linux/include/linux/delay.h
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   1#ifndef _LINUX_DELAY_H
   2#define _LINUX_DELAY_H
   3
   4/*
   5 * Copyright (C) 1993 Linus Torvalds
   6 *
   7 * Delay routines, using a pre-computed "loops_per_jiffy" value.
   8 */
   9
  10#include <linux/kernel.h>
  11
  12extern unsigned long loops_per_jiffy;
  13
  14#include <asm/delay.h>
  15
  16/*
  17 * Using udelay() for intervals greater than a few milliseconds can
  18 * risk overflow for high loops_per_jiffy (high bogomips) machines. The
  19 * mdelay() provides a wrapper to prevent this.  For delays greater
  20 * than MAX_UDELAY_MS milliseconds, the wrapper is used.  Architecture
  21 * specific values can be defined in asm-???/delay.h as an override.
  22 * The 2nd mdelay() definition ensures GCC will optimize away the 
  23 * while loop for the common cases where n <= MAX_UDELAY_MS  --  Paul G.
  24 */
  25
  26#ifndef MAX_UDELAY_MS
  27#define MAX_UDELAY_MS   5
  28#endif
  29
  30#ifndef mdelay
  31#define mdelay(n) (\
  32        (__builtin_constant_p(n) && (n)<=MAX_UDELAY_MS) ? udelay((n)*1000) : \
  33        ({unsigned long __ms=(n); while (__ms--) udelay(1000);}))
  34#endif
  35
  36#ifndef ndelay
  37static inline void ndelay(unsigned long x)
  38{
  39        udelay(DIV_ROUND_UP(x, 1000));
  40}
  41#define ndelay(x) ndelay(x)
  42#endif
  43
  44extern unsigned long lpj_fine;
  45void calibrate_delay(void);
  46void msleep(unsigned int msecs);
  47unsigned long msleep_interruptible(unsigned int msecs);
  48void usleep_range(unsigned long min, unsigned long max);
  49
  50static inline void ssleep(unsigned int seconds)
  51{
  52        msleep(seconds * 1000);
  53}
  54
  55#endif /* defined(_LINUX_DELAY_H) */
  56
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