Overview
--------

Source Release of J-Core J2 CPU and associated platform hardware.

This package generates the top level RTL from the pin list and a set
of RTL source repositories.

lib/
Contains the VHDL library package reposotories which the chip depends on.

components/
The logic block repositories that the chip is built from. These
include large components like the SH CPU, peripheral devices with
memory-mapped registers like UARTs, and low-level components like
clock generators.

targets/boards/
Board-specific files containing Makefiles, contraint files, design
descriptions and generated VHDL. The generated VHDL stitches together
the hand-written VHDL from the components directories to build the SoC
and connects the external inputs and output lines to pins.

targets/soc_gen/
Tool for generating top-level VHDL for boards from design descriptions.

tests/
Simulation test benches for blocks, sets of blocks, subsystems and
full chip. This top-level tests directory isn't used currently.
Instead different subrepos have their own tests directories. See the
Tests section below for how to run those.

tools/
RTL and SoC generation tools.


Tests
-----

Running "make check" builds and run some tests. Currently these tests
are gathered and run from various subrepos and there are no top-level
tests. Eventually the tests/ directory will contain integration tests
of multiple parts of the soc.

Here is some example output:

  Running all tests listed in TESTS.  If any tests fail, run the failing
  test program with runtests -o to see more details.

  components/cpu/tests/register_tap................ok
  components/cpu/tests/mult_tap....................ok
  components/cpu/tests/divider_tap.................ok
  components/cpu/tests/bshift_tap..................ok
  components/cpu/tests/arith_tap...................ok
  components/cpu/tests/logic_tap...................ok
  components/cpu/tests/manip_tap...................ok
  components/misc/tests/gpio_tap...................ok
  components/misc/tests/multi_master_bus_mux_tap...ok
  components/ring_bus/word_tap.....................ok
  components/ring_bus/node_tap.....................ok
  components/ring_bus/data_bus_adapter_tap.........ok
  components/ring_bus/rbus_data_master_tap.........ok

  All tests successful.
  Files=13,  Tests=392,  0.03 seconds (0.02 usr + 0.01 sys = 0.03 CPU)

Building
--------

The top-level Makefile has targets for each module/mother board
combination. To build a bitstream for the Jx board 1v1
board run

  soc_top$ make turtle_1v1

The output of the build is placed in a newly created directory under
output/. The name of the directory contains the current date and time.
A symbolic link named "last_output" directory that points to the new
output directory is also created.

For example, it might create a directory called

  soc_top/output/2019-02-15_21-44-19_turtle_1v1

and there will be a symbolic link pointing to the above directory called

  soc_top$ ls -l last_output
  lrwxrwxrwx 1 geoff geoff 42 Feb  15 21:44 last_output -> output/2019-02-15_21-44-19_turtle_1v1


Prerequisites
-------------

The bitstream build require Xilinx ISE tools be installed and
available on the PATH.

Boards with device trees embedded in the bootloader require the
utlitity 'dtc' is installed. dtc is distributed with the linux kernel
source. It is also available in distro package repos
(device-tree-compiler in Debian and Ubuntu).

Building the bootloader uses an cross compiler toolchain prefixed with
sh2-elf-. That can be changed by setting CROSS_COMPILE on the command
line.

soc_gen
-------

The Makefile targets like "turtle_1v0" come from directory names in targets/boards

  soc_top$ ls targets/boards/
  turtle_1v0 turtle_1v1 mimas_v2 ...

Each of these directories contains the board-specific files including
a Makefile, constraints file, generated VHDL files and a design.edn
file. The design.edn file is one of the inputs to the soc_gen tool
which generates the VHDL files. The file format edn is defined here
https://github.com/edn-format/edn, but there are no docs about writing
a design.edn file yet. Refer to the existing ones for examples.

To run soc_gen, and regenerated the VHDL files in one of the
targets/boards/turtle_1v1 directory run

  soc_top$ make turtle_1v1 TARGET=soc_gen

Run soc_gen against all boards by running

  soc_top$ make soc_gen

You can also pass a regular expression to select which boards you want
to run with the BOARDS parameter

  soc_top$ make soc_gen BOARDS="turtle"

However, to run above command you'll need to do one of two things:

1) Install a JDK and the tool leiningen (http://leiningen.org/).
leiningen exists in many linux distributions software repos, but is
often an old 1.x version. You will have better luck copying the lein
file from the webpage and putting it in your user's ~/bin directory
and ensuring that directory is in your PATH.

2) or get the soc_gen.jar file and place it in your soc_top directory.
With this file, you will only need a JRE installed. You likely already
have a JRE. Try running "java" to see you have java installed.

If you have the JDK and lein installed and want to create soc_gen.jar,
cd to the targets/soc_gen directory and run

  soc_top/targets/soc_gen$ ./create_jar.sh

and it will create soc_gen.jar in that directory. The soc_top Makefile
won't use the jar file unless it's placed in soc_top/.