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Subject[patch-mm 14/33] x86_64: Consolidate tsc calibration
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>

---
arch/x86_64/kernel/hpet.c | 49 -------------------------
arch/x86_64/kernel/time.c | 33 +---------------
arch/x86_64/kernel/tsc.c | 90 ++++++++++++++++++++++++++++++++++++++++++++++
include/asm-i386/tsc.h | 4 ++
4 files changed, 96 insertions(+), 80 deletions(-)

Index: linux-2.6.22-rc6-mm/arch/x86_64/kernel/hpet.c
===================================================================
--- linux-2.6.22-rc6-mm.orig/arch/x86_64/kernel/hpet.c 2007-07-15 17:33:08.000000000 +0200
+++ linux-2.6.22-rc6-mm/arch/x86_64/kernel/hpet.c 2007-07-15 17:48:53.000000000 +0200
@@ -184,55 +184,6 @@ int hpet_reenable(void)
return hpet_timer_stop_set_go(hpet_tick);
}

-/*
- * calibrate_tsc() calibrates the processor TSC in a very simple way, comparing
- * it to the HPET timer of known frequency.
- */
-
-#define TICK_COUNT 100000000
-#define SMI_THRESHOLD 50000
-#define MAX_TRIES 5
-
-/*
- * Some platforms take periodic SMI interrupts with 5ms duration. Make sure none
- * occurs between the reads of the hpet & TSC.
- */
-static void __init read_hpet_tsc(int *hpet, int *tsc)
-{
- int tsc1, tsc2, hpet1, i;
-
- for (i = 0; i < MAX_TRIES; i++) {
- tsc1 = get_cycles_sync();
- hpet1 = hpet_readl(HPET_COUNTER);
- tsc2 = get_cycles_sync();
- if ((tsc2 - tsc1) < SMI_THRESHOLD)
- break;
- }
- *hpet = hpet1;
- *tsc = tsc2;
-}
-
-unsigned int __init hpet_calibrate_tsc(void)
-{
- int tsc_start, hpet_start;
- int tsc_now, hpet_now;
- unsigned long flags;
-
- local_irq_save(flags);
-
- read_hpet_tsc(&hpet_start, &tsc_start);
-
- do {
- local_irq_disable();
- read_hpet_tsc(&hpet_now, &tsc_now);
- local_irq_restore(flags);
- } while ((tsc_now - tsc_start) < TICK_COUNT &&
- (hpet_now - hpet_start) < TICK_COUNT);
-
- return (tsc_now - tsc_start) * 1000000000L
- / ((hpet_now - hpet_start) * hpet_period / 1000);
-}
-
#ifdef CONFIG_HPET_EMULATE_RTC
/* HPET in LegacyReplacement Mode eats up RTC interrupt line. When, HPET
* is enabled, we support RTC interrupt functionality in software.
Index: linux-2.6.22-rc6-mm/arch/x86_64/kernel/time.c
===================================================================
--- linux-2.6.22-rc6-mm.orig/arch/x86_64/kernel/time.c 2007-07-15 17:34:06.000000000 +0200
+++ linux-2.6.22-rc6-mm/arch/x86_64/kernel/time.c 2007-07-15 17:49:00.000000000 +0200
@@ -292,35 +292,6 @@ static unsigned int __init tsc_calibrate
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 &&
Index: linux-2.6.22-rc6-mm/arch/x86_64/kernel/tsc.c
===================================================================
--- linux-2.6.22-rc6-mm.orig/arch/x86_64/kernel/tsc.c 2007-07-15 17:31:15.000000000 +0200
+++ linux-2.6.22-rc6-mm/arch/x86_64/kernel/tsc.c 2007-07-15 17:34:42.000000000 +0200
@@ -6,7 +6,9 @@
#include <linux/time.h>
#include <linux/acpi.h>
#include <linux/cpufreq.h>
+#include <linux/acpi_pmtmr.h>

+#include <asm/hpet.h>
#include <asm/timex.h>

static int notsc __initdata = 0;
@@ -90,6 +92,94 @@ core_initcall(cpufreq_tsc);

#endif

+#define MAX_RETRIES 5
+#define SMI_TRESHOLD 50000
+
+/*
+ * Read TSC and the reference counters. Take care of SMI disturbance
+ */
+static unsigned long __init tsc_read_refs(unsigned long *pm,
+ unsigned long *hpet)
+{
+ unsigned long t1, t2;
+ int i;
+
+ for (i = 0; i < MAX_RETRIES; i++) {
+ t1 = get_cycles_sync();
+ if (hpet)
+ *hpet = hpet_readl(HPET_COUNTER) & 0xFFFFFFFF;
+ else
+ *pm = acpi_pm_read_early();
+ t2 = get_cycles_sync();
+ if ((t2 - t1) < SMI_TRESHOLD)
+ return t2;
+ }
+ return ULONG_MAX;
+}
+
+/**
+ * tsc_calibrate - calibrate the tsc on boot
+ */
+void __init tsc_calibrate(void)
+{
+ unsigned long flags, tsc1, tsc2, tr1, tr2, pm1, pm2, hpet1, hpet2;
+ int hpet = is_hpet_enabled();
+
+ local_irq_save(flags);
+
+ tsc1 = tsc_read_refs(&pm1, hpet ? &hpet1 : NULL);
+
+ outb((inb(0x61) & ~0x02) | 0x01, 0x61);
+
+ outb(0xb0, 0x43);
+ outb((CLOCK_TICK_RATE / (1000 / 50)) & 0xff, 0x42);
+ outb((CLOCK_TICK_RATE / (1000 / 50)) >> 8, 0x42);
+ tr1 = get_cycles_sync();
+ while ((inb(0x61) & 0x20) == 0);
+ tr2 = get_cycles_sync();
+
+ tsc2 = tsc_read_refs(&pm2, hpet ? &hpet2 : NULL);
+
+ local_irq_restore(flags);
+
+ /*
+ * Preset the result with the raw and inaccurate PIT
+ * calibration value
+ */
+ tsc_khz = (tr2 - tr1) / 50;
+
+ /* hpet or pmtimer available ? */
+ if (!hpet && !pm1 && !pm2) {
+ printk(KERN_INFO "TSC calibrated against PIT\n");
+ return;
+ }
+
+ /* Check, whether the sampling was disturbed by an SMI */
+ if (tsc1 == ULONG_MAX || tsc2 == ULONG_MAX) {
+ printk(KERN_WARNING "TSC calibration disturbed by SMI, "
+ "using PIT calibration result\n");
+ return;
+ }
+
+ tsc2 = (tsc2 - tsc1) * 1000000L;
+
+ if (hpet) {
+ printk(KERN_INFO "TSC calibrated against HPET\n");
+ if (hpet2 < hpet1)
+ hpet2 += 0x100000000;
+ hpet2 -= hpet1;
+ tsc1 = (hpet2 * hpet_readl(HPET_PERIOD)) / 1000000;
+ } else {
+ printk(KERN_INFO "TSC calibrated against PM_TIMER\n");
+ if (pm2 < pm1)
+ pm2 += ACPI_PM_OVRRUN;
+ pm2 -= pm1;
+ tsc1 = (pm2 * 1000000000) / PMTMR_TICKS_PER_SEC;
+ }
+
+ tsc_khz = tsc2 / tsc1;
+}
+
/*
* Make an educated guess if the TSC is trustworthy and synchronized
* over all CPUs.
Index: linux-2.6.22-rc6-mm/include/asm-i386/tsc.h
===================================================================
--- linux-2.6.22-rc6-mm.orig/include/asm-i386/tsc.h 2007-07-15 17:26:45.000000000 +0200
+++ linux-2.6.22-rc6-mm/include/asm-i386/tsc.h 2007-07-15 17:34:42.000000000 +0200
@@ -71,4 +71,8 @@ extern void init_tsc_clocksource(void);
extern void check_tsc_sync_source(int cpu);
extern void check_tsc_sync_target(void);

+#ifdef CONFIG_X86_64
+extern void tsc_calibrate(void);
+#endif
+
#endif
--

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