Matlab Function block to define Steady Space model (controller)

Hello every one

I have Steady-Space model(Controller) as below:

A =[ *M* ]; B =[0 0 2 0 0 0 0];;
C =[0;2;0]; D =[0 2 0 0 0 0 0 ; 2 0 2 0 0 0 0 ;  0 0 0 *M* 0 2 0] 

    Controller =ss(A,B,C,D)

This controller have 7 inputs and 3 outputs.

I don't want to use simulink steady-space block to define this controller in it.

I have * variable M in my controller that can be changed with time and I want to use

variable parameter to have variable steady-space controller.

How can I use user defined blocks to write this variable steady-space controller ?

Which User defined blocks can be use for programming and how ?

Thanks for your help