blob: 8aee0cfcbd567dc8c0682da07e587387ee685f09 [file] [log] [blame]
* rtcwake -- enter a system sleep state until specified wakeup time.
* This version was taken from util-linux and scrubbed down for busybox.
* Licensed under GPLv2, see file LICENSE in this source tree.
* This uses cross-platform Linux interfaces to enter a system sleep state,
* and leave it no later than a specified time. It uses any RTC framework
* driver that supports standard driver model wakeup flags.
* This is normally used like the old "apmsleep" utility, to wake from a
* suspend state like ACPI S1 (standby) or S3 (suspend-to-RAM). Most
* platforms can implement those without analogues of BIOS, APM, or ACPI.
* On some systems, this can also be used like "nvram-wakeup", waking
* from states like ACPI S4 (suspend to disk). Not all systems have
* persistent media that are appropriate for such suspend modes.
* The best way to set the system's RTC is so that it holds the current
* time in UTC. Use the "-l" flag to tell this program that the system
* RTC uses a local timezone instead (maybe you dual-boot MS-Windows).
* That flag should not be needed on systems with adjtime support.
//usage:#define rtcwake_trivial_usage
//usage: "[-a | -l | -u] [-d DEV] [-m MODE] [-s SEC | -t TIME]"
//usage:#define rtcwake_full_usage "\n\n"
//usage: "Enter a system sleep state until specified wakeup time\n"
//usage: IF_LONG_OPTS(
//usage: "\n -a,--auto Read clock mode from adjtime"
//usage: "\n -l,--local Clock is set to local time"
//usage: "\n -u,--utc Clock is set to UTC time"
//usage: "\n -d,--device=DEV Specify the RTC device"
//usage: "\n -m,--mode=MODE Set sleep state (default: standby)"
//usage: "\n -s,--seconds=SEC Set timeout in SEC seconds from now"
//usage: "\n -t,--time=TIME Set timeout to TIME seconds from epoch"
//usage: )
//usage: IF_NOT_LONG_OPTS(
//usage: "\n -a Read clock mode from adjtime"
//usage: "\n -l Clock is set to local time"
//usage: "\n -u Clock is set to UTC time"
//usage: "\n -d DEV Specify the RTC device"
//usage: "\n -m MODE Set sleep state (default: standby)"
//usage: "\n -s SEC Set timeout in SEC seconds from now"
//usage: "\n -t TIME Set timeout to TIME seconds from epoch"
//usage: )
#include "libbb.h"
#include "rtc_.h"
#define SYS_RTC_PATH "/sys/class/rtc/%s/device/power/wakeup"
#define SYS_POWER_PATH "/sys/power/state"
static NOINLINE bool may_wakeup(const char *rtcname)
ssize_t ret;
char buf[128];
/* strip "/dev/" from the rtcname here */
rtcname = skip_dev_pfx(rtcname);
snprintf(buf, sizeof(buf), SYS_RTC_PATH, rtcname);
ret = open_read_close(buf, buf, sizeof(buf));
if (ret < 0)
return false;
/* wakeup events could be disabled or not supported */
return is_prefixed_with(buf, "enabled\n") != NULL;
static NOINLINE void setup_alarm(int fd, time_t *wakeup, time_t rtc_time)
struct tm *ptm;
struct linux_rtc_wkalrm wake;
/* The wakeup time is in POSIX time (more or less UTC).
* Ideally RTCs use that same time; but PCs can't do that
* if they need to boot MS-Windows. Messy...
* When running in utc mode this process's timezone is UTC,
* so we'll pass a UTC date to the RTC.
* Else mode is local so the time given to the RTC
* will instead use the local time zone.
ptm = localtime(wakeup);
wake.time.tm_sec = ptm->tm_sec;
wake.time.tm_min = ptm->tm_min;
wake.time.tm_hour = ptm->tm_hour;
wake.time.tm_mday = ptm->tm_mday;
wake.time.tm_mon = ptm->tm_mon;
wake.time.tm_year = ptm->tm_year;
/* wday, yday, and isdst fields are unused by Linux */
wake.time.tm_wday = -1;
wake.time.tm_yday = -1;
wake.time.tm_isdst = -1;
/* many rtc alarms only support up to 24 hours from 'now',
* so use the "more than 24 hours" request only if we must
if ((rtc_time + (24 * 60 * 60)) > *wakeup) {
xioctl(fd, RTC_ALM_SET, &wake.time);
xioctl(fd, RTC_AIE_ON, 0);
} else {
/* avoid an extra AIE_ON call */
wake.enabled = 1;
xioctl(fd, RTC_WKALM_SET, &wake);
#define RTCWAKE_OPT_AUTO 0x01
#define RTCWAKE_OPT_LOCAL 0x02
#define RTCWAKE_OPT_UTC 0x04
#define RTCWAKE_OPT_TIME 0x40
int rtcwake_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int rtcwake_main(int argc UNUSED_PARAM, char **argv)
unsigned opt;
const char *rtcname = NULL;
const char *suspend = "standby";
const char *opt_seconds;
const char *opt_time;
time_t rtc_time;
time_t sys_time;
time_t alarm_time = alarm_time;
unsigned seconds = seconds; /* for compiler */
int utc = -1;
int fd;
static const char rtcwake_longopts[] ALIGN1 =
"auto\0" No_argument "a"
"local\0" No_argument "l"
"utc\0" No_argument "u"
"device\0" Required_argument "d"
"mode\0" Required_argument "m"
"seconds\0" Required_argument "s"
"time\0" Required_argument "t"
applet_long_options = rtcwake_longopts;
/* Must have -s or -t, exclusive */
opt_complementary = "s:t:s--t:t--s";
opt = getopt32(argv, "alud:m:s:t:", &rtcname, &suspend, &opt_seconds, &opt_time);
/* this is the default
utc = -1;
utc = opt & RTCWAKE_OPT_UTC;
/* alarm time, seconds-to-sleep (relative) */
seconds = xatou(opt_seconds);
} else {
/* alarm time, time_t (absolute, seconds since 1/1 1970 UTC) */
if (sizeof(alarm_time) <= sizeof(long))
alarm_time = xatol(opt_time);
alarm_time = xatoll(opt_time);
if (utc == -1)
utc = rtc_adjtime_is_utc();
/* the rtcname is relative to /dev */
/* this RTC must exist and (if we'll sleep) be wakeup-enabled */
fd = rtc_xopen(&rtcname, O_RDONLY);
if (strcmp(suspend, "on") != 0)
if (!may_wakeup(rtcname))
bb_error_msg_and_die("%s not enabled for wakeup events", rtcname);
/* relative or absolute alarm time, normalized to time_t */
sys_time = time(NULL);
struct tm tm_time;
rtc_read_tm(&tm_time, fd);
rtc_time = rtc_tm2time(&tm_time, utc);
if (opt & RTCWAKE_OPT_TIME) {
/* Correct for RTC<->system clock difference */
alarm_time += rtc_time - sys_time;
if (alarm_time < rtc_time)
* Compat message text.
* I'd say "RTC time is already ahead of ..." instead.
bb_error_msg_and_die("time doesn't go backward to %s", ctime(&alarm_time));
} else
alarm_time = rtc_time + seconds + 1;
setup_alarm(fd, &alarm_time, rtc_time);
#if 0 /*debug*/
printf("sys_time: %s", ctime(&sys_time));
printf("rtc_time: %s", ctime(&rtc_time));
printf("wakeup from \"%s\" at %s", suspend, ctime(&alarm_time));
usleep(10 * 1000);
if (strcmp(suspend, "on") != 0)
xopen_xwrite_close(SYS_POWER_PATH, suspend);
else {
/* "fake" suspend ... we'll do the delay ourselves */
unsigned long data;
do {
ssize_t ret = safe_read(fd, &data, sizeof(data));
if (ret < 0) {
bb_perror_msg("rtc read");
} while (!(data & RTC_AF));
xioctl(fd, RTC_AIE_OFF, 0);