1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * OpenRISC Linux 4 * 5 * Linux architectural port borrowing liberally from similar works of 6 * others. All original copyrights apply as per the original source 7 * declaration. 8 * 9 * Modifications for the OpenRISC architecture: 10 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se> 11 * 12 * Precise Delay Loops 13 */ 14 15 #include <linux/kernel.h> 16 #include <linux/export.h> 17 #include <linux/init.h> 18 #include <asm/param.h> 19 #include <asm/delay.h> 20 #include <asm/timex.h> 21 #include <asm/processor.h> 22 read_current_timer(unsigned long * timer_value)23 int read_current_timer(unsigned long *timer_value) 24 { 25 *timer_value = get_cycles(); 26 return 0; 27 } 28 __delay(unsigned long cycles)29 void __delay(unsigned long cycles) 30 { 31 cycles_t start = get_cycles(); 32 33 while ((get_cycles() - start) < cycles) 34 cpu_relax(); 35 } 36 EXPORT_SYMBOL(__delay); 37 __const_udelay(unsigned long xloops)38 inline void __const_udelay(unsigned long xloops) 39 { 40 unsigned long long loops; 41 42 loops = (unsigned long long)xloops * loops_per_jiffy * HZ; 43 44 __delay(loops >> 32); 45 } 46 EXPORT_SYMBOL(__const_udelay); 47 __udelay(unsigned long usecs)48 void __udelay(unsigned long usecs) 49 { 50 __const_udelay(usecs * 0x10C7UL); /* 2**32 / 1000000 (rounded up) */ 51 } 52 EXPORT_SYMBOL(__udelay); 53 __ndelay(unsigned long nsecs)54 void __ndelay(unsigned long nsecs) 55 { 56 __const_udelay(nsecs * 0x5UL); /* 2**32 / 1000000000 (rounded up) */ 57 } 58 EXPORT_SYMBOL(__ndelay); 59