Linux Kernel  3.7.1
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tsc.h
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1 /*
2  * x86 TSC related functions
3  */
4 #ifndef _ASM_X86_TSC_H
5 #define _ASM_X86_TSC_H
6 
7 #include <asm/processor.h>
8 
9 #define NS_SCALE 10 /* 2^10, carefully chosen */
10 #define US_SCALE 32 /* 2^32, arbitralrily chosen */
11 
12 /*
13  * Standard way to access the cycle counter.
14  */
15 typedef unsigned long long cycles_t;
16 
17 extern unsigned int cpu_khz;
18 extern unsigned int tsc_khz;
19 
20 extern void disable_TSC(void);
21 
22 static inline cycles_t get_cycles(void)
23 {
24  unsigned long long ret = 0;
25 
26 #ifndef CONFIG_X86_TSC
27  if (!cpu_has_tsc)
28  return 0;
29 #endif
30  rdtscll(ret);
31 
32  return ret;
33 }
34 
35 static __always_inline cycles_t vget_cycles(void)
36 {
37  /*
38  * We only do VDSOs on TSC capable CPUs, so this shouldn't
39  * access boot_cpu_data (which is not VDSO-safe):
40  */
41 #ifndef CONFIG_X86_TSC
42  if (!cpu_has_tsc)
43  return 0;
44 #endif
45  return (cycles_t)__native_read_tsc();
46 }
47 
48 extern void tsc_init(void);
49 extern void mark_tsc_unstable(char *reason);
50 extern int unsynchronized_tsc(void);
51 extern int check_tsc_unstable(void);
52 extern unsigned long native_calibrate_tsc(void);
53 
54 extern int tsc_clocksource_reliable;
55 
56 /*
57  * Boot-time check whether the TSCs are synchronized across
58  * all CPUs/cores:
59  */
60 extern void check_tsc_sync_source(int cpu);
61 extern void check_tsc_sync_target(void);
62 
63 extern int notsc_setup(char *);
64 extern void tsc_save_sched_clock_state(void);
65 extern void tsc_restore_sched_clock_state(void);
66 
67 #endif /* _ASM_X86_TSC_H */