microwatt

A tiny Open POWER ISA softcore written in VHDL 2008

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Paul Mackerras 23ade0b1c3 decode2: Minor cleanup Remove unused variable is_reg in decode_input_reg_a. Signed-off-by: Paul Mackerras <paulus@ozlabs.org>		5 years ago
fpga	ram: Rework main RAM interface	5 years ago
hello_world	…
media	Add title image	5 years ago
scripts	ram: Rework main RAM interface	5 years ago
sim-unisim	Add a debug (DMI) bus and a JTAG interface to it on Xilinx FPGAs	5 years ago
tests	…
.gitignore	Update gitignore for new test bench build files	5 years ago
.travis.yml	Allow a full make check on Travis	5 years ago
LICENSE	…
Makefile	sprs: Store common SPRs in register file	5 years ago
README.md	ram: Rework main RAM interface	5 years ago
cache_ram.vhdl	dcache: Introduce an extra cycle latency to make timing	5 years ago
common.vhdl	sprs: Store common SPRs in register file	5 years ago
control.vhdl	sprs: Store common SPRs in register file	5 years ago
core.vhdl	sprs: Store common SPRs in register file	5 years ago
core_debug.vhdl	fetch/icache: Fit icache in BRAM	5 years ago
core_tb.vhdl	ram: Rework main RAM interface	5 years ago
countzero.vhdl	countzero: Reorganize to have fewer levels of logic and fewer LUTs	5 years ago
countzero_tb.vhdl	countzero: Add a testbench	5 years ago
cr_file.vhdl	Add basic XER support	5 years ago
cr_hazard.vhdl	sprs: Store common SPRs in register file	5 years ago
crhelpers.vhdl	crhelpers: Constraint "crnum" integer	5 years ago
dcache.vhdl	Add basic XER support	5 years ago
dcache_tb.vhdl	ram: Rework main RAM interface	5 years ago
decode1.vhdl	sprs: Store common SPRs in register file	5 years ago
decode2.vhdl	decode2: Minor cleanup	5 years ago
decode_types.vhdl	sprs: Store common SPRs in register file	5 years ago
divider.vhdl	divider: Fix overflow calculation	5 years ago
divider_tb.vhdl	writeback: Do data formatting and condition recording in writeback	5 years ago
dmi_dtm_dummy.vhdl	Fix build issue in dmi_dtm_dummy.vhdl	5 years ago
dmi_dtm_tb.vhdl	ram: Rework main RAM interface	5 years ago
dmi_dtm_xilinx.vhdl	Don't reset JTAG request register asynchronously	5 years ago
execute1.vhdl	sprs: Store common SPRs in register file	5 years ago
fetch1.vhdl	fetch/icache: Fit icache in BRAM	5 years ago
fetch2.vhdl	fetch2: Remove blank line	5 years ago
glibc_random.vhdl	Reformat glibc_random	5 years ago
glibc_random_helpers.vhdl	Reformat glibc_random	5 years ago
gpr_hazard.vhdl	sprs: Store common SPRs in register file	5 years ago
helpers.vhdl	execute: Copy XER[SO] to CR for cmp[i] and cmpl[i] instructions	5 years ago
icache.vhdl	Move log2/ispow2 to a utils package	5 years ago
icache_tb.vhdl	ram: Rework main RAM interface	5 years ago
icache_test.bin	icache_tb: Improve test and include test file	5 years ago
insn_helpers.vhdl	Add basic XER support	5 years ago
loadstore1.vhdl	Add basic XER support	5 years ago
logical.vhdl	Consolidate logical instructions	5 years ago
microwatt.core	ram: Rework main RAM interface	5 years ago
multiply.vhdl	Add basic XER support	5 years ago
multiply_tb.vhdl	writeback: Do data formatting and condition recording in writeback	5 years ago
plru.vhdl	plru: Improve sensitivity list	5 years ago
plru_tb.vhdl	plru: Add a simple PLRU module	5 years ago
ppc_fx_insns.vhdl	sprs: Store common SPRs in register file	5 years ago
register_file.vhdl	sprs: Store common SPRs in register file	5 years ago
rotator.vhdl	Add a rotate/mask/shift unit and use it in execute1	5 years ago
rotator_tb.vhdl	Add a rotate/mask/shift unit and use it in execute1	5 years ago
sim_bram.vhdl	ram: Rework main RAM interface	5 years ago
sim_bram_helpers.vhdl	ram: Rework main RAM interface	5 years ago
sim_bram_helpers_c.c	ram: Rework main RAM interface	5 years ago
sim_console.vhdl	Reformat sim_console	5 years ago
sim_console_c.c	Make sim poll non-blocking	5 years ago
sim_jtag.vhdl	Add jtag support in simulation via a socket	5 years ago
sim_jtag_socket.vhdl	Add jtag support in simulation via a socket	5 years ago
sim_jtag_socket_c.c	debug/sim: Make connect/disconnect messages quieter	5 years ago
sim_uart.vhdl	Share soc.vhdl between FPGA and sim	5 years ago
soc.vhdl	wb_arbiter: Make arbiter size parametric	5 years ago
utils.vhdl	Move log2/ispow2 to a utils package	5 years ago
wishbone_arbiter.vhdl	wb_arbiter: Early master selection	5 years ago
wishbone_bram_tb.bin	ram: Rework main RAM interface	5 years ago
wishbone_bram_tb.vhdl	ram: Rework main RAM interface	5 years ago
wishbone_bram_wrapper.vhdl	ram: Ack stores early	5 years ago
wishbone_debug_master.vhdl	wb_debug: Add wishbone pipelining support	5 years ago
wishbone_types.vhdl	wb_arbiter: Make arbiter size parametric	5 years ago
writeback.vhdl	sprs: Store common SPRs in register file	5 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 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

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)