OvmfPkg/XenBusDxe/XenBus.c - third_party/edk2 - Git at Google

 /** @file
   XenBus Bus driver implemtation.

   This file implement the necessary to discover and enumerate Xen PV devices
   through XenStore.

   Copyright (C) 2010 Spectra Logic Corporation
   Copyright (C) 2008 Doug Rabson
   Copyright (C) 2005 Rusty Russell, IBM Corporation
   Copyright (C) 2005 Mike Wray, Hewlett-Packard
   Copyright (C) 2005 XenSource Ltd
   Copyright (C) 2014, Citrix Ltd.

   This file may be distributed separately from the Linux kernel, or
   incorporated into other software packages, subject to the following license:

   Permission is hereby granted, free of charge, to any person obtaining a copy
   of this source file (the "Software"), to deal in the Software without
   restriction, including without limitation the rights to use, copy, modify,
   merge, publish, distribute, sublicense, and/or sell copies of the Software,
   and to permit persons to whom the Software is furnished to do so, subject to
   the following conditions:

   The above copyright notice and this permission notice shall be included in
   all copies or substantial portions of the Software.

   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
   IN THE SOFTWARE.
 **/

 #include <Library/PrintLib.h>

 #include "XenBus.h"
 #include "GrantTable.h"
 #include "XenStore.h"
 #include "EventChannel.h"

 #include <IndustryStandard/Xen/io/xenbus.h>

 STATIC XENBUS_PRIVATE_DATA gXenBusPrivateData;

 STATIC XENBUS_DEVICE_PATH gXenBusDevicePathTemplate = {
   {                                                 // Vendor
     {                                               // Vendor.Header
       HARDWARE_DEVICE_PATH,                         // Vendor.Header.Type
       HW_VENDOR_DP,                                 // Vendor.Header.SubType
       {
         (UINT8) (sizeof (XENBUS_DEVICE_PATH)),      // Vendor.Header.Length[0]
         (UINT8) (sizeof (XENBUS_DEVICE_PATH) >> 8), // Vendor.Header.Length[1]
       }
     },
     XENBUS_PROTOCOL_GUID,                           // Vendor.Guid
   },
   0,                                                // Type
   0                                                 // DeviceId
 };


 /**
   Search our internal record of configured devices (not the XenStore) to
   determine if the XenBus device indicated by Node is known to the system.

   @param Dev   The XENBUS_DEVICE instance to search for device children.
   @param Node  The XenStore node path for the device to find.

   @return  The XENBUS_PRIVATE_DATA of the found device if any, or NULL.
  */
 STATIC
 XENBUS_PRIVATE_DATA *
 XenBusDeviceInitialized (
   IN XENBUS_DEVICE *Dev,
   IN CONST CHAR8 *Node
   )
 {
   LIST_ENTRY *Entry;
   XENBUS_PRIVATE_DATA *Child;
   XENBUS_PRIVATE_DATA *Result;

   if (IsListEmpty (&Dev->ChildList)) {
     return NULL;
   }

   Result = NULL;
   for (Entry = GetFirstNode (&Dev->ChildList);
        !IsNodeAtEnd (&Dev->ChildList, Entry);
        Entry = GetNextNode (&Dev->ChildList, Entry)) {
     Child = XENBUS_PRIVATE_DATA_FROM_LINK (Entry);
     if (!AsciiStrCmp (Child->XenBusIo.Node, Node)) {
       Result = Child;
       break;
     }
   }

   return (Result);
 }

 STATIC
 XenbusState
 XenBusReadDriverState (
   IN CONST CHAR8 *Path
   )
 {
   XenbusState State;
   CHAR8 *Ptr = NULL;
   XENSTORE_STATUS Status;

   Status = XenStoreRead (XST_NIL, Path, "state", NULL, (VOID **)&Ptr);
   if (Status != XENSTORE_STATUS_SUCCESS) {
     State = XenbusStateClosed;
   } else {
     State = AsciiStrDecimalToUintn (Ptr);
   }

   if (Ptr != NULL) {
     FreePool (Ptr);
   }

   return State;
 }

 //
 // Callers should ensure that they are only one calling XenBusAddDevice.
 //
 STATIC
 EFI_STATUS
 XenBusAddDevice (
   XENBUS_DEVICE *Dev,
   CONST CHAR8 *Type,
   CONST CHAR8 *Id)
 {
   CHAR8 DevicePath[XENSTORE_ABS_PATH_MAX];
   XENSTORE_STATUS StatusXenStore;
   XENBUS_PRIVATE_DATA *Private;
   EFI_STATUS Status;
   XENBUS_DEVICE_PATH *TempXenBusPath;
   VOID *ChildXenIo;

   AsciiSPrint (DevicePath, sizeof (DevicePath),
                "device/%a/%a", Type, Id);

   if (XenStorePathExists (XST_NIL, DevicePath, "")) {
     XENBUS_PRIVATE_DATA *Child;
     enum xenbus_state State;
     CHAR8 *BackendPath;

     Child = XenBusDeviceInitialized (Dev, DevicePath);
     if (Child != NULL) {
       /*
        * We are already tracking this node
        */
       Status = EFI_SUCCESS;
       goto out;
     }

     State = XenBusReadDriverState (DevicePath);
     if (State != XenbusStateInitialising) {
       /*
        * Device is not new, so ignore it. This can
        * happen if a device is going away after
        * switching to Closed.
        */
       DEBUG ((EFI_D_INFO, "XenBus: Device %a ignored. "
               "State %d\n", DevicePath, State));
       Status = EFI_SUCCESS;
       goto out;
     }

     StatusXenStore = XenStoreRead (XST_NIL, DevicePath, "backend",
                                    NULL, (VOID **) &BackendPath);
     if (StatusXenStore != XENSTORE_STATUS_SUCCESS) {
       DEBUG ((EFI_D_ERROR, "xenbus: %a no backend path.\n", DevicePath));
       Status = EFI_NOT_FOUND;
       goto out;
     }

     Private = AllocateCopyPool (sizeof (*Private), &gXenBusPrivateData);
     Private->XenBusIo.Type = AsciiStrDup (Type);
     Private->XenBusIo.Node = AsciiStrDup (DevicePath);
     Private->XenBusIo.Backend = BackendPath;
     Private->XenBusIo.DeviceId = (UINT16)AsciiStrDecimalToUintn (Id);
     Private->Dev = Dev;

     TempXenBusPath = AllocateCopyPool (sizeof (XENBUS_DEVICE_PATH),
                                        &gXenBusDevicePathTemplate);
     if (!AsciiStrCmp (Private->XenBusIo.Type, "vbd")) {
       TempXenBusPath->Type = XENBUS_DEVICE_PATH_TYPE_VBD;
     }
     TempXenBusPath->DeviceId = Private->XenBusIo.DeviceId;
     Private->DevicePath = (XENBUS_DEVICE_PATH *)AppendDevicePathNode (
                             Dev->DevicePath,
                             &TempXenBusPath->Vendor.Header);
     FreePool (TempXenBusPath);

     InsertTailList (&Dev->ChildList, &Private->Link);

     Status = gBS->InstallMultipleProtocolInterfaces (
                &Private->Handle,
                &gEfiDevicePathProtocolGuid, Private->DevicePath,
                &gXenBusProtocolGuid, &Private->XenBusIo,
                NULL);
     if (EFI_ERROR (Status)) {
       goto ErrorInstallProtocol;
     }

     Status = gBS->OpenProtocol (Dev->ControllerHandle,
                &gXenIoProtocolGuid,
                &ChildXenIo, Dev->This->DriverBindingHandle,
                Private->Handle,
                EFI_OPEN_PROTOCOL_BY_CHILD_CONTROLLER);
     if (EFI_ERROR (Status)) {
       DEBUG ((EFI_D_ERROR, "open by child controller fail (%r)\n",
               Status));
       goto ErrorOpenProtocolByChild;
     }
   } else {
     DEBUG ((EFI_D_ERROR, "XenBus: does not exist: %a\n", DevicePath));
     Status = EFI_NOT_FOUND;
   }

   return Status;

 ErrorOpenProtocolByChild:
   gBS->UninstallMultipleProtocolInterfaces (
     &Private->Handle,
     &gEfiDevicePathProtocolGuid, Private->DevicePath,
     &gXenBusProtocolGuid, &Private->XenBusIo,
     NULL);
 ErrorInstallProtocol:
   RemoveEntryList (&Private->Link);
   FreePool (Private->DevicePath);
   FreePool ((VOID *) Private->XenBusIo.Backend);
   FreePool ((VOID *) Private->XenBusIo.Node);
   FreePool ((VOID *) Private->XenBusIo.Type);
   FreePool (Private);
 out:
   return Status;
 }

 /**
   Enumerate all devices of the given type on this bus.

   @param Dev   A XENBUS_DEVICE instance.
   @param Type  String indicating the device sub-tree (e.g. "vfb", "vif")
                to enumerate.

   Devices that are found are been initialize via XenBusAddDevice ().
   XenBusAddDevice () ignores duplicate detects and ignores duplicate devices,
   so it can be called unconditionally for any device found in the XenStore.
  */
 STATIC
 VOID
 XenBusEnumerateDeviceType (
   XENBUS_DEVICE *Dev,
   CONST CHAR8 *Type
   )
 {
   CONST CHAR8 **Directory;
   UINTN Index;
   UINT32 Count;
   XENSTORE_STATUS Status;

   Status = XenStoreListDirectory (XST_NIL,
                                   "device", Type,
                                   &Count, &Directory);
   if (Status != XENSTORE_STATUS_SUCCESS) {
     return;
   }
   for (Index = 0; Index < Count; Index++) {
     XenBusAddDevice (Dev, Type, Directory[Index]);
   }

   FreePool ((VOID*)Directory);
 }


 /**
   Enumerate the devices on a XenBus bus and install a XenBus Protocol instance.

   Caller should ensure that it is the only one to call this function. This
   function cannot be called concurrently.

   @param Dev   A XENBUS_DEVICE instance.

   @return  On success, XENSTORE_STATUS_SUCCESS. Otherwise an errno value
            indicating the type of failure.
  */
 XENSTORE_STATUS
 XenBusEnumerateBus (
   XENBUS_DEVICE *Dev
   )
 {
   CONST CHAR8 **Types;
   UINTN Index;
   UINT32 Count;
   XENSTORE_STATUS Status;

   Status = XenStoreListDirectory (XST_NIL,
                                   "device", "",
                                   &Count, &Types);
   if (Status != XENSTORE_STATUS_SUCCESS) {
     return Status;
   }

   for (Index = 0; Index < Count; Index++) {
     XenBusEnumerateDeviceType (Dev, Types[Index]);
   }

   FreePool ((VOID*)Types);

   return XENSTORE_STATUS_SUCCESS;
 }

 STATIC
 XENSTORE_STATUS
 EFIAPI
 XenBusSetState (
   IN XENBUS_PROTOCOL      *This,
   IN CONST XENSTORE_TRANSACTION *Transaction,
   IN enum xenbus_state    NewState
   )
 {
   enum xenbus_state CurrentState;
   XENSTORE_STATUS Status;
   CHAR8 *Temp;

   DEBUG ((EFI_D_INFO, "XenBus: Set state to %d\n", NewState));

   Status = XenStoreRead (Transaction, This->Node, "state", NULL, (VOID **)&Temp);
   if (Status != XENSTORE_STATUS_SUCCESS) {
     goto Out;
   }
   CurrentState = AsciiStrDecimalToUintn (Temp);
   FreePool (Temp);
   if (CurrentState == NewState) {
     goto Out;
   }

   do {
     Status = XenStoreSPrint (Transaction, This->Node, "state", "%d", NewState);
   } while (Status == XENSTORE_STATUS_EAGAIN);
   if (Status != XENSTORE_STATUS_SUCCESS) {
     DEBUG ((EFI_D_ERROR, "XenBus: failed to write new state\n"));
     goto Out;
   }
   DEBUG ((EFI_D_INFO, "XenBus: Set state to %d, done\n", NewState));

 Out:
   return Status;
 }

 STATIC XENBUS_PRIVATE_DATA gXenBusPrivateData = {
   XENBUS_PRIVATE_DATA_SIGNATURE,    // Signature
   { NULL, NULL },                   // Link
   NULL,                             // Handle
   {                                 // XenBusIo
     XenBusXenStoreRead,             // XenBusIo.XsRead
     XenBusXenStoreBackendRead,      // XenBusIo.XsBackendRead
     XenBusXenStoreSPrint,           // XenBusIo.XsPrintf
     XenBusXenStoreRemove,           // XenBusIo.XsRemove
     XenBusXenStoreTransactionStart, // XenBusIo.XsTransactionStart
     XenBusXenStoreTransactionEnd,   // XenBusIo.XsTransactionEnd
     XenBusSetState,                 // XenBusIo.SetState
     XenBusGrantAccess,              // XenBusIo.GrantAccess
     XenBusGrantEndAccess,           // XenBusIo.GrantEndAccess
     XenBusEventChannelAllocate,     // XenBusIo.EventChannelAllocate
     XenBusEventChannelNotify,       // XenBusIo.EventChannelNotify
     XenBusEventChannelClose,        // XenBusIo.EventChannelClose
     XenBusRegisterWatch,            // XenBusIo.RegisterWatch
     XenBusRegisterWatchBackend,     // XenBusIo.RegisterWatchBackend
     XenBusUnregisterWatch,          // XenBusIo.UnregisterWatch
     XenBusWaitForWatch,             // XenBusIo.WaitForWatch

     NULL,                           // XenBusIo.Type
     0,                              // XenBusIo.DeviceId
     NULL,                           // XenBusIo.Node
     NULL,                           // XenBusIo.Backend
   },

   NULL,                             // Dev
   NULL                              // DevicePath
 };
	/** @file
	XenBus Bus driver implemtation.

	This file implement the necessary to discover and enumerate Xen PV devices
	through XenStore.

	Copyright (C) 2010 Spectra Logic Corporation
	Copyright (C) 2008 Doug Rabson
	Copyright (C) 2005 Rusty Russell, IBM Corporation
	Copyright (C) 2005 Mike Wray, Hewlett-Packard
	Copyright (C) 2005 XenSource Ltd
	Copyright (C) 2014, Citrix Ltd.

	This file may be distributed separately from the Linux kernel, or
	incorporated into other software packages, subject to the following license:

	Permission is hereby granted, free of charge, to any person obtaining a copy
	of this source file (the "Software"), to deal in the Software without
	restriction, including without limitation the rights to use, copy, modify,
	merge, publish, distribute, sublicense, and/or sell copies of the Software,
	and to permit persons to whom the Software is furnished to do so, subject to
	the following conditions:

	The above copyright notice and this permission notice shall be included in
	all copies or substantial portions of the Software.

	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
	FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
	IN THE SOFTWARE.
	**/

	#include <Library/PrintLib.h>

	#include "XenBus.h"
	#include "GrantTable.h"
	#include "XenStore.h"
	#include "EventChannel.h"

	#include <IndustryStandard/Xen/io/xenbus.h>

	STATIC XENBUS_PRIVATE_DATA gXenBusPrivateData;

	STATIC XENBUS_DEVICE_PATH gXenBusDevicePathTemplate = {
	{ // Vendor
	{ // Vendor.Header
	HARDWARE_DEVICE_PATH, // Vendor.Header.Type
	HW_VENDOR_DP, // Vendor.Header.SubType
	{
	(UINT8) (sizeof (XENBUS_DEVICE_PATH)), // Vendor.Header.Length[0]
	(UINT8) (sizeof (XENBUS_DEVICE_PATH) >> 8), // Vendor.Header.Length[1]
	}
	},
	XENBUS_PROTOCOL_GUID, // Vendor.Guid
	},
	0, // Type
	0 // DeviceId
	};


	/**
	Search our internal record of configured devices (not the XenStore) to
	determine if the XenBus device indicated by Node is known to the system.

	@param Dev The XENBUS_DEVICE instance to search for device children.
	@param Node The XenStore node path for the device to find.

	@return The XENBUS_PRIVATE_DATA of the found device if any, or NULL.
	*/
	STATIC
	XENBUS_PRIVATE_DATA *
	XenBusDeviceInitialized (
	IN XENBUS_DEVICE *Dev,
	IN CONST CHAR8 *Node
	)
	{
	LIST_ENTRY *Entry;
	XENBUS_PRIVATE_DATA *Child;
	XENBUS_PRIVATE_DATA *Result;

	if (IsListEmpty (&Dev->ChildList)) {
	return NULL;
	}

	Result = NULL;
	for (Entry = GetFirstNode (&Dev->ChildList);
	!IsNodeAtEnd (&Dev->ChildList, Entry);
	Entry = GetNextNode (&Dev->ChildList, Entry)) {
	Child = XENBUS_PRIVATE_DATA_FROM_LINK (Entry);
	if (!AsciiStrCmp (Child->XenBusIo.Node, Node)) {
	Result = Child;
	break;
	}
	}

	return (Result);
	}

	STATIC
	XenbusState
	XenBusReadDriverState (
	IN CONST CHAR8 *Path
	)
	{
	XenbusState State;
	CHAR8 *Ptr = NULL;
	XENSTORE_STATUS Status;

	Status = XenStoreRead (XST_NIL, Path, "state", NULL, (VOID **)&Ptr);
	if (Status != XENSTORE_STATUS_SUCCESS) {
	State = XenbusStateClosed;
	} else {
	State = AsciiStrDecimalToUintn (Ptr);
	}

	if (Ptr != NULL) {
	FreePool (Ptr);
	}

	return State;
	}

	//
	// Callers should ensure that they are only one calling XenBusAddDevice.
	//
	STATIC
	EFI_STATUS
	XenBusAddDevice (
	XENBUS_DEVICE *Dev,
	CONST CHAR8 *Type,
	CONST CHAR8 *Id)
	{
	CHAR8 DevicePath[XENSTORE_ABS_PATH_MAX];
	XENSTORE_STATUS StatusXenStore;
	XENBUS_PRIVATE_DATA *Private;
	EFI_STATUS Status;
	XENBUS_DEVICE_PATH *TempXenBusPath;
	VOID *ChildXenIo;

	AsciiSPrint (DevicePath, sizeof (DevicePath),
	"device/%a/%a", Type, Id);

	if (XenStorePathExists (XST_NIL, DevicePath, "")) {
	XENBUS_PRIVATE_DATA *Child;
	enum xenbus_state State;
	CHAR8 *BackendPath;

	Child = XenBusDeviceInitialized (Dev, DevicePath);
	if (Child != NULL) {
	/*
	* We are already tracking this node
	*/
	Status = EFI_SUCCESS;
	goto out;
	}

	State = XenBusReadDriverState (DevicePath);
	if (State != XenbusStateInitialising) {
	/*
	* Device is not new, so ignore it. This can
	* happen if a device is going away after
	* switching to Closed.
	*/
	DEBUG ((EFI_D_INFO, "XenBus: Device %a ignored. "
	"State %d\n", DevicePath, State));
	Status = EFI_SUCCESS;
	goto out;
	}

	StatusXenStore = XenStoreRead (XST_NIL, DevicePath, "backend",
	NULL, (VOID **) &BackendPath);
	if (StatusXenStore != XENSTORE_STATUS_SUCCESS) {
	DEBUG ((EFI_D_ERROR, "xenbus: %a no backend path.\n", DevicePath));
	Status = EFI_NOT_FOUND;
	goto out;
	}

	Private = AllocateCopyPool (sizeof (*Private), &gXenBusPrivateData);
	Private->XenBusIo.Type = AsciiStrDup (Type);
	Private->XenBusIo.Node = AsciiStrDup (DevicePath);
	Private->XenBusIo.Backend = BackendPath;
	Private->XenBusIo.DeviceId = (UINT16)AsciiStrDecimalToUintn (Id);
	Private->Dev = Dev;

	TempXenBusPath = AllocateCopyPool (sizeof (XENBUS_DEVICE_PATH),
	&gXenBusDevicePathTemplate);
	if (!AsciiStrCmp (Private->XenBusIo.Type, "vbd")) {
	TempXenBusPath->Type = XENBUS_DEVICE_PATH_TYPE_VBD;
	}
	TempXenBusPath->DeviceId = Private->XenBusIo.DeviceId;
	Private->DevicePath = (XENBUS_DEVICE_PATH *)AppendDevicePathNode (
	Dev->DevicePath,
	&TempXenBusPath->Vendor.Header);
	FreePool (TempXenBusPath);

	InsertTailList (&Dev->ChildList, &Private->Link);

	Status = gBS->InstallMultipleProtocolInterfaces (
	&Private->Handle,
	&gEfiDevicePathProtocolGuid, Private->DevicePath,
	&gXenBusProtocolGuid, &Private->XenBusIo,
	NULL);
	if (EFI_ERROR (Status)) {
	goto ErrorInstallProtocol;
	}

	Status = gBS->OpenProtocol (Dev->ControllerHandle,
	&gXenIoProtocolGuid,
	&ChildXenIo, Dev->This->DriverBindingHandle,
	Private->Handle,
	EFI_OPEN_PROTOCOL_BY_CHILD_CONTROLLER);
	if (EFI_ERROR (Status)) {
	DEBUG ((EFI_D_ERROR, "open by child controller fail (%r)\n",
	Status));
	goto ErrorOpenProtocolByChild;
	}
	} else {
	DEBUG ((EFI_D_ERROR, "XenBus: does not exist: %a\n", DevicePath));
	Status = EFI_NOT_FOUND;
	}

	return Status;

	ErrorOpenProtocolByChild:
	gBS->UninstallMultipleProtocolInterfaces (
	&Private->Handle,
	&gEfiDevicePathProtocolGuid, Private->DevicePath,
	&gXenBusProtocolGuid, &Private->XenBusIo,
	NULL);
	ErrorInstallProtocol:
	RemoveEntryList (&Private->Link);
	FreePool (Private->DevicePath);
	FreePool ((VOID *) Private->XenBusIo.Backend);
	FreePool ((VOID *) Private->XenBusIo.Node);
	FreePool ((VOID *) Private->XenBusIo.Type);
	FreePool (Private);
	out:
	return Status;
	}

	/**
	Enumerate all devices of the given type on this bus.

	@param Dev A XENBUS_DEVICE instance.
	@param Type String indicating the device sub-tree (e.g. "vfb", "vif")
	to enumerate.

	Devices that are found are been initialize via XenBusAddDevice ().
	XenBusAddDevice () ignores duplicate detects and ignores duplicate devices,
	so it can be called unconditionally for any device found in the XenStore.
	*/
	STATIC
	VOID
	XenBusEnumerateDeviceType (
	XENBUS_DEVICE *Dev,
	CONST CHAR8 *Type
	)
	{
	CONST CHAR8 **Directory;
	UINTN Index;
	UINT32 Count;
	XENSTORE_STATUS Status;

	Status = XenStoreListDirectory (XST_NIL,
	"device", Type,
	&Count, &Directory);
	if (Status != XENSTORE_STATUS_SUCCESS) {
	return;
	}
	for (Index = 0; Index < Count; Index++) {
	XenBusAddDevice (Dev, Type, Directory[Index]);
	}

	FreePool ((VOID*)Directory);
	}


	/**
	Enumerate the devices on a XenBus bus and install a XenBus Protocol instance.

	Caller should ensure that it is the only one to call this function. This
	function cannot be called concurrently.

	@param Dev A XENBUS_DEVICE instance.

	@return On success, XENSTORE_STATUS_SUCCESS. Otherwise an errno value
	indicating the type of failure.
	*/
	XENSTORE_STATUS
	XenBusEnumerateBus (
	XENBUS_DEVICE *Dev
	)
	{
	CONST CHAR8 **Types;
	UINTN Index;
	UINT32 Count;
	XENSTORE_STATUS Status;

	Status = XenStoreListDirectory (XST_NIL,
	"device", "",
	&Count, &Types);
	if (Status != XENSTORE_STATUS_SUCCESS) {
	return Status;
	}

	for (Index = 0; Index < Count; Index++) {
	XenBusEnumerateDeviceType (Dev, Types[Index]);
	}

	FreePool ((VOID*)Types);

	return XENSTORE_STATUS_SUCCESS;
	}

	STATIC
	XENSTORE_STATUS
	EFIAPI
	XenBusSetState (
	IN XENBUS_PROTOCOL *This,
	IN CONST XENSTORE_TRANSACTION *Transaction,
	IN enum xenbus_state NewState
	)
	{
	enum xenbus_state CurrentState;
	XENSTORE_STATUS Status;
	CHAR8 *Temp;

	DEBUG ((EFI_D_INFO, "XenBus: Set state to %d\n", NewState));

	Status = XenStoreRead (Transaction, This->Node, "state", NULL, (VOID **)&Temp);
	if (Status != XENSTORE_STATUS_SUCCESS) {
	goto Out;
	}
	CurrentState = AsciiStrDecimalToUintn (Temp);
	FreePool (Temp);
	if (CurrentState == NewState) {
	goto Out;
	}

	do {
	Status = XenStoreSPrint (Transaction, This->Node, "state", "%d", NewState);
	} while (Status == XENSTORE_STATUS_EAGAIN);
	if (Status != XENSTORE_STATUS_SUCCESS) {
	DEBUG ((EFI_D_ERROR, "XenBus: failed to write new state\n"));
	goto Out;
	}
	DEBUG ((EFI_D_INFO, "XenBus: Set state to %d, done\n", NewState));

	Out:
	return Status;
	}

	STATIC XENBUS_PRIVATE_DATA gXenBusPrivateData = {
	XENBUS_PRIVATE_DATA_SIGNATURE, // Signature
	{ NULL, NULL }, // Link
	NULL, // Handle
	{ // XenBusIo
	XenBusXenStoreRead, // XenBusIo.XsRead
	XenBusXenStoreBackendRead, // XenBusIo.XsBackendRead
	XenBusXenStoreSPrint, // XenBusIo.XsPrintf
	XenBusXenStoreRemove, // XenBusIo.XsRemove
	XenBusXenStoreTransactionStart, // XenBusIo.XsTransactionStart
	XenBusXenStoreTransactionEnd, // XenBusIo.XsTransactionEnd
	XenBusSetState, // XenBusIo.SetState
	XenBusGrantAccess, // XenBusIo.GrantAccess
	XenBusGrantEndAccess, // XenBusIo.GrantEndAccess
	XenBusEventChannelAllocate, // XenBusIo.EventChannelAllocate
	XenBusEventChannelNotify, // XenBusIo.EventChannelNotify
	XenBusEventChannelClose, // XenBusIo.EventChannelClose
	XenBusRegisterWatch, // XenBusIo.RegisterWatch
	XenBusRegisterWatchBackend, // XenBusIo.RegisterWatchBackend
	XenBusUnregisterWatch, // XenBusIo.UnregisterWatch
	XenBusWaitForWatch, // XenBusIo.WaitForWatch

	NULL, // XenBusIo.Type
	0, // XenBusIo.DeviceId
	NULL, // XenBusIo.Node
	NULL, // XenBusIo.Backend
	},

	NULL, // Dev
	NULL // DevicePath
	};