Make the spinlock implementation use ARMv8.1-LSE CAS instruction based
on a platform build option. The CAS-based implementation used to be
unconditionally selected for all ARM8.1+ platforms.

The previous CAS spinlock implementation had a bug wherein the spin_unlock()
implementation had an `sev` after `stlr` which is not sufficient. A dsb is
needed to ensure that the stlr completes prior to the sev. Having a dsb is
heavyweight and a better solution would be to use load exclusive semantics
to monitor the lock and wake up from wfe when a store happens to the lock.
The patch implements the same.

Change-Id: I5283ce4a889376e4cc01d1b9d09afa8229a2e522
Signed-off-by: Soby Mathew <soby.mathew@arm.com>
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>

This patch removes .arch "arm8.1-a" and "armv8-a"
directives which overwrite ASFLAGS_aarch64 option based
on ARM_ARCH_MINOR passed to Makefile and cause
translation errors like
"selected processor does not support `bti jc'"
for armv8.5-a targets when BTI support is enabled.

Change-Id: Idca5b66ed1e5d86e2188b0c0f16c3819990957c4
Signed-off-by: Alexei Fedorov <Alexei.Fedorov@arm.com>

The macro concisely expresses and requires architecture version to be at
least as required by its arguments. This would be useful when extending
Trusted Firmware functionality for future architecture revisions.

Replace similar usage in the current code base with the new macro.

Change-Id: I9dcd0aa71a663eabd02ed9632b8ce87611fa5a57
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>

To make software license auditing simpler, use SPDX[0] license
identifiers instead of duplicating the license text in every file.

NOTE: Files that have been imported by FreeBSD have not been modified.

[0]: https://spdx.org/

Change-Id: I80a00e1f641b8cc075ca5a95b10607ed9ed8761a
Signed-off-by: dp-arm <dimitris.papastamos@arm.com>

The ARMv8v.1 architecture extension has introduced support for far
atomics, which includes compare-and-swap. Compare and Swap instruction
is only available for AArch64.

Introduce build options to choose the architecture versions to target
ARM Trusted Firmware:

  - ARM_ARCH_MAJOR: selects the major version of target ARM
    Architecture. Default value is 8.

  - ARM_ARCH_MINOR: selects the minor version of target ARM
    Architecture. Default value is 0.

When:

  (ARM_ARCH_MAJOR > 8) || ((ARM_ARCH_MAJOR == 8) && (ARM_ARCH_MINOR >= 1)),

for AArch64, Compare and Swap instruction is used to implement spin
locks. Otherwise, the implementation falls back to using
load-/store-exclusive instructions.

Update user guide, and introduce a section in Firmware Design guide to
summarize support for features introduced in ARMv8 Architecture
Extensions.

Change-Id: I73096a0039502f7aef9ec6ab3ae36680da033f16
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>

This patch moves the assembly exclusive lock library code
`spinlock.S` into architecture specific folder `aarch64`.
A stub file which includes the file from new location is
retained at the original location for compatibility. The BL
makefiles are also modified to include the file from the new
location.

Change-Id: Ide0b601b79c439e390c3a017d93220a66be73543