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1da177e4 LT |
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 | ||
6d4518d7 PT |
9 | #include <asm/param.h> /* HZ */ |
10 | ||
1da177e4 LT |
11 | extern void __delay(int loops); |
12 | ||
13 | /* | |
14 | * This function intentionally does not exist; if you see references to | |
15 | * it, it means that you're calling udelay() with an out of range value. | |
16 | * | |
17 | * With currently imposed limits, this means that we support a max delay | |
6d4518d7 | 18 | * of 2000us. Further limits: HZ<=1000 and bogomips<=3355 |
1da177e4 LT |
19 | */ |
20 | extern void __bad_udelay(void); | |
21 | ||
22 | /* | |
23 | * division by multiplication: you don't have to worry about | |
24 | * loss of precision. | |
25 | * | |
26 | * Use only for very small delays ( < 1 msec). Should probably use a | |
27 | * lookup table, really, as the multiplications take much too long with | |
28 | * short delays. This is a "reasonable" implementation, though (and the | |
29 | * first constant multiplications gets optimized away if the delay is | |
30 | * a constant) | |
31 | */ | |
32 | extern void __udelay(unsigned long usecs); | |
33 | extern void __const_udelay(unsigned long); | |
34 | ||
35 | #define MAX_UDELAY_MS 2 | |
36 | ||
6d4518d7 PT |
37 | #define udelay(n) \ |
38 | (__builtin_constant_p(n) ? \ | |
39 | ((n) > (MAX_UDELAY_MS * 1000) ? __bad_udelay() : \ | |
40 | __const_udelay((n) * ((2199023U*HZ)>>11))) : \ | |
1da177e4 LT |
41 | __udelay(n)) |
42 | ||
43 | #endif /* defined(_ARM_DELAY_H) */ | |
44 |