include/asm-ppc/delay.h

   1 #ifndef _PPC_DELAY_H
   2 #define _PPC_DELAY_H
   3
   4 /*
   5  * Copyright 1996, Paul Mackerras.
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License
   9  * as published by the Free Software Foundation; either version
  10  * 2 of the License, or (at your option) any later version.
  11  */
  12
  13 extern unsigned long loops_per_sec;
  14
  15 extern __inline__ void __delay(unsigned int loops)
  16 {
  17         if (loops != 0)
  18                 __asm__ __volatile__("mtctr %0; 1: bdnz 1b" : :
  19                                      "r" (loops) : "ctr");
  20 }
  21
  22 extern __inline__ void udelay(unsigned long usecs)
  23 {
  24         unsigned long loops;
  25
  26         /* compute (usecs * 2^32 / 10^6) * loops_per_sec / 2^32 */
  27         usecs *= 0x10c6;                /* 2^32 / 10^6 */
  28         __asm__("mulhwu %0,%1,%2" : "=r" (loops) :
  29                 "r" (usecs), "r" (loops_per_sec));
  30         __delay(loops);
  31 }
  32
  33 #endif /* defined(_PPC_DELAY_H) */