In reply to Anudeep J:
A register might consist of several reg fields. If this is the case you have to define your reg fields by extendending the base class uvm_reg_field. The base class ha s lot of methods available to deal with this reg field, including methosd to set the access policy. All what you have available for the reg field is also available for the reg itself. If you have single reg fields you have to construct your regs form the reg fields. For more details see the UVM reference guide.