A tiny Open POWER ISA softcore written in VHDL 2008
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Anton Blanchard b29c58f3d1 dcache: Loads from non-cacheable PTEs load entire 64 bits
A non-cacheable load should only load the data requested and no more. We
do the right thing for real mode cache inhibited storage instructions,
but when loading through a non-cacheable PTE we load the entire 64 bits
regardless of the size.

Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
3 years ago
.github/workflows ci: Add verilator tests 3 years ago
constraints Initial support for ghdl synthesis 5 years ago
fpga Merge pull request #316 from antonblanchard/verilator-fix 3 years ago
hello_world Reduce hello_world footprint to fit in 8kB 4 years ago
include arty_a7: Add litesdcard interface 4 years ago
lib console: Add support for the 16550 UART 4 years ago
litedram litedram: Regenerate from upstream litex 3 years ago
liteeth liteeth: Regenerate from upstream litex 3 years ago
litesdcard litesdcard: Use vendor not board type 3 years ago
media Add title image 5 years ago
micropython tests: Add updated micropython build with 16550 support 4 years ago
openocd openocd: Fix verify command for v0.10 4 years ago
rust_lib_demo console: Cleanup console API 4 years ago
scripts makefile: Add some verilator micropython tests 3 years ago
sim-unisim Add a debug (DMI) bus and a JTAG interface to it on Xilinx FPGAs 5 years ago
tests tests/misc: Add a test for a load that hits two preceding stores 3 years ago
uart16550 Add uart16550 files from fusesoc 4 years ago
verilator verilator: Specify top level module 3 years ago
.gitignore Add yosys builds files to gitignore 4 years ago
LICENSE Initial import of microwatt 5 years ago
Makefile makefile: Check environment for MEMORY_SIZE/RAM_INIT_FILE 3 years ago
README.md Update documentation. (#280) 4 years ago
cache_ram.vhdl Reformat cache_ram 4 years ago
common.vhdl PMU: Add several more events 3 years ago
control.vhdl Reformat control 4 years ago
core.vhdl PMU: Add several more events 3 years ago
core_debug.vhdl Fix some whitespace issues 3 years ago
core_dram_tb.vhdl Reformat testbenches 4 years ago
core_flash_tb.vhdl Reformat testbenches 4 years ago
core_tb.vhdl Reformat testbenches 4 years ago
countzero.vhdl Reformat countzero 4 years ago
countzero_tb.vhdl Replaced VHDL assert and report with VUnit checking and logging 3 years ago
cr_file.vhdl Reformat cr_file 4 years ago
crhelpers.vhdl crhelpers: Constraint "crnum" integer 5 years ago
dcache.vhdl dcache: Loads from non-cacheable PTEs load entire 64 bits 3 years ago
dcache_tb.vhdl Reformat testbenches 4 years ago
decode1.vhdl decode1: Fix maddld and maddhdu to not set CR0 3 years ago
decode2.vhdl core: Allow multiple loadstore instructions to be in flight 4 years ago
decode_types.vhdl core: Crack update-form loads into two internal ops 4 years ago
divider.vhdl Reformat divider 4 years ago
divider_tb.vhdl Replaced VHDL assert and report with VUnit checking and logging 3 years ago
dmi_dtm_dummy.vhdl Fix build issue in dmi_dtm_dummy.vhdl 5 years ago
dmi_dtm_tb.vhdl Reformat testbenches 4 years ago
dmi_dtm_xilinx.vhdl Fix some whitespace issues 3 years ago
dram_tb.vhdl Reformat testbenches 4 years ago
execute1.vhdl core: Fix mcrxrx, addpcis and bpermd 3 years ago
fetch1.vhdl core: Move redirect and interrupt delivery logic to writeback 4 years ago
foreign_random.vhdl Make core testbenches recognized by VUnit 3 years ago
fpu.vhdl core: Send FPU interrupts to writeback rather than execute1 4 years ago
glibc_random.vhdl Reformat glibc_random 5 years ago
glibc_random_helpers.vhdl Reformat glibc_random 5 years ago
gpio.vhdl Add a GPIO controller and use it to drive the shield I/O pins on the Arty 4 years ago
helpers.vhdl core: Add support for single-precision FP loads and stores 4 years ago
icache.vhdl PMU: Add several more events 3 years ago
icache_tb.vhdl Reformat testbenches 4 years ago
icache_test.bin icache_tb: Improve test and include test file 5 years ago
insn_helpers.vhdl core: Implement quadword loads and stores 4 years ago
loadstore1.vhdl PMU: Add several more events 3 years ago
logical.vhdl core: Fix mcrxrx, addpcis and bpermd 3 years ago
microwatt.core Merge pull request #315 from paulusmack/pmu 3 years ago
mmu.vhdl MMU: Implement a vestigial partition table 3 years ago
multiply.vhdl execute1: Take an extra cycle for OE=1 multiply instructions 4 years ago
multiply_tb.vhdl Replaced VHDL assert and report with VUnit checking and logging 3 years ago
nonrandom.vhdl Add random number generator and implement the darn instruction 4 years ago
plru.vhdl Reformat plru 4 years ago
plru_tb.vhdl Replaced VHDL assert and report with VUnit checking and logging 3 years ago
pmu.vhdl PMU: Add several more events 3 years ago
ppc_fx_insns.vhdl Fix some whitespace issues 3 years ago
random.vhdl Make core testbenches recognized by VUnit 3 years ago
register_file.vhdl Reformat register_file 4 years ago
rotator.vhdl Reformat rotator 4 years ago
rotator_tb.vhdl Replaced VHDL assert and report with VUnit checking and logging 3 years ago
run.py VUnit: style 3 years ago
sim_16550_uart.vhdl uart: Add a simulation model for the 16550 compatible UART 4 years ago
sim_bram.vhdl Rename 'do' signal to avoid verilator System Verilog warning 3 years ago
sim_bram_helpers.vhdl ram: Rework main RAM interface 5 years ago
sim_bram_helpers_c.c Consolidate VHPI code 5 years ago
sim_console.vhdl Reformat sim_console 5 years ago
sim_console_c.c sim_console: Fix polling to check for POLLIN 4 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 Consolidate VHPI code 5 years ago
sim_no_flash.vhdl spi: Add simulation support 4 years ago
sim_pp_uart.vhdl uart: Rename sim_uart.vhdl to sim_pp_uart.vhdl 4 years ago
sim_vhpi_c.c Consolidate VHPI code 5 years ago
sim_vhpi_c.h Consolidate VHPI code 5 years ago
soc.vhdl gpio: Add HAS_GPIO to avoid verilator build errors 3 years ago
spi_flash_ctrl.vhdl Reformat spi_flash_ctrl 4 years ago
spi_rxtx.vhdl Merge pull request #265 from antonblanchard/another-spi-rxtx-reset-issu 4 years ago
sync_fifo.vhdl litedram: Add an L2 cache with store queue 4 years ago
syscon.vhdl arty_a7: Add litesdcard interface 4 years ago
utils.vhdl litedram: Add support for booting without BRAM 4 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 Reformat testbenches 4 years ago
wishbone_bram_wrapper.vhdl Rename 'do' signal to avoid verilator System Verilog warning 3 years ago
wishbone_debug_master.vhdl Fix some whitespace issues 3 years ago
wishbone_types.vhdl arty_a7: Add litesdcard interface 4 years ago
writeback.vhdl PMU: Add several more events 3 years ago
xics.vhdl Fix some whitespace issues 3 years ago
xilinx-mult.vhdl execute1: Take an extra cycle for OE=1 multiply instructions 4 years ago

README.md

Microwatt

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
  • If this is your first time using fusesoc, initialize fusesoc. This is needed to be able to pull down fussoc library components referenced by microwatt. Run
fusesoc init
  • 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): You may wish to ensure you have installed Digilent Board files or appropriate files for your board first.
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)