diff options
Diffstat (limited to 'arch/arm64/lib/delay.c')
| -rw-r--r-- | arch/arm64/lib/delay.c | 46 |
1 files changed, 30 insertions, 16 deletions
diff --git a/arch/arm64/lib/delay.c b/arch/arm64/lib/delay.c index dad4ec9bbfd1..cb2062e7e234 100644 --- a/arch/arm64/lib/delay.c +++ b/arch/arm64/lib/delay.c @@ -1,20 +1,9 @@ +// SPDX-License-Identifier: GPL-2.0-only /* * Delay loops based on the OpenRISC implementation. * * Copyright (C) 2012 ARM Limited * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License version 2 as - * published by the Free Software Foundation. - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU General Public License for more details. - * - * You should have received a copy of the GNU General Public License - * along with this program. If not, see <http://www.gnu.org/licenses/>. - * * Author: Will Deacon <will.deacon@arm.com> */ @@ -24,10 +13,38 @@ #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 (alternative_has_cap_unlikely(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(); } @@ -35,10 +52,7 @@ EXPORT_SYMBOL(__delay); inline void __const_udelay(unsigned long xloops) { - unsigned long loops; - - loops = xloops * loops_per_jiffy * HZ; - __delay(loops >> 32); + __delay(xloops_to_cycles(xloops)); } EXPORT_SYMBOL(__const_udelay); |