xref: /openbmc/linux/drivers/acpi/acpica/tbfadt.c (revision 5b394b2d)
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 - 2018, Intel Corp.
7  *
8  *****************************************************************************/
9 
10 #include <acpi/acpi.h>
11 #include "accommon.h"
12 #include "actables.h"
13 
14 #define _COMPONENT          ACPI_TABLES
15 ACPI_MODULE_NAME("tbfadt")
16 
17 /* Local prototypes */
18 static void
19 acpi_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 
24 static void acpi_tb_convert_fadt(void);
25 
26 static void acpi_tb_setup_fadt_registers(void);
27 
28 static u64
29 acpi_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 
33 typedef 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 
48 static 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 
111 typedef 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 
118 static 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 
157 static void
158 acpi_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 
228 static u64
229 acpi_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 
276 void 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_tb_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 				       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 						       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 						       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 
354 void 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 
439 static 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 accomodate, 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 
643 static 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