1/* SPDX-License-Identifier: GPL-2.0 */ 2#ifndef _LINUX_DELAY_H 3#define _LINUX_DELAY_H 4 5/* 6 * Copyright (C) 1993 Linus Torvalds 7 * 8 * Delay routines, using a pre-computed "loops_per_jiffy" value. 9 * 10 * Please note that ndelay(), udelay() and mdelay() may return early for 11 * several reasons: 12 * 1. computed loops_per_jiffy too low (due to the time taken to 13 * execute the timer interrupt.) 14 * 2. cache behaviour affecting the time it takes to execute the 15 * loop function. 16 * 3. CPU clock rate changes. 17 * 18 * Please see this thread: 19 * http://lists.openwall.net/linux-kernel/2011/01/09/56 20 */ 21 22#include <linux/kernel.h> 23 24extern unsigned long loops_per_jiffy; 25 26#include <asm/delay.h> 27 28/* 29 * Using udelay() for intervals greater than a few milliseconds can 30 * risk overflow for high loops_per_jiffy (high bogomips) machines. The 31 * mdelay() provides a wrapper to prevent this. For delays greater 32 * than MAX_UDELAY_MS milliseconds, the wrapper is used. Architecture 33 * specific values can be defined in asm-???/delay.h as an override. 34 * The 2nd mdelay() definition ensures GCC will optimize away the 35 * while loop for the common cases where n <= MAX_UDELAY_MS -- Paul G. 36 */ 37 38#ifndef MAX_UDELAY_MS 39#define MAX_UDELAY_MS 5 40#endif 41 42#ifndef mdelay 43#define mdelay(n) (\ 44 (__builtin_constant_p(n) && (n)<=MAX_UDELAY_MS) ? udelay((n)*1000) : \ 45 ({unsigned long __ms=(n); while (__ms--) udelay(1000);})) 46#endif 47 48#ifndef ndelay 49static inline void ndelay(unsigned long x) 50{ 51 udelay(DIV_ROUND_UP(x, 1000)); 52} 53#define ndelay(x) ndelay(x) 54#endif 55 56extern unsigned long lpj_fine; 57void calibrate_delay(void); 58void msleep(unsigned int msecs); 59unsigned long msleep_interruptible(unsigned int msecs); 60void usleep_range(unsigned long min, unsigned long max); 61 62static inline void ssleep(unsigned int seconds) 63{ 64 msleep(seconds * 1000); 65} 66 67#endif /* defined(_LINUX_DELAY_H) */ 68