arch/x86/include/asm/tsc.h

   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
  22 static inline cycles_t get_cycles(void)
  23 {
  24 #ifndef CONFIG_X86_TSC
  25         if (!cpu_has_tsc)
  26                 return 0;
  27 #endif
  28
  29         return rdtsc();
  30 }
  31
  32 extern struct system_counterval_t convert_art_to_tsc(cycle_t art);
  33
  34 extern void tsc_init(void);
  35 extern void mark_tsc_unstable(char *reason);
  36 extern int unsynchronized_tsc(void);
  37 extern int check_tsc_unstable(void);
  38 extern int check_tsc_disabled(void);
  39 extern unsigned long native_calibrate_tsc(void);
  40 extern unsigned long long native_sched_clock_from_tsc(u64 tsc);
  41
  42 extern int tsc_clocksource_reliable;
  43
  44 /*
  45  * Boot-time check whether the TSCs are synchronized across
  46  * all CPUs/cores:
  47  */
  48 extern void check_tsc_sync_source(int cpu);
  49 extern void check_tsc_sync_target(void);
  50
  51 extern int notsc_setup(char *);
  52 extern void tsc_save_sched_clock_state(void);
  53 extern void tsc_restore_sched_clock_state(void);
  54
  55 /* MSR based TSC calibration for Intel Atom SoC platforms */
  56 unsigned long try_msr_calibrate_tsc(void);
  57
  58 #endif /* _ASM_X86_TSC_H */