ARM cores may have a per-core architected timer, which provides per-cpu
timers, attached to a GIC to deliver its per-processor interrupts via
PPIs. This is the most common case supported by QEMU in the virt
platform.
This patch introduces support for this timer abstracting the way the
timer registers are actually accessed. This is needed because different
architectures (for example ARMv7-R vs ARMv8-A) use different registers
and even the same architecture (ARMv8-A) can actually use different
timers (ELx physical timers vs ELx virtual timers).
So we introduce the common driver here but the actual SoC / architecture
/ board must provide the three helpers (arm_arch_timer_set_compare(),
arm_arch_timer_toggle(), arm_arch_timer_count()) using an header file
imported through the arch/cpu.h header file.
Signed-off-by: Carlo Caione <ccaione@baylibre.com>
Consistently place C++ use of extern "C" after all include directives,
within the negative branch of _ASMLANGUAGE if used.
The inclusion of the generated syscall files is placed outside the
extern "C" block as the generated file has its own extern "C" block.
Background from issue #17997:
Declarations that use C linkage should be placed within extern "C"
so the language linkage is correct when the header is included by
a C++ compiler.
Similarly #include directives should be outside the extern "C" to
ensure the language-specific default linkage is applied to any
declarations provided by the included header.
See: https://en.cppreference.com/w/cpp/language/language_linkage
Signed-off-by: Peter Bigot <peter.bigot@nordicsemi.no>
Move internal and architecture specific headers from include/drivers to
subfolder for timer:
include/drivers/timer
Signed-off-by: Anas Nashif <anas.nashif@intel.com>
