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 * This uses cross-platform Linux interfaces to enter a system sleep state,
7 * and leave it no later than a specified time. It uses any RTC framework
8 * driver that supports standard driver model wakeup flags.
10 * This is normally used like the old "apmsleep" utility, to wake from a
11 * suspend state like ACPI S1 (standby) or S3 (suspend-to-RAM). Most
12 * platforms can implement those without analogues of BIOS, APM, or ACPI.
14 * On some systems, this can also be used like "nvram-wakeup", waking
15 * from states like ACPI S4 (suspend to disk). Not all systems have
16 * persistent media that are appropriate for such suspend modes.
18 * The best way to set the system's RTC is so that it holds the current
19 * time in UTC. Use the "-l" flag to tell this program that the system
20 * RTC uses a local timezone instead (maybe you dual-boot MS-Windows).
21 * That flag should not be needed on systems with adjtime support.
27 #define SYS_RTC_PATH "/sys/class/rtc/%s/device/power/wakeup"
28 #define SYS_POWER_PATH "/sys/power/state"
29 #define DEFAULT_MODE "suspend"
31 static time_t rtc_time;
33 static int may_wakeup(const char *rtcname)
38 /* strip the '/dev/' from the rtcname here */
39 if (!strncmp(rtcname, "/dev/", 5))
42 snprintf(buf, sizeof(buf), SYS_RTC_PATH, rtcname);
43 ret = open_read_close(buf, buf, sizeof(buf));
47 /* wakeup events could be disabled or not supported */
48 return strncmp(buf, "enabled\n", 8) == 0;
51 static void setup_alarm(int fd, time_t *wakeup)
54 struct linux_rtc_wkalrm wake;
56 /* The wakeup time is in POSIX time (more or less UTC).
57 * Ideally RTCs use that same time; but PCs can't do that
58 * if they need to boot MS-Windows. Messy...
60 * When running in utc mode this process's timezone is UTC,
61 * so we'll pass a UTC date to the RTC.
63 * Else mode is local so the time given to the RTC
64 * will instead use the local time zone.
66 tm = localtime(wakeup);
68 wake.time.tm_sec = tm->tm_sec;
69 wake.time.tm_min = tm->tm_min;
70 wake.time.tm_hour = tm->tm_hour;
71 wake.time.tm_mday = tm->tm_mday;
72 wake.time.tm_mon = tm->tm_mon;
73 wake.time.tm_year = tm->tm_year;
74 /* wday, yday, and isdst fields are unused by Linux */
75 wake.time.tm_wday = -1;
76 wake.time.tm_yday = -1;
77 wake.time.tm_isdst = -1;
79 /* many rtc alarms only support up to 24 hours from 'now',
80 * so use the "more than 24 hours" request only if we must
82 if ((rtc_time + (24 * 60 * 60)) > *wakeup) {
83 xioctl(fd, RTC_ALM_SET, &wake.time);
84 xioctl(fd, RTC_AIE_ON, 0);
86 /* avoid an extra AIE_ON call */
88 xioctl(fd, RTC_WKALM_SET, &wake);
92 static void suspend_system(const char *suspend)
94 FILE *f = xfopen(SYS_POWER_PATH, "w");
95 fprintf(f, "%s\n", suspend);
97 /* this executes after wake from suspend */
101 #define RTCWAKE_OPT_AUTO 0x01
102 #define RTCWAKE_OPT_LOCAL 0x02
103 #define RTCWAKE_OPT_UTC 0x04
104 #define RTCWAKE_OPT_DEVICE 0x08
105 #define RTCWAKE_OPT_SUSPEND_MODE 0x10
106 #define RTCWAKE_OPT_SECONDS 0x20
107 #define RTCWAKE_OPT_TIME 0x40
109 int rtcwake_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
110 int rtcwake_main(int argc ATTRIBUTE_UNUSED, char **argv)
113 const char *rtcname = NULL;
115 const char *opt_seconds;
116 const char *opt_time;
119 time_t alarm_time = 0;
120 unsigned seconds = 0;
124 #if ENABLE_GETOPT_LONG
125 static const char rtcwake_longopts[] ALIGN1 =
126 "auto\0" No_argument "a"
127 "local\0" No_argument "l"
128 "utc\0" No_argument "u"
129 "device\0" Required_argument "d"
130 "mode\0" Required_argument "m"
131 "seconds\0" Required_argument "s"
132 "time\0" Required_argument "t"
134 applet_long_options = rtcwake_longopts;
136 opt = getopt32(argv, "alud:m:s:t:", &rtcname, &suspend, &opt_seconds, &opt_time);
138 /* this is the default
139 if (opt & RTCWAKE_OPT_AUTO)
142 if (opt & (RTCWAKE_OPT_UTC | RTCWAKE_OPT_LOCAL))
143 utc = opt & RTCWAKE_OPT_UTC;
144 if (!(opt & RTCWAKE_OPT_SUSPEND_MODE))
145 suspend = DEFAULT_MODE;
146 if (opt & RTCWAKE_OPT_SECONDS)
147 /* alarm time, seconds-to-sleep (relative) */
148 seconds = xatoi(opt_seconds);
149 if (opt & RTCWAKE_OPT_TIME)
150 /* alarm time, time_t (absolute, seconds since 1/1 1970 UTC) */
151 alarm_time = xatoi(opt_time);
153 if (!alarm_time && !seconds)
154 bb_error_msg_and_die("must provide wake time");
157 utc = rtc_adjtime_is_utc();
159 /* the rtcname is relative to /dev */
162 /* this RTC must exist and (if we'll sleep) be wakeup-enabled */
163 fd = rtc_xopen(&rtcname, O_RDONLY);
165 if (strcmp(suspend, "on") && !may_wakeup(rtcname))
166 bb_error_msg_and_die("%s not enabled for wakeup events", rtcname);
168 /* relative or absolute alarm time, normalized to time_t */
170 if (sys_time == (time_t)-1)
171 bb_perror_msg_and_die("read system time");
172 rtc_time = rtc_read_time(fd, utc);
175 if (alarm_time < sys_time)
176 bb_error_msg_and_die("time doesn't go backward to %s", ctime(&alarm_time));
177 alarm_time += sys_time - rtc_time;
179 alarm_time = rtc_time + seconds + 1;
180 setup_alarm(fd, &alarm_time);
183 printf("wakeup from \"%s\" at %s", suspend, ctime(&alarm_time));
187 if (strcmp(suspend, "on"))
188 suspend_system(suspend);
190 /* "fake" suspend ... we'll do the delay ourselves */
194 ssize_t ret = safe_read(fd, &data, sizeof(data));
196 bb_perror_msg("rtc read");
199 } while (!(data & RTC_AF));
202 xioctl(fd, RTC_AIE_OFF, 0);
204 if (ENABLE_FEATURE_CLEAN_UP)