OvmfPkg: QemuFwCfgLib: implement for SEC

The QemuFwCfgSecLib library instance
- is stateless,
- has no library constructor,
- is available to SEC client code,
- must be queried with QemuFwCfgIsAvailable() before use,
- is restricted to SEC in order to limit the explicit querying
  requirement. (There is no current user.)

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15046 6f19259b-4bc3-4df7-8a09-765794883524

OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgSec.c

@@ -0,0 +1,81 @@
+/** @file
+
+  Stateless fw_cfg library implementation.
+
+  Clients must call QemuFwCfgIsAvailable() first.
+
+  Copyright (C) 2013, Red Hat, Inc.
+  Copyright (c) 2011 - 2013, Intel Corporation. All rights reserved.<BR>
+
+  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 <Library/DebugLib.h>
+#include <Library/QemuFwCfgLib.h>
+
+
+/**
+  Returns a boolean indicating if the firmware configuration interface
+  is available or not.
+
+  This function may change fw_cfg state.
+
+  @retval    TRUE   The interface is available
+  @retval    FALSE  The interface is not available
+
+**/
+BOOLEAN
+EFIAPI
+QemuFwCfgIsAvailable (
+  VOID
+  )
+{
+  UINT32 Signature;
+  UINT32 Revision;
+
+  QemuFwCfgSelectItem (QemuFwCfgItemSignature);
+  Signature = QemuFwCfgRead32 ();
+  DEBUG ((EFI_D_INFO, "FW CFG Signature: 0x%x\n", Signature));
+  QemuFwCfgSelectItem (QemuFwCfgItemInterfaceVersion);
+  Revision = QemuFwCfgRead32 ();
+  DEBUG ((EFI_D_INFO, "FW CFG Revision: 0x%x\n", Revision));
+  if ((Signature != SIGNATURE_32 ('Q', 'E', 'M', 'U')) ||
+      (Revision < 1)
+     ) {
+    DEBUG ((EFI_D_INFO, "QemuFwCfg interface not supported.\n"));
+    return FALSE;
+  }
+
+  DEBUG ((EFI_D_INFO, "QemuFwCfg interface is supported.\n"));
+  return TRUE;
+}
+
+
+/**
+  Returns a boolean indicating if the firmware configuration interface is
+  available for library-internal purposes.
+
+  This function never changes fw_cfg state.
+
+  @retval    TRUE   The interface is available internally.
+  @retval    FALSE  The interface is not available internally.
+**/
+BOOLEAN
+EFIAPI
+InternalQemuFwCfgIsAvailable (
+  VOID
+  )
+{
+  //
+  // We always return TRUE, because the consumer of this library ought to have
+  // called QemuFwCfgIsAvailable before making other calls which would hit this
+  // path.
+  //
+  return TRUE;
+}

OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgSecLib.inf

@@ -0,0 +1,54 @@
+## @file
+#
+#  Stateless fw_cfg library that must be queried before use.
+#
+#  Copyright (C) 2013, Red Hat, Inc.
+#  Copyright (c) 2008 - 2012, Intel Corporation. All rights reserved.<BR>
+#
+#  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                    = 0x00010005
+  BASE_NAME                      = QemuFwCfgSecLib
+  FILE_GUID                      = 60a910e5-7443-413d-9a30-97e57497cd1b
+  MODULE_TYPE                    = BASE
+  VERSION_STRING                 = 1.0
+  LIBRARY_CLASS                  = QemuFwCfgLib|SEC
+
+#
+# The following information is for reference only and not required by the build tools.
+#
+#  VALID_ARCHITECTURES           = IA32 X64
+#
+
+[Sources]
+  QemuFwCfgLib.c
+  QemuFwCfgSec.c
+
+[Sources.IA32]
+  Ia32/IoLibExAsm.asm
+  Ia32/IoLibExAsm.S
+
+[Sources.X64]
+  X64/IoLibExAsm.asm
+  X64/IoLibExAsm.S
+
+[Packages]
+  MdePkg/MdePkg.dec
+  OvmfPkg/OvmfPkg.dec
+
+[LibraryClasses]
+  BaseLib
+  BaseMemoryLib
+  DebugLib
+  IoLib
+  MemoryAllocationLib
+

OvmfPkg/OvmfPkgIa32.dsc

@@ -127,6 +127,7 @@
 !endif
 
 [LibraryClasses.common.SEC]
+  QemuFwCfgLib|OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgSecLib.inf
 !ifdef $(DEBUG_ON_SERIAL_PORT)
   DebugLib|MdePkg/Library/BaseDebugLibSerialPort/BaseDebugLibSerialPort.inf
 !else

OvmfPkg/OvmfPkgIa32X64.dsc

@@ -132,6 +132,7 @@
 !endif
 
 [LibraryClasses.common.SEC]
+  QemuFwCfgLib|OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgSecLib.inf
 !ifdef $(DEBUG_ON_SERIAL_PORT)
   DebugLib|MdePkg/Library/BaseDebugLibSerialPort/BaseDebugLibSerialPort.inf
 !else

OvmfPkg/OvmfPkgX64.dsc

@@ -132,6 +132,7 @@
 !endif
 
 [LibraryClasses.common.SEC]
+  QemuFwCfgLib|OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgSecLib.inf
 !ifdef $(DEBUG_ON_SERIAL_PORT)
   DebugLib|MdePkg/Library/BaseDebugLibSerialPort/BaseDebugLibSerialPort.inf
 !else