ArmVirtPkg: introduce DebugLibFdtPL011Uart RAM instance

Introduce three new DebugLib instances, forked from
MdePkg/Library/BaseDebugLibSerialPort. All three instances rely on
PL011UartLib rather than SerialPortLib so that they can customize the
PL011 UART that the debug messages are written to. All three instances
direct the debug output to the first such PL011 UART that *differs* from
the one specified in the Device Tree's /chosen node's "stdout-path"
property.

From these, DebugLibFdtPL011UartRam mirrors FdtPL011SerialPortLib: it
relies on the EarlyPL011BaseAddress GUID HOB, and initializes the UART --
a UART different from FdtPL011SerialPortLib's -- only once in the lifetime
of the containing module. Suitable for module types that can only execute
from RAM (i.e., all types different from SEC, PEI_CORE, PEIM), except
DXE_RUNTIME_DRIVER.

(Note that OVMF uses a similar set of dedicated DebugLib instances
(PlatformDebugLibIoPort) for logging to the (x86-only) isa-debugcon device
from various firmware phases.)

The contexts in which these DebugLib instances run are identical to those
in which the corresponding SerialPortLib instances run. The particular
original dependency chain is

  BaseDebugLibSerialPort (not SEC, PEI_CORE, PEIM, DXE_RUNTIME_DRIVER)
    FdtPL011SerialPortLib
      gEarlyPL011BaseAddressGuid
      HobLib
      PL011UartLib

and the new dependency chain is

  DebugLibFdtPL011UartRam (not SEC, PEI_CORE, PEIM, DXE_RUNTIME_DRIVER)
    gEarlyPL011BaseAddressGuid
    HobLib
    PL011UartLib

Note that FdtPL011SerialPortLib remains in use (just not via
BaseDebugLibSerialPort); for instance by MdeModulePkg/Universal/SerialDxe,
which produces the SerialIo protocol, underlying the UEFI console.

The ArmVirtPkg DSC files will be switched to the new library instances in
a separate patch.

This patch is worth viewing with "git show --find-copies-harder".

Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Leif Lindholm <quic_llindhol@quicinc.com>
Cc: Sami Mujawar <sami.mujawar@arm.com>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20231008153912.175941-8-lersek@redhat.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=4577
[lersek@redhat.com: add TianoCore BZ reference]

ArmVirtPkg/Library/DebugLibFdtPL011Uart/DebugLibFdtPL011UartRam.inf

@@ -0,0 +1,60 @@
+## @file
+# DebugLib instance that produces debug output directly via PL011UartLib.
+#
+# If there are at least two PL011 UARTs in the device tree, and the /chosen
+# node's "stdout-path" property references one PL011 UART, then both raw
+# SerialPortLib IO, and -- via SerialDxe -- UEFI console IO, will occur on that
+# UART; and this DebugLib instance will produce output on a *different* UART.
+#
+# This instance is suitable for modules that can only run from RAM (except
+# DXE_RUNTIME_DRIVER).
+#
+# Copyright (C) Red Hat
+#
+# SPDX-License-Identifier: BSD-2-Clause-Patent
+##
+
+[Defines]
+  INF_VERSION    = 1.27
+  BASE_NAME      = DebugLibFdtPL011UartRam
+  FILE_GUID      = 0584DE55-9C4C-49C1-ADA0-F62C9C1F3600
+  MODULE_TYPE    = BASE
+  VERSION_STRING = 1.0
+  LIBRARY_CLASS  = DebugLib|DXE_CORE SMM_CORE MM_CORE_STANDALONE DXE_DRIVER DXE_SMM_DRIVER SMM_DRIVER MM_STANDALONE UEFI_DRIVER UEFI_APPLICATION
+  CONSTRUCTOR    = DebugLibFdtPL011UartRamConstructor
+
+[Sources]
+  DebugLib.c
+  Ram.c
+  Ram.h
+  RamNonRuntime.c
+  Write.h
+
+[Packages]
+  ArmPlatformPkg/ArmPlatformPkg.dec
+  ArmVirtPkg/ArmVirtPkg.dec
+  MdePkg/MdePkg.dec
+
+[LibraryClasses]
+  BaseLib
+  BaseMemoryLib
+  DebugPrintErrorLevelLib
+  HobLib                  # Ram.c
+  PL011UartLib
+  PcdLib
+  PrintLib
+
+[Pcd]
+  gEfiMdePkgTokenSpaceGuid.PcdDebugClearMemoryValue
+  gEfiMdePkgTokenSpaceGuid.PcdDebugPropertyMask
+  gEfiMdePkgTokenSpaceGuid.PcdFixedDebugPrintErrorLevel
+
+[FixedPcd]
+  gArmPlatformTokenSpaceGuid.PL011UartClkInHz
+  gEfiMdePkgTokenSpaceGuid.PcdUartDefaultBaudRate
+  gEfiMdePkgTokenSpaceGuid.PcdUartDefaultDataBits
+  gEfiMdePkgTokenSpaceGuid.PcdUartDefaultParity
+  gEfiMdePkgTokenSpaceGuid.PcdUartDefaultStopBits
+
+[Guids]
+  gEarlyPL011BaseAddressGuid # Ram.c

ArmVirtPkg/Library/DebugLibFdtPL011Uart/Ram.c

@@ -0,0 +1,124 @@
+/** @file
+  Define DebugLibFdtPL011UartWrite() for modules that can only run from RAM.
+
+  Copyright (C) Red Hat
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+#include <Uefi/UefiBaseType.h>
+#include <Uefi/UefiMultiPhase.h>
+#include <Pi/PiBootMode.h>
+#include <Pi/PiHob.h>
+#include <Library/HobLib.h>
+#include <Library/PL011UartLib.h>
+#include <Library/PcdLib.h>
+#include <Guid/EarlyPL011BaseAddress.h>
+
+#include "Ram.h"
+#include "Write.h"
+
+UINTN          mDebugLibFdtPL011UartAddress;
+RETURN_STATUS  mDebugLibFdtPL011UartPermanentStatus = RETURN_SUCCESS;
+
+/**
+  Statefully initialize both the library instance and the debug PL011 UART.
+**/
+STATIC
+RETURN_STATUS
+Initialize (
+  VOID
+  )
+{
+  CONST VOID                      *Hob;
+  CONST EARLY_PL011_BASE_ADDRESS  *UartBase;
+  RETURN_STATUS                   Status;
+  UINTN                           DebugAddress;
+  UINT64                          BaudRate;
+  UINT32                          ReceiveFifoDepth;
+  EFI_PARITY_TYPE                 Parity;
+  UINT8                           DataBits;
+  EFI_STOP_BITS_TYPE              StopBits;
+
+  if (mDebugLibFdtPL011UartAddress != 0) {
+    return RETURN_SUCCESS;
+  }
+
+  if (RETURN_ERROR (mDebugLibFdtPL011UartPermanentStatus)) {
+    return mDebugLibFdtPL011UartPermanentStatus;
+  }
+
+  Hob = GetFirstGuidHob (&gEarlyPL011BaseAddressGuid);
+  if ((Hob == NULL) || (GET_GUID_HOB_DATA_SIZE (Hob) != sizeof *UartBase)) {
+    Status = RETURN_NOT_FOUND;
+    goto Failed;
+  }
+
+  UartBase = GET_GUID_HOB_DATA (Hob);
+
+  DebugAddress = (UINTN)UartBase->DebugAddress;
+  if (DebugAddress == 0) {
+    Status = RETURN_NOT_FOUND;
+    goto Failed;
+  }
+
+  BaudRate         = (UINTN)PcdGet64 (PcdUartDefaultBaudRate);
+  ReceiveFifoDepth = 0; // Use the default value for Fifo depth
+  Parity           = (EFI_PARITY_TYPE)PcdGet8 (PcdUartDefaultParity);
+  DataBits         = PcdGet8 (PcdUartDefaultDataBits);
+  StopBits         = (EFI_STOP_BITS_TYPE)PcdGet8 (PcdUartDefaultStopBits);
+
+  Status = PL011UartInitializePort (
+             DebugAddress,
+             FixedPcdGet32 (PL011UartClkInHz),
+             &BaudRate,
+             &ReceiveFifoDepth,
+             &Parity,
+             &DataBits,
+             &StopBits
+             );
+  if (RETURN_ERROR (Status)) {
+    goto Failed;
+  }
+
+  mDebugLibFdtPL011UartAddress = DebugAddress;
+  return RETURN_SUCCESS;
+
+Failed:
+  mDebugLibFdtPL011UartPermanentStatus = Status;
+  return Status;
+}
+
+/**
+  (Copied from SerialPortWrite() in "MdePkg/Include/Library/SerialPortLib.h" at
+  commit c4547aefb3d0, with the Buffer non-nullity assertion removed:)
+
+  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 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
+DebugLibFdtPL011UartWrite (
+  IN UINT8  *Buffer,
+  IN UINTN  NumberOfBytes
+  )
+{
+  RETURN_STATUS  Status;
+
+  Status = Initialize ();
+  if (RETURN_ERROR (Status)) {
+    return 0;
+  }
+
+  return PL011UartWrite (mDebugLibFdtPL011UartAddress, Buffer, NumberOfBytes);
+}

ArmVirtPkg/Library/DebugLibFdtPL011Uart/Ram.h

@@ -0,0 +1,18 @@
+/** @file
+  Declare the variables that modules that can only run from RAM use for
+  remembering initialization status.
+
+  Copyright (C) Red Hat
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+#ifndef DEBUG_LIB_FDT_PL011_UART_RAM_H_
+#define DEBUG_LIB_FDT_PL011_UART_RAM_H_
+
+#include <Base.h>
+
+extern UINTN          mDebugLibFdtPL011UartAddress;
+extern RETURN_STATUS  mDebugLibFdtPL011UartPermanentStatus;
+
+#endif

ArmVirtPkg/Library/DebugLibFdtPL011Uart/RamNonRuntime.c

@@ -0,0 +1,27 @@
+/** @file
+  Provide an empty lib instance constructor for modules that can only run from
+  RAM but are not DXE_RUNTIME_DRIVER modules.
+
+  This ensures that e.g. any HobLib constructor is ordered correctly. (The
+  DXE_CORE calls constructors late, but the DXE_CORE HobLib instance needs no
+  construction anyway.)
+
+  Copyright (C) Red Hat
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+#include <Base.h>
+
+/**
+  Empty library instance constructor, only for ensuring the connectivity of the
+  constructor dependency graph.
+**/
+RETURN_STATUS
+EFIAPI
+DebugLibFdtPL011UartRamConstructor (
+  VOID
+  )
+{
+  return RETURN_SUCCESS;
+}