/* ------------------------------------------------------------------------- */
/* i2c-algo-bit.c i2c driver algorithms for bit-shift adapters		     */
/* ------------------------------------------------------------------------- */
/*   Copyright (C) 1995-2000 Simon G. Vogl

    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., 675 Mass Ave, Cambridge, MA 02139, USA.		     */
/* ------------------------------------------------------------------------- */

/* With some changes from Frodo Looijaard <frodol@dds.nl>, Kyösti Mälkki
   <kmalkki@cc.hut.fi> and Jean Delvare <khali@linux-fr.org> */

#include "wait.h"
#include "i2c.h"
#include "i2c-algo-bit.h"

#ifndef NULL
#define NULL ((void *)0)
#endif

// #define DEBUG
#include "debug.h"

extern void start_timeout(void);
extern int end_timeout(long msec);

/* --- setting states on the bus with the right timing: ---------------	*/

#define setsda(adap,val) adap->setsda(adap->data, val)
#define setscl(adap,val) adap->setscl(adap->data, val)
#define getsda(adap) adap->getsda(adap->data)
#define getscl(adap) adap->getscl(adap->data)

static inline void sdalo(struct i2c_algo_bit_data *adap)
{
    setsda(adap,0);
    wait_us(adap->udelay);
}

static inline void sdahi(struct i2c_algo_bit_data *adap)
{
    setsda(adap,1);
    wait_us(adap->udelay);
}

static inline void scllo(struct i2c_algo_bit_data *adap)
{
    setscl(adap,0);
    wait_us(adap->udelay);
}

/*
 * Raise scl line, and do checking for delays. This is necessary for slower
 * devices.
 */
static inline int sclhi(struct i2c_algo_bit_data *adap)
{
    setscl(adap, 1);
    /* Not all adapters have scl sense line... */
    if(adap->getscl == NULL )
    {
        wait_us(adap->udelay);
        return 0;
    }
    start_timeout();
    while (! getscl(adap))
    {
        /* the hw knows how to read the clock line,
         * so we wait until it actually gets high.
         * This is safer as some chips may hold it low
         * while they are processing data internally.
         */
        if (end_timeout((long)adap->timeout))
            return -110;
    }
    wait_us(adap->udelay);
    return 0;
}


/* --- other auxiliary functions --------------------------------------	*/
void i2c_start(struct i2c_algo_bit_data *adap)
{
    /* assert: scl, sda are high */
    sdalo(adap);
    scllo(adap);
}

static void i2c_repstart(struct i2c_algo_bit_data *adap)
{
    /* scl, sda may not be high */
    setsda(adap, 1);
    sclhi(adap);
    wait_us(adap->udelay);
    sdalo(adap);
    scllo(adap);
}

static void i2c_stop(struct i2c_algo_bit_data *adap)
{
    /* assert: scl is low */
    sdalo(adap);
    sclhi(adap);
    sdahi(adap);
}

/*
 * send a byte without start cond., look for arbitration,
 * check ackn. from slave
 *
 * returns:
 * 1 if the device acknowledged
 * 0 if the device did not ack
 * -ETIMEDOUT if an error occurred (while raising the scl line)
 */
static int i2c_outb(struct i2c_adapter *i2c_adap, char c)
{
    int i;
    int sb;
    int ack;
    struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
    /* assert: scl is low */

    for (i = 7; i >= 0; i--)
    {
        sb = c & (1 << i);
        setsda(adap,sb);
        wait_us(adap->udelay);
        if (sclhi(adap) < 0)
        {
            /* timed out */
            sdahi(adap); /* we don't want to block the net */
#ifdef DEBUG
            dbg("ETIMEDOUT\r\n");
#endif
            return -110;
        };
        /* do arbitration here:
         * if ( sb && ! getsda(adap) ) -> ouch! Get out of here.
         */
        setscl(adap, 0 );
        wait_us(adap->udelay);
    }
    sdahi(adap);
    if(sclhi(adap)<0)
    {
        /* timeout */

        dbg("ETIMEDOUT\r\n");

        return -110;
    }
    /* read ack: SDA should be pulled down by slave */
    ack = getsda(adap);	/* ack: sda is pulled low ->success.	 */
    scllo(adap);

    dbg("0x%02x, ack=0x%02x\r\n", (unsigned long)(c & 0xff), ack);

    return 0 == ack;		/* return 1 if device acked	 */
    /* assert: scl is low (sda undef) */
}

static int i2c_inb(struct i2c_adapter *i2c_adap)
{
    /* read byte via i2c port, without start/stop sequence	*/
    /* acknowledge is sent in i2c_read.			*/
    int i;
    unsigned char indata = 0;
    struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
    /* assert: scl is low */
    sdahi(adap);
    for(i = 0; i < 8; i++)
    {
        if (sclhi(adap) < 0)
        {
            /* timeout */
            dbg("i2c_inb TIMEDOUT\r\n");
            return -110;
        }
        indata *= 2;
        if (getsda(adap))
            indata |= 0x01;
        scllo(adap);
    }
    /* assert: scl is low */
    dbg("0x%02x\r\n", (unsigned long)(indata & 0xff));

    return (int) (indata & 0xff);
}

/*
 * Sanity check for the adapter hardware - check the reaction of
 * the bus lines only if it seems to be idle.
 */
static int test_bus(struct i2c_algo_bit_data *adap)
{
    int scl, sda;
    sda = getsda(adap);
    scl = (adap->getscl == NULL ? 1 : getscl(adap));
    if (!scl || !sda )
        goto bailout;
    sdalo(adap);
    sda = getsda(adap);
    scl = (adap->getscl == NULL ? 1 : getscl(adap));
    if (sda !=0 || scl == 0)
        goto bailout;
    sdahi(adap);
    sda = getsda(adap);
    scl = (adap->getscl == NULL ? 1 : getscl(adap));
    if (sda == 0 || scl ==0)
        goto bailout;
    scllo(adap);
    sda = getsda(adap);
    scl = (adap->getscl == NULL ? 0 : getscl(adap));
    if (scl !=0 || sda == 0)
        goto bailout;
    sclhi(adap);
    sda = getsda(adap);
    scl = (adap->getscl == NULL ? 1 : getscl(adap));
    if (scl == 0 || sda ==0)
        goto bailout;
    return 0;
bailout:
    sdahi(adap);
    sclhi(adap);
    return -110;
}

/* ----- Utility functions
 */

/* try_address tries to contact a chip for a number of
 * times before it gives up.
 * return values:
 * 1 chip answered
 * 0 chip did not answer
 * -x transmission error
 */
static inline int try_address(struct i2c_adapter *i2c_adap,
                              unsigned char addr, int retries)
{
    struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
    int i, ret = -1;
    for (i = 0; i <= retries; i++)
    {
        ret = i2c_outb(i2c_adap, addr);
        if (ret == 1)
            break;	/* success! */
        i2c_stop(adap);
        wait_us(5);
        if (i == retries)  /* no success */
            break;
        i2c_start(adap);
        wait_us(adap->udelay);
    }
    return ret;
}

static int sendbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
{
    struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
    char c;
    const char *temp = (const char *)msg->buf;
    int count = msg->len;
    unsigned short nak_ok = msg->flags & I2C_M_IGNORE_NAK;
    int retval;
    int wrcount=0;
    while(count > 0)
    {
        c = *temp;
        retval = i2c_outb(i2c_adap,c);
        if ((retval > 0) || (nak_ok && (retval==0)))
        { /* ok or ignored NAK */
            count--;
            temp++;
            wrcount++;
        }
        else
        { /* arbitration or no acknowledge */
            i2c_stop(adap);
            return (retval < 0)? retval : -110;
            /* got a better one ?? */
        }
    }
    return wrcount;
}

static inline int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
{
    int inval;
    int rdcount=0;   	/* counts bytes read */
    struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
    char *temp = (char *)msg->buf;
    int count = msg->len;
    while(count > 0)
    {
        inval = i2c_inb(i2c_adap);
        if (inval >= 0)
        {
            *temp = inval;
            rdcount++;
        }
        else
            /* read timed out */
            break;
        temp++;
        count--;
        if (msg->flags & I2C_M_NO_RD_ACK)
            continue;
        if (count > 0)
            /* send ack */
            sdalo(adap);
        else
            sdahi(adap);	/* neg. ack on last byte */
        if (sclhi(adap) < 0)
        {
            /* timeout */
            sdahi(adap);
            return -1;
        };
        scllo(adap);
        sdahi(adap);
    }
    return rdcount;
}

/* doAddress initiates the transfer by generating the start condition (in
 * try_address) and transmits the address in the necessary format to handle
 * reads, writes as well as 10bit-addresses.
 * returns:
 *  0 everything went okay, the chip ack'ed, or IGNORE_NAK flag was set
 * -x an error occurred (like: -EREMOTEIO if the device did not answer, or
 *	-ETIMEDOUT, for example if the lines are stuck...)
 */
static inline int bit_doAddress(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
{
    unsigned short flags = msg->flags;
    unsigned short nak_ok = msg->flags & I2C_M_IGNORE_NAK;
    struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
    unsigned char addr;
    int ret, retries;
    retries = nak_ok ? 0 : i2c_adap->retries;
    if (flags & I2C_M_TEN)
    {
        /* a ten bit address */
        addr = 0xf0 | (( msg->addr >> 7) & 0x03);
        /* try extended address code...*/
        ret = try_address(i2c_adap, addr, retries);
        if ((ret != 1) && !nak_ok)
            return -1;
        /* the remaining 8 bit address */
        ret = i2c_outb(i2c_adap,msg->addr & 0x7f);
        if ((ret != 1) && !nak_ok)
            /* the chip did not ack / xmission error occurred */
            return -1;
        if (flags & I2C_M_RD)
        {
            i2c_repstart(adap);
            /* okay, now switch into reading mode */
            addr |= 0x01;
            ret = try_address(i2c_adap, addr, retries);
            if ((ret != 1) && !nak_ok)
                return -1;
        }
    }
    else
    {		/* normal 7bit address	*/
        addr = (msg->addr << 1);
        if (flags & I2C_M_RD )
            addr |= 1;
        if (flags & I2C_M_REV_DIR_ADDR )
            addr ^= 1;
        ret = try_address(i2c_adap, addr, retries);
        if ((ret != 1) && !nak_ok)
            return -1;
    }
    return 0;
}

static int bit_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg msgs[], int num)
{
    struct i2c_msg *pmsg;
    struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
    int i,ret;
    unsigned short nak_ok;
    i2c_start(adap);
    for(i=0;i<num;i++)
    {
        pmsg = &msgs[i];
        nak_ok = pmsg->flags & I2C_M_IGNORE_NAK;
        if(!(pmsg->flags & I2C_M_NOSTART))
        {
            if (i)
                i2c_repstart(adap);
            ret = bit_doAddress(i2c_adap, pmsg);
            if ((ret != 0) && !nak_ok)
                return (ret < 0) ? ret : -1;
        }
        if(pmsg->flags & I2C_M_RD )
        {
            /* read bytes into buffer*/
            ret = readbytes(i2c_adap, pmsg);
            if(ret < pmsg->len)
                return (ret < 0)? ret : -1;
        }
        else
        {
            /* write bytes from buffer */
            ret = sendbytes(i2c_adap, pmsg);
            if (ret < pmsg->len )
                return (ret < 0) ? ret : -1;
        }
    }
    i2c_stop(adap);
    return num;
}

/* -----exported algorithm data: -------------------------------------	*/

static struct i2c_algorithm i2c_bit_algo = {
    .master_xfer = bit_xfer,
};

/*
 * registering functions to load algorithms at runtime
 */
int i2c_bit_add_bus(struct i2c_adapter *adap)
{
    struct i2c_algo_bit_data *bit_adap = adap->algo_data;
    if (1)
    {
        int ret = test_bus(bit_adap);
        if (ret < 0)
            return -1;
    }
    /* register new adapter to i2c module... */
    adap->algo = &i2c_bit_algo;
    adap->timeout = 10;         /* default values, should	*/
    adap->retries = 3;          /* be replaced by defines	*/
    return 0;
}

int i2c_bit_del_bus(struct i2c_adapter *adap)
{
    return 0;
}

/* ----------------------------------------------------
 * the functional interface to the i2c busses.
 * ----------------------------------------------------
 */

int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
{
    int ret;
    if (adap->algo->master_xfer)
    {
        ret = adap->algo->master_xfer(adap, msgs, num);
        return ret;
    }
    else
        return -1;
}
