[PATCH v4 05/12] EmbeddedPkg: introduce PlatformHasAcpiLib

[Laszlo Ersek <lersek@redhat.com>]

Add the shorter-term library instance outlined in the previous patch to
EmbeddedPkg, so that we can imbue AcpiTableDxe with a protocol dependency
on EDKII_PLATFORM_HAS_ACPI_GUID.

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---

Notes:
    v4:
    - move to EmbeddedPkg [Ard, Laszlo]
    - refresh commit message
    - redirect INF / LibraryClasses to EmbeddedPkg.dec
    - pick up Ard's R-b
    
    v3:
    - move GUID to MdeModulePkg (see previous patch) [Leif, Ard]
    - replace ArmPkg.dec package dependency with MdeModulePkg.dec in INF
      file
    - rename gEdkiiPlatformHasAcpiProtocolGuid to gEdkiiPlatformHasAcpiGuid
      [Star]
    - update comment in empty constructor function accordingly

 EmbeddedPkg/Library/PlatformHasAcpiLib/PlatformHasAcpiLib.inf | 40 ++++++++++++++++++++
 EmbeddedPkg/Library/PlatformHasAcpiLib/PlatformHasAcpiLib.c   | 36 ++++++++++++++++++
 2 files changed, 76 insertions(+)

diff --git a/EmbeddedPkg/Library/PlatformHasAcpiLib/PlatformHasAcpiLib.inf b/EmbeddedPkg/Library/PlatformHasAcpiLib/PlatformHasAcpiLib.inf
new file mode 100644
index 000000000000..6268293ca97b
--- /dev/null
+++ b/EmbeddedPkg/Library/PlatformHasAcpiLib/PlatformHasAcpiLib.inf
@@ -0,0 +1,40 @@
+## @file
+# A hook-in library for MdeModulePkg/Universal/Acpi/AcpiTableDxe.
+#
+# Plugging this library instance into AcpiTableDxe makes
+# EFI_ACPI_TABLE_PROTOCOL and (if enabled) EFI_ACPI_SDT_PROTOCOL depend on the
+# platform's dynamic decision whether to expose an ACPI-based hardware
+# description to the operating system.
+#
+# Universal and platform specific DXE drivers that produce ACPI tables depend
+# on EFI_ACPI_TABLE_PROTOCOL / EFI_ACPI_SDT_PROTOCOL in turn.
+#
+# Copyright (C) 2017, Red Hat, Inc.
+#
+# 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.
+##
+
+[Defines]
+  INF_VERSION                    = 1.25
+  BASE_NAME                      = PlatformHasAcpiLib
+  FILE_GUID                      = 29beb028-0958-447b-be0a-12229235d77d
+  MODULE_TYPE                    = BASE
+  VERSION_STRING                 = 1.0
+  LIBRARY_CLASS                  = PlatformHasAcpiLib|DXE_DRIVER
+  CONSTRUCTOR                    = PlatformHasAcpiInitialize
+
+[Sources]
+  PlatformHasAcpiLib.c
+
+[Packages]
+  EmbeddedPkg/EmbeddedPkg.dec
+  MdePkg/MdePkg.dec
+
+[Depex]
+  gEdkiiPlatformHasAcpiGuid
diff --git a/EmbeddedPkg/Library/PlatformHasAcpiLib/PlatformHasAcpiLib.c b/EmbeddedPkg/Library/PlatformHasAcpiLib/PlatformHasAcpiLib.c
new file mode 100644
index 000000000000..2c73e71769eb
--- /dev/null
+++ b/EmbeddedPkg/Library/PlatformHasAcpiLib/PlatformHasAcpiLib.c
@@ -0,0 +1,36 @@
+/** @file
+  A hook-in library for MdeModulePkg/Universal/Acpi/AcpiTableDxe.
+
+  Plugging this library instance into AcpiTableDxe makes
+  EFI_ACPI_TABLE_PROTOCOL and (if enabled) EFI_ACPI_SDT_PROTOCOL depend on the
+  platform's dynamic decision whether to expose an ACPI-based hardware
+  description to the operating system.
+
+  Universal and platform specific DXE drivers that produce ACPI tables depend
+  on EFI_ACPI_TABLE_PROTOCOL / EFI_ACPI_SDT_PROTOCOL in turn.
+
+  Copyright (C) 2017, Red Hat, Inc.
+
+  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>
+
+RETURN_STATUS
+EFIAPI
+PlatformHasAcpiInitialize (
+  VOID
+  )
+{
+  //
+  // Do nothing, just imbue AcpiTableDxe with a protocol dependency on
+  // EDKII_PLATFORM_HAS_ACPI_GUID.
+  //
+  return RETURN_SUCCESS;
+}
-- 
2.9.3