From 96a388de5dc53a8b234b3fd41f3ae2cedc9ffd42 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 11 Oct 2007 11:20:03 +0200 Subject: i386/x86_64: move headers to include/asm-x86 Move the headers to include/asm-x86 and fixup the header install make rules Signed-off-by: Thomas Gleixner Signed-off-by: Ingo Molnar --- include/asm-x86/timer.h | 50 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) create mode 100644 include/asm-x86/timer.h (limited to 'include/asm-x86/timer.h') diff --git a/include/asm-x86/timer.h b/include/asm-x86/timer.h new file mode 100644 index 00000000000..0db7e994fb8 --- /dev/null +++ b/include/asm-x86/timer.h @@ -0,0 +1,50 @@ +#ifndef _ASMi386_TIMER_H +#define _ASMi386_TIMER_H +#include +#include + +#define TICK_SIZE (tick_nsec / 1000) + +unsigned long long native_sched_clock(void); +unsigned long native_calculate_cpu_khz(void); + +extern int timer_ack; +extern int no_timer_check; +extern int recalibrate_cpu_khz(void); + +#ifndef CONFIG_PARAVIRT +#define calculate_cpu_khz() native_calculate_cpu_khz() +#endif + +/* Accellerators for sched_clock() + * convert from cycles(64bits) => nanoseconds (64bits) + * basic equation: + * ns = cycles / (freq / ns_per_sec) + * ns = cycles * (ns_per_sec / freq) + * ns = cycles * (10^9 / (cpu_khz * 10^3)) + * ns = cycles * (10^6 / cpu_khz) + * + * Then we use scaling math (suggested by george@mvista.com) to get: + * ns = cycles * (10^6 * SC / cpu_khz) / SC + * ns = cycles * cyc2ns_scale / SC + * + * And since SC is a constant power of two, we can convert the div + * into a shift. + * + * We can use khz divisor instead of mhz to keep a better percision, since + * cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits. + * (mathieu.desnoyers@polymtl.ca) + * + * -johnstul@us.ibm.com "math is hard, lets go shopping!" + */ +extern unsigned long cyc2ns_scale __read_mostly; + +#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */ + +static inline unsigned long long cycles_2_ns(unsigned long long cyc) +{ + return (cyc * cyc2ns_scale) >> CYC2NS_SCALE_FACTOR; +} + + +#endif -- cgit v1.2.3