/*
 * 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/syscalls.h>

#include "power.h"

const char *const pm_states[PM_SUSPEND_MAX] = {
        [PM_SUSPEND_STANDBY]    = "standby",
        [PM_SUSPEND_MEM]        = "mem",
};

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);
}

bool valid_state(suspend_state_t state)
{
        /*
         * All states need lowlevel support and need to be valid to the lowlevel
         * implementation, no valid callback implies that none are valid.
         */
        return suspend_ops && suspend_ops->valid && suspend_ops->valid(state);
}

/**
 * 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;
}

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

/**
 *      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;

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

        pm_prepare_console();

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

        error = usermodehelper_disable();
        if (error)
                goto Finish;

        error = suspend_freeze_processes();
        if (!error)
                return 0;

        suspend_thaw_processes();
        usermodehelper_enable();
 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;

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

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

        if (suspend_ops->prepare_late) {
                error = suspend_ops->prepare_late();
                if (error)
                        goto Power_up_devices;
        }

        if (suspend_test(TEST_PLATFORM))
                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 = sysdev_suspend(PMSG_SUSPEND);
        if (!error) {
                if (!suspend_test(TEST_CORE))
                        error = suspend_ops->enter(state);
                sysdev_resume();
        }

        arch_suspend_enable_irqs();
        BUG_ON(irqs_disabled());

 Enable_cpus:
        enable_nonboot_cpus();

 Platform_wake:
        if (suspend_ops->wake)
                suspend_ops->wake();

 Power_up_devices:
        dpm_resume_noirq(PMSG_RESUME);

 Platfrom_finish:
        if (suspend_ops->finish)
                suspend_ops->finish();

        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;

        if (!suspend_ops)
                return -ENOSYS;

        if (suspend_ops->begin) {
                error = suspend_ops->begin(state);
                if (error)
                        goto Close;
        }
        suspend_console();
        suspend_test_start();
        error = dpm_suspend_start(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;

        suspend_enter(state);

 Resume_devices:
        suspend_test_start();
        dpm_resume_end(PMSG_RESUME);
        suspend_test_finish("resume devices");
        resume_console();
 Close:
        if (suspend_ops->end)
                suspend_ops->end();
        return error;

 Recover_platform:
        if (suspend_ops->recover)
                suspend_ops->recover();
        goto Resume_devices;
}

/**
 *      suspend_finish - Do final work before exiting suspend sequence.
 *
 *      Call platform code to clean up, restart processes, and free the
 *      console that we've allocated. This is not called for suspend-to-disk.
 */
static void suspend_finish(void)
{
        suspend_thaw_processes();
        usermodehelper_enable();
        pm_notifier_call_chain(PM_POST_SUSPEND);
        pm_restore_console();
}

/**
 *      enter_state - Do common work of entering low-power state.
 *      @state:         pm_state structure for state we're entering.
 *
 *      Make sure we're the only ones trying to enter a sleep state. Fail
 *      if someone has beat us to it, since we don't want anything weird to
 *      happen when we wake up.
 *      Then, do the setup for suspend, enter the state, and cleaup (after
 *      we've woken up).
 */
int enter_state(suspend_state_t state)
{
        int error;

        if (!valid_state(state))
                return -ENODEV;

        if (!mutex_trylock(&pm_mutex))
                return -EBUSY;

        printk(KERN_INFO "PM: Syncing filesystems ... ");
        sys_sync();
        printk("done.\n");

        pr_debug("PM: Preparing system for %s sleep\n", pm_states[state]);
        error = suspend_prepare();
        if (error)
                goto Unlock;

        if (suspend_test(TEST_FREEZER))
                goto Finish;

        pr_debug("PM: Entering %s sleep\n", pm_states[state]);
        error = suspend_devices_and_enter(state);

 Finish:
        pr_debug("PM: Finishing wakeup.\n");
        suspend_finish();
 Unlock:
        mutex_unlock(&pm_mutex);
        return error;
}

/**
 *      pm_suspend - Externally visible function for suspending system.
 *      @state:         Enumerated value of state to enter.
 *
 *      Determine whether or not value is within range, get state
 *      structure, and enter (above).
 */
int pm_suspend(suspend_state_t state)
{
        if (state > PM_SUSPEND_ON && state <= PM_SUSPEND_MAX)
                return enter_state(state);
        return -EINVAL;
}
EXPORT_SYMBOL(pm_suspend);