delay.c

Go to the documentation of this file.

/*
 * 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>

void __delay(unsigned long loops)
{
    __asm__ __volatile__ (
    "   .set    noreorder               \n"
    "   .align  3                   \n"
    "1: bnez    %0, 1b                  \n"
#if __SIZEOF_LONG__ == 4
    "   subu    %0, 1                   \n"
#else
    "   dsubu   %0, 1                   \n"
#endif
    "   .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 = raw_current_cpu_data.udelay_val;

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

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

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