Implement RTC detection for devices that have it (newer MM+)

[tGecko]

Since the newest hardware revisions of the Miyoo Mini+ have RTC, it should be handled accordingly.

Detects if RTC is present, and does not restore and/or advance time if it is.
Works with newest Miyoo Mini+ with built in RTC as well as modded in RTC.

Edit: will also work on MM with RTC, see #1673

[khalid151]

Wouldn't it make more sense to check if the hardware exists instead of this threshold?

You can check that on /sys/class/rtc, or find it on /dev/rtcX. Though, I'm not sure if devices without RTC have a dummy RTC dev node. The only MM+ I got a week ago does have a RTC.

[khalid151]

This is what I'm currently using on my device to update system's time:

diff --git a/static/build/.tmp_update/runtime.sh b/static/build/.tmp_update/runtime.sh
index 1ea12957..154356f6 100644
--- a/static/build/.tmp_update/runtime.sh
+++ b/static/build/.tmp_update/runtime.sh
@@ -25,7 +25,13 @@ main() {
     clear_logs
 
     init_system
-    update_time
+    # check if a device node for the RTC exists
+    if [ -e /dev/rtc0 ]; then
+        # updating time using RTC
+        hwclock -s
+    else
+        update_time
+    fi
 
     # Remount passwd/group to add our own users
     mount -o bind $sysdir/config/passwd /etc/passwd

But I've set the RTC (after updating the system's time on network) through terminal with hwclock -w.
Clock app should be able to set that automatically.

[tGecko]

Wouldn't it make more sense to check if the hardware exists instead of this threshold?

You can check that on /sys/class/rtc, or find it on /dev/rtcX. Though, I'm not sure if devices without RTC have a dummy RTC dev node. The only MM+ I got a week ago does have a RTC.

The RTC hardware always existed, it's part of the SoC. Older units just had it wired to the same voltage rail as the chip itself, so it wouldn't be powered when the device was off.

See https://github.com/anzz1/miyoomini-resources/wiki/Hardware-Mod:-RTC-on-the-Miyoo-Mini-Plus---Miyoo-Mini

[khalid151]

Oh, my bad, I should've checked. Thanks for the link.