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x86_64: Consolidate tsc calibration

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Move the TSC calibration code to tsc.c. Reimplement it so the
pm timer can be used as a reference as well.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
This commit is contained in:
Thomas Gleixner
2007-10-12 23:04:06 +02:00
committed by Thomas Gleixner
parent 89b2bbd69b
commit d371698efd
4 changed files with 96 additions and 80 deletions
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33
arch/x86/kernel/time_64.c
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@@ -292,35 +292,6 @@ static unsigned int __init tsc_calibrate_cpu_khz(void)
return pmc_now * tsc_khz / (tsc_now - tsc_start);
}
/*
* pit_calibrate_tsc() uses the speaker output (channel 2) of
* the PIT. This is better than using the timer interrupt output,
* because we can read the value of the speaker with just one inb(),
* where we need three i/o operations for the interrupt channel.
* We count how many ticks the TSC does in 50 ms.
*/
static unsigned int __init pit_calibrate_tsc(void)
{
unsigned long start, end;
unsigned long flags;
spin_lock_irqsave(&i8253_lock, flags);
outb((inb(0x61) & ~0x02) | 0x01, 0x61);
outb(0xb0, 0x43);
outb((PIT_TICK_RATE / (1000 / 50)) & 0xff, 0x42);
outb((PIT_TICK_RATE / (1000 / 50)) >> 8, 0x42);
start = get_cycles_sync();
while ((inb(0x61) & 0x20) == 0);
end = get_cycles_sync();
spin_unlock_irqrestore(&i8253_lock, flags);
return (end - start) / 50;
}
#define PIT_MODE 0x43
#define PIT_CH0 0x40
@@ -376,14 +347,14 @@ void __init time_init(void)
if (hpet_use_timer) {
/* set tick_nsec to use the proper rate for HPET */
tick_nsec = TICK_NSEC_HPET;
tsc_khz = hpet_calibrate_tsc();
timename = "HPET";
} else {
pit_init();
tsc_khz = pit_calibrate_tsc();
timename = "PIT";
}
tsc_calibrate();
cpu_khz = tsc_khz;
if (cpu_has(&boot_cpu_data, X86_FEATURE_CONSTANT_TSC) &&
boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&