[deliverable/linux.git] / drivers / acpi / acpica / tbxfroot.c

/******************************************************************************
 *
 * Module Name: tbxfroot - Find the root ACPI table (RSDT)
 *
 *****************************************************************************/

/*
 * Copyright (C) 2000 - 2016, Intel Corp.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions, and the following disclaimer,
 *    without modification.
 * 2. Redistributions in binary form must reproduce at minimum a disclaimer
 *    substantially similar to the "NO WARRANTY" disclaimer below
 *    ("Disclaimer") and any redistribution must be conditioned upon
 *    including a substantially similar Disclaimer requirement for further
 *    binary redistribution.
 * 3. Neither the names of the above-listed copyright holders nor the names
 *    of any contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * NO WARRANTY
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGES.
 */

#include <acpi/acpi.h>
#include "accommon.h"
#include "actables.h"

#define _COMPONENT          ACPI_TABLES
ACPI_MODULE_NAME("tbxfroot")

/*******************************************************************************
 *
 * FUNCTION:    acpi_tb_get_rsdp_length
 *
 * PARAMETERS:  rsdp                - Pointer to RSDP
 *
 * RETURN:      Table length
 *
 * DESCRIPTION: Get the length of the RSDP
 *
 ******************************************************************************/
u32 acpi_tb_get_rsdp_length(struct acpi_table_rsdp *rsdp)
{

	if (!ACPI_VALIDATE_RSDP_SIG(rsdp->signature)) {

		/* BAD Signature */

		return (0);
	}

	/* "Length" field is available if table version >= 2 */

	if (rsdp->revision >= 2) {
		return (rsdp->length);
	} else {
		return (ACPI_RSDP_CHECKSUM_LENGTH);
	}
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_tb_validate_rsdp
 *
 * PARAMETERS:  rsdp                - Pointer to unvalidated RSDP
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Validate the RSDP (ptr)
 *
 ******************************************************************************/

acpi_status acpi_tb_validate_rsdp(struct acpi_table_rsdp * rsdp)
{

	/*
	 * The signature and checksum must both be correct
	 *
	 * Note: Sometimes there exists more than one RSDP in memory; the valid
	 * RSDP has a valid checksum, all others have an invalid checksum.
	 */
	if (!ACPI_VALIDATE_RSDP_SIG(rsdp->signature)) {

		/* Nope, BAD Signature */

		return (AE_BAD_SIGNATURE);
	}

	/* Check the standard checksum */

	if (acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_CHECKSUM_LENGTH) != 0) {
		return (AE_BAD_CHECKSUM);
	}

	/* Check extended checksum if table version >= 2 */

	if ((rsdp->revision >= 2) &&
	    (acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_XCHECKSUM_LENGTH) != 0)) {
		return (AE_BAD_CHECKSUM);
	}

	return (AE_OK);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_find_root_pointer
 *
 * PARAMETERS:  table_address           - Where the table pointer is returned
 *
 * RETURN:      Status, RSDP physical address
 *
 * DESCRIPTION: Search lower 1Mbyte of memory for the root system descriptor
 *              pointer structure. If it is found, set *RSDP to point to it.
 *
 * NOTE1:       The RSDP must be either in the first 1K of the Extended
 *              BIOS Data Area or between E0000 and FFFFF (From ACPI Spec.)
 *              Only a 32-bit physical address is necessary.
 *
 * NOTE2:       This function is always available, regardless of the
 *              initialization state of the rest of ACPI.
 *
 ******************************************************************************/

acpi_status __init acpi_find_root_pointer(acpi_physical_address * table_address)
{
	u8 *table_ptr;
	u8 *mem_rover;
	u32 physical_address;

	ACPI_FUNCTION_TRACE(acpi_find_root_pointer);

	/* 1a) Get the location of the Extended BIOS Data Area (EBDA) */

	table_ptr = acpi_os_map_memory((acpi_physical_address)
				       ACPI_EBDA_PTR_LOCATION,
				       ACPI_EBDA_PTR_LENGTH);
	if (!table_ptr) {
		ACPI_ERROR((AE_INFO,
			    "Could not map memory at 0x%8.8X for length %u",
			    ACPI_EBDA_PTR_LOCATION, ACPI_EBDA_PTR_LENGTH));

		return_ACPI_STATUS(AE_NO_MEMORY);
	}

	ACPI_MOVE_16_TO_32(&physical_address, table_ptr);

	/* Convert segment part to physical address */

	physical_address <<= 4;
	acpi_os_unmap_memory(table_ptr, ACPI_EBDA_PTR_LENGTH);

	/* EBDA present? */

	if (physical_address > 0x400) {
		/*
		 * 1b) Search EBDA paragraphs (EBDA is required to be a
		 *     minimum of 1K length)
		 */
		table_ptr = acpi_os_map_memory((acpi_physical_address)
					       physical_address,
					       ACPI_EBDA_WINDOW_SIZE);
		if (!table_ptr) {
			ACPI_ERROR((AE_INFO,
				    "Could not map memory at 0x%8.8X for length %u",
				    physical_address, ACPI_EBDA_WINDOW_SIZE));

			return_ACPI_STATUS(AE_NO_MEMORY);
		}

		mem_rover =
		    acpi_tb_scan_memory_for_rsdp(table_ptr,
						 ACPI_EBDA_WINDOW_SIZE);
		acpi_os_unmap_memory(table_ptr, ACPI_EBDA_WINDOW_SIZE);

		if (mem_rover) {

			/* Return the physical address */

			physical_address +=
			    (u32) ACPI_PTR_DIFF(mem_rover, table_ptr);

			*table_address =
			    (acpi_physical_address) physical_address;
			return_ACPI_STATUS(AE_OK);
		}
	}

	/*
	 * 2) Search upper memory: 16-byte boundaries in E0000h-FFFFFh
	 */
	table_ptr = acpi_os_map_memory((acpi_physical_address)
				       ACPI_HI_RSDP_WINDOW_BASE,
				       ACPI_HI_RSDP_WINDOW_SIZE);

	if (!table_ptr) {
		ACPI_ERROR((AE_INFO,
			    "Could not map memory at 0x%8.8X for length %u",
			    ACPI_HI_RSDP_WINDOW_BASE,
			    ACPI_HI_RSDP_WINDOW_SIZE));

		return_ACPI_STATUS(AE_NO_MEMORY);
	}

	mem_rover =
	    acpi_tb_scan_memory_for_rsdp(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE);
	acpi_os_unmap_memory(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE);

	if (mem_rover) {

		/* Return the physical address */

		physical_address = (u32)
		    (ACPI_HI_RSDP_WINDOW_BASE +
		     ACPI_PTR_DIFF(mem_rover, table_ptr));

		*table_address = (acpi_physical_address) physical_address;
		return_ACPI_STATUS(AE_OK);
	}

	/* A valid RSDP was not found */

	ACPI_BIOS_ERROR((AE_INFO, "A valid RSDP was not found"));
	return_ACPI_STATUS(AE_NOT_FOUND);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_tb_scan_memory_for_rsdp
 *
 * PARAMETERS:  start_address       - Starting pointer for search
 *              length              - Maximum length to search
 *
 * RETURN:      Pointer to the RSDP if found, otherwise NULL.
 *
 * DESCRIPTION: Search a block of memory for the RSDP signature
 *
 ******************************************************************************/
u8 *acpi_tb_scan_memory_for_rsdp(u8 *start_address, u32 length)
{
	acpi_status status;
	u8 *mem_rover;
	u8 *end_address;

	ACPI_FUNCTION_TRACE(tb_scan_memory_for_rsdp);

	end_address = start_address + length;

	/* Search from given start address for the requested length */

	for (mem_rover = start_address; mem_rover < end_address;
	     mem_rover += ACPI_RSDP_SCAN_STEP) {

		/* The RSDP signature and checksum must both be correct */

		status =
		    acpi_tb_validate_rsdp(ACPI_CAST_PTR
					  (struct acpi_table_rsdp, mem_rover));
		if (ACPI_SUCCESS(status)) {

			/* Sig and checksum valid, we have found a real RSDP */

			ACPI_DEBUG_PRINT((ACPI_DB_INFO,
					  "RSDP located at physical address %p\n",
					  mem_rover));
			return_PTR(mem_rover);
		}

		/* No sig match or bad checksum, keep searching */
	}

	/* Searched entire block, no RSDP was found */

	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
			  "Searched entire block from %p, valid RSDP was not found\n",
			  start_address));
	return_PTR(NULL);
}
Commit	Line	Data
1da177e4 LT	1	/******************************************************************************
	2	*
	3	* Module Name: tbxfroot - Find the root ACPI table (RSDT)
	4	*
	5	*****************************************************************************/
	6
	7	/*
c8100dc4	8	* Copyright (C) 2000 - 2016, Intel Corp.
1da177e4 LT	9	* All rights reserved.
	10	*
	11	* Redistribution and use in source and binary forms, with or without
	12	* modification, are permitted provided that the following conditions
	13	* are met:
	14	* 1. Redistributions of source code must retain the above copyright
	15	* notice, this list of conditions, and the following disclaimer,
	16	* without modification.
	17	* 2. Redistributions in binary form must reproduce at minimum a disclaimer
	18	* substantially similar to the "NO WARRANTY" disclaimer below
	19	* ("Disclaimer") and any redistribution must be conditioned upon
	20	* including a substantially similar Disclaimer requirement for further
	21	* binary redistribution.
	22	* 3. Neither the names of the above-listed copyright holders nor the names
	23	* of any contributors may be used to endorse or promote products derived
	24	* from this software without specific prior written permission.
	25	*
	26	* Alternatively, this software may be distributed under the terms of the
	27	* GNU General Public License ("GPL") version 2 as published by the Free
	28	* Software Foundation.
	29	*
	30	* NO WARRANTY
	31	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	32	* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	33	* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
	34	* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	35	* HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	36	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	37	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	38	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
	39	* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
	40	* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
	41	* POSSIBILITY OF SUCH DAMAGES.
	42	*/
	43
1da177e4	44	#include <acpi/acpi.h>
e2f7a777 LB	45	#include "accommon.h"
e2f7a777 LB	46	#include "actables.h"
1da177e4	47
1da177e4	48	#define _COMPONENT ACPI_TABLES
4be44fcd	49	ACPI_MODULE_NAME("tbxfroot")
1da177e4	50
f1b69752 LZ	51	/*******************************************************************************
	52	*
	53	* FUNCTION: acpi_tb_get_rsdp_length
	54	*
	55	* PARAMETERS: rsdp - Pointer to RSDP
	56	*
	57	* RETURN: Table length
	58	*
	59	* DESCRIPTION: Get the length of the RSDP
	60	*
	61	******************************************************************************/
	62	u32 acpi_tb_get_rsdp_length(struct acpi_table_rsdp *rsdp)
	63	{
	64
	65	if (!ACPI_VALIDATE_RSDP_SIG(rsdp->signature)) {
	66
	67	/* BAD Signature */
	68
	69	return (0);
	70	}
	71
	72	/* "Length" field is available if table version >= 2 */
	73
	74	if (rsdp->revision >= 2) {
	75	return (rsdp->length);
	76	} else {
	77	return (ACPI_RSDP_CHECKSUM_LENGTH);
	78	}
	79	}
	80
f9f4601f RM	81	/*******************************************************************************
	82	*
	83	* FUNCTION: acpi_tb_validate_rsdp
	84	*
ba494bee	85	* PARAMETERS: rsdp - Pointer to unvalidated RSDP
f9f4601f RM	86	*
	87	* RETURN: Status
	88	*
	89	* DESCRIPTION: Validate the RSDP (ptr)
	90	*
	91	******************************************************************************/
f1b69752 LZ	92
f1b69752 LZ	93	acpi_status acpi_tb_validate_rsdp(struct acpi_table_rsdp * rsdp)
f9f4601f	94	{
f9f4601f RM	95
f9f4601f RM	96	/*
f3d2e786 BM	97	* The signature and checksum must both be correct
	98	*
	99	* Note: Sometimes there exists more than one RSDP in memory; the valid
	100	* RSDP has a valid checksum, all others have an invalid checksum.
f9f4601f	101	*/
cacba865	102	if (!ACPI_VALIDATE_RSDP_SIG(rsdp->signature)) {
52fc0b02	103
f9f4601f RM	104	/* Nope, BAD Signature */
	105
	106	return (AE_BAD_SIGNATURE);
	107	}
	108
	109	/* Check the standard checksum */
	110
f3d2e786	111	if (acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_CHECKSUM_LENGTH) != 0) {
f9f4601f RM	112	return (AE_BAD_CHECKSUM);
	113	}
	114
	115	/* Check extended checksum if table version >= 2 */
	116
	117	if ((rsdp->revision >= 2) &&
f3d2e786	118	(acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_XCHECKSUM_LENGTH) != 0)) {
f9f4601f RM	119	return (AE_BAD_CHECKSUM);
	120	}
	121
	122	return (AE_OK);
	123	}
	124
1da177e4 LT	125	/*******************************************************************************
1da177e4 LT	126	*
239665a3	127	* FUNCTION: acpi_find_root_pointer
1da177e4	128	*
f3d2e786	129	* PARAMETERS: table_address - Where the table pointer is returned
1da177e4	130	*
f3d2e786	131	* RETURN: Status, RSDP physical address
1da177e4	132	*
ba494bee	133	* DESCRIPTION: Search lower 1Mbyte of memory for the root system descriptor
73a3090a	134	* pointer structure. If it is found, set *RSDP to point to it.
1da177e4	135	*
ba494bee	136	* NOTE1: The RSDP must be either in the first 1K of the Extended
f3d2e786 BM	137	* BIOS Data Area or between E0000 and FFFFF (From ACPI Spec.)
f3d2e786 BM	138	* Only a 32-bit physical address is necessary.
1da177e4	139	*
f3d2e786 BM	140	* NOTE2: This function is always available, regardless of the
f3d2e786 BM	141	* initialization state of the rest of ACPI.
1da177e4 LT	142	*
	143	******************************************************************************/
	144
f254e3c5	145	acpi_status __init acpi_find_root_pointer(acpi_physical_address * table_address)
1da177e4	146	{
f3d2e786 BM	147	u8 *table_ptr;
	148	u8 *mem_rover;
	149	u32 physical_address;
1da177e4	150
f3d2e786	151	ACPI_FUNCTION_TRACE(acpi_find_root_pointer);
1da177e4	152
f3d2e786	153	/* 1a) Get the location of the Extended BIOS Data Area (EBDA) */
1da177e4	154
f3d2e786 BM	155	table_ptr = acpi_os_map_memory((acpi_physical_address)
	156	ACPI_EBDA_PTR_LOCATION,
	157	ACPI_EBDA_PTR_LENGTH);
	158	if (!table_ptr) {
	159	ACPI_ERROR((AE_INFO,
f6a22b0b	160	"Could not map memory at 0x%8.8X for length %u",
f3d2e786	161	ACPI_EBDA_PTR_LOCATION, ACPI_EBDA_PTR_LENGTH));
1da177e4	162
4be44fcd	163	return_ACPI_STATUS(AE_NO_MEMORY);
1da177e4 LT	164	}
1da177e4 LT	165
f3d2e786	166	ACPI_MOVE_16_TO_32(&physical_address, table_ptr);
1da177e4	167
f3d2e786	168	/* Convert segment part to physical address */
1da177e4	169
f3d2e786 BM	170	physical_address <<= 4;
f3d2e786 BM	171	acpi_os_unmap_memory(table_ptr, ACPI_EBDA_PTR_LENGTH);
1da177e4	172
f3d2e786	173	/* EBDA present? */
1da177e4	174
f3d2e786	175	if (physical_address > 0x400) {
73459f73	176	/*
f3d2e786	177	* 1b) Search EBDA paragraphs (EBDA is required to be a
ba494bee	178	* minimum of 1K length)
73459f73	179	*/
67a119f9	180	table_ptr = acpi_os_map_memory((acpi_physical_address)
f3d2e786 BM	181	physical_address,
	182	ACPI_EBDA_WINDOW_SIZE);
	183	if (!table_ptr) {
	184	ACPI_ERROR((AE_INFO,
f6a22b0b	185	"Could not map memory at 0x%8.8X for length %u",
f3d2e786	186	physical_address, ACPI_EBDA_WINDOW_SIZE));
1da177e4	187
f3d2e786	188	return_ACPI_STATUS(AE_NO_MEMORY);
1da177e4 LT	189	}
1da177e4 LT	190
f3d2e786 BM	191	mem_rover =
	192	acpi_tb_scan_memory_for_rsdp(table_ptr,
	193	ACPI_EBDA_WINDOW_SIZE);
	194	acpi_os_unmap_memory(table_ptr, ACPI_EBDA_WINDOW_SIZE);
1da177e4	195
f3d2e786	196	if (mem_rover) {
52fc0b02	197
f3d2e786	198	/* Return the physical address */
1da177e4	199
f3d2e786 BM	200	physical_address +=
f3d2e786 BM	201	(u32) ACPI_PTR_DIFF(mem_rover, table_ptr);
1da177e4	202
f254e3c5 LZ	203	*table_address =
f254e3c5 LZ	204	(acpi_physical_address) physical_address;
f3d2e786	205	return_ACPI_STATUS(AE_OK);
1da177e4 LT	206	}
	207	}
	208
f3d2e786 BM	209	/*
	210	* 2) Search upper memory: 16-byte boundaries in E0000h-FFFFFh
	211	*/
	212	table_ptr = acpi_os_map_memory((acpi_physical_address)
	213	ACPI_HI_RSDP_WINDOW_BASE,
	214	ACPI_HI_RSDP_WINDOW_SIZE);
1da177e4	215
f3d2e786 BM	216	if (!table_ptr) {
f3d2e786 BM	217	ACPI_ERROR((AE_INFO,
f6a22b0b	218	"Could not map memory at 0x%8.8X for length %u",
f3d2e786 BM	219	ACPI_HI_RSDP_WINDOW_BASE,
f3d2e786 BM	220	ACPI_HI_RSDP_WINDOW_SIZE));
1da177e4	221
f3d2e786	222	return_ACPI_STATUS(AE_NO_MEMORY);
88ac00f5	223	}
1da177e4	224
f3d2e786 BM	225	mem_rover =
	226	acpi_tb_scan_memory_for_rsdp(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE);
	227	acpi_os_unmap_memory(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE);
1da177e4	228
f3d2e786	229	if (mem_rover) {
1da177e4	230
f3d2e786	231	/* Return the physical address */
1da177e4	232
f3d2e786 BM	233	physical_address = (u32)
	234	(ACPI_HI_RSDP_WINDOW_BASE +
	235	ACPI_PTR_DIFF(mem_rover, table_ptr));
1da177e4	236
f254e3c5	237	*table_address = (acpi_physical_address) physical_address;
f3d2e786	238	return_ACPI_STATUS(AE_OK);
1da177e4 LT	239	}
1da177e4 LT	240
f3d2e786 BM	241	/* A valid RSDP was not found */
f3d2e786 BM	242
3b3ea775	243	ACPI_BIOS_ERROR((AE_INFO, "A valid RSDP was not found"));
f3d2e786	244	return_ACPI_STATUS(AE_NOT_FOUND);
1da177e4 LT	245	}
1da177e4 LT	246
1da177e4 LT	247	/*******************************************************************************
	248	*
	249	* FUNCTION: acpi_tb_scan_memory_for_rsdp
	250	*
	251	* PARAMETERS: start_address - Starting pointer for search
ba494bee	252	* length - Maximum length to search
1da177e4 LT	253	*
	254	* RETURN: Pointer to the RSDP if found, otherwise NULL.
	255	*
	256	* DESCRIPTION: Search a block of memory for the RSDP signature
	257	*
	258	******************************************************************************/
57987ca2	259	u8 acpi_tb_scan_memory_for_rsdp(u8 start_address, u32 length)
1da177e4	260	{
4be44fcd LB	261	acpi_status status;
	262	u8 *mem_rover;
	263	u8 *end_address;
1da177e4	264
b229cf92	265	ACPI_FUNCTION_TRACE(tb_scan_memory_for_rsdp);
1da177e4 LT	266
	267	end_address = start_address + length;
	268
	269	/* Search from given start address for the requested length */
	270
	271	for (mem_rover = start_address; mem_rover < end_address;
4be44fcd	272	mem_rover += ACPI_RSDP_SCAN_STEP) {
52fc0b02	273
f9f4601f	274	/* The RSDP signature and checksum must both be correct */
1da177e4	275
4be44fcd LB	276	status =
4be44fcd LB	277	acpi_tb_validate_rsdp(ACPI_CAST_PTR
f3d2e786	278	(struct acpi_table_rsdp, mem_rover));
4be44fcd	279	if (ACPI_SUCCESS(status)) {
52fc0b02	280
f9f4601f	281	/* Sig and checksum valid, we have found a real RSDP */
1da177e4	282
4be44fcd LB	283	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
	284	"RSDP located at physical address %p\n",
	285	mem_rover));
	286	return_PTR(mem_rover);
1da177e4 LT	287	}
1da177e4 LT	288
f9f4601f	289	/* No sig match or bad checksum, keep searching */
1da177e4 LT	290	}
	291
	292	/* Searched entire block, no RSDP was found */
	293
4be44fcd LB	294	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
	295	"Searched entire block from %p, valid RSDP was not found\n",
	296	start_address));
	297	return_PTR(NULL);
1da177e4	298	}