/*
 * 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 <linux/moduleparam.h>

#include "power.h"

const char *pm_labels[] = { "mem", "standby", "freeze", NULL };
const char *pm_states[PM_SUSPEND_MAX];

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_freeze_ops *freeze_ops;
static DECLARE_WAIT_QUEUE_HEAD(suspend_freeze_wait_head);

enum freeze_state __read_mostly suspend_freeze_state;
static DEFINE_SPINLOCK(suspend_freeze_lock);

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_state = FREEZE_STATE_NONE;
}

static void freeze_enter(void)
{
        spin_lock_irq(&suspend_freeze_lock);
        if (pm_wakeup_pending())
                goto out;

        suspend_freeze_state = FREEZE_STATE_ENTER;
        spin_unlock_irq(&suspend_freeze_lock);

        get_online_cpus();
        cpuidle_resume();

        /* Push all the CPUs into the idle loop. */
        wake_up_all_idle_cpus();
        pr_debug("PM: suspend-to-idle\n");
        /* Make the current CPU wait so it can enter the idle loop too. */
        wait_event(suspend_freeze_wait_head,
                   suspend_freeze_state == FREEZE_STATE_WAKE);
        pr_debug("PM: resume from suspend-to-idle\n");

        cpuidle_pause();
        put_online_cpus();

        spin_lock_irq(&suspend_freeze_lock);

 out:
        suspend_freeze_state = FREEZE_STATE_NONE;
        spin_unlock_irq(&suspend_freeze_lock);
}

void freeze_wake(void)
{
        unsigned long flags;

        spin_lock_irqsave(&suspend_freeze_lock, flags);
        if (suspend_freeze_state > FREEZE_STATE_NONE) {
                suspend_freeze_state = FREEZE_STATE_WAKE;
                wake_up(&suspend_freeze_wait_head);
        }
        spin_unlock_irqrestore(&suspend_freeze_lock, flags);
}
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;

void __init pm_states_init(void)
{
        /*
         * freeze state should be supported even without any suspend_ops,
         * initialize pm_states accordingly here
         */
        pm_states[PM_SUSPEND_FREEZE] = pm_labels[relative_states ? 0 : 2];
}

static int __init sleep_states_setup(char *str)
{
        relative_states = !strncmp(str, "1", 1);
        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 = 0;

        lock_system_sleep();

        suspend_ops = ops;
        for (i = PM_SUSPEND_MEM; i >= PM_SUSPEND_STANDBY; i--)
                if (valid_state(i)) {
                        pm_states[i] = pm_labels[j++];
                } else if (!relative_states) {
                        pm_states[i] = NULL;
                        j++;
                }

        pm_states[PM_SUSPEND_FREEZE] = pm_labels[j];

        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 bool sleep_state_supported(suspend_state_t state)
{
        return state == PM_SUSPEND_FREEZE || (suspend_ops && suspend_ops->enter);
}

static int platform_suspend_prepare(suspend_state_t state)
{
        return state != PM_SUSPEND_FREEZE && suspend_ops->prepare ?
                suspend_ops->prepare() : 0;
}

static int platform_suspend_prepare_late(suspend_state_t state)
{
        return state == PM_SUSPEND_FREEZE && freeze_ops && freeze_ops->prepare ?
                freeze_ops->prepare() : 0;
}

static int platform_suspend_prepare_noirq(suspend_state_t state)
{
        return state != PM_SUSPEND_FREEZE && suspend_ops->prepare_late ?
                suspend_ops->prepare_late() : 0;
}

static void platform_resume_noirq(suspend_state_t state)
{
        if (state != PM_SUSPEND_FREEZE && suspend_ops->wake)
                suspend_ops->wake();
}

static void platform_resume_early(suspend_state_t state)
{
        if (state == PM_SUSPEND_FREEZE && freeze_ops && freeze_ops->restore)
                freeze_ops->restore();
}

static void platform_resume_finish(suspend_state_t state)
{
        if (state != PM_SUSPEND_FREEZE && suspend_ops->finish)
                suspend_ops->finish();
}

static int platform_suspend_begin(suspend_state_t state)
{
        if (state == PM_SUSPEND_FREEZE && freeze_ops && freeze_ops->begin)
                return freeze_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_FREEZE && freeze_ops && freeze_ops->end)
                freeze_ops->end();
        else if (suspend_ops && suspend_ops->end)
                suspend_ops->end();
}

static void platform_recover(suspend_state_t state)
{
        if (state != PM_SUSPEND_FREEZE && suspend_ops->recover)
                suspend_ops->recover();
}

static bool platform_suspend_again(suspend_state_t state)
{
        return state != PM_SUSPEND_FREEZE && 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
        if (pm_test_level == level) {
                pr_info("suspend debug: Waiting for %d second(s).\n",
                                pm_test_delay);
                mdelay(pm_test_delay * 1000);
                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, nr_calls = 0;

        if (!sleep_state_supported(state))
                return -EPERM;

        pm_prepare_console();

        error = __pm_notifier_call_chain(PM_SUSPEND_PREPARE, -1, &nr_calls);
        if (error) {
                nr_calls--;
                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, nr_calls, NULL);
        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("PM: 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("PM: 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;

        /*
         * 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;
        }

        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;
                } else if (*wakeup) {
                        error = -EBUSY;
                }
                syscore_resume();
        }

        arch_suspend_enable_irqs();
        BUG_ON(irqs_disabled());

 Enable_cpus:
        enable_nonboot_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;

        error = platform_suspend_begin(state);
        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 && platform_suspend_again(state));

 Resume_devices:
        suspend_test_start();
        dpm_resume_end(PMSG_RESUME);
        suspend_test_finish("resume devices");
        trace_suspend_resume(TPS("resume_console"), state, true);
        resume_console();
        trace_suspend_resume(TPS("resume_console"), state, false);

 Close:
        platform_resume_end(state);
        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();
        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_warn("PM: 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(&pm_mutex))
                return -EBUSY;

        if (state == PM_SUSPEND_FREEZE)
                freeze_begin();

#ifndef CONFIG_SUSPEND_SKIP_SYNC
        trace_suspend_resume(TPS("sync_filesystems"), 0, true);
        pr_info("PM: Syncing filesystems ... ");
        sys_sync();
        pr_cont("done.\n");
        trace_suspend_resume(TPS("sync_filesystems"), 0, false);
#endif

        pr_debug("PM: Preparing system for sleep (%s)\n", pm_states[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);
        pr_debug("PM: Suspending system (%s)\n", pm_states[state]);
        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);