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-rw-r--r--OvmfPkg/LoongArchVirt/Library/EarlyFdtSerialPortLib16550/EarlyFdtSerialPortLib16550.c819
-rw-r--r--OvmfPkg/LoongArchVirt/Library/EarlyFdtSerialPortLib16550/EarlyFdtSerialPortLib16550.inf47
2 files changed, 866 insertions, 0 deletions
diff --git a/OvmfPkg/LoongArchVirt/Library/EarlyFdtSerialPortLib16550/EarlyFdtSerialPortLib16550.c b/OvmfPkg/LoongArchVirt/Library/EarlyFdtSerialPortLib16550/EarlyFdtSerialPortLib16550.c
new file mode 100644
index 0000000..9e6e3d6
--- /dev/null
+++ b/OvmfPkg/LoongArchVirt/Library/EarlyFdtSerialPortLib16550/EarlyFdtSerialPortLib16550.c
@@ -0,0 +1,819 @@
+/** @file
+ 16550 UART Serial Port library functions
+
+ Copyright (c) 2024, Loongson Technology Corporation Limited. All rights reserved.<BR>
+
+ SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include <Base.h>
+#include <Library/BaseLib.h>
+#include <Library/FdtSerialPortAddressLib.h>
+#include <Library/IoLib.h>
+#include <Library/PcdLib.h>
+#include <Library/SerialPortLib.h>
+
+//
+// PCI Defintions.
+//
+#define PCI_BRIDGE_32_BIT_IO_SPACE 0x01
+
+//
+// 16550 UART register offsets and bitfields
+//
+#define R_UART_RXBUF 0 // LCR_DLAB = 0
+#define R_UART_TXBUF 0 // LCR_DLAB = 0
+#define R_UART_BAUD_LOW 0 // LCR_DLAB = 1
+#define R_UART_BAUD_HIGH 1 // LCR_DLAB = 1
+#define R_UART_IER 1 // LCR_DLAB = 0
+#define R_UART_FCR 2
+#define B_UART_FCR_FIFOE BIT0
+#define B_UART_FCR_FIFO64 BIT5
+#define R_UART_LCR 3
+#define B_UART_LCR_DLAB BIT7
+#define R_UART_MCR 4
+#define B_UART_MCR_DTRC BIT0
+#define B_UART_MCR_RTS BIT1
+#define R_UART_LSR 5
+#define B_UART_LSR_RXRDY BIT0
+#define B_UART_LSR_TXRDY BIT5
+#define B_UART_LSR_TEMT BIT6
+#define R_UART_MSR 6
+#define B_UART_MSR_CTS BIT4
+#define B_UART_MSR_DSR BIT5
+#define B_UART_MSR_RI BIT6
+#define B_UART_MSR_DCD BIT7
+
+/**
+ Read an 8-bit 16550 register. If PcdSerialUseMmio is TRUE, then the value is read from
+ MMIO space. If PcdSerialUseMmio is FALSE, then the value is read from I/O space. The
+ parameter Offset is added to the base address of the 16550 registers that is specified
+ by PcdSerialRegisterBase. PcdSerialRegisterAccessWidth specifies the MMIO space access
+ width and defaults to 8 bit access, and supports 8 or 32 bit access.
+
+ @param Base The base address register of UART device.
+ @param Offset The offset of the 16550 register to read.
+
+ @return The value read from the 16550 register.
+**/
+STATIC
+UINT8
+SerialPortReadRegister (
+ UINTN Base,
+ UINTN Offset
+ )
+{
+ if (PcdGetBool (PcdSerialUseMmio)) {
+ if (PcdGet8 (PcdSerialRegisterAccessWidth) == 32) {
+ return (UINT8)MmioRead32 (Base + Offset * PcdGet32 (PcdSerialRegisterStride));
+ }
+
+ return MmioRead8 (Base + Offset * PcdGet32 (PcdSerialRegisterStride));
+ } else {
+ return IoRead8 (Base + Offset * PcdGet32 (PcdSerialRegisterStride));
+ }
+}
+
+/**
+ Write an 8-bit 16550 register. If PcdSerialUseMmio is TRUE, then the value is written to
+ MMIO space. If PcdSerialUseMmio is FALSE, then the value is written to I/O space. The
+ parameter Offset is added to the base address of the 16550 registers that is specified
+ by PcdSerialRegisterBase. PcdSerialRegisterAccessWidth specifies the MMIO space access
+ width and defaults to 8 bit access, and supports 8 or 32 bit access.
+
+ @param Base The base address register of UART device.
+ @param Offset The offset of the 16550 register to write.
+ @param Value The value to write to the 16550 register specified by Offset.
+
+ @return The value written to the 16550 register.
+**/
+STATIC
+UINT8
+SerialPortWriteRegister (
+ UINTN Base,
+ UINTN Offset,
+ UINT8 Value
+ )
+{
+ if (PcdGetBool (PcdSerialUseMmio)) {
+ if (PcdGet8 (PcdSerialRegisterAccessWidth) == 32) {
+ return (UINT8)MmioWrite32 (Base + Offset * PcdGet32 (PcdSerialRegisterStride), (UINT8)Value);
+ }
+
+ return MmioWrite8 (Base + Offset * PcdGet32 (PcdSerialRegisterStride), Value);
+ } else {
+ return IoWrite8 (Base + Offset * PcdGet32 (PcdSerialRegisterStride), Value);
+ }
+}
+
+/**
+ Retrieve the I/O or MMIO base address register for the PCI UART device.
+
+ This function assumes Root Bus Numer is Zero, and enables I/O and MMIO in PCI UART
+ Device if they are not already enabled.
+
+ @return The base address register of the UART device.
+**/
+STATIC
+UINTN
+GetSerialRegisterBase (
+ VOID
+ )
+{
+ VOID *Base;
+ RETURN_STATUS Status;
+ UINT64 SerialConsoleAddress;
+
+ Base = (VOID *)(UINTN)PcdGet64 (PcdDeviceTreeInitialBaseAddress);
+ Status = FdtSerialGetConsolePort (Base, &SerialConsoleAddress);
+ if (RETURN_ERROR (Status)) {
+ return (UINTN)0;
+ }
+
+ return SerialConsoleAddress;
+}
+
+/**
+ Return whether the hardware flow control signal allows writing.
+
+ @param SerialRegisterBase The base address register of UART device.
+
+ @retval TRUE The serial port is writable.
+ @retval FALSE The serial port is not writable.
+**/
+STATIC
+BOOLEAN
+SerialPortWritable (
+ UINTN SerialRegisterBase
+ )
+{
+ if (PcdGetBool (PcdSerialUseHardwareFlowControl)) {
+ if (PcdGetBool (PcdSerialDetectCable)) {
+ //
+ // Wait for both DSR and CTS to be set
+ // DSR is set if a cable is connected.
+ // CTS is set if it is ok to transmit data
+ //
+ // DSR CTS Description Action
+ // === === ======================================== ========
+ // 0 0 No cable connected. Wait
+ // 0 1 No cable connected. Wait
+ // 1 0 Cable connected, but not clear to send. Wait
+ // 1 1 Cable connected, and clear to send. Transmit
+ //
+ return (BOOLEAN)((SerialPortReadRegister (SerialRegisterBase, R_UART_MSR) & (B_UART_MSR_DSR | B_UART_MSR_CTS)) == (B_UART_MSR_DSR | B_UART_MSR_CTS));
+ } else {
+ //
+ // Wait for both DSR and CTS to be set OR for DSR to be clear.
+ // DSR is set if a cable is connected.
+ // CTS is set if it is ok to transmit data
+ //
+ // DSR CTS Description Action
+ // === === ======================================== ========
+ // 0 0 No cable connected. Transmit
+ // 0 1 No cable connected. Transmit
+ // 1 0 Cable connected, but not clear to send. Wait
+ // 1 1 Cable connected, and clar to send. Transmit
+ //
+ return (BOOLEAN)((SerialPortReadRegister (SerialRegisterBase, R_UART_MSR) & (B_UART_MSR_DSR | B_UART_MSR_CTS)) != (B_UART_MSR_DSR));
+ }
+ }
+
+ return TRUE;
+}
+
+/**
+ Initialize the serial device hardware.
+
+ If no initialization is required, then return RETURN_SUCCESS.
+ If the serial device was successfully initialized, then return RETURN_SUCCESS.
+ If the serial device could not be initialized, then return RETURN_DEVICE_ERROR.
+
+ @retval RETURN_SUCCESS The serial device was initialized.
+ @retval RETURN_DEVICE_ERROR The serial device could not be initialized.
+**/
+RETURN_STATUS
+EFIAPI
+SerialPortInitialize (
+ VOID
+ )
+{
+ UINTN SerialRegisterBase;
+ UINT32 Divisor;
+ UINT32 CurrentDivisor;
+ BOOLEAN Initialized;
+
+ //
+ // Calculate divisor for baud generator
+ // Ref_Clk_Rate / Baud_Rate / 16
+ //
+ Divisor = PcdGet32 (PcdSerialClockRate) / (PcdGet32 (PcdSerialBaudRate) * 16);
+ if ((PcdGet32 (PcdSerialClockRate) % (PcdGet32 (PcdSerialBaudRate) * 16)) >= PcdGet32 (PcdSerialBaudRate) * 8) {
+ Divisor++;
+ }
+
+ //
+ // Get the base address of the serial port in either I/O or MMIO space
+ //
+ SerialRegisterBase = GetSerialRegisterBase ();
+ if (SerialRegisterBase == 0) {
+ return RETURN_DEVICE_ERROR;
+ }
+
+ //
+ // See if the serial port is already initialized
+ //
+ Initialized = TRUE;
+ if ((SerialPortReadRegister (SerialRegisterBase, R_UART_LCR) & 0x3F) != (PcdGet8 (PcdSerialLineControl) & 0x3F)) {
+ Initialized = FALSE;
+ }
+
+ SerialPortWriteRegister (SerialRegisterBase, R_UART_LCR, (UINT8)(SerialPortReadRegister (SerialRegisterBase, R_UART_LCR) | B_UART_LCR_DLAB));
+ CurrentDivisor = SerialPortReadRegister (SerialRegisterBase, R_UART_BAUD_HIGH) << 8;
+ CurrentDivisor |= (UINT32)SerialPortReadRegister (SerialRegisterBase, R_UART_BAUD_LOW);
+ SerialPortWriteRegister (SerialRegisterBase, R_UART_LCR, (UINT8)(SerialPortReadRegister (SerialRegisterBase, R_UART_LCR) & ~B_UART_LCR_DLAB));
+ if (CurrentDivisor != Divisor) {
+ Initialized = FALSE;
+ }
+
+ if (Initialized) {
+ return RETURN_SUCCESS;
+ }
+
+ //
+ // Wait for the serial port to be ready.
+ // Verify that both the transmit FIFO and the shift register are empty.
+ //
+ while ((SerialPortReadRegister (SerialRegisterBase, R_UART_LSR) & (B_UART_LSR_TEMT | B_UART_LSR_TXRDY)) != (B_UART_LSR_TEMT | B_UART_LSR_TXRDY)) {
+ }
+
+ //
+ // Configure baud rate
+ //
+ SerialPortWriteRegister (SerialRegisterBase, R_UART_LCR, B_UART_LCR_DLAB);
+ SerialPortWriteRegister (SerialRegisterBase, R_UART_BAUD_HIGH, (UINT8)(Divisor >> 8));
+ SerialPortWriteRegister (SerialRegisterBase, R_UART_BAUD_LOW, (UINT8)(Divisor & 0xff));
+
+ //
+ // Clear DLAB and configure Data Bits, Parity, and Stop Bits.
+ // Strip reserved bits from PcdSerialLineControl
+ //
+ SerialPortWriteRegister (SerialRegisterBase, R_UART_LCR, (UINT8)(PcdGet8 (PcdSerialLineControl) & 0x3F));
+
+ //
+ // Enable and reset FIFOs
+ // Strip reserved bits from PcdSerialFifoControl
+ //
+ SerialPortWriteRegister (SerialRegisterBase, R_UART_FCR, 0x00);
+ SerialPortWriteRegister (SerialRegisterBase, R_UART_FCR, (UINT8)(PcdGet8 (PcdSerialFifoControl) & (B_UART_FCR_FIFOE | B_UART_FCR_FIFO64)));
+
+ //
+ // Set FIFO Polled Mode by clearing IER after setting FCR
+ //
+ SerialPortWriteRegister (SerialRegisterBase, R_UART_IER, 0x00);
+
+ //
+ // Put Modem Control Register(MCR) into its reset state of 0x00.
+ //
+ SerialPortWriteRegister (SerialRegisterBase, R_UART_MCR, 0x00);
+
+ return RETURN_SUCCESS;
+}
+
+/**
+ Write data from buffer to serial device.
+
+ Writes NumberOfBytes data bytes from Buffer to the serial device.
+ The number of bytes actually written to the serial device is returned.
+ If the return value is less than NumberOfBytes, then the write operation failed.
+
+ If Buffer is NULL, then ASSERT().
+
+ If NumberOfBytes is zero, then return 0.
+
+ @param Buffer Pointer to the data buffer to be written.
+ @param NumberOfBytes Number of bytes to written to the serial device.
+
+ @retval 0 NumberOfBytes is 0.
+ @retval >0 The number of bytes written to the serial device.
+ If this value is less than NumberOfBytes, then the write operation failed.
+
+**/
+UINTN
+EFIAPI
+SerialPortWrite (
+ IN UINT8 *Buffer,
+ IN UINTN NumberOfBytes
+ )
+{
+ UINTN SerialRegisterBase;
+ UINTN Result;
+ UINTN Index;
+ UINTN FifoSize;
+
+ if (Buffer == NULL) {
+ return 0;
+ }
+
+ SerialRegisterBase = GetSerialRegisterBase ();
+ if (SerialRegisterBase == 0) {
+ return 0;
+ }
+
+ if (NumberOfBytes == 0) {
+ //
+ // Flush the hardware
+ //
+
+ //
+ // Wait for both the transmit FIFO and shift register empty.
+ //
+ while ((SerialPortReadRegister (SerialRegisterBase, R_UART_LSR) & (B_UART_LSR_TEMT | B_UART_LSR_TXRDY)) != (B_UART_LSR_TEMT | B_UART_LSR_TXRDY)) {
+ }
+
+ //
+ // Wait for the hardware flow control signal
+ //
+ while (!SerialPortWritable (SerialRegisterBase)) {
+ }
+
+ return 0;
+ }
+
+ //
+ // Compute the maximum size of the Tx FIFO
+ //
+ FifoSize = 1;
+ if ((PcdGet8 (PcdSerialFifoControl) & B_UART_FCR_FIFOE) != 0) {
+ if ((PcdGet8 (PcdSerialFifoControl) & B_UART_FCR_FIFO64) == 0) {
+ FifoSize = 16;
+ } else {
+ FifoSize = PcdGet32 (PcdSerialExtendedTxFifoSize);
+ }
+ }
+
+ Result = NumberOfBytes;
+ while (NumberOfBytes != 0) {
+ //
+ // Wait for the serial port to be ready, to make sure both the transmit FIFO
+ // and shift register empty.
+ //
+ while ((SerialPortReadRegister (SerialRegisterBase, R_UART_LSR) & (B_UART_LSR_TEMT | B_UART_LSR_TXRDY)) != (B_UART_LSR_TEMT | B_UART_LSR_TXRDY)) {
+ }
+
+ //
+ // Fill then entire Tx FIFO
+ //
+ for (Index = 0; Index < FifoSize && NumberOfBytes != 0; Index++, NumberOfBytes--, Buffer++) {
+ //
+ // Wait for the hardware flow control signal
+ //
+ while (!SerialPortWritable (SerialRegisterBase)) {
+ }
+
+ //
+ // Write byte to the transmit buffer.
+ //
+ SerialPortWriteRegister (SerialRegisterBase, R_UART_TXBUF, *Buffer);
+ }
+ }
+
+ return Result;
+}
+
+/**
+ Reads data from a serial device into a buffer.
+
+ @param Buffer Pointer to the data buffer to store the data read from the serial device.
+ @param NumberOfBytes Number of bytes to read from the serial device.
+
+ @retval 0 NumberOfBytes is 0.
+ @retval >0 The number of bytes read from the serial device.
+ If this value is less than NumberOfBytes, then the read operation failed.
+**/
+UINTN
+EFIAPI
+SerialPortRead (
+ OUT UINT8 *Buffer,
+ IN UINTN NumberOfBytes
+ )
+{
+ UINTN SerialRegisterBase;
+ UINTN Result;
+ UINT8 Mcr;
+
+ if (NULL == Buffer) {
+ return 0;
+ }
+
+ SerialRegisterBase = GetSerialRegisterBase ();
+ if (SerialRegisterBase == 0) {
+ return 0;
+ }
+
+ Mcr = (UINT8)(SerialPortReadRegister (SerialRegisterBase, R_UART_MCR) & ~B_UART_MCR_RTS);
+
+ for (Result = 0; NumberOfBytes-- != 0; Result++, Buffer++) {
+ //
+ // Wait for the serial port to have some data.
+ //
+ while ((SerialPortReadRegister (SerialRegisterBase, R_UART_LSR) & B_UART_LSR_RXRDY) == 0) {
+ if (PcdGetBool (PcdSerialUseHardwareFlowControl)) {
+ //
+ // Set RTS to let the peer send some data
+ //
+ SerialPortWriteRegister (SerialRegisterBase, R_UART_MCR, (UINT8)(Mcr | B_UART_MCR_RTS));
+ }
+ }
+
+ if (PcdGetBool (PcdSerialUseHardwareFlowControl)) {
+ //
+ // Clear RTS to prevent peer from sending data
+ //
+ SerialPortWriteRegister (SerialRegisterBase, R_UART_MCR, Mcr);
+ }
+
+ //
+ // Read byte from the receive buffer.
+ //
+ *Buffer = SerialPortReadRegister (SerialRegisterBase, R_UART_RXBUF);
+ }
+
+ return Result;
+}
+
+/**
+ Polls a serial device to see if there is any data waiting to be read.
+
+ Polls aserial device to see if there is any data waiting to be read.
+ If there is data waiting to be read from the serial device, then TRUE is returned.
+ If there is no data waiting to be read from the serial device, then FALSE is returned.
+
+ @retval TRUE Data is waiting to be read from the serial device.
+ @retval FALSE There is no data waiting to be read from the serial device.
+**/
+BOOLEAN
+EFIAPI
+SerialPortPoll (
+ VOID
+ )
+{
+ UINTN SerialRegisterBase;
+
+ SerialRegisterBase = GetSerialRegisterBase ();
+ if (SerialRegisterBase == 0) {
+ return FALSE;
+ }
+
+ //
+ // Read the serial port status
+ //
+ if ((SerialPortReadRegister (SerialRegisterBase, R_UART_LSR) & B_UART_LSR_RXRDY) != 0) {
+ if (PcdGetBool (PcdSerialUseHardwareFlowControl)) {
+ //
+ // Clear RTS to prevent peer from sending data
+ //
+ SerialPortWriteRegister (SerialRegisterBase, R_UART_MCR, (UINT8)(SerialPortReadRegister (SerialRegisterBase, R_UART_MCR) & ~B_UART_MCR_RTS));
+ }
+
+ return TRUE;
+ }
+
+ if (PcdGetBool (PcdSerialUseHardwareFlowControl)) {
+ //
+ // Set RTS to let the peer send some data
+ //
+ SerialPortWriteRegister (SerialRegisterBase, R_UART_MCR, (UINT8)(SerialPortReadRegister (SerialRegisterBase, R_UART_MCR) | B_UART_MCR_RTS));
+ }
+
+ return FALSE;
+}
+
+/**
+ Sets the control bits on a serial device.
+
+ @param Control Sets the bits of Control that are settable.
+
+ @retval RETURN_SUCCESS The new control bits were set on the serial device.
+ @retval RETURN_UNSUPPORTED The serial device does not support this operation.
+ @retval RETURN_DEVICE_ERROR The serial device is not functioning correctly.
+**/
+RETURN_STATUS
+EFIAPI
+SerialPortSetControl (
+ IN UINT32 Control
+ )
+{
+ UINTN SerialRegisterBase;
+ UINT8 Mcr;
+
+ //
+ // First determine the parameter is invalid.
+ //
+ if ((Control & (~(EFI_SERIAL_REQUEST_TO_SEND | EFI_SERIAL_DATA_TERMINAL_READY |
+ EFI_SERIAL_HARDWARE_FLOW_CONTROL_ENABLE))) != 0)
+ {
+ return RETURN_UNSUPPORTED;
+ }
+
+ SerialRegisterBase = GetSerialRegisterBase ();
+ if (SerialRegisterBase == 0) {
+ return RETURN_UNSUPPORTED;
+ }
+
+ //
+ // Read the Modem Control Register.
+ //
+ Mcr = SerialPortReadRegister (SerialRegisterBase, R_UART_MCR);
+ Mcr &= (~(B_UART_MCR_DTRC | B_UART_MCR_RTS));
+
+ if ((Control & EFI_SERIAL_DATA_TERMINAL_READY) == EFI_SERIAL_DATA_TERMINAL_READY) {
+ Mcr |= B_UART_MCR_DTRC;
+ }
+
+ if ((Control & EFI_SERIAL_REQUEST_TO_SEND) == EFI_SERIAL_REQUEST_TO_SEND) {
+ Mcr |= B_UART_MCR_RTS;
+ }
+
+ //
+ // Write the Modem Control Register.
+ //
+ SerialPortWriteRegister (SerialRegisterBase, R_UART_MCR, Mcr);
+
+ return RETURN_SUCCESS;
+}
+
+/**
+ Retrieve the status of the control bits on a serial device.
+
+ @param Control A pointer to return the current control signals from the serial device.
+
+ @retval RETURN_SUCCESS The control bits were read from the serial device.
+ @retval RETURN_UNSUPPORTED The serial device does not support this operation.
+ @retval RETURN_DEVICE_ERROR The serial device is not functioning correctly.
+**/
+RETURN_STATUS
+EFIAPI
+SerialPortGetControl (
+ OUT UINT32 *Control
+ )
+{
+ UINTN SerialRegisterBase;
+ UINT8 Msr;
+ UINT8 Mcr;
+ UINT8 Lsr;
+
+ SerialRegisterBase = GetSerialRegisterBase ();
+ if (SerialRegisterBase == 0) {
+ return RETURN_UNSUPPORTED;
+ }
+
+ *Control = 0;
+
+ //
+ // Read the Modem Status Register.
+ //
+ Msr = SerialPortReadRegister (SerialRegisterBase, R_UART_MSR);
+
+ if ((Msr & B_UART_MSR_CTS) == B_UART_MSR_CTS) {
+ *Control |= EFI_SERIAL_CLEAR_TO_SEND;
+ }
+
+ if ((Msr & B_UART_MSR_DSR) == B_UART_MSR_DSR) {
+ *Control |= EFI_SERIAL_DATA_SET_READY;
+ }
+
+ if ((Msr & B_UART_MSR_RI) == B_UART_MSR_RI) {
+ *Control |= EFI_SERIAL_RING_INDICATE;
+ }
+
+ if ((Msr & B_UART_MSR_DCD) == B_UART_MSR_DCD) {
+ *Control |= EFI_SERIAL_CARRIER_DETECT;
+ }
+
+ //
+ // Read the Modem Control Register.
+ //
+ Mcr = SerialPortReadRegister (SerialRegisterBase, R_UART_MCR);
+
+ if ((Mcr & B_UART_MCR_DTRC) == B_UART_MCR_DTRC) {
+ *Control |= EFI_SERIAL_DATA_TERMINAL_READY;
+ }
+
+ if ((Mcr & B_UART_MCR_RTS) == B_UART_MCR_RTS) {
+ *Control |= EFI_SERIAL_REQUEST_TO_SEND;
+ }
+
+ if (PcdGetBool (PcdSerialUseHardwareFlowControl)) {
+ *Control |= EFI_SERIAL_HARDWARE_FLOW_CONTROL_ENABLE;
+ }
+
+ //
+ // Read the Line Status Register.
+ //
+ Lsr = SerialPortReadRegister (SerialRegisterBase, R_UART_LSR);
+
+ if ((Lsr & (B_UART_LSR_TEMT | B_UART_LSR_TXRDY)) == (B_UART_LSR_TEMT | B_UART_LSR_TXRDY)) {
+ *Control |= EFI_SERIAL_OUTPUT_BUFFER_EMPTY;
+ }
+
+ if ((Lsr & B_UART_LSR_RXRDY) == 0) {
+ *Control |= EFI_SERIAL_INPUT_BUFFER_EMPTY;
+ }
+
+ return RETURN_SUCCESS;
+}
+
+/**
+ Sets the baud rate, receive FIFO depth, transmit/receice time out, parity,
+ data bits, and stop bits on a serial device.
+
+ @param BaudRate The requested baud rate. A BaudRate value of 0 will use the
+ device's default interface speed.
+ On output, the value actually set.
+ @param ReveiveFifoDepth 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.
+ On output, the value actually set.
+ @param 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.
+ On output, the value actually set.
+ @param Parity The type of parity to use on this serial device. A Parity value of
+ DefaultParity will use the device's default parity value.
+ On output, the value actually set.
+ @param DataBits The number of data bits to use on the serial device. A DataBits
+ vaule of 0 will use the device's default data bit setting.
+ On output, the value actually set.
+ @param StopBits The number of stop bits to use on this serial device. A StopBits
+ value of DefaultStopBits will use the device's default number of
+ stop bits.
+ On output, the value actually set.
+
+ @retval RETURN_SUCCESS The new attributes were set on the serial device.
+ @retval RETURN_UNSUPPORTED The serial device does not support this operation.
+ @retval RETURN_INVALID_PARAMETER One or more of the attributes has an unsupported value.
+ @retval RETURN_DEVICE_ERROR The serial device is not functioning correctly.
+**/
+RETURN_STATUS
+EFIAPI
+SerialPortSetAttributes (
+ IN OUT UINT64 *BaudRate,
+ IN OUT UINT32 *ReceiveFifoDepth,
+ IN OUT UINT32 *Timeout,
+ IN OUT EFI_PARITY_TYPE *Parity,
+ IN OUT UINT8 *DataBits,
+ IN OUT EFI_STOP_BITS_TYPE *StopBits
+ )
+{
+ UINTN SerialRegisterBase;
+ UINT32 SerialBaudRate;
+ UINTN Divisor;
+ UINT8 Lcr;
+ UINT8 LcrData;
+ UINT8 LcrParity;
+ UINT8 LcrStop;
+
+ SerialRegisterBase = GetSerialRegisterBase ();
+ if (SerialRegisterBase == 0) {
+ return RETURN_UNSUPPORTED;
+ }
+
+ //
+ // Check for default settings and fill in actual values.
+ //
+ if (*BaudRate == 0) {
+ *BaudRate = PcdGet32 (PcdSerialBaudRate);
+ }
+
+ SerialBaudRate = (UINT32)*BaudRate;
+
+ if (*DataBits == 0) {
+ LcrData = (UINT8)(PcdGet8 (PcdSerialLineControl) & 0x3);
+ *DataBits = LcrData + 5;
+ } else {
+ if ((*DataBits < 5) || (*DataBits > 8)) {
+ return RETURN_INVALID_PARAMETER;
+ }
+
+ //
+ // Map 5..8 to 0..3
+ //
+ LcrData = (UINT8)(*DataBits - (UINT8)5);
+ }
+
+ if (*Parity == DefaultParity) {
+ LcrParity = (UINT8)((PcdGet8 (PcdSerialLineControl) >> 3) & 0x7);
+ switch (LcrParity) {
+ case 0:
+ *Parity = NoParity;
+ break;
+
+ case 3:
+ *Parity = EvenParity;
+ break;
+
+ case 1:
+ *Parity = OddParity;
+ break;
+
+ case 7:
+ *Parity = SpaceParity;
+ break;
+
+ case 5:
+ *Parity = MarkParity;
+ break;
+
+ default:
+ break;
+ }
+ } else {
+ switch (*Parity) {
+ case NoParity:
+ LcrParity = 0;
+ break;
+
+ case EvenParity:
+ LcrParity = 3;
+ break;
+
+ case OddParity:
+ LcrParity = 1;
+ break;
+
+ case SpaceParity:
+ LcrParity = 7;
+ break;
+
+ case MarkParity:
+ LcrParity = 5;
+ break;
+
+ default:
+ return RETURN_INVALID_PARAMETER;
+ }
+ }
+
+ if (*StopBits == DefaultStopBits) {
+ LcrStop = (UINT8)((PcdGet8 (PcdSerialLineControl) >> 2) & 0x1);
+ switch (LcrStop) {
+ case 0:
+ *StopBits = OneStopBit;
+ break;
+
+ case 1:
+ if (*DataBits == 5) {
+ *StopBits = OneFiveStopBits;
+ } else {
+ *StopBits = TwoStopBits;
+ }
+
+ break;
+
+ default:
+ break;
+ }
+ } else {
+ switch (*StopBits) {
+ case OneStopBit:
+ LcrStop = 0;
+ break;
+
+ case OneFiveStopBits:
+ case TwoStopBits:
+ LcrStop = 1;
+ break;
+
+ default:
+ return RETURN_INVALID_PARAMETER;
+ }
+ }
+
+ //
+ // Calculate divisor for baud generator
+ // Ref_Clk_Rate / Baud_Rate / 16
+ //
+ Divisor = PcdGet32 (PcdSerialClockRate) / (SerialBaudRate * 16);
+ if ((PcdGet32 (PcdSerialClockRate) % (SerialBaudRate * 16)) >= SerialBaudRate * 8) {
+ Divisor++;
+ }
+
+ //
+ // Configure baud rate
+ //
+ SerialPortWriteRegister (SerialRegisterBase, R_UART_LCR, B_UART_LCR_DLAB);
+ SerialPortWriteRegister (SerialRegisterBase, R_UART_BAUD_HIGH, (UINT8)(Divisor >> 8));
+ SerialPortWriteRegister (SerialRegisterBase, R_UART_BAUD_LOW, (UINT8)(Divisor & 0xff));
+
+ //
+ // Clear DLAB and configure Data Bits, Parity, and Stop Bits.
+ // Strip reserved bits from line control value
+ //
+ Lcr = (UINT8)((LcrParity << 3) | (LcrStop << 2) | LcrData);
+ SerialPortWriteRegister (SerialRegisterBase, R_UART_LCR, (UINT8)(Lcr & 0x3F));
+
+ return RETURN_SUCCESS;
+}
diff --git a/OvmfPkg/LoongArchVirt/Library/EarlyFdtSerialPortLib16550/EarlyFdtSerialPortLib16550.inf b/OvmfPkg/LoongArchVirt/Library/EarlyFdtSerialPortLib16550/EarlyFdtSerialPortLib16550.inf
new file mode 100644
index 0000000..76a6bd0
--- /dev/null
+++ b/OvmfPkg/LoongArchVirt/Library/EarlyFdtSerialPortLib16550/EarlyFdtSerialPortLib16550.inf
@@ -0,0 +1,47 @@
+## @file
+# SerialPortLib instance for 16550 UART.
+#
+# Copyright (c) 2024, Loongson Technology Corporation Limited. All rights reserved.<BR>
+#
+# SPDX-License-Identifier: BSD-2-Clause-Patent
+#
+##
+
+[Defines]
+ INF_VERSION = 1.29
+ BASE_NAME = EarlySerialPortLib16550
+ FILE_GUID = f4fb883d-8138-4f29-bb0c-c574e9312c74
+ MODULE_TYPE = BASE
+ VERSION_STRING = 1.1
+ LIBRARY_CLASS = SerialPortLib
+
+[Packages]
+ EmbeddedPkg/EmbeddedPkg.dec
+ MdePkg/MdePkg.dec
+ MdeModulePkg/MdeModulePkg.dec
+ OvmfPkg/OvmfPkg.dec
+
+[LibraryClasses]
+ BaseLib
+ FdtSerialPortAddressLib
+ IoLib
+ PcdLib
+ SerialPortLib
+
+[Sources]
+ EarlyFdtSerialPortLib16550.c
+
+[Pcd]
+ gEfiMdeModulePkgTokenSpaceGuid.PcdSerialRegisterAccessWidth ## SOMETIMES_CONSUMES
+ gEfiMdeModulePkgTokenSpaceGuid.PcdSerialUseMmio ## CONSUMES
+ gEfiMdeModulePkgTokenSpaceGuid.PcdSerialUseHardwareFlowControl ## CONSUMES
+ gEfiMdeModulePkgTokenSpaceGuid.PcdSerialDetectCable ## SOMETIMES_CONSUMES
+ gEfiMdeModulePkgTokenSpaceGuid.PcdSerialRegisterBase ## CONSUMES
+ gEfiMdeModulePkgTokenSpaceGuid.PcdSerialBaudRate ## CONSUMES
+ gEfiMdeModulePkgTokenSpaceGuid.PcdSerialLineControl ## CONSUMES
+ gEfiMdeModulePkgTokenSpaceGuid.PcdSerialFifoControl ## CONSUMES
+ gEfiMdeModulePkgTokenSpaceGuid.PcdSerialClockRate ## CONSUMES
+ gEfiMdeModulePkgTokenSpaceGuid.PcdSerialPciDeviceInfo ## CONSUMES
+ gEfiMdeModulePkgTokenSpaceGuid.PcdSerialExtendedTxFifoSize ## CONSUMES
+ gEfiMdeModulePkgTokenSpaceGuid.PcdSerialRegisterStride ## CONSUMES
+ gUefiOvmfPkgTokenSpaceGuid.PcdDeviceTreeInitialBaseAddress ## CONSUMES