Function rtc_ioctl 

pub fn rtc_ioctl(cmd: u32, arg: u64) -> i32

Perform an RTC ioctl operation.

Supported commands:

• RTC_ALM_SET: Set alarm time (arg interpreted as &RtcAlarm)
• RTC_AIE_ON: Enable alarm interrupt
• RTC_AIE_OFF: Disable alarm interrupt

Returns 0 on success, -1 on invalid command.