Golang，使用子包中主包的结构或功能(Golang, Using a Structure or function of a main package from a sub package)

I am trying to write a go project with several sub projects. For an simple example the project looks like this

Main
 |- package one
    |- package one.one
    |- package one.two
 |- package two

From my main package i can use any function or structure of any sub package By importing them. But My question is how can i access an struct or function of main from any sub package.