microwatt

A tiny Open POWER ISA softcore written in VHDL 2008

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Paul Mackerras 1d09daae03 loadstore1: Complete mfspr/mtspr a cycle later This makes mfspr and mtspr complete (and mfspr write back) on the cycle after the instruction is received from execute1, rather than on the same cycle. This makes them match all other instructions that execute in one cycle. Because these instructions are marked as single-issue, there wasn't the possibility of having two instructions complete on the same cycle (which we can't cope with), but it is better to fix this. Signed-off-by: Paul Mackerras <paulus@ozlabs.org>		4 years ago
.github/workflows	…
constraints	…
fpga	…
hello_world	…
include	…
lib	…
litedram	…
media	…
micropython	…
openocd	…
rust_lib_demo	…
scripts	Add core logging	4 years ago
sim-unisim	…
tests	…
verilator	…
.gitignore	…
LICENSE	…
Makefile	core: Remove fetch2 pipeline stage	4 years ago
README.md	…
cache_ram.vhdl	…
common.vhdl	core: Use a busy signal rather than a stall	4 years ago
control.vhdl	core: Use a busy signal rather than a stall	4 years ago
core.vhdl	core: Use a busy signal rather than a stall	4 years ago
core_debug.vhdl	Add core logging	4 years ago
core_dram_tb.vhdl	…
core_flash_tb.vhdl	…
core_tb.vhdl	…
countzero.vhdl	…
countzero_tb.vhdl	…
cr_file.vhdl	Add core logging	4 years ago
cr_hazard.vhdl	core: Use a busy signal rather than a stall	4 years ago
crhelpers.vhdl	…
dcache.vhdl	Add core logging	4 years ago
dcache_tb.vhdl	…
decode1.vhdl	core: Remove fetch2 pipeline stage	4 years ago
decode2.vhdl	core: Use a busy signal rather than a stall	4 years ago
decode_types.vhdl	…
divider.vhdl	…
divider_tb.vhdl	…
dmi_dtm_dummy.vhdl	…
dmi_dtm_tb.vhdl	…
dmi_dtm_xilinx.vhdl	…
dram_tb.vhdl	…
execute1.vhdl	core: Use a busy signal rather than a stall	4 years ago
fetch1.vhdl	icache: Improve latencies when reloading cache lines	4 years ago
glibc_random.vhdl	…
glibc_random_helpers.vhdl	…
gpr_hazard.vhdl	core: Use a busy signal rather than a stall	4 years ago
helpers.vhdl	…
icache.vhdl	icache: Improve latencies when reloading cache lines	4 years ago
icache_tb.vhdl	core: Remove fetch2 pipeline stage	4 years ago
icache_test.bin	…
insn_helpers.vhdl	…
loadstore1.vhdl	loadstore1: Complete mfspr/mtspr a cycle later	4 years ago
logical.vhdl	…
microwatt.core	multiply: Use DSP48 slices for multiplication on Xilinx FPGAs	4 years ago
mmu.vhdl	…
multiply.vhdl	multiply: Move selection of result bits into execute1	4 years ago
multiply_tb.vhdl	multiply: Move selection of result bits into execute1	4 years ago
plru.vhdl	…
plru_tb.vhdl	…
ppc_fx_insns.vhdl	…
register_file.vhdl	Add core logging	4 years ago
rotator.vhdl	…
rotator_tb.vhdl	…
sim_bram.vhdl	…
sim_bram_helpers.vhdl	…
sim_bram_helpers_c.c	…
sim_console.vhdl	…
sim_console_c.c	…
sim_jtag.vhdl	…
sim_jtag_socket.vhdl	…
sim_jtag_socket_c.c	…
sim_no_flash.vhdl	…
sim_uart.vhdl	…
sim_vhpi_c.c	…
sim_vhpi_c.h	…
soc.vhdl	…
spi_flash_ctrl.vhdl	…
spi_rxtx.vhdl	…
sync_fifo.vhdl	…
syscon.vhdl	…
utils.vhdl	…
wishbone_arbiter.vhdl	…
wishbone_bram_tb.bin	…
wishbone_bram_tb.vhdl	…
wishbone_bram_wrapper.vhdl	…
wishbone_debug_master.vhdl	…
wishbone_types.vhdl	…
writeback.vhdl	core: Use a busy signal rather than a stall	4 years ago
xics.vhdl	…
xilinx-mult.vhdl	multiply: Use DSP48 slices for multiplication on Xilinx FPGAs	4 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. You may need to set the CROSS_COMPILE environment variable to the prefix used for your cross compilers. The default is powerpc64le-linux-gnu-.

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

A prebuilt micropython image is also available in the micropython/ directory.

Microwatt uses ghdl for simulation. Either install this from your distro or build it. Microwatt requires ghdl to be built with the LLVM or gcc backend, which not all distros do (Fedora does, Debian/Ubuntu appears not to). ghdl with the LLVM backend is likely easier to build.

If building ghdl from scratch is too much for you, the microwatt Makefile supports using Docker or Podman.
Next build microwatt:

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

To build using Docker:

make DOCKER=1

and to build using Podman:

make PODMAN=1

Link in the micropython image:

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

Or if you were using the pre-built image:

ln -s micropython/firmware.bin main_ram.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

Fedora users can get FuseSoC package via

sudo dnf copr enable sharkcz/danny
sudo dnf install 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=16384 --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)