[TF-A] What Doc / NDA doc do I need when I want to add a new platfrom in TF-A / OPTEE? (i.e., RK3566 )

Hello, Everyone,

If I want to add a new platform support in TF-A for RK3566 as an example, what Documentation do I need to read.

Using RK3399 as a contrast ( because most of RK3399 doc is opened in internet ), we already know this SoC is supported in OPTEE and TF-A. And I can get RK3399 Docs:* TRM V1.3 Part 1*, T*RM V1.3 Part2*, *TRM V1.4 Part 1*, *Datasheet V2.1*. I can see in *TRM chapter 16 System Security, *there are some descriptions about system security, and references to other system registers, like *SGRF, *etc, but it still seems to me insufficiently ( No SGRF description ) to finish a full support platform implementation in TF-A. Some people said I need to sign an NDA with Rockchip to get Security related part docs. But when I reach to Rockchip, they said all docs are opened already, No NDA options. When I talked to one partner/distributor of Rockchip, only security related doc is also some doc I can find on internet.

So I am curious and confused, can I, as a third party developer, develop a new platform implementation for TF-A / OPTEE ( specially for Rockchip Platform )?

Thanks