1/*
2 * This file is subject to the terms and conditions of the GNU General Public
3 * License.  See the file "COPYING" in the main directory of this archive
4 * for more details.
5 *
6 * Copyright (C) 1994 by Waldorf Electronics
7 * Copyright (C) 1995 - 2000 by Ralf Baechle
8 * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
9 */
10#ifndef _ASM_DELAY_H
11#define _ASM_DELAY_H
12
13#include <linux/config.h>
14#include <linux/param.h>
15
16extern unsigned long loops_per_jiffy;
17
18extern __inline__ void
19__delay(unsigned long loops)
20{
21	__asm__ __volatile__ (
22		".set\tnoreorder\n"
23		"1:\tbnez\t%0,1b\n\t"
24		"dsubu\t%0,1\n\t"
25		".set\treorder"
26		:"=r" (loops)
27		:"0" (loops));
28}
29
30/*
31 * Division by multiplication: you don't have to worry about
32 * loss of precision.
33 *
34 * Use only for very small delays ( < 1 msec).  Should probably use a
35 * lookup table, really, as the multiplications take much too long with
36 * short delays.  This is a "reasonable" implementation, though (and the
37 * first constant multiplications gets optimized away if the delay is
38 * a constant)
39 */
40extern __inline__ void __udelay(unsigned long usecs, unsigned long lpj)
41{
42	unsigned long lo;
43
44	/*
45	 * The common rates of 1000 and 128 are rounded wrongly by the
46	 * catchall case.  Excessive precission?  Probably ...
47	 */
48#if HZ == 128
49	usecs *= 0x0008637bd05af6c7UL;		/* 2**64 / (1000000 / HZ) */
50#elif HZ == 1000
51	usecs *= 0x004189374BC6A7f0UL;		/* 2**64 / (1000000 / HZ) */
52#else
53	usecs *= (0x8000000000000000UL / (500000 / HZ));
54#endif
55	__asm__("dmultu\t%2,%3"
56		:"=h" (usecs), "=l" (lo)
57		:"r" (usecs),"r" (lpj));
58	__delay(usecs);
59}
60
61#ifdef CONFIG_SMP
62#define __udelay_val cpu_data[smp_processor_id()].udelay_val
63#else
64#define __udelay_val loops_per_jiffy
65#endif
66
67#define udelay(usecs) __udelay((usecs),__udelay_val)
68
69#endif /* _ASM_DELAY_H */
70