Split platform.h into separate headers ...

Previously, platform.h contained many declarations and definitions
used for different purposes. This file has been split so that:

* Platform definitions used by common code that must be defined
  by the platform are now in platform_def.h. The exact include
  path is exported through $PLAT_INCLUDES in the platform makefile.

* Platform definitions specific to the FVP platform are now in
  /plat/fvp/fvp_def.h.

* Platform API declarations specific to the FVP platform are now
  in /plat/fvp/fvp_private.h.

* The remaining platform API declarations that must be ported by
  each platform are still in platform.h but this file has been
  moved to /include/plat/common since this can be shared by all
  platforms.

Change-Id: Ieb3bb22fbab3ee8027413c6b39a783534aee474a

Introduce platform api to access an ARM GIC ...

This patch introduces a set of functions which allow generic firmware
code e.g. the interrupt management framework to access the platform
interrupt controller. APIs for finding the type and id of the highest
pending interrupt, acknowledging and EOIing an interrupt and finding
the security state of an interrupt have been added. It is assumed that
the platform interrupt controller implements the v2.0 of the ARM GIC
architecture specification. Support for v3.0 of the specification for
managing interrupts in EL3 and the platform port will be added in the
future.

Change-Id: Ib3a01c2cf3e3ab27806930f1be79db2b29f91bcf

Introduce interrupt registration framework in BL3-1 ...

This patch introduces a framework for registering interrupts routed to
EL3. The interrupt routing model is governed by the SCR_EL3.IRQ and
FIQ bits and the security state an interrupt is generated in. The
framework recognizes three type of interrupts depending upon which
exception level and security state they should be handled in
i.e. Secure EL1 interrupts, Non-secure interrupts and EL3
interrupts. It provides an API and macros that allow a runtime service
to register an handler for a type of interrupt and specify the routing
model. The framework validates the routing model and uses the context
management framework to ensure that it is applied to the SCR_EL3 prior
to entry into the target security state. It saves the handler in
internal data structures. An API is provided to retrieve the handler
when an interrupt of a particular type is asserted. Registration is
expected to be done once by the primary CPU. The same handler and
routing model is used for all CPUs.

Support for EL3 interrupts will be added to the framework in the
future. A makefile flag has been added to allow the FVP port choose
between ARM GIC v2 and v3 support in EL3. The latter version is
currently unsupported.

A framework for handling interrupts in BL3-1 will be introduced in
subsequent patches. The default routing model in the absence of any
handlers expects no interrupts to be routed to EL3.

Change-Id: Idf7c023b34fcd4800a5980f2bef85e4b5c29e649

Correct usage of data and instruction barriers ...

The current code does not always use data and instruction
barriers as required by the architecture and frequently uses
barriers excessively due to their inclusion in all of the
write_*() helper functions.

Barriers should be used explicitly in assembler or C code
when modifying processor state that requires the barriers in
order to enable review of correctness of the code.

This patch removes the barriers from the helper functions and
introduces them as necessary elsewhere in the code.

PORTING NOTE: check any port of Trusted Firmware for use of
system register helper functions for reliance on the previous
barrier behaviour and add explicit barriers as necessary.

Fixes ARM-software/tf-issues#92

Change-Id: Ie63e187404ff10e0bdcb39292dd9066cb84c53bf

Reduce deep nesting of header files ...

Reduce the number of header files included from other header
files as much as possible without splitting the files. Use forward
declarations where possible. This allows removal of some unnecessary
"#ifndef __ASSEMBLY__" statements.

Also, review the .c and .S files for which header files really need
including and reorder the #include statements alphabetically.

Fixes ARM-software/tf-issues#31

Change-Id: Iec92fb976334c77453e010b60bcf56f3be72bd3e

Refactor GIC header files ...

Move the function prototypes from gic.h into either gic_v2.h or
gic_v3.h as appropriate. Update the source files to include the
correct headers.

Change-Id: I368cfda175cdcbd3a68f46e2332738ec49048e19

Fix implementation and users of gicd_set_ipriorityr() ...

Make gicd_set_ipriorityr() actually write to the priority register.

Also correct callers of this function which want the highest priority
to use the value zero as this is the highest priority value according
to the ARM Generic Interrupt Controller Architecture Specification.

To make this easier to get right, we introduce defines for the lowest
and highest priorities for secure and non-secure interrupts.

Fixes ARM-software/tf-issues#21

Signed-off-by: Jon Medhurst <tixy@linaro.org>

fvp: rename fvp_* files to plat_* ...

The FVP platform has a few filenames that begin with fvp_.  These are
renamed to plat_ to make it easier to use the FVP port as a template.

Change-Id: I601e6256d5ef3bae81a2e1f5df6de56db5b27069
Signed-off-by: Ryan Harkin <ryan.harkin@linaro.org>