IOCTL_SERIAL_GET_LINE_CONTROL control code
The IOCTL_SERIAL_GET_LINE_CONTROL request returns information about the line control set for a serial device. The line control parameters include the number of stop bits, the number of data bits, and the parity.
To configure the line control, a client can use an IOCTL_SERIAL_SET_LINE_CONTROL request.
For information about valid line control register settings, see SERIAL_LINE_CONTROL.
The Parameters.DeviceIoControl.OutputBufferLength member is set to the size, in bytes, of a SERIAL_LINE_CONTROL structure.
The AssociatedIrp.SystemBuffer member points to a client-allocated SERIAL_LINE_CONTROL structure that the serial controller driver uses to output information about the line control configuration.
If the request is successful, the Information member is set to the size, in bytes, of a SERIAL_LINE_CONTROL structure. Otherwise, the Information member is set to zero.
The Status member is set to one of the Generic Status Values for Serial Device Control Requests.