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/*
* arch/mips/pmc-sierra/yosemite/atmel_read_eeprom.c
*
* Copyright (C) 2003 PMC-Sierra Inc.
* Author: Manish Lachwani (lachwani@pmc-sierra.com)
*
* 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 (at your
* option) any later version.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
* NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* 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.
*/
/*
* Description:
*
* This code reads the ATMEL 24CXX EEPROM. The PMC-Sierra Yosemite board uses the ATMEL
* 24C32/24C64 which uses two byte addressing as compared to 24C16. Note that this program
* uses the serial port like /dev/ttyS0, to communicate with the EEPROM. Hence, you are
* expected to have a connectivity from the EEPROM to the serial port. This program does
* __not__ communicate using the I2C protocol
*/
#include "atmel_read_eeprom.h"
static void delay(int delay)
{
while (delay--);
}
static void send_bit(unsigned char bit)
{
scl_lo;
delay(TXX);
if (bit)
sda_hi;
else
sda_lo;
delay(TXX);
scl_hi;
delay(TXX);
}
static void send_ack(void)
{
send_bit(0);
}
static void send_byte(unsigned char byte)
{
int i = 0;
for (i = 7; i >= 0; i--)
send_bit((byte >> i) & 0x01);
}
static void send_start(void)
{
sda_hi;
delay(TXX);
scl_hi;
delay(TXX);
sda_lo;
delay(TXX);
}
static void send_stop(void)
{
sda_lo;
delay(TXX);
scl_hi;
delay(TXX);
sda_hi;
delay(TXX);
}
static void do_idle(void)
{
sda_hi;
scl_hi;
vcc_off;
}
static int recv_bit(void)
{
int status;
scl_lo;
delay(TXX);
sda_hi;
delay(TXX);
scl_hi;
delay(TXX);
return 1;
}
static unsigned char recv_byte(void) {
int i;
unsigned char byte=0;
for (i=7;i>=0;i--)
byte |= (recv_bit() << i);
return byte;
}
static int recv_ack(void)
{
unsigned int ack;
ack = (unsigned int)recv_bit();
scl_lo;
if (ack) {
do_idle();
printk(KERN_ERR "Error reading the Atmel 24C32/24C64 EEPROM \n");
return -1;
}
return ack;
}
/*
* This function does the actual read of the EEPROM. It needs the buffer into which the
* read data is copied, the size of the EEPROM being read and the buffer size
*/
int read_eeprom(char *buffer, int eeprom_size, int size)
{
int i = 0, err;
send_start();
send_byte(W_HEADER);
recv_ack();
/* EEPROM with size of more than 2K need two byte addressing */
if (eeprom_size > 2048) {
send_byte(0x00);
recv_ack();
}
send_start();
send_byte(R_HEADER);
err = recv_ack();
if (err == -1)
return err;
for (i = 0; i < size; i++) {
*buffer++ = recv_byte();
send_ack();
}
/* Note : We should do some check if the buffer contains correct information */
send_stop();
}
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