683dca6bd5
Originally, timers were ticks based, and it made sense to
add ticks to current time to know when to trigger an alarm.
But since commit:
7447545 change all other clock references to use nanosecond resolution accessors
All timers use nanoseconds and we need to convert ticks to nanoseconds, by
doing something like:
y = muldiv64(x, get_ticks_per_sec(), TIMER_FREQ)
where x is the number of device ticks and y the number of system ticks.
y is used as nanoseconds in timer functions,
it works because 1 tick is 1 nanosecond.
(get_ticks_per_sec() is 10^9)
But as MIPS timer frequency is 100 MHz, we can also do:
y = x * 10; /* 100 MHz period is 10 ns */
Signed-off-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: Leon Alrae <leon.alrae@imgtec.com>
Read the documentation in qemu-doc.html or on http://wiki.qemu-project.org - QEMU team