// 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 <linux/fs.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)
{
        unsigned int sleep_flags;

        sleep_flags = lock_system_sleep();
        s2idle_ops = ops;
        unlock_system_sleep(sleep_flags);
}

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);

        /*
         * The correctness of the code below depends on the number of online
         * CPUs being stable, but CPUs cannot be taken offline or put online
         * while it is running.
         *
         * The s2idle_lock must be acquired before the pending wakeup check to
         * prevent pm_system_wakeup() from running as a whole between that check
         * and the subsequent s2idle_state update in which case a wakeup event
         * would get lost.
         */
        raw_spin_lock_irq(&s2idle_lock);
        if (pm_wakeup_pending())
                goto out;

        s2idle_state = S2IDLE_STATE_ENTER;
        raw_spin_unlock_irq(&s2idle_lock);

        /* 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);

        /*
         * Kick all CPUs to ensure that they resume their timers and restore
         * consistent system state.
         */
        wake_up_all_idle_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;
                }

                if (s2idle_ops && s2idle_ops->check)
                        s2idle_ops->check();

                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)
{
        /*
         * The PM_SUSPEND_STANDBY and PM_SUSPEND_MEM states require low-level
         * support and need to be valid to the low-level implementation.
         *
         * No ->valid() or ->enter() callback implies that none are valid.
         */
        return suspend_ops && suspend_ops->valid && suspend_ops->valid(state) &&
                suspend_ops->enter;
}

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;
                        mem_sleep_current = 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)
{
        unsigned int sleep_flags;

        sleep_flags = 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(sleep_flags);
}
EXPORT_SYMBOL_GPL(suspend_set_ops);

/**
 * suspend_valid_only_mem - Generic memory-only valid callback.
 * @state: Target system sleep state.
 *
 * 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 ||
               (valid_state(state) && !cxl_mem_active());
}

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
        int i;

        if (pm_test_level == level) {
                pr_info("suspend debug: Waiting for %d second(s).\n",
                                pm_test_delay);
                for (i = 0; i < pm_test_delay && !pm_wakeup_pending(); i++) {
                        if (level > TEST_CORE)
                                msleep(1000);
                        else
                                mdelay(1000);
                }
                return 1;
        }
#endif /* !CONFIG_PM_DEBUG */
        return 0;
}

/**
 * suspend_prepare - Prepare for entering system sleep state.
 * @state: Target 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;

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

        dpm_save_failed_step(SUSPEND_FREEZE);
        filesystems_thaw();
        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 = pm_sleep_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:
        pm_sleep_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;

        console_suspend_all();
        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("console_resume_all"), state, true);
        console_resume_all();
        trace_suspend_resume(TPS("console_resume_all"), 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();
        filesystems_thaw();
        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);

                error = pm_sleep_fs_sync();
                if (error)
                        goto Unlock;

                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]);
        error = suspend_devices_and_enter(state);

 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);
        dpm_save_errno(error);
        pr_info("suspend exit\n");
        return error;
}
EXPORT_SYMBOL(pm_suspend);