The UART APIs provide a set of functions for using the Quessence™ UART modules. Functions are provided to configure and control the UART modules either synchronously or asynchronously, to send and receive data, and to manage interrupts for the UART modules.

Below is the link for CMSIS supported usart APIs:

http://www.keil.com/pack/doc/CMSIS/Driver/html/group__usart__interface__gr.html