rtc-tssupervisor: Things to investigate

[ts-kris]

Implement newer ioctl()s

Somewhere between util-linux 2.36.1 and 2.38.1, hwclock rolled out the --param-* flags which uses the RTC_PARAM_GET/SET ioctl()s:

root@tsimx6ul:~# hwclock --help
...
Arguments:
 <param> is either a numeric RTC parameter value or one of these aliases:
   - features: supported features (0x0)
   - correction: time correction (0x1)
   - bsm: backup switch mode (0x2)
   See Kernel's include/uapi/linux/rtc.h for parameters and values.

root@tsimx6ul:~# hwclock --param-get features
hwclock: ioctl(3, RTC_PARAM_GET, param) to /dev/rtc0 failed: Inappropriate ioctl for device
hwclock: unable to read the RTC parameter features
root@tsimx6ul:~# hwclock --param-get correction
hwclock: ioctl(3, RTC_PARAM_GET, param) to /dev/rtc0 failed: Inappropriate ioctl for device
hwclock: unable to read the RTC parameter correction

Investigate kernel alarmtimer support

e.g. kernel/time/alarmtimer.c has RTC hooks and tests for features like RTC_FEATURE_ALARM