A tiny Open POWER ISA softcore written in VHDL 2008
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Benjamin Herrenschmidt 8bb3c8f8b6 soc: Add DRAM address decoding
Still not attached to any board

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
4 years ago
constraints Initial support for ghdl synthesis 5 years ago
fpga soc: Add DRAM address decoding 4 years ago
hello_world Update hello_world for 100Mhz clock 4 years ago
litedram litedram: Add basic support for LiteX LiteDRAM 4 years ago
media Add title image 5 years ago
micropython Update micropython 5 years ago
openocd Initial support for ghdl synthesis 5 years ago
rust_lib_demo Merge remote-tracking branch 'remotes/origin/master' 4 years ago
scripts litedram: Add basic support for LiteX LiteDRAM 4 years ago
sim-unisim Add a debug (DMI) bus and a JTAG interface to it on Xilinx FPGAs 5 years ago
tests Merge remote-tracking branch 'remotes/origin/master' 4 years ago
.gitignore Add VHDL TAGS 4 years ago
.travis.yml Allow a full make check on Travis 5 years ago
LICENSE Initial import of microwatt 5 years ago
Makefile litedram: Add basic support for LiteX LiteDRAM 4 years ago
Makefile.synth make the sources volume mount SELinux friendly 5 years ago
README.md Change the default cross compiler prefix to powerpc64le-linux-gnu- 4 years ago
cache_ram.vhdl dcache: Introduce an extra cycle latency to make timing 5 years ago
common.vhdl Merge remote-tracking branch 'remotes/origin/master' 4 years ago
control.vhdl core: Improve core reset 4 years ago
core.vhdl core: Add alternate reset address 4 years ago
core_debug.vhdl fetch/icache: Fit icache in BRAM 5 years ago
core_tb.vhdl soc: Add DRAM address decoding 4 years ago
countzero.vhdl countzero: Add a register to help make timing 5 years ago
countzero_tb.vhdl countzero: Add a register to help make timing 5 years ago
cr_file.vhdl Dump CTR, LR and CR on sim termination, and update our tests 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 dcache: Don't assert on dcbz cache hit 4 years ago
dcache_tb.vhdl loadstore1: Move logic from dcache to loadstore1 4 years ago
decode1.vhdl dcache: Implement the dcbz instruction 4 years ago
decode2.vhdl Plumb insn_type through to loadstore1 4 years ago
decode_types.vhdl Remove sim_config instruction 4 years ago
divider.vhdl execute1: Remember dest GPR, RC, OE, XER for slow operations 5 years ago
divider_tb.vhdl execute1: Remember dest GPR, RC, OE, XER for slow operations 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 execute1: Fix interrupt delivery during slow instructions 4 years ago
fetch1.vhdl core: Add alternate reset address 4 years ago
fetch2.vhdl core: Improve core reset 4 years ago
glibc_random.vhdl Reformat glibc_random 5 years ago
glibc_random_helpers.vhdl Reformat glibc_random 5 years ago
gpr_hazard.vhdl execute: Implement bypass from output of execute1 to input 5 years ago
helpers.vhdl execute: Copy XER[SO] to CR for cmp[i] and cmpl[i] instructions 5 years ago
icache.vhdl core: Improve core reset 4 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 Implement CRNOR and friends 5 years ago
loadstore1.vhdl dcache: Implement the dcbz instruction 4 years ago
logical.vhdl execute: Move popcnt and prty instructions into the logical unit 5 years ago
microwatt.core litedram: Add basic support for LiteX LiteDRAM 4 years ago
multiply.vhdl execute1: Remember dest GPR, RC, OE, XER for slow operations 5 years ago
multiply_tb.vhdl execute1: Remember dest GPR, RC, OE, XER for slow operations 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 Fix ghdlsynth issue 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 Consolidate VHPI code 5 years ago
sim_console.vhdl Reformat sim_console 5 years ago
sim_console_c.c Consolidate VHPI code 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 Consolidate VHPI code 5 years ago
sim_uart.vhdl Wire up sim uart TX interrupt 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 soc: Add DRAM address decoding 4 years ago
utils.vhdl Add log2ceil and use it in bram code 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 Add log2ceil and use it in bram code 5 years ago
wishbone_debug_master.vhdl wishbone_debug_master: Fix address auto-increment for memory writes 4 years ago
wishbone_types.vhdl wb_arbiter: Make arbiter size parametric 5 years ago
writeback.vhdl execute1: Simplify the interrupt logic a little 4 years ago
xics.vhdl XICS interrupt controller 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 images. Read through the Makefile for details.

  • 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

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)