1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * Copyright (C) 1993, 2000 Linus Torvalds |
4 | * |
5 | * Delay routines, using a pre-computed "loops_per_jiffy" value. |
6 | */ |
7 | |
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 | } |
34 | EXPORT_SYMBOL(__delay); |
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); |
57 | |