How to read back EPCS64 flash data by FPGA after its configuration

we have a customised FPGA board having FPGA EP3C120****.Flash Device connected this fpga is EPCS64.

It is working fine with AS mode flashing and configuration is happening to FPGA in every power on as per standard.

we want to Read the content of Flash after its configuration like reading a memory from its starting address.

This Flash is interface to FPGA with following Pins (DCLK, NCS0, ASDO, Data0). please suggest the method to read back the flash.