Hello I'm wanting to write a data validation to a cell using VBA (Know how to do this part)

I need to limit the cell to a positive whole number that must be greater than or equal to the cell immediately above it.

So A1 would just be data validation for a positive whole number (got this part)
A2 is the custom one I'm working on/need help with

Ex. Passes
A1=3
A2=5

Ex. Fails because A2 is not greater than or equal to A1
A1=3
A2=1

Thoughts?