1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * Copyright (C) 1993, 2000 Linus Torvalds
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Delay routines, using a pre-computed "loops_per_jiffy" value.
6*4882a593Smuzhiyun */
7*4882a593Smuzhiyun
8*4882a593Smuzhiyun #include <linux/module.h>
9*4882a593Smuzhiyun #include <linux/sched.h> /* for udelay's use of smp_processor_id */
10*4882a593Smuzhiyun #include <asm/param.h>
11*4882a593Smuzhiyun #include <asm/smp.h>
12*4882a593Smuzhiyun #include <linux/delay.h>
13*4882a593Smuzhiyun
14*4882a593Smuzhiyun /*
15*4882a593Smuzhiyun * Use only for very small delays (< 1 msec).
16*4882a593Smuzhiyun *
17*4882a593Smuzhiyun * The active part of our cycle counter is only 32-bits wide, and
18*4882a593Smuzhiyun * we're treating the difference between two marks as signed. On
19*4882a593Smuzhiyun * a 1GHz box, that's about 2 seconds.
20*4882a593Smuzhiyun */
21*4882a593Smuzhiyun
22*4882a593Smuzhiyun void
__delay(int loops)23*4882a593Smuzhiyun __delay(int loops)
24*4882a593Smuzhiyun {
25*4882a593Smuzhiyun int tmp;
26*4882a593Smuzhiyun __asm__ __volatile__(
27*4882a593Smuzhiyun " rpcc %0\n"
28*4882a593Smuzhiyun " addl %1,%0,%1\n"
29*4882a593Smuzhiyun "1: rpcc %0\n"
30*4882a593Smuzhiyun " subl %1,%0,%0\n"
31*4882a593Smuzhiyun " bgt %0,1b"
32*4882a593Smuzhiyun : "=&r" (tmp), "=r" (loops) : "1"(loops));
33*4882a593Smuzhiyun }
34*4882a593Smuzhiyun EXPORT_SYMBOL(__delay);
35*4882a593Smuzhiyun
36*4882a593Smuzhiyun #ifdef CONFIG_SMP
37*4882a593Smuzhiyun #define LPJ cpu_data[smp_processor_id()].loops_per_jiffy
38*4882a593Smuzhiyun #else
39*4882a593Smuzhiyun #define LPJ loops_per_jiffy
40*4882a593Smuzhiyun #endif
41*4882a593Smuzhiyun
42*4882a593Smuzhiyun void
udelay(unsigned long usecs)43*4882a593Smuzhiyun udelay(unsigned long usecs)
44*4882a593Smuzhiyun {
45*4882a593Smuzhiyun usecs *= (((unsigned long)HZ << 32) / 1000000) * LPJ;
46*4882a593Smuzhiyun __delay((long)usecs >> 32);
47*4882a593Smuzhiyun }
48*4882a593Smuzhiyun EXPORT_SYMBOL(udelay);
49*4882a593Smuzhiyun
50*4882a593Smuzhiyun void
ndelay(unsigned long nsecs)51*4882a593Smuzhiyun ndelay(unsigned long nsecs)
52*4882a593Smuzhiyun {
53*4882a593Smuzhiyun nsecs *= (((unsigned long)HZ << 32) / 1000000000) * LPJ;
54*4882a593Smuzhiyun __delay((long)nsecs >> 32);
55*4882a593Smuzhiyun }
56*4882a593Smuzhiyun EXPORT_SYMBOL(ndelay);
57