LXR uboot/arch/blackfin/include/asm/delay.h

   1/*
   2 * U-Boot - delay.h Routines for introducing delays
   3 *
   4 * Copyright (c) 2005-2007 Analog Devices Inc.
   5 *
   6 * SPDX-License-Identifier:     GPL-2.0+
   7 */
   8
   9#ifndef _BLACKFIN_DELAY_H
  10#define _BLACKFIN_DELAY_H
  11
  12/*
  13 * Changes made by akbar.hussain@Lineo.com, for BLACKFIN
  14 * Copyright (C) 1994 Hamish Macdonald
  15 *
  16 * Delay routines, using a pre-computed "loops_per_second" value.
  17 */
  18
  19static __inline__ void __delay(unsigned long loops)
  20{
  21        __asm__ __volatile__("1:\t%0 += -1;\n\t"
  22                             "cc = %0 == 0;\n\t"
  23                             "if ! cc jump 1b;\n":"=d"(loops)
  24                             :"0"(loops));
  25}
  26
  27/*
  28 * Use only for very small delays ( < 1 msec).  Should probably use a
  29 * lookup table, really, as the multiplications take much too long with
  30 * short delays.  This is a "reasonable" implementation, though (and the
  31 * first constant multiplications gets optimized away if the delay is
  32 * a constant)
  33 */
  34static __inline__ void __udelay(unsigned long usecs)
  35{
  36        __delay(usecs);
  37}
  38
  39#endif
  40