Juno: Use TZC-400 driver calls

This patch replaces direct accesses to the TZC-400 registers by the
appropiate calls to the generic driver available in the Trusted
Firmware in order to initialize the TrustZone Controller.

Functions related to the initialization of the secure memory,
like the TZC-400 configuration, have been moved to a new file
'plat_security.c'. This reorganization makes easier to set up
the secure memory from any BL stage.

TZC-400 initialization has been moved from BL1 to BL2 because BL1
does not access the non-secure memory. It is BL2's responsibility
to enable and configure the TZC-400 before loading the next BL
images.

In Juno, BL3-0 initializes some of the platform peripherals, like
the DDR controller. Thus, BL3-0 must be loaded before configuring
the TrustZone Controller. As a consequence, the IO layer
initialization has been moved to early platform initialization.

Fixes ARM-software/tf-issues#234

Change-Id: I83dde778f937ac8d2996f7377e871a2e77d9490e
Juno: Reserve some DDR-DRAM for secure use

This patch configures the TrustZone Controller in Juno to split
the 2GB DDR-DRAM memory at 0x80000000 into Secure and Non-Secure
regions:

- Secure DDR-DRAM: top 16 MB, except for the last 2 MB which are
  used by the SCP for DDR retraining
- Non-Secure DDR-DRAM: remaining DRAM starting at base address

Build option PLAT_TSP_LOCATION selects the location of the secure
payload (BL3-2):

- 'tsram' : Trusted SRAM (default option)
- 'dram'  : Secure region in the DDR-DRAM (set by the TrustZone
            controller)

The MMU memory map has been updated to give BL2 permission to load
BL3-2 into the DDR-DRAM secure region.

Fixes ARM-software/tf-issues#233

Change-Id: I6843fc32ef90aadd3ea6ac4c7f314f8ecbd5d07b
Juno: Support entry into a standby state

This patch adds support on the Juno platform for entering a wfi in
response to a PSCI CPU_SUSPEND call where the state type is a
standby state.

Change-Id: I0a102dee1f8d2ad936c63ad1d1d3ad001a4a4768
FVP: keep shared data in Trusted SRAM

This patch deprecates the build option to relocate the shared data
into Trusted DRAM in FVP. After this change, shared data is always
located at the base of Trusted SRAM. This reduces the complexity
of the memory map and the number of combinations in the build
options.

Fixes ARM-software/tf-issues#257

Change-Id: I68426472567b9d8c6d22d8884cb816f6b61bcbd3
Merge pull request #215 from jcastillo-arm/jc/juno_mem_6

Jc/juno mem 6
Merge pull request #216 from vikramkanigiri/vk/juno_standby_support

Juno: Support entry into a standby state
Merge pull request #217 from jcastillo-arm/jc/tf-issues/257

FVP: keep shared data in Trusted SRAM
Add support for level specific cache maintenance operations

This patch adds level specific cache maintenance functions
to cache_helpers.S. The new functions 'dcsw_op_levelx',
where '1 <= x <= 3', allow to perform cache maintenance by
set/way for that particular level of cache.  With this patch,
functions to support cache maintenance upto level 3 have
been implemented since it is the highest cache level for
most ARM SoCs.

These functions are now utilized in CPU specific power down
sequences to implement them as mandated by processor specific
technical reference manual.

Change-Id: Icd90ce6b51cff5a12863bcda01b93601417fd45c
Apply errata workarounds only when major/minor revisions match.

Prior to this patch, the errata workarounds were applied for any version
of the CPU in the release build and in the debug build an assert
failure resulted when the revision did not match. This patch applies
errata workarounds in the Cortex-A57 reset handler only if the 'variant'
and 'revision' fields read from the MIDR_EL1 match. In the debug build,
a warning message is printed for each errata workaround which is not
applied.

The patch modifies the register usage in 'reset_handler` so
as to adhere to ARM procedure calling standards.

Fixes ARM-software/tf-issues#242

Change-Id: I51b1f876474599db885afa03346e38a476f84c29
Optimize barrier usage during Cortex-A57 power down

This the patch replaces the DSB SY with DSB ISH
after disabling L2 prefetches during the Cortex-A57
power down sequence.

Change-Id: I048d12d830c1b974b161224eff079fb9f8ecf52d
Optimize Cortex-A57 cluster power down sequence on Juno

This patch optimizes the Cortex-A57 cluster power down sequence by not
flushing the Level1 data cache. The L1 data cache and the L2 unified
cache are inclusive. A flush of the L2 by set/way flushes any dirty
lines from the L1 as well. This is a known safe deviation from the
Cortex-A57 TRM defined power down sequence. This optimization can be
enabled by the platform through the 'SKIP_A57_L1_FLUSH_PWR_DWN' build
flag. Each Cortex-A57 based platform must make its own decision on
whether to use the optimization.

This patch also renames the cpu-errata-workarounds.md to
cpu-specific-build-macros.md as this facilitates documentation
of both CPU Specific errata and CPU Specific Optimization
build macros.

Change-Id: I299b9fe79e9a7e08e8a0dffb7d345f9a00a71480