55 строки
1.1 KiB
C
55 строки
1.1 KiB
C
|
/*
|
||
|
|
* Copyright (C) 1993, 2000 Linus Torvalds
|
||
|
|
*
|
||
|
|
* Delay routines, using a pre-computed "loops_per_jiffy" value.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include <linux/module.h>
|
||
|
|
#include <linux/sched.h> /* for udelay's use of smp_processor_id */
|
||
|
|
#include <asm/param.h>
|
||
|
|
#include <asm/smp.h>
|
||
|
|
#include <linux/delay.h>
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Use only for very small delays (< 1 msec).
|
||
|
|
*
|
||
|
|
* The active part of our cycle counter is only 32-bits wide, and
|
||
|
|
* we're treating the difference between two marks as signed. On
|
||
|
|
* a 1GHz box, that's about 2 seconds.
|
||
|
|
*/
|
||
|
|
|
||
|
|
void
|
||
|
|
__delay(int loops)
|
||
|
|
{
|
||
|
|
int tmp;
|
||
|
|
__asm__ __volatile__(
|
||
|
|
" rpcc %0\n"
|
||
|
|
" addl %1,%0,%1\n"
|
||
|
|
"1: rpcc %0\n"
|
||
|
|
" subl %1,%0,%0\n"
|
||
|
|
" bgt %0,1b"
|
||
|
|
: "=&r" (tmp), "=r" (loops) : "1"(loops));
|
||
|
|
}
|
||
|
|
|
||
|
|
#ifdef CONFIG_SMP
|
||
|
|
#define LPJ cpu_data[smp_processor_id()].loops_per_jiffy
|
||
|
|
#else
|
||
|
|
#define LPJ loops_per_jiffy
|
||
|
|
#endif
|
||
|
|
|
||
|
|
void
|
||
|
|
udelay(unsigned long usecs)
|
||
|
|
{
|
||
|
|
usecs *= (((unsigned long)HZ << 32) / 1000000) * LPJ;
|
||
|
|
__delay((long)usecs >> 32);
|
||
|
|
}
|
||
|
|
EXPORT_SYMBOL(udelay);
|
||
|
|
|
||
|
|
void
|
||
|
|
ndelay(unsigned long nsecs)
|
||
|
|
{
|
||
|
|
nsecs *= (((unsigned long)HZ << 32) / 1000000000) * LPJ;
|
||
|
|
__delay((long)nsecs >> 32);
|
||
|
|
}
|
||
|
|
EXPORT_SYMBOL(ndelay);
|