include/asm-blackfin/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
  35 extern __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  */
  50 extern __inline__ void udelay(unsigned long usecs)
  51 {
  52         __delay(usecs);
  53 }
  54
  55 #endif