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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
1da177e4 LT |
2 | /* |
3 | * Copyright (C) 1993, 2000 Linus Torvalds | |
4 | * | |
5 | * Delay routines, using a pre-computed "loops_per_jiffy" value. | |
6 | */ | |
7 | ||
1da177e4 LT |
8 | #include <linux/module.h> |
9 | #include <linux/sched.h> /* for udelay's use of smp_processor_id */ | |
10 | #include <asm/param.h> | |
11 | #include <asm/smp.h> | |
12 | #include <linux/delay.h> | |
13 | ||
14 | /* | |
15 | * Use only for very small delays (< 1 msec). | |
16 | * | |
17 | * The active part of our cycle counter is only 32-bits wide, and | |
18 | * we're treating the difference between two marks as signed. On | |
19 | * a 1GHz box, that's about 2 seconds. | |
20 | */ | |
21 | ||
22 | void | |
23 | __delay(int loops) | |
24 | { | |
25 | int tmp; | |
26 | __asm__ __volatile__( | |
27 | " rpcc %0\n" | |
28 | " addl %1,%0,%1\n" | |
29 | "1: rpcc %0\n" | |
30 | " subl %1,%0,%0\n" | |
31 | " bgt %0,1b" | |
32 | : "=&r" (tmp), "=r" (loops) : "1"(loops)); | |
33 | } | |
14b97ded | 34 | EXPORT_SYMBOL(__delay); |
1da177e4 LT |
35 | |
36 | #ifdef CONFIG_SMP | |
37 | #define LPJ cpu_data[smp_processor_id()].loops_per_jiffy | |
38 | #else | |
39 | #define LPJ loops_per_jiffy | |
40 | #endif | |
41 | ||
42 | void | |
43 | udelay(unsigned long usecs) | |
44 | { | |
45 | usecs *= (((unsigned long)HZ << 32) / 1000000) * LPJ; | |
46 | __delay((long)usecs >> 32); | |
47 | } | |
48 | EXPORT_SYMBOL(udelay); | |
49 | ||
50 | void | |
51 | ndelay(unsigned long nsecs) | |
52 | { | |
53 | nsecs *= (((unsigned long)HZ << 32) / 1000000000) * LPJ; | |
54 | __delay((long)nsecs >> 32); | |
55 | } | |
56 | EXPORT_SYMBOL(ndelay); |