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 5
23
24 static unsigned long suspend_test_start_time;
25
26 void 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
35 void 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), "Component: %s\n", label);
53 }
54
55 /*
56 * To test system suspend, we need a hands-off mechanism to resume the
57 * system. RTCs wake alarms are a common self-contained mechanism.
58 */
59
60 static void __init test_wakealarm(struct rtc_device *rtc, suspend_state_t state)
61 {
62 static char err_readtime[] __initdata =
63 KERN_ERR "PM: can't read %s time, err %d\n";
64 static char err_wakealarm [] __initdata =
65 KERN_ERR "PM: can't set %s wakealarm, err %d\n";
66 static char err_suspend[] __initdata =
67 KERN_ERR "PM: suspend test failed, error %d\n";
68 static char info_test[] __initdata =
69 KERN_INFO "PM: test RTC wakeup from '%s' suspend\n";
70
71 unsigned long now;
72 struct rtc_wkalrm alm;
73 int status;
74
75 /* this may fail if the RTC hasn't been initialized */
76 status = rtc_read_time(rtc, &alm.time);
77 if (status < 0) {
78 printk(err_readtime, dev_name(&rtc->dev), status);
79 return;
80 }
81 rtc_tm_to_time(&alm.time, &now);
82
83 memset(&alm, 0, sizeof alm);
84 rtc_time_to_tm(now + TEST_SUSPEND_SECONDS, &alm.time);
85 alm.enabled = true;
86
87 status = rtc_set_alarm(rtc, &alm);
88 if (status < 0) {
89 printk(err_wakealarm, dev_name(&rtc->dev), status);
90 return;
91 }
92
93 if (state == PM_SUSPEND_MEM) {
94 printk(info_test, pm_states[state]);
95 status = pm_suspend(state);
96 if (status == -ENODEV)
97 state = PM_SUSPEND_STANDBY;
98 }
99 if (state == PM_SUSPEND_STANDBY) {
100 printk(info_test, pm_states[state]);
101 status = pm_suspend(state);
102 }
103 if (status < 0)
104 printk(err_suspend, status);
105
106 /* Some platforms can't detect that the alarm triggered the
107 * wakeup, or (accordingly) disable it after it afterwards.
108 * It's supposed to give oneshot behavior; cope.
109 */
110 alm.enabled = false;
111 rtc_set_alarm(rtc, &alm);
112 }
113
114 static int __init has_wakealarm(struct device *dev, void *name_ptr)
115 {
116 struct rtc_device *candidate = to_rtc_device(dev);
117
118 if (!candidate->ops->set_alarm)
119 return 0;
120 if (!device_may_wakeup(candidate->dev.parent))
121 return 0;
122
123 *(const char **)name_ptr = dev_name(dev);
124 return 1;
125 }
126
127 /*
128 * Kernel options like "test_suspend=mem" force suspend/resume sanity tests
129 * at startup time. They're normally disabled, for faster boot and because
130 * we can't know which states really work on this particular system.
131 */
132 static suspend_state_t test_state __initdata = PM_SUSPEND_ON;
133
134 static char warn_bad_state[] __initdata =
135 KERN_WARNING "PM: can't test '%s' suspend state\n";
136
137 static int __init setup_test_suspend(char *value)
138 {
139 unsigned i;
140
141 /* "=mem" ==> "mem" */
142 value++;
143 for (i = 0; i < PM_SUSPEND_MAX; i++) {
144 if (!pm_states[i])
145 continue;
146 if (strcmp(pm_states[i], value) != 0)
147 continue;
148 test_state = (__force suspend_state_t) i;
149 return 0;
150 }
151 printk(warn_bad_state, value);
152 return 0;
153 }
154 __setup("test_suspend", setup_test_suspend);
155
156 static int __init test_suspend(void)
157 {
158 static char warn_no_rtc[] __initdata =
159 KERN_WARNING "PM: no wakealarm-capable RTC driver is ready\n";
160
161 char *pony = NULL;
162 struct rtc_device *rtc = NULL;
163
164 /* PM is initialized by now; is that state testable? */
165 if (test_state == PM_SUSPEND_ON)
166 goto done;
167 if (!valid_state(test_state)) {
168 printk(warn_bad_state, pm_states[test_state]);
169 goto done;
170 }
171
172 /* RTCs have initialized by now too ... can we use one? */
173 class_find_device(rtc_class, NULL, &pony, has_wakealarm);
174 if (pony)
175 rtc = rtc_class_open(pony);
176 if (!rtc) {
177 printk(warn_no_rtc);
178 goto done;
179 }
180
181 /* go for it */
182 test_wakealarm(rtc, test_state);
183 rtc_class_close(rtc);
184 done:
185 return 0;
186 }
187 late_initcall(test_suspend);
188
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