• Paul Mackerras's avatar
    [POWERPC] Make clockevents work on PPC601 processors · cdec12ae
    Paul Mackerras authored
    In testing the new clocksource and clockevent code on a PPC601
    processor, I discovered that the clockevent multiplier value for the
    decrementer clockevent was overflowing.  Because the RTCL register in
    the 601 effectively counts at 1GHz (it doesn't actually, but it
    increases by 128 every 128ns), and the shift value was 32, that meant
    the multiplier value had to be 2^32, which won't fit in an unsigned
    long on 32-bit.  The same problem would arise on any platform where
    the timebase frequency was 1GHz or more (not that we actually have any
    such machines today).
    
    This fixes it by reducing the shift value to 16.  Doing the
    calculations with a resolution of 2^-16 nanoseconds (15 femtoseconds)
    should be quite adequate.  :)
    Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
    cdec12ae
time.c 30.1 KB