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 */
15typedef unsigned long long cycles_t;
16
17extern unsigned int cpu_khz;
18extern unsigned int tsc_khz;
19
20static inline cycles_t get_cycles(void)
21{
22	unsigned long long ret = 0;
23
24#ifndef CONFIG_X86_TSC
25	if (!cpu_has_tsc)
26		return 0;
27#endif
28
29#if defined(CONFIG_X86_GENERIC) || defined(CONFIG_X86_TSC)
30	rdtscll(ret);
31#endif
32	return ret;
33}
34
35/* Like get_cycles, but make sure the CPU is synchronized. */
36static __always_inline cycles_t get_cycles_sync(void)
37{
38	unsigned long long ret;
39	unsigned eax, edx;
40
41	/*
42  	 * Use RDTSCP if possible; it is guaranteed to be synchronous
43 	 * and doesn't cause a VMEXIT on Hypervisors
44	 */
45	alternative_io(ASM_NOP3, ".byte 0x0f,0x01,0xf9", X86_FEATURE_RDTSCP,
46		       ASM_OUTPUT2("=a" (eax), "=d" (edx)),
47		       "a" (0U), "d" (0U) : "ecx", "memory");
48	ret = (((unsigned long long)edx) << 32) | ((unsigned long long)eax);
49	if (ret)
50		return ret;
51
52	/*
53	 * Don't do an additional sync on CPUs where we know
54	 * RDTSC is already synchronous:
55	 */
56	alternative_io("cpuid", ASM_NOP2, X86_FEATURE_SYNC_RDTSC,
57			  "=a" (eax), "0" (1) : "ebx","ecx","edx","memory");
58	rdtscll(ret);
59
60	return ret;
61}
62
63extern void tsc_init(void);
64extern void mark_tsc_unstable(char *reason);
65extern int unsynchronized_tsc(void);
66extern void init_tsc_clocksource(void);
67int check_tsc_unstable(void);
68
69/*
70 * Boot-time check whether the TSCs are synchronized across
71 * all CPUs/cores:
72 */
73extern void check_tsc_sync_source(int cpu);
74extern void check_tsc_sync_target(void);
75
76#ifdef CONFIG_X86_64
77extern void tsc_calibrate(void);
78#endif
79
80#endif
81