Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

/*

 *  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 then 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();

}