2 * rtcwake -- enter a system sleep state until specified wakeup time.
4 * This version was taken from util-linux and scrubbed down for busybox.
6 * Licensed under GPLv2, see file LICENSE in this tarball for details.
8 * This uses cross-platform Linux interfaces to enter a system sleep state,
9 * and leave it no later than a specified time. It uses any RTC framework
10 * driver that supports standard driver model wakeup flags.
12 * This is normally used like the old "apmsleep" utility, to wake from a
13 * suspend state like ACPI S1 (standby) or S3 (suspend-to-RAM). Most
14 * platforms can implement those without analogues of BIOS, APM, or ACPI.
16 * On some systems, this can also be used like "nvram-wakeup", waking
17 * from states like ACPI S4 (suspend to disk). Not all systems have
18 * persistent media that are appropriate for such suspend modes.
20 * The best way to set the system's RTC is so that it holds the current
21 * time in UTC. Use the "-l" flag to tell this program that the system
22 * RTC uses a local timezone instead (maybe you dual-boot MS-Windows).
23 * That flag should not be needed on systems with adjtime support.
29 #define SYS_RTC_PATH "/sys/class/rtc/%s/device/power/wakeup"
30 #define SYS_POWER_PATH "/sys/power/state"
31 #define DEFAULT_MODE "standby"
33 static time_t rtc_time;
35 static bool may_wakeup(const char *rtcname)
40 /* strip the '/dev/' from the rtcname here */
41 if (!strncmp(rtcname, "/dev/", 5))
44 snprintf(buf, sizeof(buf), SYS_RTC_PATH, rtcname);
45 ret = open_read_close(buf, buf, sizeof(buf));
49 /* wakeup events could be disabled or not supported */
50 return strncmp(buf, "enabled\n", 8) == 0;
53 static void setup_alarm(int fd, time_t *wakeup)
56 struct linux_rtc_wkalrm wake;
58 /* The wakeup time is in POSIX time (more or less UTC).
59 * Ideally RTCs use that same time; but PCs can't do that
60 * if they need to boot MS-Windows. Messy...
62 * When running in utc mode this process's timezone is UTC,
63 * so we'll pass a UTC date to the RTC.
65 * Else mode is local so the time given to the RTC
66 * will instead use the local time zone.
68 tm = localtime(wakeup);
70 wake.time.tm_sec = tm->tm_sec;
71 wake.time.tm_min = tm->tm_min;
72 wake.time.tm_hour = tm->tm_hour;
73 wake.time.tm_mday = tm->tm_mday;
74 wake.time.tm_mon = tm->tm_mon;
75 wake.time.tm_year = tm->tm_year;
76 /* wday, yday, and isdst fields are unused by Linux */
77 wake.time.tm_wday = -1;
78 wake.time.tm_yday = -1;
79 wake.time.tm_isdst = -1;
81 /* many rtc alarms only support up to 24 hours from 'now',
82 * so use the "more than 24 hours" request only if we must
84 if ((rtc_time + (24 * 60 * 60)) > *wakeup) {
85 xioctl(fd, RTC_ALM_SET, &wake.time);
86 xioctl(fd, RTC_AIE_ON, 0);
88 /* avoid an extra AIE_ON call */
90 xioctl(fd, RTC_WKALM_SET, &wake);
94 #define RTCWAKE_OPT_AUTO 0x01
95 #define RTCWAKE_OPT_LOCAL 0x02
96 #define RTCWAKE_OPT_UTC 0x04
97 #define RTCWAKE_OPT_DEVICE 0x08
98 #define RTCWAKE_OPT_SUSPEND_MODE 0x10
99 #define RTCWAKE_OPT_SECONDS 0x20
100 #define RTCWAKE_OPT_TIME 0x40
102 int rtcwake_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
103 int rtcwake_main(int argc UNUSED_PARAM, char **argv)
106 const char *rtcname = NULL;
108 const char *opt_seconds;
109 const char *opt_time;
112 time_t alarm_time = 0;
113 unsigned seconds = 0;
118 static const char rtcwake_longopts[] ALIGN1 =
119 "auto\0" No_argument "a"
120 "local\0" No_argument "l"
121 "utc\0" No_argument "u"
122 "device\0" Required_argument "d"
123 "mode\0" Required_argument "m"
124 "seconds\0" Required_argument "s"
125 "time\0" Required_argument "t"
127 applet_long_options = rtcwake_longopts;
129 opt = getopt32(argv, "alud:m:s:t:", &rtcname, &suspend, &opt_seconds, &opt_time);
131 /* this is the default
132 if (opt & RTCWAKE_OPT_AUTO)
135 if (opt & (RTCWAKE_OPT_UTC | RTCWAKE_OPT_LOCAL))
136 utc = opt & RTCWAKE_OPT_UTC;
137 if (!(opt & RTCWAKE_OPT_SUSPEND_MODE))
138 suspend = DEFAULT_MODE;
139 if (opt & RTCWAKE_OPT_SECONDS)
140 /* alarm time, seconds-to-sleep (relative) */
141 seconds = xatoi(opt_seconds);
142 if (opt & RTCWAKE_OPT_TIME)
143 /* alarm time, time_t (absolute, seconds since 1/1 1970 UTC) */
144 alarm_time = xatoi(opt_time);
146 if (!alarm_time && !seconds)
147 bb_error_msg_and_die("must provide wake time");
150 utc = rtc_adjtime_is_utc();
152 /* the rtcname is relative to /dev */
155 /* this RTC must exist and (if we'll sleep) be wakeup-enabled */
156 fd = rtc_xopen(&rtcname, O_RDONLY);
158 if (strcmp(suspend, "on") && !may_wakeup(rtcname))
159 bb_error_msg_and_die("%s not enabled for wakeup events", rtcname);
161 /* relative or absolute alarm time, normalized to time_t */
162 sys_time = time(NULL);
163 if (sys_time == (time_t)-1)
164 bb_perror_msg_and_die("read system time");
165 rtc_time = rtc_read_time(fd, utc);
168 if (alarm_time < sys_time)
169 bb_error_msg_and_die("time doesn't go backward to %s", ctime(&alarm_time));
170 alarm_time += sys_time - rtc_time;
172 alarm_time = rtc_time + seconds + 1;
173 setup_alarm(fd, &alarm_time);
176 printf("wakeup from \"%s\" at %s", suspend, ctime(&alarm_time));
180 if (strcmp(suspend, "on"))
181 xopen_xwrite_close(SYS_POWER_PATH, suspend);
183 /* "fake" suspend ... we'll do the delay ourselves */
187 ssize_t ret = safe_read(fd, &data, sizeof(data));
189 bb_perror_msg("rtc read");
192 } while (!(data & RTC_AF));
195 xioctl(fd, RTC_AIE_OFF, 0);
197 if (ENABLE_FEATURE_CLEAN_UP)