rtcwakeup.c
- From: David Brownell <david-b@xxxxxxxxxxx>
- Date: Sat, 15 Jul 2006 12:48:07 -0700
p.s. A followup message will include a userspace program which
makes it easier to try the RTC wakeup mechanism.
For example, if your system actually supports RTC wakeup correctly:
rtcwake -t $(date -u -d 'tomorrow 6:30am' +'%s') -m mem
will set up the system to wake up tomorrow at 6:30am, then suspend-to-RAM by
writing "mem" to /sys/power/state.
Or for testing kernels, unattended scripts like this may help:
while true
do
echo "suspend-to-disk for 10 minutes starting $(date)"
rtcwake -s $((10 * 60)) -m disk
sleep 500
done
If there are many RTC utilities out there that aren't x86-specific, I didn't
happen to find them. Ergo this one.
- Dave
#include <stdio.h>
#include <getopt.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <time.h>
#include <sys/ioctl.h>
#include <sys/time.h>
#include <sys/types.h>
#include <linux/rtc.h>
// #define DEBUG
/*
* rtcwake -- enter a system sleep state until specified wakeup time.
*
* 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.
*/
static char *progname;
#ifdef DEBUG
#define VERSION "1.0 dev (" __DATE__ " " __TIME__ ")"
#else
#define VERSION "0.8"
#endif
static unsigned verbose;
static int may_wakeup(const char *devname)
{
char buf[128], *s;
FILE *f;
snprintf(buf, sizeof buf, "/sys/class/rtc/%s/device/power/wakeup",
devname);
f = fopen(buf, "r");
if (!f) {
perror(buf);
return 0;
}
fgets(buf, sizeof buf, f);
fclose(f);
s = strchr(buf, '\n');
if (!s)
return 0;
*s = 0;
/* wakeup events could be disabled or not supported */
return strcmp(buf, "enabled") == 0;
}
/* all times should be in UTC */
static time_t sys_time;
static time_t rtc_time;
static int get_basetimes(int fd)
{
struct tm tm;
time_t offset;
struct rtc_time rtc;
/* record offset of mktime(), so we can reverse it */
memset(&tm, 0, sizeof tm);
tm.tm_year = 70;
offset = mktime(&tm);
/* read system and rtc clocks "at the same time"; both in UTC */
sys_time = time(0);
if (sys_time == (time_t)-1) {
perror("read system time");
return 0;
}
if (ioctl(fd, RTC_RD_TIME, &rtc) < 0) {
perror("read rtc time");
return 0;
}
/* convert rtc_time to normal arithmetic-friendly form */
tm.tm_sec = rtc.tm_sec;
tm.tm_min = rtc.tm_min;
tm.tm_hour = rtc.tm_hour;
tm.tm_mday = rtc.tm_mday;
tm.tm_mon = rtc.tm_mon;
tm.tm_year = rtc.tm_year;
tm.tm_wday = rtc.tm_wday;
tm.tm_yday = rtc.tm_yday;
tm.tm_isdst = rtc.tm_isdst;
if (verbose) {
printf("\toffset = %ld\n", offset);
printf("\tsystime = %s", asctime(gmtime(&sys_time)));
printf("\trtctime = %s", asctime(&tm));
}
rtc_time = mktime(&tm) - offset;
if (rtc_time == (time_t)-1) {
perror("convert rtc time");
return 0;
}
return 1;
}
static int setup_alarm(int fd, time_t *wakeup)
{
struct tm *tm;
struct rtc_wkalrm wake;
tm = gmtime(wakeup);
wake.time.tm_sec = tm->tm_sec;
wake.time.tm_min = tm->tm_min;
wake.time.tm_hour = tm->tm_hour;
wake.time.tm_mday = tm->tm_mday;
wake.time.tm_mon = tm->tm_mon;
wake.time.tm_year = tm->tm_year;
wake.time.tm_wday = tm->tm_wday;
wake.time.tm_yday = tm->tm_yday;
wake.time.tm_isdst = tm->tm_isdst;
/* many rtc alarms only support up to 24 hours from 'now' ... */
if ((rtc_time + 24 * 60 * 60) > *wakeup) {
if (ioctl(fd, RTC_ALM_SET, &wake.time) < 0) {
perror("set rtc alarm");
return 0;
}
if (ioctl(fd, RTC_AIE_ON, 0) < 0) {
perror("enable rtc alarm");
return 0;
}
/* ... so use the "more than 24 hours" request only if we must */
} else {
/* avoid an extra AIE_ON call */
wake.enabled = 1;
if (ioctl(fd, RTC_WKALM_SET, &wake) < 0) {
perror("set rtc wake alarm");
return 0;
}
}
return 1;
}
static void suspend_system(const char *suspend)
{
FILE *f = fopen("/sys/power/state", "w");
if (!f) {
perror("/sys/power/state");
return;
}
fprintf(f, "%s\n", suspend);
fflush(f);
/* this executes after wake from suspend */
fclose(f);
}
int main(int argc, char **argv)
{
static char *devname = "rtc0";
static unsigned seconds = 0;
static char *suspend = "standby";
int t;
int fd;
time_t alarm = 0;
progname = strrchr(argv[0], '/');
if (progname)
progname++;
else
progname = argv[0];
if (chdir("/dev/") < 0) {
perror("chdir /dev");
return 1;
}
while ((t = getopt(argc, argv, "d:m:s:t:Vv")) != EOF) {
switch (t) {
case 'd':
devname = optarg;
break;
/* what system power mode to use? for now handle only
* standardized mode names; eventually when systems define
* their own state names, parse /sys/power/state.
*
* "on" is used just to test the RTC alarm mechanism,
* bypassing all the wakeup-from-sleep infrastructure.
*/
case 'm':
if (strcmp(optarg, "standby") == 0
|| strcmp(optarg, "mem") == 0
|| strcmp(optarg, "disk") == 0
|| strcmp(optarg, "on") == 0
) {
suspend = optarg;
break;
}
printf("%s: unrecognized suspend state '%s'\n",
progname, optarg);
goto usage;
/* alarm time, seconds-to-sleep (relative) */
case 's':
t = atoi(optarg);
if (t < 0) {
printf("%s: illegal interval %s seconds\n",
progname, optarg);
goto usage;
}
seconds = t;
break;
/* alarm time, time_t (absolute, seconds since 1/1 1970 UTC) */
case 't':
t = atoi(optarg);
if (t < 0) {
printf("%s: illegal time_t value %s\n",
progname, optarg);
goto usage;
}
alarm = t;
break;
case 'v':
verbose++;
break;
case 'V':
printf("%s: version %s\n", progname, VERSION);
break;
default:
usage:
printf("usage: %s [options]"
"\n\t"
"-d rtc0|rtc1|...\t(select rtc)"
"\n\t"
"-m standby|mem|...\t(sleep mode)"
"\n\t"
"-s seconds\t\t(seconds to sleep)"
"\n\t"
"-t time_t\t\t(time to wake)"
"\n\t"
"-v\t\t\t(verbose messages)"
"\n\t"
"-V\t\t\t(show version)"
"\n",
progname);
return 1;
}
}
if (!alarm && !seconds) {
printf("%s: must provide wake time\n", progname);
goto usage;
}
/* this RTC must exist and (if we'll sleep) be wakeup-enabled */
fd = open(devname, O_RDONLY);
if (fd < 0) {
perror(devname);
return 1;
}
if (strcmp(suspend, "on") != 0 && !may_wakeup(devname)) {
printf("%s: %s not enabled for wakeup events\n",
progname, devname);
return 1;
}
/* relative or absolute alarm time, normalized to time_t */
if (!get_basetimes(fd))
return 1;
if (verbose)
printf("alarm %ld, sys_time %ld, rtc_time %ld, seconds %u\n",
alarm, sys_time, rtc_time, seconds);
if (alarm) {
if (alarm < sys_time) {
printf("%s: time doesn't go backward to %s",
progname, ctime(&alarm));
return 1;
}
alarm += sys_time - rtc_time;
} else
alarm = rtc_time + seconds + 1;
if (setup_alarm(fd, &alarm) < 0)
return 1;
printf("%s: wakeup from \"%s\" using %s at %s",
progname, suspend, devname,
ctime(&alarm));
fflush(stdout);
usleep(10 * 1000);
if (strcmp(suspend, "on") != 0)
suspend_system(suspend);
else {
unsigned long data;
(void) read(fd, &data, sizeof data);
}
if (ioctl(fd, RTC_AIE_OFF, 0) < 0)
perror("disable rtc alarm interrupt");
close(fd);
return 0;
}
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- References:
- [patch 2.6.18-rc1-git] rtc-acpi, with wakeup support
- From: David Brownell
- [patch 2.6.18-rc1-git] rtc-acpi, with wakeup support
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