[PATCH] swsusp: fix comments

[linux-2.6/cjktty.git] / kernel / power / disk.c

/*
 * kernel/power/disk.c - Suspend-to-disk support.
 *
 * Copyright (c) 2003 Patrick Mochel
 * Copyright (c) 2003 Open Source Development Lab
 * Copyright (c) 2004 Pavel Machek <pavel@suse.cz>
 *
 * This file is released under the GPLv2.
 *
 */

#include <linux/suspend.h>
#include <linux/syscalls.h>
#include <linux/reboot.h>
#include <linux/string.h>
#include <linux/device.h>
#include <linux/delay.h>
#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/pm.h>

#include "power.h"


extern suspend_disk_method_t pm_disk_mode;

extern int swsusp_suspend(void);
extern int swsusp_write(void);
extern int swsusp_check(void);
extern int swsusp_read(void);
extern void swsusp_close(void);
extern int swsusp_resume(void);
extern int swsusp_free(void);


static int noresume = 0;
char resume_file[256] = CONFIG_PM_STD_PARTITION;
dev_t swsusp_resume_device;

/**
 *      power_down - Shut machine down for hibernate.
 *      @mode:          Suspend-to-disk mode
 *
 *      Use the platform driver, if configured so, and return gracefully if it
 *      fails.
 *      Otherwise, try to power off and reboot. If they fail, halt the machine,
 *      there ain't no turning back.
 */

static void power_down(suspend_disk_method_t mode)
{
        int error = 0;

        switch(mode) {
        case PM_DISK_PLATFORM:
                kernel_power_off_prepare();
                error = pm_ops->enter(PM_SUSPEND_DISK);
                break;
        case PM_DISK_SHUTDOWN:
                kernel_power_off();
                break;
        case PM_DISK_REBOOT:
                kernel_restart(NULL);
                break;
        }
        kernel_halt();
        /* Valid image is on the disk, if we continue we risk serious data corruption
           after resume. */
        printk(KERN_CRIT "Please power me down manually\n");
        while(1);
}


static int in_suspend __nosavedata = 0;


/**
 *      free_some_memory -  Try to free as much memory as possible
 *
 *      ... but do not OOM-kill anyone
 *
 *      Notice: all userland should be stopped at this point, or
 *      livelock is possible.
 */

static void free_some_memory(void)
{
        unsigned int i = 0;
        unsigned int tmp;
        unsigned long pages = 0;
        char *p = "-\\|/";

        printk("Freeing memory...  ");
        while ((tmp = shrink_all_memory(10000))) {
                pages += tmp;
                printk("\b%c", p[i]);
                i++;
                if (i > 3)
                        i = 0;
        }
        printk("\bdone (%li pages freed)\n", pages);
}


static inline void platform_finish(void)
{
        if (pm_disk_mode == PM_DISK_PLATFORM) {
                if (pm_ops && pm_ops->finish)
                        pm_ops->finish(PM_SUSPEND_DISK);
        }
}

static int prepare_processes(void)
{
        int error;

        pm_prepare_console();
        sys_sync();
        disable_nonboot_cpus();

        if (freeze_processes()) {
                error = -EBUSY;
                goto thaw;
        }

        if (pm_disk_mode == PM_DISK_PLATFORM) {
                if (pm_ops && pm_ops->prepare) {
                        if ((error = pm_ops->prepare(PM_SUSPEND_DISK)))
                                goto thaw;
                }
        }

        /* Free memory before shutting down devices. */
        free_some_memory();
        return 0;
thaw:
        thaw_processes();
        enable_nonboot_cpus();
        pm_restore_console();
        return error;
}

static void unprepare_processes(void)
{
        platform_finish();
        thaw_processes();
        enable_nonboot_cpus();
        pm_restore_console();
}

/**
 *      pm_suspend_disk - The granpappy of power management.
 *
 *      If we're going through the firmware, then get it over with quickly.
 *
 *      If not, then call swsusp to do its thing, then figure out how
 *      to power down the system.
 */

int pm_suspend_disk(void)
{
        int error;

        error = prepare_processes();
        if (error)
                return error;

        error = device_suspend(PMSG_FREEZE);
        if (error) {
                printk("Some devices failed to suspend\n");
                unprepare_processes();
                return error;
        }

        pr_debug("PM: snapshotting memory.\n");
        in_suspend = 1;
        if ((error = swsusp_suspend()))
                goto Done;

        if (in_suspend) {
                pr_debug("PM: writing image.\n");
                error = swsusp_write();
                if (!error)
                        power_down(pm_disk_mode);
                else {
                /* swsusp_write can not fail in device_resume,
                   no need to do second device_resume */
                        swsusp_free();
                        unprepare_processes();
                        return error;
                }
        } else
                pr_debug("PM: Image restored successfully.\n");

        swsusp_free();
 Done:
        device_resume();
        unprepare_processes();
        return error;
}


/**
 *      software_resume - Resume from a saved image.
 *
 *      Called as a late_initcall (so all devices are discovered and
 *      initialized), we call swsusp to see if we have a saved image or not.
 *      If so, we quiesce devices, the restore the saved image. We will
 *      return above (in pm_suspend_disk() ) if everything goes well.
 *      Otherwise, we fail gracefully and return to the normally
 *      scheduled program.
 *
 */

static int software_resume(void)
{
        int error;

        down(&pm_sem);
        if (!swsusp_resume_device) {
                if (!strlen(resume_file)) {
                        up(&pm_sem);
                        return -ENOENT;
                }
                swsusp_resume_device = name_to_dev_t(resume_file);
                pr_debug("swsusp: Resume From Partition %s\n", resume_file);
        } else {
                pr_debug("swsusp: Resume From Partition %d:%d\n",
                         MAJOR(swsusp_resume_device), MINOR(swsusp_resume_device));
        }

        if (noresume) {
                /**
                 * FIXME: If noresume is specified, we need to find the partition
                 * and reset it back to normal swap space.
                 */
                up(&pm_sem);
                return 0;
        }

        pr_debug("PM: Checking swsusp image.\n");

        if ((error = swsusp_check()))
                goto Done;

        pr_debug("PM: Preparing processes for restore.\n");

        if ((error = prepare_processes())) {
                swsusp_close();
                goto Done;
        }

        pr_debug("PM: Reading swsusp image.\n");

        if ((error = swsusp_read()))
                goto Cleanup;

        pr_debug("PM: Preparing devices for restore.\n");

        if ((error = device_suspend(PMSG_FREEZE))) {
                printk("Some devices failed to suspend\n");
                goto Free;
        }

        mb();

        pr_debug("PM: Restoring saved image.\n");
        swsusp_resume();
        pr_debug("PM: Restore failed, recovering.n");
        device_resume();
 Free:
        swsusp_free();
 Cleanup:
        unprepare_processes();
 Done:
        /* For success case, the suspend path will release the lock */
        up(&pm_sem);
        pr_debug("PM: Resume from disk failed.\n");
        return 0;
}

late_initcall(software_resume);


static char * pm_disk_modes[] = {
        [PM_DISK_FIRMWARE]      = "firmware",
        [PM_DISK_PLATFORM]      = "platform",
        [PM_DISK_SHUTDOWN]      = "shutdown",
        [PM_DISK_REBOOT]        = "reboot",
};

/**
 *      disk - Control suspend-to-disk mode
 *
 *      Suspend-to-disk can be handled in several ways. The greatest
 *      distinction is who writes memory to disk - the firmware or the OS.
 *      If the firmware does it, we assume that it also handles suspending
 *      the system.
 *      If the OS does it, then we have three options for putting the system
 *      to sleep - using the platform driver (e.g. ACPI or other PM registers),
 *      powering off the system or rebooting the system (for testing).
 *
 *      The system will support either 'firmware' or 'platform', and that is
 *      known a priori (and encoded in pm_ops). But, the user may choose
 *      'shutdown' or 'reboot' as alternatives.
 *
 *      show() will display what the mode is currently set to.
 *      store() will accept one of
 *
 *      'firmware'
 *      'platform'
 *      'shutdown'
 *      'reboot'
 *
 *      It will only change to 'firmware' or 'platform' if the system
 *      supports it (as determined from pm_ops->pm_disk_mode).
 */

static ssize_t disk_show(struct subsystem * subsys, char * buf)
{
        return sprintf(buf, "%s\n", pm_disk_modes[pm_disk_mode]);
}


static ssize_t disk_store(struct subsystem * s, const char * buf, size_t n)
{
        int error = 0;
        int i;
        int len;
        char *p;
        suspend_disk_method_t mode = 0;

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

        down(&pm_sem);
        for (i = PM_DISK_FIRMWARE; i < PM_DISK_MAX; i++) {
                if (!strncmp(buf, pm_disk_modes[i], len)) {
                        mode = i;
                        break;
                }
        }
        if (mode) {
                if (mode == PM_DISK_SHUTDOWN || mode == PM_DISK_REBOOT)
                        pm_disk_mode = mode;
                else {
                        if (pm_ops && pm_ops->enter &&
                            (mode == pm_ops->pm_disk_mode))
                                pm_disk_mode = mode;
                        else
                                error = -EINVAL;
                }
        } else
                error = -EINVAL;

        pr_debug("PM: suspend-to-disk mode set to '%s'\n",
                 pm_disk_modes[mode]);
        up(&pm_sem);
        return error ? error : n;
}

power_attr(disk);

static ssize_t resume_show(struct subsystem * subsys, char *buf)
{
        return sprintf(buf,"%d:%d\n", MAJOR(swsusp_resume_device),
                       MINOR(swsusp_resume_device));
}

static ssize_t resume_store(struct subsystem * subsys, const char * buf, size_t n)
{
        int len;
        char *p;
        unsigned int maj, min;
        int error = -EINVAL;
        dev_t res;

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

        if (sscanf(buf, "%u:%u", &maj, &min) == 2) {
                res = MKDEV(maj,min);
                if (maj == MAJOR(res) && min == MINOR(res)) {
                        down(&pm_sem);
                        swsusp_resume_device = res;
                        up(&pm_sem);
                        printk("Attempting manual resume\n");
                        noresume = 0;
                        software_resume();
                }
        }

        return error >= 0 ? n : error;
}

power_attr(resume);

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


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


static int __init pm_disk_init(void)
{
        return sysfs_create_group(&power_subsys.kset.kobj,&attr_group);
}

core_initcall(pm_disk_init);


static int __init resume_setup(char *str)
{
        if (noresume)
                return 1;

        strncpy( resume_file, str, 255 );
        return 1;
}

static int __init noresume_setup(char *str)
{
        noresume = 1;
        return 1;
}

__setup("noresume", noresume_setup);
__setup("resume=", resume_setup);