Hi Ganesh,
I.MX UART for RS485 function is supported by imx.c , which is in path drivers/tty/serial/imx.c , which realize how to control receiving and transmitting data via CTS pin(dce) or RTS(dte).
here is imx.c source code:
imx.c\serial\tty\drivers - linux-imx - i.MX Linux kernel
Here is discussions on RS485:
Strange RS485 latency of disabling driver.
https://community.nxp.com/message/1050866
Hope these informatin can help you.
Have a nice day!
BR,
Weidong