arm64: Turn architectural register accessors into inline functions

Accesses to architectural registers should be really fast -- they're
just registers, after all. In fact, the arm64 architecture uses them for
some timing-senstive uses like the architectural timer. A read should be:
one instruction, no data dependencies, done.

However, our current coreboot framework wraps each of these accesses
into a separate function. Suddenly you have to spill registers on a
stack, make a function call, move your stack pointer, etc. When running
without MMU this adds a significant enough delay to cause timing
problems when bitbanging a UART on SDM845.

This patch replaces all those existing functions with static inline
definitions in the header so they will get reduced to a single
instruction as they should be. Also use some macros to condense the code
a little since they're all so regular, which should make it easier to
add more in the future. This patch also expands all the data types to
uint64_t since that's what the actual assembly instruction accesses,
even if the register itself only has 32 bits (the others will be ignored
by the processor and set to 0 on read). Arm regularly expands registers
as they add new bit fields to them with newer iterations of the
architecture anyway, so this just prepares us for the inevitable.

Change-Id: I2c41cc3ce49ee26bf12cd34e3d0509d8e61ffc63
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/27881
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

1 files changed, 0 insertions, 2 deletions

diff --git a/src/arch/arm64/armv8/Makefile.inc b/src/arch/arm64/armv8/Makefile.inc
index db7bd33793..44ebdef815 100644
--- a/src/arch/arm64/armv8/Makefile.inc
+++ b/src/arch/arm64/armv8/Makefile.inc
@@ -15,8 +15,6 @@
 ##
 ################################################################################
 
-subdirs-y += lib/
-
 ifeq ($(CONFIG_ARCH_ARMV8_EXTENSION),0)
 march = armv8-a
 else