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| author | Pavel Tatashin <pasha.tatashin@oracle.com> | 2018-07-19 23:55:44 +0300 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2018-07-20 01:02:44 +0300 |
| commit | 03821f451d2d2d7599061244734245be139014ea (patch) | |
| tree | 6ba34ce72f69994e052c84adc2330b71006eaeee /arch/x86/kernel/tsc.c | |
| parent | 46457ea464f5341d1f9dad8dd213805d45f7f117 (diff) | |
| download | linux-03821f451d2d2d7599061244734245be139014ea.tar.xz | |
x86/tsc: Split native_calibrate_cpu() into early and late parts
During early boot TSC and CPU frequency can be calibrated using MSR, CPUID,
and quick PIT calibration methods. The other methods PIT/HPET/PMTIMER are
available only after ACPI is initialized.
Split native_calibrate_cpu() into early and late parts so they can be
called separately during early and late tsc calibration.
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: steven.sistare@oracle.com
Cc: daniel.m.jordan@oracle.com
Cc: linux@armlinux.org.uk
Cc: schwidefsky@de.ibm.com
Cc: heiko.carstens@de.ibm.com
Cc: john.stultz@linaro.org
Cc: sboyd@codeaurora.org
Cc: hpa@zytor.com
Cc: douly.fnst@cn.fujitsu.com
Cc: peterz@infradead.org
Cc: prarit@redhat.com
Cc: feng.tang@intel.com
Cc: pmladek@suse.com
Cc: gnomes@lxorguk.ukuu.org.uk
Cc: linux-s390@vger.kernel.org
Cc: boris.ostrovsky@oracle.com
Cc: jgross@suse.com
Cc: pbonzini@redhat.com
Link: https://lkml.kernel.org/r/20180719205545.16512-26-pasha.tatashin@oracle.com
Diffstat (limited to 'arch/x86/kernel/tsc.c')
| -rw-r--r-- | arch/x86/kernel/tsc.c | 54 |
1 files changed, 36 insertions, 18 deletions
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index 9277ae9b68b3..60586779b02c 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -680,30 +680,17 @@ static unsigned long cpu_khz_from_cpuid(void) return eax_base_mhz * 1000; } -/** - * native_calibrate_cpu - calibrate the cpu on boot +/* + * calibrate cpu using pit, hpet, and ptimer methods. They are available + * later in boot after acpi is initialized. */ -unsigned long native_calibrate_cpu(void) +static unsigned long pit_hpet_ptimer_calibrate_cpu(void) { u64 tsc1, tsc2, delta, ref1, ref2; unsigned long tsc_pit_min = ULONG_MAX, tsc_ref_min = ULONG_MAX; - unsigned long flags, latch, ms, fast_calibrate; + unsigned long flags, latch, ms; int hpet = is_hpet_enabled(), i, loopmin; - fast_calibrate = cpu_khz_from_cpuid(); - if (fast_calibrate) - return fast_calibrate; - - fast_calibrate = cpu_khz_from_msr(); - if (fast_calibrate) - return fast_calibrate; - - local_irq_save(flags); - fast_calibrate = quick_pit_calibrate(); - local_irq_restore(flags); - if (fast_calibrate) - return fast_calibrate; - /* * Run 5 calibration loops to get the lowest frequency value * (the best estimate). We use two different calibration modes @@ -846,6 +833,37 @@ unsigned long native_calibrate_cpu(void) return tsc_pit_min; } +/** + * native_calibrate_cpu_early - can calibrate the cpu early in boot + */ +unsigned long native_calibrate_cpu_early(void) +{ + unsigned long flags, fast_calibrate = cpu_khz_from_cpuid(); + + if (!fast_calibrate) + fast_calibrate = cpu_khz_from_msr(); + if (!fast_calibrate) { + local_irq_save(flags); + fast_calibrate = quick_pit_calibrate(); + local_irq_restore(flags); + } + return fast_calibrate; +} + + +/** + * native_calibrate_cpu - calibrate the cpu + */ +unsigned long native_calibrate_cpu(void) +{ + unsigned long tsc_freq = native_calibrate_cpu_early(); + + if (!tsc_freq) + tsc_freq = pit_hpet_ptimer_calibrate_cpu(); + + return tsc_freq; +} + void recalibrate_cpu_khz(void) { #ifndef CONFIG_SMP |