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/** @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>
Copyright (c) 2017, Advanced Micro Devices. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include <Library/BaseLib.h>
#include <Library/DebugLib.h>
#include <Library/QemuFwCfgLib.h>
#include "QemuFwCfgLibInternal.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 ((DEBUG_INFO, "FW CFG Signature: 0x%x\n", Signature));
QemuFwCfgSelectItem (QemuFwCfgItemInterfaceVersion);
Revision = QemuFwCfgRead32 ();
DEBUG ((DEBUG_INFO, "FW CFG Revision: 0x%x\n", Revision));
if ((Signature != SIGNATURE_32 ('Q', 'E', 'M', 'U')) ||
(Revision < 1)
) {
DEBUG ((DEBUG_INFO, "QemuFwCfg interface not supported.\n"));
return FALSE;
}
DEBUG ((DEBUG_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
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;
}
/**
Returns a boolean indicating whether QEMU provides the DMA-like access method
for fw_cfg.
@retval TRUE The DMA-like access method is available.
@retval FALSE The DMA-like access method is unavailable.
**/
BOOLEAN
InternalQemuFwCfgDmaIsAvailable (
VOID
)
{
return FALSE;
}
/**
Transfer an array of bytes, or skip a number of bytes, using the DMA
interface.
@param[in] Size Size in bytes to transfer or skip.
@param[in,out] Buffer Buffer to read data into or write data from. Ignored,
and may be NULL, if Size is zero, or Control is
FW_CFG_DMA_CTL_SKIP.
@param[in] Control One of the following:
FW_CFG_DMA_CTL_WRITE - write to fw_cfg from Buffer.
FW_CFG_DMA_CTL_READ - read from fw_cfg into Buffer.
FW_CFG_DMA_CTL_SKIP - skip bytes in fw_cfg.
**/
VOID
InternalQemuFwCfgDmaBytes (
IN UINT32 Size,
IN OUT VOID *Buffer OPTIONAL,
IN UINT32 Control
)
{
//
// We should never reach here
//
ASSERT (FALSE);
CpuDeadLoop ();
}
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