I2C DV document

Goals

• DV
  • Verify all I2C 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
• FPV
  • Verify TileLink device protocol compliance with an SVA based testbench

Current status

• Design & verification stage
  • HW development stages
• Simulation results

Design features

For detailed information on I2C design features, please see the I2C design specification.

Testbench architecture

I2C testbench has been constructed based on the CIP testbench architecture.

Block diagram

Top level testbench

Top level testbench is located at hw/ip/i2c/dv/tb/tb.sv. It instantiates the I2C DUT module hw/ip/i2c/rtl/i2c.sv. In addition, it instantiates the following interfaces, connects them to the DUT and sets their handle into uvm_config_db:

• Clock and reset interface
• TileLink host interface
• I2C IOs
• Interrupts (pins_if)

Common DV utility components

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

• common_ifs
• dv_utils_pkg
• csr_utils_pkg

Global types & methods

All common types and methods defined at the package level can be found in i2c_env_pkg. Some of them are imported from i2c_reg_pkg.

TL_agent

I2C 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 I2C device.

I2C agent

I2C agent is configured to work in device mode and implemented as reactive agent.

UVM RAL Model

The I2C 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.

Stimulus strategy

Test sequences

All test sequences reside in hw/ip/i2c/dv/env/seq_lib. The i2c_base_vseq virtual sequence is extended from cip_base_vseq and serves as a starting point. All test sequences are extended from i2c_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:

• i2c_init: Setup the control register, identifier and clear the FIFOs.
• wait_{host|target}_for_idle.

Another test sequence used as a base for other sequences is i2c_rx_tx_vseq. This sequence is useful for tests that want to generate, receive or transmit packets.

Functional coverage

To ensure high quality constrained random stimulus, it is necessary to develop a functional coverage model. Please see the testplan for details of the covergroups.

Self-checking strategy

Scoreboard

The i2c_scoreboard is primarily used for end to end checking. It has a TL-UL interface to monitor interactions with the registers. It also creates the following queues to monitor I2C packets:

• rd_item_fifo: for read items.
• wr_item_fifo: for write items.

Assertions

• TL-UL assertions: The dv/sva/i2c_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.

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/i2c/dv/i2c_sim_cfg.hjson -i i2c_host_smoke

Testplan

Testplan