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Andres Salomon2272b0e2007-03-06 01:42:05 -08001/*
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;
Joerg Roedel6041b572007-05-10 22:22:14 -070038 unsigned eax, edx;
Andres Salomon2272b0e2007-03-06 01:42:05 -080039
40 /*
Andi Kleenc5bcb562007-05-02 19:27:21 +020041 * 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,
Joerg Roedel6041b572007-05-10 22:22:14 -070045 ASM_OUTPUT2("=a" (eax), "=d" (edx)),
46 "a" (0U), "d" (0U) : "ecx", "memory");
47 ret = (((unsigned long long)edx) << 32) | ((unsigned long long)eax);
Andi Kleenc5bcb562007-05-02 19:27:21 +020048 if (ret)
49 return ret;
50
51 /*
Andres Salomon2272b0e2007-03-06 01:42:05 -080052 * 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");
Andres Salomon2272b0e2007-03-06 01:42:05 -080057 rdtscll(ret);
58
59 return ret;
60}
61
62extern void tsc_init(void);
john stultz5a90cf22007-05-02 19:27:08 +020063extern void mark_tsc_unstable(char *reason);
Andres Salomon2272b0e2007-03-06 01:42:05 -080064extern int unsynchronized_tsc(void);
65extern void init_tsc_clocksource(void);
Rusty Russelld7e28ff2007-07-19 01:49:23 -070066int check_tsc_unstable(void);
Andres Salomon2272b0e2007-03-06 01:42:05 -080067
68/*
69 * Boot-time check whether the TSCs are synchronized across
70 * all CPUs/cores:
71 */
72extern void check_tsc_sync_source(int cpu);
73extern void check_tsc_sync_target(void);
74
75#endif