// 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/init.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 <linux/atomic.h>
#include <linux/wait.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 unsigned int saved_gfp_count;
static gfp_t saved_gfp_mask;

void pm_restore_gfp_mask(void)
{
        WARN_ON(!mutex_is_locked(&system_transition_mutex));

        if (!saved_gfp_count || --saved_gfp_count)
                return;

        gfp_allowed_mask = saved_gfp_mask;
        saved_gfp_mask = 0;

        pm_pr_dbg("GFP mask restored\n");
}

void pm_restrict_gfp_mask(void)
{
        WARN_ON(!mutex_is_locked(&system_transition_mutex));

        if (saved_gfp_count++) {
                WARN_ON((saved_gfp_mask & ~(__GFP_IO | __GFP_FS)) != gfp_allowed_mask);
                return;
        }

        saved_gfp_mask = gfp_allowed_mask;
        gfp_allowed_mask &= ~(__GFP_IO | __GFP_FS);

        pm_pr_dbg("GFP mask restricted\n");
}

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);

#if defined(CONFIG_SUSPEND) || defined(CONFIG_HIBERNATION)
/* Wakeup events handling resolution while syncing file systems in jiffies */
#define PM_FS_SYNC_WAKEUP_RESOLUTION    5

static atomic_t pm_fs_sync_count = ATOMIC_INIT(0);
static struct workqueue_struct *pm_fs_sync_wq;
static DECLARE_WAIT_QUEUE_HEAD(pm_fs_sync_wait);

static bool pm_fs_sync_completed(void)
{
        return atomic_read(&pm_fs_sync_count) == 0;
}

static void pm_fs_sync_work_fn(struct work_struct *work)
{
        ksys_sync_helper();

        if (atomic_dec_and_test(&pm_fs_sync_count))
                wake_up(&pm_fs_sync_wait);
}
static DECLARE_WORK(pm_fs_sync_work, pm_fs_sync_work_fn);

/**
 * pm_sleep_fs_sync() - Sync file systems in an interruptible way
 *
 * Return: 0 on successful file system sync, or -EBUSY if the file system sync
 * was aborted.
 */
int pm_sleep_fs_sync(void)
{
        pm_wakeup_clear(0);

        /*
         * Take back-to-back sleeps into account by queuing a subsequent fs sync
         * only if the previous fs sync is running or is not queued. Multiple fs
         * syncs increase the likelihood of saving the latest files immediately
         * before sleep.
         */
        if (!work_pending(&pm_fs_sync_work)) {
                atomic_inc(&pm_fs_sync_count);
                queue_work(pm_fs_sync_wq, &pm_fs_sync_work);
        }

        while (!pm_fs_sync_completed()) {
                if (pm_wakeup_pending())
                        return -EBUSY;

                wait_event_timeout(pm_fs_sync_wait, pm_fs_sync_completed(),
                                   PM_FS_SYNC_WAKEUP_RESOLUTION);
        }

        return 0;
}
#endif /* CONFIG_SUSPEND || CONFIG_HIBERNATION */

/* 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 int __init pm_async_setup(char *str)
{
        if (!strcmp(str, "off"))
                pm_async_enabled = 0;
        return 1;
}
__setup("pm_async=", pm_async_setup);

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)
                mem_sleep_current = state;
        else
                error = -EINVAL;

 out:
        pm_autosleep_unlock();
        return error ? error : n;
}

power_attr(mem_sleep);

/*
 * sync_on_suspend: Sync file systems before suspend.
 *
 * show() returns whether file systems sync before suspend is enabled.
 * store() accepts 0 or 1.  0 disables file systems sync and 1 enables it.
 */
bool sync_on_suspend_enabled = !IS_ENABLED(CONFIG_SUSPEND_SKIP_SYNC);

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

static ssize_t sync_on_suspend_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;

        sync_on_suspend_enabled = !!val;
        return n;
}

power_attr(sync_on_suspend);
#endif /* CONFIG_SUSPEND */

#ifdef CONFIG_PM_SLEEP_DEBUG
int pm_test_level = TEST_NONE;

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)
{
        ssize_t count = 0;
        int level;

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

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

        return count;
}

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

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

        sleep_flags = lock_system_sleep();

        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;
                }

        unlock_system_sleep(sleep_flags);

        return error ? error : n;
}

power_attr(pm_test);
#endif /* CONFIG_PM_SLEEP_DEBUG */

#define SUSPEND_NR_STEPS        SUSPEND_RESUME
#define REC_FAILED_NUM          2

struct suspend_stats {
        unsigned int step_failures[SUSPEND_NR_STEPS];
        unsigned int success;
        unsigned int fail;
        int last_failed_dev;
        char failed_devs[REC_FAILED_NUM][40];
        int last_failed_errno;
        int errno[REC_FAILED_NUM];
        int last_failed_step;
        u64 last_hw_sleep;
        u64 total_hw_sleep;
        u64 max_hw_sleep;
        enum suspend_stat_step failed_steps[REC_FAILED_NUM];
};

static struct suspend_stats suspend_stats;
static DEFINE_MUTEX(suspend_stats_lock);

void dpm_save_failed_dev(const char *name)
{
        mutex_lock(&suspend_stats_lock);

        strscpy(suspend_stats.failed_devs[suspend_stats.last_failed_dev],
                name, sizeof(suspend_stats.failed_devs[0]));
        suspend_stats.last_failed_dev++;
        suspend_stats.last_failed_dev %= REC_FAILED_NUM;

        mutex_unlock(&suspend_stats_lock);
}

void dpm_save_failed_step(enum suspend_stat_step step)
{
        suspend_stats.step_failures[step-1]++;
        suspend_stats.failed_steps[suspend_stats.last_failed_step] = step;
        suspend_stats.last_failed_step++;
        suspend_stats.last_failed_step %= REC_FAILED_NUM;
}

void dpm_save_errno(int err)
{
        if (!err) {
                suspend_stats.success++;
                return;
        }

        suspend_stats.fail++;

        suspend_stats.errno[suspend_stats.last_failed_errno] = err;
        suspend_stats.last_failed_errno++;
        suspend_stats.last_failed_errno %= REC_FAILED_NUM;
}

void pm_report_hw_sleep_time(u64 t)
{
        suspend_stats.last_hw_sleep = t;
        suspend_stats.total_hw_sleep += t;
}
EXPORT_SYMBOL_GPL(pm_report_hw_sleep_time);

void pm_report_max_hw_sleep(u64 t)
{
        suspend_stats.max_hw_sleep = t;
}
EXPORT_SYMBOL_GPL(pm_report_max_hw_sleep);

static const char * const suspend_step_names[] = {
        [SUSPEND_WORKING] = "",
        [SUSPEND_FREEZE] = "freeze",
        [SUSPEND_PREPARE] = "prepare",
        [SUSPEND_SUSPEND] = "suspend",
        [SUSPEND_SUSPEND_LATE] = "suspend_late",
        [SUSPEND_SUSPEND_NOIRQ] = "suspend_noirq",
        [SUSPEND_RESUME_NOIRQ] = "resume_noirq",
        [SUSPEND_RESUME_EARLY] = "resume_early",
        [SUSPEND_RESUME] = "resume",
};

#define suspend_attr(_name, format_str)                         \
static ssize_t _name##_show(struct kobject *kobj,               \
                struct kobj_attribute *attr, char *buf)         \
{                                                               \
        return sysfs_emit(buf, format_str, suspend_stats._name);\
}                                                               \
static struct kobj_attribute _name = __ATTR_RO(_name)

suspend_attr(success, "%u\n");
suspend_attr(fail, "%u\n");
suspend_attr(last_hw_sleep, "%llu\n");
suspend_attr(total_hw_sleep, "%llu\n");
suspend_attr(max_hw_sleep, "%llu\n");

#define suspend_step_attr(_name, step)          \
static ssize_t _name##_show(struct kobject *kobj,               \
                struct kobj_attribute *attr, char *buf)         \
{                                                               \
        return sysfs_emit(buf, "%u\n",                          \
                       suspend_stats.step_failures[step-1]);    \
}                                                               \
static struct kobj_attribute _name = __ATTR_RO(_name)

suspend_step_attr(failed_freeze, SUSPEND_FREEZE);
suspend_step_attr(failed_prepare, SUSPEND_PREPARE);
suspend_step_attr(failed_suspend, SUSPEND_SUSPEND);
suspend_step_attr(failed_suspend_late, SUSPEND_SUSPEND_LATE);
suspend_step_attr(failed_suspend_noirq, SUSPEND_SUSPEND_NOIRQ);
suspend_step_attr(failed_resume, SUSPEND_RESUME);
suspend_step_attr(failed_resume_early, SUSPEND_RESUME_EARLY);
suspend_step_attr(failed_resume_noirq, SUSPEND_RESUME_NOIRQ);

static ssize_t last_failed_dev_show(struct kobject *kobj,
                struct kobj_attribute *attr, char *buf)
{
        int index;
        char *last_failed_dev = NULL;

        index = suspend_stats.last_failed_dev + REC_FAILED_NUM - 1;
        index %= REC_FAILED_NUM;
        last_failed_dev = suspend_stats.failed_devs[index];

        return sysfs_emit(buf, "%s\n", last_failed_dev);
}
static struct kobj_attribute last_failed_dev = __ATTR_RO(last_failed_dev);

static ssize_t last_failed_errno_show(struct kobject *kobj,
                struct kobj_attribute *attr, char *buf)
{
        int index;
        int last_failed_errno;

        index = suspend_stats.last_failed_errno + REC_FAILED_NUM - 1;
        index %= REC_FAILED_NUM;
        last_failed_errno = suspend_stats.errno[index];

        return sysfs_emit(buf, "%d\n", last_failed_errno);
}
static struct kobj_attribute last_failed_errno = __ATTR_RO(last_failed_errno);

static ssize_t last_failed_step_show(struct kobject *kobj,
                struct kobj_attribute *attr, char *buf)
{
        enum suspend_stat_step step;
        int index;

        index = suspend_stats.last_failed_step + REC_FAILED_NUM - 1;
        index %= REC_FAILED_NUM;
        step = suspend_stats.failed_steps[index];

        return sysfs_emit(buf, "%s\n", suspend_step_names[step]);
}
static struct kobj_attribute last_failed_step = __ATTR_RO(last_failed_step);

static struct attribute *suspend_attrs[] = {
        &success.attr,
        &fail.attr,
        &failed_freeze.attr,
        &failed_prepare.attr,
        &failed_suspend.attr,
        &failed_suspend_late.attr,
        &failed_suspend_noirq.attr,
        &failed_resume.attr,
        &failed_resume_early.attr,
        &failed_resume_noirq.attr,
        &last_failed_dev.attr,
        &last_failed_errno.attr,
        &last_failed_step.attr,
        &last_hw_sleep.attr,
        &total_hw_sleep.attr,
        &max_hw_sleep.attr,
        NULL,
};

static umode_t suspend_attr_is_visible(struct kobject *kobj, struct attribute *attr, int idx)
{
        if (attr != &last_hw_sleep.attr &&
            attr != &total_hw_sleep.attr &&
            attr != &max_hw_sleep.attr)
                return 0444;

#ifdef CONFIG_ACPI
        if (acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0)
                return 0444;
#endif
        return 0;
}

static const struct attribute_group suspend_attr_group = {
        .name = "suspend_stats",
        .attrs = suspend_attrs,
        .is_visible = suspend_attr_is_visible,
};

#ifdef CONFIG_DEBUG_FS
static int suspend_stats_show(struct seq_file *s, void *unused)
{
        int i, index, last_dev, last_errno, last_step;
        enum suspend_stat_step step;

        last_dev = suspend_stats.last_failed_dev + REC_FAILED_NUM - 1;
        last_dev %= REC_FAILED_NUM;
        last_errno = suspend_stats.last_failed_errno + REC_FAILED_NUM - 1;
        last_errno %= REC_FAILED_NUM;
        last_step = suspend_stats.last_failed_step + REC_FAILED_NUM - 1;
        last_step %= REC_FAILED_NUM;

        seq_printf(s, "success: %u\nfail: %u\n",
                   suspend_stats.success, suspend_stats.fail);

        for (step = SUSPEND_FREEZE; step <= SUSPEND_NR_STEPS; step++)
                seq_printf(s, "failed_%s: %u\n", suspend_step_names[step],
                           suspend_stats.step_failures[step-1]);

        seq_printf(s,   "failures:\n  last_failed_dev:\t%-s\n",
                   suspend_stats.failed_devs[last_dev]);
        for (i = 1; i < REC_FAILED_NUM; i++) {
                index = last_dev + REC_FAILED_NUM - i;
                index %= REC_FAILED_NUM;
                seq_printf(s, "\t\t\t%-s\n", suspend_stats.failed_devs[index]);
        }
        seq_printf(s,   "  last_failed_errno:\t%-d\n",
                        suspend_stats.errno[last_errno]);
        for (i = 1; i < REC_FAILED_NUM; i++) {
                index = last_errno + REC_FAILED_NUM - i;
                index %= REC_FAILED_NUM;
                seq_printf(s, "\t\t\t%-d\n", suspend_stats.errno[index]);
        }
        seq_printf(s,   "  last_failed_step:\t%-s\n",
                   suspend_step_names[suspend_stats.failed_steps[last_step]]);
        for (i = 1; i < REC_FAILED_NUM; i++) {
                index = last_step + REC_FAILED_NUM - i;
                index %= REC_FAILED_NUM;
                seq_printf(s, "\t\t\t%-s\n",
                           suspend_step_names[suspend_stats.failed_steps[index]]);
        }

        return 0;
}
DEFINE_SHOW_ATTRIBUTE(suspend_stats);

static int __init pm_debugfs_init(void)
{
        debugfs_create_file("suspend_stats", S_IFREG | S_IRUGO,
                        NULL, NULL, &suspend_stats_fops);
        return 0;
}

late_initcall(pm_debugfs_init);
#endif /* CONFIG_DEBUG_FS */

bool pm_sleep_transition_in_progress(void)
{
        return pm_suspend_in_progress() || hibernation_in_progress();
}
#endif /* CONFIG_PM_SLEEP */

#ifdef CONFIG_PM_SLEEP_DEBUG
/*
 * pm_print_times: print time taken by devices to suspend and resume.
 *
 * show() returns whether printing of suspend and resume times is enabled.
 * store() accepts 0 or 1.  0 disables printing and 1 enables it.
 */
bool pm_print_times_enabled;

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

static ssize_t pm_print_times_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_print_times_enabled = !!val;
        return n;
}

power_attr(pm_print_times);

static inline void pm_print_times_init(void)
{
        pm_print_times_enabled = initcall_debug;
}

static ssize_t pm_wakeup_irq_show(struct kobject *kobj,
                                        struct kobj_attribute *attr,
                                        char *buf)
{
        if (!pm_wakeup_irq())
                return -ENODATA;

        return sysfs_emit(buf, "%u\n", pm_wakeup_irq());
}

power_attr_ro(pm_wakeup_irq);

bool pm_debug_messages_on __read_mostly;

bool pm_debug_messages_should_print(void)
{
        return pm_debug_messages_on && pm_sleep_transition_in_progress();
}
EXPORT_SYMBOL_GPL(pm_debug_messages_should_print);

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

static ssize_t pm_debug_messages_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_debug_messages_on = !!val;
        return n;
}

power_attr(pm_debug_messages);

static int __init pm_debug_messages_setup(char *str)
{
        pm_debug_messages_on = true;
        return 1;
}
__setup("pm_debug_messages", pm_debug_messages_setup);

#else /* !CONFIG_PM_SLEEP_DEBUG */
static inline void pm_print_times_init(void) {}
#endif /* CONFIG_PM_SLEEP_DEBUG */

struct kobject *power_kobj;

/*
 * state - control system sleep states.
 *
 * show() returns available sleep state labels, which may be "mem", "standby",
 * "freeze" and "disk" (hibernation).
 * See Documentation/admin-guide/pm/sleep-states.rst for a description of
 * what they mean.
 *
 * store() accepts one of those strings, translates it into the proper
 * enumerated value, and initiates a suspend transition.
 */
static ssize_t state_show(struct kobject *kobj, struct kobj_attribute *attr,
                          char *buf)
{
        ssize_t count = 0;
#ifdef CONFIG_SUSPEND
        suspend_state_t i;

        for (i = PM_SUSPEND_MIN; i < PM_SUSPEND_MAX; i++)
                if (pm_states[i])
                        count += sysfs_emit_at(buf, count, "%s ", pm_states[i]);

#endif
        if (hibernation_available())
                count += sysfs_emit_at(buf, count, "disk ");

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

        return count;
}

static suspend_state_t decode_state(const char *buf, size_t n)
{
#ifdef CONFIG_SUSPEND
        suspend_state_t state;
#endif
        char *p;
        int len;

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

        /* Check hibernation first. */
        if (len == 4 && str_has_prefix(buf, "disk"))
                return PM_SUSPEND_MAX;

#ifdef CONFIG_SUSPEND
        for (state = PM_SUSPEND_MIN; state < PM_SUSPEND_MAX; state++) {
                const char *label = pm_states[state];

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

        return PM_SUSPEND_ON;
}

static ssize_t state_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_state(buf, n);
        if (state < PM_SUSPEND_MAX) {
                if (state == PM_SUSPEND_MEM)
                        state = mem_sleep_current;

                error = pm_suspend(state);
        } else if (state == PM_SUSPEND_MAX) {
                error = hibernate();
        } else {
                error = -EINVAL;
        }

 out:
        pm_autosleep_unlock();
        return error ? error : n;
}

power_attr(state);

#ifdef CONFIG_PM_SLEEP
/*
 * The 'wakeup_count' attribute, along with the functions defined in
 * drivers/base/power/wakeup.c, provides a means by which wakeup events can be
 * handled in a non-racy way.
 *
 * If a wakeup event occurs when the system is in a sleep state, it simply is
 * woken up.  In turn, if an event that would wake the system up from a sleep
 * state occurs when it is undergoing a transition to that sleep state, the
 * transition should be aborted.  Moreover, if such an event occurs when the
 * system is in the working state, an attempt to start a transition to the
 * given sleep state should fail during certain period after the detection of
 * the event.  Using the 'state' attribute alone is not sufficient to satisfy
 * these requirements, because a wakeup event may occur exactly when 'state'
 * is being written to and may be delivered to user space right before it is
 * frozen, so the event will remain only partially processed until the system is
 * woken up by another event.  In particular, it won't cause the transition to
 * a sleep state to be aborted.
 *
 * This difficulty may be overcome if user space uses 'wakeup_count' before
 * writing to 'state'.  It first should read from 'wakeup_count' and store
 * the read value.  Then, after carrying out its own preparations for the system
 * transition to a sleep state, it should write the stored value to
 * 'wakeup_count'.  If that fails, at least one wakeup event has occurred since
 * 'wakeup_count' was read and 'state' should not be written to.  Otherwise, it
 * is allowed to write to 'state', but the transition will be aborted if there
 * are any wakeup events detected after 'wakeup_count' was written to.
 */

static ssize_t wakeup_count_show(struct kobject *kobj,
                                struct kobj_attribute *attr,
                                char *buf)
{
        unsigned int val;

        return pm_get_wakeup_count(&val, true) ?
                sysfs_emit(buf, "%u\n", val) : -EINTR;
}

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

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

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

        error = -EINVAL;
        if (sscanf(buf, "%u", &val) == 1) {
                if (pm_save_wakeup_count(val))
                        error = n;
                else
                        pm_print_active_wakeup_sources();
        }

 out:
        pm_autosleep_unlock();
        return error;
}

power_attr(wakeup_count);

#ifdef CONFIG_PM_AUTOSLEEP
static ssize_t autosleep_show(struct kobject *kobj,
                              struct kobj_attribute *attr,
                              char *buf)
{
        suspend_state_t state = pm_autosleep_state();

        if (state == PM_SUSPEND_ON)
                return sysfs_emit(buf, "off\n");

#ifdef CONFIG_SUSPEND
        if (state < PM_SUSPEND_MAX)
                return sysfs_emit(buf, "%s\n", pm_states[state] ?
                                        pm_states[state] : "error");
#endif
#ifdef CONFIG_HIBERNATION
        return sysfs_emit(buf, "disk\n");
#else
        return sysfs_emit(buf, "error\n");
#endif
}

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

        if (state == PM_SUSPEND_ON
            && strcmp(buf, "off") && strcmp(buf, "off\n"))
                return -EINVAL;

        if (state == PM_SUSPEND_MEM)
                state = mem_sleep_current;

        error = pm_autosleep_set_state(state);
        return error ? error : n;
}

power_attr(autosleep);
#endif /* CONFIG_PM_AUTOSLEEP */

#ifdef CONFIG_PM_WAKELOCKS
static ssize_t wake_lock_show(struct kobject *kobj,
                              struct kobj_attribute *attr,
                              char *buf)
{
        return pm_show_wakelocks(buf, true);
}

static ssize_t wake_lock_store(struct kobject *kobj,
                               struct kobj_attribute *attr,
                               const char *buf, size_t n)
{
        int error = pm_wake_lock(buf);
        return error ? error : n;
}

power_attr(wake_lock);

static ssize_t wake_unlock_show(struct kobject *kobj,
                                struct kobj_attribute *attr,
                                char *buf)
{
        return pm_show_wakelocks(buf, false);
}

static ssize_t wake_unlock_store(struct kobject *kobj,
                                 struct kobj_attribute *attr,
                                 const char *buf, size_t n)
{
        int error = pm_wake_unlock(buf);
        return error ? error : n;
}

power_attr(wake_unlock);

#endif /* CONFIG_PM_WAKELOCKS */
#endif /* CONFIG_PM_SLEEP */

#ifdef CONFIG_PM_TRACE
int pm_trace_enabled;

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

static ssize_t
pm_trace_store(struct kobject *kobj, struct kobj_attribute *attr,
               const char *buf, size_t n)
{
        int val;

        if (sscanf(buf, "%d", &val) == 1) {
                pm_trace_enabled = !!val;
                if (pm_trace_enabled) {
                        pr_warn("PM: Enabling pm_trace changes system date and time during resume.\n"
                                "PM: Correct system time has to be restored manually after resume.\n");
                }
                return n;
        }
        return -EINVAL;
}

power_attr(pm_trace);

static ssize_t pm_trace_dev_match_show(struct kobject *kobj,
                                       struct kobj_attribute *attr,
                                       char *buf)
{
        return show_trace_dev_match(buf, PAGE_SIZE);
}

power_attr_ro(pm_trace_dev_match);

#endif /* CONFIG_PM_TRACE */

#ifdef CONFIG_FREEZER
static ssize_t pm_freeze_timeout_show(struct kobject *kobj,
                                      struct kobj_attribute *attr, char *buf)
{
        return sysfs_emit(buf, "%u\n", freeze_timeout_msecs);
}

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

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

        freeze_timeout_msecs = val;
        return n;
}

power_attr(pm_freeze_timeout);

#endif  /* CONFIG_FREEZER*/

#if defined(CONFIG_SUSPEND) || defined(CONFIG_HIBERNATION)
bool filesystem_freeze_enabled = false;

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

static ssize_t freeze_filesystems_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;

        filesystem_freeze_enabled = !!val;
        return n;
}

power_attr(freeze_filesystems);
#endif /* CONFIG_SUSPEND || CONFIG_HIBERNATION */

static struct attribute * g[] = {
        &state_attr.attr,
#ifdef CONFIG_PM_TRACE
        &pm_trace_attr.attr,
        &pm_trace_dev_match_attr.attr,
#endif
#ifdef CONFIG_PM_SLEEP
        &pm_async_attr.attr,
        &wakeup_count_attr.attr,
#ifdef CONFIG_SUSPEND
        &mem_sleep_attr.attr,
        &sync_on_suspend_attr.attr,
#endif
#ifdef CONFIG_PM_AUTOSLEEP
        &autosleep_attr.attr,
#endif
#ifdef CONFIG_PM_WAKELOCKS
        &wake_lock_attr.attr,
        &wake_unlock_attr.attr,
#endif
#ifdef CONFIG_PM_SLEEP_DEBUG
        &pm_test_attr.attr,
        &pm_print_times_attr.attr,
        &pm_wakeup_irq_attr.attr,
        &pm_debug_messages_attr.attr,
#endif
#endif
#ifdef CONFIG_FREEZER
        &pm_freeze_timeout_attr.attr,
#endif
#if defined(CONFIG_SUSPEND) || defined(CONFIG_HIBERNATION)
        &freeze_filesystems_attr.attr,
#endif
        NULL,
};

static const struct attribute_group attr_group = {
        .attrs = g,
};

static const struct attribute_group *attr_groups[] = {
        &attr_group,
#ifdef CONFIG_PM_SLEEP
        &suspend_attr_group,
#endif
        NULL,
};

struct workqueue_struct *pm_wq;
EXPORT_SYMBOL_GPL(pm_wq);

static int __init pm_start_workqueues(void)
{
        pm_wq = alloc_workqueue("pm", WQ_UNBOUND, 0);
        if (!pm_wq)
                return -ENOMEM;

#if defined(CONFIG_SUSPEND) || defined(CONFIG_HIBERNATION)
        pm_fs_sync_wq = alloc_ordered_workqueue("pm_fs_sync", 0);
        if (!pm_fs_sync_wq) {
                destroy_workqueue(pm_wq);
                return -ENOMEM;
        }
#endif

        return 0;
}

static int __init pm_init(void)
{
        int error = pm_start_workqueues();
        if (error)
                return error;
        hibernate_image_size_init();
        hibernate_reserved_size_init();
        pm_states_init();
        power_kobj = kobject_create_and_add("power", NULL);
        if (!power_kobj)
                return -ENOMEM;
        error = sysfs_create_groups(power_kobj, attr_groups);
        if (error)
                return error;
        pm_print_times_init();
        return pm_autosleep_init();
}

core_initcall(pm_init);