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CRIS: GENERIC_TIME fixes

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GENERIC_TIME was not functional for CRIS, giving random backward
time jumps.

For CRISv32 implement a new clocksource using the free running counter
and ditch the arch_gettimeoffset.

The random time jumps still existed, but turned out to be the write_seqlock
which was missing around our do_timer() call.

So switch over to GENERIC_TIME using the clocksource for CRISv32.

CRISv10 doesn't have the free running counter needed for the
clocksource trick, but we can still use GENERIC_TIME with
arch_gettimeoffset.

Unfortunately, there were problems in using the prescaler register
to timer0 for the gettimeoffset calculation, so it is now ignored,
making our resolution worse by the tune of 40usec (0.4%) worst case.

At the same time, clean up some formatting and use NSEC_PER_SEC
instead of 1000000000.

Signed-off-by: Jesper Nilsson <jesper.nilsson@axis.com>
This commit is contained in:
Jesper Nilsson
2010-07-30 17:33:07 +02:00
parent 26bfeea38a
commit 60dbd66331
4 changed files with 45 additions and 106 deletions
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7
arch/cris/kernel/time.c
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@@ -39,13 +39,16 @@ int have_rtc; /* used to remember if we have an RTC or not */;
extern unsigned long loops_per_jiffy; /* init/main.c */
unsigned long loops_per_usec;
#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
extern unsigned long do_slow_gettimeoffset(void);
static unsigned long (*do_gettimeoffset)(void) = do_slow_gettimeoffset;
u32 arch_gettimeoffset(void)
{
return do_gettimeoffset() * 1000;
return do_gettimeoffset() * 1000;
}
#endif
/*
* BUG: This routine does not handle hour overflow properly; it just
@@ -151,7 +154,7 @@ cris_do_profile(struct pt_regs* regs)
unsigned long long sched_clock(void)
{
return (unsigned long long)jiffies * (1000000000 / HZ) +
return (unsigned long long)jiffies * (NSEC_PER_SEC / HZ) +
get_ns_in_jiffie();
}