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Revert "clocksource: Provide a generic mult/shift factor calculation"

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This reverts commit cfc80b6829.
This commit is contained in:
黄涛 2011-07-30 15:56:49 +08:00
parent ab47eea0bb
commit 2448a5573a
3 changed files with 0 additions and 70 deletions
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7
include/linux/clockchips.h
View File

@ -130,13 +130,6 @@ extern int clockevents_program_event(struct clock_event_device *dev,
extern void clockevents_handle_noop(struct clock_event_device *dev);
static inline void
clockevents_calc_mult_shift(struct clock_event_device *ce, u32 freq, u32 minsec)
{
return clocks_calc_mult_shift(&ce->mult, &ce->shift, NSEC_PER_SEC,
freq, minsec);
}
#ifdef CONFIG_GENERIC_CLOCKEVENTS
extern void clockevents_notify(unsigned long reason, void *arg);
#else

10
include/linux/clocksource.h
View File

@ -281,16 +281,6 @@ extern void clocksource_resume(void);
extern struct clocksource * __init __weak clocksource_default_clock(void);
extern void clocksource_mark_unstable(struct clocksource *cs);
extern void
clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec);
static inline void
clocksource_calc_mult_shift(struct clocksource *cs, u32 freq, u32 minsec)
{
return clocks_calc_mult_shift(&cs->mult, &cs->shift, freq,
NSEC_PER_SEC, minsec);
}
#ifdef CONFIG_GENERIC_TIME_VSYSCALL
extern void
update_vsyscall(struct timespec *ts, struct clocksource *c, u32 mult);

53
kernel/time/clocksource.c
View File

@ -107,59 +107,6 @@ u64 timecounter_cyc2time(struct timecounter *tc,
}
EXPORT_SYMBOL(timecounter_cyc2time);
/**
* clocks_calc_mult_shift - calculate mult/shift factors for scaled math of clocks
* @mult: pointer to mult variable
* @shift: pointer to shift variable
* @from: frequency to convert from
* @to: frequency to convert to
* @minsec: guaranteed runtime conversion range in seconds
*
* The function evaluates the shift/mult pair for the scaled math
* operations of clocksources and clockevents.
*
* @to and @from are frequency values in HZ. For clock sources @to is
* NSEC_PER_SEC == 1GHz and @from is the counter frequency. For clock
* event @to is the counter frequency and @from is NSEC_PER_SEC.
*
* The @minsec conversion range argument controls the time frame in
* seconds which must be covered by the runtime conversion with the
* calculated mult and shift factors. This guarantees that no 64bit
* overflow happens when the input value of the conversion is
* multiplied with the calculated mult factor. Larger ranges may
* reduce the conversion accuracy by chosing smaller mult and shift
* factors.
*/
void
clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec)
{
u64 tmp;
u32 sft, sftacc= 32;
/*
* Calculate the shift factor which is limiting the conversion
* range:
*/
tmp = ((u64)minsec * from) >> 32;
while (tmp) {
tmp >>=1;
sftacc--;
}
/*
* Find the conversion shift/mult pair which has the best
* accuracy and fits the maxsec conversion range:
*/
for (sft = 32; sft > 0; sft--) {
tmp = (u64) to << sft;
do_div(tmp, from);
if ((tmp >> sftacc) == 0)
break;
}
*mult = tmp;
*shift = sft;
}
/*[Clocksource internal variables]---------
* curr_clocksource:
* currently selected clocksource.