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/arch/alpha/lib/udelay.c

https://bitbucket.org/evzijst/gittest
C | 55 lines | 37 code | 6 blank | 12 comment | 0 complexity | 8a2a214ab89d0a65f736c116c123bf9e MD5 | raw file
 1/*
 2 * Copyright (C) 1993, 2000 Linus Torvalds
 3 *
 4 * Delay routines, using a pre-computed "loops_per_jiffy" value.
 5 */
 6
 7#include <linux/config.h>
 8#include <linux/module.h>
 9#include <linux/sched.h> /* for udelay's use of smp_processor_id */
10#include <asm/param.h>
11#include <asm/smp.h>
12#include <linux/delay.h>
13
14/*
15 * Use only for very small delays (< 1 msec). 
16 *
17 * The active part of our cycle counter is only 32-bits wide, and
18 * we're treating the difference between two marks as signed.  On
19 * a 1GHz box, that's about 2 seconds.
20 */
21
22void
23__delay(int loops)
24{
25	int tmp;
26	__asm__ __volatile__(
27		"	rpcc %0\n"
28		"	addl %1,%0,%1\n"
29		"1:	rpcc %0\n"
30		"	subl %1,%0,%0\n"
31		"	bgt %0,1b"
32		: "=&r" (tmp), "=r" (loops) : "1"(loops));
33}
34
35#ifdef CONFIG_SMP
36#define LPJ	 cpu_data[smp_processor_id()].loops_per_jiffy
37#else
38#define LPJ	 loops_per_jiffy
39#endif
40
41void
42udelay(unsigned long usecs)
43{
44	usecs *= (((unsigned long)HZ << 32) / 1000000) * LPJ;
45	__delay((long)usecs >> 32);
46}
47EXPORT_SYMBOL(udelay);
48
49void
50ndelay(unsigned long nsecs)
51{
52	nsecs *= (((unsigned long)HZ << 32) / 1000000000) * LPJ;
53	__delay((long)nsecs >> 32);
54}
55EXPORT_SYMBOL(ndelay);