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