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Date: Fri, 22 Oct 2010 12:29:14 -0700
From: Alok Kataria <akataria@...are.com>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
the arch/x86 maintainers <x86@...nel.org>,
LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH 1/2] x86, apic: cleanup for APIC timer calibration hook
Preparatory change to add apic timer calibration hook.
From: Alok N Kataria <akataria@...are.com>
This change moves some APIC timer calibration code to a seperate function
to facilitate adding a apic clock calibration hook. This change has no
functional effect on the calibration routine.
Signed-off-by: Alok N Kataria <akataria@...are.com>
Index: linux-x86-tree.git/arch/x86/kernel/apic/apic.c
===================================================================
--- linux-x86-tree.git.orig/arch/x86/kernel/apic/apic.c 2010-10-21 13:55:08.000000000 -0700
+++ linux-x86-tree.git/arch/x86/kernel/apic/apic.c 2010-10-22 11:47:47.000000000 -0700
@@ -177,7 +177,7 @@ static struct resource lapic_resource =
.flags = IORESOURCE_MEM | IORESOURCE_BUSY,
};
-static unsigned int calibration_result;
+static unsigned int apic_calibration_res;
static int lapic_next_event(unsigned long delta,
struct clock_event_device *evt);
@@ -481,7 +481,7 @@ static void lapic_timer_setup(enum clock
switch (mode) {
case CLOCK_EVT_MODE_PERIODIC:
case CLOCK_EVT_MODE_ONESHOT:
- __setup_APIC_LVTT(calibration_result,
+ __setup_APIC_LVTT(apic_calibration_res,
mode != CLOCK_EVT_MODE_PERIODIC, 1);
break;
case CLOCK_EVT_MODE_UNUSED:
@@ -640,6 +640,43 @@ calibrate_by_pmtimer(long deltapm, long
return 0;
}
+int __init initialize_lapic_timer(long delta, unsigned int calibration_result)
+{
+ struct clock_event_device *levt = &__get_cpu_var(lapic_events);
+
+ /* Calculate the scaled math multiplication factor */
+ lapic_clockevent.mult = div_sc(delta, TICK_NSEC * LAPIC_CAL_LOOPS,
+ lapic_clockevent.shift);
+ lapic_clockevent.max_delta_ns =
+ clockevent_delta2ns(0x7FFFFF, &lapic_clockevent);
+ lapic_clockevent.min_delta_ns =
+ clockevent_delta2ns(0xF, &lapic_clockevent);
+
+ apic_calibration_res = calibration_result;
+
+ apic_printk(APIC_VERBOSE, "..... delta %ld\n", delta);
+ apic_printk(APIC_VERBOSE, "..... mult: %u\n", lapic_clockevent.mult);
+ apic_printk(APIC_VERBOSE, "..... calibration result: %u\n",
+ calibration_result);
+
+ apic_printk(APIC_VERBOSE, "..... host bus clock speed is "
+ "%u.%04u MHz.\n",
+ calibration_result / (1000000 / HZ),
+ calibration_result % (1000000 / HZ));
+
+ /*
+ * Do a sanity check on the APIC calibration result
+ */
+ if (calibration_result < (1000000 / HZ)) {
+ pr_warning("APIC frequency too slow, disabling apic timer\n");
+ return -1;
+ }
+
+ levt->features &= ~CLOCK_EVT_FEAT_DUMMY;
+ return 0;
+}
+
+/* Calibrates the APIC clock and initializes the local APIC timer */
static int __init calibrate_APIC_clock(void)
{
struct clock_event_device *levt = &__get_cpu_var(lapic_events);
@@ -647,6 +684,7 @@ static int __init calibrate_APIC_clock(v
unsigned long deltaj;
long delta, deltatsc;
int pm_referenced = 0;
+ unsigned int calibration_result;
local_irq_disable();
@@ -681,20 +719,12 @@ static int __init calibrate_APIC_clock(v
pm_referenced = !calibrate_by_pmtimer(lapic_cal_pm2 - lapic_cal_pm1,
&delta, &deltatsc);
- /* Calculate the scaled math multiplication factor */
- lapic_clockevent.mult = div_sc(delta, TICK_NSEC * LAPIC_CAL_LOOPS,
- 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 = (delta * APIC_DIVISOR) / LAPIC_CAL_LOOPS;
- apic_printk(APIC_VERBOSE, "..... delta %ld\n", delta);
- apic_printk(APIC_VERBOSE, "..... mult: %u\n", lapic_clockevent.mult);
- apic_printk(APIC_VERBOSE, "..... calibration result: %u\n",
- calibration_result);
+ if (initialize_lapic_timer(delta, calibration_result)) {
+ local_irq_enable();
+ return -1;
+ }
if (cpu_has_tsc) {
apic_printk(APIC_VERBOSE, "..... CPU clock speed is "
@@ -703,22 +733,6 @@ static int __init calibrate_APIC_clock(v
(deltatsc / LAPIC_CAL_LOOPS) % (1000000 / HZ));
}
- apic_printk(APIC_VERBOSE, "..... host bus clock speed is "
- "%u.%04u MHz.\n",
- calibration_result / (1000000 / HZ),
- calibration_result % (1000000 / HZ));
-
- /*
- * Do a sanity check on the APIC calibration result
- */
- if (calibration_result < (1000000 / HZ)) {
- local_irq_enable();
- pr_warning("APIC frequency too slow, disabling apic timer\n");
- return -1;
- }
-
- levt->features &= ~CLOCK_EVT_FEAT_DUMMY;
-
/*
* PM timer calibration failed or not turned on
* so lets try APIC timer based calibration
@@ -756,7 +770,7 @@ static int __init calibrate_APIC_clock(v
if (levt->features & CLOCK_EVT_FEAT_DUMMY) {
pr_warning("APIC timer disabled due to verification failure\n");
- return -1;
+ return -1;
}
return 0;
--
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