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x86: let 64 bit to use 32 bit calibrate_apic_clock

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Use the 32-bit APIC calibration code - it's more mature.

Signed-of-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Yinghai Lu 2008-08-24 22:41:26 -07:00 committed by Ingo Molnar
parent 0f611ffaea
commit e492c5ae85
1 changed files with 2 additions and 86 deletions
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88
arch/x86/kernel/apic.c
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@ -478,90 +478,6 @@ static void __cpuinit setup_APIC_timer(void)
clockevents_register_device(levt);
}
#ifdef CONFIG_X86_64
/*
* In this function we calibrate APIC bus clocks to the external
* timer. Unfortunately we cannot use jiffies and the timer irq
* to calibrate, since some later bootup code depends on getting
* the first irq? Ugh.
*
* We want to do the calibration only once since we
* want to have local timer irqs syncron. CPUs connected
* by the same APIC bus have the very same bus frequency.
* And we want to have irqs off anyways, no accidental
* APIC irq that way.
*/
#define TICK_COUNT 100000000
static int __init calibrate_APIC_clock(void)
{
unsigned apic, apic_start;
unsigned long tsc, tsc_start;
int result;
local_irq_disable();
/*
* Put whatever arbitrary (but long enough) timeout
* value into the APIC clock, we just want to get the
* counter running for calibration.
*
* No interrupt enable !
*/
__setup_APIC_LVTT(250000000, 0, 0);
apic_start = apic_read(APIC_TMCCT);
#ifdef CONFIG_X86_PM_TIMER
if (apic_calibrate_pmtmr && pmtmr_ioport) {
pmtimer_wait(5000); /* 5ms wait */
apic = apic_read(APIC_TMCCT);
result = (apic_start - apic) * 1000L / 5;
} else
#endif
{
rdtscll(tsc_start);
do {
apic = apic_read(APIC_TMCCT);
rdtscll(tsc);
} while ((tsc - tsc_start) < TICK_COUNT &&
(apic_start - apic) < TICK_COUNT);
result = (apic_start - apic) * 1000L * tsc_khz /
(tsc - tsc_start);
}
local_irq_enable();
printk(KERN_DEBUG "APIC timer calibration result %d\n", result);
printk(KERN_INFO "Detected %d.%03d MHz APIC timer.\n",
result / 1000 / 1000, result / 1000 % 1000);
/* Calculate the scaled math multiplication factor */
lapic_clockevent.mult = div_sc(result, NSEC_PER_SEC,
lapic_clockevent.shift);
lapic_clockevent.max_delta_ns =
clockevent_delta2ns(0x7FFFFF, &lapic_clockevent);
lapic_clockevent.min_delta_ns =
clockevent_delta2ns(0xF, &lapic_clockevent);
calibration_result = (result * APIC_DIVISOR) / HZ;
/*
* Do a sanity check on the APIC calibration result
*/
if (calibration_result < (1000000 / HZ)) {
printk(KERN_WARNING
"APIC frequency too slow, disabling apic timer\n");
return -1;
}
return 0;
}
#else
/*
* In this functions we calibrate APIC bus clocks to the external timer.
*
@ -659,6 +575,7 @@ static int __init calibrate_APIC_clock(void)
delta = lapic_cal_t1 - lapic_cal_t2;
apic_printk(APIC_VERBOSE, "... lapic delta = %ld\n", delta);
#ifdef CONFIG_X86_PM_TIMER
/* Check, if the PM timer is available */
deltapm = lapic_cal_pm2 - lapic_cal_pm1;
apic_printk(APIC_VERBOSE, "... PM timer delta = %ld\n", deltapm);
@ -687,6 +604,7 @@ static int __init calibrate_APIC_clock(void)
}
pm_referenced = 1;
}
#endif
/* Calculate the scaled math multiplication factor */
lapic_clockevent.mult = div_sc(delta, TICK_NSEC * LAPIC_CAL_LOOPS,
@ -773,8 +691,6 @@ static int __init calibrate_APIC_clock(void)
return 0;
}
#endif
/*
* Setup the boot APIC
*