[mirror_edk2.git] / OvmfPkg / Library / QemuNewBootOrderLib / ExtraRootBusMap.c

/** @file\r
  Map positions of extra PCI root buses to bus numbers.\r
\r
  Copyright (C) 2015, Red Hat, Inc.\r
\r
  This program and the accompanying materials are licensed and made available\r
  under the terms and conditions of the BSD License which accompanies this\r
  distribution.  The full text of the license may be found at\r
  http://opensource.org/licenses/bsd-license.php\r
\r
  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT\r
  WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
**/\r
\r
#include <Library/DebugLib.h>\r
#include <Library/DevicePathLib.h>\r
#include <Library/MemoryAllocationLib.h>\r
#include <Library/OrderedCollectionLib.h>\r
#include <Library/UefiBootServicesTableLib.h>\r
#include <Protocol/DevicePath.h>\r
#include <Protocol/PciRootBridgeIo.h>\r
\r
#include "ExtraRootBusMap.h"\r
\r
//\r
// The BusNumbers field is an array with Count elements. The elements increase\r
// strictry monotonically. Zero is not an element (because the zero bus number\r
// belongs to the "main" root bus, never to an extra root bus). Offset N in the\r
// array maps the extra root bus with position (N+1) to its bus number (because\r
// the root bus with position 0 is always the main root bus, therefore we don't\r
// store it).\r
//\r
// If there are no extra root buses in the system, then Count is 0, and\r
// BusNumbers is NULL.\r
//\r
struct EXTRA_ROOT_BUS_MAP_STRUCT {\r
  UINT32 *BusNumbers;\r
  UINTN  Count;\r
};\r
\r
\r
/**\r
  An ORDERED_COLLECTION_USER_COMPARE function that compares root bridge\r
  protocol device paths based on UID.\r
\r
  @param[in] UserStruct1  Pointer to the first ACPI_HID_DEVICE_PATH.\r
\r
  @param[in] UserStruct2  Pointer to the second ACPI_HID_DEVICE_PATH.\r
\r
  @retval <0  If UserStruct1 compares less than UserStruct2.\r
\r
  @retval  0  If UserStruct1 compares equal to UserStruct2.\r
\r
  @retval >0  If UserStruct1 compares greater than UserStruct2.\r
**/\r
STATIC\r
INTN\r
EFIAPI\r
RootBridgePathCompare (\r
  IN CONST VOID *UserStruct1,\r
  IN CONST VOID *UserStruct2\r
  )\r
{\r
  CONST ACPI_HID_DEVICE_PATH *Acpi1;\r
  CONST ACPI_HID_DEVICE_PATH *Acpi2;\r
\r
  Acpi1 = UserStruct1;\r
  Acpi2 = UserStruct2;\r
\r
  return Acpi1->UID < Acpi2->UID ? -1 :\r
         Acpi1->UID > Acpi2->UID ?  1 :\r
         0;\r
}\r
\r
\r
/**\r
  An ORDERED_COLLECTION_KEY_COMPARE function that compares a root bridge\r
  protocol device path against a UID.\r
\r
  @param[in] StandaloneKey  Pointer to the bare UINT32 UID.\r
\r
  @param[in] UserStruct     Pointer to the ACPI_HID_DEVICE_PATH with the\r
                            embedded UINT32 UID.\r
\r
  @retval <0  If StandaloneKey compares less than UserStruct's key.\r
\r
  @retval  0  If StandaloneKey compares equal to UserStruct's key.\r
\r
  @retval >0  If StandaloneKey compares greater than UserStruct's key.\r
**/\r
STATIC\r
INTN\r
EFIAPI\r
RootBridgePathKeyCompare (\r
  IN CONST VOID *StandaloneKey,\r
  IN CONST VOID *UserStruct\r
  )\r
{\r
  CONST UINT32               *Uid;\r
  CONST ACPI_HID_DEVICE_PATH *Acpi;\r
\r
  Uid  = StandaloneKey;\r
  Acpi = UserStruct;\r
\r
  return *Uid < Acpi->UID ? -1 :\r
         *Uid > Acpi->UID ?  1 :\r
         0;\r
}\r
\r
\r
/**\r
  Create a structure that maps the relative positions of PCI root buses to bus\r
  numbers.\r
\r
  In the "bootorder" fw_cfg file, QEMU refers to extra PCI root buses by their\r
  positions, in relative root bus number order, not by their actual PCI bus\r
  numbers. The ACPI HID device path nodes however that are associated with\r
  PciRootBridgeIo protocol instances in the system have their UID fields set to\r
  the bus numbers. Create a map that gives, for each extra PCI root bus's\r
  position (ie. "serial number") its actual PCI bus number.\r
\r
  @param[out] ExtraRootBusMap  The data structure implementing the map.\r
\r
  @retval EFI_SUCCESS           ExtraRootBusMap has been populated.\r
\r
  @retval EFI_OUT_OF_RESOURCES  Memory allocation failed.\r
\r
  @retval EFI_ALREADY_STARTED   A duplicate root bus number has been found in\r
                                the system. (This should never happen.)\r
\r
  @return                       Error codes returned by\r
                                gBS->LocateHandleBuffer() and\r
                                gBS->HandleProtocol().\r
\r
**/\r
EFI_STATUS\r
CreateExtraRootBusMap (\r
  OUT EXTRA_ROOT_BUS_MAP **ExtraRootBusMap\r
  )\r
{\r
  EFI_STATUS               Status;\r
  UINTN                    NumHandles;\r
  EFI_HANDLE               *Handles;\r
  ORDERED_COLLECTION       *Collection;\r
  EXTRA_ROOT_BUS_MAP       *Map;\r
  UINTN                    Idx;\r
  ORDERED_COLLECTION_ENTRY *Entry, *Entry2;\r
\r
  //\r
  // Handles and Collection are temporary / helper variables, while in Map we\r
  // build the return value.\r
  //\r
\r
  Status = gBS->LocateHandleBuffer (ByProtocol,\r
                  &gEfiPciRootBridgeIoProtocolGuid, NULL /* SearchKey */,\r
                  &NumHandles, &Handles);\r
  if (EFI_ERROR (Status))  {\r
    return Status;\r
  }\r
\r
  Collection = OrderedCollectionInit (RootBridgePathCompare,\r
                 RootBridgePathKeyCompare);\r
  if (Collection == NULL) {\r
    Status = EFI_OUT_OF_RESOURCES;\r
    goto FreeHandles;\r
  }\r
\r
  Map = AllocateZeroPool (sizeof *Map);\r
  if (Map == NULL) {\r
    Status = EFI_OUT_OF_RESOURCES;\r
    goto FreeCollection;\r
  }\r
\r
  //\r
  // Collect the ACPI device path protocols of the root bridges.\r
  //\r
  for (Idx = 0; Idx < NumHandles; ++Idx) {\r
    EFI_DEVICE_PATH_PROTOCOL *DevicePath;\r
\r
    Status = gBS->HandleProtocol (Handles[Idx], &gEfiDevicePathProtocolGuid,\r
                    (VOID**)&DevicePath);\r
    if (EFI_ERROR (Status)) {\r
      goto FreeMap;\r
    }\r
\r
    //\r
    // Examine if the device path is an ACPI HID one, and if so, if UID is\r
    // nonzero (ie. the root bridge that the bus number belongs to is "extra",\r
    // not the main one). In that case, link the device path into Collection.\r
    //\r
    if (DevicePathType (DevicePath) == ACPI_DEVICE_PATH &&\r
        DevicePathSubType (DevicePath) == ACPI_DP &&\r
        ((ACPI_HID_DEVICE_PATH *)DevicePath)->HID == EISA_PNP_ID(0x0A03) &&\r
        ((ACPI_HID_DEVICE_PATH *)DevicePath)->UID > 0) {\r
      Status = OrderedCollectionInsert (Collection, NULL, DevicePath);\r
      if (EFI_ERROR (Status)) {\r
        goto FreeMap;\r
      }\r
      ++Map->Count;\r
    }\r
  }\r
\r
  if (Map->Count > 0) {\r
    //\r
    // At least one extra PCI root bus exists.\r
    //\r
    Map->BusNumbers = AllocatePool (Map->Count * sizeof *Map->BusNumbers);\r
    if (Map->BusNumbers == NULL) {\r
      Status = EFI_OUT_OF_RESOURCES;\r
      goto FreeMap;\r
    }\r
  }\r
\r
  //\r
  // Now collect the bus numbers of the extra PCI root buses into Map.\r
  //\r
  Idx = 0;\r
  Entry = OrderedCollectionMin (Collection);\r
  while (Idx < Map->Count) {\r
    ACPI_HID_DEVICE_PATH *Acpi;\r
\r
    ASSERT (Entry != NULL);\r
    Acpi = OrderedCollectionUserStruct (Entry);\r
    Map->BusNumbers[Idx] = Acpi->UID;\r
    DEBUG ((EFI_D_VERBOSE,\r
      "%a: extra bus position 0x%Lx maps to bus number (UID) 0x%x\n",\r
      __FUNCTION__, (UINT64)(Idx + 1), Acpi->UID));\r
    ++Idx;\r
    Entry = OrderedCollectionNext (Entry);\r
  }\r
  ASSERT (Entry == NULL);\r
\r
  *ExtraRootBusMap = Map;\r
  Status = EFI_SUCCESS;\r
\r
  //\r
  // Fall through in order to release temporaries.\r
  //\r
\r
FreeMap:\r
  if (EFI_ERROR (Status)) {\r
    if (Map->BusNumbers != NULL) {\r
      FreePool (Map->BusNumbers);\r
    }\r
    FreePool (Map);\r
  }\r
\r
FreeCollection:\r
  for (Entry = OrderedCollectionMin (Collection); Entry != NULL;\r
       Entry = Entry2) {\r
    Entry2 = OrderedCollectionNext (Entry);\r
    OrderedCollectionDelete (Collection, Entry, NULL);\r
  }\r
  OrderedCollectionUninit (Collection);\r
\r
FreeHandles:\r
  FreePool (Handles);\r
\r
  return Status;\r
}\r
\r
\r
/**\r
  Release a map created with CreateExtraRootBusMap().\r
\r
  @param[in] ExtraRootBusMap  The map to release.\r
*/\r
VOID\r
DestroyExtraRootBusMap (\r
  IN EXTRA_ROOT_BUS_MAP *ExtraRootBusMap\r
  )\r
{\r
  if (ExtraRootBusMap->BusNumbers != NULL) {\r
    FreePool (ExtraRootBusMap->BusNumbers);\r
  }\r
  FreePool (ExtraRootBusMap);\r
}\r
\r
/**\r
  Map the position (serial number) of an extra PCI root bus to its bus number.\r
\r
  @param[in]  ExtraRootBusMap  The map created with CreateExtraRootBusMap();\r
\r
  @param[in]  RootBusPos       The extra PCI root bus position to map.\r
\r
  @param[out] RootBusNr        The bus number belonging to the extra PCI root\r
                               bus identified by RootBusPos.\r
\r
  @retval EFI_INVALID_PARAMETER  RootBusPos is zero. The zero position\r
                                 identifies the main root bus, whose bus number\r
                                 is always zero, and is therefore never\r
                                 maintained in ExtraRootBusMap.\r
\r
  @retval EFI_NOT_FOUND          RootBusPos is not found in ExtraRootBusMap.\r
\r
  @retval EFI_SUCCESS            Mapping successful.\r
**/\r
EFI_STATUS\r
MapRootBusPosToBusNr (\r
  IN  CONST EXTRA_ROOT_BUS_MAP *ExtraRootBusMap,\r
  IN  UINT64                   RootBusPos,\r
  OUT UINT32                   *RootBusNr\r
  )\r
{\r
  if (RootBusPos == 0) {\r
    return EFI_INVALID_PARAMETER;\r
  }\r
  if (RootBusPos > ExtraRootBusMap->Count) {\r
    return EFI_NOT_FOUND;\r
  }\r
  *RootBusNr = ExtraRootBusMap->BusNumbers[RootBusPos - 1];\r
  return EFI_SUCCESS;\r
}\r
Commit	Line	Data
6b40e66a RN	1	/** @file\r
	2	Map positions of extra PCI root buses to bus numbers.\r
	3	\r
	4	Copyright (C) 2015, Red Hat, Inc.\r
	5	\r
	6	This program and the accompanying materials are licensed and made available\r
	7	under the terms and conditions of the BSD License which accompanies this\r
	8	distribution. The full text of the license may be found at\r
	9	http://opensource.org/licenses/bsd-license.php\r
	10	\r
	11	THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT\r
	12	WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
	13	**/\r
	14	\r
	15	#include <Library/DebugLib.h>\r
	16	#include <Library/DevicePathLib.h>\r
	17	#include <Library/MemoryAllocationLib.h>\r
	18	#include <Library/OrderedCollectionLib.h>\r
	19	#include <Library/UefiBootServicesTableLib.h>\r
	20	#include <Protocol/DevicePath.h>\r
	21	#include <Protocol/PciRootBridgeIo.h>\r
	22	\r
	23	#include "ExtraRootBusMap.h"\r
	24	\r
	25	//\r
	26	// The BusNumbers field is an array with Count elements. The elements increase\r
	27	// strictry monotonically. Zero is not an element (because the zero bus number\r
	28	// belongs to the "main" root bus, never to an extra root bus). Offset N in the\r
	29	// array maps the extra root bus with position (N+1) to its bus number (because\r
	30	// the root bus with position 0 is always the main root bus, therefore we don't\r
	31	// store it).\r
	32	//\r
	33	// If there are no extra root buses in the system, then Count is 0, and\r
	34	// BusNumbers is NULL.\r
	35	//\r
	36	struct EXTRA_ROOT_BUS_MAP_STRUCT {\r
	37	UINT32 *BusNumbers;\r
	38	UINTN Count;\r
	39	};\r
	40	\r
	41	\r
	42	/**\r
	43	An ORDERED_COLLECTION_USER_COMPARE function that compares root bridge\r
	44	protocol device paths based on UID.\r
	45	\r
	46	@param[in] UserStruct1 Pointer to the first ACPI_HID_DEVICE_PATH.\r
	47	\r
	48	@param[in] UserStruct2 Pointer to the second ACPI_HID_DEVICE_PATH.\r
	49	\r
	50	@retval <0 If UserStruct1 compares less than UserStruct2.\r
	51	\r
	52	@retval 0 If UserStruct1 compares equal to UserStruct2.\r
	53	\r
	54	@retval >0 If UserStruct1 compares greater than UserStruct2.\r
	55	**/\r
	56	STATIC\r
	57	INTN\r
	58	EFIAPI\r
	59	RootBridgePathCompare (\r
	60	IN CONST VOID *UserStruct1,\r
	61	IN CONST VOID *UserStruct2\r
	62	)\r
	63	{\r
	64	CONST ACPI_HID_DEVICE_PATH *Acpi1;\r
65	CONST ACPI_HID_DEVICE_PATH *Acpi2;\r
66	\r
67	Acpi1 = UserStruct1;\r
68	Acpi2 = UserStruct2;\r
69	\r
70	return Acpi1->UID < Acpi2->UID ? -1 :\r
71	Acpi1->UID > Acpi2->UID ? 1 :\r
72	0;\r
73	}\r
74	\r
75	\r
76	/**\r
77	An ORDERED_COLLECTION_KEY_COMPARE function that compares a root bridge\r
78	protocol device path against a UID.\r
79	\r
80	@param[in] StandaloneKey Pointer to the bare UINT32 UID.\r
81	\r
82	@param[in] UserStruct Pointer to the ACPI_HID_DEVICE_PATH with the\r
83	embedded UINT32 UID.\r
84	\r
85	@retval <0 If StandaloneKey compares less than UserStruct's key.\r
86	\r
87	@retval 0 If StandaloneKey compares equal to UserStruct's key.\r
88	\r
89	@retval >0 If StandaloneKey compares greater than UserStruct's key.\r
90	**/\r
91	STATIC\r
92	INTN\r
93	EFIAPI\r
94	RootBridgePathKeyCompare (\r
95	IN CONST VOID *StandaloneKey,\r
96	IN CONST VOID *UserStruct\r
97	)\r
98	{\r
99	CONST UINT32 *Uid;\r
100	CONST ACPI_HID_DEVICE_PATH *Acpi;\r
101	\r
102	Uid = StandaloneKey;\r
103	Acpi = UserStruct;\r
104	\r
105	return *Uid < Acpi->UID ? -1 :\r
106	*Uid > Acpi->UID ? 1 :\r
107	0;\r
108	}\r
109	\r
110	\r
111	/**\r
112	Create a structure that maps the relative positions of PCI root buses to bus\r
113	numbers.\r
114	\r
115	In the "bootorder" fw_cfg file, QEMU refers to extra PCI root buses by their\r
116	positions, in relative root bus number order, not by their actual PCI bus\r
117	numbers. The ACPI HID device path nodes however that are associated with\r
118	PciRootBridgeIo protocol instances in the system have their UID fields set to\r
119	the bus numbers. Create a map that gives, for each extra PCI root bus's\r
120	position (ie. "serial number") its actual PCI bus number.\r
121	\r
122	@param[out] ExtraRootBusMap The data structure implementing the map.\r
123	\r
124	@retval EFI_SUCCESS ExtraRootBusMap has been populated.\r
125	\r
126	@retval EFI_OUT_OF_RESOURCES Memory allocation failed.\r
127	\r
128	@retval EFI_ALREADY_STARTED A duplicate root bus number has been found in\r
129	the system. (This should never happen.)\r
130	\r
131	@return Error codes returned by\r
132	gBS->LocateHandleBuffer() and\r
133	gBS->HandleProtocol().\r
134	\r
135	**/\r
136	EFI_STATUS\r
137	CreateExtraRootBusMap (\r
138	OUT EXTRA_ROOT_BUS_MAP **ExtraRootBusMap\r
139	)\r
140	{\r
141	EFI_STATUS Status;\r
142	UINTN NumHandles;\r
143	EFI_HANDLE *Handles;\r
144	ORDERED_COLLECTION *Collection;\r
145	EXTRA_ROOT_BUS_MAP *Map;\r
146	UINTN Idx;\r
147	ORDERED_COLLECTION_ENTRY Entry, Entry2;\r
148	\r
149	//\r
150	// Handles and Collection are temporary / helper variables, while in Map we\r
151	// build the return value.\r
152	//\r
153	\r
154	Status = gBS->LocateHandleBuffer (ByProtocol,\r
155	&gEfiPciRootBridgeIoProtocolGuid, NULL /* SearchKey */,\r
156	&NumHandles, &Handles);\r
157	if (EFI_ERROR (Status)) {\r
158	return Status;\r
159	}\r
160	\r
161	Collection = OrderedCollectionInit (RootBridgePathCompare,\r
162	RootBridgePathKeyCompare);\r
163	if (Collection == NULL) {\r
164	Status = EFI_OUT_OF_RESOURCES;\r
165	goto FreeHandles;\r
166	}\r
167	\r
168	Map = AllocateZeroPool (sizeof *Map);\r
169	if (Map == NULL) {\r
170	Status = EFI_OUT_OF_RESOURCES;\r
171	goto FreeCollection;\r
172	}\r
173	\r
174	//\r
175	// Collect the ACPI device path protocols of the root bridges.\r
176	//\r
177	for (Idx = 0; Idx < NumHandles; ++Idx) {\r
178	EFI_DEVICE_PATH_PROTOCOL *DevicePath;\r
179	\r
180	Status = gBS->HandleProtocol (Handles[Idx], &gEfiDevicePathProtocolGuid,\r
181	(VOID**)&DevicePath);\r
182	if (EFI_ERROR (Status)) {\r
183	goto FreeMap;\r
184	}\r
185	\r
186	//\r
187	// Examine if the device path is an ACPI HID one, and if so, if UID is\r
188	// nonzero (ie. the root bridge that the bus number belongs to is "extra",\r
189	// not the main one). In that case, link the device path into Collection.\r
190	//\r
191	if (DevicePathType (DevicePath) == ACPI_DEVICE_PATH &&\r
192	DevicePathSubType (DevicePath) == ACPI_DP &&\r
193	((ACPI_HID_DEVICE_PATH *)DevicePath)->HID == EISA_PNP_ID(0x0A03) &&\r
194	((ACPI_HID_DEVICE_PATH *)DevicePath)->UID > 0) {\r
195	Status = OrderedCollectionInsert (Collection, NULL, DevicePath);\r
196	if (EFI_ERROR (Status)) {\r
197	goto FreeMap;\r
198	}\r
199	++Map->Count;\r
200	}\r
201	}\r
202	\r
203	if (Map->Count > 0) {\r
204	//\r
205	// At least one extra PCI root bus exists.\r
206	//\r
207	Map->BusNumbers = AllocatePool (Map->Count * sizeof *Map->BusNumbers);\r
208	if (Map->BusNumbers == NULL) {\r
209	Status = EFI_OUT_OF_RESOURCES;\r
210	goto FreeMap;\r
211	}\r
212	}\r
213	\r
214	//\r
215	// Now collect the bus numbers of the extra PCI root buses into Map.\r
216	//\r
217	Idx = 0;\r
218	Entry = OrderedCollectionMin (Collection);\r
219	while (Idx < Map->Count) {\r
220	ACPI_HID_DEVICE_PATH *Acpi;\r
221	\r
222	ASSERT (Entry != NULL);\r
223	Acpi = OrderedCollectionUserStruct (Entry);\r
224	Map->BusNumbers[Idx] = Acpi->UID;\r
225	DEBUG ((EFI_D_VERBOSE,\r
226	"%a: extra bus position 0x%Lx maps to bus number (UID) 0x%x\n",\r
227	__FUNCTION__, (UINT64)(Idx + 1), Acpi->UID));\r
228	++Idx;\r
229	Entry = OrderedCollectionNext (Entry);\r
230	}\r
231	ASSERT (Entry == NULL);\r
232	\r
233	*ExtraRootBusMap = Map;\r
234	Status = EFI_SUCCESS;\r
235	\r
236	//\r
237	// Fall through in order to release temporaries.\r
238	//\r
239	\r
240	FreeMap:\r
241	if (EFI_ERROR (Status)) {\r
242	if (Map->BusNumbers != NULL) {\r
243	FreePool (Map->BusNumbers);\r
244	}\r
245	FreePool (Map);\r
246	}\r
247	\r
248	FreeCollection:\r
249	for (Entry = OrderedCollectionMin (Collection); Entry != NULL;\r
250	Entry = Entry2) {\r
251	Entry2 = OrderedCollectionNext (Entry);\r
252	OrderedCollectionDelete (Collection, Entry, NULL);\r
253	}\r
254	OrderedCollectionUninit (Collection);\r
255	\r
256	FreeHandles:\r
257	FreePool (Handles);\r
258	\r
259	return Status;\r
260	}\r
261	\r
262	\r
263	/**\r
264	Release a map created with CreateExtraRootBusMap().\r
265	\r
266	@param[in] ExtraRootBusMap The map to release.\r
267	*/\r
268	VOID\r
269	DestroyExtraRootBusMap (\r
270	IN EXTRA_ROOT_BUS_MAP *ExtraRootBusMap\r
271	)\r
272	{\r
273	if (ExtraRootBusMap->BusNumbers != NULL) {\r
274	FreePool (ExtraRootBusMap->BusNumbers);\r
275	}\r
276	FreePool (ExtraRootBusMap);\r
277	}\r
278	\r
279	/**\r
280	Map the position (serial number) of an extra PCI root bus to its bus number.\r
281	\r
282	@param[in] ExtraRootBusMap The map created with CreateExtraRootBusMap();\r
283	\r
284	@param[in] RootBusPos The extra PCI root bus position to map.\r
285	\r
286	@param[out] RootBusNr The bus number belonging to the extra PCI root\r
287	bus identified by RootBusPos.\r
288	\r
289	@retval EFI_INVALID_PARAMETER RootBusPos is zero. The zero position\r
290	identifies the main root bus, whose bus number\r
291	is always zero, and is therefore never\r
292	maintained in ExtraRootBusMap.\r
293	\r
294	@retval EFI_NOT_FOUND RootBusPos is not found in ExtraRootBusMap.\r
295	\r
296	@retval EFI_SUCCESS Mapping successful.\r
297	**/\r
298	EFI_STATUS\r
299	MapRootBusPosToBusNr (\r
300	IN CONST EXTRA_ROOT_BUS_MAP *ExtraRootBusMap,\r
301	IN UINT64 RootBusPos,\r
302	OUT UINT32 *RootBusNr\r
303	)\r
304	{\r
305	if (RootBusPos == 0) {\r
306	return EFI_INVALID_PARAMETER;\r
307	}\r
308	if (RootBusPos > ExtraRootBusMap->Count) {\r
309	return EFI_NOT_FOUND;\r
310	}\r
311	*RootBusNr = ExtraRootBusMap->BusNumbers[RootBusPos - 1];\r
312	return EFI_SUCCESS;\r
313	}\r