| 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 (alternative_has_cap_unlikely(ARM64_HAS_WFXT)) { |
| 31 | u64 end = start + cycles; |
| 32 | |
| 33 | /* |
| 34 | * Start with WFIT. If an interrupt makes us resume |
| 35 | * early, use a WFET loop to complete the delay. |
| 36 | */ |
| 37 | wfit(end); |
| 38 | while ((get_cycles() - start) < cycles) |
| 39 | wfet(end); |
| 40 | } else if (arch_timer_evtstrm_available()) { |
| 41 | const cycles_t timer_evt_period = |
| 42 | USECS_TO_CYCLES(ARCH_TIMER_EVT_STREAM_PERIOD_US); |
| 43 | |
| 44 | while ((get_cycles() - start + timer_evt_period) < cycles) |
| 45 | wfe(); |
| 46 | } |
| 47 | |
| 48 | while ((get_cycles() - start) < cycles) |
| 49 | cpu_relax(); |
| 50 | } |
| 51 | EXPORT_SYMBOL(__delay); |
| 52 | |
| 53 | inline void __const_udelay(unsigned long xloops) |
| 54 | { |
| 55 | __delay(xloops_to_cycles(xloops)); |
| 56 | } |
| 57 | EXPORT_SYMBOL(__const_udelay); |
| 58 | |
| 59 | void __udelay(unsigned long usecs) |
| 60 | { |
| 61 | __const_udelay(usecs * 0x10C7UL); /* 2**32 / 1000000 (rounded up) */ |
| 62 | } |
| 63 | EXPORT_SYMBOL(__udelay); |
| 64 | |
| 65 | void __ndelay(unsigned long nsecs) |
| 66 | { |
| 67 | __const_udelay(nsecs * 0x5UL); /* 2**32 / 1000000000 (rounded up) */ |
| 68 | } |
| 69 | EXPORT_SYMBOL(__ndelay); |
| 70 |