[PATCH v2] doc: add new driver guidelines

[Stephen Hemminger <stephen@networkplumber.org>]

From: Nandini Persad <nandinipersad361@gmail.com>

This document was created to assist contributors in creating DPDK drivers
and provides suggestions and guidelines on how to upstream effectively.

Co-authored-by: Ferruh Yigit <ferruh.yigit@amd.com>
Co-authored-by: Thomas Monjalon <thomas@monjalon.net>
Signed-off-by: Nandini Persad <nandinipersad361@gmail.com>
Reviewed-by: Stephen Hemminger <stephen@networkplumber.org>
---

v2 - review feedback
   - add co-author and reviewed-by

 doc/guides/contributing/index.rst      |   1 +
 doc/guides/contributing/new_driver.rst | 202 +++++++++++++++++++++++++
 2 files changed, 203 insertions(+)
 create mode 100644 doc/guides/contributing/new_driver.rst

diff --git a/doc/guides/contributing/index.rst b/doc/guides/contributing/index.rst
index dcb9b1fbf0..7fc6511361 100644
--- a/doc/guides/contributing/index.rst
+++ b/doc/guides/contributing/index.rst
@@ -15,6 +15,7 @@ Contributor's Guidelines
     documentation
     unit_test
     new_library
+    new_driver
     patches
     vulnerability
     stable
diff --git a/doc/guides/contributing/new_driver.rst b/doc/guides/contributing/new_driver.rst
new file mode 100644
index 0000000000..4aa1fd1d05
--- /dev/null
+++ b/doc/guides/contributing/new_driver.rst
@@ -0,0 +1,202 @@
+.. SPDX-License-Identifier: BSD-3-Clause
+   Copyright 2024 The DPDK contributors
+
+
+Upstreaming New DPDK Drivers Guide
+==================================
+
+The DPDK project continuously grows its ecosystem by adding support for new devices.
+This document is designed to assist contributors in creating DPDK
+drivers, also known as Poll Mode Drivers (PMD's).
+
+By having public support for a device, we can ensure accessibility across various
+operating systems and guarantee community maintenance in future releases.
+If a new device is similar to a device already supported by an existing driver,
+it is more efficient to update the existing driver.
+
+Here are our best practice recommendations for creating a new driver.
+
+
+Early Engagement with the Community
+-----------------------------------
+
+When creating a new driver, we highly recommend engaging with the DPDK
+community early instead of waiting the work to mature.
+
+These public discussions help align development of your driver with DPDK expectations.
+You may submit a roadmap before the release to inform the community of
+your plans. Additionally, sending a Request for Comments (RFC) early in
+the release cycle, or even during the prior release, is advisable.
+
+DPDK is mainly consumed via Long Term Support (LTS) releases.
+It is common to target a new PMD to a LTS release. For this, it is
+suggested to start upstreaming at least one release before a LTS release.
+
+
+Progressive Work
+----------------
+
+To continually progress your work, we recommend planning for incremental
+upstreaming across multiple patch series or releases.
+
+It's important to prioritize quality of the driver over upstreaming
+in a single release or single patch series.
+
+
+Finalizing
+----------
+
+Once the driver has been upstreamed, the author has
+a responsibility to the community to maintain it.
+
+This includes the public test report. Authors must send a public
+test report after the first upstreaming of the PMD. The same
+public test procedure may be reproduced regularly per release.
+
+After the PMD is upstreamed, the author should send a patch
+to update the website with the name of the new PMD and supported devices
+via the DPDK mailing list..
+
+For more information about the role of maintainers, see :doc:`patches`.
+
+
+
+Splitting into Patches
+----------------------
+
+We recommend that drivers are split into patches, so that each patch represents
+a single feature. If the driver code is already developed, it may be challenging
+to split. However, there are many benefits to doing so.
+
+Splitting patches makes it easier to understand a feature and clarifies the
+list of components/files that compose that specific feature.
+
+It also enables the ability to track from the source code to the feature
+it is enabled for and helps users to understand the reasoning and intention
+of implementation. This kind of tracing is regularly required
+for defect resolution and refactoring.
+
+Another benefit of splitting the codebase per feature is that it highlights
+unnecessary or irrelevant code, as any code not belonging to any specific
+feature becomes obvious.
+
+Git bisect is also more useful if patches are split per patch.
+
+The split should focus on logical features
+rather than file-based divisions.
+
+Each patch in the series must compile without errors
+and should maintain functionality.
+
+Enable the build as early as possible within the series
+to facilitate continuous integration and testing.
+This approach ensures a clear and manageable development process.
+
+We suggest splitting patches following this approach:
+
+* Each patch should be organized logically as a new feature.
+* Run test tools per patch (See :ref:`tool_list`:).
+* Update relevant documentation and <driver>.ini file with each patch.
+
+
+The following order in the patch series is as suggested below.
+
+The first patch should have the driver's skeleton which should include:
+
+* Maintainer's file update
+* Driver documentation
+* Document must have links to official product documentation web page
+* The  new document should be added into the index (`doc/guides/index.rst`)
+* Initial <drive>.ini file
+* Release notes announcement for the new driver
+
+
+The next patches should include basic device features.
+The following is suggested sample list to include in these patches:
+
+=======================   ========================
+Net                       Crypto
+=======================   ========================
+Initialization            Initialization
+Configure queues          Configure queues
+Start queues              Start queues
+Simple Rx / Tx            Simple Data Processing
+Statistics                Statistics
+Device info
+Link interrupt
+Burst mode info
+Promisc all-multicast
+RSS
+=======================   ========================
+
+
+Advanced features should be in the next group of patches.
+The suggestions for these, listed below, are in no specific order:
+
+=============================
+Net
+=============================
+Advanced Rx / Tx
+Scatter Support
+Vector Support
+TSO / LRO
+Rx / Tx Descriptor Status
+RX / Tx Queue Info
+Flow Offload
+Traffic Management/Metering
+Extended statistics
+Secondary Process Support
+FreeBSD / Windows Support
+Flow control
+FEC
+EEPROM access
+Register Dump
+Time Synchronization, PTP
+Perf documentation
+=============================
+
+
+After all features are enabled, if there is remaining base code that
+is not upstreamed, they can be upstreamed at the end of the patch series.
+However, we recommend these patches are still split into logical groups.
+
+
+Additional Suggestions
+----------------------
+
+* We recommend using DPDK macros instead of inventing new ones in the PMD.
+* Do not include unused headers. Use the ./devtools/process-iwyu.py tool.
+* Do not disable compiler warnings in the build file.
+* Do not use #ifdef with driver-defined macros, instead prefer runtime configuration.
+* Document device parameters in the driver guide.
+* Make device operations struct 'const'.
+* Use dynamic logging.
+* Do not use DPDK version checks in the upstream code.
+* Be sure to have SPDX license tags and copyright notice on each side.
+  Use ./devtools/check-spdx-tag.sh
+* Run the Coccinelle scripts ./devtools/cocci.sh which check for common cleanups such as
+  useless null checks before calling free routines.
+
+Dependencies
+------------
+
+At times, drivers may have dependencies to external software.
+For driver dependencies, same DPDK rules for dependencies applies.
+Dependencies should be publicly and freely available,
+or this is a blocker for upstreaming the driver.
+
+
+.. _tool_list:
+
+Test Tools
+----------
+
+Build and check the driver's documentation. Make sure there are no
+warnings and driver shows up in the relevant index page.
+
+Be sure to run the following test tools per patch in a patch series:
+
+* checkpatches.sh
+* check-git-log.sh
+* check-meson.py
+* check-doc-vs-code.sh
-- 
2.43.0