Update docs with PMU security information ...

This patch adds information on the PMU configuration registers
and security considerations related to the PMU.

Signed-off-by: Petre-Ionut Tudor <petre-ionut.tudor@arm.com>
Change-Id: I36b15060b9830a77d3f47f293c0a6dafa3c581fb

doc: Split and expand coding style documentation ...

This patch expands the coding style documentation, splitting it
into two documents: the core style rules and extended guidelines.
Note that it does not redefine or change the coding style (aside
from section 4.6.2) - generally, it is only documenting the
existing style in more detail.

The aim is for the coding style to be more readable and, in turn,
for it to be followed by more people. We can use this as a more
concrete reference when discussing the accepted style with external
contributors.

Change-Id: I87405ace9a879d7f81e6b0b91b93ca69535e50ff
Signed-off-by: Paul Beesley <paul.beesley@arm.com>
Signed-off-by: Petre-Ionut Tudor <petre-ionut.tudor@arm.com>

Remove -Wpadded warning ...

-Wpadded warns whenever the C compiler automatically includes any
padding in a structure. Because TF-A has a large number of structures,
this occurs fairly frequently and is incredibly verbose, and as such is
unlikely to ever be fixed.

The utility of this warning is also extremely limited - knowing that a
structure includes padding does not point to the existence of an error,
and is probably quite unlikely to indicate actually buggy behaviour.
Therefore, it's probably best to keep this warning off at all times.

Change-Id: I0797cb75f06b4fea0d2fdc16fd5ad978a31d76ec
Signed-off-by: Justin Chadwell <justin.chadwell@arm.com>

Merge "Remove unnecessary warning options" into integration

doc: Split the User Guide into multiple files ...

The User Guide document has grown organically over time and
now covers a wide range of topics, making it difficult to
skim read and extract information from. Currently, it covers
these topics and maybe a couple more:

- Requirements (hardware, tools, libs)
- Checking out the repo
- Basic build instructions
- A comprehensive list of build flags
- FIP packaging
- Building specifically for Juno
- Firmware update images
- EL3 payloads
- Preloaded BL33 boot flow
- Running on FVPs
- Running on Juno

I have separated these out into a few groups that become new
documents. Broadly speaking, build instructions for the tools,
for TF-A generally, and for specific scenarios are separated.
Content relating to specific platforms (Juno and the FVPs are
Arm-specific platforms, essentially) has been moved into the
documentation that is specific to those platforms, under
docs/plat/arm.

Change-Id: Ica87c52d8cd4f577332be0b0738998ea3ba3bbec
Signed-off-by: Paul Beesley <paul.beesley@arm.com>

Remove unnecessary warning options ...

Both -Wmissing-field-initializers and -Wsign-compare are both covered by
-Wextra which is enabled at W=1 anyway. Therefore, the explicit options
are not required.

Change-Id: I2e7d95b5fc14af7c70895859a7ebbeac5bc0d2a4
Signed-off-by: Justin Chadwell <justin.chadwell@arm.com>

doc: Convert internal links to RST format ...

Currently links between documents are using the format:

<path/to/><filename>.rst

This was required for services like GitHub because they render each
document in isolation - linking to another document is like linking
to any other file, just provide the full path.

However, with the new approach, the .rst files are only the raw
source for the documents. Once the documents have been rendered
the output is now in another format (HTML in our case) and so,
when linking to another document, the link must point to the
rendered version and not the .rst file.

The RST spec provides a few methods for linking between content.
The parent of this patch enabled the automatic creation of anchors
for document titles - we will use these anchors as the targets for
our links. Additional anchors can be added by hand if needed, on
section and sub-section titles, for example.

An example of this new format, for a document with the title
"Firmware Design" is :ref:`Firmware Design`.

One big advantage of this is that anchors are not dependent on
paths. We can then move documents around, even between directories,
without breaking any links between documents. Links will need to be
updated only if the title of a document changes.

Change-Id: I9e2340a61dd424cbd8fd1ecc2dc166f460d81703
Signed-off-by: Paul Beesley <paul.beesley@arm.com>

doc: Isolate security-related build options ...

Reference security specific build options from the user guide.

Change-Id: I0e1efbf47d914cf3c473104175c702ff1a80eb67
Signed-off-by: Ambroise Vincent <ambroise.vincent@arm.com>