Using the Module Reference feature of the Vivado IP integrator you can quickly add a module or entity defined in an HDL source file directly into your BD. To add an RTL module, the source file must already be loaded into the project, as described at this link in the Vivado Design Suite User Guide: System-Level Design Entry (UG895).
From within the BD select the Add Module command from the right-click or context menu of the design canvas. The Add Module dialog box displays a list of all valid modules defined in the RTL source files that you have previously added to the project.
Select one from the list to instantiate it into the BD. The Vivado tools add the module to the BD, and you can make connections to it just as you would with any other IP in the design. The added RTL module displays in the BD with special markings that identify it as an RTL referenced module, as shown in the following figure. This is also referred to as RTL on Canvas. See Referencing RTL Modules, for more information on this feature.