UEFI Serial I/O Protocol

UEFI Spec. Ver.2.4

GUID
#define EFI_SERIAL_IO_PROTOCOL_GUID \
 {0xBB25CF6F,0xF1D4,0x11D2,0x9A,0x0C,0x00,0x90,\
 0x27,0x3F,0xC1,0xFD}

Revision Number
#define EFI_SERIAL_IO_PROTOCOL_REVISION 0x00010000

Protocol Interface Structure
typedef struct {
 UINT32 Revision;
 EFI_SERIAL_RESET Reset;
 EFI_SERIAL_SET_ATTRIBUTES SetAttributes;
 EFI_SERIAL_SET_CONTROL_BITS SetControl;
 EFI_SERIAL_GET_CONTROL_BITS GetControl;
 EFI_SERIAL_WRITE Write;
 EFI_SERIAL_READ Read;
 SERIAL_IO_MODE *Mode;
} EFI_SERIAL_IO_PROTOCOL;

Parameters
Revision The revision to which the EFI_SERIAL_IO_PROTOCOL
adheres. All future revisions must be backwards compatible. If a
future version is not back wards compatible, it is not the same
GUID.
Reset Resets the hardware device.
SetAttributes Sets communication parameters for a serial device. These
include the baud rate, receive FIFO depth, transmit/receive time
out, parity, data bits, and stop bit attributes.
SetControl Sets the control bits on a serial device. These include Request to
Send and Data Terminal Ready.
GetControl Reads the status of the control bits on a serial device. These
include Clear to Send, Data Set Ready, Ring Indicator, and
Carrier Detect.
Write Sends a buffer of characters to a serial device.
Read Receives a buffer of characters from a serial device.
Mode Pointer to SERIAL_IO_MODE data. Type SERIAL_IO_MODE
is defined in “Related Definitions” below.


Related Definitions

//*******************************************************
// SERIAL_IO_MODE
//*******************************************************
typedef struct {
UINT32 ControlMask;
 // current Attributes
 UINT32 Timeout;
 UINT64 BaudRate;
 UINT32 ReceiveFifoDepth;
 UINT32 DataBits;
 UINT32 Parity;
 UINT32 StopBits;
} SERIAL_IO_MODE;


//*******************************************************
// CONTROL BITS
//*******************************************************

// Read Only

#define EFI_SERIAL_CLEAR_TO_SEND 0x0010
#define EFI_SERIAL_DATA_SET_READY 0x0020
#define EFI_SERIAL_RING_INDICATE 0x0040
#define EFI_SERIAL_CARRIER_DETECT 0x0080
#define EFI_SERIAL_INPUT_BUFFER_EMPTY 0x0100   // See if the Receive FIFO is empty.
#define EFI_SERIAL_OUTPUT_BUFFER_EMPTY 0x0200 // See if the Transmit FIFO is empty

// Write Only

#define EFI_SERIAL_REQUEST_TO_SEND 0x0002
#define EFI_SERIAL_DATA_TERMINAL_READY 0x0001

// Read Write
#define EFI_SERIAL_HARDWARE_LOOPBACK_ENABLE 0x1000
#define EFI_SERIAL_SOFTWARE_LOOPBACK_ENABLE 0x2000
#define EFI_SERIAL_HARDWARE_FLOW_CONTROL_ENABLE 0x4000

串列埠的原理與應用

1.可透過GetControl function查看EFI_SERIAL_INPUT_BUFFER_EMPTY決定目前有無資料被接收,若有資料,則利用Read function讀進來

ReceiveFifoDepth The requested depth of the FIFO on the receive side of the serial
interface. A ReceiveFifoDepth value of 0 will use the
device’s default FIFO depth

Timeout The requested time out for a single character in microseconds.
This timeout applies to both the transmit and receive side of the
interface. A Timeout value of 0 will use the device’s default
time out value.

設定組態

  EFI_PARITY_TYPE         Parity=NoParity;
  EFI_STOP_BITS_TYPE      StopBits=OneStopBit;
  UINTN                   BaudRate=9600;
  UINTN                   DataBits=8;

 Status = SerialIo->SetAttributes (
                              SerialIo,
                              (UINT64) BaudRate, //9600
                              0, //use default
                              0, //use default
                              Parity, // N 
                              (UINT8) DataBits, //8
                              StopBits //1
                             );

檢查有無資料進來

  UINT32 SerialControl;

  Status = SerialIo->GetControl (
                 SerialIo,
                 &SerialControl);
  if (!EFI_ERROR (Status)) {
    if ((SerialControl & EFI_SERIAL_INPUT_BUFFER_EMPTY) != 0) {
      Status = EFI_NOT_READY;
    } else {
      Status = EFI_SUCCESS;
    }
  }