Guide to adding a new device to an existing family
==================================================

This documents how to add support for a new device. The running example
is the addition of the xc7a100t device to the Artix-7 family.

Adding a new device to an existing family is much simpler than adding a
new family, since the building blocks (tiles) are already known. There
are just more or fewer of them, arranged differently. No new fuzzers are
needed. You just need to rerun some fuzzers for the new device to
understand how the tiles are connected to each other and to IOs.

Note: Since this guide was written, the xc7a100t has become the primary
device in the database, not a secondary device as it was when it was
originally added. Therefore the files currently in the repo don’t match
what is described here. But if you look at the original PRs, they match
what is described in the examples here.

The main PR from the example is
`#1313 <https://github.com/SymbiFlow/prjxray/pull/1313>`__. Followup
fixes for problems revealed during testing are
`#1334 <https://github.com/SymbiFlow/prjxray/pull/1334>`__ and
`#1336 <https://github.com/SymbiFlow/prjxray/pull/1336>`__.

Step 0
~~~~~~

Fork a copy of https://github.com/SymbiFlow/prjxray on GitHub (go to the
page, click “Fork” button, select your own workspace).

Clone your fork, and make a new branch, with a name related to the new
device/package:

::

   git clone git@github.com:<yourUserID>/prjxray.git
   cd prjxray
   git checkout -b <new_branch_name>

Step 1
~~~~~~

Follow the Project X-Ray developer setup instructions in the
`documentation <https://symbiflow.readthedocs.io/en/latest/prjxray/docs/db_dev_process/readme.html>`__,
up through Step 7 and choose Option 1 (invoke the
``./download-latest-db.sh`` script). This script will clone the official
prjxray-db database under ``database/``. The following steps will make
changes under this directory. You may want to put these changes on your
own fork of ``prjxray-db`` for testing. This is explained at the end,
under “Database Updates”.

Step 2
~~~~~~

Add a new settings file. Usually you will start with an existing
settings file and modify it. Assuming you’re in prjxray/,

::

   cp settings/<baseline_device>.sh settings/<new_device>.sh
   git add settings/<new_device>.sh

Example:

::

   cp settings/artix7_200t.sh settings/artix7_100t.sh
   git add settings/artix7_100t.sh

Update the following values in the new settings file:

-  ``XRAY_PART`` –
   Important: choose a package that is fully bonded (typically the one with
   the largest number of pins). If the part that you’re actually interested
   in is different (with fewer bonded pins), it will be handled later. In
   the running example, the actual part of interest was the xc7a100tcsg324,
   since that is on the Arty A7-100T board. But here, the xc7a100tfgg676
   part is used; the xc7a100tcsg324 is handled later.

-  ``XRAY_ROI_TILEGRID`` – modify the bounding boxes to be a tight fit on
   your new part.

-  ``XRAY_IOI3_TILES`` – These tiles need special
   handling for an irregularity in Xilinx 7-series FPGAs. See the
   `comments <https://github.com/SymbiFlow/prjxray/blob/master/fuzzers/005-tilegrid/generate_full.py#L401>`__
   in the 005 fuzzer for more information.

`This <https://github.com/SymbiFlow/prjxray/blob/master/settings/artix7_100t.sh>`__
is what the new settings file looked like in the example.

Source this new settings file:

::

   source settings/<new_device>.sh

Step 3
~~~~~~

The project needs to know which device is now available and which fabric it
uses. Because some devices share the same fabric, this mapping needs to be
done manually. Edit the device.yaml file for the used family under
settings/<familiy>/device.yaml be adding the device-fabric mapping:

::

  # device to fabric mapping
  "xc7a200t":
    fabric: "xc7a200t"
  "xc7a100t":
    fabric: "xc7a100t"
  "xc7a50t":
    fabric: "xc7a50t"
  "xc7a35t":
    fabric: "xc7a50t"

Now, generate all device information for the family:

::

  make db-prepare-artix7

Step 4
~~~~~~

Edit the top Makefile

-  Update the Makefile by adding the new device to the `correct
   list <https://github.com/tcal-x/prjxray/blob/fbf4dd897d5a1025ebfeb7c51c5077a6b6c9bc47/Makefile#L171>`__,
   so that the Makefile generates targets for the new device (used in
   Step 4). ``<new_device>`` is the basename of the new settings file
   that you just created.

::

   <FAMILY>_PARTS=<existing_devices> <new_device>

-  In our running example, we add ``artix7_100t`` to ``ARTIX_PARTS``:

::

   ARTIX_PARTS=artix7_200t artix7_100t

Step 5
~~~~~~

Make sure you’ve sourced your new device settings file (see the end of
step 2) and generated the device information (see the end of set 3). Now it is
time to run some fuzzers to figure out how the tiles on your new device are
connected.

Make the following target, with ``<new_device>`` as above, and setting
the parallelism factor ``-j<n>`` appropriate for the number of cores
your host has. The make job can benefit from large numbers of cores.

::

   make -j<n> MAX_VIVADO_PROCESS=<n> db-part-only-<new_device>

Again, ``<new_device>`` must match the base name of the new settings
file that was added. For example,

::

   make -j32 MAX_VIVADO_PROCESS=32 db-part-only-artix7_100t

-  It should run fuzzers 000, 001, 005, 072, 073, 074, and 075.

-  005 will take a long time. Using multiple cores will help.

-  074 *will fail* the first time, since it hasn’t been told to ignore
   certain wires.

   -  After it fails, go to the build directory
      ``cd fuzzers/074-dump_all/build_<XRAY_PART>`` (this is the
      ``XRAY_PART`` from the new settings script; in our example, the
      build directory is
      ``fuzzers/074-dump_all/build_xc7a100tfgg676-1/``).
   -  Run
      ``python3 ../analyze_errors.py --output_ignore_list  > new-ignored``
   -  Inspect and compare ``new-ignored`` against existing ignored wire
      files in ``../ignored_wires/``.
   -  If it looks good, copy it to an appropriately-named file:
      ``cp new-ignored ../ignored_wires/artix7/<XRAY_PART>_ignored_wires.txt``
      (in our example, it is
      ``../ignored_wires/artix7/xc7a100tfgg676-1_ignored_wires.txt``).
   -  Add it:
      ``git add ../ignored_wires/artix7/<XRAY_PART>_ignored_wires.txt``

-  Return to prjxray/ directory, and clean up 074 to prepare for the
   rerun: ``make -C fuzzers/074-dump-all clean``

-  Rerun the top make command,
   e.g. ``make -j32 MAX_VIVADO_PROCESS=32 db-part-only-artix7_100t``

Step 6
~~~~~~

The next task is handling the extra parts – those not fully bonded out.
These are usually the parts you actually have on the boards you buy.

After the fabric data is generated with step 5, an further target can generate
all extra parts for the device.

::

   make -j<n> MAX_VIVADO_PROCESS=<n> db-roi-only-<new_device>

Step 7
~~~~~~

Do a spot check.

-  Check that there are new part directories in the database under the family subdirectory, for example:

::

   $ ll database/artix7/xc7a*
   xc7a35tftg256-1:
   total 48
   -rw-rw-r-- 1 daniel daniel  8234 Jan  9 13:01 package_pins.csv
   -rw-rw-r-- 1 daniel daniel 18816 Jan  9 13:01 part.json
   -rw-rw-r-- 1 daniel daniel 13099 Jan  9 13:01 part.yaml

   xc7a50t:
   total 15480
   -rw-rw-r-- 1 daniel daniel  695523 Jan  9 12:53 node_wires.json
   -rw-rw-r-- 1 daniel daniel 8587682 Jan  9 12:53 tileconn.json
   -rw-rw-r-- 1 daniel daniel 6562851 Jan  9 10:31 tilegrid.json

   xc7a50tfgg484-1:
   total 52
   -rw-rw-r-- 1 daniel daniel 13056 Jan  9 09:54 package_pins.csv
   -rw-rw-r-- 1 daniel daniel 18840 Jan  9 09:58 part.json
   -rw-rw-r-- 1 daniel daniel 13099 Jan  9 09:58 part.yaml

Note: These changes/additions under ``database/`` do *not* get checked
in. They are in the ``prjxray-db`` repo. This spot check is to make sure
that your changes in ``prjxray`` will do the right thing when the
official database is fully rebuilt. See “Database Updates” below for
more information.

Step 8
~~~~~~

Assuming everything looks good, commit to your ``prjxray`` fork/branch.
You should have a new file under settings/, a new ignored_wires file,
and a modified Makefile (see the `initial
PR <https://github.com/SymbiFlow/prjxray/pull/1313/files?file-filters%5B%5D=>`__
of the example for reference).

::

   git add Makefile settings/artix7_100t.sh
   git status
   git commit --signoff

Step 9
~~~~~~

Push to GitHub:

::

   git push origin <new_branch_name>

Then make a pull request. Navigate to the GitHub page for your
``prjxray`` fork/branch, and click the “New pull request” button.
Making the pull request will kick off continuous integration tests.
Watch the results and fix any issues.

Database Updates
~~~~~~~~~~~~~~~~

The process above (steps 4 and 5) will create some new files and modify
some existing files under database/, which is a different repo,
``prjxray-db``.

To test these changes before the next official prjxray-db gets built
(and even before your PR on prjxray is merged), you can put these
changes on your own fork of prjxray-db, and then test them in the
context of
`symbiflow-arch-defs <https://github.com/SymbiFlow/symbiflow-arch-defs>`__.

To put the db updates on your own fork, create your fork of
https://github.com/SymbiFlow/prjxray-db if you haven’t already. Then
follow one of the approaches suggested in the checked solution of this
StackOverflow
`post <https://stackoverflow.com/questions/25545613/how-can-i-push-to-my-fork-from-a-clone-of-the-original-repo>`__.

You are NEVER going to send a pull request on `prjxray-db`. The database is always rebuilt
from scratch. After your changes on prjxray are merged, they will
reflected in the next prjxray-db rebuild. The changes submitted to your
prjxray-db fork are only for your own testing.

To use your new repo/branch under
symbiflow-arch-defs/third_party/prjxray-db/, you will need to change the
submodule reference to point to your fork/branch of ``prjxray-db``.