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 - 1998, 2001 by Ralf Baechle
8 */
9#ifndef _ASM_DELAY_H
10#define _ASM_DELAY_H
11
12#include <linux/config.h>
13#include <linux/param.h>
14
15extern unsigned long loops_per_jiffy;
16
17extern __inline__ void
18__delay(unsigned long loops)
19{
20	__asm__ __volatile__ (
21		".set\tnoreorder\n"
22		"1:\tbnez\t%0,1b\n\t"
23		"subu\t%0,1\n\t"
24		".set\treorder"
25		:"=r" (loops)
26		:"0" (loops));
27}
28
29/*
30 * Division by multiplication: you don't have to worry about
31 * loss of precision.
32 *
33 * Use only for very small delays ( < 1 msec).  Should probably use a
34 * lookup table, really, as the multiplications take much too long with
35 * short delays.  This is a "reasonable" implementation, though (and the
36 * first constant multiplications gets optimized away if the delay is
37 * a constant)
38 */
39extern __inline__ void __udelay(unsigned long usecs, unsigned long lpj)
40{
41	unsigned long lo;
42
43	/*
44	 * Excessive precission?  Probably ...
45	 */
46	usecs *= (unsigned long) (((0x8000000000000000ULL / (500000 / HZ)) +
47	                           0x80000000ULL) >> 32);
48	__asm__("multu\t%2,%3"
49		:"=h" (usecs), "=l" (lo)
50		:"r" (usecs),"r" (lpj));
51	__delay(usecs);
52}
53
54#ifdef CONFIG_SMP
55#define __udelay_val cpu_data[smp_processor_id()].udelay_val
56#else
57#define __udelay_val loops_per_jiffy
58#endif
59
60#define udelay(usecs) __udelay((usecs),__udelay_val)
61
62#endif /* _ASM_DELAY_H */
63