71 строка
1.8 KiB
C
71 строка
1.8 KiB
C
/*
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* Delay loops based on the OpenRISC implementation.
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*
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* Copyright (C) 2012 ARM Limited
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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* Author: Will Deacon <will.deacon@arm.com>
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*/
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#include <linux/delay.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/timex.h>
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#include <clocksource/arm_arch_timer.h>
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#define USECS_TO_CYCLES(time_usecs) \
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xloops_to_cycles((time_usecs) * 0x10C7UL)
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static inline unsigned long xloops_to_cycles(unsigned long xloops)
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{
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return (xloops * loops_per_jiffy * HZ) >> 32;
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}
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void __delay(unsigned long cycles)
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{
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cycles_t start = get_cycles();
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if (arch_timer_evtstrm_available()) {
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const cycles_t timer_evt_period =
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USECS_TO_CYCLES(ARCH_TIMER_EVT_STREAM_PERIOD_US);
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while ((get_cycles() - start + timer_evt_period) < cycles)
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wfe();
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}
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while ((get_cycles() - start) < cycles)
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cpu_relax();
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}
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EXPORT_SYMBOL(__delay);
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inline void __const_udelay(unsigned long xloops)
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{
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__delay(xloops_to_cycles(xloops));
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}
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EXPORT_SYMBOL(__const_udelay);
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void __udelay(unsigned long usecs)
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{
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__const_udelay(usecs * 0x10C7UL); /* 2**32 / 1000000 (rounded up) */
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}
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EXPORT_SYMBOL(__udelay);
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void __ndelay(unsigned long nsecs)
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{
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__const_udelay(nsecs * 0x5UL); /* 2**32 / 1000000000 (rounded up) */
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}
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EXPORT_SYMBOL(__ndelay);
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