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 
get_cycles(void)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 
vget_cycles(void)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 /*
55  * Boot-time check whether the TSCs are synchronized across
56  * all CPUs/cores:
57  */
58 extern void check_tsc_sync_source(int cpu);
59 extern void check_tsc_sync_target(void);
60 
61 extern int notsc_setup(char *);
62 extern void save_sched_clock_state(void);
63 extern void restore_sched_clock_state(void);
64 
65 #endif /* _ASM_X86_TSC_H */
66