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