linux/kernel/power/suspend_test.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * kernel/power/suspend_test.c - Suspend to RAM and standby test facility.
   4 *
   5 * Copyright (c) 2009 Pavel Machek <pavel@ucw.cz>
   6 */
   7
   8#include <linux/init.h>
   9#include <linux/rtc.h>
  10
  11#include "power.h"
  12
  13/*
  14 * We test the system suspend code by setting an RTC wakealarm a short
  15 * time in the future, then suspending.  Suspending the devices won't
  16 * normally take long ... some systems only need a few milliseconds.
  17 *
  18 * The time it takes is system-specific though, so when we test this
  19 * during system bootup we allow a LOT of time.
  20 */
  21#define TEST_SUSPEND_SECONDS    10
  22
  23static unsigned long suspend_test_start_time;
  24static u32 test_repeat_count_max = 1;
  25static u32 test_repeat_count_current;
  26
  27void suspend_test_start(void)
  28{
  29        /* FIXME Use better timebase than "jiffies", ideally a clocksource.
  30         * What we want is a hardware counter that will work correctly even
  31         * during the irqs-are-off stages of the suspend/resume cycle...
  32         */
  33        suspend_test_start_time = jiffies;
  34}
  35
  36void suspend_test_finish(const char *label)
  37{
  38        long nj = jiffies - suspend_test_start_time;
  39        unsigned msec;
  40
  41        msec = jiffies_to_msecs(abs(nj));
  42        pr_info("PM: %s took %d.%03d seconds\n", label,
  43                        msec / 1000, msec % 1000);
  44
  45        /* Warning on suspend means the RTC alarm period needs to be
  46         * larger -- the system was sooo slooowwww to suspend that the
  47         * alarm (should have) fired before the system went to sleep!
  48         *
  49         * Warning on either suspend or resume also means the system
  50         * has some performance issues.  The stack dump of a WARN_ON
  51         * is more likely to get the right attention than a printk...
  52         */
  53        WARN(msec > (TEST_SUSPEND_SECONDS * 1000),
  54             "Component: %s, time: %u\n", label, msec);
  55}
  56
  57/*
  58 * To test system suspend, we need a hands-off mechanism to resume the
  59 * system.  RTCs wake alarms are a common self-contained mechanism.
  60 */
  61
  62static void __init test_wakealarm(struct rtc_device *rtc, suspend_state_t state)
  63{
  64        static char err_readtime[] __initdata =
  65                KERN_ERR "PM: can't read %s time, err %d\n";
  66        static char err_wakealarm [] __initdata =
  67                KERN_ERR "PM: can't set %s wakealarm, err %d\n";
  68        static char err_suspend[] __initdata =
  69                KERN_ERR "PM: suspend test failed, error %d\n";
  70        static char info_test[] __initdata =
  71                KERN_INFO "PM: test RTC wakeup from '%s' suspend\n";
  72
  73        time64_t                now;
  74        struct rtc_wkalrm       alm;
  75        int                     status;
  76
  77        /* this may fail if the RTC hasn't been initialized */
  78repeat:
  79        status = rtc_read_time(rtc, &alm.time);
  80        if (status < 0) {
  81                printk(err_readtime, dev_name(&rtc->dev), status);
  82                return;
  83        }
  84        now = rtc_tm_to_time64(&alm.time);
  85
  86        memset(&alm, 0, sizeof alm);
  87        rtc_time64_to_tm(now + TEST_SUSPEND_SECONDS, &alm.time);
  88        alm.enabled = true;
  89
  90        status = rtc_set_alarm(rtc, &alm);
  91        if (status < 0) {
  92                printk(err_wakealarm, dev_name(&rtc->dev), status);
  93                return;
  94        }
  95
  96        if (state == PM_SUSPEND_MEM) {
  97                printk(info_test, pm_states[state]);
  98                status = pm_suspend(state);
  99                if (status == -ENODEV)
 100                        state = PM_SUSPEND_STANDBY;
 101        }
 102        if (state == PM_SUSPEND_STANDBY) {
 103                printk(info_test, pm_states[state]);
 104                status = pm_suspend(state);
 105                if (status < 0)
 106                        state = PM_SUSPEND_TO_IDLE;
 107        }
 108        if (state == PM_SUSPEND_TO_IDLE) {
 109                printk(info_test, pm_states[state]);
 110                status = pm_suspend(state);
 111        }
 112
 113        if (status < 0)
 114                printk(err_suspend, status);
 115
 116        test_repeat_count_current++;
 117        if (test_repeat_count_current < test_repeat_count_max)
 118                goto repeat;
 119
 120        /* Some platforms can't detect that the alarm triggered the
 121         * wakeup, or (accordingly) disable it after it afterwards.
 122         * It's supposed to give oneshot behavior; cope.
 123         */
 124        alm.enabled = false;
 125        rtc_set_alarm(rtc, &alm);
 126}
 127
 128static int __init has_wakealarm(struct device *dev, const void *data)
 129{
 130        struct rtc_device *candidate = to_rtc_device(dev);
 131
 132        if (!candidate->ops->set_alarm)
 133                return 0;
 134        if (!device_may_wakeup(candidate->dev.parent))
 135                return 0;
 136
 137        return 1;
 138}
 139
 140/*
 141 * Kernel options like "test_suspend=mem" force suspend/resume sanity tests
 142 * at startup time.  They're normally disabled, for faster boot and because
 143 * we can't know which states really work on this particular system.
 144 */
 145static const char *test_state_label __initdata;
 146
 147static char warn_bad_state[] __initdata =
 148        KERN_WARNING "PM: can't test '%s' suspend state\n";
 149
 150static int __init setup_test_suspend(char *value)
 151{
 152        int i;
 153        char *repeat;
 154        char *suspend_type;
 155
 156        /* example : "=mem[,N]" ==> "mem[,N]" */
 157        value++;
 158        suspend_type = strsep(&value, ",");
 159        if (!suspend_type)
 160                return 0;
 161
 162        repeat = strsep(&value, ",");
 163        if (repeat) {
 164                if (kstrtou32(repeat, 0, &test_repeat_count_max))
 165                        return 0;
 166        }
 167
 168        for (i = PM_SUSPEND_MIN; i < PM_SUSPEND_MAX; i++)
 169                if (!strcmp(pm_labels[i], suspend_type)) {
 170                        test_state_label = pm_labels[i];
 171                        return 0;
 172                }
 173
 174        printk(warn_bad_state, suspend_type);
 175        return 0;
 176}
 177__setup("test_suspend", setup_test_suspend);
 178
 179static int __init test_suspend(void)
 180{
 181        static char             warn_no_rtc[] __initdata =
 182                KERN_WARNING "PM: no wakealarm-capable RTC driver is ready\n";
 183
 184        struct rtc_device       *rtc = NULL;
 185        struct device           *dev;
 186        suspend_state_t test_state;
 187
 188        /* PM is initialized by now; is that state testable? */
 189        if (!test_state_label)
 190                return 0;
 191
 192        for (test_state = PM_SUSPEND_MIN; test_state < PM_SUSPEND_MAX; test_state++) {
 193                const char *state_label = pm_states[test_state];
 194
 195                if (state_label && !strcmp(test_state_label, state_label))
 196                        break;
 197        }
 198        if (test_state == PM_SUSPEND_MAX) {
 199                printk(warn_bad_state, test_state_label);
 200                return 0;
 201        }
 202
 203        /* RTCs have initialized by now too ... can we use one? */
 204        dev = class_find_device(rtc_class, NULL, NULL, has_wakealarm);
 205        if (dev) {
 206                rtc = rtc_class_open(dev_name(dev));
 207                put_device(dev);
 208        }
 209        if (!rtc) {
 210                printk(warn_no_rtc);
 211                return 0;
 212        }
 213
 214        /* go for it */
 215        test_wakealarm(rtc, test_state);
 216        rtc_class_close(rtc);
 217        return 0;
 218}
 219late_initcall(test_suspend);
 220