lkml.org 
[lkml]   [2008]   [Sep]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[RFC patch 2/4] x86: TSC: separate hpet/pmtimer calculation out
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
arch/x86/kernel/tsc.c | 56 ++++++++++++++++++++++++++++++++++++--------------
1 file changed, 41 insertions(+), 15 deletions(-)
Index: linux-2.6/arch/x86/kernel/tsc.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/tsc.c
+++ linux-2.6/arch/x86/kernel/tsc.c
@@ -122,6 +122,43 @@ static u64 tsc_read_refs(u64 *pm, u64 *h
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);
}

--



\
 
 \ /
  Last update: 2008-09-04 17:23    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site