170 lines
3.5 KiB
C
170 lines
3.5 KiB
C
/*
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* Copyright (C) 2003 PMC-Sierra Inc.
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* Author: Manish Lachwani (lachwani@pmc-sierra.com)
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
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* NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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/*
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* Description:
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*
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* This code reads the ATMEL 24CXX EEPROM. The PMC-Sierra Yosemite board uses the ATMEL
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* 24C32/24C64 which uses two byte addressing as compared to 24C16. Note that this program
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* uses the serial port like /dev/ttyS0, to communicate with the EEPROM. Hence, you are
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* expected to have a connectivity from the EEPROM to the serial port. This program does
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* __not__ communicate using the I2C protocol
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*/
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#include "atmel_read_eeprom.h"
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static void delay(int delay)
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{
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while (delay--);
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}
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static void send_bit(unsigned char bit)
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{
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scl_lo;
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delay(TXX);
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if (bit)
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sda_hi;
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else
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sda_lo;
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delay(TXX);
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scl_hi;
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delay(TXX);
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}
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static void send_ack(void)
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{
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send_bit(0);
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}
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static void send_byte(unsigned char byte)
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{
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int i = 0;
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for (i = 7; i >= 0; i--)
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send_bit((byte >> i) & 0x01);
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}
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static void send_start(void)
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{
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sda_hi;
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delay(TXX);
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scl_hi;
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delay(TXX);
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sda_lo;
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delay(TXX);
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}
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static void send_stop(void)
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{
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sda_lo;
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delay(TXX);
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scl_hi;
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delay(TXX);
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sda_hi;
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delay(TXX);
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}
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static void do_idle(void)
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{
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sda_hi;
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scl_hi;
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vcc_off;
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}
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static int recv_bit(void)
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{
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int status;
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scl_lo;
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delay(TXX);
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sda_hi;
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delay(TXX);
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scl_hi;
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delay(TXX);
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return 1;
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}
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static unsigned char recv_byte(void) {
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int i;
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unsigned char byte=0;
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for (i=7;i>=0;i--)
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byte |= (recv_bit() << i);
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return byte;
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}
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static int recv_ack(void)
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{
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unsigned int ack;
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ack = (unsigned int)recv_bit();
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scl_lo;
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if (ack) {
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do_idle();
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printk(KERN_ERR "Error reading the Atmel 24C32/24C64 EEPROM\n");
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return -1;
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}
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return ack;
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}
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/*
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* This function does the actual read of the EEPROM. It needs the buffer into which the
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* read data is copied, the size of the EEPROM being read and the buffer size
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*/
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int read_eeprom(char *buffer, int eeprom_size, int size)
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{
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int i = 0, err;
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send_start();
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send_byte(W_HEADER);
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recv_ack();
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/* EEPROM with size of more than 2K need two byte addressing */
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if (eeprom_size > 2048) {
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send_byte(0x00);
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recv_ack();
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}
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send_start();
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send_byte(R_HEADER);
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err = recv_ack();
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if (err == -1)
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return err;
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for (i = 0; i < size; i++) {
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*buffer++ = recv_byte();
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send_ack();
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}
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/* Note : We should do some check if the buffer contains correct information */
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send_stop();
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}
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