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USBDEV DV document

Goals

  • DV
    • Verify all USBDEV IP features by running dynamic simulations with a SV/UVM based testbench.
    • Develop and run all tests based on the testplan below towards closing code and functional coverage on the IP and all of its sub-modules.
      • Note that code and functional coverage goals are TBD due to pending evaluation of where / how to source a USB20 UVM VIP.
      • The decision is trending towards hooking up a cocotb (Python) based open source USB20 compliance test suite with this UVM environment.
  • FPV
    • Verify TileLink device protocol compliance with an SVA based testbench.

Current status

Design features

For detailed information on USBDEV design features, please see the USBDEV HWIP technical specification.

Testbench architecture

USBDEV testbench has been constructed based on the CIP testbench architecture.

Top level testbench

Top level testbench is located at hw/ip/usbdev/dv/tb/tb.sv. It instantiates the USBDEV DUT module hw/ip/usbdev/rtl/usbdev.sv. In addition, it instantiates the following interfaces, connects them to the DUT and sets their handle into uvm_config_db:

Common DV utility components

The following utilities provide generic helper tasks and functions to perform activities that are common across the project:

Compile-time configurations

None for now.

Global types & methods

All common types and methods defined at the package level can be found in usbdev_env_pkg. Some of them in use are:

[list a few parameters, types & methods; no need to mention all]

TL_agent

USBDEV testbench instantiates (already handled in CIP base env) tl_agent which provides the ability to drive and independently monitor random traffic via TL host interface into USBDEV device.

USB20 Agent

The usb20_agent is currently a skeleton implementation. It does not offer any functionality yet.

UVM RAL Model

The USBDEV RAL model is created with the ralgen FuseSoC generator script automatically when the simulation is at the build stage.

It can be created manually by invoking regtool:

Reference models

There are no reference models in use currently.

Stimulus strategy

Test sequences

All test sequences reside in hw/ip/usbdev/dv/env/seq_lib. The usbdev_base_vseq virtual sequence is extended from cip_base_vseq and serves as a starting point. All test sequences are extended from usbdev_base_vseq. It provides commonly used handles, variables, functions and tasks that the test sequences can simple use / call. Some of the most commonly used tasks / functions are as follows:

  • usbdev_init(): Do basic USB device initialization.

Functional coverage

To ensure high quality constrained random stimulus, it is necessary to develop a functional coverage model. The following covergroups have been developed to prove that the test intent has been adequately met:

  • TBD

Self-checking strategy

Scoreboard

The usbdev_scoreboard is primarily used for end to end checking. It creates the following analysis ports to retrieve the data monitored by corresponding interface agents:

  • TBD

Assertions

  • TLUL assertions: The tb/usbdev_bind.sv binds the tlul_assert assertions to the IP to ensure TileLink interface protocol compliance.
  • Unknown checks on DUT outputs: The RTL has assertions to ensure all outputs are initialized to known values after coming out of reset.
  • TBD

Building and running tests

We are using our in-house developed regression tool for building and running our tests and regressions. Please take a look at the link for detailed information on the usage, capabilities, features and known issues. Here's how to run a smoke test:

$ $REPO_TOP/util/dvsim/dvsim.py $REPO_TOP/hw/ip/usbdev/dv/usbdev_sim_cfg.hjson -i usbdev_smoke

Testplan

Testplan