Subversion Repositories or1k

/*

 *  linux/include/asm-arm/delay.h

 *

 *  Copyright (C) 1995-2003 Russell King

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 *

 *  Delay routines, using a pre-computed "loops_per_second" value.

 */

#ifndef __ASM_ARM_DELAY_H

#define __ASM_ARM_DELAY_H

/*

 * Division by multiplication and shifts.

 *

 *  We want the number of loops to complete, where loops is:

 *      (us * (HZ * loops_per_jiffy)) / 10^6

 *  or

 *      (ns * (HZ * loops_per_jiffy)) / 10^9

 *

 *  Since we don't want to do long division, we multiply both numerator

 *  and denominator by (2^28 / 10^6):

 *

 *      (us * (2^28 / 10^6) * HZ * loops_per_jiffy) / 2^28

 *

 *  =>  (us * (2^28 * HZ / 10^6) * loops_per_jiffy) / 2^28

 *

 *  ~>  (((us * (2^28 * HZ / 10^6)) / 2^11) * (loops_per_jiffy / 2^12)) / 2^5

 *         (for large loops_per_jiffy >> 2^12)

 *

 *  Note: maximum loops_per_jiffy = 67108863 (bogomips = 1342.18)

 *        minimum loops_per_jiffy = 20000 (bogomips = 0.4)

 *

 * Note: we rely on HZ = 100.

 */

#define UDELAY_FACTOR   26843

#define NDELAY_FACTOR   27

#ifndef __ASSEMBLY__

extern void __bad_udelay(void); /* intentional errors */

extern void __bad_ndelay(void); /* intentional errors */

extern void __delay(unsigned long loops);

extern void __udelay(unsigned long usecs);

extern void __ndelay(unsigned long nsecs);

extern void __const_delay(unsigned long units);

#define udelay(n)                                                       \

        (__builtin_constant_p(n) ?                                      \

                ((n) > 20000 ? __bad_udelay()                           \

                             : __const_delay((n) * UDELAY_FACTOR))      \

                                 : __udelay(n))

#define ndelay(n)                                                       \

        (__builtin_constant_p(n) ?                                      \

                ((n) > 20000 ? __bad_ndelay()                           \

                             : __const_delay((n) * NDELAY_FACTOR))      \

                                 : __ndelay(n))

#endif

#endif /* defined(_ARM_DELAY_H) */