project update from serial port

I am using BL4S200 for my project. I have question about the upgrade of my project. I am using serial communication with PC host. I will build my UI for my project control. however, I want to use serial communication port (like port C,port E or port F) to upgrade my program, I know I can use programming port. but I don't want end user to use it. I need another port for firmware update purpose. I find some examples, but it is through ethernet. In my project, I can't use ethernet, Is it possible to send new firmware to controller via serial port (not programming port)?