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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
Will Deacond0a533b2012-07-06 15:47:17 +01009#include <asm/memory.h>
Peter Teichmann6d4518d2006-03-20 17:10:09 +000010#include <asm/param.h> /* HZ */
11
Will Deacond0a533b2012-07-06 15:47:17 +010012#define MAX_UDELAY_MS 2
13#define UDELAY_MULT ((UL(2199023) * HZ) >> 11)
14#define UDELAY_SHIFT 30
15
16#ifndef __ASSEMBLY__
17
Jonathan Austin56942fe2012-09-21 18:51:44 +010018struct delay_timer {
19 unsigned long (*read_current_timer)(void);
20 unsigned long freq;
21};
22
Will Deacond0a533b2012-07-06 15:47:17 +010023extern struct arm_delay_ops {
24 void (*delay)(unsigned long);
25 void (*const_udelay)(unsigned long);
26 void (*udelay)(unsigned long);
27} arm_delay_ops;
28
29#define __delay(n) arm_delay_ops.delay(n)
Linus Torvalds1da177e2005-04-16 15:20:36 -070030
31/*
32 * This function intentionally does not exist; if you see references to
33 * it, it means that you're calling udelay() with an out of range value.
34 *
35 * With currently imposed limits, this means that we support a max delay
Peter Teichmann6d4518d2006-03-20 17:10:09 +000036 * of 2000us. Further limits: HZ<=1000 and bogomips<=3355
Linus Torvalds1da177e2005-04-16 15:20:36 -070037 */
38extern void __bad_udelay(void);
39
40/*
41 * division by multiplication: you don't have to worry about
42 * loss of precision.
43 *
Will Deacond0a533b2012-07-06 15:47:17 +010044 * Use only for very small delays ( < 2 msec). Should probably use a
Linus Torvalds1da177e2005-04-16 15:20:36 -070045 * lookup table, really, as the multiplications take much too long with
46 * short delays. This is a "reasonable" implementation, though (and the
47 * first constant multiplications gets optimized away if the delay is
48 * a constant)
49 */
Will Deacond0a533b2012-07-06 15:47:17 +010050#define __udelay(n) arm_delay_ops.udelay(n)
51#define __const_udelay(n) arm_delay_ops.const_udelay(n)
Linus Torvalds1da177e2005-04-16 15:20:36 -070052
Peter Teichmann6d4518d2006-03-20 17:10:09 +000053#define udelay(n) \
54 (__builtin_constant_p(n) ? \
55 ((n) > (MAX_UDELAY_MS * 1000) ? __bad_udelay() : \
Will Deacond0a533b2012-07-06 15:47:17 +010056 __const_udelay((n) * UDELAY_MULT)) : \
Linus Torvalds1da177e2005-04-16 15:20:36 -070057 __udelay(n))
58
Will Deacond0a533b2012-07-06 15:47:17 +010059/* Loop-based definitions for assembly code. */
60extern void __loop_delay(unsigned long loops);
61extern void __loop_udelay(unsigned long usecs);
62extern void __loop_const_udelay(unsigned long);
63
Jonathan Austin56942fe2012-09-21 18:51:44 +010064/* Delay-loop timer registration. */
65#define ARCH_HAS_READ_CURRENT_TIMER
66extern void register_current_timer_delay(const struct delay_timer *timer);
67
Will Deacond0a533b2012-07-06 15:47:17 +010068#endif /* __ASSEMBLY__ */
69
Linus Torvalds1da177e2005-04-16 15:20:36 -070070#endif /* defined(_ARM_DELAY_H) */
71