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 * See file CREDITS for list of people who contributed to this
   7 * project.
   8 *
   9 * This program is free software; you can redistribute it and/or
  10 * modify it under the terms of the GNU General Public License as
  11 * published by the Free Software Foundation; either version 2 of
  12 * the License, or (at your option) any later version.
  13 *
  14 * This program is distributed in the hope that it will be useful,
  15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 * GNU General Public License for more details.
  18 *
  19 * You should have received a copy of the GNU General Public License
  20 * along with this program; if not, write to the Free Software
  21 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
  22 * MA 02110-1301 USA
  23 */
  24
  25#ifndef _BLACKFIN_DELAY_H
  26#define _BLACKFIN_DELAY_H
  27
  28/*
  29 * Changes made by akbar.hussain@Lineo.com, for BLACKFIN
  30 * Copyright (C) 1994 Hamish Macdonald
  31 *
  32 * Delay routines, using a pre-computed "loops_per_second" value.
  33 */
  34
  35extern __inline__ void __delay(unsigned long loops)
  36{
  37        __asm__ __volatile__("1:\t%0 += -1;\n\t"
  38                             "cc = %0 == 0;\n\t"
  39                             "if ! cc jump 1b;\n":"=d"(loops)
  40                             :"0"(loops));
  41}
  42
  43/*
  44 * Use only for very small delays ( < 1 msec).  Should probably use a
  45 * lookup table, really, as the multiplications take much too long with
  46 * short delays.  This is a "reasonable" implementation, though (and the
  47 * first constant multiplications gets optimized away if the delay is
  48 * a constant)
  49 */
  50extern __inline__ void __udelay(unsigned long usecs)
  51{
  52        __delay(usecs);
  53}
  54
  55#endif
  56