Commit-ID: 03821f451d2d2d7599061244734245be139014ea Gitweb: https://git.kernel.org/tip/03821f451d2d2d7599061244734245be139014ea Author: Pavel Tatashin <[email protected]> AuthorDate: Thu, 19 Jul 2018 16:55:44 -0400 Committer: Thomas Gleixner <[email protected]> CommitDate: Fri, 20 Jul 2018 00:02:44 +0200
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 <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Link: https://lkml.kernel.org/r/[email protected] --- arch/x86/include/asm/tsc.h | 1 + arch/x86/kernel/tsc.c | 54 ++++++++++++++++++++++++++++++---------------- 2 files changed, 37 insertions(+), 18 deletions(-) diff --git a/arch/x86/include/asm/tsc.h b/arch/x86/include/asm/tsc.h index c4368ff73652..88140e4f2292 100644 --- a/arch/x86/include/asm/tsc.h +++ b/arch/x86/include/asm/tsc.h @@ -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); 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
