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>
6f36300219