LXR linux/arch/frv/include/asm/delay.h

   1/* delay.h: FRV delay code
   2 *
   3 * Copyright (C) 2003 Red Hat, Inc. All Rights Reserved.
   4 * Written by David Howells (dhowells@redhat.com)
   5 *
   6 * This program is free software; you can redistribute it and/or
   7 * modify it under the terms of the GNU General Public License
   8 * as published by the Free Software Foundation; either version
   9 * 2 of the License, or (at your option) any later version.
  10 */
  11
  12#ifndef _ASM_DELAY_H
  13#define _ASM_DELAY_H
  14
  15#include <asm/param.h>
  16#include <asm/timer-regs.h>
  17
  18/*
  19 * delay loop - runs at __core_clock_speed_HZ / 2 [there are 2 insns in the loop]
  20 */
  21extern unsigned long __delay_loops_MHz;
  22
  23static inline void __delay(unsigned long loops)
  24{
  25        asm volatile("1:        subicc  %0,#1,%0,icc0   \n"
  26                     "          bnc     icc0,#2,1b      \n"
  27                     : "=r" (loops)
  28                     : "0" (loops)
  29                     : "icc0"
  30                     );
  31}
  32
  33/*
  34 * Use only for very small delays ( < 1 msec).  Should probably use a
  35 * lookup table, really, as the multiplications take much too long with
  36 * short delays.  This is a "reasonable" implementation, though (and the
  37 * first constant multiplications gets optimized away if the delay is
  38 * a constant)
  39 */
  40
  41extern unsigned long loops_per_jiffy;
  42
  43static inline void udelay(unsigned long usecs)
  44{
  45        __delay(usecs * __delay_loops_MHz);
  46}
  47
  48#define ndelay(n)       udelay((n) * 5)
  49
  50#endif /* _ASM_DELAY_H */
  51