From ee87261cd5d29ff11648f32c3dda7d85b653893e Mon Sep 17 00:00:00 2001
From: whoisdomi <dcantu83@gmail.com>
Date: Sat, 19 Sep 2026 15:16:01 -0500
Subject: [PATCH] Car Date/Time fallback when gps/wifi not available

---
 system/timed.py | 84 ++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 80 insertions(+), 4 deletions(-)

diff --git a/system/timed.py b/system/timed.py
index 64fd592524..9ed5176283 100644
--- a/system/timed.py
+++ b/system/timed.py
@@ -17,6 +17,67 @@ try:
 except Exception:
   TimezoneFinder = None
 
+try:
+  from zoneinfo import ZoneInfo
+except Exception:
+  ZoneInfo = None
+
+# StarPilot variables
+# Hyundai/Kia cluster wall clock, local time. Fallback when GPS has no fix.
+CAR_CLOCK_ADDR = 0x4F0
+CAR_CLOCK_BUS = 1
+
+
+def parse_car_clock(dat: bytes):
+  # cluster sends all 0xFF until initialized
+  if len(dat) < 7:
+    return None
+  if all(b == 0xFF for b in dat) or all(b == 0 for b in dat):
+    return None
+
+  hour, minute, second = dat[1], dat[2], dat[3]
+  month = (dat[4] >> 2) & 0x0F
+  year = 2000 + dat[5]
+  day = dat[6]
+
+  try:
+    return datetime.datetime(year, month, day, hour, minute, second)
+  except ValueError:
+    return None
+
+
+def read_car_clock(can_sock, timezone):
+  latest = None
+  for msg in messaging.drain_sock(can_sock):
+    for frame in msg.can:
+      if frame.address == CAR_CLOCK_ADDR and frame.src == CAR_CLOCK_BUS:
+        parsed = parse_car_clock(bytes(frame.dat))
+        if parsed is not None:
+          latest = parsed
+
+  if latest is None:
+    return None
+
+  utc = car_clock_to_utc(latest, timezone)
+  if utc is None or not (min_date() <= utc <= MAX_DATE):
+    return None
+  return utc
+
+
+def car_clock_to_utc(local_dt, timezone):
+  # timezone comes from the last GPS fix, so this needs one to have happened once
+  if ZoneInfo is None or not timezone:
+    return None
+  if isinstance(timezone, bytes):
+    timezone = timezone.decode("utf-8", errors="replace")
+  try:
+    tz = ZoneInfo(timezone)
+  except Exception:
+    cloudlog.exception("timed.bad_timezone")
+    return None
+  # fold=0: on the duplicated hour of a DST fall back, assume the first pass
+  return local_dt.replace(tzinfo=tz, fold=0).astimezone(datetime.UTC).replace(tzinfo=None)
+
 
 def set_time(new_time):
   diff = datetime.datetime.now(datetime.UTC).replace(tzinfo=None) - new_time
@@ -64,10 +125,13 @@ def main() -> NoReturn:
 
   pm = messaging.PubMaster(['clocks'])
   sm = messaging.SubMaster([gps_location_service])
+  # StarPilot variables
+  can_sock = messaging.sub_sock('can', timeout=100)
 
   # StarPilot variables
   tf = TimezoneFinder() if TimezoneFinder is not None else None
   timezonefinder_logged = False
+  car_clock_tz_logged = False
 
   last_timezone = params.get("Timezone")
   if last_timezone is not None:
@@ -83,11 +147,23 @@ def main() -> NoReturn:
 
     gps = sm[gps_location_service]
     gps_time = datetime.datetime.fromtimestamp(gps.unixTimestampMillis / 1000., datetime.UTC).replace(tzinfo=None)
-    if not sm.updated[gps_location_service] or (time.monotonic() - sm.logMonoTime[gps_location_service] / 1e9) > 2.0:
+    gps_usable = (sm.updated[gps_location_service] and
+                  (time.monotonic() - sm.logMonoTime[gps_location_service] / 1e9) <= 2.0 and
+                  gps.hasFix and min_date() <= gps_time <= MAX_DATE)
+
+    # StarPilot variables
+    # only corrects an invalid clock, so GPS and NTP always win
+    if not gps_usable and not system_time_valid():
+      if not last_timezone and not car_clock_tz_logged:
+        cloudlog.warning("timed: no saved timezone, cannot use car clock fallback")
+        car_clock_tz_logged = True
+      car_time = read_car_clock(can_sock, last_timezone)
+      if car_time is not None:
+        cloudlog.warning(f"timed: setting time from car clock: {car_time}")
+        set_time(car_time)
       continue
-    if not gps.hasFix:
-      continue
-    if gps_time < min_date() or gps_time > MAX_DATE:
+
+    if not gps_usable:
       continue
 
     set_time(gps_time)