xref: /linux/drivers/acpi/acpica/tbfadt.c (revision 7aacf86b75bc5523d20fd9127104384fce51ce9c)
1 /******************************************************************************
2  *
3  * Module Name: tbfadt   - FADT table utilities
4  *
5  *****************************************************************************/
6 
7 /*
8  * Copyright (C) 2000 - 2017, Intel Corp.
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 
44 #include <acpi/acpi.h>
45 #include "accommon.h"
46 #include "actables.h"
47 
48 #define _COMPONENT          ACPI_TABLES
49 ACPI_MODULE_NAME("tbfadt")
50 
51 /* Local prototypes */
52 static void
53 acpi_tb_init_generic_address(struct acpi_generic_address *generic_address,
54 			     u8 space_id,
55 			     u8 byte_width,
56 			     u64 address, const char *register_name, u8 flags);
57 
58 static void acpi_tb_convert_fadt(void);
59 
60 static void acpi_tb_setup_fadt_registers(void);
61 
62 static u64
63 acpi_tb_select_address(char *register_name, u32 address32, u64 address64);
64 
65 /* Table for conversion of FADT to common internal format and FADT validation */
66 
67 typedef struct acpi_fadt_info {
68 	const char *name;
69 	u16 address64;
70 	u16 address32;
71 	u16 length;
72 	u8 default_length;
73 	u8 flags;
74 
75 } acpi_fadt_info;
76 
77 #define ACPI_FADT_OPTIONAL          0
78 #define ACPI_FADT_REQUIRED          1
79 #define ACPI_FADT_SEPARATE_LENGTH   2
80 #define ACPI_FADT_GPE_REGISTER      4
81 
82 static struct acpi_fadt_info fadt_info_table[] = {
83 	{"Pm1aEventBlock",
84 	 ACPI_FADT_OFFSET(xpm1a_event_block),
85 	 ACPI_FADT_OFFSET(pm1a_event_block),
86 	 ACPI_FADT_OFFSET(pm1_event_length),
87 	 ACPI_PM1_REGISTER_WIDTH * 2,	/* Enable + Status register */
88 	 ACPI_FADT_REQUIRED},
89 
90 	{"Pm1bEventBlock",
91 	 ACPI_FADT_OFFSET(xpm1b_event_block),
92 	 ACPI_FADT_OFFSET(pm1b_event_block),
93 	 ACPI_FADT_OFFSET(pm1_event_length),
94 	 ACPI_PM1_REGISTER_WIDTH * 2,	/* Enable + Status register */
95 	 ACPI_FADT_OPTIONAL},
96 
97 	{"Pm1aControlBlock",
98 	 ACPI_FADT_OFFSET(xpm1a_control_block),
99 	 ACPI_FADT_OFFSET(pm1a_control_block),
100 	 ACPI_FADT_OFFSET(pm1_control_length),
101 	 ACPI_PM1_REGISTER_WIDTH,
102 	 ACPI_FADT_REQUIRED},
103 
104 	{"Pm1bControlBlock",
105 	 ACPI_FADT_OFFSET(xpm1b_control_block),
106 	 ACPI_FADT_OFFSET(pm1b_control_block),
107 	 ACPI_FADT_OFFSET(pm1_control_length),
108 	 ACPI_PM1_REGISTER_WIDTH,
109 	 ACPI_FADT_OPTIONAL},
110 
111 	{"Pm2ControlBlock",
112 	 ACPI_FADT_OFFSET(xpm2_control_block),
113 	 ACPI_FADT_OFFSET(pm2_control_block),
114 	 ACPI_FADT_OFFSET(pm2_control_length),
115 	 ACPI_PM2_REGISTER_WIDTH,
116 	 ACPI_FADT_SEPARATE_LENGTH},
117 
118 	{"PmTimerBlock",
119 	 ACPI_FADT_OFFSET(xpm_timer_block),
120 	 ACPI_FADT_OFFSET(pm_timer_block),
121 	 ACPI_FADT_OFFSET(pm_timer_length),
122 	 ACPI_PM_TIMER_WIDTH,
123 	 ACPI_FADT_SEPARATE_LENGTH},	/* ACPI 5.0A: Timer is optional */
124 
125 	{"Gpe0Block",
126 	 ACPI_FADT_OFFSET(xgpe0_block),
127 	 ACPI_FADT_OFFSET(gpe0_block),
128 	 ACPI_FADT_OFFSET(gpe0_block_length),
129 	 0,
130 	 ACPI_FADT_SEPARATE_LENGTH | ACPI_FADT_GPE_REGISTER},
131 
132 	{"Gpe1Block",
133 	 ACPI_FADT_OFFSET(xgpe1_block),
134 	 ACPI_FADT_OFFSET(gpe1_block),
135 	 ACPI_FADT_OFFSET(gpe1_block_length),
136 	 0,
137 	 ACPI_FADT_SEPARATE_LENGTH | ACPI_FADT_GPE_REGISTER}
138 };
139 
140 #define ACPI_FADT_INFO_ENTRIES \
141 			(sizeof (fadt_info_table) / sizeof (struct acpi_fadt_info))
142 
143 /* Table used to split Event Blocks into separate status/enable registers */
144 
145 typedef struct acpi_fadt_pm_info {
146 	struct acpi_generic_address *target;
147 	u16 source;
148 	u8 register_num;
149 
150 } acpi_fadt_pm_info;
151 
152 static struct acpi_fadt_pm_info fadt_pm_info_table[] = {
153 	{&acpi_gbl_xpm1a_status,
154 	 ACPI_FADT_OFFSET(xpm1a_event_block),
155 	 0},
156 
157 	{&acpi_gbl_xpm1a_enable,
158 	 ACPI_FADT_OFFSET(xpm1a_event_block),
159 	 1},
160 
161 	{&acpi_gbl_xpm1b_status,
162 	 ACPI_FADT_OFFSET(xpm1b_event_block),
163 	 0},
164 
165 	{&acpi_gbl_xpm1b_enable,
166 	 ACPI_FADT_OFFSET(xpm1b_event_block),
167 	 1}
168 };
169 
170 #define ACPI_FADT_PM_INFO_ENTRIES \
171 			(sizeof (fadt_pm_info_table) / sizeof (struct acpi_fadt_pm_info))
172 
173 /*******************************************************************************
174  *
175  * FUNCTION:    acpi_tb_init_generic_address
176  *
177  * PARAMETERS:  generic_address     - GAS struct to be initialized
178  *              space_id            - ACPI Space ID for this register
179  *              byte_width          - Width of this register
180  *              address             - Address of the register
181  *              register_name       - ASCII name of the ACPI register
182  *
183  * RETURN:      None
184  *
185  * DESCRIPTION: Initialize a Generic Address Structure (GAS)
186  *              See the ACPI specification for a full description and
187  *              definition of this structure.
188  *
189  ******************************************************************************/
190 
191 static void
192 acpi_tb_init_generic_address(struct acpi_generic_address *generic_address,
193 			     u8 space_id,
194 			     u8 byte_width,
195 			     u64 address, const char *register_name, u8 flags)
196 {
197 	u8 bit_width;
198 
199 	/*
200 	 * Bit width field in the GAS is only one byte long, 255 max.
201 	 * Check for bit_width overflow in GAS.
202 	 */
203 	bit_width = (u8)(byte_width * 8);
204 	if (byte_width > 31) {	/* (31*8)=248, (32*8)=256 */
205 		/*
206 		 * No error for GPE blocks, because we do not use the bit_width
207 		 * for GPEs, the legacy length (byte_width) is used instead to
208 		 * allow for a large number of GPEs.
209 		 */
210 		if (!(flags & ACPI_FADT_GPE_REGISTER)) {
211 			ACPI_ERROR((AE_INFO,
212 				    "%s - 32-bit FADT register is too long (%u bytes, %u bits) "
213 				    "to convert to GAS struct - 255 bits max, truncating",
214 				    register_name, byte_width,
215 				    (byte_width * 8)));
216 		}
217 
218 		bit_width = 255;
219 	}
220 
221 	/*
222 	 * The 64-bit Address field is non-aligned in the byte packed
223 	 * GAS struct.
224 	 */
225 	ACPI_MOVE_64_TO_64(&generic_address->address, &address);
226 
227 	/* All other fields are byte-wide */
228 
229 	generic_address->space_id = space_id;
230 	generic_address->bit_width = bit_width;
231 	generic_address->bit_offset = 0;
232 	generic_address->access_width = 0;	/* Access width ANY */
233 }
234 
235 /*******************************************************************************
236  *
237  * FUNCTION:    acpi_tb_select_address
238  *
239  * PARAMETERS:  register_name       - ASCII name of the ACPI register
240  *              address32           - 32-bit address of the register
241  *              address64           - 64-bit address of the register
242  *
243  * RETURN:      The resolved 64-bit address
244  *
245  * DESCRIPTION: Select between 32-bit and 64-bit versions of addresses within
246  *              the FADT. Used for the FACS and DSDT addresses.
247  *
248  * NOTES:
249  *
250  * Check for FACS and DSDT address mismatches. An address mismatch between
251  * the 32-bit and 64-bit address fields (FIRMWARE_CTRL/X_FIRMWARE_CTRL and
252  * DSDT/X_DSDT) could be a corrupted address field or it might indicate
253  * the presence of two FACS or two DSDT tables.
254  *
255  * November 2013:
256  * By default, as per the ACPICA specification, a valid 64-bit address is
257  * used regardless of the value of the 32-bit address. However, this
258  * behavior can be overridden via the acpi_gbl_use32_bit_fadt_addresses flag.
259  *
260  ******************************************************************************/
261 
262 static u64
263 acpi_tb_select_address(char *register_name, u32 address32, u64 address64)
264 {
265 
266 	if (!address64) {
267 
268 		/* 64-bit address is zero, use 32-bit address */
269 
270 		return ((u64)address32);
271 	}
272 
273 	if (address32 && (address64 != (u64)address32)) {
274 
275 		/* Address mismatch between 32-bit and 64-bit versions */
276 
277 		ACPI_BIOS_WARNING((AE_INFO,
278 				   "32/64X %s address mismatch in FADT: "
279 				   "0x%8.8X/0x%8.8X%8.8X, using %u-bit address",
280 				   register_name, address32,
281 				   ACPI_FORMAT_UINT64(address64),
282 				   acpi_gbl_use32_bit_fadt_addresses ? 32 :
283 				   64));
284 
285 		/* 32-bit address override */
286 
287 		if (acpi_gbl_use32_bit_fadt_addresses) {
288 			return ((u64)address32);
289 		}
290 	}
291 
292 	/* Default is to use the 64-bit address */
293 
294 	return (address64);
295 }
296 
297 /*******************************************************************************
298  *
299  * FUNCTION:    acpi_tb_parse_fadt
300  *
301  * PARAMETERS:  None
302  *
303  * RETURN:      None
304  *
305  * DESCRIPTION: Initialize the FADT, DSDT and FACS tables
306  *              (FADT contains the addresses of the DSDT and FACS)
307  *
308  ******************************************************************************/
309 
310 void acpi_tb_parse_fadt(void)
311 {
312 	u32 length;
313 	struct acpi_table_header *table;
314 	struct acpi_table_desc *fadt_desc;
315 	acpi_status status;
316 
317 	/*
318 	 * The FADT has multiple versions with different lengths,
319 	 * and it contains pointers to both the DSDT and FACS tables.
320 	 *
321 	 * Get a local copy of the FADT and convert it to a common format
322 	 * Map entire FADT, assumed to be smaller than one page.
323 	 */
324 	fadt_desc = &acpi_gbl_root_table_list.tables[acpi_gbl_fadt_index];
325 	status = acpi_tb_get_table(fadt_desc, &table);
326 	if (ACPI_FAILURE(status)) {
327 		return;
328 	}
329 	length = fadt_desc->length;
330 
331 	/*
332 	 * Validate the FADT checksum before we copy the table. Ignore
333 	 * checksum error as we want to try to get the DSDT and FACS.
334 	 */
335 	(void)acpi_tb_verify_checksum(table, length);
336 
337 	/* Create a local copy of the FADT in common ACPI 2.0+ format */
338 
339 	acpi_tb_create_local_fadt(table, length);
340 
341 	/* All done with the real FADT, unmap it */
342 
343 	acpi_tb_put_table(fadt_desc);
344 
345 	/* Obtain the DSDT and FACS tables via their addresses within the FADT */
346 
347 	acpi_tb_install_standard_table((acpi_physical_address)acpi_gbl_FADT.
348 				       Xdsdt,
349 				       ACPI_TABLE_ORIGIN_INTERNAL_PHYSICAL,
350 				       FALSE, TRUE, &acpi_gbl_dsdt_index);
351 
352 	/* If Hardware Reduced flag is set, there is no FACS */
353 
354 	if (!acpi_gbl_reduced_hardware) {
355 		if (acpi_gbl_FADT.facs) {
356 			acpi_tb_install_standard_table((acpi_physical_address)
357 						       acpi_gbl_FADT.facs,
358 						       ACPI_TABLE_ORIGIN_INTERNAL_PHYSICAL,
359 						       FALSE, TRUE,
360 						       &acpi_gbl_facs_index);
361 		}
362 		if (acpi_gbl_FADT.Xfacs) {
363 			acpi_tb_install_standard_table((acpi_physical_address)
364 						       acpi_gbl_FADT.Xfacs,
365 						       ACPI_TABLE_ORIGIN_INTERNAL_PHYSICAL,
366 						       FALSE, TRUE,
367 						       &acpi_gbl_xfacs_index);
368 		}
369 	}
370 }
371 
372 /*******************************************************************************
373  *
374  * FUNCTION:    acpi_tb_create_local_fadt
375  *
376  * PARAMETERS:  table               - Pointer to BIOS FADT
377  *              length              - Length of the table
378  *
379  * RETURN:      None
380  *
381  * DESCRIPTION: Get a local copy of the FADT and convert it to a common format.
382  *              Performs validation on some important FADT fields.
383  *
384  * NOTE:        We create a local copy of the FADT regardless of the version.
385  *
386  ******************************************************************************/
387 
388 void acpi_tb_create_local_fadt(struct acpi_table_header *table, u32 length)
389 {
390 	/*
391 	 * Check if the FADT is larger than the largest table that we expect
392 	 * (typically the current ACPI specification version). If so, truncate
393 	 * the table, and issue a warning.
394 	 */
395 	if (length > sizeof(struct acpi_table_fadt)) {
396 		ACPI_BIOS_WARNING((AE_INFO,
397 				   "FADT (revision %u) is longer than %s length, "
398 				   "truncating length %u to %u",
399 				   table->revision, ACPI_FADT_CONFORMANCE,
400 				   length,
401 				   (u32)sizeof(struct acpi_table_fadt)));
402 	}
403 
404 	/* Clear the entire local FADT */
405 
406 	memset(&acpi_gbl_FADT, 0, sizeof(struct acpi_table_fadt));
407 
408 	/* Copy the original FADT, up to sizeof (struct acpi_table_fadt) */
409 
410 	memcpy(&acpi_gbl_FADT, table,
411 	       ACPI_MIN(length, sizeof(struct acpi_table_fadt)));
412 
413 	/* Take a copy of the Hardware Reduced flag */
414 
415 	acpi_gbl_reduced_hardware = FALSE;
416 	if (acpi_gbl_FADT.flags & ACPI_FADT_HW_REDUCED) {
417 		acpi_gbl_reduced_hardware = TRUE;
418 	}
419 
420 	/* Convert the local copy of the FADT to the common internal format */
421 
422 	acpi_tb_convert_fadt();
423 
424 	/* Initialize the global ACPI register structures */
425 
426 	acpi_tb_setup_fadt_registers();
427 }
428 
429 /*******************************************************************************
430  *
431  * FUNCTION:    acpi_tb_convert_fadt
432  *
433  * PARAMETERS:  none - acpi_gbl_FADT is used.
434  *
435  * RETURN:      None
436  *
437  * DESCRIPTION: Converts all versions of the FADT to a common internal format.
438  *              Expand 32-bit addresses to 64-bit as necessary. Also validate
439  *              important fields within the FADT.
440  *
441  * NOTE:        acpi_gbl_FADT must be of size (struct acpi_table_fadt), and must
442  *              contain a copy of the actual BIOS-provided FADT.
443  *
444  * Notes on 64-bit register addresses:
445  *
446  * After this FADT conversion, later ACPICA code will only use the 64-bit "X"
447  * fields of the FADT for all ACPI register addresses.
448  *
449  * The 64-bit X fields are optional extensions to the original 32-bit FADT
450  * V1.0 fields. Even if they are present in the FADT, they are optional and
451  * are unused if the BIOS sets them to zero. Therefore, we must copy/expand
452  * 32-bit V1.0 fields to the 64-bit X fields if the 64-bit X field is originally
453  * zero.
454  *
455  * For ACPI 1.0 FADTs (that contain no 64-bit addresses), all 32-bit address
456  * fields are expanded to the corresponding 64-bit X fields in the internal
457  * common FADT.
458  *
459  * For ACPI 2.0+ FADTs, all valid (non-zero) 32-bit address fields are expanded
460  * to the corresponding 64-bit X fields, if the 64-bit field is originally
461  * zero. Adhering to the ACPI specification, we completely ignore the 32-bit
462  * field if the 64-bit field is valid, regardless of whether the host OS is
463  * 32-bit or 64-bit.
464  *
465  * Possible additional checks:
466  *  (acpi_gbl_FADT.pm1_event_length >= 4)
467  *  (acpi_gbl_FADT.pm1_control_length >= 2)
468  *  (acpi_gbl_FADT.pm_timer_length >= 4)
469  *  Gpe block lengths must be multiple of 2
470  *
471  ******************************************************************************/
472 
473 static void acpi_tb_convert_fadt(void)
474 {
475 	const char *name;
476 	struct acpi_generic_address *address64;
477 	u32 address32;
478 	u8 length;
479 	u8 flags;
480 	u32 i;
481 
482 	/*
483 	 * For ACPI 1.0 FADTs (revision 1 or 2), ensure that reserved fields which
484 	 * should be zero are indeed zero. This will workaround BIOSs that
485 	 * inadvertently place values in these fields.
486 	 *
487 	 * The ACPI 1.0 reserved fields that will be zeroed are the bytes located
488 	 * at offset 45, 55, 95, and the word located at offset 109, 110.
489 	 *
490 	 * Note: The FADT revision value is unreliable. Only the length can be
491 	 * trusted.
492 	 */
493 	if (acpi_gbl_FADT.header.length <= ACPI_FADT_V2_SIZE) {
494 		acpi_gbl_FADT.preferred_profile = 0;
495 		acpi_gbl_FADT.pstate_control = 0;
496 		acpi_gbl_FADT.cst_control = 0;
497 		acpi_gbl_FADT.boot_flags = 0;
498 	}
499 
500 	/*
501 	 * Now we can update the local FADT length to the length of the
502 	 * current FADT version as defined by the ACPI specification.
503 	 * Thus, we will have a common FADT internally.
504 	 */
505 	acpi_gbl_FADT.header.length = sizeof(struct acpi_table_fadt);
506 
507 	/*
508 	 * Expand the 32-bit DSDT addresses to 64-bit as necessary.
509 	 * Later ACPICA code will always use the X 64-bit field.
510 	 */
511 	acpi_gbl_FADT.Xdsdt = acpi_tb_select_address("DSDT",
512 						     acpi_gbl_FADT.dsdt,
513 						     acpi_gbl_FADT.Xdsdt);
514 
515 	/* If Hardware Reduced flag is set, we are all done */
516 
517 	if (acpi_gbl_reduced_hardware) {
518 		return;
519 	}
520 
521 	/* Examine all of the 64-bit extended address fields (X fields) */
522 
523 	for (i = 0; i < ACPI_FADT_INFO_ENTRIES; i++) {
524 		/*
525 		 * Get the 32-bit and 64-bit addresses, as well as the register
526 		 * length and register name.
527 		 */
528 		address32 = *ACPI_ADD_PTR(u32,
529 					  &acpi_gbl_FADT,
530 					  fadt_info_table[i].address32);
531 
532 		address64 = ACPI_ADD_PTR(struct acpi_generic_address,
533 					 &acpi_gbl_FADT,
534 					 fadt_info_table[i].address64);
535 
536 		length = *ACPI_ADD_PTR(u8,
537 				       &acpi_gbl_FADT,
538 				       fadt_info_table[i].length);
539 
540 		name = fadt_info_table[i].name;
541 		flags = fadt_info_table[i].flags;
542 
543 		/*
544 		 * Expand the ACPI 1.0 32-bit addresses to the ACPI 2.0 64-bit "X"
545 		 * generic address structures as necessary. Later code will always use
546 		 * the 64-bit address structures.
547 		 *
548 		 * November 2013:
549 		 * Now always use the 64-bit address if it is valid (non-zero), in
550 		 * accordance with the ACPI specification which states that a 64-bit
551 		 * address supersedes the 32-bit version. This behavior can be
552 		 * overridden by the acpi_gbl_use32_bit_fadt_addresses flag.
553 		 *
554 		 * During 64-bit address construction and verification,
555 		 * these cases are handled:
556 		 *
557 		 * Address32 zero, Address64 [don't care]   - Use Address64
558 		 *
559 		 * No override: if acpi_gbl_use32_bit_fadt_addresses is FALSE, and:
560 		 * Address32 non-zero, Address64 zero       - Copy/use Address32
561 		 * Address32 non-zero == Address64 non-zero - Use Address64
562 		 * Address32 non-zero != Address64 non-zero - Warning, use Address64
563 		 *
564 		 * Override: if acpi_gbl_use32_bit_fadt_addresses is TRUE, and:
565 		 * Address32 non-zero, Address64 zero       - Copy/use Address32
566 		 * Address32 non-zero == Address64 non-zero - Copy/use Address32
567 		 * Address32 non-zero != Address64 non-zero - Warning, copy/use Address32
568 		 *
569 		 * Note: space_id is always I/O for 32-bit legacy address fields
570 		 */
571 		if (address32) {
572 			if (address64->address) {
573 				if (address64->address != (u64)address32) {
574 
575 					/* Address mismatch */
576 
577 					ACPI_BIOS_WARNING((AE_INFO,
578 							   "32/64X address mismatch in FADT/%s: "
579 							   "0x%8.8X/0x%8.8X%8.8X, using %u-bit address",
580 							   name, address32,
581 							   ACPI_FORMAT_UINT64
582 							   (address64->address),
583 							   acpi_gbl_use32_bit_fadt_addresses
584 							   ? 32 : 64));
585 				}
586 
587 				/*
588 				 * For each extended field, check for length mismatch
589 				 * between the legacy length field and the corresponding
590 				 * 64-bit X length field.
591 				 * Note: If the legacy length field is > 0xFF bits, ignore
592 				 * this check. (GPE registers can be larger than the
593 				 * 64-bit GAS structure can accomodate, 0xFF bits).
594 				 */
595 				if ((ACPI_MUL_8(length) <= ACPI_UINT8_MAX) &&
596 				    (address64->bit_width !=
597 				     ACPI_MUL_8(length))) {
598 					ACPI_BIOS_WARNING((AE_INFO,
599 							   "32/64X length mismatch in FADT/%s: %u/%u",
600 							   name,
601 							   ACPI_MUL_8(length),
602 							   address64->
603 							   bit_width));
604 				}
605 			}
606 
607 			/*
608 			 * Hardware register access code always uses the 64-bit fields.
609 			 * So if the 64-bit field is zero or is to be overridden,
610 			 * initialize it with the 32-bit fields.
611 			 * Note that when the 32-bit address favor is specified, the
612 			 * 64-bit fields are always re-initialized so that
613 			 * access_size/bit_width/bit_offset fields can be correctly
614 			 * configured to the values to trigger a 32-bit compatible
615 			 * access mode in the hardware register access code.
616 			 */
617 			if (!address64->address
618 			    || acpi_gbl_use32_bit_fadt_addresses) {
619 				acpi_tb_init_generic_address(address64,
620 							     ACPI_ADR_SPACE_SYSTEM_IO,
621 							     length,
622 							     (u64)address32,
623 							     name, flags);
624 			}
625 		}
626 
627 		if (fadt_info_table[i].flags & ACPI_FADT_REQUIRED) {
628 			/*
629 			 * Field is required (Pm1a_event, Pm1a_control).
630 			 * Both the address and length must be non-zero.
631 			 */
632 			if (!address64->address || !length) {
633 				ACPI_BIOS_ERROR((AE_INFO,
634 						 "Required FADT field %s has zero address and/or length: "
635 						 "0x%8.8X%8.8X/0x%X",
636 						 name,
637 						 ACPI_FORMAT_UINT64(address64->
638 								    address),
639 						 length));
640 			}
641 		} else if (fadt_info_table[i].flags & ACPI_FADT_SEPARATE_LENGTH) {
642 			/*
643 			 * Field is optional (Pm2_control, GPE0, GPE1) AND has its own
644 			 * length field. If present, both the address and length must
645 			 * be valid.
646 			 */
647 			if ((address64->address && !length) ||
648 			    (!address64->address && length)) {
649 				ACPI_BIOS_WARNING((AE_INFO,
650 						   "Optional FADT field %s has valid %s but zero %s: "
651 						   "0x%8.8X%8.8X/0x%X", name,
652 						   (length ? "Length" :
653 						    "Address"),
654 						   (length ? "Address" :
655 						    "Length"),
656 						   ACPI_FORMAT_UINT64
657 						   (address64->address),
658 						   length));
659 			}
660 		}
661 	}
662 }
663 
664 /*******************************************************************************
665  *
666  * FUNCTION:    acpi_tb_setup_fadt_registers
667  *
668  * PARAMETERS:  None, uses acpi_gbl_FADT.
669  *
670  * RETURN:      None
671  *
672  * DESCRIPTION: Initialize global ACPI PM1 register definitions. Optionally,
673  *              force FADT register definitions to their default lengths.
674  *
675  ******************************************************************************/
676 
677 static void acpi_tb_setup_fadt_registers(void)
678 {
679 	struct acpi_generic_address *target64;
680 	struct acpi_generic_address *source64;
681 	u8 pm1_register_byte_width;
682 	u32 i;
683 
684 	/*
685 	 * Optionally check all register lengths against the default values and
686 	 * update them if they are incorrect.
687 	 */
688 	if (acpi_gbl_use_default_register_widths) {
689 		for (i = 0; i < ACPI_FADT_INFO_ENTRIES; i++) {
690 			target64 =
691 			    ACPI_ADD_PTR(struct acpi_generic_address,
692 					 &acpi_gbl_FADT,
693 					 fadt_info_table[i].address64);
694 
695 			/*
696 			 * If a valid register (Address != 0) and the (default_length > 0)
697 			 * (Not a GPE register), then check the width against the default.
698 			 */
699 			if ((target64->address) &&
700 			    (fadt_info_table[i].default_length > 0) &&
701 			    (fadt_info_table[i].default_length !=
702 			     target64->bit_width)) {
703 				ACPI_BIOS_WARNING((AE_INFO,
704 						   "Invalid length for FADT/%s: %u, using default %u",
705 						   fadt_info_table[i].name,
706 						   target64->bit_width,
707 						   fadt_info_table[i].
708 						   default_length));
709 
710 				/* Incorrect size, set width to the default */
711 
712 				target64->bit_width =
713 				    fadt_info_table[i].default_length;
714 			}
715 		}
716 	}
717 
718 	/*
719 	 * Get the length of the individual PM1 registers (enable and status).
720 	 * Each register is defined to be (event block length / 2). Extra divide
721 	 * by 8 converts bits to bytes.
722 	 */
723 	pm1_register_byte_width = (u8)
724 	    ACPI_DIV_16(acpi_gbl_FADT.xpm1a_event_block.bit_width);
725 
726 	/*
727 	 * Calculate separate GAS structs for the PM1x (A/B) Status and Enable
728 	 * registers. These addresses do not appear (directly) in the FADT, so it
729 	 * is useful to pre-calculate them from the PM1 Event Block definitions.
730 	 *
731 	 * The PM event blocks are split into two register blocks, first is the
732 	 * PM Status Register block, followed immediately by the PM Enable
733 	 * Register block. Each is of length (pm1_event_length/2)
734 	 *
735 	 * Note: The PM1A event block is required by the ACPI specification.
736 	 * However, the PM1B event block is optional and is rarely, if ever,
737 	 * used.
738 	 */
739 
740 	for (i = 0; i < ACPI_FADT_PM_INFO_ENTRIES; i++) {
741 		source64 =
742 		    ACPI_ADD_PTR(struct acpi_generic_address, &acpi_gbl_FADT,
743 				 fadt_pm_info_table[i].source);
744 
745 		if (source64->address) {
746 			acpi_tb_init_generic_address(fadt_pm_info_table[i].
747 						     target, source64->space_id,
748 						     pm1_register_byte_width,
749 						     source64->address +
750 						     (fadt_pm_info_table[i].
751 						      register_num *
752 						      pm1_register_byte_width),
753 						     "PmRegisters", 0);
754 		}
755 	}
756 }
757