microwatt

A tiny Open POWER ISA softcore written in VHDL 2008

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Benjamin Herrenschmidt 1a63c39704 Make it possible to change wishbone address size All that needs to be changed now is the size in wishbone_types.vhdl and the address decoder in soc.vhdl Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>		6 years ago
fpga	Fix clk_gen_bypass	6 years ago
hello_world	Rebuild hello world assuming a 50MHz clock	6 years ago
media	Add title image	6 years ago
scripts	icache_tb: Improve test and include test file	6 years ago
sim-unisim	Add a debug (DMI) bus and a JTAG interface to it on Xilinx FPGAs	6 years ago
tests	Initial import of microwatt	6 years ago
.gitignore	Update gitignore for new test bench build files	6 years ago
.travis.yml	Allow a full make check on Travis	6 years ago
LICENSE	Initial import of microwatt	6 years ago
Makefile	dcache: Add testbench	6 years ago
README.md	Minor tweaks to README.md	6 years ago
cache_ram.vhdl	dcache: Introduce an extra cycle latency to make timing	6 years ago
common.vhdl	dcache: Add a dcache	6 years ago
control.vhdl	Add CR hazard detection	6 years ago
core.vhdl	insn: Simplistic implementation of icbi	6 years ago
core_debug.vhdl	fetch/icache: Fit icache in BRAM	6 years ago
core_tb.vhdl	Add core debug module	6 years ago
countzero.vhdl	countzero: Reorganize to have fewer levels of logic and fewer LUTs	6 years ago
countzero_tb.vhdl	countzero: Add a testbench	6 years ago
cr_file.vhdl	Reformat CR file	6 years ago
cr_hazard.vhdl	Add CR hazard detection	6 years ago
crhelpers.vhdl	crhelpers: Constraint "crnum" integer	6 years ago
dcache.vhdl	Make it possible to change wishbone address size	6 years ago
dcache_tb.vhdl	dcache: Add testbench	6 years ago
decode1.vhdl	insn: Simplistic implementation of icbi	6 years ago
decode2.vhdl	Do sign-extension instructions in writeback instead of execute1	6 years ago
decode_types.vhdl	Merge pull request #105 from paulusmack/writeback	6 years ago
divider.vhdl	writeback: Do data formatting and condition recording in writeback	6 years ago
divider_tb.vhdl	writeback: Do data formatting and condition recording in writeback	6 years ago
dmi_dtm_dummy.vhdl	Fix build issue in dmi_dtm_dummy.vhdl	6 years ago
dmi_dtm_tb.vhdl	Wishbone debug module	6 years ago
dmi_dtm_xilinx.vhdl	Don't reset JTAG request register asynchronously	6 years ago
execute1.vhdl	insn: Simplistic implementation of icbi	6 years ago
fetch1.vhdl	fetch/icache: Fit icache in BRAM	6 years ago
fetch2.vhdl	fetch2: Remove blank line	6 years ago
glibc_random.vhdl	Reformat glibc_random	6 years ago
glibc_random_helpers.vhdl	Reformat glibc_random	6 years ago
gpr_hazard.vhdl	Add GPR hazard detection	6 years ago
helpers.vhdl	Reformat helpers	6 years ago
icache.vhdl	Make it possible to change wishbone address size	6 years ago
icache_tb.vhdl	icache_tb: Improve test and include test file	6 years ago
icache_test.bin	icache_tb: Improve test and include test file	6 years ago
insn_helpers.vhdl	Add MCRF instruction	6 years ago
loadstore1.vhdl	dcache: Add a dcache	6 years ago
logical.vhdl	Consolidate logical instructions	6 years ago
microwatt.core	dcache: Add a dcache	6 years ago
multiply.vhdl	writeback: Do data formatting and condition recording in writeback	6 years ago
multiply_tb.vhdl	writeback: Do data formatting and condition recording in writeback	6 years ago
plru.vhdl	plru: Improve sensitivity list	6 years ago
plru_tb.vhdl	plru: Add a simple PLRU module	6 years ago
ppc_fx_insns.vhdl	Implement absolute branches	6 years ago
register_file.vhdl	Fix register file size (there are 32 gprs).	6 years ago
rotator.vhdl	Add a rotate/mask/shift unit and use it in execute1	6 years ago
rotator_tb.vhdl	Add a rotate/mask/shift unit and use it in execute1	6 years ago
sim_console.vhdl	Reformat sim_console	6 years ago
sim_console_c.c	Make sim poll non-blocking	6 years ago
sim_jtag.vhdl	Add jtag support in simulation via a socket	6 years ago
sim_jtag_socket.vhdl	Add jtag support in simulation via a socket	6 years ago
sim_jtag_socket_c.c	debug/sim: Make connect/disconnect messages quieter	6 years ago
sim_uart.vhdl	Share soc.vhdl between FPGA and sim	6 years ago
simple_ram_behavioural.vhdl	Make it possible to change wishbone address size	6 years ago
simple_ram_behavioural_helpers.vhdl	Reformat simple_ram_behavioural	6 years ago
simple_ram_behavioural_helpers_c.c	Silence some loadstore related debug	6 years ago
simple_ram_behavioural_tb.bin	Initial import of microwatt	6 years ago
simple_ram_behavioural_tb.vhdl	Make it possible to change wishbone address size	6 years ago
soc.vhdl	Tighten UART address	6 years ago
wishbone_arbiter.vhdl	Use a 3 way WB arbiter and cleanup fpga toplevel	6 years ago
wishbone_debug_master.vhdl	Make it possible to change wishbone address size	6 years ago
wishbone_types.vhdl	dcache: Add a dcache	6 years ago
writeback.vhdl	dcache: Add a dcache	6 years ago

README.md

Microwatt

A tiny Open POWER ISA softcore written in VHDL 2008. It aims to be simple and easy to understand.

Simulation using ghdl

MicroPython running on Microwatt

You can try out Microwatt/Micropython without hardware by using the ghdl simulator. If you want to build directly for a hardware target board, see below.

Build micropython. If you aren't building on a ppc64le box you will need a cross compiler. If it isn't available on your distro grab the powerpc64le-power8 toolchain from https://toolchains.bootlin.com

git clone https://github.com/mikey/micropython
cd micropython
git checkout powerpc
cd ports/powerpc
make -j$(nproc)
cd ../../../

Microwatt uses ghdl for simulation. Either install this from your distro or build it. Next build microwatt:

git clone https://github.com/antonblanchard/microwatt
cd microwatt
make

Link in the micropython image:

ln -s ../micropython/ports/powerpc/build/firmware.bin simple_ram_behavioural.bin

Now run microwatt, sending debug output to /dev/null:

./core_tb > /dev/null

Synthesis on Xilinx FPGAs using Vivado

Install Vivado (I'm using the free 2019.1 webpack edition).
Setup Vivado paths:

source /opt/Xilinx/Vivado/2019.1/settings64.sh

Install FuseSoC:

pip3 install --user -U fusesoc

Create a working directory and point FuseSoC at microwatt:

mkdir microwatt-fusesoc
cd microwatt-fusesoc
fusesoc library add microwatt /path/to/microwatt/

Build using FuseSoC. For hello world (Replace nexys_video with your FPGA board such as --target=arty_a7-100):

fusesoc run --target=nexys_video microwatt --memory_size=8192 --ram_init_file=/path/to/microwatt/fpga/hello_world.hex

You should then be able to see output via the serial port of the board (/dev/ttyUSB1, 115200 for example assuming standard clock speeds). There is a know bug where initial output may not be sent - try the reset (not programming button on your board if you don't see anything.

To build micropython (currently requires 1MB of BRAM eg an Artix-7 A200):

fusesoc run --target=nexys_video microwatt

Testing

A simple test suite containing random execution test cases and a couple of micropython test cases can be run with:

make -j$(nproc) check

Issues

This is functional, but very simple. We still have quite a lot to do:

There are a few instructions still to be implemented
Need to add caches and bypassing (in progress)
Need to add supervisor state (in progress)