| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 1995-2004 Russell King |
| 3 | * |
| 4 | * Delay routines, using a pre-computed "loops_per_second" value. |
| 5 | */ |
| 6 | #ifndef __ASM_ARM_DELAY_H |
| 7 | #define __ASM_ARM_DELAY_H |
| 8 | |
| 9 | extern void __delay(int loops); |
| 10 | |
| 11 | /* |
| 12 | * This function intentionally does not exist; if you see references to |
| 13 | * it, it means that you're calling udelay() with an out of range value. |
| 14 | * |
| 15 | * With currently imposed limits, this means that we support a max delay |
| 16 | * of 2000us and 671 bogomips |
| 17 | */ |
| 18 | extern void __bad_udelay(void); |
| 19 | |
| 20 | /* |
| 21 | * division by multiplication: you don't have to worry about |
| 22 | * loss of precision. |
| 23 | * |
| 24 | * Use only for very small delays ( < 1 msec). Should probably use a |
| 25 | * lookup table, really, as the multiplications take much too long with |
| 26 | * short delays. This is a "reasonable" implementation, though (and the |
| 27 | * first constant multiplications gets optimized away if the delay is |
| 28 | * a constant) |
| 29 | */ |
| 30 | extern void __udelay(unsigned long usecs); |
| 31 | extern void __const_udelay(unsigned long); |
| 32 | |
| 33 | #define MAX_UDELAY_MS 2 |
| 34 | |
| 35 | #define udelay(n) \ |
| 36 | (__builtin_constant_p(n) ? \ |
| 37 | ((n) > (MAX_UDELAY_MS * 1000) ? __bad_udelay() : \ |
| 38 | __const_udelay((n) * 0x68dbul)) : \ |
| 39 | __udelay(n)) |
| 40 | |
| 41 | #endif /* defined(_ARM_DELAY_H) */ |
| 42 | |