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Linux kernel mirror (for testing)
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linux
1/*
2 * delay.h - delay functions
3 *
4 * Copyright (c) 2004-2007 Analog Devices Inc.
5 *
6 * Licensed under the GPL-2 or later.
7 */
8
9#ifndef __ASM_DELAY_H__
10#define __ASM_DELAY_H__
11
12#include <asm/mach/anomaly.h>
13
14static inline void __delay(unsigned long loops)
15{
16 if (ANOMALY_05000312) {
17 /* Interrupted loads to loop registers -> bad */
18 unsigned long tmp;
19 __asm__ __volatile__(
20 "[--SP] = LC0;"
21 "[--SP] = LT0;"
22 "[--SP] = LB0;"
23 "LSETUP (1f,1f) LC0 = %1;"
24 "1: NOP;"
25 /* We take advantage of the fact that LC0 is 0 at
26 * the end of the loop. Otherwise we'd need some
27 * NOPs after the CLI here.
28 */
29 "CLI %0;"
30 "LB0 = [SP++];"
31 "LT0 = [SP++];"
32 "LC0 = [SP++];"
33 "STI %0;"
34 : "=d" (tmp)
35 : "a" (loops)
36 );
37 } else
38 __asm__ __volatile__ (
39 "LSETUP(1f, 1f) LC0 = %0;"
40 "1: NOP;"
41 :
42 : "a" (loops)
43 : "LT0", "LB0", "LC0"
44 );
45}
46
47#include <linux/param.h> /* needed for HZ */
48
49/*
50 * Use only for very small delays ( < 1 msec). Should probably use a
51 * lookup table, really, as the multiplications take much too long with
52 * short delays. This is a "reasonable" implementation, though (and the
53 * first constant multiplications gets optimized away if the delay is
54 * a constant)
55 */
56static inline void udelay(unsigned long usecs)
57{
58 extern unsigned long loops_per_jiffy;
59 __delay(usecs * loops_per_jiffy / (1000000 / HZ));
60}
61
62#endif