1/*
2 * linux/include/asm-i386/tsc.h
3 *
4 * i386 TSC related functions
5 */
6#ifndef _ASM_i386_TSC_H
7#define _ASM_i386_TSC_H
8
9#include <asm/processor.h>
10
11/*
12 * Standard way to access the cycle counter.
13 */
14typedef unsigned long long cycles_t;
15
16extern unsigned int cpu_khz;
17extern unsigned int tsc_khz;
18
19static inline cycles_t get_cycles(void)
20{
21	unsigned long long ret = 0;
22
23#ifndef CONFIG_X86_TSC
24	if (!cpu_has_tsc)
25		return 0;
26#endif
27
28#if defined(CONFIG_X86_GENERIC) || defined(CONFIG_X86_TSC)
29	rdtscll(ret);
30#endif
31	return ret;
32}
33
34/* Like get_cycles, but make sure the CPU is synchronized. */
35static __always_inline cycles_t get_cycles_sync(void)
36{
37	unsigned long long ret;
38	unsigned eax, edx;
39
40	/*
41  	 * Use RDTSCP if possible; it is guaranteed to be synchronous
42 	 * and doesn't cause a VMEXIT on Hypervisors
43	 */
44	alternative_io(ASM_NOP3, ".byte 0x0f,0x01,0xf9", X86_FEATURE_RDTSCP,
45		       ASM_OUTPUT2("=a" (eax), "=d" (edx)),
46		       "a" (0U), "d" (0U) : "ecx", "memory");
47	ret = (((unsigned long long)edx) << 32) | ((unsigned long long)eax);
48	if (ret)
49		return ret;
50
51	/*
52	 * Don't do an additional sync on CPUs where we know
53	 * RDTSC is already synchronous:
54	 */
55	alternative_io("cpuid", ASM_NOP2, X86_FEATURE_SYNC_RDTSC,
56			  "=a" (eax), "0" (1) : "ebx","ecx","edx","memory");
57	rdtscll(ret);
58
59	return ret;
60}
61
62extern void tsc_init(void);
63extern void mark_tsc_unstable(char *reason);
64extern int unsynchronized_tsc(void);
65extern void init_tsc_clocksource(void);
66
67/*
68 * Boot-time check whether the TSCs are synchronized across
69 * all CPUs/cores:
70 */
71extern void check_tsc_sync_source(int cpu);
72extern void check_tsc_sync_target(void);
73
74#endif
75