1/*
  2 * kernel/power/suspend_test.c - Suspend to RAM and standby test facility.
  3 *
  4 * Copyright (c) 2009 Pavel Machek <pavel@ucw.cz>
  5 *
  6 * This file is released under the GPLv2.
  7 */
  8
  9#include <linux/init.h>
 10#include <linux/rtc.h>
 11
 12#include "power.h"
 13
 14/*
 15 * We test the system suspend code by setting an RTC wakealarm a short
 16 * time in the future, then suspending.  Suspending the devices won't
 17 * normally take long ... some systems only need a few milliseconds.
 18 *
 19 * The time it takes is system-specific though, so when we test this
 20 * during system bootup we allow a LOT of time.
 21 */
 22#define TEST_SUSPEND_SECONDS	10
 23
 24static unsigned long suspend_test_start_time;
 25
 26void suspend_test_start(void)
 27{
 28	/* FIXME Use better timebase than "jiffies", ideally a clocksource.
 29	 * What we want is a hardware counter that will work correctly even
 30	 * during the irqs-are-off stages of the suspend/resume cycle...
 31	 */
 32	suspend_test_start_time = jiffies;
 33}
 34
 35void suspend_test_finish(const char *label)
 36{
 37	long nj = jiffies - suspend_test_start_time;
 38	unsigned msec;
 39
 40	msec = jiffies_to_msecs(abs(nj));
 41	pr_info("PM: %s took %d.%03d seconds\n", label,
 42			msec / 1000, msec % 1000);
 43
 44	/* Warning on suspend means the RTC alarm period needs to be
 45	 * larger -- the system was sooo slooowwww to suspend that the
 46	 * alarm (should have) fired before the system went to sleep!
 47	 *
 48	 * Warning on either suspend or resume also means the system
 49	 * has some performance issues.  The stack dump of a WARN_ON
 50	 * is more likely to get the right attention than a printk...
 51	 */
 52	WARN(msec > (TEST_SUSPEND_SECONDS * 1000),
 53	     "Component: %s, time: %u\n", label, msec);
 54}
 55
 56/*
 57 * To test system suspend, we need a hands-off mechanism to resume the
 58 * system.  RTCs wake alarms are a common self-contained mechanism.
 59 */
 60
 61static void __init test_wakealarm(struct rtc_device *rtc, suspend_state_t state)
 62{
 63	static char err_readtime[] __initdata =
 64		KERN_ERR "PM: can't read %s time, err %d\n";
 65	static char err_wakealarm [] __initdata =
 66		KERN_ERR "PM: can't set %s wakealarm, err %d\n";
 67	static char err_suspend[] __initdata =
 68		KERN_ERR "PM: suspend test failed, error %d\n";
 69	static char info_test[] __initdata =
 70		KERN_INFO "PM: test RTC wakeup from '%s' suspend\n";
 71
 72	unsigned long		now;
 73	struct rtc_wkalrm	alm;
 74	int			status;
 75
 76	/* this may fail if the RTC hasn't been initialized */
 77	status = rtc_read_time(rtc, &alm.time);
 78	if (status < 0) {
 79		printk(err_readtime, dev_name(&rtc->dev), status);
 80		return;
 81	}
 82	rtc_tm_to_time(&alm.time, &now);
 83
 84	memset(&alm, 0, sizeof alm);
 85	rtc_time_to_tm(now + TEST_SUSPEND_SECONDS, &alm.time);
 86	alm.enabled = true;
 87
 88	status = rtc_set_alarm(rtc, &alm);
 89	if (status < 0) {
 90		printk(err_wakealarm, dev_name(&rtc->dev), status);
 91		return;
 92	}
 93
 94	if (state == PM_SUSPEND_MEM) {
 95		printk(info_test, pm_states[state]);
 96		status = pm_suspend(state);
 97		if (status == -ENODEV)
 98			state = PM_SUSPEND_STANDBY;
 99	}
100	if (state == PM_SUSPEND_STANDBY) {
101		printk(info_test, pm_states[state]);
102		status = pm_suspend(state);
103	}
104	if (status < 0)
105		printk(err_suspend, status);
106
107	/* Some platforms can't detect that the alarm triggered the
108	 * wakeup, or (accordingly) disable it after it afterwards.
109	 * It's supposed to give oneshot behavior; cope.
110	 */
111	alm.enabled = false;
112	rtc_set_alarm(rtc, &alm);
113}
114
115static int __init has_wakealarm(struct device *dev, void *name_ptr)
116{
117	struct rtc_device *candidate = to_rtc_device(dev);
118
119	if (!candidate->ops->set_alarm)
120		return 0;
121	if (!device_may_wakeup(candidate->dev.parent))
122		return 0;
123
124	*(const char **)name_ptr = dev_name(dev);
125	return 1;
126}
127
128/*
129 * Kernel options like "test_suspend=mem" force suspend/resume sanity tests
130 * at startup time.  They're normally disabled, for faster boot and because
131 * we can't know which states really work on this particular system.
132 */
133static suspend_state_t test_state __initdata = PM_SUSPEND_ON;
134
135static char warn_bad_state[] __initdata =
136	KERN_WARNING "PM: can't test '%s' suspend state\n";
137
138static int __init setup_test_suspend(char *value)
139{
140	unsigned i;
141
142	/* "=mem" ==> "mem" */
143	value++;
144	for (i = 0; i < PM_SUSPEND_MAX; i++) {
145		if (!pm_states[i])
146			continue;
147		if (strcmp(pm_states[i], value) != 0)
148			continue;
149		test_state = (__force suspend_state_t) i;
150		return 0;
151	}
152	printk(warn_bad_state, value);
153	return 0;
154}
155__setup("test_suspend", setup_test_suspend);
156
157static int __init test_suspend(void)
158{
159	static char		warn_no_rtc[] __initdata =
160		KERN_WARNING "PM: no wakealarm-capable RTC driver is ready\n";
161
162	char			*pony = NULL;
163	struct rtc_device	*rtc = NULL;
164
165	/* PM is initialized by now; is that state testable? */
166	if (test_state == PM_SUSPEND_ON)
167		goto done;
168	if (!valid_state(test_state)) {
169		printk(warn_bad_state, pm_states[test_state]);
170		goto done;
171	}
172
173	/* RTCs have initialized by now too ... can we use one? */
174	class_find_device(rtc_class, NULL, &pony, has_wakealarm);
175	if (pony)
176		rtc = rtc_class_open(pony);
177	if (!rtc) {
178		printk(warn_no_rtc);
179		goto done;
180	}
181
182	/* go for it */
183	test_wakealarm(rtc, test_state);
184	rtc_class_close(rtc);
185done:
186	return 0;
187}
188late_initcall(test_suspend);