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authorLaurent Vivier2015-08-24 19:29:45 +0200
committerLaurent Vivier2015-09-25 14:53:29 +0200
commit37b9ab92f7f8295c61daa4a8893eb8fb1add63e2 (patch)
tree92c9a4c83231fdd65ae066f4571fcd9e1cba2ce2 /include/hw/timer/allwinner-a10-pit.h
parenti6300esb: remove muldiv64() (diff)
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rtl8139: remove muldiv64()
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(), PCI_FREQUENCY) 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 PCI frequency is 33 MHz, we can also do: y = x * 30; /* 33 MHz PCI period is 30 ns */ Which is much more simple. This implies a 33.333333 MHz PCI frequency, but this is correct. Signed-off-by: Laurent Vivier <lvivier@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
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