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Old 05-08-2005, 11:06 PM   #1
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How to use udelay() in uclinux-2.4.x

hi friends,
I have search the udelay() function in the uclinux-2.4.x/include/asm but i found only the prototype there, the declaration is not there.How i can use the delay in the uclinx-2.4.x.
please give me the code if any body is having. I am using motarola 5272 coldfire.

Old 05-09-2005, 06:48 AM   #2
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the file is /usr/src/linux/include/asm-m68k/delay.h and here is the code:
#ifndef _M68K_DELAY_H
#define _M68K_DELAY_H

#include <asm/param.h>

 * Copyright (C) 1994 Hamish Macdonald
 * Delay routines, using a pre-computed "loops_per_jiffy" value.

static inline void __delay(unsigned long loops)
        __asm__ __volatile__ ("1: subql #1,%0; jcc 1b"
                : "=d" (loops) : "0" (loops));

extern void __bad_udelay(void);
extern void __bad_ndelay(void);

 * 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)  
static inline void __const_udelay(unsigned long xloops)
        unsigned long tmp;

        __asm__ ("mulul %2,%0:%1"
                : "=d" (xloops), "=d" (tmp)
                : "d" (xloops), "1" (loops_per_jiffy));
        __delay(xloops * HZ);

static inline void __udelay(unsigned long usecs)
        __const_udelay(usecs * 4295);   /* 2**32 / 1000000 */

static inline void __ndelay(unsigned long nsecs)
        __const_udelay(nsecs * 5);      /* 2**32 / 1000000000 */

#define udelay(n) (__builtin_constant_p(n) ? \
        ((n) > 20000 ? __bad_udelay() : __const_udelay((n) * 4295)) : \

#define ndelay(n) (__builtin_constant_p(n) ? \
        ((n) > 20000 ? __bad_ndelay() : __const_udelay((n) * 5)) : \

static inline unsigned long muldiv(unsigned long a, unsigned long b,
                                   unsigned long c)
        unsigned long tmp;

        __asm__ ("mulul %2,%0:%1; divul %3,%0:%1"
                : "=d" (tmp), "=d" (a)
                : "d" (b), "d" (c), "1" (a));
        return a;

#endif /* defined(_M68K_DELAY_H) */


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