/*
 * (C) Copyright 2002 ELTEC Elektronik AG
 * Frank Gottschling <fgottschling@eltec.de>
 *
 * See file CREDITS for list of people who contributed to this
 * project.
 *
 * This program 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.
 *
 * This program 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; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 * MA 02111-1307 USA
 */

#include <common.h>
#include "srom.h"

/*----------------------------------------------------------------------------*/
/*
 *  START sequence
 *        _ _________
 *  SCLK  _>         \____
 *        _ ____
 *  SDIO  _>    \_________
 *         :    :    :
 */
static void eepStart (void)
{
    out8(I2C_BUS_DAT, 0x60);     /* SCLK = high  SDIO = high */
    out8(I2C_BUS_DIR, 0x60);     /* set output direction for SCLK/SDIO */
    udelay(10);
    out8(I2C_BUS_DAT, 0x40);     /* SCLK = high  SDIO = low */
    udelay(10);
    out8(I2C_BUS_DAT, 0x00);     /* SCLK = low   SDIO = low */
    udelay(10);
}

/*----------------------------------------------------------------------------*/
/*
 *  STOP sequence
 *              _______
 *  SCLK  _____/
 *        _         ___
 *  SDIO  _>_______/
 *         :   :   :
 */
static void eepStop (void)
{
    out8(I2C_BUS_DAT, 0x00);      /* SCLK = low   SDIO = low */
    out8(I2C_BUS_DIR, 0x60);      /* set output direction for SCLK/SDIO */
    udelay(10);
    out8(I2C_BUS_DAT, 0x40);      /* SCLK = high  SDIO = low */
    udelay(10);
    out8(I2C_BUS_DAT, 0x60);      /* SCLK = high  SDIO = high */
    udelay(10);
    out8(I2C_BUS_DIR, 0x00);      /* reset to input direction */
}

/*----------------------------------------------------------------------------*/
/*
 *  Read one byte from EEPROM
 *            ___     ___     ___     ___     ___     ___     ___     ___
 *  SCLK  ___/   \___/   \___/   \___/   \___/   \___/   \___/   \___/   \
 *        _________________________________________________________________
 *  SDIO  >     ^       ^       ^       ^       ^       ^       ^       ^
 *        :  :   :   :   :   :   :   :   :   :   :   :   :   :   :   :   :
 */
static unsigned char eepReadByte (void)
{
    register unsigned char buf = 0x00;
    register int i;

    out8(I2C_BUS_DIR, 0x40);

    for (i = 0; i < 8; i++)
    {
        out8(I2C_BUS_DAT, 0x00);    /* SCLK = low   SDIO = high */
        udelay(10);
        out8(I2C_BUS_DAT, 0x40);    /* SCLK = high  SDIO = high */
        udelay(15);
        buf <<= 1;
        buf = (in8(I2C_BUS_DAT) & 0x20) ? (buf | 0x01) : (buf & 0xFE);
        out8(I2C_BUS_DAT, 0x00);    /* SCLK = low   SDIO = high */
        udelay(10);
    }
    return(buf);
}

/*----------------------------------------------------------------------------*/
/*
 *  Write one byte to EEPROM
 *           ___     ___     ___     ___     ___     ___     ___     ___
 *  SCLK  __/   \___/   \___/   \___/   \___/   \___/   \___/   \___/   \__
 *         _______ _______ _______ _______ _______ _______ _______ ________
 *  SDIO  X_______X_______X_______X_______X_______X_______X_______X________
 *      :   7   :   6   :   5   :   4   :   3   :   2   :   1   :   0
 */
static void eepWriteByte (register unsigned char buf)
{
    register int    i;

    (buf & 0x80) ? out8(I2C_BUS_DAT, 0x20) : out8(I2C_BUS_DAT, 0x00);     /* SCLK = low   SDIO = data */
    out8(I2C_BUS_DIR, 0x60);

    for (i = 7; i >= 0; i--)
    {
        (buf & 0x80) ? out8(I2C_BUS_DAT, 0x20) : out8(I2C_BUS_DAT, 0x00); /* SCLK=low  SDIO=data */
        udelay(10);
        (buf & 0x80) ? out8(I2C_BUS_DAT, 0x60) : out8(I2C_BUS_DAT, 0x40); /* SCLK=high SDIO=data */
        udelay(15);
        (buf & 0x80) ? out8(I2C_BUS_DAT, 0x20) : out8(I2C_BUS_DAT, 0x00); /* SCLK=low  SDIO=data */
        udelay(10);
        buf <<= 1;
    }
}

/*----------------------------------------------------------------------------*/
/*
 *  Read data acknowledge of EEPROM
 *             _______
 *  SCLK  ____/       \___
 *         _______________
 *  SDIO  >
 *        :   :   ^   :
 */
static int eepReadAck (void)
{
    int retval;

    out8(I2C_BUS_DIR, 0x40);
    out8(I2C_BUS_DAT, 0x00);            /* SCLK = low   SDIO = high */
    udelay(10);
    out8(I2C_BUS_DAT, 0x40);            /* SCLK = high  SDIO = high */
    udelay(10);
    retval = (in8(I2C_BUS_DAT) & 0x20) ? ERROR : 0;
    udelay(10);
    out8(I2C_BUS_DAT, 0x00);            /* SCLK = low   SDIO = high */
    udelay(10);

    return(retval);
}

/*----------------------------------------------------------------------------*/
/*
 *  Write data acknowledge to EEPROM
 *             _______
 *  SCLK  ____/       \___
 *
 *  SDIO  >_______________
 *        :   :       :
 */
static void eepWriteAck (unsigned char ack)
{
    ack ? out8(I2C_BUS_DAT, 0x20) : out8(I2C_BUS_DAT, 0x00); /* SCLK = low   SDIO = ack */
    out8(I2C_BUS_DIR, 0x60);
    udelay(10);
    ack ? out8(I2C_BUS_DAT, 0x60) : out8(I2C_BUS_DAT, 0x40); /* SCLK = high  SDIO = ack */
    udelay(15);
    ack ? out8(I2C_BUS_DAT, 0x20) : out8(I2C_BUS_DAT, 0x00); /* SCLK = low   SDIO = ack */
    udelay(10);
}

/*----------------------------------------------------------------------------*/
/*
 * Read bytes from EEPROM
 */
int el_srom_load (addr, buf, cnt, device, block)
unsigned char addr;
unsigned char *buf;
int cnt;
unsigned char device;
unsigned char block;
{
    register int i;

    for (i=0;i<cnt;i++)
    {
        eepStart();
        eepWriteByte(0xA0 | device | block);
        if (eepReadAck() == ERROR)
        {
           eepStop();
            return(ERROR);
        }
        eepWriteByte(addr++);
        if (eepReadAck() == ERROR)
        {
            eepStop();
            return(ERROR);
        }
        eepStart();

        eepWriteByte(0xA1 | device | block);
        if (eepReadAck() == ERROR)
        {
            eepStop();
            return(ERROR);
        }

        *buf++ = eepReadByte();
        eepWriteAck(1);
        eepStop();

        if ((addr == 0) && (i != (cnt-1)))    /* is it the same block ? */
        {
            if (block == FIRST_BLOCK)
                block = SECOND_BLOCK;
            else
                return(ERROR);
        }
    }
    return(cnt);
}

/*----------------------------------------------------------------------------*/
/*
 *
 * Write bytes to EEPROM
 *
 */
int el_srom_store (addr, buf, cnt, device, block)
unsigned char    addr, *buf, device, block;
int        cnt;
{
    register int i, retVal;

    for (i=0;i<cnt;i++)
    {
        retVal = ERROR;
        do
        {
            eepStart();
            eepWriteByte(0xA0 | device | block);
            if ((retVal = eepReadAck()) == ERROR)
                eepStop();
        } while (retVal == ERROR);

        eepWriteByte(addr++);
        if (eepReadAck() == ERROR)  return(ERROR);

        if ((addr == 0) && (i != (cnt-1)))    /* is it the same block ? */
        {
            if (block == FIRST_BLOCK)
                block = SECOND_BLOCK;
            else
            return(ERROR);
        }

        eepWriteByte(*buf++);
        if (eepReadAck() == ERROR)
            return(ERROR);

        eepStop();
    }
    return(cnt);
}

/*----------------------------------------------------------------------------*/
/*
 * calculate checksum for ELTEC revision srom
 */
unsigned long el_srom_checksum (ptr, size)
register unsigned char *ptr;
unsigned long size;
{
    u_long f, accu = 0;
    u_int  i;
    u_char byte;

    for (; size; size--)
    {
        byte = *ptr++;
        for (i = 8; i; i--)
        {
            f =  ((byte & 1) ^ (accu & 1)) ? 0x84083001 : 0;
            accu >>= 1; accu ^= f;
            byte >>= 1;
        }
    }
    return(accu);
}

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