77 lines
2.3 KiB
C
77 lines
2.3 KiB
C
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#ifndef _M68KNOMMU_DELAY_H
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#define _M68KNOMMU_DELAY_H
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/*
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* Copyright (C) 1994 Hamish Macdonald
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* Copyright (C) 2004 Greg Ungerer <gerg@snapgear.com>
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*/
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#include <asm/param.h>
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static inline void __delay(unsigned long loops)
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{
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#if defined(CONFIG_COLDFIRE)
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/* The coldfire runs this loop at significantly different speeds
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* depending upon long word alignment or not. We'll pad it to
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* long word alignment which is the faster version.
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* The 0x4a8e is of course a 'tstl %fp' instruction. This is better
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* than using a NOP (0x4e71) instruction because it executes in one
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* cycle not three and doesn't allow for an arbitary delay waiting
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* for bus cycles to finish. Also fp/a6 isn't likely to cause a
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* stall waiting for the register to become valid if such is added
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* to the coldfire at some stage.
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*/
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__asm__ __volatile__ ( ".balignw 4, 0x4a8e\n\t"
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"1: subql #1, %0\n\t"
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"jcc 1b"
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: "=d" (loops) : "0" (loops));
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#else
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__asm__ __volatile__ ( "1: subql #1, %0\n\t"
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"jcc 1b"
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: "=d" (loops) : "0" (loops));
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#endif
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}
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/*
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* Ideally we use a 32*32->64 multiply to calculate the number of
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* loop iterations, but the older standard 68k and ColdFire do not
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* have this instruction. So for them we have a clsoe approximation
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* loop using 32*32->32 multiplies only. This calculation based on
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* the ARM version of delay.
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*
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* We want to implement:
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*
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* loops = (usecs * 0x10c6 * HZ * loops_per_jiffy) / 2^32
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*/
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#define HZSCALE (268435456 / (1000000/HZ))
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extern unsigned long loops_per_jiffy;
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static inline void _udelay(unsigned long usecs)
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{
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#if defined(CONFIG_M68328) || defined(CONFIG_M68EZ328) || \
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defined(CONFIG_M68VZ328) || defined(CONFIG_M68360) || \
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defined(CONFIG_COLDFIRE)
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__delay((((usecs * HZSCALE) >> 11) * (loops_per_jiffy >> 11)) >> 6);
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#else
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unsigned long tmp;
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usecs *= 4295; /* 2**32 / 1000000 */
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__asm__ ("mulul %2,%0:%1"
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: "=d" (usecs), "=d" (tmp)
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: "d" (usecs), "1" (loops_per_jiffy*HZ));
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__delay(usecs);
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#endif
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}
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/*
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* Moved the udelay() function into library code, no longer inlined.
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* I had to change the algorithm because we are overflowing now on
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* the faster ColdFire parts. The code is a little bigger, so it makes
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* sense to library it.
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*/
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extern void udelay(unsigned long usecs);
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#endif /* defined(_M68KNOMMU_DELAY_H) */
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