Update AT91SAM9/CAP9 PIT driver to use generic time and clockevent
infrastructure:
- Clocksource gives sub-microsecond timestamp precision, assuming
memory is clocked at over 16 MHz. It's less than a 32 bit counter,
unless it's is also generating IRQs.
- Clockevent device supports periodic mode only; no oneshot
support from this hardware. No IRQs generated unless it's the
active clocksource.
Later, another timer (probably from a TC module) can provide a oneshot
clockevent device to get NO_HZ and High-Res-Timer behavior.
This also updates the timekeeping to use the actual master clock rate
on the system, instead of compile-time <asm/arch/timex.h> constants
matching what Atmel's EK boards use. (Product boards may well differ!)
Plus cleanup: rename "*_timer*" symbols to "*_pit*" (there are other
timers, but only one PIT); shorter lines; remove needless CPP stuff;
make several symbols static; etc.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Victor <linux@maxim.org.za>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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