mirror of https://github.com/acidanthera/audk.git
82 lines
2.2 KiB
C
82 lines
2.2 KiB
C
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/** @file
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Stateless fw_cfg library implementation.
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Clients must call QemuFwCfgIsAvailable() first.
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Copyright (C) 2013, Red Hat, Inc.
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Copyright (c) 2011 - 2013, Intel Corporation. All rights reserved.<BR>
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This program and the accompanying materials are licensed and made available
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under the terms and conditions of the BSD License which accompanies this
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distribution. The full text of the license may be found at
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http://opensource.org/licenses/bsd-license.php
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THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT
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WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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**/
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#include <Library/DebugLib.h>
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#include <Library/QemuFwCfgLib.h>
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/**
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Returns a boolean indicating if the firmware configuration interface
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is available or not.
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This function may change fw_cfg state.
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@retval TRUE The interface is available
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@retval FALSE The interface is not available
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**/
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BOOLEAN
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EFIAPI
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QemuFwCfgIsAvailable (
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VOID
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)
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{
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UINT32 Signature;
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UINT32 Revision;
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QemuFwCfgSelectItem (QemuFwCfgItemSignature);
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Signature = QemuFwCfgRead32 ();
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DEBUG ((EFI_D_INFO, "FW CFG Signature: 0x%x\n", Signature));
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QemuFwCfgSelectItem (QemuFwCfgItemInterfaceVersion);
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Revision = QemuFwCfgRead32 ();
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DEBUG ((EFI_D_INFO, "FW CFG Revision: 0x%x\n", Revision));
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if ((Signature != SIGNATURE_32 ('Q', 'E', 'M', 'U')) ||
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(Revision < 1)
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) {
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DEBUG ((EFI_D_INFO, "QemuFwCfg interface not supported.\n"));
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return FALSE;
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}
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DEBUG ((EFI_D_INFO, "QemuFwCfg interface is supported.\n"));
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return TRUE;
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}
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/**
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Returns a boolean indicating if the firmware configuration interface is
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available for library-internal purposes.
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This function never changes fw_cfg state.
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@retval TRUE The interface is available internally.
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@retval FALSE The interface is not available internally.
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**/
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BOOLEAN
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EFIAPI
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InternalQemuFwCfgIsAvailable (
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VOID
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)
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{
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//
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// We always return TRUE, because the consumer of this library ought to have
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// called QemuFwCfgIsAvailable before making other calls which would hit this
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// path.
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//
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return TRUE;
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}
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