at91flash.c

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/*! \file at91flash.c \brief Internal FLASH Write Routines for Atmel AT91. */
//*****************************************************************************
//
// File Name    : 'at91flash.c'
// Title        : Internal FLASH Write Routines for Atmel AT91
// Author       : Pascal Stang - Copyright (C) 2006
// Created      : 9/20/2006
// Revised      : 9/25/2006
// Version      : 0.1
// Target MCU   : Atmel AT91 series
// Editor Tabs  : 4
//
// This code is distributed under the GNU Public License
//      which can be found at http://www.gnu.org/licenses/gpl.txt
//
//*****************************************************************************

// system includes
#include "global.h"
#include "at91sam7s256.h"

// local includes
#include "at91flash.h"

void at91flashInit(void)
{
    // set cycles-per-microsecond
    //  as per datasheet,
    //  - NVM bits require a setting of F_CPU/1000
    //  - general flash write requires a setting of 1.5*F_CPU/1000
    // (here we're extra conservative setting clock cycles equal to 2us)
    AT91C_BASE_MC->MC_FMR = (((F_CPU*2/1000)<<16) & AT91C_MC_FMCN);
}

void at91flashWrite(uint32_t flashaddr, uint8_t* buffer, uint32_t len)
{
    int wrlen;

    // do automatic multi-page writes
    while(len)
    {
        // determine how many bytes to write
        wrlen = (len<AT91C_IFLASH_PAGE_SIZE)?(len):(AT91C_IFLASH_PAGE_SIZE);
        // write page
        at91flashWritePage(flashaddr, buffer, wrlen);
        // increment pointers
        flashaddr += wrlen;
        buffer += wrlen;
        // decrement remaining buffer size
        len -= wrlen;
    }
}

void at91flashWritePage(uint32_t flashaddr, uint8_t* buffer, uint32_t len)
{
    int pageword;
    unsigned long* wrptr = (unsigned long*)flashaddr;
    
    // do write cycle
    // copy data to flash location
    for(pageword=0; pageword<(len/4); pageword++)
    {
        // do the copy byte-wise because incoming buffer might not be word-aligned
        // NOTE: assuming little-endian source
        *wrptr++ = (buffer[3]<<24) | (buffer[2]<<16) | (buffer[1]<<8) | (buffer[0]<<0);
        buffer+=4;
    }
    // if the flash address does not begin on page boundary, then we do partial-page programming
    if( flashaddr & (AT91C_IFLASH_PAGE_SIZE-1) )
        AT91C_BASE_MC->MC_FMR |= AT91C_MC_NEBP;
    else
        AT91C_BASE_MC->MC_FMR &= ~AT91C_MC_NEBP;
    // write flash
    AT91C_BASE_MC->MC_FCR = (0x5A<<24) | (((flashaddr/AT91C_IFLASH_PAGE_SIZE)<<8)&AT91C_MC_PAGEN) | AT91C_MC_FCMD_START_PROG;
    // wait for flash done/ready
    while(!(AT91C_BASE_MC->MC_FSR & AT91C_MC_FRDY));
}

void at91flashErase(void)
{
    // erase flash
    AT91C_BASE_MC->MC_FCR = (0x5A<<24) | AT91C_MC_FCMD_ERASE_ALL;
    // wait for flash done/ready
    while(!(AT91C_BASE_MC->MC_FSR & AT91C_MC_FRDY));
}

int at91flashGetLock(uint32_t flashaddr)
{
    // mask flashaddr to size of flash
    flashaddr &= (AT91C_IFLASH_SIZE-1);
    // determine the lock state of a flash address/page
    if( AT91C_BASE_MC->MC_FSR & (1<<(16+(flashaddr/AT91C_IFLASH_LOCK_REGION_SIZE))) )
        return 1;   // region is locked
    else
        return 0;   // region is not locked
}

void at91flashSetLock(uint32_t flashaddr, int lockstate)
{
    // set the lock state of a flash address/page
    
    // mask flashaddr to size of flash
    flashaddr &= (AT91C_IFLASH_SIZE-1);
    // since lock bits have a small lifetime (100 programming cycles),
    // check to see if lock bit is already set to requested state
    if( at91flashGetLock(flashaddr) == lockstate)
        return;     // lock bit is already set as desired
    // program the lock bit
    if(lockstate)
        AT91C_BASE_MC->MC_FCR = (0x5A<<24) | (((flashaddr/AT91C_IFLASH_PAGE_SIZE)<<8)&AT91C_MC_PAGEN) | AT91C_MC_FCMD_LOCK;
    else
        AT91C_BASE_MC->MC_FCR = (0x5A<<24) | (((flashaddr/AT91C_IFLASH_PAGE_SIZE)<<8)&AT91C_MC_PAGEN) | AT91C_MC_FCMD_UNLOCK;
    // wait for flash done/ready
    while(!(AT91C_BASE_MC->MC_FSR & AT91C_MC_FRDY));
}

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