suspend_test.c

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/*
 * kernel/power/suspend_test.c - Suspend to RAM and standby test facility.
 *
 * Copyright (c) 2009 Pavel Machek <[email protected]>
 *
 * This file is released under the GPLv2.
 */

#include <linux/init.h>
#include <linux/rtc.h>

#include "power.h"

/*
 * We test the system suspend code by setting an RTC wakealarm a short
 * time in the future, then suspending.  Suspending the devices won't
 * normally take long ... some systems only need a few milliseconds.
 *
 * The time it takes is system-specific though, so when we test this
 * during system bootup we allow a LOT of time.
 */
#define TEST_SUSPEND_SECONDS    10

static unsigned long suspend_test_start_time;

void suspend_test_start(void)
{
    /* FIXME Use better timebase than "jiffies", ideally a clocksource.
     * What we want is a hardware counter that will work correctly even
     * during the irqs-are-off stages of the suspend/resume cycle...
     */
    suspend_test_start_time = jiffies;
}

void suspend_test_finish(const char *label)
{
    long nj = jiffies - suspend_test_start_time;
    unsigned msec;

    msec = jiffies_to_msecs(abs(nj));
    pr_info("PM: %s took %d.%03d seconds\n", label,
            msec / 1000, msec % 1000);

    /* Warning on suspend means the RTC alarm period needs to be
     * larger -- the system was sooo slooowwww to suspend that the
     * alarm (should have) fired before the system went to sleep!
     *
     * Warning on either suspend or resume also means the system
     * has some performance issues.  The stack dump of a WARN_ON
     * is more likely to get the right attention than a printk...
     */
    WARN(msec > (TEST_SUSPEND_SECONDS * 1000),
         "Component: %s, time: %u\n", label, msec);
}

/*
 * To test system suspend, we need a hands-off mechanism to resume the
 * system.  RTCs wake alarms are a common self-contained mechanism.
 */

static void __init test_wakealarm(struct rtc_device *rtc, suspend_state_t state)
{
    static char err_readtime[] __initdata =
        KERN_ERR "PM: can't read %s time, err %d\n";
    static char err_wakealarm [] __initdata =
        KERN_ERR "PM: can't set %s wakealarm, err %d\n";
    static char err_suspend[] __initdata =
        KERN_ERR "PM: suspend test failed, error %d\n";
    static char info_test[] __initdata =
        KERN_INFO "PM: test RTC wakeup from '%s' suspend\n";

    unsigned long       now;
    struct rtc_wkalrm   alm;
    int         status;

    /* this may fail if the RTC hasn't been initialized */
    status = rtc_read_time(rtc, &alm.time);
    if (status < 0) {
        printk(err_readtime, dev_name(&rtc->dev), status);
        return;
    }
    rtc_tm_to_time(&alm.time, &now);

    memset(&alm, 0, sizeof alm);
    rtc_time_to_tm(now + TEST_SUSPEND_SECONDS, &alm.time);
    alm.enabled = true;

    status = rtc_set_alarm(rtc, &alm);
    if (status < 0) {
        printk(err_wakealarm, dev_name(&rtc->dev), status);
        return;
    }

    if (state == PM_SUSPEND_MEM) {
        printk(info_test, pm_states[state]);
        status = pm_suspend(state);
        if (status == -ENODEV)
            state = PM_SUSPEND_STANDBY;
    }
    if (state == PM_SUSPEND_STANDBY) {
        printk(info_test, pm_states[state]);
        status = pm_suspend(state);
    }
    if (status < 0)
        printk(err_suspend, status);

    /* Some platforms can't detect that the alarm triggered the
     * wakeup, or (accordingly) disable it after it afterwards.
     * It's supposed to give oneshot behavior; cope.
     */
    alm.enabled = false;
    rtc_set_alarm(rtc, &alm);
}

static int __init has_wakealarm(struct device *dev, void *name_ptr)
{
    struct rtc_device *candidate = to_rtc_device(dev);

    if (!candidate->ops->set_alarm)
        return 0;
    if (!device_may_wakeup(candidate->dev.parent))
        return 0;

    *(const char **)name_ptr = dev_name(dev);
    return 1;
}

/*
 * Kernel options like "test_suspend=mem" force suspend/resume sanity tests
 * at startup time.  They're normally disabled, for faster boot and because
 * we can't know which states really work on this particular system.
 */
static suspend_state_t test_state __initdata = PM_SUSPEND_ON;

static char warn_bad_state[] __initdata =
    KERN_WARNING "PM: can't test '%s' suspend state\n";

static int __init setup_test_suspend(char *value)
{
    unsigned i;

    /* "=mem" ==> "mem" */
    value++;
    for (i = 0; i < PM_SUSPEND_MAX; i++) {
        if (!pm_states[i])
            continue;
        if (strcmp(pm_states[i], value) != 0)
            continue;
        test_state = (__force suspend_state_t) i;
        return 0;
    }
    printk(warn_bad_state, value);
    return 0;
}
__setup("test_suspend", setup_test_suspend);

static int __init test_suspend(void)
{
    static char     warn_no_rtc[] __initdata =
        KERN_WARNING "PM: no wakealarm-capable RTC driver is ready\n";

    char            *pony = NULL;
    struct rtc_device   *rtc = NULL;

    /* PM is initialized by now; is that state testable? */
    if (test_state == PM_SUSPEND_ON)
        goto done;
    if (!valid_state(test_state)) {
        printk(warn_bad_state, pm_states[test_state]);
        goto done;
    }

    /* RTCs have initialized by now too ... can we use one? */
    class_find_device(rtc_class, NULL, &pony, has_wakealarm);
    if (pony)
        rtc = rtc_class_open(pony);
    if (!rtc) {
        printk(warn_no_rtc);
        goto done;
    }

    /* go for it */
    test_wakealarm(rtc, test_state);
    rtc_class_close(rtc);
done:
    return 0;
}
late_initcall(test_suspend);