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delay.c

/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 1994 by Waldorf Electronics
 * Copyright (C) 1995 - 2000, 01, 03 by Ralf Baechle
 * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
 * Copyright (C) 2007  Maciej W. Rozycki
 */
#include <linux/module.h>
#include <linux/param.h>
#include <linux/smp.h>

#include <asm/compiler.h>
#include <asm/war.h>

inline void __delay(unsigned int loops)
{
      __asm__ __volatile__ (
      "     .set  noreorder                     \n"
      "     .align      3                             \n"
      "1:   bnez  %0, 1b                              \n"
      "     subu  %0, 1                         \n"
      "     .set  reorder                             \n"
      : "=r" (loops)
      : "0" (loops));
}
EXPORT_SYMBOL(__delay);

/*
 * Division by multiplication: you don't have to worry about
 * loss of precision.
 *
 * Use only for very small delays ( < 1 msec).  Should probably use a
 * lookup table, really, as the multiplications take much too long with
 * short delays.  This is a "reasonable" implementation, though (and the
 * first constant multiplications gets optimized away if the delay is
 * a constant)
 */

void __udelay(unsigned long us)
{
      unsigned int lpj = current_cpu_data.udelay_val;

      __delay((us * 0x000010c7ull * HZ * lpj) >> 32);
}
EXPORT_SYMBOL(__udelay);

void __ndelay(unsigned long ns)
{
      unsigned int lpj = current_cpu_data.udelay_val;

      __delay((ns * 0x00000005ull * HZ * lpj) >> 32);
}
EXPORT_SYMBOL(__ndelay);

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