Armadilloフォーラム

        /*
         * Break handling
         */
        case TIOCSBRK:  /* Turn break on, unconditionally */
                if (tty->ops->break_ctl)
                        return tty->ops->break_ctl(tty, -1);
                return 0;
        case TIOCCBRK:  /* Turn break off, unconditionally */
                if (tty->ops->break_ctl)
                        return tty->ops->break_ctl(tty, 0);
                return 0;
        case TCSBRK:   /* SVID version: non-zero arg --> no break */
                /* non-zero arg means wait for all output data
                 * to be sent (performed above) but don't send break.
                 * This is used by the tcdrain() termios function.
                 */
                if (!arg)
                        return send_break(tty, 250);
                return 0;
        case TCSBRKP:   /* support for POSIX tcsendbreak() */
                return send_break(tty, arg ? arg*100 : 250);

static struct usb_serial_driver ftdi_sio_device = {
        .driver = {
                .owner =        THIS_MODULE,
                .name =         "ftdi_sio",
        },
        .description =          "FTDI USB Serial Device",
   (途中省略)
        .break_ctl =            ftdi_break_ctl,
};

static void ftdi_break_ctl(struct tty_struct *tty, int break_state)
{
        struct usb_serial_port *port = tty->driver_data;
        struct ftdi_private *priv = usb_get_serial_port_data(port);
        __u16 urb_value;
 
        /* break_state = -1 to turn on break, and 0 to turn off break */
        /* see drivers/char/tty_io.c to see it used */
        /* last_set_data_urb_value NEVER has the break bit set in it */
 
        if (break_state)
                urb_value = priv->last_set_data_urb_value | FTDI_SIO_SET_BREAK;
        else
                urb_value = priv->last_set_data_urb_value;
 
        if (usb_control_msg(port->serial->dev,
                        usb_sndctrlpipe(port->serial->dev, 0),
                        FTDI_SIO_SET_DATA_REQUEST,
                        FTDI_SIO_SET_DATA_REQUEST_TYPE,
                        urb_value , priv->interface,
                        NULL, 0, WDR_TIMEOUT) < 0) {
                dev_err(&port->dev, "%s FAILED to enable/disable break state "
                        "(state was %d)\n", __func__, break_state);
        }
 
        dbg("%s break state is %d - urb is %d", __func__,
                                                break_state, urb_value);
 
}

static void cp210x_break_ctl (struct tty_struct *tty, int break_state)
{
        struct usb_serial_port *port = tty->driver_data;
        unsigned int state;
 
        dbg("%s - port %d", __func__, port->number);
        if (break_state == 0)
                state = BREAK_OFF;
        else
                state = BREAK_ON;
        dbg("%s - turning break %s", __func__,
                        state == BREAK_OFF ? "off" : "on");
        cp210x_set_config(port, CP210X_SET_BREAK, &state, 2);
}
 
static int cp210x_set_config(struct usb_serial_port *port, u8 request,
                unsigned int *data, int size)
{
   (省略)
}