at91/libat91/eeprom.c

	eeprom.c revision 199767f8919635c4928607450d9e0abb932109ce
/******************************************************************************
 *
 * Filename: eeprom.c
 *
 * Instantiation of eeprom routines
 *
 * Revision information:
 *
 * 28AUG2004    kb_admin    initial creation - adapted from Atmel sources
 * 12JAN2005    kb_admin    fixed clock generation, write polling, init
 *
 * BEGIN_KBDD_BLOCK
 * No warranty, expressed or implied, is included with this software.  It is
 * provided "AS IS" and no warranty of any kind including statutory or aspects
 * relating to merchantability or fitness for any purpose is provided.  All
 * intellectual property rights of others is maintained with the respective
 * owners.  This software is not copyrighted and is intended for reference
 * only.
 * END_BLOCK
 *
 * $FreeBSD$
 *****************************************************************************/

#include "at91rm9200_lowlevel.h"
#include "at91rm9200.h"
#include "lib.h"

/******************************* GLOBALS *************************************/


/*********************** PRIVATE FUNCTIONS/DATA ******************************/


/* Use a macro to calculate the TWI clock generator value to save code space. */
#define AT91C_TWSI_CLOCK    100000
#define TWSI_EEPROM_ADDRESS 0x50

#define TWI_CLK_BASE_DIV    ((AT91C_MASTER_CLOCK/(4*AT91C_TWSI_CLOCK)) - 2)
#define SET_TWI_CLOCK   ((0x00010000) | (TWI_CLK_BASE_DIV) | (TWI_CLK_BASE_DIV << 8))


/*************************** GLOBAL FUNCTIONS ********************************/


/*
 * .KB_C_FN_DEFINITION_START
 * void InitEEPROM(void)
 *  This global function initializes the EEPROM interface (TWI).  Intended
 * to be called a single time.
 * .KB_C_FN_DEFINITION_END
 */
void
InitEEPROM(void)
{

    AT91PS_TWI twiPtr = (AT91PS_TWI)AT91C_BASE_TWI;

    AT91PS_PIO pPio = (AT91PS_PIO)AT91C_BASE_PIOA;
    AT91PS_PMC pPMC = (AT91PS_PMC)AT91C_BASE_PMC;

    pPio->PIO_ASR = AT91C_PIO_PA25 | AT91C_PIO_PA26;
    pPio->PIO_PDR = AT91C_PIO_PA25 | AT91C_PIO_PA26;

    pPio->PIO_MDDR = ~AT91C_PIO_PA25;
    pPio->PIO_MDER = AT91C_PIO_PA25;

    pPMC->PMC_PCER = 1u << AT91C_ID_TWI;

    twiPtr->TWI_IDR = 0xffffffffu;
    twiPtr->TWI_CR = AT91C_TWI_SWRST;
    twiPtr->TWI_CR = AT91C_TWI_MSEN | AT91C_TWI_SVDIS;

    twiPtr->TWI_CWGR = SET_TWI_CLOCK;
}


/*
 * .KB_C_FN_DEFINITION_START
 * void ReadEEPROM(unsigned ee_addr, char *data_addr, unsigned size)
 *  This global function reads data from the eeprom at ee_addr storing data
 * to data_addr for size bytes.  Assume the TWI has been initialized.
 * This function does not utilize the page read mode to simplify the code.
 * .KB_C_FN_DEFINITION_END
 */
int
ReadEEPROM(unsigned ee_off, unsigned char *data_addr, unsigned size)
{
    const AT91PS_TWI    twiPtr = AT91C_BASE_TWI;
    unsigned int status;
    unsigned int count;

    status = twiPtr->TWI_SR;
    status = twiPtr->TWI_RHR;

    // Set the TWI Master Mode Register
    twiPtr->TWI_MMR = (TWSI_EEPROM_ADDRESS << 16) |
        AT91C_TWI_IADRSZ_2_BYTE | AT91C_TWI_MREAD;

    // Set TWI Internal Address Register
    twiPtr->TWI_IADR = ee_off;

    // Start transfer
    twiPtr->TWI_CR = AT91C_TWI_START;

    status = twiPtr->TWI_SR;

    while (size-- > 1){
        // Wait RHR Holding register is full
        count = 1000000;
        while (!(twiPtr->TWI_SR & AT91C_TWI_RXRDY) && --count > 0)
            continue;
        if (count <= 0)
            return -1;

        // Read byte
        *(data_addr++) = twiPtr->TWI_RHR;
    }

    twiPtr->TWI_CR = AT91C_TWI_STOP;

    status = twiPtr->TWI_SR;

    // Wait transfer is finished
    while (!(twiPtr->TWI_SR & AT91C_TWI_TXCOMP))
        continue;

    // Read last byte
    *data_addr = twiPtr->TWI_RHR;
    return 0;
}


/*
 * .KB_C_FN_DEFINITION_START
 * void WriteEEPROM(unsigned ee_off, char *data_addr, unsigned size)
 *  This global function writes data to the eeprom at ee_off using data
 * from data_addr for size bytes.  Assume the TWI has been initialized.
 * This function does not utilize the page write mode as the write time is
 * much greater than the time required to access the device for byte-write
 * functionality.  This allows the function to be much simpler.
 * .KB_C_FN_DEFINITION_END
 */
void
WriteEEPROM(unsigned ee_off, char *data_addr, unsigned size)
{
    const AT91PS_TWI    twiPtr = AT91C_BASE_TWI;
    unsigned        status;
    unsigned char       test_data;

    while (size--) {
        if (!(ee_off & 0x3f))
            putchar('.');

        // Set the TWI Master Mode Register
        twiPtr->TWI_MMR = ((TWSI_EEPROM_ADDRESS << 16) |
            AT91C_TWI_IADRSZ_2_BYTE) & ~AT91C_TWI_MREAD;

        // Set TWI Internal Address Register
        twiPtr->TWI_IADR = ee_off++;

        status = twiPtr->TWI_SR;

        twiPtr->TWI_THR = *(data_addr++);

        twiPtr->TWI_CR = AT91C_TWI_START;

        // Wait transfer is finished
        while (!(twiPtr->TWI_SR & AT91C_TWI_TXRDY))
            continue;

        twiPtr->TWI_CR = AT91C_TWI_STOP;

        status = twiPtr->TWI_SR;

        // Wait transfer is finished
        while (!(twiPtr->TWI_SR & AT91C_TWI_TXCOMP))
            continue;

        // wait for write operation to complete
        ReadEEPROM(ee_off, &test_data, 1);
    }

    putchar('\r');
    putchar('\n');
}