| #ifndef _ASMi386_TIMER_H |
| #define _ASMi386_TIMER_H |
| #include <linux/init.h> |
| #include <linux/pm.h> |
| |
| #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 |
