xref: /openbmc/linux/drivers/firmware/dmi_scan.c (revision baa7eb025ab14f3cba2e35c0a8648f9c9f01d24f)
1 #include <linux/types.h>
2 #include <linux/string.h>
3 #include <linux/init.h>
4 #include <linux/module.h>
5 #include <linux/ctype.h>
6 #include <linux/dmi.h>
7 #include <linux/efi.h>
8 #include <linux/bootmem.h>
9 #include <asm/dmi.h>
10 
11 /*
12  * DMI stands for "Desktop Management Interface".  It is part
13  * of and an antecedent to, SMBIOS, which stands for System
14  * Management BIOS.  See further: http://www.dmtf.org/standards
15  */
16 static char dmi_empty_string[] = "        ";
17 
18 /*
19  * Catch too early calls to dmi_check_system():
20  */
21 static int dmi_initialized;
22 
23 static const char * __init dmi_string_nosave(const struct dmi_header *dm, u8 s)
24 {
25 	const u8 *bp = ((u8 *) dm) + dm->length;
26 
27 	if (s) {
28 		s--;
29 		while (s > 0 && *bp) {
30 			bp += strlen(bp) + 1;
31 			s--;
32 		}
33 
34 		if (*bp != 0) {
35 			size_t len = strlen(bp)+1;
36 			size_t cmp_len = len > 8 ? 8 : len;
37 
38 			if (!memcmp(bp, dmi_empty_string, cmp_len))
39 				return dmi_empty_string;
40 			return bp;
41 		}
42 	}
43 
44 	return "";
45 }
46 
47 static char * __init dmi_string(const struct dmi_header *dm, u8 s)
48 {
49 	const char *bp = dmi_string_nosave(dm, s);
50 	char *str;
51 	size_t len;
52 
53 	if (bp == dmi_empty_string)
54 		return dmi_empty_string;
55 
56 	len = strlen(bp) + 1;
57 	str = dmi_alloc(len);
58 	if (str != NULL)
59 		strcpy(str, bp);
60 	else
61 		printk(KERN_ERR "dmi_string: cannot allocate %Zu bytes.\n", len);
62 
63 	return str;
64 }
65 
66 /*
67  *	We have to be cautious here. We have seen BIOSes with DMI pointers
68  *	pointing to completely the wrong place for example
69  */
70 static void dmi_table(u8 *buf, int len, int num,
71 		      void (*decode)(const struct dmi_header *, void *),
72 		      void *private_data)
73 {
74 	u8 *data = buf;
75 	int i = 0;
76 
77 	/*
78 	 *	Stop when we see all the items the table claimed to have
79 	 *	OR we run off the end of the table (also happens)
80 	 */
81 	while ((i < num) && (data - buf + sizeof(struct dmi_header)) <= len) {
82 		const struct dmi_header *dm = (const struct dmi_header *)data;
83 
84 		/*
85 		 *  We want to know the total length (formatted area and
86 		 *  strings) before decoding to make sure we won't run off the
87 		 *  table in dmi_decode or dmi_string
88 		 */
89 		data += dm->length;
90 		while ((data - buf < len - 1) && (data[0] || data[1]))
91 			data++;
92 		if (data - buf < len - 1)
93 			decode(dm, private_data);
94 		data += 2;
95 		i++;
96 	}
97 }
98 
99 static u32 dmi_base;
100 static u16 dmi_len;
101 static u16 dmi_num;
102 
103 static int __init dmi_walk_early(void (*decode)(const struct dmi_header *,
104 		void *))
105 {
106 	u8 *buf;
107 
108 	buf = dmi_ioremap(dmi_base, dmi_len);
109 	if (buf == NULL)
110 		return -1;
111 
112 	dmi_table(buf, dmi_len, dmi_num, decode, NULL);
113 
114 	dmi_iounmap(buf, dmi_len);
115 	return 0;
116 }
117 
118 static int __init dmi_checksum(const u8 *buf)
119 {
120 	u8 sum = 0;
121 	int a;
122 
123 	for (a = 0; a < 15; a++)
124 		sum += buf[a];
125 
126 	return sum == 0;
127 }
128 
129 static char *dmi_ident[DMI_STRING_MAX];
130 static LIST_HEAD(dmi_devices);
131 int dmi_available;
132 
133 /*
134  *	Save a DMI string
135  */
136 static void __init dmi_save_ident(const struct dmi_header *dm, int slot, int string)
137 {
138 	const char *d = (const char*) dm;
139 	char *p;
140 
141 	if (dmi_ident[slot])
142 		return;
143 
144 	p = dmi_string(dm, d[string]);
145 	if (p == NULL)
146 		return;
147 
148 	dmi_ident[slot] = p;
149 }
150 
151 static void __init dmi_save_uuid(const struct dmi_header *dm, int slot, int index)
152 {
153 	const u8 *d = (u8*) dm + index;
154 	char *s;
155 	int is_ff = 1, is_00 = 1, i;
156 
157 	if (dmi_ident[slot])
158 		return;
159 
160 	for (i = 0; i < 16 && (is_ff || is_00); i++) {
161 		if(d[i] != 0x00) is_ff = 0;
162 		if(d[i] != 0xFF) is_00 = 0;
163 	}
164 
165 	if (is_ff || is_00)
166 		return;
167 
168 	s = dmi_alloc(16*2+4+1);
169 	if (!s)
170 		return;
171 
172 	sprintf(s, "%pUB", d);
173 
174         dmi_ident[slot] = s;
175 }
176 
177 static void __init dmi_save_type(const struct dmi_header *dm, int slot, int index)
178 {
179 	const u8 *d = (u8*) dm + index;
180 	char *s;
181 
182 	if (dmi_ident[slot])
183 		return;
184 
185 	s = dmi_alloc(4);
186 	if (!s)
187 		return;
188 
189 	sprintf(s, "%u", *d & 0x7F);
190 	dmi_ident[slot] = s;
191 }
192 
193 static void __init dmi_save_one_device(int type, const char *name)
194 {
195 	struct dmi_device *dev;
196 
197 	/* No duplicate device */
198 	if (dmi_find_device(type, name, NULL))
199 		return;
200 
201 	dev = dmi_alloc(sizeof(*dev) + strlen(name) + 1);
202 	if (!dev) {
203 		printk(KERN_ERR "dmi_save_one_device: out of memory.\n");
204 		return;
205 	}
206 
207 	dev->type = type;
208 	strcpy((char *)(dev + 1), name);
209 	dev->name = (char *)(dev + 1);
210 	dev->device_data = NULL;
211 	list_add(&dev->list, &dmi_devices);
212 }
213 
214 static void __init dmi_save_devices(const struct dmi_header *dm)
215 {
216 	int i, count = (dm->length - sizeof(struct dmi_header)) / 2;
217 
218 	for (i = 0; i < count; i++) {
219 		const char *d = (char *)(dm + 1) + (i * 2);
220 
221 		/* Skip disabled device */
222 		if ((*d & 0x80) == 0)
223 			continue;
224 
225 		dmi_save_one_device(*d & 0x7f, dmi_string_nosave(dm, *(d + 1)));
226 	}
227 }
228 
229 static void __init dmi_save_oem_strings_devices(const struct dmi_header *dm)
230 {
231 	int i, count = *(u8 *)(dm + 1);
232 	struct dmi_device *dev;
233 
234 	for (i = 1; i <= count; i++) {
235 		char *devname = dmi_string(dm, i);
236 
237 		if (devname == dmi_empty_string)
238 			continue;
239 
240 		dev = dmi_alloc(sizeof(*dev));
241 		if (!dev) {
242 			printk(KERN_ERR
243 			   "dmi_save_oem_strings_devices: out of memory.\n");
244 			break;
245 		}
246 
247 		dev->type = DMI_DEV_TYPE_OEM_STRING;
248 		dev->name = devname;
249 		dev->device_data = NULL;
250 
251 		list_add(&dev->list, &dmi_devices);
252 	}
253 }
254 
255 static void __init dmi_save_ipmi_device(const struct dmi_header *dm)
256 {
257 	struct dmi_device *dev;
258 	void * data;
259 
260 	data = dmi_alloc(dm->length);
261 	if (data == NULL) {
262 		printk(KERN_ERR "dmi_save_ipmi_device: out of memory.\n");
263 		return;
264 	}
265 
266 	memcpy(data, dm, dm->length);
267 
268 	dev = dmi_alloc(sizeof(*dev));
269 	if (!dev) {
270 		printk(KERN_ERR "dmi_save_ipmi_device: out of memory.\n");
271 		return;
272 	}
273 
274 	dev->type = DMI_DEV_TYPE_IPMI;
275 	dev->name = "IPMI controller";
276 	dev->device_data = data;
277 
278 	list_add_tail(&dev->list, &dmi_devices);
279 }
280 
281 static void __init dmi_save_dev_onboard(int instance, int segment, int bus,
282 					int devfn, const char *name)
283 {
284 	struct dmi_dev_onboard *onboard_dev;
285 
286 	onboard_dev = dmi_alloc(sizeof(*onboard_dev) + strlen(name) + 1);
287 	if (!onboard_dev) {
288 		printk(KERN_ERR "dmi_save_dev_onboard: out of memory.\n");
289 		return;
290 	}
291 	onboard_dev->instance = instance;
292 	onboard_dev->segment = segment;
293 	onboard_dev->bus = bus;
294 	onboard_dev->devfn = devfn;
295 
296 	strcpy((char *)&onboard_dev[1], name);
297 	onboard_dev->dev.type = DMI_DEV_TYPE_DEV_ONBOARD;
298 	onboard_dev->dev.name = (char *)&onboard_dev[1];
299 	onboard_dev->dev.device_data = onboard_dev;
300 
301 	list_add(&onboard_dev->dev.list, &dmi_devices);
302 }
303 
304 static void __init dmi_save_extended_devices(const struct dmi_header *dm)
305 {
306 	const u8 *d = (u8*) dm + 5;
307 
308 	/* Skip disabled device */
309 	if ((*d & 0x80) == 0)
310 		return;
311 
312 	dmi_save_dev_onboard(*(d+1), *(u16 *)(d+2), *(d+4), *(d+5),
313 			     dmi_string_nosave(dm, *(d-1)));
314 	dmi_save_one_device(*d & 0x7f, dmi_string_nosave(dm, *(d - 1)));
315 }
316 
317 /*
318  *	Process a DMI table entry. Right now all we care about are the BIOS
319  *	and machine entries. For 2.5 we should pull the smbus controller info
320  *	out of here.
321  */
322 static void __init dmi_decode(const struct dmi_header *dm, void *dummy)
323 {
324 	switch(dm->type) {
325 	case 0:		/* BIOS Information */
326 		dmi_save_ident(dm, DMI_BIOS_VENDOR, 4);
327 		dmi_save_ident(dm, DMI_BIOS_VERSION, 5);
328 		dmi_save_ident(dm, DMI_BIOS_DATE, 8);
329 		break;
330 	case 1:		/* System Information */
331 		dmi_save_ident(dm, DMI_SYS_VENDOR, 4);
332 		dmi_save_ident(dm, DMI_PRODUCT_NAME, 5);
333 		dmi_save_ident(dm, DMI_PRODUCT_VERSION, 6);
334 		dmi_save_ident(dm, DMI_PRODUCT_SERIAL, 7);
335 		dmi_save_uuid(dm, DMI_PRODUCT_UUID, 8);
336 		break;
337 	case 2:		/* Base Board Information */
338 		dmi_save_ident(dm, DMI_BOARD_VENDOR, 4);
339 		dmi_save_ident(dm, DMI_BOARD_NAME, 5);
340 		dmi_save_ident(dm, DMI_BOARD_VERSION, 6);
341 		dmi_save_ident(dm, DMI_BOARD_SERIAL, 7);
342 		dmi_save_ident(dm, DMI_BOARD_ASSET_TAG, 8);
343 		break;
344 	case 3:		/* Chassis Information */
345 		dmi_save_ident(dm, DMI_CHASSIS_VENDOR, 4);
346 		dmi_save_type(dm, DMI_CHASSIS_TYPE, 5);
347 		dmi_save_ident(dm, DMI_CHASSIS_VERSION, 6);
348 		dmi_save_ident(dm, DMI_CHASSIS_SERIAL, 7);
349 		dmi_save_ident(dm, DMI_CHASSIS_ASSET_TAG, 8);
350 		break;
351 	case 10:	/* Onboard Devices Information */
352 		dmi_save_devices(dm);
353 		break;
354 	case 11:	/* OEM Strings */
355 		dmi_save_oem_strings_devices(dm);
356 		break;
357 	case 38:	/* IPMI Device Information */
358 		dmi_save_ipmi_device(dm);
359 		break;
360 	case 41:	/* Onboard Devices Extended Information */
361 		dmi_save_extended_devices(dm);
362 	}
363 }
364 
365 static void __init print_filtered(const char *info)
366 {
367 	const char *p;
368 
369 	if (!info)
370 		return;
371 
372 	for (p = info; *p; p++)
373 		if (isprint(*p))
374 			printk(KERN_CONT "%c", *p);
375 		else
376 			printk(KERN_CONT "\\x%02x", *p & 0xff);
377 }
378 
379 static void __init dmi_dump_ids(void)
380 {
381 	printk(KERN_DEBUG "DMI: ");
382 	print_filtered(dmi_get_system_info(DMI_BOARD_NAME));
383 	printk(KERN_CONT "/");
384 	print_filtered(dmi_get_system_info(DMI_PRODUCT_NAME));
385 	printk(KERN_CONT ", BIOS ");
386 	print_filtered(dmi_get_system_info(DMI_BIOS_VERSION));
387 	printk(KERN_CONT " ");
388 	print_filtered(dmi_get_system_info(DMI_BIOS_DATE));
389 	printk(KERN_CONT "\n");
390 }
391 
392 static int __init dmi_present(const char __iomem *p)
393 {
394 	u8 buf[15];
395 
396 	memcpy_fromio(buf, p, 15);
397 	if ((memcmp(buf, "_DMI_", 5) == 0) && dmi_checksum(buf)) {
398 		dmi_num = (buf[13] << 8) | buf[12];
399 		dmi_len = (buf[7] << 8) | buf[6];
400 		dmi_base = (buf[11] << 24) | (buf[10] << 16) |
401 			(buf[9] << 8) | buf[8];
402 
403 		/*
404 		 * DMI version 0.0 means that the real version is taken from
405 		 * the SMBIOS version, which we don't know at this point.
406 		 */
407 		if (buf[14] != 0)
408 			printk(KERN_INFO "DMI %d.%d present.\n",
409 			       buf[14] >> 4, buf[14] & 0xF);
410 		else
411 			printk(KERN_INFO "DMI present.\n");
412 		if (dmi_walk_early(dmi_decode) == 0) {
413 			dmi_dump_ids();
414 			return 0;
415 		}
416 	}
417 	return 1;
418 }
419 
420 void __init dmi_scan_machine(void)
421 {
422 	char __iomem *p, *q;
423 	int rc;
424 
425 	if (efi_enabled) {
426 		if (efi.smbios == EFI_INVALID_TABLE_ADDR)
427 			goto error;
428 
429 		/* This is called as a core_initcall() because it isn't
430 		 * needed during early boot.  This also means we can
431 		 * iounmap the space when we're done with it.
432 		 */
433 		p = dmi_ioremap(efi.smbios, 32);
434 		if (p == NULL)
435 			goto error;
436 
437 		rc = dmi_present(p + 0x10); /* offset of _DMI_ string */
438 		dmi_iounmap(p, 32);
439 		if (!rc) {
440 			dmi_available = 1;
441 			goto out;
442 		}
443 	}
444 	else {
445 		/*
446 		 * no iounmap() for that ioremap(); it would be a no-op, but
447 		 * it's so early in setup that sucker gets confused into doing
448 		 * what it shouldn't if we actually call it.
449 		 */
450 		p = dmi_ioremap(0xF0000, 0x10000);
451 		if (p == NULL)
452 			goto error;
453 
454 		for (q = p; q < p + 0x10000; q += 16) {
455 			rc = dmi_present(q);
456 			if (!rc) {
457 				dmi_available = 1;
458 				dmi_iounmap(p, 0x10000);
459 				goto out;
460 			}
461 		}
462 		dmi_iounmap(p, 0x10000);
463 	}
464  error:
465 	printk(KERN_INFO "DMI not present or invalid.\n");
466  out:
467 	dmi_initialized = 1;
468 }
469 
470 /**
471  *	dmi_matches - check if dmi_system_id structure matches system DMI data
472  *	@dmi: pointer to the dmi_system_id structure to check
473  */
474 static bool dmi_matches(const struct dmi_system_id *dmi)
475 {
476 	int i;
477 
478 	WARN(!dmi_initialized, KERN_ERR "dmi check: not initialized yet.\n");
479 
480 	for (i = 0; i < ARRAY_SIZE(dmi->matches); i++) {
481 		int s = dmi->matches[i].slot;
482 		if (s == DMI_NONE)
483 			break;
484 		if (dmi_ident[s]
485 		    && strstr(dmi_ident[s], dmi->matches[i].substr))
486 			continue;
487 		/* No match */
488 		return false;
489 	}
490 	return true;
491 }
492 
493 /**
494  *	dmi_is_end_of_table - check for end-of-table marker
495  *	@dmi: pointer to the dmi_system_id structure to check
496  */
497 static bool dmi_is_end_of_table(const struct dmi_system_id *dmi)
498 {
499 	return dmi->matches[0].slot == DMI_NONE;
500 }
501 
502 /**
503  *	dmi_check_system - check system DMI data
504  *	@list: array of dmi_system_id structures to match against
505  *		All non-null elements of the list must match
506  *		their slot's (field index's) data (i.e., each
507  *		list string must be a substring of the specified
508  *		DMI slot's string data) to be considered a
509  *		successful match.
510  *
511  *	Walk the blacklist table running matching functions until someone
512  *	returns non zero or we hit the end. Callback function is called for
513  *	each successful match. Returns the number of matches.
514  */
515 int dmi_check_system(const struct dmi_system_id *list)
516 {
517 	int count = 0;
518 	const struct dmi_system_id *d;
519 
520 	for (d = list; !dmi_is_end_of_table(d); d++)
521 		if (dmi_matches(d)) {
522 			count++;
523 			if (d->callback && d->callback(d))
524 				break;
525 		}
526 
527 	return count;
528 }
529 EXPORT_SYMBOL(dmi_check_system);
530 
531 /**
532  *	dmi_first_match - find dmi_system_id structure matching system DMI data
533  *	@list: array of dmi_system_id structures to match against
534  *		All non-null elements of the list must match
535  *		their slot's (field index's) data (i.e., each
536  *		list string must be a substring of the specified
537  *		DMI slot's string data) to be considered a
538  *		successful match.
539  *
540  *	Walk the blacklist table until the first match is found.  Return the
541  *	pointer to the matching entry or NULL if there's no match.
542  */
543 const struct dmi_system_id *dmi_first_match(const struct dmi_system_id *list)
544 {
545 	const struct dmi_system_id *d;
546 
547 	for (d = list; !dmi_is_end_of_table(d); d++)
548 		if (dmi_matches(d))
549 			return d;
550 
551 	return NULL;
552 }
553 EXPORT_SYMBOL(dmi_first_match);
554 
555 /**
556  *	dmi_get_system_info - return DMI data value
557  *	@field: data index (see enum dmi_field)
558  *
559  *	Returns one DMI data value, can be used to perform
560  *	complex DMI data checks.
561  */
562 const char *dmi_get_system_info(int field)
563 {
564 	return dmi_ident[field];
565 }
566 EXPORT_SYMBOL(dmi_get_system_info);
567 
568 /**
569  * dmi_name_in_serial - Check if string is in the DMI product serial information
570  * @str: string to check for
571  */
572 int dmi_name_in_serial(const char *str)
573 {
574 	int f = DMI_PRODUCT_SERIAL;
575 	if (dmi_ident[f] && strstr(dmi_ident[f], str))
576 		return 1;
577 	return 0;
578 }
579 
580 /**
581  *	dmi_name_in_vendors - Check if string is anywhere in the DMI vendor information.
582  *	@str: 	Case sensitive Name
583  */
584 int dmi_name_in_vendors(const char *str)
585 {
586 	static int fields[] = { DMI_BIOS_VENDOR, DMI_BIOS_VERSION, DMI_SYS_VENDOR,
587 				DMI_PRODUCT_NAME, DMI_PRODUCT_VERSION, DMI_BOARD_VENDOR,
588 				DMI_BOARD_NAME, DMI_BOARD_VERSION, DMI_NONE };
589 	int i;
590 	for (i = 0; fields[i] != DMI_NONE; i++) {
591 		int f = fields[i];
592 		if (dmi_ident[f] && strstr(dmi_ident[f], str))
593 			return 1;
594 	}
595 	return 0;
596 }
597 EXPORT_SYMBOL(dmi_name_in_vendors);
598 
599 /**
600  *	dmi_find_device - find onboard device by type/name
601  *	@type: device type or %DMI_DEV_TYPE_ANY to match all device types
602  *	@name: device name string or %NULL to match all
603  *	@from: previous device found in search, or %NULL for new search.
604  *
605  *	Iterates through the list of known onboard devices. If a device is
606  *	found with a matching @vendor and @device, a pointer to its device
607  *	structure is returned.  Otherwise, %NULL is returned.
608  *	A new search is initiated by passing %NULL as the @from argument.
609  *	If @from is not %NULL, searches continue from next device.
610  */
611 const struct dmi_device * dmi_find_device(int type, const char *name,
612 				    const struct dmi_device *from)
613 {
614 	const struct list_head *head = from ? &from->list : &dmi_devices;
615 	struct list_head *d;
616 
617 	for(d = head->next; d != &dmi_devices; d = d->next) {
618 		const struct dmi_device *dev =
619 			list_entry(d, struct dmi_device, list);
620 
621 		if (((type == DMI_DEV_TYPE_ANY) || (dev->type == type)) &&
622 		    ((name == NULL) || (strcmp(dev->name, name) == 0)))
623 			return dev;
624 	}
625 
626 	return NULL;
627 }
628 EXPORT_SYMBOL(dmi_find_device);
629 
630 /**
631  *	dmi_get_date - parse a DMI date
632  *	@field:	data index (see enum dmi_field)
633  *	@yearp: optional out parameter for the year
634  *	@monthp: optional out parameter for the month
635  *	@dayp: optional out parameter for the day
636  *
637  *	The date field is assumed to be in the form resembling
638  *	[mm[/dd]]/yy[yy] and the result is stored in the out
639  *	parameters any or all of which can be omitted.
640  *
641  *	If the field doesn't exist, all out parameters are set to zero
642  *	and false is returned.  Otherwise, true is returned with any
643  *	invalid part of date set to zero.
644  *
645  *	On return, year, month and day are guaranteed to be in the
646  *	range of [0,9999], [0,12] and [0,31] respectively.
647  */
648 bool dmi_get_date(int field, int *yearp, int *monthp, int *dayp)
649 {
650 	int year = 0, month = 0, day = 0;
651 	bool exists;
652 	const char *s, *y;
653 	char *e;
654 
655 	s = dmi_get_system_info(field);
656 	exists = s;
657 	if (!exists)
658 		goto out;
659 
660 	/*
661 	 * Determine year first.  We assume the date string resembles
662 	 * mm/dd/yy[yy] but the original code extracted only the year
663 	 * from the end.  Keep the behavior in the spirit of no
664 	 * surprises.
665 	 */
666 	y = strrchr(s, '/');
667 	if (!y)
668 		goto out;
669 
670 	y++;
671 	year = simple_strtoul(y, &e, 10);
672 	if (y != e && year < 100) {	/* 2-digit year */
673 		year += 1900;
674 		if (year < 1996)	/* no dates < spec 1.0 */
675 			year += 100;
676 	}
677 	if (year > 9999)		/* year should fit in %04d */
678 		year = 0;
679 
680 	/* parse the mm and dd */
681 	month = simple_strtoul(s, &e, 10);
682 	if (s == e || *e != '/' || !month || month > 12) {
683 		month = 0;
684 		goto out;
685 	}
686 
687 	s = e + 1;
688 	day = simple_strtoul(s, &e, 10);
689 	if (s == y || s == e || *e != '/' || day > 31)
690 		day = 0;
691 out:
692 	if (yearp)
693 		*yearp = year;
694 	if (monthp)
695 		*monthp = month;
696 	if (dayp)
697 		*dayp = day;
698 	return exists;
699 }
700 EXPORT_SYMBOL(dmi_get_date);
701 
702 /**
703  *	dmi_walk - Walk the DMI table and get called back for every record
704  *	@decode: Callback function
705  *	@private_data: Private data to be passed to the callback function
706  *
707  *	Returns -1 when the DMI table can't be reached, 0 on success.
708  */
709 int dmi_walk(void (*decode)(const struct dmi_header *, void *),
710 	     void *private_data)
711 {
712 	u8 *buf;
713 
714 	if (!dmi_available)
715 		return -1;
716 
717 	buf = ioremap(dmi_base, dmi_len);
718 	if (buf == NULL)
719 		return -1;
720 
721 	dmi_table(buf, dmi_len, dmi_num, decode, private_data);
722 
723 	iounmap(buf);
724 	return 0;
725 }
726 EXPORT_SYMBOL_GPL(dmi_walk);
727 
728 /**
729  * dmi_match - compare a string to the dmi field (if exists)
730  * @f: DMI field identifier
731  * @str: string to compare the DMI field to
732  *
733  * Returns true if the requested field equals to the str (including NULL).
734  */
735 bool dmi_match(enum dmi_field f, const char *str)
736 {
737 	const char *info = dmi_get_system_info(f);
738 
739 	if (info == NULL || str == NULL)
740 		return info == str;
741 
742 	return !strcmp(info, str);
743 }
744 EXPORT_SYMBOL_GPL(dmi_match);
745