timed: set valid flag (commaai#32061)

* timed: set valid flag

* oops

common/time.py

@@ -1,6 +1,15 @@
 import datetime
+from pathlib import Path
 
-MIN_DATE = datetime.datetime(year=2024, month=1, day=28)
+_MIN_DATE = datetime.datetime(year=2024, month=3, day=30)
+
+def min_date():
+  # on systemd systems, the default time is the systemd build time
+  systemd_path = Path("/lib/systemd/systemd")
+  if systemd_path.exists():
+    d = datetime.datetime.fromtimestamp(systemd_path.stat().st_mtime)
+    return d + datetime.timedelta(days=1)
+  return _MIN_DATE
 
 def system_time_valid():
-  return datetime.datetime.now() > MIN_DATE
+  return datetime.datetime.now() > min_date()

system/timed.py

@@ -8,6 +8,7 @@
 from timezonefinder import TimezoneFinder
 
 import cereal.messaging as messaging
+from openpilot.common.time import system_time_valid
 from openpilot.common.params import Params
 from openpilot.common.swaglog import cloudlog
 from openpilot.system.hardware import AGNOS
@@ -69,7 +70,8 @@ def main() -> NoReturn:
   while True:
     sm.update(1000)
 
-    msg = messaging.new_message('clocks', valid=True)
+    msg = messaging.new_message('clocks')
+    msg.valid = system_time_valid()
     msg.clocks.wallTimeNanos = time.time_ns()
     pm.send('clocks', msg)