2c8dcbc65a
The benefits of the DMA-like access method are (a) speed, (b) write support in QEMU 2.9+. (IOPort-based write support was discontinued in QEMU 2.4, and the DMA-based one is being added to QEMU 2.9. Write support needs no separate feature detection because writeability is governed on the level of individual fw_cfg files -- if a file meant to be written by the firmware exists in the directory, then it is writeable with the DMA method.) We don't enable this feature for the SEC library instance, because: - the SEC instance remains without clients (I've checked that it builds though), - in SEC, any possible fw_cfg use is expected to be small and read-only. Cc: Jordan Justen <jordan.l.justen@intel.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
117 lines
3.0 KiB
C
117 lines
3.0 KiB
C
/** @file
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Stateful and implicitly initialized fw_cfg library implementation.
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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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#include "QemuFwCfgLibInternal.h"
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STATIC BOOLEAN mQemuFwCfgSupported = FALSE;
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STATIC BOOLEAN mQemuFwCfgDmaSupported;
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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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return InternalQemuFwCfgIsAvailable ();
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}
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RETURN_STATUS
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EFIAPI
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QemuFwCfgInitialize (
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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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//
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// Enable the access routines while probing to see if it is supported.
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// For probing we always use the IO Port (IoReadFifo8()) access method.
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//
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mQemuFwCfgSupported = TRUE;
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mQemuFwCfgDmaSupported = FALSE;
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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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mQemuFwCfgSupported = FALSE;
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return RETURN_SUCCESS;
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}
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if ((Revision & FW_CFG_F_DMA) == 0) {
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DEBUG ((DEBUG_INFO, "QemuFwCfg interface (IO Port) is supported.\n"));
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} else {
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mQemuFwCfgDmaSupported = TRUE;
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DEBUG ((DEBUG_INFO, "QemuFwCfg interface (DMA) is supported.\n"));
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}
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return RETURN_SUCCESS;
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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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InternalQemuFwCfgIsAvailable (
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VOID
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)
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{
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return mQemuFwCfgSupported;
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}
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/**
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Returns a boolean indicating whether QEMU provides the DMA-like access method
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for fw_cfg.
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@retval TRUE The DMA-like access method is available.
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@retval FALSE The DMA-like access method is unavailable.
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**/
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BOOLEAN
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InternalQemuFwCfgDmaIsAvailable (
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VOID
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)
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{
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return mQemuFwCfgDmaSupported;
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}
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