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 #include <asm/param.h> /* HZ */
10
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
18 * of 2000us. Further limits: HZ<=1000 and bogomips<=3355
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
37 #define udelay(n) \
38 (__builtin_constant_p(n) ? \
39 ((n) > (MAX_UDELAY_MS * 1000) ? __bad_udelay() : \
40 __const_udelay((n) * ((2199023U*HZ)>>11))) : \
41 __udelay(n))
42
43 #endif /* defined(_ARM_DELAY_H) */
44
45
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