Add rtcwake.

Some of the bringup folks are debugging RTC issues and asked for this.

Rather than duplicate the weird xtzset dance with mktime, I've factored
that out into a new xmktime that takes a boolean for whether to use UTC
or local time.

Otherwise, the slight cleanup of hwclock.c is entirely optional. The
only functional change there is that util-linux 2.34's hwclock uses ISO
time format, which is the usual toybox preference anyway, so I've
switched it over to that rather than ctime(3).

Bug: http://b/152042947

1 files changed, 134 insertions, 0 deletions

diff --git a/toys/pending/rtcwake.c b/toys/pending/rtcwake.c
new file mode 100644
index 00000000..0929d51f
--- /dev/null
+++ b/toys/pending/rtcwake.c
@@ -0,0 +1,134 @@
+/* rtcwake.c - enter sleep state until given time.
+ *
+ * Copyright 2020 The Android Open Source Project
+
+USE_RTCWAKE(NEWTOY(rtcwake, "(list-modes);(auto)a(device)d:(local)l(mode)m:(seconds)s#(time)t#(utc)u(verbose)v[!alu]", TOYFLAG_USR|TOYFLAG_BIN))
+
+config RTCWAKE
+  bool "rtcwake"
+  default n
+  help
+    usage: rtcwake [-aluv] [-d FILE] [-m MODE] [-s SECS] [-t UNIX]
+
+    Enter the given sleep state until the given time.
+
+    -a	RTC uses time specified in /etc/adjtime
+    -d FILE	Device to use (default /dev/rtc)
+    -l	RTC uses local time
+    -m	Mode (--list-modes to see those supported by your kernel):
+    	  disable  Cancel current alarm
+    	  freeze   Freeze processes, idle processors
+    	  disk     S4: suspend to disk
+    	  mem      S3: suspend to RAM
+    	  no       Don't suspend, just set wakeup time
+    	  off      S5: power off
+    	  on       Don't suspend, poll RTC for alarm
+    	  show     Don't suspend, just show current alarm
+    	  standby  S1: default
+    -s SECS	Wake SECS seconds from now
+    -t UNIX	Wake UNIX seconds from epoch
+    -u	RTC uses UTC
+    -v	Verbose
+*/
+
+#define FOR_rtcwake
+#include "toys.h"
+
+GLOBALS(
+  long long t, s;
+  char *m, *d;
+
+  struct rtc_wkalrm alarm;
+)
+
+void rtcwake_main(void)
+{
+  time_t now, rtc_now, then;
+  struct tm rtc_tm;
+  int fd, utc;
+
+  if (FLAG(list_modes)) {
+    xreadfile("/sys/power/state", toybuf, sizeof(toybuf));
+    printf("off no on disable show %s", toybuf);
+    return;
+  }
+
+  // util-linux defaults to "suspend", even though I don't have anything that
+  // supports that (testing everything from a ~2010 laptop to a 2019 desktop).
+  if (!TT.m) TT.m = "suspend";
+
+  if (FLAG(u)) utc = 1;
+  else if (FLAG(l)) utc = 0;
+  else {
+    xreadfile("/etc/adjtime", toybuf, sizeof(toybuf));
+    utc = !!strstr(toybuf, "UTC");
+  }
+  if (FLAG(v)) xprintf("RTC time: %s\n", utc ? "UTC" : "local");
+
+  if (!TT.d) TT.d = "/dev/rtc0";
+  if (FLAG(v)) xprintf("Device: %s\n", TT.d);
+  fd = xopen(TT.d, O_RDWR);
+
+  now = time(0);
+  xioctl(fd, RTC_RD_TIME, &rtc_tm);
+  rtc_now = xmktime(&rtc_tm, utc);
+  if (FLAG(v)) {
+    xprintf("System time:\t%lld / %s", (long long)now, ctime(&now));
+    xprintf("RTC time:\t%lld / %s", (long long)rtc_now, ctime(&rtc_now));
+  }
+
+  if (!strcmp(TT.m, "show")) { // Don't suspend, just show current alarm.
+    xioctl(fd, RTC_WKALM_RD, &TT.alarm);
+    if (!TT.alarm.enabled) xputs("alarm: off");
+    else {
+      if ((then = mktime((void *)&TT.alarm.time)) < 0) perror_exit("mktime");
+      xprintf("alarm: on %s", ctime(&then));
+    }
+    goto done;
+  } else if (!strcmp(TT.m, "disable")) { // Cancel current alarm.
+    xioctl(fd, RTC_WKALM_RD, &TT.alarm);
+    TT.alarm.enabled = 0;
+    xioctl(fd, RTC_WKALM_SET, &TT.alarm);
+    goto done;
+  }
+
+  if (FLAG(s)) {
+    then = rtc_now + TT.s + 1; // strace shows util-linux adds 1.
+  } else if (FLAG(t)) {
+    then = TT.t + (rtc_now - now);
+    if (then<=rtc_now) error_exit("rtc %lld >= %lld", (long long)rtc_now, TT.t);
+  } else help_exit("-m %s needs -s or -t", TT.m);
+  if (FLAG(v)) xprintf("Wake time:\t%lld / %s", (long long)then, ctime(&then));
+
+  if (!(utc ? gmtime_r : localtime_r)(&then, (void *)&TT.alarm.time))
+    error_exit(utc ? "gmtime_r failed" : "localtime_r failed");
+
+  TT.alarm.enabled = 1;
+  xioctl(fd, RTC_WKALM_SET, &TT.alarm);
+  sync();
+
+  xprintf("wakeup using \"%s\" from %s at %s", TT.m, TT.d, ctime(&then));
+  msleep(10);
+
+  if (!strcmp(TT.m, "no")) { // Don't suspend, just set wakeup time.
+  } else if (!strcmp(TT.m, "on")) { // Don't suspend, poll RTC for alarm.
+    unsigned long data = 0;
+
+    if (FLAG(v)) xputs("Reading RTC...");
+    while (!(data & RTC_AF)) {
+      if (read(fd, &data, sizeof(data)) != sizeof(data)) perror_exit("read");
+      if (FLAG(v)) xprintf("... %s: %lx\n", TT.d, data);
+    }
+  } else if (!strcmp(TT.m, "off")) {
+    xexec((char *[]){"poweroff", 0});
+  } else {
+    // Everything else lands here for one final step. The write will fail with
+    // EINVAL if the mode is not supported.
+    int fd = xopen("/sys/power/state", O_WRONLY);
+
+    xwrite(fd, TT.m, strlen(TT.m));
+    close(fd);
+  }
+done:
+  close(fd);
+}