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/* -*- c++ -*- */

/* $Id: i2c.c 395 2011-07-17 22:02:55Z mueller $ */

/*-----------------------------------------------------------------------------

 * I2C read/write functions for FX2

 *-----------------------------------------------------------------------------

 * Code taken from USRP2 firmware (GNU Radio Project), version 3.0.2,

 * Copyright 2003 Free Software Foundation, Inc.

 *-----------------------------------------------------------------------------

 * This code is part of usbjtag. usbjtag 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. usbjtag 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 in the file

 * COPYING; if not, write to the Free Software Foundation, Inc., 51 Franklin

 * St, Fifth Floor, Boston, MA  02110-1301  USA

 *-----------------------------------------------------------------------------

 */

#include "i2c.h"

#include "fx2regs.h"

#include <string.h>

// issue a stop bus cycle and wait for completion

// returns non-zero if successful, else 0

unsigned char

i2c_read (unsigned char addr, xdata unsigned char *buf, unsigned char len)

{

  volatile unsigned char        junk;

  if (len == 0)                  // reading zero bytes always works

    return 1;

  while (I2CS & bmSTOP)         // wait for stop to clear

    ;

  I2CS = bmSTART;

  I2DAT = (addr << 1) | 1;      // write address and direction (1's the read bit)

  while ((I2CS & bmDONE) == 0)

    ;

  if ((I2CS & bmBERR) || (I2CS & bmACK) == 0)    // no device answered...

    goto fail;

  if (len == 1)

    I2CS |= bmLASTRD;

  junk = I2DAT;                 // trigger the first read cycle

  while (--len != 0){

    while ((I2CS & bmDONE) == 0)

      ;

    if (I2CS & bmBERR)

      goto fail;

    if (len == 1)

      I2CS |= bmLASTRD;

    *buf++ = I2DAT;             // get data, trigger another read

  }

  // wait for final byte

  while ((I2CS & bmDONE) == 0)

    ;

  if (I2CS & bmBERR)

    goto fail;

  I2CS |= bmSTOP;

  *buf = I2DAT;

  return 1;

 fail:

  I2CS |= bmSTOP;

  return 0;

}

// returns non-zero if successful, else 0

unsigned char

i2c_write (unsigned char addr, xdata const unsigned char *buf, unsigned char len)

{

  while (I2CS & bmSTOP)         // wait for stop to clear

    ;

  I2CS = bmSTART;

  I2DAT = (addr << 1) | 0;       // write address and direction (0's the write bit)

  while ((I2CS & bmDONE) == 0)

    ;

  if ((I2CS & bmBERR) || (I2CS & bmACK) == 0)    // no device answered...

    goto fail;

  while (len > 0){

    I2DAT = *buf++;

    len--;

    while ((I2CS & bmDONE) == 0)

      ;

    if ((I2CS & bmBERR) || (I2CS & bmACK) == 0)  // no device answered...

      goto fail;

  }

  I2CS |= bmSTOP;

  return 1;

 fail:

  I2CS |= bmSTOP;

  return 0;

}