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Linus Torvalds1da177e2005-04-16 15:20:36 -07001#ifndef _ASMi386_TIMER_H
2#define _ASMi386_TIMER_H
3#include <linux/init.h>
Shaohua Lic3c433e2005-09-03 15:57:07 -07004#include <linux/pm.h>
Guillaume Chazarain53d517c2008-01-30 13:30:06 +01005#include <linux/percpu.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -07006
Linus Torvalds1da177e2005-04-16 15:20:36 -07007#define TICK_SIZE (tick_nsec / 1000)
Zachary Amsden6cb9a832007-03-05 00:30:35 -08008
Zachary Amsden6cb9a832007-03-05 00:30:35 -08009unsigned long long native_sched_clock(void);
Zachary Amsden1182d852007-03-05 00:30:36 -080010unsigned long native_calculate_cpu_khz(void);
Zachary Amsden6cb9a832007-03-05 00:30:35 -080011
Linus Torvalds1da177e2005-04-16 15:20:36 -070012extern int timer_ack;
Zachary Amsden7ce0bcf2007-02-13 13:26:21 +010013extern int no_timer_check;
Dave Jonesc5d28fb2005-05-31 19:03:46 -070014extern int recalibrate_cpu_khz(void);
Linus Torvalds1da177e2005-04-16 15:20:36 -070015
Zachary Amsden6cb9a832007-03-05 00:30:35 -080016#ifndef CONFIG_PARAVIRT
Zachary Amsden1182d852007-03-05 00:30:36 -080017#define calculate_cpu_khz() native_calculate_cpu_khz()
Zachary Amsden6cb9a832007-03-05 00:30:35 -080018#endif
19
Guillaume Chazarain53d517c2008-01-30 13:30:06 +010020/* Accelerators for sched_clock()
Jeremy Fitzhardinge688340e2007-07-17 18:37:04 -070021 * convert from cycles(64bits) => nanoseconds (64bits)
22 * basic equation:
23 * ns = cycles / (freq / ns_per_sec)
24 * ns = cycles * (ns_per_sec / freq)
25 * ns = cycles * (10^9 / (cpu_khz * 10^3))
26 * ns = cycles * (10^6 / cpu_khz)
27 *
28 * Then we use scaling math (suggested by george@mvista.com) to get:
29 * ns = cycles * (10^6 * SC / cpu_khz) / SC
30 * ns = cycles * cyc2ns_scale / SC
31 *
32 * And since SC is a constant power of two, we can convert the div
33 * into a shift.
34 *
Guillaume Chazarain53d517c2008-01-30 13:30:06 +010035 * We can use khz divisor instead of mhz to keep a better precision, since
Jeremy Fitzhardinge688340e2007-07-17 18:37:04 -070036 * cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits.
37 * (mathieu.desnoyers@polymtl.ca)
38 *
39 * -johnstul@us.ibm.com "math is hard, lets go shopping!"
40 */
Guillaume Chazarain53d517c2008-01-30 13:30:06 +010041
42DECLARE_PER_CPU(unsigned long, cyc2ns);
Jeremy Fitzhardinge688340e2007-07-17 18:37:04 -070043
44#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
45
Guillaume Chazarain53d517c2008-01-30 13:30:06 +010046static inline unsigned long long __cycles_2_ns(unsigned long long cyc)
Jeremy Fitzhardinge688340e2007-07-17 18:37:04 -070047{
Guillaume Chazarain53d517c2008-01-30 13:30:06 +010048 return cyc * per_cpu(cyc2ns, smp_processor_id()) >> CYC2NS_SCALE_FACTOR;
Jeremy Fitzhardinge688340e2007-07-17 18:37:04 -070049}
50
Guillaume Chazarain53d517c2008-01-30 13:30:06 +010051static inline unsigned long long cycles_2_ns(unsigned long long cyc)
52{
53 unsigned long long ns;
54 unsigned long flags;
55
56 local_irq_save(flags);
57 ns = __cycles_2_ns(cyc);
58 local_irq_restore(flags);
59
60 return ns;
61}
Jeremy Fitzhardinge688340e2007-07-17 18:37:04 -070062
Linus Torvalds1da177e2005-04-16 15:20:36 -070063#endif