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rtcwake.c 5.7 KB

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  1. /*
  2. * rtcwake -- enter a system sleep state until specified wakeup time.
  3. *
  4. * This version was taken from util-linux and scrubbed down for busybox.
  5. *
  6. * Licensed under GPLv2, see file LICENSE in this tarball for details.
  7. *
  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.
  11. *
  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.
  15. *
  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.
  19. *
  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.
  24. */
  25. #include "libbb.h"
  26. #include "rtc_.h"
  27. #define SYS_RTC_PATH "/sys/class/rtc/%s/device/power/wakeup"
  28. #define SYS_POWER_PATH "/sys/power/state"
  29. #define DEFAULT_MODE "standby"
  30. static NOINLINE bool may_wakeup(const char *rtcname)
  31. {
  32. ssize_t ret;
  33. char buf[128];
  34. /* strip "/dev/" from the rtcname here */
  35. rtcname = skip_dev_pfx(rtcname);
  36. snprintf(buf, sizeof(buf), SYS_RTC_PATH, rtcname);
  37. ret = open_read_close(buf, buf, sizeof(buf));
  38. if (ret < 0)
  39. return false;
  40. /* wakeup events could be disabled or not supported */
  41. return strncmp(buf, "enabled\n", 8) == 0;
  42. }
  43. static NOINLINE void setup_alarm(int fd, time_t *wakeup, time_t rtc_time)
  44. {
  45. struct tm *ptm;
  46. struct linux_rtc_wkalrm wake;
  47. /* The wakeup time is in POSIX time (more or less UTC).
  48. * Ideally RTCs use that same time; but PCs can't do that
  49. * if they need to boot MS-Windows. Messy...
  50. *
  51. * When running in utc mode this process's timezone is UTC,
  52. * so we'll pass a UTC date to the RTC.
  53. *
  54. * Else mode is local so the time given to the RTC
  55. * will instead use the local time zone.
  56. */
  57. ptm = localtime(wakeup);
  58. wake.time.tm_sec = ptm->tm_sec;
  59. wake.time.tm_min = ptm->tm_min;
  60. wake.time.tm_hour = ptm->tm_hour;
  61. wake.time.tm_mday = ptm->tm_mday;
  62. wake.time.tm_mon = ptm->tm_mon;
  63. wake.time.tm_year = ptm->tm_year;
  64. /* wday, yday, and isdst fields are unused by Linux */
  65. wake.time.tm_wday = -1;
  66. wake.time.tm_yday = -1;
  67. wake.time.tm_isdst = -1;
  68. /* many rtc alarms only support up to 24 hours from 'now',
  69. * so use the "more than 24 hours" request only if we must
  70. */
  71. if ((rtc_time + (24 * 60 * 60)) > *wakeup) {
  72. xioctl(fd, RTC_ALM_SET, &wake.time);
  73. xioctl(fd, RTC_AIE_ON, 0);
  74. } else {
  75. /* avoid an extra AIE_ON call */
  76. wake.enabled = 1;
  77. xioctl(fd, RTC_WKALM_SET, &wake);
  78. }
  79. }
  80. #define RTCWAKE_OPT_AUTO 0x01
  81. #define RTCWAKE_OPT_LOCAL 0x02
  82. #define RTCWAKE_OPT_UTC 0x04
  83. #define RTCWAKE_OPT_DEVICE 0x08
  84. #define RTCWAKE_OPT_SUSPEND_MODE 0x10
  85. #define RTCWAKE_OPT_SECONDS 0x20
  86. #define RTCWAKE_OPT_TIME 0x40
  87. int rtcwake_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  88. int rtcwake_main(int argc UNUSED_PARAM, char **argv)
  89. {
  90. time_t rtc_time;
  91. unsigned opt;
  92. const char *rtcname = NULL;
  93. const char *suspend;
  94. const char *opt_seconds;
  95. const char *opt_time;
  96. time_t sys_time;
  97. time_t alarm_time = 0;
  98. unsigned seconds = 0;
  99. int utc = -1;
  100. int fd;
  101. #if ENABLE_LONG_OPTS
  102. static const char rtcwake_longopts[] ALIGN1 =
  103. "auto\0" No_argument "a"
  104. "local\0" No_argument "l"
  105. "utc\0" No_argument "u"
  106. "device\0" Required_argument "d"
  107. "mode\0" Required_argument "m"
  108. "seconds\0" Required_argument "s"
  109. "time\0" Required_argument "t"
  110. ;
  111. applet_long_options = rtcwake_longopts;
  112. #endif
  113. opt = getopt32(argv, "alud:m:s:t:", &rtcname, &suspend, &opt_seconds, &opt_time);
  114. /* this is the default
  115. if (opt & RTCWAKE_OPT_AUTO)
  116. utc = -1;
  117. */
  118. if (opt & (RTCWAKE_OPT_UTC | RTCWAKE_OPT_LOCAL))
  119. utc = opt & RTCWAKE_OPT_UTC;
  120. if (!(opt & RTCWAKE_OPT_SUSPEND_MODE))
  121. suspend = DEFAULT_MODE;
  122. if (opt & RTCWAKE_OPT_SECONDS)
  123. /* alarm time, seconds-to-sleep (relative) */
  124. seconds = xatoi(opt_seconds);
  125. if (opt & RTCWAKE_OPT_TIME)
  126. /* alarm time, time_t (absolute, seconds since 1/1 1970 UTC) */
  127. alarm_time = xatol(opt_time);
  128. if (!alarm_time && !seconds)
  129. bb_error_msg_and_die("must provide wake time");
  130. if (utc == -1)
  131. utc = rtc_adjtime_is_utc();
  132. /* the rtcname is relative to /dev */
  133. xchdir("/dev");
  134. /* this RTC must exist and (if we'll sleep) be wakeup-enabled */
  135. fd = rtc_xopen(&rtcname, O_RDONLY);
  136. if (strcmp(suspend, "on") && !may_wakeup(rtcname))
  137. bb_error_msg_and_die("%s not enabled for wakeup events", rtcname);
  138. /* relative or absolute alarm time, normalized to time_t */
  139. sys_time = time(NULL);
  140. {
  141. struct tm tm_time;
  142. rtc_read_tm(&tm_time, fd);
  143. rtc_time = rtc_tm2time(&tm_time, utc);
  144. }
  145. if (alarm_time) {
  146. if (alarm_time < sys_time)
  147. bb_error_msg_and_die("time doesn't go backward to %s", ctime(&alarm_time));
  148. alarm_time += sys_time - rtc_time;
  149. } else
  150. alarm_time = rtc_time + seconds + 1;
  151. setup_alarm(fd, &alarm_time, rtc_time);
  152. sync();
  153. printf("wakeup from \"%s\" at %s", suspend, ctime(&alarm_time));
  154. fflush_all();
  155. usleep(10 * 1000);
  156. if (strcmp(suspend, "on"))
  157. xopen_xwrite_close(SYS_POWER_PATH, suspend);
  158. else {
  159. /* "fake" suspend ... we'll do the delay ourselves */
  160. unsigned long data;
  161. do {
  162. ssize_t ret = safe_read(fd, &data, sizeof(data));
  163. if (ret < 0) {
  164. bb_perror_msg("rtc read");
  165. break;
  166. }
  167. } while (!(data & RTC_AF));
  168. }
  169. xioctl(fd, RTC_AIE_OFF, 0);
  170. if (ENABLE_FEATURE_CLEAN_UP)
  171. close(fd);
  172. return EXIT_SUCCESS;
  173. }