UART configuration for AT commands for HL7692


I have HL7692 wireless module and connected it to ARM Host running Android 5.1 via USB 2.0.
Following the Android RIL Integration Guide 1.1, i can able to send / receive responses for AT commands over USB (wwan0) Interface (ttyACM0).

Which UART interface is configured for communicating AT commands via UART???

I think UART1 can be used to AT command.

Can drivers/tty/serial/n_gsm.c module be used to control HL-7692 module.

Over all goal is to communicate HL-76XX module via AT-commands over tty serial interface for asynchronous communication.