# PINMUX DV document

## Goals
* **DV**:
  * TODO: Add a UVM testbench to reuse auto-generated common tests for TLUL and alerts.

* **FPV**:
  * Verify all the PINMUX outputs by writing assumptions and assertions with a FPV based testbench
  * Verify TileLink device protocol compliance with a FPV based testbench

## Current status
* [Design & verification stage](../../../../README.md)
  * [HW development stages](../../../../../doc/project_governance/development_stages.md)
* [FPV dashboard](https://reports.opentitan.org/hw/top_earlgrey/formal/summary.html)

## Design features
For detailed information on PINMUX design features, please see the
[PINMUX design specification](../../README.md).

## Testbench architecture
PINMUX FPV testbench has been constructed based on the [formal architecture](../../../../formal/README.md).

### Block diagram
![Block diagram](fpv.svg)

#### TLUL assertions
* The `../fpv/tb/pinmux_bind.sv` binds the `tlul_assert` [assertions](../../../tlul/doc/TlulProtocolChecker.md) with pinmux to ensure TileLink interface protocol compliance.
* The `../fpv/tb/pinmux_bind.sv` also binds the `pinmux_csr_assert_fpv` to assert the TileLink writes and reads correctly.

#### PINMUX assertions
* The `../fpv/tb/pinmux_bind_fpv.sv` binds module `pinmux_assert_fpv` with the pinmux RTL.
The assertion file ensures all pinmux's outputs are verified based on the [testplan](#testplan).

In the pinmux design, it includes usbdev logic because it operates on an always-on domain.
Pinmux FPV assertions will only cover the connectivities between usbdev IOs and pinmux IOs.
All functional checks will be implemented in the usbdev testbench.

##### Symbolic variables
Due to the large number of peripheral, muxed, dedicated IOs, and wakeup causes, symbolic variables are used to reduce the number of repeated assertions code.
In the pinmux_assert_fpv module, we declared four symbolic variables (`mio_sel_i`, `periph_sel_i`, `dio_sel_i`, `wkup_sel_i`) to represent the index for muxed IOs, peripheral IOs, dedicated IOs, and wakeup causes.
Detailed explanation is listed in the [Symbolic Variables](../../../../formal/README.md#symbolic-variables) section.

## Testplan
[Testplan](../../data/pinmux_fpv_testplan.hjson)