How to set the filter, gain and read the RSSI

Hi all,

     I had realized the point to point communication of AD9361. But in my program I don't know how to set the lowpass filter, hardware gain(TX and RX) which used to increase the transmission distance, and how to read the RSSI value? Even though ADI  provides the libiio and it's API in linux, I still don't know how to use these functions, because I don't now the name of these parameters, and the register name or address. Where can I find the parameters's name? Such as hardware gain, and how to set the filter? Thank you!