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delay.h

/*
 * delay.h - delay functions
 *
 * Copyright (c) 2004-2007 Analog Devices Inc.
 *
 * Licensed under the GPL-2 or later.
 */

#ifndef __ASM_DELAY_H__
#define __ASM_DELAY_H__

#include <mach/anomaly.h>

static inline void __delay(unsigned long loops)
{
      if (ANOMALY_05000312) {
            /* Interrupted loads to loop registers -> bad */
            unsigned long tmp;
            __asm__ __volatile__(
                  "[--SP] = LC0;"
                  "[--SP] = LT0;"
                  "[--SP] = LB0;"
                  "LSETUP (1f,1f) LC0 = %1;"
                  "1: NOP;"
                  /* We take advantage of the fact that LC0 is 0 at
                   * the end of the loop.  Otherwise we'd need some
                   * NOPs after the CLI here.
                   */
                  "CLI %0;"
                  "LB0 = [SP++];"
                  "LT0 = [SP++];"
                  "LC0 = [SP++];"
                  "STI %0;"
                  : "=d" (tmp)
                  : "a" (loops)
            );
      } else
            __asm__ __volatile__ (
                  "LSETUP(1f, 1f) LC0 = %0;"
                  "1: NOP;"
                  :
                  : "a" (loops)
                  : "LT0", "LB0", "LC0"
            );
}

#include <linux/param.h>      /* needed for HZ */

/*
 * 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)
 */
static inline void udelay(unsigned long usecs)
{
      extern unsigned long loops_per_jiffy;
      __delay(usecs * loops_per_jiffy / (1000000 / HZ));
}

#endif

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