// SPDX-License-Identifier: GPL-2.0-only
/*
 * kernel/power/suspend_test.c - Suspend to RAM and standby test facility.
 *
 * Copyright (c) 2009 Pavel Machek <pavel@ucw.cz>
 */

#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;
static u32 test_repeat_count_max = 1;
static u32 test_repeat_count_current;

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";

        time64_t                now;
        struct rtc_wkalrm       alm;
        int                     status;

        /* this may fail if the RTC hasn't been initialized */
repeat:
        status = rtc_read_time(rtc, &alm.time);
        if (status < 0) {
                printk(err_readtime, dev_name(&rtc->dev), status);
                return;
        }
        now = rtc_tm_to_time64(&alm.time);

        memset(&alm, 0, sizeof alm);
        rtc_time64_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)
                        state = PM_SUSPEND_TO_IDLE;
        }
        if (state == PM_SUSPEND_TO_IDLE) {
                printk(info_test, pm_states[state]);
                status = pm_suspend(state);
        }

        if (status < 0)
                printk(err_suspend, status);

        test_repeat_count_current++;
        if (test_repeat_count_current < test_repeat_count_max)
                goto repeat;

        /* 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 (!test_bit(RTC_FEATURE_ALARM, candidate->features))
                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 const char *test_state_label __initdata;

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

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

        /* example : "=mem[,N]" ==> "mem[,N]" */
        value++;
        suspend_type = strsep(&value, ",");
        if (!suspend_type)
                return 0;

        repeat = strsep(&value, ",");
        if (repeat) {
                if (kstrtou32(repeat, 0, &test_repeat_count_max))
                        return 0;
        }

        for (i = PM_SUSPEND_MIN; i < PM_SUSPEND_MAX; i++)
                if (!strcmp(pm_labels[i], suspend_type)) {
                        test_state_label = pm_labels[i];
                        return 0;
                }

        printk(warn_bad_state, suspend_type);
        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;
        suspend_state_t test_state;

        /* PM is initialized by now; is that state testable? */
        if (!test_state_label)
                return 0;

        for (test_state = PM_SUSPEND_MIN; test_state < PM_SUSPEND_MAX; test_state++) {
                const char *state_label = pm_states[test_state];

                if (state_label && !strcmp(test_state_label, state_label))
                        break;
        }
        if (test_state == PM_SUSPEND_MAX) {
                printk(warn_bad_state, test_state_label);
                return 0;
        }

        /* 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));
                put_device(dev);
        }
        if (!rtc) {
                printk(warn_no_rtc);
                return 0;
        }

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