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

Remove variables from .data section ...

Update code base to remove variables from the .data section,
mainly by using const static data where possible and adding
the const specifier as required. Most changes are to the IO
subsystem, including the framework APIs. The FVP power
management code is also affected.

Delay initialization of the global static variable,
next_image_type in bl31_main.c, until it is realy needed.
Doing this moves the variable from the .data to the .bss
section.

Also review the IO interface for inconsistencies, using
uintptr_t where possible instead of void *. Remove the
io_handle and io_dev_handle typedefs, which were
unnecessary, replacing instances with uintptr_t.

Fixes ARM-software/tf-issues#107.

Change-Id: I085a62197c82410b566e4698e5590063563ed304

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

Always use named structs in header files ...

Add tag names to all unnamed structs in header files. This
allows forward declaration of structs, which is necessary to
reduce header file nesting (to be implemented in a subsequent
commit).

Also change the typedef names across the codebase to use the _t
suffix to be more conformant with the Linux coding style. The
coding style actually prefers us not to use typedefs at all but
this is considered a step too far for Trusted Firmware.

Also change the IO framework structs defintions to use typedef'd
structs to be consistent with the rest of the codebase.

Change-Id: I722b2c86fc0d92e4da3b15e5cab20373dd26786f

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

Move FVP power driver to FVP platform ...

Move the FVP power driver to a directory under the FVP platform
port as this is not a generically usable driver.

Change-Id: Ibc78bd88752eb3e3964336741488349ac345f4f0

Add standby state support in PSCI cpu_suspend api ...

This patch adds support in the generic PSCI implementation to call a
platform specific function to enter a standby state using an example
implementation in ARM FVP port

Fixes ARM-software/tf-issues#94
Change-Id: Ic1263fcf25f28e09162ad29dca954125f9aa8cc9

fvp: clear a pending cluster power off request ...

The last CPU in a cluster is responsible for issuing the cluster power
down request to the FVP power controller. If another CPU in this
cluster wakes up before the last CPU enters WFI then the cluster power
down request remains pending. If this request is not cancelled and the
newly woken up CPU enters a simple WFI later, the power controller
powers the cluster down. This leads to unpredictable behaviour.

This patch fixes this issue by ensuring that the first CPU to wake up
in a cluster writes its MPIDR to the power controller's PPONR. This
cancels any pending cluster power down request.

Change-Id: I7e787adfd6c9a0bd7308390e3309d46f35c01086

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>