1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2020-2022 Loongson Technology Corporation Limited 4 */ 5 #include <linux/delay.h> 6 #include <linux/export.h> 7 #include <linux/smp.h> 8 #include <linux/timex.h> 9 10 #include <asm/processor.h> 11 12 void __delay(unsigned long cycles) 13 { 14 u64 t0 = get_cycles(); 15 16 while ((unsigned long)(get_cycles() - t0) < cycles) 17 cpu_relax(); 18 } 19 EXPORT_SYMBOL(__delay); 20 21 /* 22 * Division by multiplication: you don't have to worry about 23 * loss of precision. 24 * 25 * Use only for very small delays ( < 1 msec). Should probably use a 26 * lookup table, really, as the multiplications take much too long with 27 * short delays. This is a "reasonable" implementation, though (and the 28 * first constant multiplications gets optimized away if the delay is 29 * a constant) 30 */ 31 32 void __udelay(unsigned long us) 33 { 34 __delay((us * 0x000010c7ull * HZ * lpj_fine) >> 32); 35 } 36 EXPORT_SYMBOL(__udelay); 37 38 void __ndelay(unsigned long ns) 39 { 40 __delay((ns * 0x00000005ull * HZ * lpj_fine) >> 32); 41 } 42 EXPORT_SYMBOL(__ndelay); 43