Docs: Add process for platform removal

Signed-off-by: Soby Mathew <soby.mathew@arm.com>
Change-Id: I3aefb16be610cb60270e8837bd8ce598c25a7f9a
diff --git a/docs/contributing/platform_deprecation.rst b/docs/contributing/platform_deprecation.rst
new file mode 100644
index 0000000..29e2e83
--- /dev/null
+++ b/docs/contributing/platform_deprecation.rst
@@ -0,0 +1,62 @@
+################################
+Platform deprecation and removal
+################################
+
+********************************************
+Process for Platform deprecation and removal
+********************************************
+
+A platform may need to be removed from upstream code due to lack of community
+interest or it may have reached end of life. The below section calls out the
+process for removing platform support from TF-M.
+
+    1. An email to the TF-M mailing list proposing the removal of the platform.
+
+    2. The merit of the proposal will be considered by the maintainers for a
+       period of 4 weeks and community can express their opinion on the same
+       during this time window. The platform owner can veto the proposal and
+       incase of multiple platform owners with differing opinion or community
+       having interest in the platform, then the project maintainer can work
+       with the platform owner and use their discretion to decide on the
+       proposal.
+
+    3. Once a decision is made to remove the platform, the platform is
+       considered to be in `deprecated` state as per platform support lifecyle
+       defined here: "https://developer.trustedfirmware.org/w/collaboration/project-maintenance-process/".
+       The platform will be marked as deprecated and the TF-M version after
+       which it will be removed will also be mentioned. Suitable build time
+       or runtime messages needs to be incorporated to the platform to warn
+       about the `deprecation`.
+
+    4. The project should strive to keep the `deprecated` platforms
+       building/running till the removal. This relies on platform owners being
+       still actively involved with the project and maintaining the platform.
+
+    5. Although this will be the usual process for platform deprecation and
+       eventual removal, the process still leaves room for the platform
+       deprecation to be cancelled after it has been marked as `deprecated`
+       due to evolving project and market requirements. This is left to
+       consensus between project maintainers and platform owner/s.
+
+    6. Once a platform has been removed, it can be added back in future and
+       this would follow the same guidelines as for a new platform contribution.
+
+****************************
+List of Deprecated Platforms
+****************************
+
+The below list calls out platforms marked for deprecation according to the
+above process and the platform will be removed soon after the mentioned
+release.
+
++------------------------------+-----------+-----------------------------------+
+|    Deprecated Platform       | Removed   | Comments                          |
+|                              | after     |                                   |
+|                              | release   |                                   |
++==============================+===========+===================================+
+|                              |           |                                   |
++------------------------------+-----------+-----------------------------------+
+
+--------------
+
+*Copyright (c) 2020, Arm Limited. All rights reserved.*
\ No newline at end of file
diff --git a/docs/introduction/readme.rst b/docs/introduction/readme.rst
index d77e848..213af41 100644
--- a/docs/introduction/readme.rst
+++ b/docs/introduction/readme.rst
@@ -153,6 +153,9 @@
         - `PSoc64.
           <https://www.cypress.com/documentation/product-brochures/cypress-psoc-64-secure-microcontrollers>`_
 
+The document :doc:`Platform Deprecation and Removal </docs/contributing/platform_deprecation>`
+lists the deprecated platforms planned to be removed from upstream.
+
 ####################
 Feedback and support
 ####################
diff --git a/platform/ext/index.rst b/platform/ext/index.rst
index e0d87f3..60422e9 100644
--- a/platform/ext/index.rst
+++ b/platform/ext/index.rst
@@ -7,6 +7,7 @@
 
     readme
     /platform/readme
+    /docs/contributing/platform_deprecation.rst
 
 .. toctree::
     :maxdepth: 4