/*
 * kernel/power/main.c - PM subsystem core functionality.
 *
 * Copyright (c) 2003 Patrick Mochel
 * Copyright (c) 2003 Open Source Development Lab
 * 
 * This file is released under the GPLv2
 *
 */

#include <linux/suspend.h>
#include <linux/kobject.h>
#include <linux/string.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/pm.h>


#include "power.h"

DECLARE_MUTEX(pm_sem);

struct pm_ops * pm_ops = NULL;
suspend_disk_method_t pm_disk_mode = PM_DISK_SHUTDOWN;

/**
 *      pm_set_ops - Set the global power method table. 
 *      @ops:   Pointer to ops structure.
 */

void pm_set_ops(struct pm_ops * ops)
{
        down(&pm_sem);
        pm_ops = ops;
        up(&pm_sem);
}


/**
 *      suspend_prepare - Do prep work before entering low-power state.
 *      @state:         State we're entering.
 *
 *      This is common code that is called for each state that we're 
 *      entering. Allocate a console, stop all processes, then make sure
 *      the platform can enter the requested state.
 */

static int suspend_prepare(suspend_state_t state)
{
        int error = 0;

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

        pm_prepare_console();

        if (freeze_processes()) {
                error = -EAGAIN;
                goto Thaw;
        }

        if (pm_ops->prepare) {
                if ((error = pm_ops->prepare(state)))
                        goto Thaw;
        }

        if ((error = device_suspend(PMSG_SUSPEND)))
                goto Finish;
        return 0;
 Finish:
        if (pm_ops->finish)
                pm_ops->finish(state);
 Thaw:
        thaw_processes();
        pm_restore_console();
        return error;
}


static int suspend_enter(suspend_state_t state)
{
        int error = 0;
        unsigned long flags;

        local_irq_save(flags);

        if ((error = device_power_down(PMSG_SUSPEND)))
                goto Done;
        error = pm_ops->enter(state);
        device_power_up();
 Done:
        local_irq_restore(flags);
        return error;
}


/**
 *      suspend_finish - Do final work before exiting suspend sequence.
 *      @state:         State we're coming out of.
 *
 *      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(suspend_state_t state)
{
        device_resume();
        if (pm_ops && pm_ops->finish)
                pm_ops->finish(state);
        thaw_processes();
        pm_restore_console();
}




char * pm_states[] = {
        [PM_SUSPEND_STANDBY]    = "standby",
        [PM_SUSPEND_MEM]        = "mem",
        [PM_SUSPEND_DISK]       = "disk",
        NULL,
};


/**
 *      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).
 */

static int enter_state(suspend_state_t state)
{
        int error;

        if (down_trylock(&pm_sem))
                return -EBUSY;

        if (state == PM_SUSPEND_DISK) {
                error = pm_suspend_disk();
                goto Unlock;
        }

        /* Suspend is hard to get right on SMP. */
        if (num_online_cpus() != 1) {
                error = -EPERM;
                goto Unlock;
        }

        pr_debug("PM: Preparing system for suspend\n");
        if ((error = suspend_prepare(state)))
                goto Unlock;

        pr_debug("PM: Entering state.\n");
        error = suspend_enter(state);

        pr_debug("PM: Finishing up.\n");
        suspend_finish(state);
 Unlock:
        up(&pm_sem);
        return error;
}

/*
 * This is main interface to the outside world. It needs to be
 * called from process context.
 */
int software_suspend(void)
{
        return enter_state(PM_SUSPEND_DISK);
}


/**
 *      pm_suspend - Externally visible function for suspending system.
 *      @state:         Enumarted 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;
}



decl_subsys(power,NULL,NULL);


/**
 *      state - control system power state.
 *
 *      show() returns what states are supported, which is hard-coded to
 *      'standby' (Power-On Suspend), 'mem' (Suspend-to-RAM), and
 *      'disk' (Suspend-to-Disk).
 *
 *      store() accepts one of those strings, translates it into the 
 *      proper enumerated value, and initiates a suspend transition.
 */

static ssize_t state_show(struct subsystem * subsys, char * buf)
{
        int i;
        char * s = buf;

        for (i = 0; i < PM_SUSPEND_MAX; i++) {
                if (pm_states[i])
                        s += sprintf(s,"%s ",pm_states[i]);
        }
        s += sprintf(s,"\n");
        return (s - buf);
}

static ssize_t state_store(struct subsystem * subsys, const char * buf, size_t n)
{
        suspend_state_t state = PM_SUSPEND_STANDBY;
        char ** s;
        char *p;
        int error;
        int len;

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

        for (s = &pm_states[state]; state < PM_SUSPEND_MAX; s++, state++) {
                if (*s && !strncmp(buf, *s, len))
                        break;
        }
        if (*s)
                error = enter_state(state);
        else
                error = -EINVAL;
        return error ? error : n;
}

power_attr(state);

static struct attribute * g[] = {
        &state_attr.attr,
        NULL,
};

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


static int __init pm_init(void)
{
        int error = subsystem_register(&power_subsys);
        if (!error)
                error = sysfs_create_group(&power_subsys.kset.kobj,&attr_group);
        return error;
}

core_initcall(pm_init);