[device] CW340 support

[nasahlpa]

This PR adds experimental CW340 support with a minimal running capture script.

[Blebowski]

Hi,
may I mask what is the status and plans here ? Is CW340 supposed to replace the CW310 for the purposes
of OT SCA ?

I see that the main board being used is CW310 currently. However, this-one features 7-series Kintex,
an older device that will eventually go out of support by Xilinx. The CW340 has Ultrascale which is newer
FPGA family with better clocking architecture (AFAICT better suited for ASIC emulation purposes).

Further, the NewAE web-page claims that CW340:

The CW340 is designed specifically for working with the OpenTitan design, either in FPGA emulation or with a production silicon device.

[nasahlpa]

Hi @Blebowski,

Thanks for your interest in ot-sca!

Currently, we are not planning to support CW340 in ot-sca. The reason is that capturing power traces on CW340 is much more challenging (i.e. more noise) due to the larger FPGA and the larger design. Hence, when capturing traces, we use the smaller OpenTitan design for CW310 and even remove some IPs that we are not measuring to minimize the noise.

However, adding support for CW340 by yourself should be quite straightforward - this draft PR should give you an idea how this could work.

[Blebowski]

Thanks @nasahlpa.

My thinking was precisely opposite. Since ultra-scale has better clocking, it would allow to emulate
e.g. per-IP clock gate enable as on the ASIC, and therefore not to cause noise from other IPs.

But I guess that Open Titan does not have per-peripheral manual gating(that needs to be functionally enabled
for peripheral to work) and relies only on inserted clock gates ?

[Blebowski]

So it is good to have the information instead of going completely wrong direction :)