How to read hardware registers from TA

[arunlalkm-intel]

My use case is that I want to read chip ID in TA.

Just like in Linux we read using /dev/mem is there a way to read hardware registers from TA?

[ivila]

I think it depends on the chip provider, for example, if you are using rockchip, you can check the rockchip_cpuinfo_probe method, it use dts to find the register, and read the information from efuse, you can follow the logic and do the same thing in TEE.

[jenswi-linaro]

The short answer is, no. But if you need it anyway you must do it via pseudo TA. Have you considered PTA_SYSTEM_DERIVE_TA_UNIQUE_KEY from the system PTA?

[arunlalkm-intel]

Thanks for suggestions. I am using PTA_SYSTEM_DERIVE_TA_UNIQUE_KEY but that gives me only HUK based key.

[jenswi-linaro]

A pseudo-TA for chip ID is your only option then. If the chip ID is sensitive you'll need to add some filtering so only the expected TAs are allowed to get hold of it.

[arunlalkm-intel]

I am unfamiliar with pseudo-TA. It will be helpful if you can give bit more details or point me to an example.

[jenswi-linaro]

https://optee.readthedocs.io/en/latest/architecture/trusted_applications.html#pseudo-trusted-applications