Doc: Fix internal links in interrupt framework design guide ...

Some of the sections numbers have been incorrect since the document
structure has changed. Using references to sections rather than
hard-coded section numbers fixes the issue while making it more
future-proof to updates.

Change-Id: I80f5ab6a55a0073b1562a02ce2c9ec7d67cddfff
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>

Doc: Fix a formatting glitch ...

While converting the interrupt framework design document from Markdown
to reStructuredText format, see commit 6f6257476754 ("Convert
documentation to reStructuredText"), the structure of the document was
changed and one of the titles got lost. Fix that.

Change-Id: Ib3e6c1f9f01f16108fde3b89ceb624bd54049d2f
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>

Doc: Remove useless escape characters ...

Just like has been done in the porting guide a couple of patches
earlier, kill all escaped underscore characters in all documents.

Change-Id: I7fb5b806412849761d9221a6ce3cbd95ec43d611
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>

docs: Add Exception Handling Framework documentation ...

Change-Id: I77d38758d18ba6dda1652b1b1e644fbfb14386cc
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>

Update Arm TF references to TF-A ...

Update Arm Trusted Firmware references in the upstream documents to
Trusted Firmware-A (TF-A). This is for consistency with and
disambiguation from Trusted Firmware-M (TF-M).

Also update other Arm trademarks, e.g. ARM->Arm, ARMv8->Armv8-A.

Change-Id: I8bb0e18af29c6744eeea2dc6c08f2c10b20ede22
Signed-off-by: Dan Handley <dan.handley@arm.com>
Signed-off-by: David Cunado <david.cunado@arm.com>

interrupt-framework-design.rst: Cosmetic changes ...

Change-Id: Id2e2800af59ca35fc0c4cfdddd9f5c5afd56a4db
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>

TSPD: Require NS preemption along with EL3 exception handling ...

At present, the build option TSP_NS_INTR_ASYNC_PREEMPT controls how
Non-secure interrupt affects TSPs execution. When TSP is executing:

  1. When TSP_NS_INTR_ASYNC_PREEMPT=0, Non-secure interrupts are received
     at the TSP's exception vector, and TSP voluntarily preempts itself.

  2. When TSP_NS_INTR_ASYNC_PREEMPT=1, Non-secure interrupts causes a
     trap to EL3, which preempts TSP execution.

When EL3 exception handling is in place (i.e.,
EL3_EXCEPTION_HANDLING=1), FIQs are always trapped to EL3. On a system
with GICv3, pending NS interrupts while TSP is executing will be
signalled as FIQ (which traps to EL3). This situation necessitates the
same treatment applied to case (2) above.

Therefore, when EL3 exception handling is in place, additionally
require that TSP_NS_INTR_ASYNC_PREEMPT is set to one 1.

Strictly speaking, this is not required on a system with GICv2, but the
same model is uniformly followed regardless, for simplicity.

Relevant documentation updated.

Change-Id: I928a8ed081fb0ac96e8b1dfe9375c98384da1ccd
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>

Deprecate one EL3 interrupt routing model with EL3 exception handling ...

When ARM Trusted Firmware is built with EL3_EXCEPTION_HANDLING=1,
EL3 interrupts (INTR_TYPE_EL3) will always preempt both Non-secure and
secure execution.

The interrupt management framework currently treats EL3 interrupt
routing as valid. For the above reason, this patch makes them invalid
when EL3_EXCEPTION_HANDLING is in effect.

Change-Id: I95bca8f5dc8df8eb0ff6f305cfba098611522a39
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>

Convert documentation to reStructuredText ...

Due to recent issues in the rendering of the documentation on GitHub and
some long-standing issues like the lack of automatic table of content in
Markdown, the documentation has been converted to reStructuredText.
Basic constructs looks pretty similar to Markdown.

Automatically convert GitHub markdown documentation to reStructuredText
using pandoc.

Change-Id: If20b695acedc6d1b49c8d9fb64efd6b6ba23f4a9
Signed-off-by: Douglas Raillard <douglas.raillard@arm.com>