Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 1993, 2000 Linus Torvalds |
| 3 | * |
| 4 | * Delay routines, using a pre-computed "loops_per_jiffy" value. |
| 5 | */ |
| 6 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 7 | #include <linux/module.h> |
| 8 | #include <linux/sched.h> /* for udelay's use of smp_processor_id */ |
| 9 | #include <asm/param.h> |
| 10 | #include <asm/smp.h> |
| 11 | #include <linux/delay.h> |
| 12 | |
| 13 | /* |
| 14 | * Use only for very small delays (< 1 msec). |
| 15 | * |
| 16 | * The active part of our cycle counter is only 32-bits wide, and |
| 17 | * we're treating the difference between two marks as signed. On |
| 18 | * a 1GHz box, that's about 2 seconds. |
| 19 | */ |
| 20 | |
| 21 | void |
| 22 | __delay(int loops) |
| 23 | { |
| 24 | int tmp; |
| 25 | __asm__ __volatile__( |
| 26 | " rpcc %0\n" |
| 27 | " addl %1,%0,%1\n" |
| 28 | "1: rpcc %0\n" |
| 29 | " subl %1,%0,%0\n" |
| 30 | " bgt %0,1b" |
| 31 | : "=&r" (tmp), "=r" (loops) : "1"(loops)); |
| 32 | } |
Sudip Mukherjee | 14b97de | 2015-09-17 16:01:49 -0700 | [diff] [blame] | 33 | EXPORT_SYMBOL(__delay); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 34 | |
| 35 | #ifdef CONFIG_SMP |
| 36 | #define LPJ cpu_data[smp_processor_id()].loops_per_jiffy |
| 37 | #else |
| 38 | #define LPJ loops_per_jiffy |
| 39 | #endif |
| 40 | |
| 41 | void |
| 42 | udelay(unsigned long usecs) |
| 43 | { |
| 44 | usecs *= (((unsigned long)HZ << 32) / 1000000) * LPJ; |
| 45 | __delay((long)usecs >> 32); |
| 46 | } |
| 47 | EXPORT_SYMBOL(udelay); |
| 48 | |
| 49 | void |
| 50 | ndelay(unsigned long nsecs) |
| 51 | { |
| 52 | nsecs *= (((unsigned long)HZ << 32) / 1000000000) * LPJ; |
| 53 | __delay((long)nsecs >> 32); |
| 54 | } |
| 55 | EXPORT_SYMBOL(ndelay); |