PWM DV document
- Verify all PWM IP features by running dynamic simulations with a SV/UVM based testbench
- Develop and run all tests based on the DV plan below towards closing code and functional coverage on the IP and all of its sub-modules
- Verify TileLink device protocol compliance with an SVA based testbench
For detailed information on PWM design features, please see the PWM HWIP technical specification.
PWM testbench has been constructed based on the CIP testbench architecture.
Top level testbench
Top level testbench is located at
hw/ip/pwm/dv/tb/tb.sv. It instantiates the PWM DUT module
In addition, it instantiates the following interfaces, connects them to the DUT and sets their handle into
Common DV utility components
The following utilities provide generic helper tasks and functions to perform activities that are common across the project:
Global types & methods
All common types and methods defined at the package level can be found in
pwm_env_pkg. Some of them in use are:
parameter uint NUM_PWM_CHANNELS = 6;
PWM 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 PWM device.
PWM agent is configured to work device mode.
The agent monitor captures pulses generated in channels then sends to the scoreboard for verification
Since the DUT does not require any response thus agent driver is fairly simple.
UVM RAL Model
The PWM RAL model is created with the
FuseSoC generator script automatically when the simulation is at the build stage.
It can be created manually by invoking
All test sequences reside in
pwm_base_vseq virtual sequence is extended from
cip_base_vseq and serves as a starting point.
All test sequences are extended from
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:
- task 1:
- task 2:
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:
pwm_scoreboard is primarily used for end to end checking.
It creates the following analysis ports to retrieve the data monitored by corresponding interface agents:
- analysis port1:
- analysis port2:
- TLUL assertions: The
tlul_assertassertions 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.
- assert prop 1:
- assert prop 2:
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/pwm/dv/pwm_sim_cfg.hjson -i pwm_smoke
Smoke test accessing a major datapath within the pwm
Verify the reset values as indicated in the RAL specification.
Verify accessibility of CSRs as indicated in the RAL specification.
Verify no aliasing within individual bits of a CSR.
Verify no aliasing within the CSR address space.
Verify random reset during CSR/memory access.
Checking ip operation at min/max bandwidth
Test the blinking mode of pwm
Test the heartbeat mode of pwm
TBD -Verify the function of clock-crossing domain for pwm
Combine above sequences in one test then randomly select for running
Verify common intr_test CSRs that allows SW to mock-inject interrupts.
The CSR test sequences will read and write accessible CSRs including the enable registers and their locked registers. The RAL model supports predicting the correct value of the locked registers based on their enable registers.
Access out of bounds address and verify correctness of response / behavior
Drive unsupported requests via TL interface and verify correctness of response / behavior. Below error cases are tested
Drive back-to-back requests without waiting for response to ensure there is one transaction outstanding within the TL device. Also, verify one outstanding when back- to-back accesses are made to the same address.
Access CSR with one or more bytes of data For read, expect to return all word value of the CSR For write, enabling bytes should cover all CSR valid fields