xref: /openbmc/linux/kernel/power/suspend_test.c (revision 7e45fc93)
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 
23 static unsigned long suspend_test_start_time;
24 static u32 test_repeat_count_max = 1;
25 static u32 test_repeat_count_current;
26 
suspend_test_start(void)27 void 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 
suspend_test_finish(const char * label)36 void 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 
test_wakealarm(struct rtc_device * rtc,suspend_state_t state)62 static 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 */
78 repeat:
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 
has_wakealarm(struct device * dev,const void * data)128 static int __init has_wakealarm(struct device *dev, const void *data)
129 {
130 	struct rtc_device *candidate = to_rtc_device(dev);
131 
132 	if (!test_bit(RTC_FEATURE_ALARM, candidate->features))
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  */
145 static const char *test_state_label __initdata;
146 
147 static char warn_bad_state[] __initdata =
148 	KERN_WARNING "PM: can't test '%s' suspend state\n";
149 
setup_test_suspend(char * value)150 static 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 1;
161 
162 	repeat = strsep(&value, ",");
163 	if (repeat) {
164 		if (kstrtou32(repeat, 0, &test_repeat_count_max))
165 			return 1;
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 1;
172 		}
173 
174 	printk(warn_bad_state, suspend_type);
175 	return 1;
176 }
177 __setup("test_suspend", setup_test_suspend);
178 
test_suspend(void)179 static 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 }
219 late_initcall(test_suspend);
220