From 190366e05e831d7f6cd595d49fe9e57f333e7288 Mon Sep 17 00:00:00 2001 From: Luke Kenneth Casson Leighton Date: Thu, 26 Sep 2019 05:32:15 +0100 Subject: [PATCH] update from hagen --- nlnet_2019_wishbone_streaming.mdwn | 73 +++++++++++++++++------------- 1 file changed, 42 insertions(+), 31 deletions(-) diff --git a/nlnet_2019_wishbone_streaming.mdwn b/nlnet_2019_wishbone_streaming.mdwn index 075c9be6c..706f2dc56 100644 --- a/nlnet_2019_wishbone_streaming.mdwn +++ b/nlnet_2019_wishbone_streaming.mdwn @@ -19,20 +19,23 @@ if you need any HTML to make your point please include this as attachment. ## Abstract: Can you explain the whole project and its expected outcome(s). -In projects such as the Libre RISCV SoC, commercial grade communications -bus infrastructure is needed. Ordinarily this would mean AXI4 however -it is not only patented but its patent holder (ARM) has begun denying -licenses due to the US trade war. - -The main alternative with large adoption is Wishbone. However Wishbone -does not have "streaming" capability (basically the ability to embed -"timecode" stamps into a data stream), which is typically needed for -audio and video streaming interfaces. - -Therefore this project will write up an enhancement to the Wishbone B4 -interface, provide Reference Implementations and unit tests, and also -implement an example peripheral, an audio interface, for the Libre RISC-V -SoC in order to prove the concept. +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 @@ -42,14 +45,14 @@ additional example peripherals - non-streaming ones - as resources permit. 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. -Hagen Sankowski is a Senior ASIC Design Engineer, with Experiences -thru the whole Design Flow, from Digital Entry (Verilog HDL, VHDL) -to DSM Backend and back. FPGA knowledge for Xilinx, Altera, Lattice -and MicroSemi. Inventor and Patentee for a FPGA structure. Open Source -Evangelist, always interested in challenging FPGA and migration projects. +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 @@ -58,12 +61,19 @@ EUR 50,000. # 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 verilog, with full unit tests. +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 -(I2S Audio Streaming) for the proposed standard modifications. +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), @@ -80,16 +90,17 @@ intending to use AXI4 prior to the U.S. Trade War. # Compare your own project with existing or historical efforts. -AXI4 has streaming but it is proprietary and patented. +AXI4 has streaming (as AXI4-Stream) but it is proprietary and patented. -TileLink is the alternative protocol but it is relatively new, quite -complex, and does not have the same adoption as Wishbone. +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 verilog, but none are written in nmigen. +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. ## What are significant technical challenges you expect to solve during the project, if any? -- 2.30.2