Auto-detect RTC device (/dev/rtc0,/dev/rtc1) for hwclock sync

src/rtc_sync.py

@@ -1,7 +1,7 @@
 import os
 import subprocess
 from datetime import datetime, timezone
-from typing import Tuple
+from typing import Optional, Tuple
 
 import ntplib
 
@@ -13,21 +13,34 @@ class RTCAndNTPManager:
         self.state = state
         self.rtc_device = rtc_device
         self.ntp_server = ntp_server
+        self._resolved_rtc_device: Optional[str] = None
 
     def _run(self, args, timeout: int = 12) -> subprocess.CompletedProcess:
         return subprocess.run(args, capture_output=True, text=True, timeout=timeout, check=False)
 
+    def _resolve_rtc_device(self) -> Optional[str]:
+        if self._resolved_rtc_device and os.path.exists(self._resolved_rtc_device):
+            return self._resolved_rtc_device
+
+        candidates = [self.rtc_device, "/dev/rtc", "/dev/rtc0", "/dev/rtc1"]
+        for candidate in candidates:
+            if os.path.exists(candidate):
+                self._resolved_rtc_device = candidate
+                return candidate
+        return None
+
     def rtc_available(self) -> bool:
-        return os.path.exists(self.rtc_device)
+        return self._resolve_rtc_device() is not None
 
     def sync_from_rtc(self) -> Tuple[bool, str]:
-        if not self.rtc_available():
-            return False, f"RTC not found at {self.rtc_device}"
+        rtc_device = self._resolve_rtc_device()
+        if rtc_device is None:
+            return False, f"RTC not found (checked: {self.rtc_device}, /dev/rtc, /dev/rtc0, /dev/rtc1)"
 
-        proc = self._run(["hwclock", "-s", "--utc"], timeout=10)
+        proc = self._run(["hwclock", "-s", "--utc", "--rtc", rtc_device], timeout=10)
         if proc.returncode == 0:
-            self.state.update_status("System time loaded from RTC", "")
-            return True, "RTC -> system time ok"
+            self.state.update_status(f"System time loaded from {rtc_device}", "")
+            return True, f"{rtc_device} -> system time ok"
         return False, (proc.stderr or proc.stdout or "hwclock -s failed").strip()
 
     def sync_ntp_to_system(self, timeout: int = 6) -> Tuple[bool, str]:
@@ -48,13 +61,14 @@ class RTCAndNTPManager:
             return False, f"NTP sync failed: {exc}"
 
     def write_system_time_to_rtc(self) -> Tuple[bool, str]:
-        if not self.rtc_available():
-            return False, f"RTC not found at {self.rtc_device}"
+        rtc_device = self._resolve_rtc_device()
+        if rtc_device is None:
+            return False, f"RTC not found (checked: {self.rtc_device}, /dev/rtc, /dev/rtc0, /dev/rtc1)"
 
-        proc = self._run(["hwclock", "-w", "--utc"], timeout=10)
+        proc = self._run(["hwclock", "-w", "--utc", "--rtc", rtc_device], timeout=10)
         if proc.returncode == 0:
-            self.state.update_status("RTC updated from system time", "")
-            return True, "system -> RTC ok"
+            self.state.update_status(f"{rtc_device} updated from system time", "")
+            return True, f"system -> {rtc_device} ok"
         return False, (proc.stderr or proc.stdout or "hwclock -w failed").strip()
 
     def sync_ntp_and_rtc(self) -> Tuple[bool, str]: