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x86: TSC: separate hpet/pmtimer calculation out 

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Thomas Gleixner 2008-09-04 15:18:48 +00:00 committed by Ingo Molnar
parent cce3e05724
commit d683ef7afe
1 changed files with 41 additions and 15 deletions
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56
arch/x86/kernel/tsc.c
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@ -122,6 +122,43 @@ static u64 tsc_read_refs(u64 *pm, u64 *hpet)
return ULLONG_MAX;
}
/*
* Calculate the TSC frequency from HPET reference
*/
static unsigned long calc_hpet_ref(u64 deltatsc, u64 hpet1, u64 hpet2)
{
u64 tmp;
if (hpet2 < hpet1)
hpet2 += 0x100000000ULL;
hpet2 -= hpet1;
tmp = ((u64)hpet2 * hpet_readl(HPET_PERIOD));
do_div(tmp, 1000000);
do_div(deltatsc, tmp);
return (unsigned long) deltatsc;
}
/*
* Calculate the TSC frequency from PMTimer reference
*/
static unsigned long calc_pmtimer_ref(u64 deltatsc, u64 pm1, u64 pm2)
{
u64 tmp;
if (!pm1 && !pm2)
return ULONG_MAX;
if (pm2 < pm1)
pm2 += (u64)ACPI_PM_OVRRUN;
pm2 -= pm1;
tmp = pm2 * 1000000000LL;
do_div(tmp, PMTMR_TICKS_PER_SEC);
do_div(deltatsc, tmp);
return (unsigned long) deltatsc;
}
#define CAL_MS 50
#define CAL_LATCH (CLOCK_TICK_RATE / (1000 / CAL_MS))
#define CAL_PIT_LOOPS 5000
@ -247,22 +284,11 @@ unsigned long native_calibrate_tsc(void)
continue;
tsc2 = (tsc2 - tsc1) * 1000000LL;
if (hpet)
tsc2 = calc_hpet_ref(tsc2, hpet1, hpet2);
else
tsc2 = calc_pmtimer_ref(tsc2, pm1, pm2);
if (hpet) {
if (hpet2 < hpet1)
hpet2 += 0x100000000ULL;
hpet2 -= hpet1;
tsc1 = ((u64)hpet2 * hpet_readl(HPET_PERIOD));
do_div(tsc1, 1000000);
} else {
if (pm2 < pm1)
pm2 += (u64)ACPI_PM_OVRRUN;
pm2 -= pm1;
tsc1 = pm2 * 1000000000LL;
do_div(tsc1, PMTMR_TICKS_PER_SEC);
}
do_div(tsc2, tsc1);
tsc_ref_min = min(tsc_ref_min, (unsigned long) tsc2);
}