redonkable
/
alistair23-linux
1
0
Fork 0
Code Releases Activity

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
hifive-unleashed-5.1
Pavel Tatashin 2018-07-19 16:55:44 -04:00 committed by Thomas Gleixner
parent 46457ea464
commit 03821f451d
2 changed files with 37 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/x86/include/asm/tsc.h
View File

@ -40,6 +40,7 @@ extern int unsynchronized_tsc(void);
extern int check_tsc_unstable(void);
extern void mark_tsc_async_resets(char *reason);
extern unsigned long native_calibrate_cpu(void);
extern unsigned long native_calibrate_cpu_early(void);
extern unsigned long native_calibrate_tsc(void);
extern unsigned long long native_sched_clock_from_tsc(u64 tsc);

54
arch/x86/kernel/tsc.c
View File

@ -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