[Arm-netbook] libre 64-bit risc-v SoC

[Allan Mwenda]

Yes. Do it. DO IT. 

On 27 April 2017 14:21:08 GMT+03:00, Luke Kenneth Casson Leighton <lkcl at lkcl.net> wrote:
>ok so it would seem that the huge amount of work going into RISC-V
>means that it's on track to becoming a steamroller that will squash
>proprietary SoCs, so i'm quite happy to make sure that it's
>not-so-subtly nudged in the right direction.
>
>i've started a page where i am keeping notes:
>http://rhombus-tech.net/riscv/libre_riscv/ and the general goal is to
>create a desirable mass-volume low-cost SoC, meaning that it will need
>to at least do 1080p60 video decode and have 3D graphics capability.
>oh... and be entirely libre.
>
>the plan is:
>
>* to create an absolute basic SoC, starting from lowRISC (64-bit),
>ORGFX (3D graphics) and MIAOW (OpenCL engine), in at least 90nm as a
>low-cost proof-of-concept where mistakes can be iterated through
>* provide the end-result to software developers so that they can have
>actual real silicon to work with
>* begin a first crowd-funding phase to create a 28nm (or better)
>multi-core SMP SoC
>
>for this first phase the interfaces that i've tracked down so far are
>almost entirely from opencores.org, meaning that there really should
>be absolutely no need to license any costly hard macros.  that
>*includes* a DDR3 controller (but does not include a DDR3 PHY, which
>will need to be designed):
>
>* DDR3 controller (not including PHY)
>* lowRISC contains "minion cores" so can be soft-programmed to do any
>GPIO
>* boot and debug through ZipCPU's UART (use an existing EC's on-board
>FLASH)
>* OpenCores VGA controller (actually it's an LCD RGB/TTL controller)
>* OpenCores ULPI USB 2.0 controller
>* OpenCores USB-OTG 1.1 PHY
>
>note that there are NO ANALOG INTERFACES in that.  this is *really*
>important to avoid, because mixed analog and digital is incredibly
>hard to get right.  also note that things like HDMI, SATA, and even
>ethernet are quite deliberately NOT on the list.  Ethernet RMII (which
>is digital) could be implemented in software using a minion core.  the
>advantage of using the opencores VGA (actually LCD) controller is: i
>already have the full source for a *complete* linux driver.
>
>I2C, SPI, SD/MMC, UART, EINT and GPIO - all of these can be
>software-programmed as bit-banging in the minion cores.
>
>these interfaces, amazingly, are enough to do an SoC that, if put into
>40nm, would easily compete with some of TI's offerings, as well as the
>Allwinner R8 (aka A13).
>
>i've also managed to get alliance and coriolis2 compiled on
>debian/testing (took a while) so it *might* not be necessary even to
>pay for the ASIC design tooling (the cost of which is insane).
>coriolis2 includes a reasonable auto-router.  i still have yet to go
>through the tutorials to see how it works.  for design rules: 90nm
>design rules (stacks etc.) are actually publicly available, which
>would potentially mean that a clock rate of at least 300mhz would be
>achievable: interestingly 800mhz DDR3 RAM from 2012 used 90nm
>geometry.  65 down to 40nm would be much more preferable but may be
>hard to get.
>
>graphics: i'm going through the list of people who have done GPUs (or
>parts of one).  MIAOW, Nyuzi, ORGFX.  the gplgpu isn't gpl. it's been
>modified to "the text of the GPL license plus an additional clause
>which is that if you want to use this for commercial purposes then...
>you can't". which is *NOT* a GPL license, it's a proprietary
>commercial license!
>
>MIAOW is just an OpenCL engine but a stonking good one that's
>compatible with AMD's software.  nyuzi is an experimental GPU where i
>hope its developer believes in its potential.  ORGFX i am currently
>evaluating but it looks pretty damn good, and i think it is slightly
>underestimated.  i could really use some help evaluating it properly.
>my feeling is that a combination of MIAOW to handle shading and ORGFX
>for the rendering would be a really powerful combination.
>
>so.
>
>it's basically doable.  comments and ideas welcome, please do edit the
>page to keep track of notes http://rhombus-tech.net/riscv/libre_riscv/
>
>---
>crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68
>
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