# NL.net proposal
+* NLNet Project Page <https://nlnet.nl/project/WishboneStreaming/>
+* 2019-10-043
+* Top Level bugreport <http://bugs.libre-riscv.org/show_bug.cgi?id=175>
+
## Project name
The Libre RISC-V SoC, Wishbone Streaming Proposal
## Abstract: Can you explain the whole project and its expected outcome(s).
-TODO
+In projects such as the Libre RISC-V SoC, commercial grade System-on-Chip
+(SoC) bus infrastructure is needed. Nowadays this often means AMBA AXI4,
+AXI4-lite or AXI4-Stream, all published by ARM Limited. The AXI family is
+"royality-free" and it is not only patented but its patent holder has
+begun denying licenses due to the US Trade War.
+
+The main alternative with large adoption is Wishbone, which is an Open
+Standard in contrast to AXI. However Wishbone does not have a "streaming"
+capability, which is typically needed for high-throughput data pathes and
+interfaces, e.g. for video applications and High-Performance Computing
+(HPC).
+
+Therefore this project will write up an enhancement to the Wishbone B4 SoC
+Bus, provide Reference Implementations and Bus Function Models (BFM) which
+easily allows unit tests for all Wishbone BFM users. For demonstration
+we like to implement an example peripheral (here, an audio interface, for
+the Libre RISC-V SoC) also. This demonstrations proves our concept also.
+
+A secondary objective will be to seek out Reference Implementations for
+Wishbone Master and Slave, provide formal correctness proofs, and add
+additional example peripherals - non-streaming ones - as resources permit.
# Have you been involved with projects or organisations relevant to this project before? And if so, can you tell us a bit about your contributions?
Luke Leighton is an ethical technology specialist who has a consistent
24-year track record of developing code in a real-time transparent
-(fully libre) fashion, and in managing Software Libre teams. He is the
+(fully libre) fashion, and in managing Software Libre teams. He is the
lead developer on the Libre RISC-V SoC.
-TODO
+Hagen Sankowski is a Senior ASIC Design Engineer, with 20-year Experiences
+thru the whole Design Flow, from Digital Entry (Verilog HDL, VHDL) to
+DSM Backend and back. He has FPGA knowledge for Xilinx, Altera, Lattice
+and MicroSemi. Inventor and Patentee for a FPGA structure. Open Source
+Evangelist, member of the LibreSilicon project Team also.
# Requested Amount
# Explain what the requested budget will be used for?
Improve the Wishbone B4 Specification to add streaming capability,
-similar to AXI4 Streams
+comparable to AXI4-Stream, and feed the improvements back into the
+current stewardship for next Wishbone release.
+
+Design Reference Implementations in nmigen and (System-)Verilog, Bus
+Function Models and other functionality in SystemVerilog for verification
+with full unit tests aiming best code coverage.
+
+Use some of the Libre RISC-V SoC peripherals as a test platform
+and demonstrator (I2S Audio Streaming) for the proposed standard
+modifications.
+
+Traveling expenses for presenting the Wishbone improvements to the RISC-V
+community once at the annual ORConf in 2020.
+
+As a secondary objective: seek out existing (non-streaming) Wishbone
+Master and Slave Bus implementations (or implement them if necessary),
+provide formal proof unit tests of their correctness, and add additional
+example peripherals.
# Does the project have other funding sources, both past and present?
-no.
+The concept of extending Wishbone to have streaming capability is entirely
+new: it has no source of funding.
+
+The Libre RISC-V SoC has funding from NLNet under a 2018 Grant: it was
+intending to use AXI4 prior to the U.S. Trade War.
# Compare your own project with existing or historical efforts.
-AXI4 but it is proprietary and patented.
+AXI4 has streaming (as AXI4-Stream) but it is proprietary and patented.
-## What are significant technical challenges you expect to solve during the project, if any?
+TileLink is an alternative protocol (with roots in the RISC-V academic
+community) but it is relatively new, quite complex, and does not have
+the same adoption as Wishbone.
+
+There do exist a number of pre-existing Wishbone Bus Master and
+Slave implementations: Wishbone has been around for a significantly
+long time and has been the de-facto choice in the Libre/Open Hardware
+community. Formal correctness proofs for Wishbone have been written by
+Dan Gisselquist in SystemVerilog, but none are written in nmigen.
-TODO
+## What are significant technical challenges you expect to solve during the project, if any?
-## Describe the ecosystem of the project, and how you will engage with relevant actors and promote the outcomes?
+This is a straightforward project. However the timing issues involved
+with Bus Negotiation can be awkward to get right and may need formal
+proofs to properly verify. Dan Gisselquist's work in his area shows
+how it can be done.
-TODO
+## Describe the ecosystem of the project, and how you will engage with relevant actors and promote the outcomes
As mentioned in the 2018 submission, the Libre RISC-V
SoC has a full set of resources for Libre Project Management and development:
* <http://libre-riscv.org/3d_gpu/>
* <https://nlnet.nl/project/Libre-RISCV/>
+* <https://cdn.opencores.org/downloads/wbspec_b4.pdf>
+* <https://zipcpu.com/zipcpu/2017/11/07/wb-formal.html>
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