diff options
Diffstat (limited to 'ArmVirtPkg/VirtFdtDxe/VirtFdtDxe.c')
| -rw-r--r-- | ArmVirtPkg/VirtFdtDxe/VirtFdtDxe.c | 566 |
1 files changed, 566 insertions, 0 deletions
diff --git a/ArmVirtPkg/VirtFdtDxe/VirtFdtDxe.c b/ArmVirtPkg/VirtFdtDxe/VirtFdtDxe.c new file mode 100644 index 0000000000..c9a181a871 --- /dev/null +++ b/ArmVirtPkg/VirtFdtDxe/VirtFdtDxe.c @@ -0,0 +1,566 @@ +/** @file
+* Device tree enumeration DXE driver for ARM Virtual Machines
+*
+* Copyright (c) 2014, Linaro Ltd. All rights reserved.<BR>
+*
+* 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 <Library/BaseLib.h>
+#include <Library/DebugLib.h>
+#include <Library/UefiLib.h>
+#include <Library/BaseMemoryLib.h>
+#include <Library/UefiDriverEntryPoint.h>
+#include <Library/MemoryAllocationLib.h>
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/VirtioMmioDeviceLib.h>
+#include <Library/DevicePathLib.h>
+#include <Library/PcdLib.h>
+#include <Library/DxeServicesLib.h>
+#include <Library/HobLib.h>
+#include <libfdt.h>
+#include <Library/XenIoMmioLib.h>
+
+#include <Guid/Fdt.h>
+#include <Guid/VirtioMmioTransport.h>
+#include <Guid/FdtHob.h>
+
+#pragma pack (1)
+typedef struct {
+ VENDOR_DEVICE_PATH Vendor;
+ UINT64 PhysBase;
+ EFI_DEVICE_PATH_PROTOCOL End;
+} VIRTIO_TRANSPORT_DEVICE_PATH;
+#pragma pack ()
+
+typedef enum {
+ PropertyTypeUnknown,
+ PropertyTypeGic,
+ PropertyTypeRtc,
+ PropertyTypeVirtio,
+ PropertyTypeUart,
+ PropertyTypeTimer,
+ PropertyTypePsci,
+ PropertyTypeFwCfg,
+ PropertyTypePciHost,
+ PropertyTypeGicV3,
+ PropertyTypeXen,
+} PROPERTY_TYPE;
+
+typedef struct {
+ PROPERTY_TYPE Type;
+ CHAR8 Compatible[32];
+} PROPERTY;
+
+STATIC CONST PROPERTY CompatibleProperties[] = {
+ { PropertyTypeGic, "arm,cortex-a15-gic" },
+ { PropertyTypeRtc, "arm,pl031" },
+ { PropertyTypeVirtio, "virtio,mmio" },
+ { PropertyTypeUart, "arm,pl011" },
+ { PropertyTypeTimer, "arm,armv7-timer" },
+ { PropertyTypeTimer, "arm,armv8-timer" },
+ { PropertyTypePsci, "arm,psci-0.2" },
+ { PropertyTypeFwCfg, "qemu,fw-cfg-mmio" },
+ { PropertyTypePciHost, "pci-host-ecam-generic" },
+ { PropertyTypeGicV3, "arm,gic-v3" },
+ { PropertyTypeXen, "xen,xen" },
+ { PropertyTypeUnknown, "" }
+};
+
+typedef struct {
+ UINT32 Type;
+ UINT32 Number;
+ UINT32 Flags;
+} INTERRUPT_PROPERTY;
+
+STATIC
+PROPERTY_TYPE
+GetTypeFromNode (
+ IN CONST CHAR8 *NodeType,
+ IN UINTN Size
+ )
+{
+ CONST CHAR8 *Compatible;
+ CONST PROPERTY *CompatibleProperty;
+
+ //
+ // A 'compatible' node may contain a sequence of NULL terminated
+ // compatible strings so check each one
+ //
+ for (Compatible = NodeType; Compatible < NodeType + Size && *Compatible;
+ Compatible += 1 + AsciiStrLen (Compatible)) {
+ for (CompatibleProperty = CompatibleProperties; CompatibleProperty->Compatible[0]; CompatibleProperty++) {
+ if (AsciiStrCmp (CompatibleProperty->Compatible, Compatible) == 0) {
+ return CompatibleProperty->Type;
+ }
+ }
+ }
+ return PropertyTypeUnknown;
+}
+
+//
+// We expect the "ranges" property of "pci-host-ecam-generic" to consist of
+// records like this.
+//
+#pragma pack (1)
+typedef struct {
+ UINT32 Type;
+ UINT64 ChildBase;
+ UINT64 CpuBase;
+ UINT64 Size;
+} DTB_PCI_HOST_RANGE_RECORD;
+#pragma pack ()
+
+#define DTB_PCI_HOST_RANGE_RELOCATABLE BIT31
+#define DTB_PCI_HOST_RANGE_PREFETCHABLE BIT30
+#define DTB_PCI_HOST_RANGE_ALIASED BIT29
+#define DTB_PCI_HOST_RANGE_MMIO32 BIT25
+#define DTB_PCI_HOST_RANGE_MMIO64 (BIT25 | BIT24)
+#define DTB_PCI_HOST_RANGE_IO BIT24
+#define DTB_PCI_HOST_RANGE_TYPEMASK (BIT31 | BIT30 | BIT29 | BIT25 | BIT24)
+
+/**
+ Process the device tree node describing the generic PCI host controller.
+
+ param[in] DeviceTreeBase Pointer to the device tree.
+
+ param[in] Node Offset of the device tree node whose "compatible"
+ property is "pci-host-ecam-generic".
+
+ param[in] RegProp Pointer to the "reg" property of Node. The caller
+ is responsible for ensuring that the size of the
+ property is 4 UINT32 cells.
+
+ @retval EFI_SUCCESS Parsing successful, properties parsed from Node
+ have been stored in dynamic PCDs.
+
+ @retval EFI_PROTOCOL_ERROR Parsing failed. PCDs are left unchanged.
+**/
+STATIC
+EFI_STATUS
+EFIAPI
+ProcessPciHost (
+ IN CONST VOID *DeviceTreeBase,
+ IN INT32 Node,
+ IN CONST VOID *RegProp
+ )
+{
+ UINT64 ConfigBase, ConfigSize;
+ CONST VOID *Prop;
+ INT32 Len;
+ UINT32 BusMin, BusMax;
+ UINT32 RecordIdx;
+ UINT64 IoBase, IoSize, IoTranslation;
+ UINT64 MmioBase, MmioSize, MmioTranslation;
+
+ //
+ // Fetch the ECAM window.
+ //
+ ConfigBase = fdt64_to_cpu (((CONST UINT64 *)RegProp)[0]);
+ ConfigSize = fdt64_to_cpu (((CONST UINT64 *)RegProp)[1]);
+
+ //
+ // Fetch the bus range (note: inclusive).
+ //
+ Prop = fdt_getprop (DeviceTreeBase, Node, "bus-range", &Len);
+ if (Prop == NULL || Len != 2 * sizeof(UINT32)) {
+ DEBUG ((EFI_D_ERROR, "%a: 'bus-range' not found or invalid\n",
+ __FUNCTION__));
+ return EFI_PROTOCOL_ERROR;
+ }
+ BusMin = fdt32_to_cpu (((CONST UINT32 *)Prop)[0]);
+ BusMax = fdt32_to_cpu (((CONST UINT32 *)Prop)[1]);
+
+ //
+ // Sanity check: the config space must accommodate all 4K register bytes of
+ // all 8 functions of all 32 devices of all buses.
+ //
+ if (BusMax < BusMin || BusMax - BusMin == MAX_UINT32 ||
+ DivU64x32 (ConfigSize, SIZE_4KB * 8 * 32) < BusMax - BusMin + 1) {
+ DEBUG ((EFI_D_ERROR, "%a: invalid 'bus-range' and/or 'reg'\n",
+ __FUNCTION__));
+ return EFI_PROTOCOL_ERROR;
+ }
+
+ //
+ // Iterate over "ranges".
+ //
+ Prop = fdt_getprop (DeviceTreeBase, Node, "ranges", &Len);
+ if (Prop == NULL || Len == 0 ||
+ Len % sizeof (DTB_PCI_HOST_RANGE_RECORD) != 0) {
+ DEBUG ((EFI_D_ERROR, "%a: 'ranges' not found or invalid\n", __FUNCTION__));
+ return EFI_PROTOCOL_ERROR;
+ }
+
+ //
+ // IoBase, IoTranslation, MmioBase and MmioTranslation are initialized only
+ // in order to suppress '-Werror=maybe-uninitialized' warnings *incorrectly*
+ // emitted by some gcc versions.
+ //
+ IoBase = 0;
+ IoTranslation = 0;
+ MmioBase = 0;
+ MmioTranslation = 0;
+
+ //
+ // IoSize and MmioSize are initialized to zero because the logic below
+ // requires it.
+ //
+ IoSize = 0;
+ MmioSize = 0;
+ for (RecordIdx = 0; RecordIdx < Len / sizeof (DTB_PCI_HOST_RANGE_RECORD);
+ ++RecordIdx) {
+ CONST DTB_PCI_HOST_RANGE_RECORD *Record;
+
+ Record = (CONST DTB_PCI_HOST_RANGE_RECORD *)Prop + RecordIdx;
+ switch (fdt32_to_cpu (Record->Type) & DTB_PCI_HOST_RANGE_TYPEMASK) {
+ case DTB_PCI_HOST_RANGE_IO:
+ IoBase = fdt64_to_cpu (Record->ChildBase);
+ IoSize = fdt64_to_cpu (Record->Size);
+ IoTranslation = fdt64_to_cpu (Record->CpuBase) - IoBase;
+ break;
+
+ case DTB_PCI_HOST_RANGE_MMIO32:
+ MmioBase = fdt64_to_cpu (Record->ChildBase);
+ MmioSize = fdt64_to_cpu (Record->Size);
+ MmioTranslation = fdt64_to_cpu (Record->CpuBase) - MmioBase;
+
+ if (MmioBase > MAX_UINT32 || MmioSize > MAX_UINT32 ||
+ MmioBase + MmioSize > SIZE_4GB) {
+ DEBUG ((EFI_D_ERROR, "%a: MMIO32 space invalid\n", __FUNCTION__));
+ return EFI_PROTOCOL_ERROR;
+ }
+
+ if (MmioTranslation != 0) {
+ DEBUG ((EFI_D_ERROR, "%a: unsupported nonzero MMIO32 translation "
+ "0x%Lx\n", __FUNCTION__, MmioTranslation));
+ return EFI_UNSUPPORTED;
+ }
+
+ break;
+ }
+ }
+ if (IoSize == 0 || MmioSize == 0) {
+ DEBUG ((EFI_D_ERROR, "%a: %a space empty\n", __FUNCTION__,
+ (IoSize == 0) ? "IO" : "MMIO32"));
+ return EFI_PROTOCOL_ERROR;
+ }
+
+ PcdSet64 (PcdPciExpressBaseAddress, ConfigBase);
+
+ PcdSet32 (PcdPciBusMin, BusMin);
+ PcdSet32 (PcdPciBusMax, BusMax);
+
+ PcdSet64 (PcdPciIoBase, IoBase);
+ PcdSet64 (PcdPciIoSize, IoSize);
+ PcdSet64 (PcdPciIoTranslation, IoTranslation);
+
+ PcdSet32 (PcdPciMmio32Base, (UINT32)MmioBase);
+ PcdSet32 (PcdPciMmio32Size, (UINT32)MmioSize);
+
+ PcdSetBool (PcdPciDisableBusEnumeration, FALSE);
+
+ DEBUG ((EFI_D_INFO, "%a: Config[0x%Lx+0x%Lx) Bus[0x%x..0x%x] "
+ "Io[0x%Lx+0x%Lx)@0x%Lx Mem[0x%Lx+0x%Lx)@0x%Lx\n", __FUNCTION__, ConfigBase,
+ ConfigSize, BusMin, BusMax, IoBase, IoSize, IoTranslation, MmioBase,
+ MmioSize, MmioTranslation));
+ return EFI_SUCCESS;
+}
+
+
+EFI_STATUS
+EFIAPI
+InitializeVirtFdtDxe (
+ IN EFI_HANDLE ImageHandle,
+ IN EFI_SYSTEM_TABLE *SystemTable
+ )
+{
+ VOID *Hob;
+ VOID *DeviceTreeBase;
+ INT32 Node, Prev;
+ INT32 RtcNode;
+ EFI_STATUS Status;
+ CONST CHAR8 *Type;
+ INT32 Len;
+ PROPERTY_TYPE PropType;
+ CONST VOID *RegProp;
+ VIRTIO_TRANSPORT_DEVICE_PATH *DevicePath;
+ EFI_HANDLE Handle;
+ UINT64 RegBase;
+ UINT64 DistBase, CpuBase, RedistBase;
+ CONST INTERRUPT_PROPERTY *InterruptProp;
+ INT32 SecIntrNum, IntrNum, VirtIntrNum, HypIntrNum;
+ CONST CHAR8 *PsciMethod;
+ UINT64 FwCfgSelectorAddress;
+ UINT64 FwCfgSelectorSize;
+ UINT64 FwCfgDataAddress;
+ UINT64 FwCfgDataSize;
+
+ Hob = GetFirstGuidHob(&gFdtHobGuid);
+ if (Hob == NULL || GET_GUID_HOB_DATA_SIZE (Hob) != sizeof (UINT64)) {
+ return EFI_NOT_FOUND;
+ }
+ DeviceTreeBase = (VOID *)(UINTN)*(UINT64 *)GET_GUID_HOB_DATA (Hob);
+
+ if (fdt_check_header (DeviceTreeBase) != 0) {
+ DEBUG ((EFI_D_ERROR, "%a: No DTB found @ 0x%p\n", __FUNCTION__, DeviceTreeBase));
+ return EFI_NOT_FOUND;
+ }
+
+ Status = gBS->InstallConfigurationTable (&gFdtTableGuid, DeviceTreeBase);
+ ASSERT_EFI_ERROR (Status);
+
+ DEBUG ((EFI_D_INFO, "%a: DTB @ 0x%p\n", __FUNCTION__, DeviceTreeBase));
+
+ RtcNode = -1;
+ //
+ // Now enumerate the nodes and install peripherals that we are interested in,
+ // i.e., GIC, RTC and virtio MMIO nodes
+ //
+ for (Prev = 0;; Prev = Node) {
+ Node = fdt_next_node (DeviceTreeBase, Prev, NULL);
+ if (Node < 0) {
+ break;
+ }
+
+ Type = fdt_getprop (DeviceTreeBase, Node, "compatible", &Len);
+ if (Type == NULL) {
+ continue;
+ }
+
+ PropType = GetTypeFromNode (Type, Len);
+ if (PropType == PropertyTypeUnknown) {
+ continue;
+ }
+
+ //
+ // Get the 'reg' property of this node. For now, we will assume
+ // 8 byte quantities for base and size, respectively.
+ // TODO use #cells root properties instead
+ //
+ RegProp = fdt_getprop (DeviceTreeBase, Node, "reg", &Len);
+ ASSERT ((RegProp != NULL) || (PropType == PropertyTypeTimer) ||
+ (PropType == PropertyTypePsci));
+
+ switch (PropType) {
+ case PropertyTypePciHost:
+ ASSERT (Len == 2 * sizeof (UINT64));
+ Status = ProcessPciHost (DeviceTreeBase, Node, RegProp);
+ ASSERT_EFI_ERROR (Status);
+ break;
+
+ case PropertyTypeFwCfg:
+ ASSERT (Len == 2 * sizeof (UINT64));
+
+ FwCfgDataAddress = fdt64_to_cpu (((UINT64 *)RegProp)[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);
+ ASSERT (FwCfgDataAddress <= MAX_UINTN - FwCfgDataSize + 1);
+
+ PcdSet64 (PcdFwCfgSelectorAddress, FwCfgSelectorAddress);
+ PcdSet64 (PcdFwCfgDataAddress, FwCfgDataAddress);
+
+ DEBUG ((EFI_D_INFO, "Found FwCfg @ 0x%Lx/0x%Lx\n", FwCfgSelectorAddress,
+ FwCfgDataAddress));
+ break;
+
+ case PropertyTypeVirtio:
+ ASSERT (Len == 16);
+ //
+ // Create a unique device path for this transport on the fly
+ //
+ RegBase = fdt64_to_cpu (((UINT64 *)RegProp)[0]);
+ DevicePath = (VIRTIO_TRANSPORT_DEVICE_PATH *)CreateDeviceNode (
+ HARDWARE_DEVICE_PATH,
+ HW_VENDOR_DP,
+ sizeof (VIRTIO_TRANSPORT_DEVICE_PATH));
+ if (DevicePath == NULL) {
+ DEBUG ((EFI_D_ERROR, "%a: Out of memory\n", __FUNCTION__));
+ break;
+ }
+
+ CopyMem (&DevicePath->Vendor.Guid, &gVirtioMmioTransportGuid,
+ sizeof (EFI_GUID));
+ DevicePath->PhysBase = RegBase;
+ SetDevicePathNodeLength (&DevicePath->Vendor,
+ sizeof (*DevicePath) - sizeof (DevicePath->End));
+ SetDevicePathEndNode (&DevicePath->End);
+
+ Handle = NULL;
+ Status = gBS->InstallProtocolInterface (&Handle,
+ &gEfiDevicePathProtocolGuid, EFI_NATIVE_INTERFACE,
+ DevicePath);
+ if (EFI_ERROR (Status)) {
+ DEBUG ((EFI_D_ERROR, "%a: Failed to install the EFI_DEVICE_PATH "
+ "protocol on a new handle (Status == %r)\n",
+ __FUNCTION__, Status));
+ FreePool (DevicePath);
+ break;
+ }
+
+ Status = VirtioMmioInstallDevice (RegBase, Handle);
+ if (EFI_ERROR (Status)) {
+ DEBUG ((EFI_D_ERROR, "%a: Failed to install VirtIO transport @ 0x%Lx "
+ "on handle %p (Status == %r)\n", __FUNCTION__, RegBase,
+ Handle, Status));
+
+ Status = gBS->UninstallProtocolInterface (Handle,
+ &gEfiDevicePathProtocolGuid, DevicePath);
+ ASSERT_EFI_ERROR (Status);
+ FreePool (DevicePath);
+ }
+ break;
+
+ case PropertyTypeGic:
+ ASSERT (Len == 32);
+
+ DistBase = fdt64_to_cpu (((UINT64 *)RegProp)[0]);
+ CpuBase = fdt64_to_cpu (((UINT64 *)RegProp)[2]);
+ ASSERT (DistBase < MAX_UINT32);
+ ASSERT (CpuBase < MAX_UINT32);
+
+ PcdSet32 (PcdGicDistributorBase, (UINT32)DistBase);
+ PcdSet32 (PcdGicInterruptInterfaceBase, (UINT32)CpuBase);
+
+ DEBUG ((EFI_D_INFO, "Found GIC @ 0x%Lx/0x%Lx\n", DistBase, CpuBase));
+ break;
+
+ case PropertyTypeGicV3:
+ //
+ // The GIC v3 DT binding describes a series of at least 3 physical (base
+ // addresses, size) pairs: the distributor interface (GICD), at least one
+ // redistributor region (GICR) containing dedicated redistributor
+ // interfaces for all individual CPUs, and the CPU interface (GICC).
+ // Under virtualization, we assume that the first redistributor region
+ // listed covers the boot CPU. Also, our GICv3 driver only supports the
+ // system register CPU interface, so we can safely ignore the MMIO version
+ // which is listed after the sequence of redistributor interfaces.
+ // This means we are only interested in the first two memory regions
+ // supplied, and ignore everything else.
+ //
+ ASSERT (Len >= 32);
+
+ // RegProp[0..1] == { GICD base, GICD size }
+ DistBase = fdt64_to_cpu (((UINT64 *)RegProp)[0]);
+ ASSERT (DistBase < MAX_UINT32);
+
+ // RegProp[2..3] == { GICR base, GICR size }
+ RedistBase = fdt64_to_cpu (((UINT64 *)RegProp)[2]);
+ ASSERT (RedistBase < MAX_UINT32);
+
+ PcdSet32 (PcdGicDistributorBase, (UINT32)DistBase);
+ PcdSet32 (PcdGicRedistributorsBase, (UINT32)RedistBase);
+
+ DEBUG ((EFI_D_INFO, "Found GIC v3 (re)distributor @ 0x%Lx (0x%Lx)\n",
+ DistBase, RedistBase));
+ break;
+
+ case PropertyTypeRtc:
+ ASSERT (Len == 16);
+
+ RegBase = fdt64_to_cpu (((UINT64 *)RegProp)[0]);
+ ASSERT (RegBase < MAX_UINT32);
+
+ PcdSet32 (PcdPL031RtcBase, (UINT32)RegBase);
+
+ DEBUG ((EFI_D_INFO, "Found PL031 RTC @ 0x%Lx\n", RegBase));
+ RtcNode = Node;
+ break;
+
+ case PropertyTypeTimer:
+ //
+ // - interrupts : Interrupt list for secure, non-secure, virtual and
+ // hypervisor timers, in that order.
+ //
+ InterruptProp = fdt_getprop (DeviceTreeBase, Node, "interrupts", &Len);
+ ASSERT (Len == 36 || Len == 48);
+
+ SecIntrNum = fdt32_to_cpu (InterruptProp[0].Number)
+ + (InterruptProp[0].Type ? 16 : 0);
+ IntrNum = fdt32_to_cpu (InterruptProp[1].Number)
+ + (InterruptProp[1].Type ? 16 : 0);
+ VirtIntrNum = fdt32_to_cpu (InterruptProp[2].Number)
+ + (InterruptProp[2].Type ? 16 : 0);
+ HypIntrNum = Len < 48 ? 0 : fdt32_to_cpu (InterruptProp[3].Number)
+ + (InterruptProp[3].Type ? 16 : 0);
+
+ DEBUG ((EFI_D_INFO, "Found Timer interrupts %d, %d, %d, %d\n",
+ SecIntrNum, IntrNum, VirtIntrNum, HypIntrNum));
+
+ PcdSet32 (PcdArmArchTimerSecIntrNum, SecIntrNum);
+ PcdSet32 (PcdArmArchTimerIntrNum, IntrNum);
+ PcdSet32 (PcdArmArchTimerVirtIntrNum, VirtIntrNum);
+ PcdSet32 (PcdArmArchTimerHypIntrNum, HypIntrNum);
+ break;
+
+ case PropertyTypePsci:
+ PsciMethod = fdt_getprop (DeviceTreeBase, Node, "method", &Len);
+
+ if (PsciMethod && AsciiStrnCmp (PsciMethod, "hvc", 3) == 0) {
+ PcdSet32 (PcdArmPsciMethod, 1);
+ } else if (PsciMethod && AsciiStrnCmp (PsciMethod, "smc", 3) == 0) {
+ PcdSet32 (PcdArmPsciMethod, 2);
+ } else {
+ DEBUG ((EFI_D_ERROR, "%a: Unknown PSCI method \"%a\"\n", __FUNCTION__,
+ PsciMethod));
+ }
+ break;
+
+ case PropertyTypeXen:
+ ASSERT (Len == 16);
+
+ //
+ // Retrieve the reg base from this node and wire it up to the
+ // MMIO flavor of the XenBus root device I/O protocol
+ //
+ RegBase = fdt64_to_cpu (((UINT64 *)RegProp)[0]);
+ Handle = NULL;
+ Status = XenIoMmioInstall (&Handle, RegBase);
+ if (EFI_ERROR (Status)) {
+ DEBUG ((EFI_D_ERROR, "%a: XenIoMmioInstall () failed on a new handle "
+ "(Status == %r)\n", __FUNCTION__, Status));
+ break;
+ }
+
+ DEBUG ((EFI_D_INFO, "Found Xen node with Grant table @ 0x%Lx\n", RegBase));
+
+ break;
+
+ default:
+ break;
+ }
+ }
+
+ //
+ // UEFI takes ownership of the RTC hardware, and exposes its functionality
+ // through the UEFI Runtime Services GetTime, SetTime, etc. This means we
+ // need to disable it in the device tree to prevent the OS from attaching its
+ // device driver as well.
+ //
+ if ((RtcNode != -1) &&
+ fdt_setprop_string (DeviceTreeBase, RtcNode, "status",
+ "disabled") != 0) {
+ DEBUG ((EFI_D_WARN, "Failed to set PL031 status to 'disabled'\n"));
+ }
+ return EFI_SUCCESS;
+}
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