ftdi.c

libftdi - A library (using libusb) to talk to FTDI s FT2232C, FT232BM and FT245BM type chips includ

        ftdi_error_return(-2, "FTDI purge of TX buffer failed");

    return 0;
}

/**
    Closes the ftdi device. Call ftdi_deinit() if you're cleaning up.

    \param ftdi pointer to ftdi_context

    \retval  0: all fine
    \retval -1: usb_release failed
    \retval -2: usb_close failed
*/
int ftdi_usb_close(struct ftdi_context *ftdi)
{
    int rtn = 0;

    if (usb_release_interface(ftdi->usb_dev, ftdi->interface) != 0)
        rtn = -1;

    if (usb_close (ftdi->usb_dev) != 0)
        rtn = -2;

    return rtn;
}

/*
    ftdi_convert_baudrate returns nearest supported baud rate to that requested.
    Function is only used internally
    \internal
*/
static int ftdi_convert_baudrate(int baudrate, struct ftdi_context *ftdi,
                                 unsigned short *value, unsigned short *index)
{
    static const char am_adjust_up[8] = {0, 0, 0, 1, 0, 3, 2, 1};
    static const char am_adjust_dn[8] = {0, 0, 0, 1, 0, 1, 2, 3};
    static const char frac_code[8] = {0, 3, 2, 4, 1, 5, 6, 7};
    int divisor, best_divisor, best_baud, best_baud_diff;
    unsigned long encoded_divisor;
    int i;

    if (baudrate <= 0) {
        // Return error
        return -1;
    }

    divisor = 24000000 / baudrate;

    if (ftdi->type == TYPE_AM) {
        // Round down to supported fraction (AM only)
        divisor -= am_adjust_dn[divisor & 7];
    }

    // Try this divisor and the one above it (because division rounds down)
    best_divisor = 0;
    best_baud = 0;
    best_baud_diff = 0;
    for (i = 0; i < 2; i++) {
        int try_divisor = divisor + i;
        int baud_estimate;
        int baud_diff;

        // Round up to supported divisor value
        if (try_divisor <= 8) {
            // Round up to minimum supported divisor
            try_divisor = 8;
        } else if (ftdi->type != TYPE_AM && try_divisor < 12) {
            // BM doesn't support divisors 9 through 11 inclusive
            try_divisor = 12;
        } else if (divisor < 16) {
            // AM doesn't support divisors 9 through 15 inclusive
            try_divisor = 16;
        } else {
            if (ftdi->type == TYPE_AM) {
                // Round up to supported fraction (AM only)
                try_divisor += am_adjust_up[try_divisor & 7];
                if (try_divisor > 0x1FFF8) {
                    // Round down to maximum supported divisor value (for AM)
                    try_divisor = 0x1FFF8;
                }
            } else {
                if (try_divisor > 0x1FFFF) {
                    // Round down to maximum supported divisor value (for BM)
                    try_divisor = 0x1FFFF;
                }
            }
        }
        // Get estimated baud rate (to nearest integer)
        baud_estimate = (24000000 + (try_divisor / 2)) / try_divisor;
        // Get absolute difference from requested baud rate
        if (baud_estimate < baudrate) {
            baud_diff = baudrate - baud_estimate;
        } else {
            baud_diff = baud_estimate - baudrate;
        }
        if (i == 0 || baud_diff < best_baud_diff) {
            // Closest to requested baud rate so far
            best_divisor = try_divisor;
            best_baud = baud_estimate;
            best_baud_diff = baud_diff;
            if (baud_diff == 0) {
                // Spot on! No point trying
                break;
            }
        }
    }
    // Encode the best divisor value
    encoded_divisor = (best_divisor >> 3) | (frac_code[best_divisor & 7] << 14);
    // Deal with special cases for encoded value
    if (encoded_divisor == 1) {
        encoded_divisor = 0;    // 3000000 baud
    } else if (encoded_divisor == 0x4001) {
        encoded_divisor = 1;    // 2000000 baud (BM only)
    }
    // Split into "value" and "index" values
    *value = (unsigned short)(encoded_divisor & 0xFFFF);
    if(ftdi->type == TYPE_2232C) {
        *index = (unsigned short)(encoded_divisor >> 8);
        *index &= 0xFF00;
        *index |= ftdi->index;
    }
    else
        *index = (unsigned short)(encoded_divisor >> 16);

    // Return the nearest baud rate
    return best_baud;
}

/**
    Sets the chip baud rate

    \param ftdi pointer to ftdi_context
    \param baudrate baud rate to set

    \retval  0: all fine
    \retval -1: invalid baudrate
    \retval -2: setting baudrate failed
*/
int ftdi_set_baudrate(struct ftdi_context *ftdi, int baudrate)
{
    unsigned short value, index;
    int actual_baudrate;

    if (ftdi->bitbang_enabled) {
        baudrate = baudrate*4;
    }

    actual_baudrate = ftdi_convert_baudrate(baudrate, ftdi, &value, &index);
    if (actual_baudrate <= 0)
        ftdi_error_return (-1, "Silly baudrate <= 0.");

    // Check within tolerance (about 5%)
    if ((actual_baudrate * 2 < baudrate /* Catch overflows */ )
            || ((actual_baudrate < baudrate)
                ? (actual_baudrate * 21 < baudrate * 20)
                : (baudrate * 21 < actual_baudrate * 20)))
        ftdi_error_return (-1, "Unsupported baudrate. Note: bitbang baudrates are automatically multiplied by 4");

    if (usb_control_msg(ftdi->usb_dev, 0x40, 3, value, index, NULL, 0, ftdi->usb_write_timeout) != 0)
        ftdi_error_return (-2, "Setting new baudrate failed");

    ftdi->baudrate = baudrate;
    return 0;
}

/**
    Set (RS232) line characteristics by Alain Abbas

    \param ftdi pointer to ftdi_context
    \param bits Number of bits
    \param sbit Number of stop bits
    \param parity Parity mode

    \retval  0: all fine
    \retval -1: Setting line property failed
*/
int ftdi_set_line_property(struct ftdi_context *ftdi, enum ftdi_bits_type bits,
                           enum ftdi_stopbits_type sbit, enum ftdi_parity_type parity)
{
    unsigned short value = bits;

    switch(parity) {
    case NONE:
        value |= (0x00 << 8);
        break;
    case ODD:
        value |= (0x01 << 8);
        break;
    case EVEN:
        value |= (0x02 << 8);
        break;
    case MARK:
        value |= (0x03 << 8);
        break;
    case SPACE:
        value |= (0x04 << 8);
        break;
    }

    switch(sbit) {
    case STOP_BIT_1:
        value |= (0x00 << 11);
        break;
    case STOP_BIT_15:
        value |= (0x01 << 11);
        break;
    case STOP_BIT_2:
        value |= (0x02 << 11);
        break;
    }

    if (usb_control_msg(ftdi->usb_dev, 0x40, 0x04, value, ftdi->index, NULL, 0, ftdi->usb_write_timeout) != 0)
        ftdi_error_return (-1, "Setting new line property failed");

    return 0;
}

/**
    Writes data in chunks (see ftdi_write_data_set_chunksize()) to the chip

    \param ftdi pointer to ftdi_context
    \param buf Buffer with the data
    \param size Size of the buffer

    \retval <0: error code from usb_bulk_write()
    \retval >0: number of bytes written
*/
int ftdi_write_data(struct ftdi_context *ftdi, unsigned char *buf, int size)
{
    int ret;
    int offset = 0;
    int total_written = 0;

    while (offset < size) {
        int write_size = ftdi->writebuffer_chunksize;

        if (offset+write_size > size)
            write_size = size-offset;

        ret = usb_bulk_write(ftdi->usb_dev, ftdi->in_ep, buf+offset, write_size, ftdi->usb_write_timeout);
        if (ret < 0)
            ftdi_error_return(ret, "usb bulk write failed");

        total_written += ret;
        offset += write_size;
    }

    return total_written;
}

/**
    Configure write buffer chunk size.
    Default is 4096.

    \param ftdi pointer to ftdi_context
    \param chunksize Chunk size

    \retval 0: all fine
*/
int ftdi_write_data_set_chunksize(struct ftdi_context *ftdi, unsigned int chunksize)
{
    ftdi->writebuffer_chunksize = chunksize;
    return 0;
}

/**
    Get write buffer chunk size.

    \param ftdi pointer to ftdi_context
    \param chunksize Pointer to store chunk size in

    \retval 0: all fine
*/
int ftdi_write_data_get_chunksize(struct ftdi_context *ftdi, unsigned int *chunksize)
{
    *chunksize = ftdi->writebuffer_chunksize;
    return 0;
}

/**
    Reads data in chunks (see ftdi_read_data_set_chunksize()) from the chip.

    Automatically strips the two modem status bytes transfered during every read.

    \param ftdi pointer to ftdi_context
    \param buf Buffer to store data in
    \param size Size of the buffer

    \retval <0: error code from usb_bulk_read()
    \retval  0: no data was available
    \retval >0: number of bytes read

    \remark This function is not useful in bitbang mode.
            Use ftdi_read_pins() to get the current state of the pins.
*/
int ftdi_read_data(struct ftdi_context *ftdi, unsigned char *buf, int size)
{
    int offset = 0, ret = 1, i, num_of_chunks, chunk_remains;

    // everything we want is still in the readbuffer?
    if (size <= ftdi->readbuffer_remaining) {
        memcpy (buf, ftdi->readbuffer+ftdi->readbuffer_offset, size);

        // Fix offsets
        ftdi->readbuffer_remaining -= size;
        ftdi->readbuffer_offset += size;

        /* printf("Returning bytes from buffer: %d - remaining: %d\n", size, ftdi->readbuffer_remaining); */

        return size;
    }
    // something still in the readbuffer, but not enough to satisfy 'size'?
    if (ftdi->readbuffer_remaining != 0) {
        memcpy (buf, ftdi->readbuffer+ftdi->readbuffer_offset, ftdi->readbuffer_remaining);

        // Fix offset
        offset += ftdi->readbuffer_remaining;
    }
    // do the actual USB read
    while (offset < size && ret > 0) {
        ftdi->readbuffer_remaining = 0;
        ftdi->readbuffer_offset = 0;
        /* returns how much received */
        ret = usb_bulk_read (ftdi->usb_dev, ftdi->out_ep, ftdi->readbuffer, ftdi->readbuffer_chunksize, ftdi->usb_read_timeout);
        if (ret < 0)
            ftdi_error_return(ret, "usb bulk read failed");

        if (ret > 2) {
            // skip FTDI status bytes.
            // Maybe stored in the future to enable modem use
            num_of_chunks = ret / 64;
            chunk_remains = ret % 64;
            //printf("ret = %X, num_of_chunks = %X, chunk_remains = %X, readbuffer_offset = %X\n", ret, num_of_chunks, chunk_remains, ftdi->readbuffer_offset);

            ftdi->readbuffer_offset += 2;
            ret -= 2;

            if (ret > 62) {
                for (i = 1; i < num_of_chunks; i++)
                    memmove (ftdi->readbuffer+ftdi->readbuffer_offset+62*i,
                             ftdi->readbuffer+ftdi->readbuffer_offset+64*i,
                             62);
                if (chunk_remains > 2) {
                    memmove (ftdi->readbuffer+ftdi->readbuffer_offset+62*i,
                             ftdi->readbuffer+ftdi->readbuffer_offset+64*i,
                             chunk_remains-2);
                    ret -= 2*num_of_chunks;
                } else
                    ret -= 2*(num_of_chunks-1)+chunk_remains;
            }
        } else if (ret <= 2) {
            // no more data to read?
            return offset;
        }
        if (ret > 0) {
            // data still fits in buf?
            if (offset+ret <= size) {
                memcpy (buf+offset, ftdi->readbuffer+ftdi->readbuffer_offset, ret);
                //printf("buf[0] = %X, buf[1] = %X\n", buf[0], buf[1]);
                offset += ret;

                /* Did we read exactly the right amount of bytes? */
                if (offset == size)
                    //printf("read_data exact rem %d offset %d\n",
                    //ftdi->readbuffer_remaining, offset);
                    return offset;
            } else {
                // only copy part of the data or size <= readbuffer_chunksize
                int part_size = size-offset;
                memcpy (buf+offset, ftdi->readbuffer+ftdi->readbuffer_offset, part_size);

                ftdi->readbuffer_offset += part_size;
                ftdi->readbuffer_remaining = ret-part_size;
                offset += part_size;

                /* printf("Returning part: %d - size: %d - offset: %d - ret: %d - remaining: %d\n",
                part_size, size, offset, ret, ftdi->readbuffer_remaining); */

                return offset;
            }
        }
    }
    // never reached
    return -127;
}

/**
    Configure read buffer chunk size.
    Default is 4096.

    Automatically reallocates the buffer.

    \param ftdi pointer to ftdi_context
    \param chunksize Chunk size

    \retval 0: all fine
*/
int ftdi_read_data_set_chunksize(struct ftdi_context *ftdi, unsigned int chunksize)
{
    unsigned char *new_buf;

    // Invalidate all remaining data
    ftdi->readbuffer_offset = 0;
    ftdi->readbuffer_remaining = 0;

    if ((new_buf = (unsigned char *)realloc(ftdi->readbuffer, chunksize)) == NULL)
        ftdi_error_return(-1, "out of memory for readbuffer");

    ftdi->readbuffer = new_buf;
    ftdi->readbuffer_chunksize = chunksize;

    return 0;
}

/**
    Get read buffer chunk size.

    \param ftdi pointer to ftdi_context
    \param chunksize Pointer to store chunk size in

    \retval 0: all fine
*/
int ftdi_read_data_get_chunksize(struct ftdi_context *ftdi, unsigned int *chunksize)
{
    *chunksize = ftdi->readbuffer_chunksize;
    return 0;
}


/**
    Enable bitbang mode.

    For advanced bitbang modes of the FT2232C chip use ftdi_set_bitmode().

    \param ftdi pointer to ftdi_context
    \param bitmask Bitmask to configure lines.
           HIGH/ON value configures a line as output.

    \retval  0: all fine
    \retval -1: can't enable bitbang mode
*/
int ftdi_enable_bitbang(struct ftdi_context *ftdi, unsigned char bitmask)
{
    unsigned short usb_val;

    usb_val = bitmask; // low byte: bitmask
    /* FT2232C: Set bitbang_mode to 2 to enable SPI */
    usb_val |= (ftdi->bitbang_mode << 8);

    if (usb_control_msg(ftdi->usb_dev, 0x40, 0x0B, usb_val, ftdi->index, NULL, 0, ftdi->usb_write_timeout) != 0)
        ftdi_error_return(-1, "unable to enter bitbang mode. Perhaps not a BM type chip?");