uio: documentation fixups

[zen-stable.git] / kernel / power / hibernate.c

/*
 * kernel/power/hibernate.c - Hibernation (a.k.a suspend-to-disk) support.
 *
 * Copyright (c) 2003 Patrick Mochel
 * Copyright (c) 2003 Open Source Development Lab
 * Copyright (c) 2004 Pavel Machek <pavel@ucw.cz>
 * Copyright (c) 2009 Rafael J. Wysocki, Novell Inc.
 *
 * This file is released under the GPLv2.
 */

#include <linux/export.h>
#include <linux/suspend.h>
#include <linux/syscalls.h>
#include <linux/reboot.h>
#include <linux/string.h>
#include <linux/device.h>
#include <linux/async.h>
#include <linux/kmod.h>
#include <linux/delay.h>
#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/pm.h>
#include <linux/console.h>
#include <linux/cpu.h>
#include <linux/freezer.h>
#include <linux/gfp.h>
#include <linux/syscore_ops.h>
#include <scsi/scsi_scan.h>

#include "power.h"


static int nocompress;
static int noresume;
static int resume_wait;
static int resume_delay;
static char resume_file[256] = CONFIG_PM_STD_PARTITION;
dev_t swsusp_resume_device;
sector_t swsusp_resume_block;
int in_suspend __nosavedata;

enum {
        HIBERNATION_INVALID,
        HIBERNATION_PLATFORM,
        HIBERNATION_TEST,
        HIBERNATION_TESTPROC,
        HIBERNATION_SHUTDOWN,
        HIBERNATION_REBOOT,
        /* keep last */
        __HIBERNATION_AFTER_LAST
};
#define HIBERNATION_MAX (__HIBERNATION_AFTER_LAST-1)
#define HIBERNATION_FIRST (HIBERNATION_INVALID + 1)

static int hibernation_mode = HIBERNATION_SHUTDOWN;

static const struct platform_hibernation_ops *hibernation_ops;

/**
 * hibernation_set_ops - Set the global hibernate operations.
 * @ops: Hibernation operations to use in subsequent hibernation transitions.
 */
void hibernation_set_ops(const struct platform_hibernation_ops *ops)
{
        if (ops && !(ops->begin && ops->end &&  ops->pre_snapshot
            && ops->prepare && ops->finish && ops->enter && ops->pre_restore
            && ops->restore_cleanup && ops->leave)) {
                WARN_ON(1);
                return;
        }
        mutex_lock(&pm_mutex);
        hibernation_ops = ops;
        if (ops)
                hibernation_mode = HIBERNATION_PLATFORM;
        else if (hibernation_mode == HIBERNATION_PLATFORM)
                hibernation_mode = HIBERNATION_SHUTDOWN;

        mutex_unlock(&pm_mutex);
}

static bool entering_platform_hibernation;

bool system_entering_hibernation(void)
{
        return entering_platform_hibernation;
}
EXPORT_SYMBOL(system_entering_hibernation);

#ifdef CONFIG_PM_DEBUG
static void hibernation_debug_sleep(void)
{
        printk(KERN_INFO "hibernation debug: Waiting for 5 seconds.\n");
        mdelay(5000);
}

static int hibernation_testmode(int mode)
{
        if (hibernation_mode == mode) {
                hibernation_debug_sleep();
                return 1;
        }
        return 0;
}

static int hibernation_test(int level)
{
        if (pm_test_level == level) {
                hibernation_debug_sleep();
                return 1;
        }
        return 0;
}
#else /* !CONFIG_PM_DEBUG */
static int hibernation_testmode(int mode) { return 0; }
static int hibernation_test(int level) { return 0; }
#endif /* !CONFIG_PM_DEBUG */

/**
 * platform_begin - Call platform to start hibernation.
 * @platform_mode: Whether or not to use the platform driver.
 */
static int platform_begin(int platform_mode)
{
        return (platform_mode && hibernation_ops) ?
                hibernation_ops->begin() : 0;
}

/**
 * platform_end - Call platform to finish transition to the working state.
 * @platform_mode: Whether or not to use the platform driver.
 */
static void platform_end(int platform_mode)
{
        if (platform_mode && hibernation_ops)
                hibernation_ops->end();
}

/**
 * platform_pre_snapshot - Call platform to prepare the machine for hibernation.
 * @platform_mode: Whether or not to use the platform driver.
 *
 * Use the platform driver to prepare the system for creating a hibernate image,
 * if so configured, and return an error code if that fails.
 */

static int platform_pre_snapshot(int platform_mode)
{
        return (platform_mode && hibernation_ops) ?
                hibernation_ops->pre_snapshot() : 0;
}

/**
 * platform_leave - Call platform to prepare a transition to the working state.
 * @platform_mode: Whether or not to use the platform driver.
 *
 * Use the platform driver prepare to prepare the machine for switching to the
 * normal mode of operation.
 *
 * This routine is called on one CPU with interrupts disabled.
 */
static void platform_leave(int platform_mode)
{
        if (platform_mode && hibernation_ops)
                hibernation_ops->leave();
}

/**
 * platform_finish - Call platform to switch the system to the working state.
 * @platform_mode: Whether or not to use the platform driver.
 *
 * Use the platform driver to switch the machine to the normal mode of
 * operation.
 *
 * This routine must be called after platform_prepare().
 */
static void platform_finish(int platform_mode)
{
        if (platform_mode && hibernation_ops)
                hibernation_ops->finish();
}

/**
 * platform_pre_restore - Prepare for hibernate image restoration.
 * @platform_mode: Whether or not to use the platform driver.
 *
 * Use the platform driver to prepare the system for resume from a hibernation
 * image.
 *
 * If the restore fails after this function has been called,
 * platform_restore_cleanup() must be called.
 */
static int platform_pre_restore(int platform_mode)
{
        return (platform_mode && hibernation_ops) ?
                hibernation_ops->pre_restore() : 0;
}

/**
 * platform_restore_cleanup - Switch to the working state after failing restore.
 * @platform_mode: Whether or not to use the platform driver.
 *
 * Use the platform driver to switch the system to the normal mode of operation
 * after a failing restore.
 *
 * If platform_pre_restore() has been called before the failing restore, this
 * function must be called too, regardless of the result of
 * platform_pre_restore().
 */
static void platform_restore_cleanup(int platform_mode)
{
        if (platform_mode && hibernation_ops)
                hibernation_ops->restore_cleanup();
}

/**
 * platform_recover - Recover from a failure to suspend devices.
 * @platform_mode: Whether or not to use the platform driver.
 */
static void platform_recover(int platform_mode)
{
        if (platform_mode && hibernation_ops && hibernation_ops->recover)
                hibernation_ops->recover();
}

/**
 * swsusp_show_speed - Print time elapsed between two events during hibernation.
 * @start: Starting event.
 * @stop: Final event.
 * @nr_pages: Number of memory pages processed between @start and @stop.
 * @msg: Additional diagnostic message to print.
 */
void swsusp_show_speed(struct timeval *start, struct timeval *stop,
                        unsigned nr_pages, char *msg)
{
        s64 elapsed_centisecs64;
        int centisecs;
        int k;
        int kps;

        elapsed_centisecs64 = timeval_to_ns(stop) - timeval_to_ns(start);
        do_div(elapsed_centisecs64, NSEC_PER_SEC / 100);
        centisecs = elapsed_centisecs64;
        if (centisecs == 0)
                centisecs = 1;  /* avoid div-by-zero */
        k = nr_pages * (PAGE_SIZE / 1024);
        kps = (k * 100) / centisecs;
        printk(KERN_INFO "PM: %s %d kbytes in %d.%02d seconds (%d.%02d MB/s)\n",
                        msg, k,
                        centisecs / 100, centisecs % 100,
                        kps / 1000, (kps % 1000) / 10);
}

/**
 * create_image - Create a hibernation image.
 * @platform_mode: Whether or not to use the platform driver.
 *
 * Execute device drivers' .freeze_noirq() callbacks, create a hibernation image
 * and execute the drivers' .thaw_noirq() callbacks.
 *
 * Control reappears in this routine after the subsequent restore.
 */
static int create_image(int platform_mode)
{
        int error;

        error = dpm_suspend_noirq(PMSG_FREEZE);
        if (error) {
                printk(KERN_ERR "PM: Some devices failed to power down, "
                        "aborting hibernation\n");
                return error;
        }

        error = platform_pre_snapshot(platform_mode);
        if (error || hibernation_test(TEST_PLATFORM))
                goto Platform_finish;

        error = disable_nonboot_cpus();
        if (error || hibernation_test(TEST_CPUS)
            || hibernation_testmode(HIBERNATION_TEST))
                goto Enable_cpus;

        local_irq_disable();

        error = syscore_suspend();
        if (error) {
                printk(KERN_ERR "PM: Some system devices failed to power down, "
                        "aborting hibernation\n");
                goto Enable_irqs;
        }

        if (hibernation_test(TEST_CORE) || pm_wakeup_pending())
                goto Power_up;

        in_suspend = 1;
        save_processor_state();
        error = swsusp_arch_suspend();
        if (error)
                printk(KERN_ERR "PM: Error %d creating hibernation image\n",
                        error);
        /* Restore control flow magically appears here */
        restore_processor_state();
        if (!in_suspend) {
                events_check_enabled = false;
                platform_leave(platform_mode);
        }

 Power_up:
        syscore_resume();

 Enable_irqs:
        local_irq_enable();

 Enable_cpus:
        enable_nonboot_cpus();

 Platform_finish:
        platform_finish(platform_mode);

        dpm_resume_noirq(in_suspend ?
                (error ? PMSG_RECOVER : PMSG_THAW) : PMSG_RESTORE);

        return error;
}

/**
 * hibernation_snapshot - Quiesce devices and create a hibernation image.
 * @platform_mode: If set, use platform driver to prepare for the transition.
 *
 * This routine must be called with pm_mutex held.
 */
int hibernation_snapshot(int platform_mode)
{
        pm_message_t msg = PMSG_RECOVER;
        int error;

        error = platform_begin(platform_mode);
        if (error)
                goto Close;

        /* Preallocate image memory before shutting down devices. */
        error = hibernate_preallocate_memory();
        if (error)
                goto Close;

        error = freeze_kernel_threads();
        if (error)
                goto Close;

        error = dpm_prepare(PMSG_FREEZE);
        if (error)
                goto Complete_devices;

        suspend_console();
        pm_restrict_gfp_mask();
        error = dpm_suspend(PMSG_FREEZE);
        if (error)
                goto Recover_platform;

        if (hibernation_test(TEST_DEVICES))
                goto Recover_platform;

        error = create_image(platform_mode);
        /*
         * Control returns here (1) after the image has been created or the
         * image creation has failed and (2) after a successful restore.
         */

 Resume_devices:
        /* We may need to release the preallocated image pages here. */
        if (error || !in_suspend)
                swsusp_free();

        msg = in_suspend ? (error ? PMSG_RECOVER : PMSG_THAW) : PMSG_RESTORE;
        dpm_resume(msg);

        if (error || !in_suspend)
                pm_restore_gfp_mask();

        resume_console();

 Complete_devices:
        dpm_complete(msg);

 Close:
        platform_end(platform_mode);
        return error;

 Recover_platform:
        platform_recover(platform_mode);
        goto Resume_devices;
}

/**
 * resume_target_kernel - Restore system state from a hibernation image.
 * @platform_mode: Whether or not to use the platform driver.
 *
 * Execute device drivers' .freeze_noirq() callbacks, restore the contents of
 * highmem that have not been restored yet from the image and run the low-level
 * code that will restore the remaining contents of memory and switch to the
 * just restored target kernel.
 */
static int resume_target_kernel(bool platform_mode)
{
        int error;

        error = dpm_suspend_noirq(PMSG_QUIESCE);
        if (error) {
                printk(KERN_ERR "PM: Some devices failed to power down, "
                        "aborting resume\n");
                return error;
        }

        error = platform_pre_restore(platform_mode);
        if (error)
                goto Cleanup;

        error = disable_nonboot_cpus();
        if (error)
                goto Enable_cpus;

        local_irq_disable();

        error = syscore_suspend();
        if (error)
                goto Enable_irqs;

        save_processor_state();
        error = restore_highmem();
        if (!error) {
                error = swsusp_arch_resume();
                /*
                 * The code below is only ever reached in case of a failure.
                 * Otherwise, execution continues at the place where
                 * swsusp_arch_suspend() was called.
                 */
                BUG_ON(!error);
                /*
                 * This call to restore_highmem() reverts the changes made by
                 * the previous one.
                 */
                restore_highmem();
        }
        /*
         * The only reason why swsusp_arch_resume() can fail is memory being
         * very tight, so we have to free it as soon as we can to avoid
         * subsequent failures.
         */
        swsusp_free();
        restore_processor_state();
        touch_softlockup_watchdog();

        syscore_resume();

 Enable_irqs:
        local_irq_enable();

 Enable_cpus:
        enable_nonboot_cpus();

 Cleanup:
        platform_restore_cleanup(platform_mode);

        dpm_resume_noirq(PMSG_RECOVER);

        return error;
}

/**
 * hibernation_restore - Quiesce devices and restore from a hibernation image.
 * @platform_mode: If set, use platform driver to prepare for the transition.
 *
 * This routine must be called with pm_mutex held.  If it is successful, control
 * reappears in the restored target kernel in hibernation_snapshot().
 */
int hibernation_restore(int platform_mode)
{
        int error;

        pm_prepare_console();
        suspend_console();
        pm_restrict_gfp_mask();
        error = dpm_suspend_start(PMSG_QUIESCE);
        if (!error) {
                error = resume_target_kernel(platform_mode);
                dpm_resume_end(PMSG_RECOVER);
        }
        pm_restore_gfp_mask();
        resume_console();
        pm_restore_console();
        return error;
}

/**
 * hibernation_platform_enter - Power off the system using the platform driver.
 */
int hibernation_platform_enter(void)
{
        int error;

        if (!hibernation_ops)
                return -ENOSYS;

        /*
         * We have cancelled the power transition by running
         * hibernation_ops->finish() before saving the image, so we should let
         * the firmware know that we're going to enter the sleep state after all
         */
        error = hibernation_ops->begin();
        if (error)
                goto Close;

        entering_platform_hibernation = true;
        suspend_console();
        error = dpm_suspend_start(PMSG_HIBERNATE);
        if (error) {
                if (hibernation_ops->recover)
                        hibernation_ops->recover();
                goto Resume_devices;
        }

        error = dpm_suspend_noirq(PMSG_HIBERNATE);
        if (error)
                goto Resume_devices;

        error = hibernation_ops->prepare();
        if (error)
                goto Platform_finish;

        error = disable_nonboot_cpus();
        if (error)
                goto Platform_finish;

        local_irq_disable();
        syscore_suspend();
        if (pm_wakeup_pending()) {
                error = -EAGAIN;
                goto Power_up;
        }

        hibernation_ops->enter();
        /* We should never get here */
        while (1);

 Power_up:
        syscore_resume();
        local_irq_enable();
        enable_nonboot_cpus();

 Platform_finish:
        hibernation_ops->finish();

        dpm_resume_noirq(PMSG_RESTORE);

 Resume_devices:
        entering_platform_hibernation = false;
        dpm_resume_end(PMSG_RESTORE);
        resume_console();

 Close:
        hibernation_ops->end();

        return error;
}

/**
 * power_down - Shut the machine down for hibernation.
 *
 * Use the platform driver, if configured, to put the system into the sleep
 * state corresponding to hibernation, or try to power it off or reboot,
 * depending on the value of hibernation_mode.
 */
static void power_down(void)
{
        switch (hibernation_mode) {
        case HIBERNATION_TEST:
        case HIBERNATION_TESTPROC:
                break;
        case HIBERNATION_REBOOT:
                kernel_restart(NULL);
                break;
        case HIBERNATION_PLATFORM:
                hibernation_platform_enter();
        case HIBERNATION_SHUTDOWN:
                kernel_power_off();
                break;
        }
        kernel_halt();
        /*
         * Valid image is on the disk, if we continue we risk serious data
         * corruption after resume.
         */
        printk(KERN_CRIT "PM: Please power down manually\n");
        while(1);
}

static int prepare_processes(void)
{
        int error = 0;

        if (freeze_processes()) {
                error = -EBUSY;
                thaw_processes();
        }
        return error;
}

/**
 * hibernate - Carry out system hibernation, including saving the image.
 */
int hibernate(void)
{
        int error;

        mutex_lock(&pm_mutex);
        /* The snapshot device should not be opened while we're running */
        if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
                error = -EBUSY;
                goto Unlock;
        }

        pm_prepare_console();
        error = pm_notifier_call_chain(PM_HIBERNATION_PREPARE);
        if (error)
                goto Exit;

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

        /* Allocate memory management structures */
        error = create_basic_memory_bitmaps();
        if (error)
                goto Exit;

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

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

        if (hibernation_test(TEST_FREEZER))
                goto Thaw;

        if (hibernation_testmode(HIBERNATION_TESTPROC))
                goto Thaw;

        error = hibernation_snapshot(hibernation_mode == HIBERNATION_PLATFORM);
        if (error)
                goto Thaw;

        if (in_suspend) {
                unsigned int flags = 0;

                if (hibernation_mode == HIBERNATION_PLATFORM)
                        flags |= SF_PLATFORM_MODE;
                if (nocompress)
                        flags |= SF_NOCOMPRESS_MODE;
                else
                        flags |= SF_CRC32_MODE;

                pr_debug("PM: writing image.\n");
                error = swsusp_write(flags);
                swsusp_free();
                if (!error)
                        power_down();
                in_suspend = 0;
                pm_restore_gfp_mask();
        } else {
                pr_debug("PM: Image restored successfully.\n");
        }

 Thaw:
        thaw_processes();
 Finish:
        free_basic_memory_bitmaps();
        usermodehelper_enable();
 Exit:
        pm_notifier_call_chain(PM_POST_HIBERNATION);
        pm_restore_console();
        atomic_inc(&snapshot_device_available);
 Unlock:
        mutex_unlock(&pm_mutex);
        return error;
}


/**
 * software_resume - Resume from a saved hibernation image.
 *
 * This routine is called as a late initcall, when all devices have been
 * discovered and initialized already.
 *
 * The image reading code is called to see if there is a hibernation image
 * available for reading.  If that is the case, devices are quiesced and the
 * contents of memory is restored from the saved image.
 *
 * If this is successful, control reappears in the restored target kernel in
 * hibernation_snaphot() which returns to hibernate().  Otherwise, the routine
 * attempts to recover gracefully and make the kernel return to the normal mode
 * of operation.
 */
static int software_resume(void)
{
        int error;
        unsigned int flags;

        /*
         * If the user said "noresume".. bail out early.
         */
        if (noresume)
                return 0;

        /*
         * name_to_dev_t() below takes a sysfs buffer mutex when sysfs
         * is configured into the kernel. Since the regular hibernate
         * trigger path is via sysfs which takes a buffer mutex before
         * calling hibernate functions (which take pm_mutex) this can
         * cause lockdep to complain about a possible ABBA deadlock
         * which cannot happen since we're in the boot code here and
         * sysfs can't be invoked yet. Therefore, we use a subclass
         * here to avoid lockdep complaining.
         */
        mutex_lock_nested(&pm_mutex, SINGLE_DEPTH_NESTING);

        if (swsusp_resume_device)
                goto Check_image;

        if (!strlen(resume_file)) {
                error = -ENOENT;
                goto Unlock;
        }

        pr_debug("PM: Checking hibernation image partition %s\n", resume_file);

        if (resume_delay) {
                printk(KERN_INFO "Waiting %dsec before reading resume device...\n",
                        resume_delay);
                ssleep(resume_delay);
        }

        /* Check if the device is there */
        swsusp_resume_device = name_to_dev_t(resume_file);
        if (!swsusp_resume_device) {
                /*
                 * Some device discovery might still be in progress; we need
                 * to wait for this to finish.
                 */
                wait_for_device_probe();

                if (resume_wait) {
                        while ((swsusp_resume_device = name_to_dev_t(resume_file)) == 0)
                                msleep(10);
                        async_synchronize_full();
                }

                /*
                 * We can't depend on SCSI devices being available after loading
                 * one of their modules until scsi_complete_async_scans() is
                 * called and the resume device usually is a SCSI one.
                 */
                scsi_complete_async_scans();

                swsusp_resume_device = name_to_dev_t(resume_file);
                if (!swsusp_resume_device) {
                        error = -ENODEV;
                        goto Unlock;
                }
        }

 Check_image:
        pr_debug("PM: Hibernation image partition %d:%d present\n",
                MAJOR(swsusp_resume_device), MINOR(swsusp_resume_device));

        pr_debug("PM: Looking for hibernation image.\n");
        error = swsusp_check();
        if (error)
                goto Unlock;

        /* The snapshot device should not be opened while we're running */
        if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
                error = -EBUSY;
                swsusp_close(FMODE_READ);
                goto Unlock;
        }

        pm_prepare_console();
        error = pm_notifier_call_chain(PM_RESTORE_PREPARE);
        if (error)
                goto close_finish;

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

        error = create_basic_memory_bitmaps();
        if (error)
                goto close_finish;

        pr_debug("PM: Preparing processes for restore.\n");
        error = prepare_processes();
        if (error) {
                swsusp_close(FMODE_READ);
                goto Done;
        }

        pr_debug("PM: Loading hibernation image.\n");

        error = swsusp_read(&flags);
        swsusp_close(FMODE_READ);
        if (!error)
                hibernation_restore(flags & SF_PLATFORM_MODE);

        printk(KERN_ERR "PM: Failed to load hibernation image, recovering.\n");
        swsusp_free();
        thaw_processes();
 Done:
        free_basic_memory_bitmaps();
        usermodehelper_enable();
 Finish:
        pm_notifier_call_chain(PM_POST_RESTORE);
        pm_restore_console();
        atomic_inc(&snapshot_device_available);
        /* For success case, the suspend path will release the lock */
 Unlock:
        mutex_unlock(&pm_mutex);
        pr_debug("PM: Hibernation image not present or could not be loaded.\n");
        return error;
close_finish:
        swsusp_close(FMODE_READ);
        goto Finish;
}

late_initcall(software_resume);


static const char * const hibernation_modes[] = {
        [HIBERNATION_PLATFORM]  = "platform",
        [HIBERNATION_SHUTDOWN]  = "shutdown",
        [HIBERNATION_REBOOT]    = "reboot",
        [HIBERNATION_TEST]      = "test",
        [HIBERNATION_TESTPROC]  = "testproc",
};

/*
 * /sys/power/disk - Control hibernation mode.
 *
 * Hibernation can be handled in several ways.  There are a few different ways
 * to put the system into the sleep state: using the platform driver (e.g. ACPI
 * or other hibernation_ops), powering it off or rebooting it (for testing
 * mostly), or using one of the two available test modes.
 *
 * The sysfs file /sys/power/disk provides an interface for selecting the
 * hibernation mode to use.  Reading from this file causes the available modes
 * to be printed.  There are 5 modes that can be supported:
 *
 *      'platform'
 *      'shutdown'
 *      'reboot'
 *      'test'
 *      'testproc'
 *
 * If a platform hibernation driver is in use, 'platform' will be supported
 * and will be used by default.  Otherwise, 'shutdown' will be used by default.
 * The selected option (i.e. the one corresponding to the current value of
 * hibernation_mode) is enclosed by a square bracket.
 *
 * To select a given hibernation mode it is necessary to write the mode's
 * string representation (as returned by reading from /sys/power/disk) back
 * into /sys/power/disk.
 */

static ssize_t disk_show(struct kobject *kobj, struct kobj_attribute *attr,
                         char *buf)
{
        int i;
        char *start = buf;

        for (i = HIBERNATION_FIRST; i <= HIBERNATION_MAX; i++) {
                if (!hibernation_modes[i])
                        continue;
                switch (i) {
                case HIBERNATION_SHUTDOWN:
                case HIBERNATION_REBOOT:
                case HIBERNATION_TEST:
                case HIBERNATION_TESTPROC:
                        break;
                case HIBERNATION_PLATFORM:
                        if (hibernation_ops)
                                break;
                        /* not a valid mode, continue with loop */
                        continue;
                }
                if (i == hibernation_mode)
                        buf += sprintf(buf, "[%s] ", hibernation_modes[i]);
                else
                        buf += sprintf(buf, "%s ", hibernation_modes[i]);
        }
        buf += sprintf(buf, "\n");
        return buf-start;
}

static ssize_t disk_store(struct kobject *kobj, struct kobj_attribute *attr,
                          const char *buf, size_t n)
{
        int error = 0;
        int i;
        int len;
        char *p;
        int mode = HIBERNATION_INVALID;

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

        mutex_lock(&pm_mutex);
        for (i = HIBERNATION_FIRST; i <= HIBERNATION_MAX; i++) {
                if (len == strlen(hibernation_modes[i])
                    && !strncmp(buf, hibernation_modes[i], len)) {
                        mode = i;
                        break;
                }
        }
        if (mode != HIBERNATION_INVALID) {
                switch (mode) {
                case HIBERNATION_SHUTDOWN:
                case HIBERNATION_REBOOT:
                case HIBERNATION_TEST:
                case HIBERNATION_TESTPROC:
                        hibernation_mode = mode;
                        break;
                case HIBERNATION_PLATFORM:
                        if (hibernation_ops)
                                hibernation_mode = mode;
                        else
                                error = -EINVAL;
                }
        } else
                error = -EINVAL;

        if (!error)
                pr_debug("PM: Hibernation mode set to '%s'\n",
                         hibernation_modes[mode]);
        mutex_unlock(&pm_mutex);
        return error ? error : n;
}

power_attr(disk);

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

static ssize_t resume_store(struct kobject *kobj, struct kobj_attribute *attr,
                            const char *buf, size_t n)
{
        unsigned int maj, min;
        dev_t res;
        int ret = -EINVAL;

        if (sscanf(buf, "%u:%u", &maj, &min) != 2)
                goto out;

        res = MKDEV(maj,min);
        if (maj != MAJOR(res) || min != MINOR(res))
                goto out;

        mutex_lock(&pm_mutex);
        swsusp_resume_device = res;
        mutex_unlock(&pm_mutex);
        printk(KERN_INFO "PM: Starting manual resume from disk\n");
        noresume = 0;
        software_resume();
        ret = n;
 out:
        return ret;
}

power_attr(resume);

static ssize_t image_size_show(struct kobject *kobj, struct kobj_attribute *attr,
                               char *buf)
{
        return sprintf(buf, "%lu\n", image_size);
}

static ssize_t image_size_store(struct kobject *kobj, struct kobj_attribute *attr,
                                const char *buf, size_t n)
{
        unsigned long size;

        if (sscanf(buf, "%lu", &size) == 1) {
                image_size = size;
                return n;
        }

        return -EINVAL;
}

power_attr(image_size);

static ssize_t reserved_size_show(struct kobject *kobj,
                                  struct kobj_attribute *attr, char *buf)
{
        return sprintf(buf, "%lu\n", reserved_size);
}

static ssize_t reserved_size_store(struct kobject *kobj,
                                   struct kobj_attribute *attr,
                                   const char *buf, size_t n)
{
        unsigned long size;

        if (sscanf(buf, "%lu", &size) == 1) {
                reserved_size = size;
                return n;
        }

        return -EINVAL;
}

power_attr(reserved_size);

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


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


static int __init pm_disk_init(void)
{
        return sysfs_create_group(power_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 resume_offset_setup(char *str)
{
        unsigned long long offset;

        if (noresume)
                return 1;

        if (sscanf(str, "%llu", &offset) == 1)
                swsusp_resume_block = offset;

        return 1;
}

static int __init hibernate_setup(char *str)
{
        if (!strncmp(str, "noresume", 8))
                noresume = 1;
        else if (!strncmp(str, "nocompress", 10))
                nocompress = 1;
        return 1;
}

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

static int __init resumewait_setup(char *str)
{
        resume_wait = 1;
        return 1;
}

static int __init resumedelay_setup(char *str)
{
        resume_delay = simple_strtoul(str, NULL, 0);
        return 1;
}

__setup("noresume", noresume_setup);
__setup("resume_offset=", resume_offset_setup);
__setup("resume=", resume_setup);
__setup("hibernate=", hibernate_setup);
__setup("resumewait", resumewait_setup);
__setup("resumedelay=", resumedelay_setup);