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Added sketch of bit-bashing interface common code
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Michael Brown
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Jun 8, 2006
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/* | ||
* Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>. | ||
* | ||
* This program is free software; you can redistribute it and/or | ||
* modify it under the terms of the GNU General Public License as | ||
* published by the Free Software Foundation; either version 2 of the | ||
* License, or any later version. | ||
* | ||
* This program is distributed in the hope that it will be useful, but | ||
* WITHOUT ANY WARRANTY; without even the implied warranty of | ||
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | ||
* General Public License for more details. | ||
* | ||
* You should have received a copy of the GNU General Public License | ||
* along with this program; if not, write to the Free Software | ||
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | ||
*/ | ||
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#include <timer.h> | ||
#include <gpxe/bitbash.h> | ||
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/** @file | ||
* | ||
* Bit-bashing interfaces | ||
* | ||
*/ | ||
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/** | ||
* Set/clear output bit | ||
* | ||
* @v basher Bit-bashing interface | ||
* @v bit_id Bit number | ||
* @v data Value to write | ||
* | ||
* If @c data is 0, a logic 0 will be written. If @c data is | ||
* non-zero, a logic 1 will be written. | ||
*/ | ||
void write_bit ( struct bit_basher *basher, unsigned int bit_id, | ||
unsigned long data ) { | ||
basher->write ( basher, bit_id, ( data ? -1UL : 0 ) ); | ||
udelay ( basher->udelay ); | ||
} | ||
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/** | ||
* Read input bit | ||
* | ||
* @v basher Bit-bashing interface | ||
* @v bit_id Bit number | ||
* @ret data Value read | ||
* | ||
* @c data will always be either 0 or 1. | ||
*/ | ||
int read_bit ( struct bit_basher *basher, unsigned int bit_id ) { | ||
return ( basher->read ( basher, bit_id ) ? 1 : 0 ); | ||
} |
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#ifndef _GPXE_BITBASH_H | ||
#define _GPXE_BITBASH_H | ||
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/** @file | ||
* | ||
* Bit-bashing interfaces | ||
* | ||
*/ | ||
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/** A bit-bashing interface */ | ||
struct bit_basher { | ||
/** | ||
* Set/clear output bit | ||
* | ||
* @v basher Bit-bashing interface | ||
* @v bit_id Bit number | ||
* @v data Value to write | ||
* | ||
* @c data will be 0 if a logic 0 should be written (i.e. the | ||
* bit should be cleared), or -1UL if a logic 1 should be | ||
* written (i.e. the bit should be set). This is done so that | ||
* the method may simply binary-AND @c data with the | ||
* appropriate bit mask. | ||
*/ | ||
void ( * write ) ( struct bit_basher *basher, unsigned int bit_id, | ||
unsigned long data ); | ||
/** | ||
* Read input bit | ||
* | ||
* @v basher Bit-bashing interface | ||
* @v bit_id Bit number | ||
* @ret zero Input is a logic 0 | ||
* @ret non-zero Input is a logic 1 | ||
*/ | ||
int ( * read ) ( struct bit_basher *basher, unsigned int bit_id ); | ||
/** Delay between subsequent calls to write(), in microseconds */ | ||
unsigned int udelay; | ||
}; | ||
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extern void write_bit ( struct bit_basher *basher, unsigned int bit_id, | ||
unsigned long data ); | ||
extern int read_bit ( struct bit_basher *basher, unsigned int bit_id ); | ||
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#endif /* _GPXE_BITBASH_H */ |