mirror of
https://github.com/torvalds/linux
synced 2024-11-05 18:23:50 +00:00
539eb11e6e
As part of the i386 conversion to the generic timekeeping infrastructure, this introduces a new tsc.c file. The code in this file replaces the TSC initialization, management and access code currently in timer_tsc.c (which will be removed) that we want to preserve. The code also introduces the following functionality: o tsc_khz: like cpu_khz but stores the TSC frequency on systems that do not change TSC frequency w/ CPU frequency o check/mark_tsc_unstable: accessor/modifier flag for TSC timekeeping usability o minor cleanups to calibration math. This patch also includes a one line __cpuinitdata fix from Zwane Mwaikambo. Signed-off-by: John Stultz <johnstul@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
49 lines
1.1 KiB
C
49 lines
1.1 KiB
C
/*
|
|
* linux/include/asm-i386/tsc.h
|
|
*
|
|
* i386 TSC related functions
|
|
*/
|
|
#ifndef _ASM_i386_TSC_H
|
|
#define _ASM_i386_TSC_H
|
|
|
|
#include <linux/config.h>
|
|
#include <asm/processor.h>
|
|
|
|
/*
|
|
* Standard way to access the cycle counter on i586+ CPUs.
|
|
* Currently only used on SMP.
|
|
*
|
|
* If you really have a SMP machine with i486 chips or older,
|
|
* compile for that, and this will just always return zero.
|
|
* That's ok, it just means that the nicer scheduling heuristics
|
|
* won't work for you.
|
|
*
|
|
* We only use the low 32 bits, and we'd simply better make sure
|
|
* that we reschedule before that wraps. Scheduling at least every
|
|
* four billion cycles just basically sounds like a good idea,
|
|
* regardless of how fast the machine is.
|
|
*/
|
|
typedef unsigned long long cycles_t;
|
|
|
|
extern unsigned int cpu_khz;
|
|
extern unsigned int tsc_khz;
|
|
|
|
static inline cycles_t get_cycles(void)
|
|
{
|
|
unsigned long long ret = 0;
|
|
|
|
#ifndef CONFIG_X86_TSC
|
|
if (!cpu_has_tsc)
|
|
return 0;
|
|
#endif
|
|
|
|
#if defined(CONFIG_X86_GENERIC) || defined(CONFIG_X86_TSC)
|
|
rdtscll(ret);
|
|
#endif
|
|
return ret;
|
|
}
|
|
|
|
extern void tsc_init(void);
|
|
extern void mark_tsc_unstable(void);
|
|
|
|
#endif
|