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, 01, 03 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/param.h>
14#include <linux/smp.h>
15#include <asm/compiler.h>
16
17static inline void __delay(unsigned long loops)
18{
19	if (sizeof(long) == 4)
20		__asm__ __volatile__ (
21		"	.set	noreorder				\n"
22		"	.align	3					\n"
23		"1:	bnez	%0, 1b					\n"
24		"	subu	%0, 1					\n"
25		"	.set	reorder					\n"
26		: "=r" (loops)
27		: "0" (loops));
28	else if (sizeof(long) == 8)
29		__asm__ __volatile__ (
30		"	.set	noreorder				\n"
31		"	.align	3					\n"
32		"1:	bnez	%0, 1b					\n"
33		"	dsubu	%0, 1					\n"
34		"	.set	reorder					\n"
35		: "=r" (loops)
36		: "0" (loops));
37}
38
39
40/*
41 * Division by multiplication: you don't have to worry about
42 * loss of precision.
43 *
44 * Use only for very small delays ( < 1 msec).  Should probably use a
45 * lookup table, really, as the multiplications take much too long with
46 * short delays.  This is a "reasonable" implementation, though (and the
47 * first constant multiplications gets optimized away if the delay is
48 * a constant)
49 */
50
51static inline void __udelay(unsigned long usecs, unsigned long lpj)
52{
53	unsigned long lo;
54
55	/*
56	 * The rates of 128 is rounded wrongly by the catchall case
57	 * for 64-bit.  Excessive precission?  Probably ...
58	 */
59#if defined(CONFIG_64BIT) && (HZ == 128)
60	usecs *= 0x0008637bd05af6c7UL;		/* 2**64 / (1000000 / HZ) */
61#elif defined(CONFIG_64BIT)
62	usecs *= (0x8000000000000000UL / (500000 / HZ));
63#else /* 32-bit junk follows here */
64	usecs *= (unsigned long) (((0x8000000000000000ULL / (500000 / HZ)) +
65	                           0x80000000ULL) >> 32);
66#endif
67
68	if (sizeof(long) == 4)
69		__asm__("multu\t%2, %3"
70		: "=h" (usecs), "=l" (lo)
71		: "r" (usecs), "r" (lpj)
72		: GCC_REG_ACCUM);
73	else if (sizeof(long) == 8)
74		__asm__("dmultu\t%2, %3"
75		: "=h" (usecs), "=l" (lo)
76		: "r" (usecs), "r" (lpj)
77		: GCC_REG_ACCUM);
78
79	__delay(usecs);
80}
81
82#define __udelay_val cpu_data[raw_smp_processor_id()].udelay_val
83
84#define udelay(usecs) __udelay((usecs),__udelay_val)
85
86/* make sure "usecs *= ..." in udelay do not overflow. */
87#if HZ >= 1000
88#define MAX_UDELAY_MS	1
89#elif HZ <= 200
90#define MAX_UDELAY_MS	5
91#else
92#define MAX_UDELAY_MS	(1000 / HZ)
93#endif
94
95#endif /* _ASM_DELAY_H */
96