i2c_bitbang.c

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#include "hw/hw_i2c_bitbang.h"

#include "cfg/cfg_i2c.h"

#define LOG_LEVEL  I2C_LOG_LEVEL
#define LOG_FORMAT I2C_LOG_FORMAT

#include <cfg/log.h>
#include <cfg/macros.h>
#include <cfg/module.h>

#include <drv/timer.h>
#include <drv/i2c.h>

#include <cpu/irq.h>

#include <cpu/attr.h>

#if !CONFIG_I2C_DISABLE_OLD_API

INLINE bool i2c_bitbang_start(void)
{
    SDA_HI;
    SCL_HI;
    I2C_HALFBIT_DELAY();
    SDA_LO;
    I2C_HALFBIT_DELAY();

    return !SDA_IN;
}

void i2c_bitbang_stop(void)
{
    SDA_LO;
    SCL_HI;
    I2C_HALFBIT_DELAY();
    SDA_HI;
}

bool i2c_bitbang_put(uint8_t _data)
{
    /* Add ACK bit */
    uint16_t data = (_data << 1) | 1;

    for (uint16_t i = 0x100; i != 0; i >>= 1)
    {
        SCL_LO;
        if (data & i)
            SDA_HI;
        else
            SDA_LO;
        I2C_HALFBIT_DELAY();

        SCL_HI;
        I2C_HALFBIT_DELAY();
    }

    bool ack = !SDA_IN;
    SCL_LO;
    I2C_HALFBIT_DELAY();
    return ack;
}

bool i2c_bitbang_start_w(uint8_t id)
{
    id &= ~I2C_READBIT;
    /*
     * Loop on the select write sequence: when the device is busy
     * writing previously sent data it will reply to the SLA_W
     * control byte with a NACK.  In this case, we must
     * keep trying until the deveice responds with an ACK.
     */
    ticks_t start = timer_clock();
    while (i2c_bitbang_start())
    {
        if (i2c_bitbang_put(id))
            return true;
        else if (timer_clock() - start > ms_to_ticks(CONFIG_I2C_START_TIMEOUT))
        {
            LOG_ERR("Timeout on I2C start write\n");
            break;
        }
        //LOG_INFO("Rep start\n");
    }

    return false;
}

bool i2c_bitbang_start_r(uint8_t id)
{
    id |= I2C_READBIT;
    if (i2c_bitbang_start())
    {
        if (i2c_bitbang_put(id))
            return true;

        LOG_ERR("NACK on I2c start read\n");
    }

    return false;
}

int i2c_bitbang_get(bool ack)
{
    uint8_t data = 0;
    for (uint8_t i = 0x80; i != 0; i >>= 1)
    {
        SCL_LO;
        I2C_HALFBIT_DELAY();
        SCL_HI;
        if (SDA_IN)
            data |= i;
        else
            data &= ~i;

        I2C_HALFBIT_DELAY();
    }
    SCL_LO;

    if (ack)
        SDA_LO;
    else
        SDA_HI;

    I2C_HALFBIT_DELAY();
    SCL_HI;
    I2C_HALFBIT_DELAY();
    SCL_LO;
    SDA_HI;
    /* avoid sign extension */
    return (int)(uint8_t)data;
}

#endif /* !CONFIG_I2C_DISABLE_OLD_API */

/*
 * New I2C API
 */
static bool old_api = false;
#define I2C_DEV(i2c)            ((int)((i2c)->hw))

static void i2c_bitbang_stop_1(struct I2c *i2c)
{
    if (old_api)
    {
        SDA_LO;
        SCL_HI;
        I2C_HALFBIT_DELAY();
        SDA_HI;
    }
    else
    {
        i2c_sdaLo(I2C_DEV(i2c));
        i2c_sclHi(I2C_DEV(i2c));
        i2c_halfbitDelay(I2C_DEV(i2c));
        i2c_sdaHi(I2C_DEV(i2c));
    }
}

INLINE bool i2c_bitbang_start_1(struct I2c *i2c)
{
    bool ret;
    /* Clear all error, we restart */
    i2c->errors &= ~(I2C_NO_ACK | I2C_ARB_LOST);

    if (old_api)
    {
        SDA_HI;
        SCL_HI;
        I2C_HALFBIT_DELAY();
        SDA_LO;
        I2C_HALFBIT_DELAY();

        ret = !SDA_IN;
    }
    else
    {
        i2c_sdaHi(I2C_DEV(i2c));
        i2c_sclHi(I2C_DEV(i2c));
        i2c_halfbitDelay(I2C_DEV(i2c));
        i2c_sdaLo(I2C_DEV(i2c));
        i2c_halfbitDelay(I2C_DEV(i2c));

        ret = !i2c_sdaIn(I2C_DEV(i2c));
    }

    return ret;
}


static uint8_t i2c_bitbang_getc(struct I2c *i2c)
{
    uint8_t data = 0;
    if (old_api)
    {
        for (uint8_t i = 0x80; i != 0; i >>= 1)
        {
            SCL_LO;
            I2C_HALFBIT_DELAY();
            SCL_HI;
            if (SDA_IN)
                data |= i;
            else
                data &= ~i;

            I2C_HALFBIT_DELAY();
        }
        SCL_LO;

        /* Generate ACK/NACK */
        if (i2c->xfer_size > 1)
            SDA_LO;
        else
            SDA_HI;

        I2C_HALFBIT_DELAY();
        SCL_HI;
        I2C_HALFBIT_DELAY();
        SCL_LO;
        SDA_HI;
    }
    else
    {
        for (uint8_t i = 0x80; i != 0; i >>= 1)
        {
            i2c_sclLo(I2C_DEV(i2c));
            i2c_halfbitDelay(I2C_DEV(i2c));
            i2c_sclHi(I2C_DEV(i2c));
            if (i2c_sdaIn(I2C_DEV(i2c)))
                data |= i;
            else
                data &= ~i;

            i2c_halfbitDelay(I2C_DEV(i2c));
        }
        i2c_sclLo(I2C_DEV(i2c));

        /* Generate ACK/NACK */
        if (i2c->xfer_size > 1)
            i2c_sdaLo(I2C_DEV(i2c));
        else
            i2c_sdaHi(I2C_DEV(i2c));

        i2c_halfbitDelay(I2C_DEV(i2c));
        i2c_sclHi(I2C_DEV(i2c));
        i2c_halfbitDelay(I2C_DEV(i2c));
        i2c_sclLo(I2C_DEV(i2c));
        i2c_sdaHi(I2C_DEV(i2c));
    }

    /* Generate stop condition (if requested) */
    if ((i2c->xfer_size == 1) && (i2c->flags & I2C_STOP))
        i2c_bitbang_stop_1(i2c);

    return data;
}

INLINE void i2c_bitbang_putcStop(struct I2c *i2c, uint8_t _data, bool stop)
{
    /* Add ACK bit */
    uint16_t data = (_data << 1) | 1;
    bool ack;

    if (old_api)
    {
        for (uint16_t i = 0x100; i != 0; i >>= 1)
        {
            SCL_LO;
            if (data & i)
                SDA_HI;
            else
                SDA_LO;
            I2C_HALFBIT_DELAY();

            SCL_HI;
            I2C_HALFBIT_DELAY();
        }

        ack = !SDA_IN;
        SCL_LO;
        I2C_HALFBIT_DELAY();
    }
    else
    {
        for (uint16_t i = 0x100; i != 0; i >>= 1)
        {
            i2c_sclLo(I2C_DEV(i2c));
            if (data & i)
                i2c_sdaHi(I2C_DEV(i2c));
            else
                i2c_sdaLo(I2C_DEV(i2c));
            i2c_halfbitDelay(I2C_DEV(i2c));

            i2c_sclHi(I2C_DEV(i2c));
            i2c_halfbitDelay(I2C_DEV(i2c));
        }
        ack = !i2c_sdaIn(I2C_DEV(i2c));

        i2c_sclLo(I2C_DEV(i2c));
        i2c_halfbitDelay(I2C_DEV(i2c));
    }

    if (!ack)
        i2c->errors |= I2C_NO_ACK;

    /* Generate stop condition (if requested) */
    if (stop || i2c->errors)
        i2c_bitbang_stop_1(i2c);
}

static void i2c_bitbang_putc(struct I2c *i2c, uint8_t data)
{
    i2c_bitbang_putcStop(i2c, data,
        (i2c->xfer_size == 1) && (i2c->flags & I2C_STOP));
}

static void i2c_bitbang_start_2(struct I2c *i2c, uint16_t slave_addr)
{
    if (i2c->flags & I2C_START_R)
        slave_addr |= I2C_READBIT;
    else
        slave_addr &= ~I2C_READBIT;

    /*
     * Loop on the select write sequence: when the device is busy
     * writing previously sent data it will reply to the SLA_W
     * control byte with a NACK.  In this case, we must
     * keep trying until the device responds with an ACK.
     */
    ticks_t start = timer_clock();
    while (i2c_bitbang_start_1(i2c))
    {
        i2c_bitbang_putcStop(i2c, slave_addr, false);

        if (!(i2c->errors & I2C_NO_ACK))
            return;
        else if (timer_clock() - start > ms_to_ticks(CONFIG_I2C_START_TIMEOUT))
        {
            LOG_ERR("Timeout on I2C start\n");
            i2c->errors |= I2C_START_TIMEOUT;
            i2c_bitbang_stop_1(i2c);
            return;
        }
    }

    LOG_ERR("START arbitration lost\n");
    i2c->errors |= I2C_ARB_LOST;
    i2c_bitbang_stop_1(i2c);
    return;
}


static const I2cVT i2c_bitbang_vt =
{
    .start = i2c_bitbang_start_2,
    .getc = i2c_bitbang_getc,
    .putc = i2c_bitbang_putc,
    .write = i2c_genericWrite,
    .read = i2c_genericRead,
};


void i2c_hw_bitbangInit(I2c *i2c, int dev)
{
    MOD_CHECK(timer);
    if (dev == I2C_BITBANG_OLD)
        old_api = true;
    else
        i2c->hw = (struct I2cHardware *)(dev - I2C_BITBANG0);

    i2c->vt = &i2c_bitbang_vt;

    if (old_api)
    {
        I2C_BITBANG_HW_INIT;
        SDA_HI;
        SCL_HI;
    }
    else
    {
        i2c_bitbangInit(I2C_DEV(i2c));
        i2c_sdaHi(I2C_DEV(i2c));
        i2c_sclHi(I2C_DEV(i2c));
    }
}