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 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/config.h> 14#include <linux/param.h> 15 16extern unsigned long loops_per_jiffy; 17 18extern __inline__ void 19__delay(unsigned long loops) 20{ 21 __asm__ __volatile__ ( 22 ".set\tnoreorder\n" 23 "1:\tbnez\t%0,1b\n\t" 24 "dsubu\t%0,1\n\t" 25 ".set\treorder" 26 :"=r" (loops) 27 :"0" (loops)); 28} 29 30/* 31 * Division by multiplication: you don't have to worry about 32 * loss of precision. 33 * 34 * Use only for very small delays ( < 1 msec). Should probably use a 35 * lookup table, really, as the multiplications take much too long with 36 * short delays. This is a "reasonable" implementation, though (and the 37 * first constant multiplications gets optimized away if the delay is 38 * a constant) 39 */ 40extern __inline__ void __udelay(unsigned long usecs, unsigned long lpj) 41{ 42 unsigned long lo; 43 44 /* 45 * The common rates of 1000 and 128 are rounded wrongly by the 46 * catchall case. Excessive precission? Probably ... 47 */ 48#if HZ == 128 49 usecs *= 0x0008637bd05af6c7UL; /* 2**64 / (1000000 / HZ) */ 50#elif HZ == 1000 51 usecs *= 0x004189374BC6A7f0UL; /* 2**64 / (1000000 / HZ) */ 52#else 53 usecs *= (0x8000000000000000UL / (500000 / HZ)); 54#endif 55 __asm__("dmultu\t%2,%3" 56 :"=h" (usecs), "=l" (lo) 57 :"r" (usecs),"r" (lpj)); 58 __delay(usecs); 59} 60 61#ifdef CONFIG_SMP 62#define __udelay_val cpu_data[smp_processor_id()].udelay_val 63#else 64#define __udelay_val loops_per_jiffy 65#endif 66 67#define udelay(usecs) __udelay((usecs),__udelay_val) 68 69#endif /* _ASM_DELAY_H */ 70