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1/*
2 * Delay loops based on the OpenRISC implementation.
3 *
4 * Copyright (C) 2012 ARM Limited
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program. If not, see <http://www.gnu.org/licenses/>.
17 *
18 * Author: Will Deacon <will.deacon@arm.com>
19 */
20
21#include <linux/delay.h>
22#include <linux/init.h>
23#include <linux/kernel.h>
24#include <linux/module.h>
25#include <linux/timex.h>
26
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27#include <clocksource/arm_arch_timer.h>
28
29#define USECS_TO_CYCLES(time_usecs) \
30 xloops_to_cycles((time_usecs) * 0x10C7UL)
31
32static inline unsigned long xloops_to_cycles(unsigned long xloops)
33{
34 return (xloops * loops_per_jiffy * HZ) >> 32;
35}
36
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37void __delay(unsigned long cycles)
38{
39 cycles_t start = get_cycles();
40
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41 if (arch_timer_evtstrm_available()) {
42 const cycles_t timer_evt_period =
43 USECS_TO_CYCLES(ARCH_TIMER_EVT_STREAM_PERIOD_US);
44
45 while ((get_cycles() - start + timer_evt_period) < cycles)
46 wfe();
47 }
48
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49 while ((get_cycles() - start) < cycles)
50 cpu_relax();
51}
52EXPORT_SYMBOL(__delay);
53
54inline void __const_udelay(unsigned long xloops)
55{
7b77452e 56 __delay(xloops_to_cycles(xloops));
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57}
58EXPORT_SYMBOL(__const_udelay);
59
60void __udelay(unsigned long usecs)
61{
62 __const_udelay(usecs * 0x10C7UL); /* 2**32 / 1000000 (rounded up) */
63}
64EXPORT_SYMBOL(__udelay);
65
66void __ndelay(unsigned long nsecs)
67{
68 __const_udelay(nsecs * 0x5UL); /* 2**32 / 1000000000 (rounded up) */
69}
70EXPORT_SYMBOL(__ndelay);