include/asm-mips64/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 by Ralf Baechle
 * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
 */
#ifndef _ASM_DELAY_H
#define _ASM_DELAY_H

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

#include <asm/compiler.h>

extern unsigned long loops_per_jiffy;

static __inline__ void
__delay(unsigned long loops)
{
	__asm__ __volatile__ (
		".set\tnoreorder\n"
		"1:\tbnez\t%0,1b\n\t"
		"dsubu\t%0,1\n\t"
		".set\treorder"
		:"=r" (loops)
		:"0" (loops));
}

/*
 * 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 lo;

	/*
	 * The common rates of 1000 and 128 are rounded wrongly by the
	 * catchall case.  Excessive precission?  Probably ...
	 */
#if (HZ == 128)
	usecs *= 0x0008637bd05af6c7UL;		/* 2**64 / (1000000 / HZ) */
#elif (HZ == 1000)
	usecs *= 0x004189374BC6A7f0UL;		/* 2**64 / (1000000 / HZ) */
#else
	usecs *= (0x8000000000000000UL / (500000 / HZ));
#endif
	__asm__("dmultu\t%2,%3"
		: "=h" (usecs), "=l" (lo)
		: "r" (usecs), "r" (lpj)
		: GCC_REG_ACCUM);
	__delay(usecs);
}

static inline void __ndelay(unsigned long nsecs, unsigned long lpj)
{
	unsigned long lo;

	/*
	 * The common rates of 1000 and 128 are rounded wrongly by the
	 * catchall case.  Excessive precission?  Probably ...
	 */
#if (HZ == 128)
	nsecs *= 0x000001ad7f29abcbUL;		/* 2**64 / (1000000000 / HZ) */
#elif (HZ == 1000)
	nsecs *= 0x0010c6f7a0b5eeUL;		/* 2**64 / (1000000000 / HZ) */
#else
	nsecs *= (0x8000000000000000UL / (500000000 / HZ));
#endif
	__asm__("dmultu\t%2,%3"
		: "=h" (nsecs), "=l" (lo)
		: "r" (nsecs), "r" (lpj)
		: GCC_REG_ACCUM);
	__delay(nsecs);
}

#ifdef CONFIG_SMP
#define __udelay_val cpu_data[smp_processor_id()].udelay_val
#else
#define __udelay_val loops_per_jiffy
#endif

#define udelay(usecs) __udelay((usecs),__udelay_val)
#define ndelay(nsecs) __ndelay((nsecs),__udelay_val)

#endif /* _ASM_DELAY_H */