45 строки
1.2 KiB
C
45 строки
1.2 KiB
C
|
/*
|
||
|
|
* Copyright (C) 1995-2004 Russell King
|
||
|
|
*
|
||
|
|
* Delay routines, using a pre-computed "loops_per_second" value.
|
||
|
|
*/
|
||
|
|
#ifndef __ASM_ARM_DELAY_H
|
||
|
|
#define __ASM_ARM_DELAY_H
|
||
|
|
|
||
|
#include <asm/param.h> /* HZ */
|
||
|
|
|
||
|
|
extern void __delay(int loops);
|
||
|
|
|
||
|
|
/*
|
||
|
|
* This function intentionally does not exist; if you see references to
|
||
|
|
* it, it means that you're calling udelay() with an out of range value.
|
||
|
|
*
|
||
|
|
* With currently imposed limits, this means that we support a max delay
|
||
|
|
* of 2000us. Further limits: HZ<=1000 and bogomips<=3355
|
||
|
|
*/
|
||
|
|
extern void __bad_udelay(void);
|
||
|
|
|
||
|
|
/*
|
||
|
|
* division by multiplication: you don't have to worry about
|
||
|
|
* loss of precision.
|
||
|
|
*
|
||
|
|
* Use only for very small delays ( < 1 msec). Should probably use a
|
||
|
|
* lookup table, really, as the multiplications take much too long with
|
||
|
|
* short delays. This is a "reasonable" implementation, though (and the
|
||
|
|
* first constant multiplications gets optimized away if the delay is
|
||
|
|
* a constant)
|
||
|
|
*/
|
||
|
|
extern void __udelay(unsigned long usecs);
|
||
|
|
extern void __const_udelay(unsigned long);
|
||
|
|
|
||
|
|
#define MAX_UDELAY_MS 2
|
||
|
|
|
||
|
|
#define udelay(n) \
|
||
|
|
(__builtin_constant_p(n) ? \
|
||
|
|
((n) > (MAX_UDELAY_MS * 1000) ? __bad_udelay() : \
|
||
|
|
__const_udelay((n) * ((2199023U*HZ)>>11))) : \
|
||
|
|
__udelay(n))
|
||
|
|
|
||
|
|
#endif /* defined(_ARM_DELAY_H) */
|
||
|
|
|