audk/OvmfPkg/Library/VirtioMmioDeviceLib/VirtioMmioDeviceFunctions.c

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OvmfPkg/VirtioMmioDeviceLib: Implement VIRTIO_DEVICE_PROTOCOL for VirtIo Devices over MMIO Why is the virtio-mmio implementation of the protocol a library, instead of a driver binary? The UEFI driver model would encourage to create a virtio-mmio driver instead of a library. But the reasons why I created a library are: - A virtio-mmio driver would imply an additional protocol that would probably have a single attribute field: typedef struct { PHYSICAL_ADDRESS BaseAddress; } VIRTIO_MMIO_DEVICE_PROTOCOL; - There is no (easy) way to scan the available VirtIo devices on a platform. So, the UEFI firmware for this platform would need a driver to produce instances for every virtio devices it wants to expose in UEFI. A single call to a helper library (ie: VirtioMmioDeviceLib) make the porting easier. Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Olivier Martin <olivier.martin@arm.com> v5: - typo fix in VirtioMmioInstallDevice() comment block - plug MmioDevice leak in VirtioMmioUninstallDevice() - return EFI_INVALID_PARAMETER in VirtioMmioGetQueueAddress() if QueueAddress is NULL - VirtioMmioSetQueueSize(): fix return value (it's a status code) - VirtioMmioSetPageSize(): check against EFI_PAGE_SIZE with "if" plus EFI_UNSUPPORTED, rather than ASSERT() - VirtioMmioDeviceWrite(), VirtioMmioDeviceRead(): remove redundant (FieldSize > 8) checks - VirtioMmioDeviceLib.inf: drop UefiDriverEntryPoint library dependency 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@14965 6f19259b-4bc3-4df7-8a09-765794883524
2013-12-11 17:57:59 +01:00
/** @file
This driver produces Virtio Device Protocol instances for Virtio MMIO devices.
Copyright (C) 2012, Red Hat, Inc.
Copyright (c) 2012, Intel Corporation. All rights reserved.<BR>
Copyright (C) 2013, ARM Ltd.
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 "VirtioMmioDevice.h"
EFI_STATUS
EFIAPI
VirtioMmioGetDeviceFeatures (
IN VIRTIO_DEVICE_PROTOCOL *This,
OvmfPkg: VIRTIO_DEVICE_PROTOCOL: widen the Features bitmap to 64 bits The virtio-1.0 spec widens the Features bitmap to 64 bits. Modify the declarations of the GetDeviceFeatures() and SetGuestFeatures() protocol member functions accordingly. Normally, a protocol cannot be changed in incompatible ways if the GUID stays the same; however, we've always been extremely clear that VIRTIO_DEVICE_PROTOCOL is internal to edk2. See for example the top of "OvmfPkg/Include/Protocol/VirtioDevice.h". In this patch, all producers and consumers of the GetDeviceFeatures() and SetGuestFeatures() protocol members are updated. The drivers that currently produce these members are "legacy" drivers (in virtio-1.0 terminology), and they cannot (and will not) handle feature bits above BIT31. Therefore their conversion is only for compatibility with the modified protocol interface. The consumers will be responsible for checking the VIRTIO_DEVICE_PROTOCOL.Revision field, and for not passing feature bits that these backends cannot handle. The VirtioMmioGetDeviceFeatures() implementation stores the result of an MmioRead32() call with normal assignment, so it needs no change beyond adapting its prototype. Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Jordan Justen <jordan.l.justen@intel.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
2016-03-12 00:58:12 +01:00
OUT UINT64 *DeviceFeatures
OvmfPkg/VirtioMmioDeviceLib: Implement VIRTIO_DEVICE_PROTOCOL for VirtIo Devices over MMIO Why is the virtio-mmio implementation of the protocol a library, instead of a driver binary? The UEFI driver model would encourage to create a virtio-mmio driver instead of a library. But the reasons why I created a library are: - A virtio-mmio driver would imply an additional protocol that would probably have a single attribute field: typedef struct { PHYSICAL_ADDRESS BaseAddress; } VIRTIO_MMIO_DEVICE_PROTOCOL; - There is no (easy) way to scan the available VirtIo devices on a platform. So, the UEFI firmware for this platform would need a driver to produce instances for every virtio devices it wants to expose in UEFI. A single call to a helper library (ie: VirtioMmioDeviceLib) make the porting easier. Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Olivier Martin <olivier.martin@arm.com> v5: - typo fix in VirtioMmioInstallDevice() comment block - plug MmioDevice leak in VirtioMmioUninstallDevice() - return EFI_INVALID_PARAMETER in VirtioMmioGetQueueAddress() if QueueAddress is NULL - VirtioMmioSetQueueSize(): fix return value (it's a status code) - VirtioMmioSetPageSize(): check against EFI_PAGE_SIZE with "if" plus EFI_UNSUPPORTED, rather than ASSERT() - VirtioMmioDeviceWrite(), VirtioMmioDeviceRead(): remove redundant (FieldSize > 8) checks - VirtioMmioDeviceLib.inf: drop UefiDriverEntryPoint library dependency 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@14965 6f19259b-4bc3-4df7-8a09-765794883524
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)
{
VIRTIO_MMIO_DEVICE *Device;
if (DeviceFeatures == NULL) {
return EFI_INVALID_PARAMETER;
}
Device = VIRTIO_MMIO_DEVICE_FROM_VIRTIO_DEVICE (This);
*DeviceFeatures = VIRTIO_CFG_READ (Device, VIRTIO_MMIO_OFFSET_HOST_FEATURES);
return EFI_SUCCESS;
}
EFI_STATUS
EFIAPI
VirtioMmioGetQueueSize (
IN VIRTIO_DEVICE_PROTOCOL *This,
OUT UINT16 *QueueNumMax
)
{
VIRTIO_MMIO_DEVICE *Device;
if (QueueNumMax == NULL) {
return EFI_INVALID_PARAMETER;
}
Device = VIRTIO_MMIO_DEVICE_FROM_VIRTIO_DEVICE (This);
*QueueNumMax = VIRTIO_CFG_READ (Device, VIRTIO_MMIO_OFFSET_QUEUE_NUM_MAX) & 0xFFFF;
return EFI_SUCCESS;
}
EFI_STATUS
EFIAPI
VirtioMmioGetDeviceStatus (
IN VIRTIO_DEVICE_PROTOCOL *This,
OUT UINT8 *DeviceStatus
)
{
VIRTIO_MMIO_DEVICE *Device;
if (DeviceStatus == NULL) {
return EFI_INVALID_PARAMETER;
}
Device = VIRTIO_MMIO_DEVICE_FROM_VIRTIO_DEVICE (This);
*DeviceStatus = VIRTIO_CFG_READ (Device, VIRTIO_MMIO_OFFSET_STATUS) & 0xFF;
return EFI_SUCCESS;
}
EFI_STATUS
EFIAPI
VirtioMmioSetQueueSize (
VIRTIO_DEVICE_PROTOCOL *This,
UINT16 QueueSize
)
{
VIRTIO_MMIO_DEVICE *Device;
Device = VIRTIO_MMIO_DEVICE_FROM_VIRTIO_DEVICE (This);
VIRTIO_CFG_WRITE (Device, VIRTIO_MMIO_OFFSET_QUEUE_NUM, QueueSize);
return EFI_SUCCESS;
}
EFI_STATUS
EFIAPI
VirtioMmioSetDeviceStatus (
VIRTIO_DEVICE_PROTOCOL *This,
UINT8 DeviceStatus
)
{
VIRTIO_MMIO_DEVICE *Device;
Device = VIRTIO_MMIO_DEVICE_FROM_VIRTIO_DEVICE (This);
VIRTIO_CFG_WRITE (Device, VIRTIO_MMIO_OFFSET_STATUS, DeviceStatus);
return EFI_SUCCESS;
}
EFI_STATUS
EFIAPI
VirtioMmioSetQueueNotify (
VIRTIO_DEVICE_PROTOCOL *This,
UINT16 QueueNotify
)
{
VIRTIO_MMIO_DEVICE *Device;
Device = VIRTIO_MMIO_DEVICE_FROM_VIRTIO_DEVICE (This);
VIRTIO_CFG_WRITE (Device, VIRTIO_MMIO_OFFSET_QUEUE_NOTIFY, QueueNotify);
return EFI_SUCCESS;
}
EFI_STATUS
EFIAPI
VirtioMmioSetQueueAlignment (
VIRTIO_DEVICE_PROTOCOL *This,
UINT32 Alignment
)
{
VIRTIO_MMIO_DEVICE *Device;
Device = VIRTIO_MMIO_DEVICE_FROM_VIRTIO_DEVICE (This);
VIRTIO_CFG_WRITE (Device, VIRTIO_MMIO_OFFSET_QUEUE_ALIGN, Alignment);
return EFI_SUCCESS;
}
EFI_STATUS
EFIAPI
VirtioMmioSetPageSize (
VIRTIO_DEVICE_PROTOCOL *This,
UINT32 PageSize
)
{
VIRTIO_MMIO_DEVICE *Device;
if (PageSize != EFI_PAGE_SIZE) {
return EFI_UNSUPPORTED;
}
Device = VIRTIO_MMIO_DEVICE_FROM_VIRTIO_DEVICE (This);
VIRTIO_CFG_WRITE (Device, VIRTIO_MMIO_OFFSET_GUEST_PAGE_SIZE, PageSize);
return EFI_SUCCESS;
}
EFI_STATUS
EFIAPI
VirtioMmioSetQueueSel (
VIRTIO_DEVICE_PROTOCOL *This,
UINT16 Sel
)
{
VIRTIO_MMIO_DEVICE *Device;
Device = VIRTIO_MMIO_DEVICE_FROM_VIRTIO_DEVICE (This);
VIRTIO_CFG_WRITE (Device, VIRTIO_MMIO_OFFSET_QUEUE_SEL, Sel);
return EFI_SUCCESS;
}
EFI_STATUS
VirtioMmioSetQueueAddress (
IN VIRTIO_DEVICE_PROTOCOL *This,
IN VRING *Ring
OvmfPkg/VirtioMmioDeviceLib: Implement VIRTIO_DEVICE_PROTOCOL for VirtIo Devices over MMIO Why is the virtio-mmio implementation of the protocol a library, instead of a driver binary? The UEFI driver model would encourage to create a virtio-mmio driver instead of a library. But the reasons why I created a library are: - A virtio-mmio driver would imply an additional protocol that would probably have a single attribute field: typedef struct { PHYSICAL_ADDRESS BaseAddress; } VIRTIO_MMIO_DEVICE_PROTOCOL; - There is no (easy) way to scan the available VirtIo devices on a platform. So, the UEFI firmware for this platform would need a driver to produce instances for every virtio devices it wants to expose in UEFI. A single call to a helper library (ie: VirtioMmioDeviceLib) make the porting easier. Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Olivier Martin <olivier.martin@arm.com> v5: - typo fix in VirtioMmioInstallDevice() comment block - plug MmioDevice leak in VirtioMmioUninstallDevice() - return EFI_INVALID_PARAMETER in VirtioMmioGetQueueAddress() if QueueAddress is NULL - VirtioMmioSetQueueSize(): fix return value (it's a status code) - VirtioMmioSetPageSize(): check against EFI_PAGE_SIZE with "if" plus EFI_UNSUPPORTED, rather than ASSERT() - VirtioMmioDeviceWrite(), VirtioMmioDeviceRead(): remove redundant (FieldSize > 8) checks - VirtioMmioDeviceLib.inf: drop UefiDriverEntryPoint library dependency 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@14965 6f19259b-4bc3-4df7-8a09-765794883524
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)
{
VIRTIO_MMIO_DEVICE *Device;
Device = VIRTIO_MMIO_DEVICE_FROM_VIRTIO_DEVICE (This);
VIRTIO_CFG_WRITE (Device, VIRTIO_MMIO_OFFSET_QUEUE_PFN,
(UINT32)((UINTN)Ring->Base >> EFI_PAGE_SHIFT));
OvmfPkg/VirtioMmioDeviceLib: Implement VIRTIO_DEVICE_PROTOCOL for VirtIo Devices over MMIO Why is the virtio-mmio implementation of the protocol a library, instead of a driver binary? The UEFI driver model would encourage to create a virtio-mmio driver instead of a library. But the reasons why I created a library are: - A virtio-mmio driver would imply an additional protocol that would probably have a single attribute field: typedef struct { PHYSICAL_ADDRESS BaseAddress; } VIRTIO_MMIO_DEVICE_PROTOCOL; - There is no (easy) way to scan the available VirtIo devices on a platform. So, the UEFI firmware for this platform would need a driver to produce instances for every virtio devices it wants to expose in UEFI. A single call to a helper library (ie: VirtioMmioDeviceLib) make the porting easier. Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Olivier Martin <olivier.martin@arm.com> v5: - typo fix in VirtioMmioInstallDevice() comment block - plug MmioDevice leak in VirtioMmioUninstallDevice() - return EFI_INVALID_PARAMETER in VirtioMmioGetQueueAddress() if QueueAddress is NULL - VirtioMmioSetQueueSize(): fix return value (it's a status code) - VirtioMmioSetPageSize(): check against EFI_PAGE_SIZE with "if" plus EFI_UNSUPPORTED, rather than ASSERT() - VirtioMmioDeviceWrite(), VirtioMmioDeviceRead(): remove redundant (FieldSize > 8) checks - VirtioMmioDeviceLib.inf: drop UefiDriverEntryPoint library dependency 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@14965 6f19259b-4bc3-4df7-8a09-765794883524
2013-12-11 17:57:59 +01:00
return EFI_SUCCESS;
}
EFI_STATUS
EFIAPI
VirtioMmioSetGuestFeatures (
VIRTIO_DEVICE_PROTOCOL *This,
OvmfPkg: VIRTIO_DEVICE_PROTOCOL: widen the Features bitmap to 64 bits The virtio-1.0 spec widens the Features bitmap to 64 bits. Modify the declarations of the GetDeviceFeatures() and SetGuestFeatures() protocol member functions accordingly. Normally, a protocol cannot be changed in incompatible ways if the GUID stays the same; however, we've always been extremely clear that VIRTIO_DEVICE_PROTOCOL is internal to edk2. See for example the top of "OvmfPkg/Include/Protocol/VirtioDevice.h". In this patch, all producers and consumers of the GetDeviceFeatures() and SetGuestFeatures() protocol members are updated. The drivers that currently produce these members are "legacy" drivers (in virtio-1.0 terminology), and they cannot (and will not) handle feature bits above BIT31. Therefore their conversion is only for compatibility with the modified protocol interface. The consumers will be responsible for checking the VIRTIO_DEVICE_PROTOCOL.Revision field, and for not passing feature bits that these backends cannot handle. The VirtioMmioGetDeviceFeatures() implementation stores the result of an MmioRead32() call with normal assignment, so it needs no change beyond adapting its prototype. Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Jordan Justen <jordan.l.justen@intel.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
2016-03-12 00:58:12 +01:00
UINT64 Features
OvmfPkg/VirtioMmioDeviceLib: Implement VIRTIO_DEVICE_PROTOCOL for VirtIo Devices over MMIO Why is the virtio-mmio implementation of the protocol a library, instead of a driver binary? The UEFI driver model would encourage to create a virtio-mmio driver instead of a library. But the reasons why I created a library are: - A virtio-mmio driver would imply an additional protocol that would probably have a single attribute field: typedef struct { PHYSICAL_ADDRESS BaseAddress; } VIRTIO_MMIO_DEVICE_PROTOCOL; - There is no (easy) way to scan the available VirtIo devices on a platform. So, the UEFI firmware for this platform would need a driver to produce instances for every virtio devices it wants to expose in UEFI. A single call to a helper library (ie: VirtioMmioDeviceLib) make the porting easier. Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Olivier Martin <olivier.martin@arm.com> v5: - typo fix in VirtioMmioInstallDevice() comment block - plug MmioDevice leak in VirtioMmioUninstallDevice() - return EFI_INVALID_PARAMETER in VirtioMmioGetQueueAddress() if QueueAddress is NULL - VirtioMmioSetQueueSize(): fix return value (it's a status code) - VirtioMmioSetPageSize(): check against EFI_PAGE_SIZE with "if" plus EFI_UNSUPPORTED, rather than ASSERT() - VirtioMmioDeviceWrite(), VirtioMmioDeviceRead(): remove redundant (FieldSize > 8) checks - VirtioMmioDeviceLib.inf: drop UefiDriverEntryPoint library dependency 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@14965 6f19259b-4bc3-4df7-8a09-765794883524
2013-12-11 17:57:59 +01:00
)
{
VIRTIO_MMIO_DEVICE *Device;
Device = VIRTIO_MMIO_DEVICE_FROM_VIRTIO_DEVICE (This);
OvmfPkg: VIRTIO_DEVICE_PROTOCOL: widen the Features bitmap to 64 bits The virtio-1.0 spec widens the Features bitmap to 64 bits. Modify the declarations of the GetDeviceFeatures() and SetGuestFeatures() protocol member functions accordingly. Normally, a protocol cannot be changed in incompatible ways if the GUID stays the same; however, we've always been extremely clear that VIRTIO_DEVICE_PROTOCOL is internal to edk2. See for example the top of "OvmfPkg/Include/Protocol/VirtioDevice.h". In this patch, all producers and consumers of the GetDeviceFeatures() and SetGuestFeatures() protocol members are updated. The drivers that currently produce these members are "legacy" drivers (in virtio-1.0 terminology), and they cannot (and will not) handle feature bits above BIT31. Therefore their conversion is only for compatibility with the modified protocol interface. The consumers will be responsible for checking the VIRTIO_DEVICE_PROTOCOL.Revision field, and for not passing feature bits that these backends cannot handle. The VirtioMmioGetDeviceFeatures() implementation stores the result of an MmioRead32() call with normal assignment, so it needs no change beyond adapting its prototype. Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Jordan Justen <jordan.l.justen@intel.com> Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
2016-03-12 00:58:12 +01:00
if (Features > MAX_UINT32) {
return EFI_UNSUPPORTED;
}
VIRTIO_CFG_WRITE (Device, VIRTIO_MMIO_OFFSET_GUEST_FEATURES,
(UINT32)Features);
OvmfPkg/VirtioMmioDeviceLib: Implement VIRTIO_DEVICE_PROTOCOL for VirtIo Devices over MMIO Why is the virtio-mmio implementation of the protocol a library, instead of a driver binary? The UEFI driver model would encourage to create a virtio-mmio driver instead of a library. But the reasons why I created a library are: - A virtio-mmio driver would imply an additional protocol that would probably have a single attribute field: typedef struct { PHYSICAL_ADDRESS BaseAddress; } VIRTIO_MMIO_DEVICE_PROTOCOL; - There is no (easy) way to scan the available VirtIo devices on a platform. So, the UEFI firmware for this platform would need a driver to produce instances for every virtio devices it wants to expose in UEFI. A single call to a helper library (ie: VirtioMmioDeviceLib) make the porting easier. Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Olivier Martin <olivier.martin@arm.com> v5: - typo fix in VirtioMmioInstallDevice() comment block - plug MmioDevice leak in VirtioMmioUninstallDevice() - return EFI_INVALID_PARAMETER in VirtioMmioGetQueueAddress() if QueueAddress is NULL - VirtioMmioSetQueueSize(): fix return value (it's a status code) - VirtioMmioSetPageSize(): check against EFI_PAGE_SIZE with "if" plus EFI_UNSUPPORTED, rather than ASSERT() - VirtioMmioDeviceWrite(), VirtioMmioDeviceRead(): remove redundant (FieldSize > 8) checks - VirtioMmioDeviceLib.inf: drop UefiDriverEntryPoint library dependency 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@14965 6f19259b-4bc3-4df7-8a09-765794883524
2013-12-11 17:57:59 +01:00
return EFI_SUCCESS;
}
EFI_STATUS
EFIAPI
VirtioMmioDeviceWrite (
IN VIRTIO_DEVICE_PROTOCOL *This,
IN UINTN FieldOffset,
IN UINTN FieldSize,
IN UINT64 Value
)
{
UINTN DstBaseAddress;
VIRTIO_MMIO_DEVICE *Device;
Device = VIRTIO_MMIO_DEVICE_FROM_VIRTIO_DEVICE (This);
//
// Double-check fieldsize
//
if ((FieldSize != 1) && (FieldSize != 2) &&
(FieldSize != 4) && (FieldSize != 8)) {
return EFI_INVALID_PARAMETER;
}
//
// Compute base address
//
DstBaseAddress = Device->BaseAddress +
VIRTIO_DEVICE_SPECIFIC_CONFIGURATION_OFFSET_MMIO + FieldOffset;
//
// The device-specific memory area of Virtio-MMIO can only be written in
// byte accesses. This is not currently in the Virtio spec.
//
MmioWriteBuffer8 (DstBaseAddress, FieldSize, (UINT8*)&Value);
return EFI_SUCCESS;
}
EFI_STATUS
EFIAPI
VirtioMmioDeviceRead (
IN VIRTIO_DEVICE_PROTOCOL *This,
IN UINTN FieldOffset,
IN UINTN FieldSize,
IN UINTN BufferSize,
OUT VOID *Buffer
)
{
UINTN SrcBaseAddress;
VIRTIO_MMIO_DEVICE *Device;
Device = VIRTIO_MMIO_DEVICE_FROM_VIRTIO_DEVICE (This);
//
// Parameter validation
//
ASSERT (FieldSize == BufferSize);
//
// Double-check fieldsize
//
if ((FieldSize != 1) && (FieldSize != 2) &&
(FieldSize != 4) && (FieldSize != 8)) {
return EFI_INVALID_PARAMETER;
}
//
// Compute base address
//
SrcBaseAddress = Device->BaseAddress +
VIRTIO_DEVICE_SPECIFIC_CONFIGURATION_OFFSET_MMIO + FieldOffset;
//
// The device-specific memory area of Virtio-MMIO can only be read in
// byte reads. This is not currently in the Virtio spec.
//
MmioReadBuffer8 (SrcBaseAddress, BufferSize, Buffer);
return EFI_SUCCESS;
}