projects / deliverable / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| 1965aae3 PA |
1 | #ifndef _ASM_X86_TIMER_H |
| 2 | #define _ASM_X86_TIMER_H | |
| 1da177e4 | 3 | #include <linux/init.h> |
| c3c433e4 | 4 | #include <linux/pm.h> |
| 53d517cd | 5 | #include <linux/percpu.h> |
| 8e6dafd6 | 6 | #include <linux/interrupt.h> |
| 1da177e4 | 7 | |
| 1da177e4 | 8 | #define TICK_SIZE (tick_nsec / 1000) |
| 6cb9a835 | 9 | |
| 6cb9a835 | 10 | unsigned long long native_sched_clock(void); |
| 64fcbac1 | 11 | extern int recalibrate_cpu_khz(void); |
| 6cb9a835 | 12 | |
| 64fcbac1 | 13 | #if defined(CONFIG_X86_32) && defined(CONFIG_X86_IO_APIC) |
| 1da177e4 | 14 | extern int timer_ack; |
| 64fcbac1 TG |
15 | #else |
| 16 | # define timer_ack (0) | |
| 845b3944 | 17 | #endif |
| cc038491 JS |
18 | |
| 19 | extern int no_timer_check; | |
| 1da177e4 | 20 | |
| 53d517cd | 21 | /* Accelerators for sched_clock() |
| 688340ea JF |
22 | * convert from cycles(64bits) => nanoseconds (64bits) |
| 23 | * basic equation: | |
| 24 | * ns = cycles / (freq / ns_per_sec) | |
| 25 | * ns = cycles * (ns_per_sec / freq) | |
| 26 | * ns = cycles * (10^9 / (cpu_khz * 10^3)) | |
| 27 | * ns = cycles * (10^6 / cpu_khz) | |
| 28 | * | |
| 29 | * Then we use scaling math (suggested by george@mvista.com) to get: | |
| 30 | * ns = cycles * (10^6 * SC / cpu_khz) / SC | |
| 31 | * ns = cycles * cyc2ns_scale / SC | |
| 32 | * | |
| 33 | * And since SC is a constant power of two, we can convert the div | |
| 34 | * into a shift. | |
| 35 | * | |
| 53d517cd | 36 | * We can use khz divisor instead of mhz to keep a better precision, since |
| 688340ea JF |
37 | * cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits. |
| 38 | * (mathieu.desnoyers@polymtl.ca) | |
| 39 | * | |
| 40 | * -johnstul@us.ibm.com "math is hard, lets go shopping!" | |
| 41 | */ | |
| 53d517cd GC |
42 | |
| 43 | DECLARE_PER_CPU(unsigned long, cyc2ns); | |
| 84599f8a | 44 | DECLARE_PER_CPU(unsigned long long, cyc2ns_offset); |
| 688340ea JF |
45 | |
| 46 | #define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */ | |
| 47 | ||
| 53d517cd | 48 | static inline unsigned long long __cycles_2_ns(unsigned long long cyc) |
| 688340ea | 49 | { |
| 84599f8a PZ |
50 | int cpu = smp_processor_id(); |
| 51 | unsigned long long ns = per_cpu(cyc2ns_offset, cpu); | |
| 52 | ns += cyc * per_cpu(cyc2ns, cpu) >> CYC2NS_SCALE_FACTOR; | |
| 53 | return ns; | |
| 688340ea JF |
54 | } |
| 55 | ||
| 53d517cd GC |
56 | static inline unsigned long long cycles_2_ns(unsigned long long cyc) |
| 57 | { | |
| 58 | unsigned long long ns; | |
| 59 | unsigned long flags; | |
| 60 | ||
| 61 | local_irq_save(flags); | |
| 62 | ns = __cycles_2_ns(cyc); | |
| 63 | local_irq_restore(flags); | |
| 64 | ||
| 65 | return ns; | |
| 66 | } | |
| 688340ea | 67 | |
| 1965aae3 | 68 | #endif /* _ASM_X86_TIMER_H */ |