2 * linux/include/asm-x86_64/timex.h
4 * x86-64 architecture timex specifications
6 #ifndef _ASMx8664_TIMEX_H
7 #define _ASMx8664_TIMEX_H
9 #include <asm/8253pit.h>
11 #include <asm/vsyscall.h>
12 #include <asm/system.h>
13 #include <asm/processor.h>
15 #include <linux/compiler.h>
17 #define CLOCK_TICK_RATE PIT_TICK_RATE /* Underlying HZ */
19 extern int read_current_timer(unsigned long *timer_value);
20 #define ARCH_HAS_READ_CURRENT_TIMER 1
22 #define USEC_PER_TICK (USEC_PER_SEC / HZ)
23 #define NSEC_PER_TICK (NSEC_PER_SEC / HZ)
24 #define FSEC_PER_TICK (FSEC_PER_SEC / HZ)
26 #define NS_SCALE 10 /* 2^10, carefully chosen */
27 #define US_SCALE 32 /* 2^32, arbitralrily chosen */
29 extern void mark_tsc_unstable(char *msg);
30 extern void set_cyc2ns_scale(unsigned long khz);