1 /* SPDX-License-Identifier: GPL-2.0 */
3 * x86 TSC related functions
8 #include <asm/processor.h>
10 #define NS_SCALE 10 /* 2^10, carefully chosen */
11 #define US_SCALE 32 /* 2^32, arbitralrily chosen */
14 * Standard way to access the cycle counter.
16 typedef unsigned long long cycles_t;
18 extern unsigned int cpu_khz;
19 extern unsigned int tsc_khz;
21 extern void disable_TSC(void);
23 static inline cycles_t get_cycles(void)
25 #ifndef CONFIG_X86_TSC
26 if (!boot_cpu_has(X86_FEATURE_TSC))
33 extern struct system_counterval_t convert_art_to_tsc(u64 art);
35 extern void tsc_init(void);
36 extern void mark_tsc_unstable(char *reason);
37 extern int unsynchronized_tsc(void);
38 extern int check_tsc_unstable(void);
39 extern unsigned long native_calibrate_cpu(void);
40 extern unsigned long native_calibrate_tsc(void);
41 extern unsigned long long native_sched_clock_from_tsc(u64 tsc);
43 extern int tsc_clocksource_reliable;
46 * Boot-time check whether the TSCs are synchronized across
50 extern bool tsc_store_and_check_tsc_adjust(bool bootcpu);
51 extern void tsc_verify_tsc_adjust(bool resume);
52 extern void check_tsc_sync_source(int cpu);
53 extern void check_tsc_sync_target(void);
55 static inline bool tsc_store_and_check_tsc_adjust(bool bootcpu) { return false; }
56 static inline void tsc_verify_tsc_adjust(bool resume) { }
57 static inline void check_tsc_sync_source(int cpu) { }
58 static inline void check_tsc_sync_target(void) { }
61 extern int notsc_setup(char *);
62 extern void tsc_save_sched_clock_state(void);
63 extern void tsc_restore_sched_clock_state(void);
65 unsigned long cpu_khz_from_msr(void);
67 #endif /* _ASM_X86_TSC_H */