tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * linux/include/asm-i386/timex.h
3 *
4 * i386 architecture timex specifications
5 */
6#ifndef _ASMi386_TIMEX_H
7#define _ASMi386_TIMEX_H
8
9#include <linux/config.h>
10#include <asm/processor.h>
11
12#ifdef CONFIG_X86_ELAN
13# define CLOCK_TICK_RATE 1189200 /* AMD Elan has different frequency! */
14#else
15# define CLOCK_TICK_RATE 1193182 /* Underlying HZ */
16#endif
17
18
19/*
20 * Standard way to access the cycle counter on i586+ CPUs.
21 * Currently only used on SMP.
22 *
23 * If you really have a SMP machine with i486 chips or older,
24 * compile for that, and this will just always return zero.
25 * That's ok, it just means that the nicer scheduling heuristics
26 * won't work for you.
27 *
28 * We only use the low 32 bits, and we'd simply better make sure
29 * that we reschedule before that wraps. Scheduling at least every
30 * four billion cycles just basically sounds like a good idea,
31 * regardless of how fast the machine is.
32 */
33typedef unsigned long long cycles_t;
34
35static inline cycles_t get_cycles (void)
36{
37 unsigned long long ret=0;
38
39#ifndef CONFIG_X86_TSC
40 if (!cpu_has_tsc)
41 return 0;
42#endif
43
44#if defined(CONFIG_X86_GENERIC) || defined(CONFIG_X86_TSC)
45 rdtscll(ret);
46#endif
47 return ret;
48}
49
50extern unsigned int cpu_khz;
51
52extern int read_current_timer(unsigned long *timer_value);
53#define ARCH_HAS_READ_CURRENT_TIMER 1
54
55#endif