1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Delay loops based on the OpenRISC implementation. 4 * 5 * Copyright (C) 2012 ARM Limited 6 * 7 * Author: Will Deacon <will.deacon@arm.com> 8 */ 9 10 #include <linux/delay.h> 11 #include <linux/init.h> 12 #include <linux/kernel.h> 13 #include <linux/module.h> 14 #include <linux/timex.h> 15 16 #include <clocksource/arm_arch_timer.h> 17 18 #define USECS_TO_CYCLES(time_usecs) \ 19 xloops_to_cycles((time_usecs) * 0x10C7UL) 20 21 static inline unsigned long xloops_to_cycles(unsigned long xloops) 22 { 23 return (xloops * loops_per_jiffy * HZ) >> 32; 24 } 25 26 void __delay(unsigned long cycles) 27 { 28 cycles_t start = get_cycles(); 29 30 if (arch_timer_evtstrm_available()) { 31 const cycles_t timer_evt_period = 32 USECS_TO_CYCLES(ARCH_TIMER_EVT_STREAM_PERIOD_US); 33 34 while ((get_cycles() - start + timer_evt_period) < cycles) 35 wfe(); 36 } 37 38 while ((get_cycles() - start) < cycles) 39 cpu_relax(); 40 } 41 EXPORT_SYMBOL(__delay); 42 43 inline void __const_udelay(unsigned long xloops) 44 { 45 __delay(xloops_to_cycles(xloops)); 46 } 47 EXPORT_SYMBOL(__const_udelay); 48 49 void __udelay(unsigned long usecs) 50 { 51 __const_udelay(usecs * 0x10C7UL); /* 2**32 / 1000000 (rounded up) */ 52 } 53 EXPORT_SYMBOL(__udelay); 54 55 void __ndelay(unsigned long nsecs) 56 { 57 __const_udelay(nsecs * 0x5UL); /* 2**32 / 1000000000 (rounded up) */ 58 } 59 EXPORT_SYMBOL(__ndelay); 60