53 lines
1.5 KiB
C
53 lines
1.5 KiB
C
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/*
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* linux/arch/unicore32/include/asm/delay.h
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*
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* Code specific to PKUnity SoC and UniCore ISA
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*
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* Copyright (C) 2001-2010 GUAN Xue-tao
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Delay routines, using a pre-computed "loops_per_second" value.
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*/
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#ifndef __UNICORE_DELAY_H__
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#define __UNICORE_DELAY_H__
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#include <asm/param.h> /* HZ */
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extern void __delay(int loops);
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/*
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* This function intentionally does not exist; if you see references to
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* it, it means that you're calling udelay() with an out of range value.
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*
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* With currently imposed limits, this means that we support a max delay
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* of 2000us. Further limits: HZ<=1000 and bogomips<=3355
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*/
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extern void __bad_udelay(void);
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/*
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* division by multiplication: you don't have to worry about
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* loss of precision.
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*
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* Use only for very small delays ( < 1 msec). Should probably use a
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* lookup table, really, as the multiplications take much too long with
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* short delays. This is a "reasonable" implementation, though (and the
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* first constant multiplications gets optimized away if the delay is
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* a constant)
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*/
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extern void __udelay(unsigned long usecs);
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extern void __const_udelay(unsigned long);
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#define MAX_UDELAY_MS 2
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#define udelay(n) \
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(__builtin_constant_p(n) ? \
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((n) > (MAX_UDELAY_MS * 1000) ? __bad_udelay() : \
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__const_udelay((n) * ((2199023U*HZ)>>11))) : \
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__udelay(n))
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#endif /* __UNICORE_DELAY_H__ */
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