Setting timer/counter in the Arm TrustZone

Question

My goal is to set a counter/timer in the secure world that cannot be disabled from the normal world. When the timer expires, it raises an interrupt that will be handled by the secure world. Is it possible?

UPDATE: I have found OP TEE os project and in particular the way they handle timers and secure world interrupts is pretty much what I need. I am looking inot better understanding this now:

https://github.com/OP-TEE/optee_os/blob/master/core/arch/arm/pta/interrupt_tests.c

Answer 1

I think the secure timer and related registers CNTPS_*_EL1 are what you want.