/** @file
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16550 and PL011 Serial Port library functions for Raspberry Pi
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Copyright (c) 2020, Pete Batard <pete@akeo.ie>
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Copyright (c) 2018, AMD Incorporated. All rights reserved.<BR>
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Copyright (c) 2014, Hewlett-Packard Development Company, L.P.<BR>
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Copyright (c) 2012 - 2016, ARM Ltd. All rights reserved.<BR>
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Copyright (c) 2008 - 2010, Apple Inc. All rights reserved.<BR>
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Copyright (c) 2006 - 2019, Intel Corporation. All rights reserved.<BR>
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SPDX-License-Identifier: BSD-2-Clause-Patent
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**/
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#include <Base.h>
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#include <Library/IoLib.h>
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#include <Library/PcdLib.h>
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#include <Library/PL011UartLib.h>
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#include <Library/SerialPortLib.h>
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#include "DualSerialPortLib.h"
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BOOLEAN UsePl011Uart = FALSE;
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BOOLEAN UsePl011UartSet = FALSE;
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/**
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Read an 8-bit 16550 register.
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@param Base The base address register of UART device.
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@param Offset The offset of the 16550 register to read.
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@return The value read from the 16550 register.
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**/
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UINT8
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SerialPortReadRegister (
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UINTN Base,
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UINTN Offset
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)
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{
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return MmioRead8 (Base + Offset * PcdGet32 (PcdSerialRegisterStride));
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}
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/**
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Write an 8-bit 16550 register.
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@param Base The base address register of UART device.
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@param Offset The offset of the 16550 register to write.
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@param Value The value to write to the 16550 register specified by Offset.
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@return The value written to the 16550 register.
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**/
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UINT8
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SerialPortWriteRegister (
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UINTN Base,
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UINTN Offset,
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UINT8 Value
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)
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{
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return MmioWrite8 (Base + Offset * PcdGet32 (PcdSerialRegisterStride), Value);
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}
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/**
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Return whether the hardware flow control signal allows writing.
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@param SerialRegisterBase The base address register of UART device.
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@retval TRUE The serial port is writable.
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@retval FALSE The serial port is not writable.
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**/
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STATIC
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BOOLEAN
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SerialPortWritable (
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UINTN SerialRegisterBase
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)
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{
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if (PcdGetBool (PcdSerialUseHardwareFlowControl)) {
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if (PcdGetBool (PcdSerialDetectCable)) {
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//
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// Wait for both DSR and CTS to be set
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// DSR is set if a cable is connected.
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// CTS is set if it is ok to transmit data
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//
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// DSR CTS Description Action
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// === === ======================================== ========
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// 0 0 No cable connected. Wait
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// 0 1 No cable connected. Wait
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// 1 0 Cable connected, but not clear to send. Wait
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// 1 1 Cable connected, and clear to send. Transmit
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//
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return (BOOLEAN) ((SerialPortReadRegister (SerialRegisterBase, R_UART_MSR) & (B_UART_MSR_DSR | B_UART_MSR_CTS)) == (B_UART_MSR_DSR | B_UART_MSR_CTS));
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} else {
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//
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// Wait for both DSR and CTS to be set OR for DSR to be clear.
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// DSR is set if a cable is connected.
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// CTS is set if it is ok to transmit data
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//
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// DSR CTS Description Action
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// === === ======================================== ========
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// 0 0 No cable connected. Transmit
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// 0 1 No cable connected. Transmit
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// 1 0 Cable connected, but not clear to send. Wait
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// 1 1 Cable connected, and clar to send. Transmit
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//
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return (BOOLEAN) ((SerialPortReadRegister (SerialRegisterBase, R_UART_MSR) & (B_UART_MSR_DSR | B_UART_MSR_CTS)) != (B_UART_MSR_DSR));
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}
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}
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return TRUE;
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}
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/**
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Write data from buffer to serial device.
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Writes NumberOfBytes data bytes from Buffer to the serial device.
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The number of bytes actually written to the serial device is returned.
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If the return value is less than NumberOfBytes, then the write operation failed.
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If Buffer is NULL, then ASSERT().
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If NumberOfBytes is zero, then return 0.
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@param Buffer Pointer to the data buffer to be written.
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@param NumberOfBytes Number of bytes to written to the serial device.
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@retval 0 NumberOfBytes is 0.
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@retval >0 The number of bytes written to the serial device.
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If this value is less than NumberOfBytes, then the write operation failed.
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**/
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UINTN
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EFIAPI
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SerialPortWrite (
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IN UINT8 *Buffer,
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IN UINTN NumberOfBytes
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)
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{
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UINTN SerialRegisterBase;
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UINTN Result;
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UINTN Index;
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UINTN FifoSize;
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//
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// Serial writes may happen *before* the UART has been initialized
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// and if we use the wrong UART then, all kind of bad things happen.
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// To alleviate this, we add UART detection in SerialPortWrite and
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// guard the UART detection with a second boolean.
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//
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if (!UsePl011UartSet) {
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UsePl011Uart = ((MmioRead32(GPIO_BASE_ADDRESS + 4) & 0x0003F000) == 0x00024000);
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UsePl011UartSet = TRUE;
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}
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if (UsePl011Uart) {
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return PL011UartWrite (PL011_UART_REGISTER_BASE, Buffer, NumberOfBytes);
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} else {
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if (Buffer == NULL) {
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return 0;
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}
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SerialRegisterBase = MINI_UART_REGISTER_BASE;
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if (NumberOfBytes == 0) {
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//
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// Flush the hardware
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//
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//
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// Wait for both the transmit FIFO and shift register empty.
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//
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while ((SerialPortReadRegister (SerialRegisterBase, R_UART_LSR) & (B_UART_LSR_TEMT | B_UART_LSR_TXRDY)) != (B_UART_LSR_TEMT | B_UART_LSR_TXRDY));
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//
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// Wait for the hardware flow control signal
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//
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while (!SerialPortWritable (SerialRegisterBase));
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return 0;
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}
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//
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// Compute the maximum size of the Tx FIFO
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//
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FifoSize = 1;
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if ((PcdGet8 (PcdSerialFifoControl) & B_UART_FCR_FIFOE) != 0) {
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if ((PcdGet8 (PcdSerialFifoControl) & B_UART_FCR_FIFO64) == 0) {
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FifoSize = 16;
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} else {
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FifoSize = PcdGet32 (PcdSerialExtendedTxFifoSize);
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}
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}
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Result = NumberOfBytes;
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while (NumberOfBytes != 0) {
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//
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// Wait for the serial port to be ready, to make sure both the transmit FIFO
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// and shift register empty.
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//
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while ((SerialPortReadRegister (SerialRegisterBase, R_UART_LSR) & (B_UART_LSR_TEMT | B_UART_LSR_TXRDY)) != (B_UART_LSR_TEMT | B_UART_LSR_TXRDY));
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//
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// Fill then entire Tx FIFO
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//
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for (Index = 0; Index < FifoSize && NumberOfBytes != 0; Index++, NumberOfBytes--, Buffer++) {
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//
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// Wait for the hardware flow control signal
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//
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while (!SerialPortWritable (SerialRegisterBase));
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//
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// Write byte to the transmit buffer.
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//
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SerialPortWriteRegister (SerialRegisterBase, R_UART_TXBUF, *Buffer);
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}
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}
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return Result;
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}
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}
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