// SPDX-License-Identifier: GPL-2.0-only /* * Delay loops based on the OpenRISC implementation. * * Copyright (C) 2012 ARM Limited * * Author: Will Deacon <will.deacon@arm.com> */ #include <linux/delay.h> #include <linux/init.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/timex.h> #include <clocksource/arm_arch_timer.h> #define USECS_TO_CYCLES(time_usecs) \ xloops_to_cycles((time_usecs) * 0x10C7UL) static inline unsigned long xloops_to_cycles(unsigned long xloops) { return (xloops * loops_per_jiffy * HZ) >> 32; } void __delay(unsigned long cycles) { cycles_t start = get_cycles(); if (cpus_have_const_cap(ARM64_HAS_WFXT)) { u64 end = start + cycles; /* * Start with WFIT. If an interrupt makes us resume * early, use a WFET loop to complete the delay. */ wfit(end); while ((get_cycles() - start) < cycles) wfet(end); } else if (arch_timer_evtstrm_available()) { const cycles_t timer_evt_period = USECS_TO_CYCLES(ARCH_TIMER_EVT_STREAM_PERIOD_US); while ((get_cycles() - start + timer_evt_period) < cycles) wfe(); } while ((get_cycles() - start) < cycles) cpu_relax(); } EXPORT_SYMBOL(__delay); inline void __const_udelay(unsigned long xloops) { __delay(xloops_to_cycles(xloops)); } EXPORT_SYMBOL(__const_udelay); void __udelay(unsigned long usecs) { __const_udelay(usecs * 0x10C7UL); /* 2**32 / 1000000 (rounded up) */ } EXPORT_SYMBOL(__udelay); void __ndelay(unsigned long nsecs) { __const_udelay(nsecs * 0x5UL); /* 2**32 / 1000000000 (rounded up) */ } EXPORT_SYMBOL(__ndelay);