1 /* 2 * Delay loops based on the OpenRISC implementation. 3 * 4 * Copyright (C) 2012 ARM Limited 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 * 10 * This program is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 * GNU General Public License for more details. 14 * 15 * You should have received a copy of the GNU General Public License 16 * along with this program. If not, see <http://www.gnu.org/licenses/>. 17 * 18 * Author: Will Deacon <will.deacon@arm.com> 19 */ 20 21 #include <linux/delay.h> 22 #include <linux/init.h> 23 #include <linux/kernel.h> 24 #include <linux/module.h> 25 #include <linux/timex.h> 26 27 void __delay(unsigned long cycles) 28 { 29 cycles_t start = get_cycles(); 30 31 while ((get_cycles() - start) < cycles) 32 cpu_relax(); 33 } 34 EXPORT_SYMBOL(__delay); 35 36 inline void __const_udelay(unsigned long xloops) 37 { 38 unsigned long loops; 39 40 loops = xloops * loops_per_jiffy * HZ; 41 __delay(loops >> 32); 42 } 43 EXPORT_SYMBOL(__const_udelay); 44 45 void __udelay(unsigned long usecs) 46 { 47 __const_udelay(usecs * 0x10C7UL); /* 2**32 / 1000000 (rounded up) */ 48 } 49 EXPORT_SYMBOL(__udelay); 50 51 void __ndelay(unsigned long nsecs) 52 { 53 __const_udelay(nsecs * 0x5UL); /* 2**32 / 1000000000 (rounded up) */ 54 } 55 EXPORT_SYMBOL(__ndelay); 56