internalflashc.nc

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// $Id: InternalFlashC.nc,v 1.1 2005/07/22 17:40:10 jwhui Exp $

/*									tab:4
 *
 *
 * "Copyright (c) 2000-2004 The Regents of the University  of California.  
 * All rights reserved.
 *
 * Permission to use, copy, modify, and distribute this software and its
 * documentation for any purpose, without fee, and without written agreement is
 * hereby granted, provided that the above copyright notice, the following
 * two paragraphs and the author appear in all copies of this software.
 * 
 * IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR
 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT
 * OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF
 * CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 * THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
 * ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATION TO
 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS."
 *
 */

/**
 * InternalFlashC.nc - Internal flash implementation for telos msp
 * platform. On the msp, the flash must first be erased before a value
 * can be written. However, the msp can only erase the flash at a
 * segment granularity (128 bytes for the information section). This
 * module allows transparent read/write of individual bytes to the
 * information section by dynamically switching between the two
 * provided segments in the information section.
 *
 * Valid address range is 0x1000 - 0x107E (0x107F is used to store the
 * version number of the information segment).
 *
 * @author Jonathan Hui <[e-mail]>
 */

includes InternalFlash;

module InternalFlashC {
  provides interface InternalFlash;
}

implementation {

  enum {
    IFLASH_OFFSET     = 0x1000,
    IFLASH_SIZE       = 128,
    IFLASH_SEG0_VNUM_ADDR = 0x107f,
    IFLASH_SEG1_VNUM_ADDR = 0x10ff,
    IFLASH_INVALID_VNUM = -1,
  };

  uint8_t chooseSegment() {
    int8_t vnum0 = *(int8_t*)IFLASH_SEG0_VNUM_ADDR;
    int8_t vnum1 = *(int8_t*)IFLASH_SEG1_VNUM_ADDR;
    if (vnum0 == IFLASH_INVALID_VNUM)
      return 1;
    else if (vnum1 == IFLASH_INVALID_VNUM)
      return 0;
    return ( (int8_t)(vnum0 - vnum1) < 0 );
  }

  command result_t InternalFlash.write(void* addr, void* buf, uint16_t size) {

    volatile int8_t *newPtr;
    int8_t *oldPtr;
    int8_t *bufPtr = (int8_t*)buf;
    int8_t version;
    uint16_t i;

    addr += IFLASH_OFFSET;
    newPtr = oldPtr = (int8_t*)IFLASH_OFFSET;
    if (chooseSegment()) {
      oldPtr += IFLASH_SIZE;
    }
    else {
      addr += IFLASH_SIZE;
      newPtr += IFLASH_SIZE;
    }

    FCTL2 = FWKEY + FSSEL1 + FN2;
    FCTL3 = FWKEY;
    FCTL1 = FWKEY + ERASE;
    *newPtr = 0;
    FCTL1 = FWKEY + WRT;
    
    for ( i = 0; i < IFLASH_SIZE-1; i++, newPtr++, oldPtr++ ) {
      if ((uint16_t)newPtr < (uint16_t)addr || (uint16_t)addr+size <= (uint16_t)newPtr)
	*newPtr = *oldPtr;
      else
	*newPtr = *bufPtr++;
    }
    version = *oldPtr + 1;
    if (version == IFLASH_INVALID_VNUM)
      version++;
    *newPtr = version;
    
    FCTL1 = FWKEY;
    FCTL3 = FWKEY + LOCK;

    return SUCCESS;

  }

  command result_t InternalFlash.read(void* addr, void* buf, uint16_t size) {

    addr += IFLASH_OFFSET;
    if (chooseSegment())
      addr += IFLASH_SIZE;

    memcpy(buf, addr, size);

    return SUCCESS;

  }

}