arch/arm/include/asm/delay.h

/*
 * Copyright (C) 1995-2004 Russell King
 *
 * Delay routines, using a pre-computed "loops_per_second" value.
 */
#ifndef __ASM_ARM_DELAY_H
#define __ASM_ARM_DELAY_H

#include <asm/memory.h>
#include <asm/param.h>	

#define MAX_UDELAY_MS	2
#define UDELAY_MULT	((UL(2199023) * HZ) >> 11)
#define UDELAY_SHIFT	30

#ifndef __ASSEMBLY__

struct delay_timer {
	unsigned long (*read_current_timer)(void);
	unsigned long freq;
};

extern struct arm_delay_ops {
	void (*delay)(unsigned long);
	void (*const_udelay)(unsigned long);
	void (*udelay)(unsigned long);
} arm_delay_ops;

#define __delay(n)		arm_delay_ops.delay(n)

extern void __bad_udelay(void);

#define __udelay(n)		arm_delay_ops.udelay(n)
#define __const_udelay(n)	arm_delay_ops.const_udelay(n)

#define udelay(n)							\
	(__builtin_constant_p(n) ?					\
	  ((n) > (MAX_UDELAY_MS * 1000) ? __bad_udelay() :		\
			__const_udelay((n) * UDELAY_MULT)) :		\
	  __udelay(n))

extern void __loop_delay(unsigned long loops);
extern void __loop_udelay(unsigned long usecs);
extern void __loop_const_udelay(unsigned long);

#define ARCH_HAS_READ_CURRENT_TIMER
extern void register_current_timer_delay(const struct delay_timer *timer);

#endif 

#endif