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Commit d683ef7a authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Ingo Molnar
Browse files

x86: TSC: separate hpet/pmtimer calculation out 



Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent cce3e057

arch/x86/kernel/tsc.c

+41 −15
Original line number Diff line number Diff line
@@ -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);

	}