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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.
*/
#include <timer.h>
#include <gpxe/nvs/threewire.h>
/** @file
*
* Three-wire serial interface
*
*/
/**
* Read from a three-wire device
*
* @v three Three-wire interface
* @v address Address
* @ret data Data
*/
unsigned long threewire_read ( struct threewire *three,
unsigned long address ) {
struct threewire_operations *ops = three->ops;
unsigned long command;
unsigned long data;
int i;
ops->setcs ( three, 1 );
/* Send command and address */
command = threewire_cmd_read ( three, address );
for ( i = ( threewire_cmd_len ( three ) - 1 ) ; i >= 0 ; i-- ) {
ops->setdi ( three, ( command >> i ) & 0x1 );
udelay ( three->udelay );
ops->setsk ( three, 1 );
udelay ( three->udelay );
ops->setsk ( three, 0 );
}
/* Read back data */
data = 0;
for ( i = three->datasize ; i ; i-- ) {
udelay ( three->udelay );
ops->setsk ( three, 1 );
udelay ( three->udelay );
data <<= 1;
data |= ops->getdo ( three );
ops->setsk ( three, 0 );
}
ops->setcs ( three, 0 );
return data;
}
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