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delay.h

/*
 * 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
 */
#ifndef _ASM_DELAY_H
#define _ASM_DELAY_H

#include <linux/param.h>
#include <linux/smp.h>

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

static inline void __delay(unsigned long loops)
{
      if (sizeof(long) == 4)
            __asm__ __volatile__ (
            "     .set  noreorder                     \n"
            "     .align      3                             \n"
            "1:   bnez  %0, 1b                              \n"
            "     subu  %0, 1                         \n"
            "     .set  reorder                             \n"
            : "=r" (loops)
            : "0" (loops));
      else if (sizeof(long) == 8 && !DADDI_WAR)
            __asm__ __volatile__ (
            "     .set  noreorder                     \n"
            "     .align      3                             \n"
            "1:   bnez  %0, 1b                              \n"
            "     dsubu %0, 1                         \n"
            "     .set  reorder                             \n"
            : "=r" (loops)
            : "0" (loops));
      else if (sizeof(long) == 8 && DADDI_WAR)
            __asm__ __volatile__ (
            "     .set  noreorder                     \n"
            "     .align      3                             \n"
            "1:   bnez  %0, 1b                              \n"
            "     dsubu %0, %2                              \n"
            "     .set  reorder                             \n"
            : "=r" (loops)
            : "0" (loops), "r" (1));
}


/*
 * 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)
 */

static inline void __udelay(unsigned long usecs, unsigned long lpj)
{
      unsigned long hi, lo;

      /*
       * The rates of 128 is rounded wrongly by the catchall case
       * for 64-bit.  Excessive precission?  Probably ...
       */
#if defined(CONFIG_64BIT) && (HZ == 128)
      usecs *= 0x0008637bd05af6c7UL;            /* 2**64 / (1000000 / HZ) */
#elif defined(CONFIG_64BIT)
      usecs *= (0x8000000000000000UL / (500000 / HZ));
#else /* 32-bit junk follows here */
      usecs *= (unsigned long) (((0x8000000000000000ULL / (500000 / HZ)) +
                                 0x80000000ULL) >> 32);
#endif

      if (sizeof(long) == 4)
            __asm__("multu\t%2, %3"
            : "=h" (usecs), "=l" (lo)
            : "r" (usecs), "r" (lpj)
            : GCC_REG_ACCUM);
      else if (sizeof(long) == 8 && !R4000_WAR)
            __asm__("dmultu\t%2, %3"
            : "=h" (usecs), "=l" (lo)
            : "r" (usecs), "r" (lpj)
            : GCC_REG_ACCUM);
      else if (sizeof(long) == 8 && R4000_WAR)
            __asm__("dmultu\t%3, %4\n\tmfhi\t%0"
            : "=r" (usecs), "=h" (hi), "=l" (lo)
            : "r" (usecs), "r" (lpj)
            : GCC_REG_ACCUM);

      __delay(usecs);
}

#define __udelay_val cpu_data[raw_smp_processor_id()].udelay_val

#define udelay(usecs) __udelay((usecs), __udelay_val)

/* make sure "usecs *= ..." in udelay do not overflow. */
#if HZ >= 1000
#define MAX_UDELAY_MS   1
#elif HZ <= 200
#define MAX_UDELAY_MS   5
#else
#define MAX_UDELAY_MS   (1000 / HZ)
#endif

#endif /* _ASM_DELAY_H */

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