RFSoC 4x2 CLK_IN, SYNC_IN, and 1PPS ports

There is some good information on the purpose of these ports in the RFSoC4x2 reference manual, along with some advice on how to use them. Additionally, you can have a look at the schematic to follow where these ports lead to.

Both these documents can be found here, under the resources section at the bottom of the page.