1 files changed, 219 insertions, 0 deletions
diff --git a/kernel/power/suspend_test.c b/kernel/power/suspend_test.c
new file mode 100644
index 000000000..b663a97f5
--- /dev/null
+++ b/kernel/power/suspend_test.c
@@ -0,0 +1,219 @@
+// 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 1;
+
+	repeat = strsep(&value, ",");
+	if (repeat) {
+		if (kstrtou32(repeat, 0, &test_repeat_count_max))
+			return 1;
+	}
+
+	for (i = PM_SUSPEND_MIN; i < PM_SUSPEND_MAX; i++)
+		if (!strcmp(pm_labels[i], suspend_type)) {
+			test_state_label = pm_labels[i];
+			return 1;
+		}
+
+	printk(warn_bad_state, suspend_type);
+	return 1;
+}
+__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);