doc: Begin adding a best practices document for board ports

To help guide developers down the right path, begin a document that
lists some best practices to follow when creating a new board port.

Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

doc/develop/board_best_practices.rst

@@ -0,0 +1,26 @@
+.. SPDX-License-Identifier: GPL-2.0+:
+
+Best Practices for Board Ports
+==============================
+
+In addition to the regular best practices such as using :doc:`checkpatch` and
+following the :doc:`docstyle` and the :doc:`codingstyle` there are some things
+which are specific to creating a new board port.
+
+* Implement :doc:`bootstd` to ensure that most operating systems will be
+  supported by the platform.
+
+* The platform defconfig file must be generated via `make savedefconfig`.
+
+* The Kconfig and Kbuild infrastructure supports using "fragments" that can be
+  used to apply changes on top of a defconfig file. These can be useful for
+  many things such as:
+
+  * Supporting different firmware locations (e.g. eMMC, SD, QSPI).
+
+  * Multiple board variants when runtime detection is not desired.
+
+  * Supporting different build types such as production and development.
+
+  Kconfig fragments should reside in the board directory itself rather than in
+  the top-level `configs/` directory.

doc/develop/index.rst

@@ -9,6 +9,7 @@ General
 .. toctree::
    :maxdepth: 1
 
+   board_best_practices
    codingstyle
    designprinciples
    docstyle