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Date: Sun, 24 Aug 2008 22:41:26 -0700
From: Yinghai Lu <yhlu.kernel@...il.com>
To: Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
"H. Peter Anvin" <hpa@...or.com>,
Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org, Yinghai Lu <yhlu.kernel@...il.com>
Subject: [PATCH] x86: let 64 bit to use 32 bit calibrate_apic_clock
Signed-of-by: Yinghai Lu <yhlu.kernel@...il.com>
---
arch/x86/kernel/apic.c | 92 ++-----------------------------------------------
1 file changed, 5 insertions(+), 87 deletions(-)
Index: linux-2.6/arch/x86/kernel/apic.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/apic.c
+++ linux-2.6/arch/x86/kernel/apic.c
@@ -478,90 +478,6 @@ static void __cpuinit setup_APIC_timer(v
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(v
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(v
}
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(v
return 0;
}
-#endif
-
/*
* Setup the boot APIC
*
--
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