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/** @file
UART Serial Port library functions
Copyright (c) 2006 - 2009, Intel Corporation
All rights reserved. This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution. The full text of the license may be found at
http://opensource.org/licenses/bsd-license.php
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
**/
#include <Base.h>
#include <Library/IoLib.h>
#include <Library/SerialPortLib.h>
//---------------------------------------------
// UART Register Offsets
//---------------------------------------------
#define BAUD_LOW_OFFSET 0x00
#define BAUD_HIGH_OFFSET 0x01
#define IER_OFFSET 0x01
#define LCR_SHADOW_OFFSET 0x01
#define FCR_SHADOW_OFFSET 0x02
#define IR_CONTROL_OFFSET 0x02
#define FCR_OFFSET 0x02
#define EIR_OFFSET 0x02
#define BSR_OFFSET 0x03
#define LCR_OFFSET 0x03
#define MCR_OFFSET 0x04
#define LSR_OFFSET 0x05
#define MSR_OFFSET 0x06
//---------------------------------------------
// UART Register Bit Defines
//---------------------------------------------
#define LSR_TXRDY 0x20
#define LSR_RXDA 0x01
#define DLAB 0x01
//---------------------------------------------
// UART Settings
//---------------------------------------------
UINT16 gUartBase = 0x3F8;
UINTN gBps = 115200;
UINT8 gData = 8;
UINT8 gStop = 1;
UINT8 gParity = 0;
UINT8 gBreakSet = 0;
/**
Initialize the serial device hardware.
If no initialization is required, then return RETURN_SUCCESS.
If the serial device was successfuly 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 serail device could not be initialized.
**/
RETURN_STATUS
EFIAPI
SerialPortInitialize (
VOID
)
{
UINTN Divisor;
UINT8 OutputData;
UINT8 Data;
//
// Map 5..8 to 0..3
//
Data = (UINT8) (gData - (UINT8) 5);
//
// Calculate divisor for baud generator
//
Divisor = 115200 / gBps;
//
// Set communications format
//
OutputData = (UINT8) ((DLAB << 7) | (gBreakSet << 6) | (gParity << 3) | (gStop << 2) | Data);
IoWrite8 ((UINTN) (gUartBase + LCR_OFFSET), OutputData);
//
// Configure baud rate
//
IoWrite8 ((UINTN) (gUartBase + BAUD_HIGH_OFFSET), (UINT8) (Divisor >> 8));
IoWrite8 ((UINTN) (gUartBase + BAUD_LOW_OFFSET), (UINT8) (Divisor & 0xff));
//
// Switch back to bank 0
//
OutputData = (UINT8) ((~DLAB << 7) | (gBreakSet << 6) | (gParity << 3) | (gStop << 2) | Data);
IoWrite8 ((UINTN) (gUartBase + LCR_OFFSET), OutputData);
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 read operation failed.
**/
UINTN
EFIAPI
SerialPortWrite (
IN UINT8 *Buffer,
IN UINTN NumberOfBytes
)
{
UINTN Result;
UINT8 Data;
if (Buffer == NULL) {
return 0;
}
Result = NumberOfBytes;
while (NumberOfBytes--) {
//
// Wait for the serail port to be ready.
//
do {
Data = IoRead8 ((UINT16) gUartBase + LSR_OFFSET);
} while ((Data & LSR_TXRDY) == 0);
IoWrite8 ((UINT16) gUartBase, *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 Result;
UINT8 Data;
if (NULL == Buffer) {
return 0;
}
Result = NumberOfBytes;
while (NumberOfBytes--) {
//
// Wait for the serail port to be ready.
//
do {
Data = IoRead8 ((UINT16) gUartBase + LSR_OFFSET);
} while ((Data & LSR_RXDA) == 0);
*Buffer++ = IoRead8 ((UINT16) gUartBase);
}
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
)
{
UINT8 Data;
//
// Read the serial port status.
//
Data = IoRead8 ((UINT16) gUartBase + LSR_OFFSET);
return (BOOLEAN) ((Data & LSR_RXDA) != 0);
}
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