OCP VIP + QP become a Reference Model
In this case, a user proprietary assertion based model is validated and qualified against the OCP VIP reference model using a per-profile approach.

As shown in Figure 4 below, The assertion based model is typically not configurable and a new model version must be designed each time the customer changes the profile. After configuring the OCP VIP reference models (master and slave) in the proper manner, according to the model profile to validate, a regression test is executed.

This process is similar to that adopted for the OCP VIP and it is mainly based on the protocol checker. In fact this element of the reference OCP VIP has been tested in a faulty and non-faulty environment, in other words with and without protocol errors and the objective was to see only the expected error messages or not to see any error message. In the same way, for the user's defined assertion model, protocol errors are injected during the simulation in order to activate all the interested OCP checks that are also present in the new model under verification.

Figure 4 - Verification flow to achieve comprehensive regression process for qualification of Yogitech's OCP VIP

Errors generated by the model under qualification are then compared against those resulting from the reference model and they must correspond. In this case the regression process is iterated twice, with and without protocol fault injections, in order to assure that all the OCP rules allowed for the profile have been properly implemented into the model under test (avoid false positive in the user simulation) and all of them are semantically correct (avoid false negative in the user simulation).

The process can be easily executed on a unique robust OCP VIP, every time a new assertion model is created for a specific OCP profile, instead of creating application specific versions or design specific derivatives of the OCP VIP, with the consequential divergence of maintenance issues.

OCP VIP trustful migration from "e" to System Verilog
It is not so obvious that the quality and maturity of a VIP can be automatically inherited by new VIP targeting the same protocol. The protocol knowledge and the VIP coverage respect to all the allowed and possible configurations are embedded in the product and it is not so banal to export to a new VIP.

The OCP VIP regression test suite is by construction complete enough to cover almost all the OCP features and interfaces with a reasonable number of tests and then it can guarantee that also the new VIP in a different verification language, for instance in System Verilog, will be complete and will have the same level of maturity.

Taking into account that technologies able to automatically or semi-automatically wrap a native e-language core are available, this process of quality migration can be divided in two steps. During a first step the OCP VIP implemented by using the e-language (OCP eVC in the following), qualified as core technology with the previously mentioned methodology for the Qualification Process, is used as a proven and reliable model that can be wrapped and used in a multi-language verification environments.

In the second step, the wrapped eVC and the OCP qualification process are used as reference model and regression test suite to validate another OCP VIP implemented in a different native language.

Figure 5 below shows the two steps performed to port an e VIP in a native System Verilog solution with the goal to transfer the level of maturity of the reference VIP into the new one.

Figure 5 " A practical case: how Yogitech regression suite enable a robust transfer of maturity through a technology transition

During the first step the core technology (eVC) is wrapped in order to get a System Verilog equivalent VIP. This VIP is usable into a System Verilog environment with no evidence of the e embedded core. This process is automatic and it also includes the translation for sequences or transactions used in the tests.

In the second step the new "wrapped" VIP is used as a reference model to validate the System Verilog native solution. It is connected side-to-side to the System Verilog VIP, one time acting as a Master that initiates and drives OCP traffic and one time acting as a slave that reacts to OCP traffic initiated by the new VIP. The second step is then applied twice inverting the master and the slave to qualify both the agents.

The silicon-proven core technology of the OCP eVC/uVC, well preserved by means of the Qualification Process presented here, makes that both quality and robustness of the e model are transferred also to other solutions enabling robust and flexible VIP usage in a mixed language verification environment.

Angelo Diblasi is currently a senior verification engineer, Yogitech, in the Verification Solutions Business. In this role, he is responsible for the verification methodology and of the company's OCP Verification IP. He leads a team that has gathered many years of experience supporting multiple world-class companies in deploying OCP eVC in their Verification flow.

Stefano Lorenzini is Engineering Manager at Yogitech and leads design teams carrying out activities at both company's business lines of Verification Solutions and "faultRobust Technology". Stefano has gathered more than 12 years of experience in semiconductor industries as Alcatel and ST, where he was managing ADSL and Gateway programs based on embedded multiprocessors and custom DSPs.

Gabriele Orlandi is General Manager at Yogitech; as interim manager of the Verification Solutions business unit, he takes care of the relationship with company's VIP licensees and selects market feedback to be included into products' roadmap. Before joining Yogitech, Gabriele was a consultant of Italian industries and Research Institutes for business innovation and technology-based initiatives.