doc: Migrate content from User Guide and update it

The User Guide document holds many different bits of
information that are not always related to each other. These
are moved out into files where information is grouped tightly
together.

This also updates build instructions and environment variable
instructions to link to the relevent parts of the TF-A user guide
and use more recent versions of compiler, respetively.

Change-Id: Iace851f93c7dea8f154ae52a2665dd599f2e5d72
Signed-off-by: Paul Beesley <paul.beesley@arm.com>
Signed-off-by: Jimmy Brisson <jimmy.brisson@arm.com>
diff --git a/docs/getting_started/build.rst b/docs/getting_started/build.rst
new file mode 100644
index 0000000..cb8d358
--- /dev/null
+++ b/docs/getting_started/build.rst
@@ -0,0 +1,294 @@
+Building TF-A Tests
+===================
+
+-  Before building TF-A Tests, the environment variable ``CROSS_COMPILE`` must
+   point to the cross compiler.
+
+   For AArch64:
+
+   ::
+
+       export CROSS_COMPILE=<path-to-aarch64-gcc>/bin/aarch64-none-elf-
+
+   For AArch32:
+
+   ::
+
+       export CROSS_COMPILE=<path-to-aarch32-gcc>/bin/arm-eabi-
+
+-  Change to the root directory of the TF-A Tests source tree and build.
+
+   For AArch64:
+
+   ::
+
+       make PLAT=<platform>
+
+   For AArch32:
+
+   ::
+
+       make PLAT=<platform> ARCH=aarch32
+
+   Notes:
+
+   -  If ``PLAT`` is not specified, ``fvp`` is assumed by default. See the
+      `Summary of build options`_ for more information on available build
+      options.
+
+   -  By default this produces a release version of the build. To produce a
+      debug version instead, build the code with ``DEBUG=1``.
+
+   -  The build process creates products in a ``build/`` directory tree,
+      building the objects and binaries for each test image in separate
+      sub-directories. The following binary files are created from the
+      corresponding ELF files:
+
+      -  ``build/<platform>/<build-type>/tftf.bin``
+      -  ``build/<platform>/<build-type>/ns_bl1u.bin``
+      -  ``build/<platform>/<build-type>/ns_bl2u.bin``
+      -  ``build/<platform>/<build-type>/el3_payload.bin``
+      -  ``build/<platform>/<build-type>/cactus_mm.bin``
+      -  ``build/<platform>/<build-type>/cactus.bin``
+      -  ``build/<platform>/<build-type>/ivy.bin``
+      -  ``build/<platform>/<build-type>/quark.bin``
+
+      where ``<platform>`` is the name of the chosen platform and ``<build-type>``
+      is either ``debug`` or ``release``. The actual number of images might differ
+      depending on the platform.
+
+      Refer to the sections below for more information about each image.
+
+-  Build products for a specific build variant can be removed using:
+
+   ::
+
+       make DEBUG=<D> PLAT=<platform> clean
+
+   ... where ``<D>`` is ``0`` or ``1``, as specified when building.
+
+   The build tree can be removed completely using:
+
+   ::
+
+       make realclean
+
+-  Use the following command to list all supported build commands:
+
+   ::
+
+       make help
+
+TFTF test image
+```````````````
+
+``tftf.bin`` is the main test image to exercise the TF-A features. The other
+test images provided in this repository are optional dependencies that TFTF
+needs to test some specific features.
+
+``tftf.bin`` may be built independently of the other test images using the
+following command:
+
+::
+
+   make PLAT=<platform> tftf
+
+In TF-A boot flow, ``tftf.bin`` replaces the ``BL33`` image and should be
+injected in the FIP image. This might be achieved by running the following
+command from the TF-A root directory:
+
+::
+
+    BL33=tftf.bin make PLAT=<platform> fip
+
+Please refer to the `TF-A User guide`_ for further details.
+
+NS_BL1U and NS_BL2U test images
+```````````````````````````````
+
+``ns_bl1u.bin`` and ``ns_bl2u.bin`` are test images that exercise the `Firmware
+Update`_ (FWU) feature of TF-A [#]_. Throughout this document, they will be
+referred as the `FWU test images`.
+
+In addition to updating the firmware, the FWU test images also embed some tests
+that exercise the `FWU state machine`_ implemented in the TF-A. They send valid
+and invalid SMC requests to the TF-A BL1 image in order to test its robustness.
+
+NS_BL1U test image
+''''''''''''''''''
+
+The ``NS_BL1U`` image acts as the `Application Processor (AP) Firmware Update
+Boot ROM`. This typically is the first software agent executing on the AP in the
+Normal World during a firmware update operation. Its primary purpose is to load
+subsequent firmware update images from an external interface, such as NOR Flash,
+and communicate with ``BL1`` to authenticate those images.
+
+The ``NS_BL1U`` test image provided in this repository performs the following
+tasks:
+
+-  Load FWU images from external non-volatile storage (typically flash memory)
+   to Non-Secure RAM.
+
+-  Request TF-A BL1 to copy these images in Secure RAM and authenticate them.
+
+-  Jump to ``NS_BL2U`` which carries out the next steps in the firmware update
+   process.
+
+This image may be built independently of the other test images using the
+following command:
+
+::
+
+   make PLAT=<platform> ns_bl1u
+
+NS_BL2U test image
+''''''''''''''''''
+
+The ``NS_BL2U`` image acts as the `AP Firmware Updater`. Its primary
+responsibility is to load a new set of firmware images from an external
+interface and write them into non-volatile storage.
+
+The ``NS_BL2U`` test image provided in this repository overrides the original
+FIP image stored in flash with the backup FIP image (see below).
+
+This image may be built independently of the other test images using the
+following command:
+
+::
+
+   make PLAT=<platform> ns_bl2u
+
+Putting it all together
+'''''''''''''''''''''''
+
+The FWU test images should be used in conjunction with the TFTF image, as the
+latter initiates the FWU process by corrupting the FIP image and resetting the
+target. Once the FWU process is complete, TFTF takes over again and checks that
+the firmware was successfully updated.
+
+To sum up, 3 images must be built out of the TF-A Tests repository in order to
+test the TF-A Firmware Update feature:
+
+-  ``ns_bl1u.bin``
+-  ``ns_bl2u.bin``
+-  ``tftf.bin``
+
+Once that's done, they must be combined in the right way.
+
+-  ``ns_bl1u.bin`` is a standalone image and does not require any further
+   processing.
+
+-  ``ns_bl2u.bin`` must be injected into the ``FWU_FIP`` image. This might be
+   achieved by setting ``NS_BL2U=ns_bl2u.bin`` when building the ``FWU_FIP``
+   image out of the TF-A repository. Please refer to the section `Building FIP
+   images with support for Trusted Board Boot`_ in the TF-A User Guide.
+
+-  ``tftf.bin`` must be injected in the standard FIP image, as explained
+   in section `TFTF test image`_.
+
+Additionally, on Juno platform, the FWU FIP must contain a ``SCP_BL2U`` image.
+This image can simply be a copy of the standard ``SCP_BL2`` image if no specific
+firmware update operations need to be carried on the SCP side.
+
+Finally, the backup FIP image must be created. This can simply be a copy of the
+standard FIP image, which means that the Firmware Update process will restore
+the original, uncorrupted FIP image.
+
+EL3 test payload
+````````````````
+
+``el3_payload.bin`` is a test image exercising the alternative `EL3 payload boot
+flow`_ in TF-A. Refer to the `EL3 test payload README file`_ for more details
+about its behaviour and how to build and run it.
+
+SPM test images
+```````````````
+
+This repository contains 3 Secure Partitions that exercise the `Secure Partition
+Manager`_ (SPM) in TF-A [#]_. Cactus-MM is designed to test the SPM
+implementation based on the `ARM Management Mode Interface`_ (MM), while Cactus
+and Ivy can test the SPM implementation based on the SPCI and SPRT draft
+specifications. Note that it isn't possible to use both communication mechanisms
+at once: If Cactus-MM is used Cactus and Ivy can't be used.
+
+They run in Secure-EL0 and perform the following tasks:
+
+-  Test that TF-A has correctly setup the secure partition environment: They
+   should be allowed to perform cache maintenance operations, access floating
+   point registers, etc.
+
+-  Test that TF-A accepts to change data access permissions and instruction
+   permissions on behalf of the Secure Partitions for memory regions the latter
+   owns.
+
+-  Test communication with SPM through either MM, or both SPCI and SPRT.
+
+They are only supported on AArch64 FVP. They can be built independently of the
+other test images using the following command:
+
+::
+
+   make PLAT=fvp cactus ivy cactus_mm
+
+In the TF-A boot flow, the partitions replace the ``BL32`` image and should be
+injected in the FIP image. To test SPM-MM with Cactus-MM, it is enough to use
+``cactus_mm.bin`` as BL32 image. To test the SPM based on SPCI and SPRT, it is
+needed to use ``sp_tool`` to build a Secure Partition package that can be used
+as BL32 image.
+
+To run the full set of tests in the Secure Partitions, they should be used in
+conjunction with the TFTF image.
+
+For SPM-MM, build TF-A following the `TF-A SPM User Guide`_ and the following
+commands can be used to build the tests:
+
+::
+
+    # TF-A-Tests repository:
+
+    make PLAT=fvp TESTS=spm-mm tftf cactus_mm
+
+For SPM based on SPCI and SPRT, build TF-A following the `TF-A SPM User Guide`_
+and the following commands can be used to build the tests:
+
+::
+
+    # TF-A-Tests repository:
+
+    make PLAT=fvp TESTS=spm tftf cactus ivy
+
+    # TF-A repository:
+
+    make sptool
+
+    tools/sptool/sptool -o sp_package.bin \
+        -i path/to/cactus.bin:path/to/cactus.dtb \
+        -i path/to/ivy.bin:path/to/ivy.dtb
+
+Please refer to the `TF-A User guide`_ for further details.
+
+--------------
+
+.. [#] Therefore, the Trusted Board Boot feature must be enabled in TF-A for
+       the FWU test images to work. Please refer the `TF-A User guide`_ for
+       further details.
+
+.. [#] Therefore, the Secure Partition Manager must be enabled in TF-A for
+       any of the test Secure Partitions to work. Please refer to the `TF-A User
+       guide`_ for further details.
+
+--------------
+
+*Copyright (c) 2019, Arm Limited. All rights reserved.*
+
+.. _EL3 payload boot flow: https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/about/docs/user-guide.rst#el3-payloads-alternative-boot-flow
+.. _TF-A User Guide: https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/about/docs/user-guide.rst
+.. _TF-A SPM User Guide: https://trustedfirmware-a.readthedocs.io/en/latest/components/secure-partition-manager-design.html#building-tf-a-with-secure-partition-support
+.. _Firmware Update: FWU_
+.. _EL3 test payload README file: ../el3_payload/README
+.. _FWU: https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/about/docs/firmware-update.rst
+.. _FWU state machine: https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/about/docs/firmware-update.rst#fwu-state-machine
+.. _Summary of build options: user-guide.rst#summary-of-build-options
+.. _Building FIP images with support for Trusted Board Boot: https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/about/docs/user-guide.rst#building-fip-images-with-support-for-trusted-board-boot
+.. _Secure partition Manager: https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/about/docs/secure-partition-manager-design.rst
+.. _ARM Management Mode Interface: http://infocenter.arm.com/help/topic/com.arm.doc.den0060a/DEN0060A_ARM_MM_Interface_Specification.pdf