A Test Access Mechanism (TAM) architecture for facilitating testing of IP blocks integrated on a System on a Chip (SoC). The TAM architecture includes a Test Controller and one or more Test Wrappers that are integrated on the SoC proximate to IP blocks. Test data and commands corresponding to input from an external tester are packaged by the Test Controller and sent to the Test Wrappers via an interconnect fabric. The Test Wrappers employ one or more test ports to provide test data, control, and/or stimulus signals to the IP block to facilitate circuit-level testing of the IP block. Test results for the circuit-level tests are returned to the Test Controller via the fabric. Test Wrappers may be configured to pass through interconnect signals, enabling functional testing of IP blocks to be facilitated via test packages and test results transmitted between the Test Controller and the IP blocks via the fabric.