Re: [edk2-devel] [PATCH v4 4/8] OvmfPkg: Add the QemuFwCfgMmioLib PEI stage version
Hi Ard,
Thanks,
Chao
On 2024/4/30 09:19, Chao Li wrote:
Hi Ard,
OK, I will submit the V5 today and make the adjustments according to
your suggestions.
On 2024/4/29 21:11, Ard Biesheuvel wrote:
On Fri, 26 Apr 2024 at 10:29, Chao Li wrote:
Added the PEI stage library for QemuFwCfgMmioLib, which uses the FDT to
find the fw_cfg and parse it.
BZ:https://bugzilla.tianocore.org/show_bug.cgi?id=4755
Cc: Ard Biesheuvel
Cc: Jiewen Yao
Cc: Gerd Hoffmann
Co-authored-by: Xianglai Li
Signed-off-by: Chao Li
---
.../Library/QemuFwCfgLib/QemuFwCfgMmioPei.c | 235 ++
.../QemuFwCfgLib/QemuFwCfgMmioPeiLib.inf | 52
2 files changed, 287 insertions(+)
create mode 100644 OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgMmioPei.c
create mode 100644 OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgMmioPeiLib.inf
diff --git a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgMmioPei.c
b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgMmioPei.c
new file mode 100644
index 00..055148de8e
--- /dev/null
+++ b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgMmioPei.c
@@ -0,0 +1,235 @@
+/** @file
+
+ Stateful and implicitly initialized fw_cfg library implementation.
+
+ Copyright (C) 2013 - 2014, Red Hat, Inc.
+ Copyright (c) 2011 - 2013, Intel Corporation. All rights reserved.
+ (C) Copyright 2021 Hewlett Packard Enterprise Development LP
+ Copyright (c) 2024 Loongson Technology Corporation Limited. All rights
reserved.
+
+ SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+#include
+
+#include
+#include
+#include
+#include
+#include
+
+#include
+
+#include "QemuFwCfgLibMmioInternal.h"
+
+/**
+ To get firmware configure selector address.
+
+ @param VOID
+
+ @retval firmware configure selector address
+**/
+UINTN
+EFIAPI
+QemuGetFwCfgSelectorAddress (
+ VOID
+ )
+{
+ QEMU_FW_CFG_RESOURCE *FwCfgResource;
+
+ FwCfgResource = QemuGetFwCfgResourceHob ();
+ ASSERT (FwCfgResource != NULL);
+
+ return FwCfgResource->FwCfgSelectorAddress;
+}
+
+/**
+ To get firmware configure Data address.
+
+ @param VOID
+
+ @retval firmware configure data address
+**/
+UINTN
+EFIAPI
+QemuGetFwCfgDataAddress (
+ VOID
+ )
+{
+ QEMU_FW_CFG_RESOURCE *FwCfgResource;
+
+ FwCfgResource = QemuGetFwCfgResourceHob ();
+ ASSERT (FwCfgResource != NULL);
+
+ return FwCfgResource->FwCfgDataAddress;
+}
+
+/**
+ To get firmware DMA address.
+
+ @param VOID
+
+ @retval firmware DMA address
+**/
+UINTN
+EFIAPI
+QemuGetFwCfgDmaAddress (
+ VOID
+ )
+{
+ QEMU_FW_CFG_RESOURCE *FwCfgResource;
+
+ FwCfgResource = QemuGetFwCfgResourceHob ();
+ ASSERT (FwCfgResource != NULL);
+
+ return FwCfgResource->FwCfgDmaAddress;
+}
+
+RETURN_STATUS
+EFIAPI
+QemuFwCfgInitialize (
+ VOID
+ )
+{
+ VOID *DeviceTreeBase;
+ INT32 Node;
+ INT32 Prev;
+ CONST CHAR8 *Type;
+ INT32 Len;
+ CONST UINT64 *Reg;
+ UINT64FwCfgSelectorAddress;
+ UINT64FwCfgSelectorSize;
+ UINT64FwCfgDataAddress;
+ UINT64FwCfgDataSize;
+ UINT64FwCfgDmaAddress;
+ UINT64FwCfgDmaSize;
+ QEMU_FW_CFG_RESOURCE *FwCfgResource;
+ VOID *Buffer;
+
+ //
+ // Check whether the Qemu firmware configure resources HOB has been created,
+ // if so use the resources in the HOB.
+ //
+ FwCfgResource = QemuGetFwCfgResourceHob ();
+ if (FwCfgResource != NULL) {
+return RETURN_SUCCESS;
+ }
+
+ DeviceTreeBase = (VOID *)(UINTN)PcdGet64 (PcdDeviceTreeInitialBaseAddress);
+ ASSERT (DeviceTreeBase != NULL);
+ //
+ // Make sure we have a valid device tree blob
+ //
+ ASSERT (fdt_check_header (DeviceTreeBase) == 0);
+
+ //
+ // Create resouce memory
+ //
+ Buffer = AllocatePages(EFI_SIZE_TO_PAGES (sizeof (QEMU_FW_CFG_RESOURCE)));
+ ASSERT (Buffer != NULL);
+ ZeroMem (Buffer, sizeof (QEMU_FW_CFG_RESOURCE));
+
+ FwCfgResource = (QEMU_FW_CFG_RESOURCE *)Buffer;
+
You will need to respin after all, so please incorporate the fixes I
proposed on v4
+ for (Prev = 0; ; Prev = Node) {
+Node = fdt_next_node (DeviceTreeBase, Prev, NULL);
+if (Node < 0) {
+ break;
+}
+
+//
+// Check for memory node
+//
+Type = fdt_getprop (DeviceTreeBase, Node, "compatible", &Len);
+if ((Type) &&
and here
+(AsciiStrnCmp (Type, "qemu,fw-cfg-mmio", Len) == 0))
+{
+ //
+ // Get the 'reg' property of this node. For now, we will assume
+ // two 8 byte quantities for base and size, respectively.
+ //
+ Reg = fdt_getprop (DeviceTreeBase, Node, "reg", &Len);
+ if ((Reg != 0) && (Len == (2 * sizeof (UINT64 {
+FwCfgDataAddress = SwapBytes64 (Reg[0]);
+FwCfgDataSize= 8;
+FwCfgSelectorAddress = FwCfgDataAddress + FwCfgDataSize;
+FwCfgSelectorSize= 2;
+
+//
+// The following ASSERT()s express
+//
+// Address + Size - 1 <= MAX_UINTN
+//
+
Re: [edk2-devel] [PATCH v4 4/8] OvmfPkg: Add the QemuFwCfgMmioLib PEI stage version
Hi Ard,
OK, I will submit the V5 today and make the adjustments according to
your suggestions.
Thanks,
Chao
On 2024/4/29 21:11, Ard Biesheuvel wrote:
On Fri, 26 Apr 2024 at 10:29, Chao Li wrote:
Added the PEI stage library for QemuFwCfgMmioLib, which uses the FDT to
find the fw_cfg and parse it.
BZ:https://bugzilla.tianocore.org/show_bug.cgi?id=4755
Cc: Ard Biesheuvel
Cc: Jiewen Yao
Cc: Gerd Hoffmann
Co-authored-by: Xianglai Li
Signed-off-by: Chao Li
---
.../Library/QemuFwCfgLib/QemuFwCfgMmioPei.c | 235 ++
.../QemuFwCfgLib/QemuFwCfgMmioPeiLib.inf | 52
2 files changed, 287 insertions(+)
create mode 100644 OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgMmioPei.c
create mode 100644 OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgMmioPeiLib.inf
diff --git a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgMmioPei.c
b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgMmioPei.c
new file mode 100644
index 00..055148de8e
--- /dev/null
+++ b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgMmioPei.c
@@ -0,0 +1,235 @@
+/** @file
+
+ Stateful and implicitly initialized fw_cfg library implementation.
+
+ Copyright (C) 2013 - 2014, Red Hat, Inc.
+ Copyright (c) 2011 - 2013, Intel Corporation. All rights reserved.
+ (C) Copyright 2021 Hewlett Packard Enterprise Development LP
+ Copyright (c) 2024 Loongson Technology Corporation Limited. All rights
reserved.
+
+ SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+#include
+
+#include
+#include
+#include
+#include
+#include
+
+#include
+
+#include "QemuFwCfgLibMmioInternal.h"
+
+/**
+ To get firmware configure selector address.
+
+ @param VOID
+
+ @retval firmware configure selector address
+**/
+UINTN
+EFIAPI
+QemuGetFwCfgSelectorAddress (
+ VOID
+ )
+{
+ QEMU_FW_CFG_RESOURCE *FwCfgResource;
+
+ FwCfgResource = QemuGetFwCfgResourceHob ();
+ ASSERT (FwCfgResource != NULL);
+
+ return FwCfgResource->FwCfgSelectorAddress;
+}
+
+/**
+ To get firmware configure Data address.
+
+ @param VOID
+
+ @retval firmware configure data address
+**/
+UINTN
+EFIAPI
+QemuGetFwCfgDataAddress (
+ VOID
+ )
+{
+ QEMU_FW_CFG_RESOURCE *FwCfgResource;
+
+ FwCfgResource = QemuGetFwCfgResourceHob ();
+ ASSERT (FwCfgResource != NULL);
+
+ return FwCfgResource->FwCfgDataAddress;
+}
+
+/**
+ To get firmware DMA address.
+
+ @param VOID
+
+ @retval firmware DMA address
+**/
+UINTN
+EFIAPI
+QemuGetFwCfgDmaAddress (
+ VOID
+ )
+{
+ QEMU_FW_CFG_RESOURCE *FwCfgResource;
+
+ FwCfgResource = QemuGetFwCfgResourceHob ();
+ ASSERT (FwCfgResource != NULL);
+
+ return FwCfgResource->FwCfgDmaAddress;
+}
+
+RETURN_STATUS
+EFIAPI
+QemuFwCfgInitialize (
+ VOID
+ )
+{
+ VOID *DeviceTreeBase;
+ INT32 Node;
+ INT32 Prev;
+ CONST CHAR8 *Type;
+ INT32 Len;
+ CONST UINT64 *Reg;
+ UINT64FwCfgSelectorAddress;
+ UINT64FwCfgSelectorSize;
+ UINT64FwCfgDataAddress;
+ UINT64FwCfgDataSize;
+ UINT64FwCfgDmaAddress;
+ UINT64FwCfgDmaSize;
+ QEMU_FW_CFG_RESOURCE *FwCfgResource;
+ VOID *Buffer;
+
+ //
+ // Check whether the Qemu firmware configure resources HOB has been created,
+ // if so use the resources in the HOB.
+ //
+ FwCfgResource = QemuGetFwCfgResourceHob ();
+ if (FwCfgResource != NULL) {
+return RETURN_SUCCESS;
+ }
+
+ DeviceTreeBase = (VOID *)(UINTN)PcdGet64 (PcdDeviceTreeInitialBaseAddress);
+ ASSERT (DeviceTreeBase != NULL);
+ //
+ // Make sure we have a valid device tree blob
+ //
+ ASSERT (fdt_check_header (DeviceTreeBase) == 0);
+
+ //
+ // Create resouce memory
+ //
+ Buffer = AllocatePages(EFI_SIZE_TO_PAGES (sizeof (QEMU_FW_CFG_RESOURCE)));
+ ASSERT (Buffer != NULL);
+ ZeroMem (Buffer, sizeof (QEMU_FW_CFG_RESOURCE));
+
+ FwCfgResource = (QEMU_FW_CFG_RESOURCE *)Buffer;
+
You will need to respin after all, so please incorporate the fixes I
proposed on v4
+ for (Prev = 0; ; Prev = Node) {
+Node = fdt_next_node (DeviceTreeBase, Prev, NULL);
+if (Node < 0) {
+ break;
+}
+
+//
+// Check for memory node
+//
+Type = fdt_getprop (DeviceTreeBase, Node, "compatible", &Len);
+if ((Type) &&
and here
+(AsciiStrnCmp (Type, "qemu,fw-cfg-mmio", Len) == 0))
+{
+ //
+ // Get the 'reg' property of this node. For now, we will assume
+ // two 8 byte quantities for base and size, respectively.
+ //
+ Reg = fdt_getprop (DeviceTreeBase, Node, "reg", &Len);
+ if ((Reg != 0) && (Len == (2 * sizeof (UINT64 {
+FwCfgDataAddress = SwapBytes64 (Reg[0]);
+FwCfgDataSize= 8;
+FwCfgSelectorAddress = FwCfgDataAddress + FwCfgDataSize;
+FwCfgSelectorSize= 2;
+
+//
+// The following ASSERT()s express
+//
+// Address + Size - 1 <= MAX_UINTN
+//
+// for both registers, that is, that t
Re: [edk2-devel] [PATCH v4 4/8] OvmfPkg: Add the QemuFwCfgMmioLib PEI stage version
On Fri, 26 Apr 2024 at 10:29, Chao Li wrote:
>
> Added the PEI stage library for QemuFwCfgMmioLib, which uses the FDT to
> find the fw_cfg and parse it.
>
> BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=4755
>
> Cc: Ard Biesheuvel
> Cc: Jiewen Yao
> Cc: Gerd Hoffmann
> Co-authored-by: Xianglai Li
> Signed-off-by: Chao Li
> ---
> .../Library/QemuFwCfgLib/QemuFwCfgMmioPei.c | 235 ++
> .../QemuFwCfgLib/QemuFwCfgMmioPeiLib.inf | 52
> 2 files changed, 287 insertions(+)
> create mode 100644 OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgMmioPei.c
> create mode 100644 OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgMmioPeiLib.inf
>
> diff --git a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgMmioPei.c
> b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgMmioPei.c
> new file mode 100644
> index 00..055148de8e
> --- /dev/null
> +++ b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgMmioPei.c
> @@ -0,0 +1,235 @@
> +/** @file
> +
> + Stateful and implicitly initialized fw_cfg library implementation.
> +
> + Copyright (C) 2013 - 2014, Red Hat, Inc.
> + Copyright (c) 2011 - 2013, Intel Corporation. All rights reserved.
> + (C) Copyright 2021 Hewlett Packard Enterprise Development LP
> + Copyright (c) 2024 Loongson Technology Corporation Limited. All rights
> reserved.
> +
> + SPDX-License-Identifier: BSD-2-Clause-Patent
> +**/
> +
> +#include
> +
> +#include
> +#include
> +#include
> +#include
> +#include
> +
> +#include
> +
> +#include "QemuFwCfgLibMmioInternal.h"
> +
> +/**
> + To get firmware configure selector address.
> +
> + @param VOID
> +
> + @retval firmware configure selector address
> +**/
> +UINTN
> +EFIAPI
> +QemuGetFwCfgSelectorAddress (
> + VOID
> + )
> +{
> + QEMU_FW_CFG_RESOURCE *FwCfgResource;
> +
> + FwCfgResource = QemuGetFwCfgResourceHob ();
> + ASSERT (FwCfgResource != NULL);
> +
> + return FwCfgResource->FwCfgSelectorAddress;
> +}
> +
> +/**
> + To get firmware configure Data address.
> +
> + @param VOID
> +
> + @retval firmware configure data address
> +**/
> +UINTN
> +EFIAPI
> +QemuGetFwCfgDataAddress (
> + VOID
> + )
> +{
> + QEMU_FW_CFG_RESOURCE *FwCfgResource;
> +
> + FwCfgResource = QemuGetFwCfgResourceHob ();
> + ASSERT (FwCfgResource != NULL);
> +
> + return FwCfgResource->FwCfgDataAddress;
> +}
> +
> +/**
> + To get firmware DMA address.
> +
> + @param VOID
> +
> + @retval firmware DMA address
> +**/
> +UINTN
> +EFIAPI
> +QemuGetFwCfgDmaAddress (
> + VOID
> + )
> +{
> + QEMU_FW_CFG_RESOURCE *FwCfgResource;
> +
> + FwCfgResource = QemuGetFwCfgResourceHob ();
> + ASSERT (FwCfgResource != NULL);
> +
> + return FwCfgResource->FwCfgDmaAddress;
> +}
> +
> +RETURN_STATUS
> +EFIAPI
> +QemuFwCfgInitialize (
> + VOID
> + )
> +{
> + VOID *DeviceTreeBase;
> + INT32 Node;
> + INT32 Prev;
> + CONST CHAR8 *Type;
> + INT32 Len;
> + CONST UINT64 *Reg;
> + UINT64FwCfgSelectorAddress;
> + UINT64FwCfgSelectorSize;
> + UINT64FwCfgDataAddress;
> + UINT64FwCfgDataSize;
> + UINT64FwCfgDmaAddress;
> + UINT64FwCfgDmaSize;
> + QEMU_FW_CFG_RESOURCE *FwCfgResource;
> + VOID *Buffer;
> +
> + //
> + // Check whether the Qemu firmware configure resources HOB has been
> created,
> + // if so use the resources in the HOB.
> + //
> + FwCfgResource = QemuGetFwCfgResourceHob ();
> + if (FwCfgResource != NULL) {
> +return RETURN_SUCCESS;
> + }
> +
> + DeviceTreeBase = (VOID *)(UINTN)PcdGet64 (PcdDeviceTreeInitialBaseAddress);
> + ASSERT (DeviceTreeBase != NULL);
> + //
> + // Make sure we have a valid device tree blob
> + //
> + ASSERT (fdt_check_header (DeviceTreeBase) == 0);
> +
> + //
> + // Create resouce memory
> + //
> + Buffer = AllocatePages(EFI_SIZE_TO_PAGES (sizeof (QEMU_FW_CFG_RESOURCE)));
> + ASSERT (Buffer != NULL);
> + ZeroMem (Buffer, sizeof (QEMU_FW_CFG_RESOURCE));
> +
> + FwCfgResource = (QEMU_FW_CFG_RESOURCE *)Buffer;
> +
You will need to respin after all, so please incorporate the fixes I
proposed on v4
> + for (Prev = 0; ; Prev = Node) {
> +Node = fdt_next_node (DeviceTreeBase, Prev, NULL);
> +if (Node < 0) {
> + break;
> +}
> +
> +//
> +// Check for memory node
> +//
> +Type = fdt_getprop (DeviceTreeBase, Node, "compatible", &Len);
> +if ((Type) &&
and here
> +(AsciiStrnCmp (Type, "qemu,fw-cfg-mmio", Len) == 0))
> +{
> + //
> + // Get the 'reg' property of this node. For now, we will assume
> + // two 8 byte quantities for base and size, respectively.
> + //
> + Reg = fdt_getprop (DeviceTreeBase, Node, "reg", &Len);
> + if ((Reg != 0) && (Len == (2 * sizeof (UINT64 {
> +FwCfgDataAddress = SwapBytes64 (Reg[0]);
> +FwCfgDataSize= 8;
> +FwCfgSelectorAddress = FwCfgDataAddress + FwCfgDataSize;
> +
[edk2-devel] [PATCH v4 4/8] OvmfPkg: Add the QemuFwCfgMmioLib PEI stage version
Added the PEI stage library for QemuFwCfgMmioLib, which uses the FDT to
find the fw_cfg and parse it.
BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=4755
Cc: Ard Biesheuvel
Cc: Jiewen Yao
Cc: Gerd Hoffmann
Co-authored-by: Xianglai Li
Signed-off-by: Chao Li
---
.../Library/QemuFwCfgLib/QemuFwCfgMmioPei.c | 235 ++
.../QemuFwCfgLib/QemuFwCfgMmioPeiLib.inf | 52
2 files changed, 287 insertions(+)
create mode 100644 OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgMmioPei.c
create mode 100644 OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgMmioPeiLib.inf
diff --git a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgMmioPei.c
b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgMmioPei.c
new file mode 100644
index 00..055148de8e
--- /dev/null
+++ b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgMmioPei.c
@@ -0,0 +1,235 @@
+/** @file
+
+ Stateful and implicitly initialized fw_cfg library implementation.
+
+ Copyright (C) 2013 - 2014, Red Hat, Inc.
+ Copyright (c) 2011 - 2013, Intel Corporation. All rights reserved.
+ (C) Copyright 2021 Hewlett Packard Enterprise Development LP
+ Copyright (c) 2024 Loongson Technology Corporation Limited. All rights
reserved.
+
+ SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+#include
+
+#include
+#include
+#include
+#include
+#include
+
+#include
+
+#include "QemuFwCfgLibMmioInternal.h"
+
+/**
+ To get firmware configure selector address.
+
+ @param VOID
+
+ @retval firmware configure selector address
+**/
+UINTN
+EFIAPI
+QemuGetFwCfgSelectorAddress (
+ VOID
+ )
+{
+ QEMU_FW_CFG_RESOURCE *FwCfgResource;
+
+ FwCfgResource = QemuGetFwCfgResourceHob ();
+ ASSERT (FwCfgResource != NULL);
+
+ return FwCfgResource->FwCfgSelectorAddress;
+}
+
+/**
+ To get firmware configure Data address.
+
+ @param VOID
+
+ @retval firmware configure data address
+**/
+UINTN
+EFIAPI
+QemuGetFwCfgDataAddress (
+ VOID
+ )
+{
+ QEMU_FW_CFG_RESOURCE *FwCfgResource;
+
+ FwCfgResource = QemuGetFwCfgResourceHob ();
+ ASSERT (FwCfgResource != NULL);
+
+ return FwCfgResource->FwCfgDataAddress;
+}
+
+/**
+ To get firmware DMA address.
+
+ @param VOID
+
+ @retval firmware DMA address
+**/
+UINTN
+EFIAPI
+QemuGetFwCfgDmaAddress (
+ VOID
+ )
+{
+ QEMU_FW_CFG_RESOURCE *FwCfgResource;
+
+ FwCfgResource = QemuGetFwCfgResourceHob ();
+ ASSERT (FwCfgResource != NULL);
+
+ return FwCfgResource->FwCfgDmaAddress;
+}
+
+RETURN_STATUS
+EFIAPI
+QemuFwCfgInitialize (
+ VOID
+ )
+{
+ VOID *DeviceTreeBase;
+ INT32 Node;
+ INT32 Prev;
+ CONST CHAR8 *Type;
+ INT32 Len;
+ CONST UINT64 *Reg;
+ UINT64FwCfgSelectorAddress;
+ UINT64FwCfgSelectorSize;
+ UINT64FwCfgDataAddress;
+ UINT64FwCfgDataSize;
+ UINT64FwCfgDmaAddress;
+ UINT64FwCfgDmaSize;
+ QEMU_FW_CFG_RESOURCE *FwCfgResource;
+ VOID *Buffer;
+
+ //
+ // Check whether the Qemu firmware configure resources HOB has been created,
+ // if so use the resources in the HOB.
+ //
+ FwCfgResource = QemuGetFwCfgResourceHob ();
+ if (FwCfgResource != NULL) {
+return RETURN_SUCCESS;
+ }
+
+ DeviceTreeBase = (VOID *)(UINTN)PcdGet64 (PcdDeviceTreeInitialBaseAddress);
+ ASSERT (DeviceTreeBase != NULL);
+ //
+ // Make sure we have a valid device tree blob
+ //
+ ASSERT (fdt_check_header (DeviceTreeBase) == 0);
+
+ //
+ // Create resouce memory
+ //
+ Buffer = AllocatePages(EFI_SIZE_TO_PAGES (sizeof (QEMU_FW_CFG_RESOURCE)));
+ ASSERT (Buffer != NULL);
+ ZeroMem (Buffer, sizeof (QEMU_FW_CFG_RESOURCE));
+
+ FwCfgResource = (QEMU_FW_CFG_RESOURCE *)Buffer;
+
+ for (Prev = 0; ; Prev = Node) {
+Node = fdt_next_node (DeviceTreeBase, Prev, NULL);
+if (Node < 0) {
+ break;
+}
+
+//
+// Check for memory node
+//
+Type = fdt_getprop (DeviceTreeBase, Node, "compatible", &Len);
+if ((Type) &&
+(AsciiStrnCmp (Type, "qemu,fw-cfg-mmio", Len) == 0))
+{
+ //
+ // Get the 'reg' property of this node. For now, we will assume
+ // two 8 byte quantities for base and size, respectively.
+ //
+ Reg = fdt_getprop (DeviceTreeBase, Node, "reg", &Len);
+ if ((Reg != 0) && (Len == (2 * sizeof (UINT64 {
+FwCfgDataAddress = SwapBytes64 (Reg[0]);
+FwCfgDataSize= 8;
+FwCfgSelectorAddress = FwCfgDataAddress + FwCfgDataSize;
+FwCfgSelectorSize= 2;
+
+//
+// The following ASSERT()s express
+//
+// Address + Size - 1 <= MAX_UINTN
+//
+// for both registers, that is, that the last byte in each MMIO range
is
+// expressible as a MAX_UINTN. The form below is mathematically
+// equivalent, and it also prevents any unsigned overflow before the
+// comparison.
+//
+ASSERT (FwCfgSelectorAddress <= MAX_UINTN - FwCfgSelectorSize + 1);
+
