Revert "Remove unused top-level readme file"

This reverts commit fbf26ee13a2f8fde77cb793e9faf998e17135e2b.

The readme file removed by this commit is indeed not used by ReadTheDocs
but it is the one displayed on:
https://git.trustedfirmware.org/TF-A/tf-a-tests.git/about

Change-Id: I267a247bb32c570e254553d65b93bf70cdaf76e4
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
diff --git a/readme.rst b/readme.rst
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+Trusted Firmware-A Tests - version 2.3
+======================================
+
+The Trusted Firmware-A Tests (TF-A-Tests) is a suite of baremetal tests to
+exercise the `Trusted Firmware-A (TF-A)`_ features from the Normal World. It
+enables strong TF-A functional testing without dependency on a Rich OS. It
+mainly interacts with TF-A through its SMC interface.
+
+It provides a basis for TF-A developers to validate their own platform ports and
+add their own test cases.
+
+The following TF-A features are currently tested to some extent (this list is
+not exhaustive):
+
+-  `SMC Calling Convention`_
+-  `Power State Coordination Interface (PSCI)`_
+-  `Software Delegated Exception Interface (SDEI)`_
+-  `Performance Measurement Framework (PMF)`_
+-  Communication and interaction with the `Test Secure Payload (TSP)`_
+-  `Firmware update`_ (or recovery mode)
+-  `EL3 payload`_ boot flow
+-  `Secure partition`_ support
+
+These tests are not a compliance test suite for the Arm interface standards used
+in TF-A (such as PSCI).
+
+They do not cover 100% of the TF-A code. The fact that all tests pass does not
+mean that TF-A is free of bugs.
+
+They are not reference code. They should not be considered as the official way
+to test hardware/firmware features. Instead, they are provided as example code
+to experiment with and improve on.
+
+License
+-------
+
+The software is provided under a BSD-3-Clause `license`_. Contributions to this
+project are accepted under the same license with developer sign-off as
+described in the `Contributing Guidelines`_.
+
+This project contains code from other projects as listed below. The original
+license text is included in those source files.
+
+-  The libc source code is derived from `FreeBSD`_ and `SCC`_. FreeBSD uses
+   various BSD licenses, including BSD-3-Clause and BSD-2-Clause. The SCC code
+   is used under the BSD-3-Clause license with the author's permission.
+
+-  The `LLVM compiler-rt`_ source code is disjunctively dual licensed
+   (NCSA OR MIT). It is used by this project under the terms of the NCSA
+   license (also known as the University of Illinois/NCSA Open Source License),
+   which is a permissive license compatible with BSD-3-Clause. Any
+   contributions to this code must be made under the terms of both licenses.
+
+This release
+------------
+
+This release makes a wide range of tests available for validating the functionality
+of TF-A as well as several improvements to test framework and test suite.
+
+Please refer to the `change log`_ for more details of the features, known issues and
+limitations in the current release.
+
+
+Platforms
+`````````
+
+Juno Arm Development Platform
+'''''''''''''''''''''''''''''
+
+The AArch64 build of this release has been tested on variants r0, r1 and r2 of
+the `Juno Arm Development Platform`_. The AArch32 build has only been tested on
+variant r0.
+
+Armv8 Architecture Fixed Virtual Platforms
+''''''''''''''''''''''''''''''''''''''''''
+
+The AArch64 build has been tested on the following Armv8 Architecture Fixed
+Virtual Platforms (`FVP`_):
+
+-  ``FVP_Base_AEMv8A-AEMv8A``
+-  ``FVP_Base_Cortex-A35x4``
+-  ``FVP_Base_Cortex-A57x4-A53x4``
+-  ``FVP_Base_RevC-2xAEMv8A``
+-  ``Foundation_Platform``
+
+The AArch32 build has been tested on the following `FVP`_\ s:
+
+-  ``FVP_Base_Cortex-A32x4``
+-  ``FVP_Base_RevC-2xAEMv8A``
+
+NOTE: Unless otherwise stated, the model version is version 11.9, build 41.
+
+System Guidance for Infrastructure Fixed Virtual Platforms
+''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
+
+The AArch64 build has been tested on the following Fixed Virtual Platforms
+(`FVP`_):
+
+-  ``FVP_CSS_SGI-575``
+-  ``FVP_RD_N1Edge``
+
+NOTE:
+
+-  For ``FVP_CSS_SGI-575`` and ``FVP_RD_N1Edge``, internal version of the
+   models were used.
+
+Still to come
+`````````````
+
+-  More tests.
+-  Support for new platforms.
+-  Design improvements.
+-  Stability improvements.
+-  Enhance test framework to make it easier to implement tests.
+-  Fixing known issues (see the `change log`_ for more details).
+
+
+Getting started
+---------------
+
+Get the TF-A Tests source code from `trustedfirmware.org`_.
+
+See the `User Guide`_ for instructions on how to install, build and use the TF-A
+Tests.
+
+See the `Design Guide`_ for information on how the TF-A Tests internally work.
+
+See the `Porting Guide`_ for information about how to use this software on
+another Armv8-A platform.
+
+See the `Contributing Guidelines`_ for information on how to contribute to this
+project.
+
+--------------
+
+*Copyright (c) 2018-2020, Arm Limited. All rights reserved.*
+
+.. _Contributing Guidelines: contributing.rst
+.. _license: license.rst
+.. _change log: docs/change-log.rst
+.. _Design Guide: docs/design.rst
+.. _Porting Guide: docs/porting-guide.rst
+.. _User Guide: docs/user-guide.rst
+.. _FVP: https://developer.arm.com/products/system-design/fixed-virtual-platforms
+.. _Juno Arm Development Platform: https://developer.arm.com/products/system-design/development-boards/juno-development-board
+
+.. _Power State Coordination Interface (PSCI): PSCI_
+.. _PSCI: http://infocenter.arm.com/help/topic/com.arm.doc.den0022d/Power_State_Coordination_Interface_PDD_v1_1_DEN0022D.pdf
+.. _Software Delegated Exception Interface (SDEI): SDEI_
+.. _SDEI: http://infocenter.arm.com/help/topic/com.arm.doc.den0054a/ARM_DEN0054A_Software_Delegated_Exception_Interface.pdf
+.. _SMC Calling Convention: http://infocenter.arm.com/help/topic/com.arm.doc.den0028b/ARM_DEN0028B_SMC_Calling_Convention.pdf
+
+.. _trustedfirmware.org: https://git.trustedfirmware.org/TF-A/tf-a-tests.git
+
+.. _Trusted Firmware-A (TF-A): TF-A_
+.. _TF-A: https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/about
+.. _Test Secure Payload (TSP): TSP_
+.. _TSP: https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/tree/bl32/tsp
+.. _Performance Measurement Framework (PMF): PMF_
+.. _PMF: https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/about/docs/firmware-design.rst#performance-measurement-framework
+.. _Firmware update: https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/about/docs/firmware-update.rst
+.. _EL3 payload: https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/about/docs/user-guide.rst#el3-payloads-alternative-boot-flow
+.. _Secure partition: https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/about/docs/secure-partition-manager-design.rst
+
+.. _issue tracker: https://developer.trustedfirmware.org/project/board/9/
+.. _mailing list: https://lists.trustedfirmware.org/mailman/listinfo/tf-a-tests