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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Precise Delay Loops for S390
4 *
5 * Copyright IBM Corp. 1999, 2008
6 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>,
7 * Heiko Carstens <heiko.carstens@de.ibm.com>,
8 */
9
10#include <linux/sched.h>
11#include <linux/delay.h>
12#include <linux/timex.h>
13#include <linux/export.h>
14#include <linux/irqflags.h>
15#include <linux/interrupt.h>
16#include <linux/jump_label.h>
17#include <linux/irq.h>
18#include <asm/vtimer.h>
19#include <asm/div64.h>
20#include <asm/idle.h>
21
22void __delay(unsigned long loops)
23{
24 /*
25 * To end the bloody studid and useless discussion about the
26 * BogoMips number I took the liberty to define the __delay
27 * function in a way that that resulting BogoMips number will
28 * yield the megahertz number of the cpu. The important function
29 * is udelay and that is done using the tod clock. -- martin.
30 */
31 asm volatile("0: brct %0,0b" : : "d" ((loops/2) + 1));
32}
33EXPORT_SYMBOL(__delay);
34
35static void delay_loop(unsigned long delta)
36{
37 unsigned long end;
38
39 end = get_tod_clock_monotonic() + delta;
40 while (!tod_after(get_tod_clock_monotonic(), end))
41 cpu_relax();
42}
43
44void __udelay(unsigned long usecs)
45{
46 delay_loop(usecs << 12);
47}
48EXPORT_SYMBOL(__udelay);
49
50void __ndelay(unsigned long nsecs)
51{
52 nsecs <<= 9;
53 do_div(nsecs, 125);
54 delay_loop(nsecs);
55}
56EXPORT_SYMBOL(__ndelay);