linux/kernel/power/suspend_test.c at master · fabgithub/linux · GitHub

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* kernel/power/suspend_test.c - Suspend to RAM and standby test facility.

* 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, const void *data)

{

struct rtc_device *candidate = to_rtc_device(dev);

if (!candidate->ops->set_alarm)

return 0;

if (!device_may_wakeup(candidate->dev.parent))

return 0;

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";

struct rtc_device *rtc = NULL;

struct device *dev;

/* 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? */

dev = class_find_device(rtc_class, NULL, NULL, has_wakealarm);

if (dev)

rtc = rtc_class_open(dev_name(dev));

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);

linux/kernel/power/suspend_test.c at master · fabgithub/linux · GitHub

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