1// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
2/******************************************************************************
3 *
4 * Module Name: tbfadt   - FADT table utilities
5 *
6 * Copyright (C) 2000 - 2023, Intel Corp.
7 *
8 *****************************************************************************/
9
10#include <acpi/acpi.h>
11#include "accommon.h"
12#include "actables.h"
13
14#define _COMPONENT          ACPI_TABLES
15ACPI_MODULE_NAME("tbfadt")
16
17/* Local prototypes */
18static void
19acpi_tb_init_generic_address(struct acpi_generic_address *generic_address,
20			     u8 space_id,
21			     u8 byte_width,
22			     u64 address, const char *register_name, u8 flags);
23
24static void acpi_tb_convert_fadt(void);
25
26static void acpi_tb_setup_fadt_registers(void);
27
28static u64
29acpi_tb_select_address(char *register_name, u32 address32, u64 address64);
30
31/* Table for conversion of FADT to common internal format and FADT validation */
32
33typedef struct acpi_fadt_info {
34	const char *name;
35	u16 address64;
36	u16 address32;
37	u16 length;
38	u8 default_length;
39	u8 flags;
40
41} acpi_fadt_info;
42
43#define ACPI_FADT_OPTIONAL          0
44#define ACPI_FADT_REQUIRED          1
45#define ACPI_FADT_SEPARATE_LENGTH   2
46#define ACPI_FADT_GPE_REGISTER      4
47
48static struct acpi_fadt_info fadt_info_table[] = {
49	{"Pm1aEventBlock",
50	 ACPI_FADT_OFFSET(xpm1a_event_block),
51	 ACPI_FADT_OFFSET(pm1a_event_block),
52	 ACPI_FADT_OFFSET(pm1_event_length),
53	 ACPI_PM1_REGISTER_WIDTH * 2,	/* Enable + Status register */
54	 ACPI_FADT_REQUIRED},
55
56	{"Pm1bEventBlock",
57	 ACPI_FADT_OFFSET(xpm1b_event_block),
58	 ACPI_FADT_OFFSET(pm1b_event_block),
59	 ACPI_FADT_OFFSET(pm1_event_length),
60	 ACPI_PM1_REGISTER_WIDTH * 2,	/* Enable + Status register */
61	 ACPI_FADT_OPTIONAL},
62
63	{"Pm1aControlBlock",
64	 ACPI_FADT_OFFSET(xpm1a_control_block),
65	 ACPI_FADT_OFFSET(pm1a_control_block),
66	 ACPI_FADT_OFFSET(pm1_control_length),
67	 ACPI_PM1_REGISTER_WIDTH,
68	 ACPI_FADT_REQUIRED},
69
70	{"Pm1bControlBlock",
71	 ACPI_FADT_OFFSET(xpm1b_control_block),
72	 ACPI_FADT_OFFSET(pm1b_control_block),
73	 ACPI_FADT_OFFSET(pm1_control_length),
74	 ACPI_PM1_REGISTER_WIDTH,
75	 ACPI_FADT_OPTIONAL},
76
77	{"Pm2ControlBlock",
78	 ACPI_FADT_OFFSET(xpm2_control_block),
79	 ACPI_FADT_OFFSET(pm2_control_block),
80	 ACPI_FADT_OFFSET(pm2_control_length),
81	 ACPI_PM2_REGISTER_WIDTH,
82	 ACPI_FADT_SEPARATE_LENGTH},
83
84	{"PmTimerBlock",
85	 ACPI_FADT_OFFSET(xpm_timer_block),
86	 ACPI_FADT_OFFSET(pm_timer_block),
87	 ACPI_FADT_OFFSET(pm_timer_length),
88	 ACPI_PM_TIMER_WIDTH,
89	 ACPI_FADT_SEPARATE_LENGTH},	/* ACPI 5.0A: Timer is optional */
90
91	{"Gpe0Block",
92	 ACPI_FADT_OFFSET(xgpe0_block),
93	 ACPI_FADT_OFFSET(gpe0_block),
94	 ACPI_FADT_OFFSET(gpe0_block_length),
95	 0,
96	 ACPI_FADT_SEPARATE_LENGTH | ACPI_FADT_GPE_REGISTER},
97
98	{"Gpe1Block",
99	 ACPI_FADT_OFFSET(xgpe1_block),
100	 ACPI_FADT_OFFSET(gpe1_block),
101	 ACPI_FADT_OFFSET(gpe1_block_length),
102	 0,
103	 ACPI_FADT_SEPARATE_LENGTH | ACPI_FADT_GPE_REGISTER}
104};
105
106#define ACPI_FADT_INFO_ENTRIES \
107			(sizeof (fadt_info_table) / sizeof (struct acpi_fadt_info))
108
109/* Table used to split Event Blocks into separate status/enable registers */
110
111typedef struct acpi_fadt_pm_info {
112	struct acpi_generic_address *target;
113	u16 source;
114	u8 register_num;
115
116} acpi_fadt_pm_info;
117
118static struct acpi_fadt_pm_info fadt_pm_info_table[] = {
119	{&acpi_gbl_xpm1a_status,
120	 ACPI_FADT_OFFSET(xpm1a_event_block),
121	 0},
122
123	{&acpi_gbl_xpm1a_enable,
124	 ACPI_FADT_OFFSET(xpm1a_event_block),
125	 1},
126
127	{&acpi_gbl_xpm1b_status,
128	 ACPI_FADT_OFFSET(xpm1b_event_block),
129	 0},
130
131	{&acpi_gbl_xpm1b_enable,
132	 ACPI_FADT_OFFSET(xpm1b_event_block),
133	 1}
134};
135
136#define ACPI_FADT_PM_INFO_ENTRIES \
137			(sizeof (fadt_pm_info_table) / sizeof (struct acpi_fadt_pm_info))
138
139/*******************************************************************************
140 *
141 * FUNCTION:    acpi_tb_init_generic_address
142 *
143 * PARAMETERS:  generic_address     - GAS struct to be initialized
144 *              space_id            - ACPI Space ID for this register
145 *              byte_width          - Width of this register
146 *              address             - Address of the register
147 *              register_name       - ASCII name of the ACPI register
148 *
149 * RETURN:      None
150 *
151 * DESCRIPTION: Initialize a Generic Address Structure (GAS)
152 *              See the ACPI specification for a full description and
153 *              definition of this structure.
154 *
155 ******************************************************************************/
156
157static void
158acpi_tb_init_generic_address(struct acpi_generic_address *generic_address,
159			     u8 space_id,
160			     u8 byte_width,
161			     u64 address, const char *register_name, u8 flags)
162{
163	u8 bit_width;
164
165	/*
166	 * Bit width field in the GAS is only one byte long, 255 max.
167	 * Check for bit_width overflow in GAS.
168	 */
169	bit_width = (u8)(byte_width * 8);
170	if (byte_width > 31) {	/* (31*8)=248, (32*8)=256 */
171		/*
172		 * No error for GPE blocks, because we do not use the bit_width
173		 * for GPEs, the legacy length (byte_width) is used instead to
174		 * allow for a large number of GPEs.
175		 */
176		if (!(flags & ACPI_FADT_GPE_REGISTER)) {
177			ACPI_ERROR((AE_INFO,
178				    "%s - 32-bit FADT register is too long (%u bytes, %u bits) "
179				    "to convert to GAS struct - 255 bits max, truncating",
180				    register_name, byte_width,
181				    (byte_width * 8)));
182		}
183
184		bit_width = 255;
185	}
186
187	/*
188	 * The 64-bit Address field is non-aligned in the byte packed
189	 * GAS struct.
190	 */
191	ACPI_MOVE_64_TO_64(&generic_address->address, &address);
192
193	/* All other fields are byte-wide */
194
195	generic_address->space_id = space_id;
196	generic_address->bit_width = bit_width;
197	generic_address->bit_offset = 0;
198	generic_address->access_width = 0;	/* Access width ANY */
199}
200
201/*******************************************************************************
202 *
203 * FUNCTION:    acpi_tb_select_address
204 *
205 * PARAMETERS:  register_name       - ASCII name of the ACPI register
206 *              address32           - 32-bit address of the register
207 *              address64           - 64-bit address of the register
208 *
209 * RETURN:      The resolved 64-bit address
210 *
211 * DESCRIPTION: Select between 32-bit and 64-bit versions of addresses within
212 *              the FADT. Used for the FACS and DSDT addresses.
213 *
214 * NOTES:
215 *
216 * Check for FACS and DSDT address mismatches. An address mismatch between
217 * the 32-bit and 64-bit address fields (FIRMWARE_CTRL/X_FIRMWARE_CTRL and
218 * DSDT/X_DSDT) could be a corrupted address field or it might indicate
219 * the presence of two FACS or two DSDT tables.
220 *
221 * November 2013:
222 * By default, as per the ACPICA specification, a valid 64-bit address is
223 * used regardless of the value of the 32-bit address. However, this
224 * behavior can be overridden via the acpi_gbl_use32_bit_fadt_addresses flag.
225 *
226 ******************************************************************************/
227
228static u64
229acpi_tb_select_address(char *register_name, u32 address32, u64 address64)
230{
231
232	if (!address64) {
233
234		/* 64-bit address is zero, use 32-bit address */
235
236		return ((u64)address32);
237	}
238
239	if (address32 && (address64 != (u64)address32)) {
240
241		/* Address mismatch between 32-bit and 64-bit versions */
242
243		ACPI_BIOS_WARNING((AE_INFO,
244				   "32/64X %s address mismatch in FADT: "
245				   "0x%8.8X/0x%8.8X%8.8X, using %u-bit address",
246				   register_name, address32,
247				   ACPI_FORMAT_UINT64(address64),
248				   acpi_gbl_use32_bit_fadt_addresses ? 32 :
249				   64));
250
251		/* 32-bit address override */
252
253		if (acpi_gbl_use32_bit_fadt_addresses) {
254			return ((u64)address32);
255		}
256	}
257
258	/* Default is to use the 64-bit address */
259
260	return (address64);
261}
262
263/*******************************************************************************
264 *
265 * FUNCTION:    acpi_tb_parse_fadt
266 *
267 * PARAMETERS:  None
268 *
269 * RETURN:      None
270 *
271 * DESCRIPTION: Initialize the FADT, DSDT and FACS tables
272 *              (FADT contains the addresses of the DSDT and FACS)
273 *
274 ******************************************************************************/
275
276void acpi_tb_parse_fadt(void)
277{
278	u32 length;
279	struct acpi_table_header *table;
280	struct acpi_table_desc *fadt_desc;
281	acpi_status status;
282
283	/*
284	 * The FADT has multiple versions with different lengths,
285	 * and it contains pointers to both the DSDT and FACS tables.
286	 *
287	 * Get a local copy of the FADT and convert it to a common format
288	 * Map entire FADT, assumed to be smaller than one page.
289	 */
290	fadt_desc = &acpi_gbl_root_table_list.tables[acpi_gbl_fadt_index];
291	status = acpi_tb_get_table(fadt_desc, &table);
292	if (ACPI_FAILURE(status)) {
293		return;
294	}
295	length = fadt_desc->length;
296
297	/*
298	 * Validate the FADT checksum before we copy the table. Ignore
299	 * checksum error as we want to try to get the DSDT and FACS.
300	 */
301	(void)acpi_ut_verify_checksum(table, length);
302
303	/* Create a local copy of the FADT in common ACPI 2.0+ format */
304
305	acpi_tb_create_local_fadt(table, length);
306
307	/* All done with the real FADT, unmap it */
308
309	acpi_tb_put_table(fadt_desc);
310
311	/* Obtain the DSDT and FACS tables via their addresses within the FADT */
312
313	acpi_tb_install_standard_table((acpi_physical_address)acpi_gbl_FADT.
314				       Xdsdt,
315				       ACPI_TABLE_ORIGIN_INTERNAL_PHYSICAL,
316				       NULL, FALSE, TRUE, &acpi_gbl_dsdt_index);
317
318	/* If Hardware Reduced flag is set, there is no FACS */
319
320	if (!acpi_gbl_reduced_hardware) {
321		if (acpi_gbl_FADT.facs) {
322			acpi_tb_install_standard_table((acpi_physical_address)
323						       acpi_gbl_FADT.facs,
324						       ACPI_TABLE_ORIGIN_INTERNAL_PHYSICAL,
325						       NULL, FALSE, TRUE,
326						       &acpi_gbl_facs_index);
327		}
328		if (acpi_gbl_FADT.Xfacs) {
329			acpi_tb_install_standard_table((acpi_physical_address)
330						       acpi_gbl_FADT.Xfacs,
331						       ACPI_TABLE_ORIGIN_INTERNAL_PHYSICAL,
332						       NULL, FALSE, TRUE,
333						       &acpi_gbl_xfacs_index);
334		}
335	}
336}
337
338/*******************************************************************************
339 *
340 * FUNCTION:    acpi_tb_create_local_fadt
341 *
342 * PARAMETERS:  table               - Pointer to BIOS FADT
343 *              length              - Length of the table
344 *
345 * RETURN:      None
346 *
347 * DESCRIPTION: Get a local copy of the FADT and convert it to a common format.
348 *              Performs validation on some important FADT fields.
349 *
350 * NOTE:        We create a local copy of the FADT regardless of the version.
351 *
352 ******************************************************************************/
353
354void acpi_tb_create_local_fadt(struct acpi_table_header *table, u32 length)
355{
356	/*
357	 * Check if the FADT is larger than the largest table that we expect
358	 * (typically the current ACPI specification version). If so, truncate
359	 * the table, and issue a warning.
360	 */
361	if (length > sizeof(struct acpi_table_fadt)) {
362		ACPI_BIOS_WARNING((AE_INFO,
363				   "FADT (revision %u) is longer than %s length, "
364				   "truncating length %u to %u",
365				   table->revision, ACPI_FADT_CONFORMANCE,
366				   length,
367				   (u32)sizeof(struct acpi_table_fadt)));
368	}
369
370	/* Clear the entire local FADT */
371
372	memset(&acpi_gbl_FADT, 0, sizeof(struct acpi_table_fadt));
373
374	/* Copy the original FADT, up to sizeof (struct acpi_table_fadt) */
375
376	memcpy(&acpi_gbl_FADT, table,
377	       ACPI_MIN(length, sizeof(struct acpi_table_fadt)));
378
379	/* Take a copy of the Hardware Reduced flag */
380
381	acpi_gbl_reduced_hardware = FALSE;
382	if (acpi_gbl_FADT.flags & ACPI_FADT_HW_REDUCED) {
383		acpi_gbl_reduced_hardware = TRUE;
384	}
385
386	/* Convert the local copy of the FADT to the common internal format */
387
388	acpi_tb_convert_fadt();
389
390	/* Initialize the global ACPI register structures */
391
392	acpi_tb_setup_fadt_registers();
393}
394
395/*******************************************************************************
396 *
397 * FUNCTION:    acpi_tb_convert_fadt
398 *
399 * PARAMETERS:  none - acpi_gbl_FADT is used.
400 *
401 * RETURN:      None
402 *
403 * DESCRIPTION: Converts all versions of the FADT to a common internal format.
404 *              Expand 32-bit addresses to 64-bit as necessary. Also validate
405 *              important fields within the FADT.
406 *
407 * NOTE:        acpi_gbl_FADT must be of size (struct acpi_table_fadt), and must
408 *              contain a copy of the actual BIOS-provided FADT.
409 *
410 * Notes on 64-bit register addresses:
411 *
412 * After this FADT conversion, later ACPICA code will only use the 64-bit "X"
413 * fields of the FADT for all ACPI register addresses.
414 *
415 * The 64-bit X fields are optional extensions to the original 32-bit FADT
416 * V1.0 fields. Even if they are present in the FADT, they are optional and
417 * are unused if the BIOS sets them to zero. Therefore, we must copy/expand
418 * 32-bit V1.0 fields to the 64-bit X fields if the 64-bit X field is originally
419 * zero.
420 *
421 * For ACPI 1.0 FADTs (that contain no 64-bit addresses), all 32-bit address
422 * fields are expanded to the corresponding 64-bit X fields in the internal
423 * common FADT.
424 *
425 * For ACPI 2.0+ FADTs, all valid (non-zero) 32-bit address fields are expanded
426 * to the corresponding 64-bit X fields, if the 64-bit field is originally
427 * zero. Adhering to the ACPI specification, we completely ignore the 32-bit
428 * field if the 64-bit field is valid, regardless of whether the host OS is
429 * 32-bit or 64-bit.
430 *
431 * Possible additional checks:
432 *  (acpi_gbl_FADT.pm1_event_length >= 4)
433 *  (acpi_gbl_FADT.pm1_control_length >= 2)
434 *  (acpi_gbl_FADT.pm_timer_length >= 4)
435 *  Gpe block lengths must be multiple of 2
436 *
437 ******************************************************************************/
438
439static void acpi_tb_convert_fadt(void)
440{
441	const char *name;
442	struct acpi_generic_address *address64;
443	u32 address32;
444	u8 length;
445	u8 flags;
446	u32 i;
447
448	/*
449	 * For ACPI 1.0 FADTs (revision 1 or 2), ensure that reserved fields which
450	 * should be zero are indeed zero. This will workaround BIOSs that
451	 * inadvertently place values in these fields.
452	 *
453	 * The ACPI 1.0 reserved fields that will be zeroed are the bytes located
454	 * at offset 45, 55, 95, and the word located at offset 109, 110.
455	 *
456	 * Note: The FADT revision value is unreliable. Only the length can be
457	 * trusted.
458	 */
459	if (acpi_gbl_FADT.header.length <= ACPI_FADT_V2_SIZE) {
460		acpi_gbl_FADT.preferred_profile = 0;
461		acpi_gbl_FADT.pstate_control = 0;
462		acpi_gbl_FADT.cst_control = 0;
463		acpi_gbl_FADT.boot_flags = 0;
464	}
465
466	/*
467	 * Now we can update the local FADT length to the length of the
468	 * current FADT version as defined by the ACPI specification.
469	 * Thus, we will have a common FADT internally.
470	 */
471	acpi_gbl_FADT.header.length = sizeof(struct acpi_table_fadt);
472
473	/*
474	 * Expand the 32-bit DSDT addresses to 64-bit as necessary.
475	 * Later ACPICA code will always use the X 64-bit field.
476	 */
477	acpi_gbl_FADT.Xdsdt = acpi_tb_select_address("DSDT",
478						     acpi_gbl_FADT.dsdt,
479						     acpi_gbl_FADT.Xdsdt);
480
481	/* If Hardware Reduced flag is set, we are all done */
482
483	if (acpi_gbl_reduced_hardware) {
484		return;
485	}
486
487	/* Examine all of the 64-bit extended address fields (X fields) */
488
489	for (i = 0; i < ACPI_FADT_INFO_ENTRIES; i++) {
490		/*
491		 * Get the 32-bit and 64-bit addresses, as well as the register
492		 * length and register name.
493		 */
494		address32 = *ACPI_ADD_PTR(u32,
495					  &acpi_gbl_FADT,
496					  fadt_info_table[i].address32);
497
498		address64 = ACPI_ADD_PTR(struct acpi_generic_address,
499					 &acpi_gbl_FADT,
500					 fadt_info_table[i].address64);
501
502		length = *ACPI_ADD_PTR(u8,
503				       &acpi_gbl_FADT,
504				       fadt_info_table[i].length);
505
506		name = fadt_info_table[i].name;
507		flags = fadt_info_table[i].flags;
508
509		/*
510		 * Expand the ACPI 1.0 32-bit addresses to the ACPI 2.0 64-bit "X"
511		 * generic address structures as necessary. Later code will always use
512		 * the 64-bit address structures.
513		 *
514		 * November 2013:
515		 * Now always use the 64-bit address if it is valid (non-zero), in
516		 * accordance with the ACPI specification which states that a 64-bit
517		 * address supersedes the 32-bit version. This behavior can be
518		 * overridden by the acpi_gbl_use32_bit_fadt_addresses flag.
519		 *
520		 * During 64-bit address construction and verification,
521		 * these cases are handled:
522		 *
523		 * Address32 zero, Address64 [don't care]   - Use Address64
524		 *
525		 * No override: if acpi_gbl_use32_bit_fadt_addresses is FALSE, and:
526		 * Address32 non-zero, Address64 zero       - Copy/use Address32
527		 * Address32 non-zero == Address64 non-zero - Use Address64
528		 * Address32 non-zero != Address64 non-zero - Warning, use Address64
529		 *
530		 * Override: if acpi_gbl_use32_bit_fadt_addresses is TRUE, and:
531		 * Address32 non-zero, Address64 zero       - Copy/use Address32
532		 * Address32 non-zero == Address64 non-zero - Copy/use Address32
533		 * Address32 non-zero != Address64 non-zero - Warning, copy/use Address32
534		 *
535		 * Note: space_id is always I/O for 32-bit legacy address fields
536		 */
537		if (address32) {
538			if (address64->address) {
539				if (address64->address != (u64)address32) {
540
541					/* Address mismatch */
542
543					ACPI_BIOS_WARNING((AE_INFO,
544							   "32/64X address mismatch in FADT/%s: "
545							   "0x%8.8X/0x%8.8X%8.8X, using %u-bit address",
546							   name, address32,
547							   ACPI_FORMAT_UINT64
548							   (address64->address),
549							   acpi_gbl_use32_bit_fadt_addresses
550							   ? 32 : 64));
551				}
552
553				/*
554				 * For each extended field, check for length mismatch
555				 * between the legacy length field and the corresponding
556				 * 64-bit X length field.
557				 * Note: If the legacy length field is > 0xFF bits, ignore
558				 * this check. (GPE registers can be larger than the
559				 * 64-bit GAS structure can accommodate, 0xFF bits).
560				 */
561				if ((ACPI_MUL_8(length) <= ACPI_UINT8_MAX) &&
562				    (address64->bit_width !=
563				     ACPI_MUL_8(length))) {
564					ACPI_BIOS_WARNING((AE_INFO,
565							   "32/64X length mismatch in FADT/%s: %u/%u",
566							   name,
567							   ACPI_MUL_8(length),
568							   address64->
569							   bit_width));
570				}
571			}
572
573			/*
574			 * Hardware register access code always uses the 64-bit fields.
575			 * So if the 64-bit field is zero or is to be overridden,
576			 * initialize it with the 32-bit fields.
577			 * Note that when the 32-bit address favor is specified, the
578			 * 64-bit fields are always re-initialized so that
579			 * access_size/bit_width/bit_offset fields can be correctly
580			 * configured to the values to trigger a 32-bit compatible
581			 * access mode in the hardware register access code.
582			 */
583			if (!address64->address
584			    || acpi_gbl_use32_bit_fadt_addresses) {
585				acpi_tb_init_generic_address(address64,
586							     ACPI_ADR_SPACE_SYSTEM_IO,
587							     length,
588							     (u64)address32,
589							     name, flags);
590			}
591		}
592
593		if (fadt_info_table[i].flags & ACPI_FADT_REQUIRED) {
594			/*
595			 * Field is required (Pm1a_event, Pm1a_control).
596			 * Both the address and length must be non-zero.
597			 */
598			if (!address64->address || !length) {
599				ACPI_BIOS_ERROR((AE_INFO,
600						 "Required FADT field %s has zero address and/or length: "
601						 "0x%8.8X%8.8X/0x%X",
602						 name,
603						 ACPI_FORMAT_UINT64(address64->
604								    address),
605						 length));
606			}
607		} else if (fadt_info_table[i].flags & ACPI_FADT_SEPARATE_LENGTH) {
608			/*
609			 * Field is optional (Pm2_control, GPE0, GPE1) AND has its own
610			 * length field. If present, both the address and length must
611			 * be valid.
612			 */
613			if ((address64->address && !length) ||
614			    (!address64->address && length)) {
615				ACPI_BIOS_WARNING((AE_INFO,
616						   "Optional FADT field %s has valid %s but zero %s: "
617						   "0x%8.8X%8.8X/0x%X", name,
618						   (length ? "Length" :
619						    "Address"),
620						   (length ? "Address" :
621						    "Length"),
622						   ACPI_FORMAT_UINT64
623						   (address64->address),
624						   length));
625			}
626		}
627	}
628}
629
630/*******************************************************************************
631 *
632 * FUNCTION:    acpi_tb_setup_fadt_registers
633 *
634 * PARAMETERS:  None, uses acpi_gbl_FADT.
635 *
636 * RETURN:      None
637 *
638 * DESCRIPTION: Initialize global ACPI PM1 register definitions. Optionally,
639 *              force FADT register definitions to their default lengths.
640 *
641 ******************************************************************************/
642
643static void acpi_tb_setup_fadt_registers(void)
644{
645	struct acpi_generic_address *target64;
646	struct acpi_generic_address *source64;
647	u8 pm1_register_byte_width;
648	u32 i;
649
650	/*
651	 * Optionally check all register lengths against the default values and
652	 * update them if they are incorrect.
653	 */
654	if (acpi_gbl_use_default_register_widths) {
655		for (i = 0; i < ACPI_FADT_INFO_ENTRIES; i++) {
656			target64 =
657			    ACPI_ADD_PTR(struct acpi_generic_address,
658					 &acpi_gbl_FADT,
659					 fadt_info_table[i].address64);
660
661			/*
662			 * If a valid register (Address != 0) and the (default_length > 0)
663			 * (Not a GPE register), then check the width against the default.
664			 */
665			if ((target64->address) &&
666			    (fadt_info_table[i].default_length > 0) &&
667			    (fadt_info_table[i].default_length !=
668			     target64->bit_width)) {
669				ACPI_BIOS_WARNING((AE_INFO,
670						   "Invalid length for FADT/%s: %u, using default %u",
671						   fadt_info_table[i].name,
672						   target64->bit_width,
673						   fadt_info_table[i].
674						   default_length));
675
676				/* Incorrect size, set width to the default */
677
678				target64->bit_width =
679				    fadt_info_table[i].default_length;
680			}
681		}
682	}
683
684	/*
685	 * Get the length of the individual PM1 registers (enable and status).
686	 * Each register is defined to be (event block length / 2). Extra divide
687	 * by 8 converts bits to bytes.
688	 */
689	pm1_register_byte_width = (u8)
690	    ACPI_DIV_16(acpi_gbl_FADT.xpm1a_event_block.bit_width);
691
692	/*
693	 * Calculate separate GAS structs for the PM1x (A/B) Status and Enable
694	 * registers. These addresses do not appear (directly) in the FADT, so it
695	 * is useful to pre-calculate them from the PM1 Event Block definitions.
696	 *
697	 * The PM event blocks are split into two register blocks, first is the
698	 * PM Status Register block, followed immediately by the PM Enable
699	 * Register block. Each is of length (pm1_event_length/2)
700	 *
701	 * Note: The PM1A event block is required by the ACPI specification.
702	 * However, the PM1B event block is optional and is rarely, if ever,
703	 * used.
704	 */
705
706	for (i = 0; i < ACPI_FADT_PM_INFO_ENTRIES; i++) {
707		source64 =
708		    ACPI_ADD_PTR(struct acpi_generic_address, &acpi_gbl_FADT,
709				 fadt_pm_info_table[i].source);
710
711		if (source64->address) {
712			acpi_tb_init_generic_address(fadt_pm_info_table[i].
713						     target, source64->space_id,
714						     pm1_register_byte_width,
715						     source64->address +
716						     (fadt_pm_info_table[i].
717						      register_num *
718						      pm1_register_byte_width),
719						     "PmRegisters", 0);
720		}
721	}
722}
723