To make this process scalable and easier for developers ARM has created the TrustZone Ready Program that brings together industry security needs and translates them into system requirements and checklists. The TrustZone Ready Program is a simple Partner agreement that provides access to a comprehensive set of design blueprints, market requirements and checklists providing an essential design resource for ARM Partners wanting to implement system wide security in their next platform.
You can find out more about the TrustZone Ready Program by viewing this overview or by contacting ARM and discussing the program in more detail. An overview of the TrustZone Ready Program can be found here.
The interface between the TEE and the Rich OS, called the TEE Client API, was standardized by GlobalPlatform in 2010. The TEE Internal API between the Trusted Application and the Trusted OS was completed in 2011.
A TEE can support multiple Trusted Applications developed by different providers that execute independently from each other. Trusted Applications are given controlled access to security resources and services via the TEE Internal API. Examples of TEE Secure services include key storage and management, cryptography, secure clock, Trusted User Interface.