended.  To avoid races with the suspend/hibernate code,
 * they should always be called with system_transition_mutex held
 * (gfp_allowed_mask also should only be modified with system_transition_mutex
 * held, unless the suspend/hibernate code is guaranteed not to run in parallel
 * with that modification).
 */
static gfp_t saved_gfp_mask;

void pm_restore_gfp_mask(void)
{
	WARN_ON(!mutex_is_locked(&system_transition_mutex));
	if (saved_gfp_mask) {
		gfp_allowed_mask = saved_gfp_mask;
		saved_gfp_mask = 0;
	}
}

void pm_restrict_gfp_mask(void)
{
	WARN_ON(!mutex_is_locked(&system_transition_mutex));
	WARN_ON(saved_gfp_mask);
	saved_gfp_mask = gfp_allowed_mask;
	gfp_allowed_mask &= ~(__GFP_IO | __GFP_FS);
}

unsigned int lock_system_sleep(void)
{
	unsigned int flags = current->flags;
	current->flags |= PF_NOFREEZE;
	mutex_lock(&system_transition_mutex);
	return flags;
}
EXPORT_SYMBOL_GPL(lock_system_sleep);

void unlock_system_sleep(unsigned int flags)
{
	if (!(flags & PF_NOFREEZE))
		current->flags &= ~PF_NOFREEZE;
	mutex_unlock(&system_transition_mutex);
}
EXPORT_SYMBOL_GPL(unlock_system_sleep);

void ksys_sync_helper(void)
{
	ktime_t start;
	long elapsed_msecs;

	start = ktime_get();
	ksys_sync();
	elapsed_msecs = ktime_to_ms(ktime_sub(ktime_get(), start));
	pr_info("Filesystems sync: %ld.%03ld seconds\n",
		elapsed_msecs / MSEC_PER_SEC, elapsed_msecs % MSEC_PER_SEC);
}
EXPORT_SYMBOL_GPL(ksys_sync_helper);

/* 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_robust(unsigned long val_up, unsigned long val_down)
{
	int ret;

	ret = blocking_notifier_call_chain_robust(&pm_chain_head, val_up, val_down, NULL);

	return notifier_to_errno(ret);
}

int pm_notifier_call_chain(unsigned long val)
{
	return blocking_notifier_call_chain(&pm_chain_head, val, NULL);
}

/* If set, devices may be suspended and resumed asynchronously. */
int pm_async_enabled = 1;

static ssize_t pm_async_show(struct kobject *kobj, struct kobj_attribute *attr,
			     char *buf)
{
	return sysfs_emit(buf, "%d\n", pm_async_enabled);
}

static ssize_t pm_async_store(struct kobject *kobj, struct kobj_attribute *attr,
			      const char *buf, size_t n)
{
	unsigned long val;

	if (kstrtoul(buf, 10, &val))
		return -EINVAL;

	if (val > 1)
		return -EINVAL;

	pm_async_enabled = val;
	return n;
}

power_attr(pm_async);

#ifdef CONFIG_SUSPEND
static ssize_t mem_sleep_show(struct kobject *kobj, struct kobj_attribute *attr,
			      char *buf)
{
	ssize_t count = 0;
	suspend_state_t i;

	for (i = PM_SUSPEND_MIN; i < PM_SUSPEND_MAX; i++) {
		if (i >= PM_SUSPEND_MEM && cxl_mem_active())
			continue;
		if (mem_sleep_states[i]) {
			const char *label = mem_sleep_states[i];

			if (mem_sleep_current == i)
				count += sysfs_emit_at(buf, count, "[%s] ", label);
			else
				count += sysfs_emit_at(buf, count, "%s ", label);
		}
	}

	/* Convert the last space to a newline if needed. */
	if (count > 0)
		buf[count - 1] = '\n';

	return count;
}

static suspend_state_t decode_suspend_state(const char *buf, size_t n)
{
	suspend_state_t state;
	char *p;
	int len;

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

	for (state = PM_SUSPEND_MIN; state < PM_SUSPEND_MAX; state++) {
		const char *label = mem_sleep_states[state];

		if (label && len == strlen(label) && !strncmp(buf, label, len))
			return state;
	}

	return PM_SUSPEND_ON;
}

static ssize_t mem_sleep_store(struct kobject *kobj, struct kobj_attribute *attr,
			       const char *buf, size_t n)
{
	suspend_state_t state;
	int error;

	error = pm_autosleep_lock();
	if (error)
		return error;

	if (pm_autosleep_state() > PM_SUSPEND_ON) {
		error = -EBUSY;
		goto out;
	}

	state = decode_suspend_state(buf, n);
	if (state < PM_SUSPEND_MAX && state > PM_SUSPEND_ON)