FPGA Configuration Space Specification (also known as SDB)

This project is an effort to introduce a configuration space specification for internal FPGA buses (interconnects, crossbars). Our initial target is Wishbone, but the specification is generic. The output of this project is called SDB (Self Describing Bus) even if the project (thus the repository) is called fpga-config-space.

SDB allows to enumerate the cores that are live in the current fpga binary, either from the host computer or from the internal soft-core CPU in the FPGA itself. It is also used as a simple filesystem in our EEPROM devices,
so data can be easily accessed by both the host and the soft core that lives in the FPGA itself.

The current specification is already in use in some of our designs. And we have some sdb implementation guidelines

Specification

Version 1.1 of SDB the specification is available in PDF format, together with the header file.
It has been built from the repository of this project, so you can get the git tree instead and run Latex on it.

Interrupt support

We chose, for the time being, to not describe interrupts. After some drafts for one such description, Wesley Terpstra
explained why legacy interrupts should be avoided in a SoC design and MSI-like interrupts don't need an external description.
His complete reasoning is here: Interrupts

Code

The implementation as VHDL is part of the respective projects.

Code for the Linux kernel (both as a bus driver and a file system driver) is being written. Available code
is part of this repository, but it's still work in progress. Sdbfs is being used in our EEPROMs using
the user-space tools and library currently in the "sdbfs" subdir of the repository

Project Information

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