xref: /openbmc/linux/drivers/acpi/utils.c (revision 6774def6)
1 /*
2  *  acpi_utils.c - ACPI Utility Functions ($Revision: 10 $)
3  *
4  *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
5  *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
6  *
7  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
8  *
9  *  This program is free software; you can redistribute it and/or modify
10  *  it under the terms of the GNU General Public License as published by
11  *  the Free Software Foundation; either version 2 of the License, or (at
12  *  your option) any later version.
13  *
14  *  This program is distributed in the hope that it will be useful, but
15  *  WITHOUT ANY WARRANTY; without even the implied warranty of
16  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
17  *  General Public License for more details.
18  *
19  *  You should have received a copy of the GNU General Public License along
20  *  with this program; if not, write to the Free Software Foundation, Inc.,
21  *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
22  *
23  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
24  */
25 
26 #include <linux/kernel.h>
27 #include <linux/module.h>
28 #include <linux/slab.h>
29 #include <linux/init.h>
30 #include <linux/types.h>
31 #include <linux/hardirq.h>
32 #include <linux/acpi.h>
33 #include <linux/dynamic_debug.h>
34 
35 #include "internal.h"
36 
37 #define _COMPONENT		ACPI_BUS_COMPONENT
38 ACPI_MODULE_NAME("utils");
39 
40 /* --------------------------------------------------------------------------
41                             Object Evaluation Helpers
42    -------------------------------------------------------------------------- */
43 static void
44 acpi_util_eval_error(acpi_handle h, acpi_string p, acpi_status s)
45 {
46 #ifdef ACPI_DEBUG_OUTPUT
47 	char prefix[80] = {'\0'};
48 	struct acpi_buffer buffer = {sizeof(prefix), prefix};
49 	acpi_get_name(h, ACPI_FULL_PATHNAME, &buffer);
50 	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Evaluate [%s.%s]: %s\n",
51 		(char *) prefix, p, acpi_format_exception(s)));
52 #else
53 	return;
54 #endif
55 }
56 
57 acpi_status
58 acpi_extract_package(union acpi_object *package,
59 		     struct acpi_buffer *format, struct acpi_buffer *buffer)
60 {
61 	u32 size_required = 0;
62 	u32 tail_offset = 0;
63 	char *format_string = NULL;
64 	u32 format_count = 0;
65 	u32 i = 0;
66 	u8 *head = NULL;
67 	u8 *tail = NULL;
68 
69 
70 	if (!package || (package->type != ACPI_TYPE_PACKAGE)
71 	    || (package->package.count < 1)) {
72 		printk(KERN_WARNING PREFIX "Invalid package argument\n");
73 		return AE_BAD_PARAMETER;
74 	}
75 
76 	if (!format || !format->pointer || (format->length < 1)) {
77 		printk(KERN_WARNING PREFIX "Invalid format argument\n");
78 		return AE_BAD_PARAMETER;
79 	}
80 
81 	if (!buffer) {
82 		printk(KERN_WARNING PREFIX "Invalid buffer argument\n");
83 		return AE_BAD_PARAMETER;
84 	}
85 
86 	format_count = (format->length / sizeof(char)) - 1;
87 	if (format_count > package->package.count) {
88 		printk(KERN_WARNING PREFIX "Format specifies more objects [%d]"
89 			      " than exist in package [%d].\n",
90 			      format_count, package->package.count);
91 		return AE_BAD_DATA;
92 	}
93 
94 	format_string = format->pointer;
95 
96 	/*
97 	 * Calculate size_required.
98 	 */
99 	for (i = 0; i < format_count; i++) {
100 
101 		union acpi_object *element = &(package->package.elements[i]);
102 
103 		switch (element->type) {
104 
105 		case ACPI_TYPE_INTEGER:
106 			switch (format_string[i]) {
107 			case 'N':
108 				size_required += sizeof(u64);
109 				tail_offset += sizeof(u64);
110 				break;
111 			case 'S':
112 				size_required +=
113 				    sizeof(char *) + sizeof(u64) +
114 				    sizeof(char);
115 				tail_offset += sizeof(char *);
116 				break;
117 			default:
118 				printk(KERN_WARNING PREFIX "Invalid package element"
119 					      " [%d]: got number, expecting"
120 					      " [%c]\n",
121 					      i, format_string[i]);
122 				return AE_BAD_DATA;
123 				break;
124 			}
125 			break;
126 
127 		case ACPI_TYPE_STRING:
128 		case ACPI_TYPE_BUFFER:
129 			switch (format_string[i]) {
130 			case 'S':
131 				size_required +=
132 				    sizeof(char *) +
133 				    (element->string.length * sizeof(char)) +
134 				    sizeof(char);
135 				tail_offset += sizeof(char *);
136 				break;
137 			case 'B':
138 				size_required +=
139 				    sizeof(u8 *) +
140 				    (element->buffer.length * sizeof(u8));
141 				tail_offset += sizeof(u8 *);
142 				break;
143 			default:
144 				printk(KERN_WARNING PREFIX "Invalid package element"
145 					      " [%d] got string/buffer,"
146 					      " expecting [%c]\n",
147 					      i, format_string[i]);
148 				return AE_BAD_DATA;
149 				break;
150 			}
151 			break;
152 		case ACPI_TYPE_LOCAL_REFERENCE:
153 			switch (format_string[i]) {
154 			case 'R':
155 				size_required += sizeof(void *);
156 				tail_offset += sizeof(void *);
157 				break;
158 			default:
159 				printk(KERN_WARNING PREFIX "Invalid package element"
160 					      " [%d] got reference,"
161 					      " expecting [%c]\n",
162 					      i, format_string[i]);
163 				return AE_BAD_DATA;
164 				break;
165 			}
166 			break;
167 
168 		case ACPI_TYPE_PACKAGE:
169 		default:
170 			ACPI_DEBUG_PRINT((ACPI_DB_INFO,
171 					  "Found unsupported element at index=%d\n",
172 					  i));
173 			/* TBD: handle nested packages... */
174 			return AE_SUPPORT;
175 			break;
176 		}
177 	}
178 
179 	/*
180 	 * Validate output buffer.
181 	 */
182 	if (buffer->length == ACPI_ALLOCATE_BUFFER) {
183 		buffer->pointer = ACPI_ALLOCATE_ZEROED(size_required);
184 		if (!buffer->pointer)
185 			return AE_NO_MEMORY;
186 		buffer->length = size_required;
187 	} else {
188 		if (buffer->length < size_required) {
189 			buffer->length = size_required;
190 			return AE_BUFFER_OVERFLOW;
191 		} else if (buffer->length != size_required ||
192 			   !buffer->pointer) {
193 			return AE_BAD_PARAMETER;
194 		}
195 	}
196 
197 	head = buffer->pointer;
198 	tail = buffer->pointer + tail_offset;
199 
200 	/*
201 	 * Extract package data.
202 	 */
203 	for (i = 0; i < format_count; i++) {
204 
205 		u8 **pointer = NULL;
206 		union acpi_object *element = &(package->package.elements[i]);
207 
208 		if (!element) {
209 			return AE_BAD_DATA;
210 		}
211 
212 		switch (element->type) {
213 
214 		case ACPI_TYPE_INTEGER:
215 			switch (format_string[i]) {
216 			case 'N':
217 				*((u64 *) head) =
218 				    element->integer.value;
219 				head += sizeof(u64);
220 				break;
221 			case 'S':
222 				pointer = (u8 **) head;
223 				*pointer = tail;
224 				*((u64 *) tail) =
225 				    element->integer.value;
226 				head += sizeof(u64 *);
227 				tail += sizeof(u64);
228 				/* NULL terminate string */
229 				*tail = (char)0;
230 				tail += sizeof(char);
231 				break;
232 			default:
233 				/* Should never get here */
234 				break;
235 			}
236 			break;
237 
238 		case ACPI_TYPE_STRING:
239 		case ACPI_TYPE_BUFFER:
240 			switch (format_string[i]) {
241 			case 'S':
242 				pointer = (u8 **) head;
243 				*pointer = tail;
244 				memcpy(tail, element->string.pointer,
245 				       element->string.length);
246 				head += sizeof(char *);
247 				tail += element->string.length * sizeof(char);
248 				/* NULL terminate string */
249 				*tail = (char)0;
250 				tail += sizeof(char);
251 				break;
252 			case 'B':
253 				pointer = (u8 **) head;
254 				*pointer = tail;
255 				memcpy(tail, element->buffer.pointer,
256 				       element->buffer.length);
257 				head += sizeof(u8 *);
258 				tail += element->buffer.length * sizeof(u8);
259 				break;
260 			default:
261 				/* Should never get here */
262 				break;
263 			}
264 			break;
265 		case ACPI_TYPE_LOCAL_REFERENCE:
266 			switch (format_string[i]) {
267 			case 'R':
268 				*(void **)head =
269 				    (void *)element->reference.handle;
270 				head += sizeof(void *);
271 				break;
272 			default:
273 				/* Should never get here */
274 				break;
275 			}
276 			break;
277 		case ACPI_TYPE_PACKAGE:
278 			/* TBD: handle nested packages... */
279 		default:
280 			/* Should never get here */
281 			break;
282 		}
283 	}
284 
285 	return AE_OK;
286 }
287 
288 EXPORT_SYMBOL(acpi_extract_package);
289 
290 acpi_status
291 acpi_evaluate_integer(acpi_handle handle,
292 		      acpi_string pathname,
293 		      struct acpi_object_list *arguments, unsigned long long *data)
294 {
295 	acpi_status status = AE_OK;
296 	union acpi_object element;
297 	struct acpi_buffer buffer = { 0, NULL };
298 
299 	if (!data)
300 		return AE_BAD_PARAMETER;
301 
302 	buffer.length = sizeof(union acpi_object);
303 	buffer.pointer = &element;
304 	status = acpi_evaluate_object(handle, pathname, arguments, &buffer);
305 	if (ACPI_FAILURE(status)) {
306 		acpi_util_eval_error(handle, pathname, status);
307 		return status;
308 	}
309 
310 	if (element.type != ACPI_TYPE_INTEGER) {
311 		acpi_util_eval_error(handle, pathname, AE_BAD_DATA);
312 		return AE_BAD_DATA;
313 	}
314 
315 	*data = element.integer.value;
316 
317 	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Return value [%llu]\n", *data));
318 
319 	return AE_OK;
320 }
321 
322 EXPORT_SYMBOL(acpi_evaluate_integer);
323 
324 acpi_status
325 acpi_evaluate_reference(acpi_handle handle,
326 			acpi_string pathname,
327 			struct acpi_object_list *arguments,
328 			struct acpi_handle_list *list)
329 {
330 	acpi_status status = AE_OK;
331 	union acpi_object *package = NULL;
332 	union acpi_object *element = NULL;
333 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
334 	u32 i = 0;
335 
336 
337 	if (!list) {
338 		return AE_BAD_PARAMETER;
339 	}
340 
341 	/* Evaluate object. */
342 
343 	status = acpi_evaluate_object(handle, pathname, arguments, &buffer);
344 	if (ACPI_FAILURE(status))
345 		goto end;
346 
347 	package = buffer.pointer;
348 
349 	if ((buffer.length == 0) || !package) {
350 		printk(KERN_ERR PREFIX "No return object (len %X ptr %p)\n",
351 			    (unsigned)buffer.length, package);
352 		status = AE_BAD_DATA;
353 		acpi_util_eval_error(handle, pathname, status);
354 		goto end;
355 	}
356 	if (package->type != ACPI_TYPE_PACKAGE) {
357 		printk(KERN_ERR PREFIX "Expecting a [Package], found type %X\n",
358 			    package->type);
359 		status = AE_BAD_DATA;
360 		acpi_util_eval_error(handle, pathname, status);
361 		goto end;
362 	}
363 	if (!package->package.count) {
364 		printk(KERN_ERR PREFIX "[Package] has zero elements (%p)\n",
365 			    package);
366 		status = AE_BAD_DATA;
367 		acpi_util_eval_error(handle, pathname, status);
368 		goto end;
369 	}
370 
371 	if (package->package.count > ACPI_MAX_HANDLES) {
372 		return AE_NO_MEMORY;
373 	}
374 	list->count = package->package.count;
375 
376 	/* Extract package data. */
377 
378 	for (i = 0; i < list->count; i++) {
379 
380 		element = &(package->package.elements[i]);
381 
382 		if (element->type != ACPI_TYPE_LOCAL_REFERENCE) {
383 			status = AE_BAD_DATA;
384 			printk(KERN_ERR PREFIX
385 				    "Expecting a [Reference] package element, found type %X\n",
386 				    element->type);
387 			acpi_util_eval_error(handle, pathname, status);
388 			break;
389 		}
390 
391 		if (!element->reference.handle) {
392 			printk(KERN_WARNING PREFIX "Invalid reference in"
393 			       " package %s\n", pathname);
394 			status = AE_NULL_ENTRY;
395 			break;
396 		}
397 		/* Get the  acpi_handle. */
398 
399 		list->handles[i] = element->reference.handle;
400 		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found reference [%p]\n",
401 				  list->handles[i]));
402 	}
403 
404       end:
405 	if (ACPI_FAILURE(status)) {
406 		list->count = 0;
407 		//kfree(list->handles);
408 	}
409 
410 	kfree(buffer.pointer);
411 
412 	return status;
413 }
414 
415 EXPORT_SYMBOL(acpi_evaluate_reference);
416 
417 acpi_status
418 acpi_get_physical_device_location(acpi_handle handle, struct acpi_pld_info **pld)
419 {
420 	acpi_status status;
421 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
422 	union acpi_object *output;
423 
424 	status = acpi_evaluate_object(handle, "_PLD", NULL, &buffer);
425 
426 	if (ACPI_FAILURE(status))
427 		return status;
428 
429 	output = buffer.pointer;
430 
431 	if (!output || output->type != ACPI_TYPE_PACKAGE
432 	    || !output->package.count
433 	    || output->package.elements[0].type != ACPI_TYPE_BUFFER
434 	    || output->package.elements[0].buffer.length < ACPI_PLD_REV1_BUFFER_SIZE) {
435 		status = AE_TYPE;
436 		goto out;
437 	}
438 
439 	status = acpi_decode_pld_buffer(
440 			output->package.elements[0].buffer.pointer,
441 			output->package.elements[0].buffer.length,
442 			pld);
443 
444 out:
445 	kfree(buffer.pointer);
446 	return status;
447 }
448 EXPORT_SYMBOL(acpi_get_physical_device_location);
449 
450 /**
451  * acpi_evaluate_ost: Evaluate _OST for hotplug operations
452  * @handle: ACPI device handle
453  * @source_event: source event code
454  * @status_code: status code
455  * @status_buf: optional detailed information (NULL if none)
456  *
457  * Evaluate _OST for hotplug operations. All ACPI hotplug handlers
458  * must call this function when evaluating _OST for hotplug operations.
459  * When the platform does not support _OST, this function has no effect.
460  */
461 acpi_status
462 acpi_evaluate_ost(acpi_handle handle, u32 source_event, u32 status_code,
463 		  struct acpi_buffer *status_buf)
464 {
465 	union acpi_object params[3] = {
466 		{.type = ACPI_TYPE_INTEGER,},
467 		{.type = ACPI_TYPE_INTEGER,},
468 		{.type = ACPI_TYPE_BUFFER,}
469 	};
470 	struct acpi_object_list arg_list = {3, params};
471 
472 	params[0].integer.value = source_event;
473 	params[1].integer.value = status_code;
474 	if (status_buf != NULL) {
475 		params[2].buffer.pointer = status_buf->pointer;
476 		params[2].buffer.length = status_buf->length;
477 	} else {
478 		params[2].buffer.pointer = NULL;
479 		params[2].buffer.length = 0;
480 	}
481 
482 	return acpi_evaluate_object(handle, "_OST", &arg_list, NULL);
483 }
484 EXPORT_SYMBOL(acpi_evaluate_ost);
485 
486 /**
487  * acpi_handle_path: Return the object path of handle
488  *
489  * Caller must free the returned buffer
490  */
491 static char *acpi_handle_path(acpi_handle handle)
492 {
493 	struct acpi_buffer buffer = {
494 		.length = ACPI_ALLOCATE_BUFFER,
495 		.pointer = NULL
496 	};
497 
498 	if (in_interrupt() ||
499 	    acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer) != AE_OK)
500 		return NULL;
501 	return buffer.pointer;
502 }
503 
504 /**
505  * acpi_handle_printk: Print message with ACPI prefix and object path
506  *
507  * This function is called through acpi_handle_<level> macros and prints
508  * a message with ACPI prefix and object path.  This function acquires
509  * the global namespace mutex to obtain an object path.  In interrupt
510  * context, it shows the object path as <n/a>.
511  */
512 void
513 acpi_handle_printk(const char *level, acpi_handle handle, const char *fmt, ...)
514 {
515 	struct va_format vaf;
516 	va_list args;
517 	const char *path;
518 
519 	va_start(args, fmt);
520 	vaf.fmt = fmt;
521 	vaf.va = &args;
522 
523 	path = acpi_handle_path(handle);
524 	printk("%sACPI: %s: %pV", level, path ? path : "<n/a>" , &vaf);
525 
526 	va_end(args);
527 	kfree(path);
528 }
529 EXPORT_SYMBOL(acpi_handle_printk);
530 
531 #if defined(CONFIG_DYNAMIC_DEBUG)
532 /**
533  * __acpi_handle_debug: pr_debug with ACPI prefix and object path
534  *
535  * This function is called through acpi_handle_debug macro and debug
536  * prints a message with ACPI prefix and object path. This function
537  * acquires the global namespace mutex to obtain an object path.  In
538  * interrupt context, it shows the object path as <n/a>.
539  */
540 void
541 __acpi_handle_debug(struct _ddebug *descriptor, acpi_handle handle,
542 		    const char *fmt, ...)
543 {
544 	struct va_format vaf;
545 	va_list args;
546 	const char *path;
547 
548 	va_start(args, fmt);
549 	vaf.fmt = fmt;
550 	vaf.va = &args;
551 
552 	path = acpi_handle_path(handle);
553 	__dynamic_pr_debug(descriptor, "ACPI: %s: %pV", path ? path : "<n/a>", &vaf);
554 
555 	va_end(args);
556 	kfree(path);
557 }
558 EXPORT_SYMBOL(__acpi_handle_debug);
559 #endif
560 
561 /**
562  * acpi_has_method: Check whether @handle has a method named @name
563  * @handle: ACPI device handle
564  * @name: name of object or method
565  *
566  * Check whether @handle has a method named @name.
567  */
568 bool acpi_has_method(acpi_handle handle, char *name)
569 {
570 	acpi_handle tmp;
571 
572 	return ACPI_SUCCESS(acpi_get_handle(handle, name, &tmp));
573 }
574 EXPORT_SYMBOL(acpi_has_method);
575 
576 acpi_status acpi_execute_simple_method(acpi_handle handle, char *method,
577 				       u64 arg)
578 {
579 	union acpi_object obj = { .type = ACPI_TYPE_INTEGER };
580 	struct acpi_object_list arg_list = { .count = 1, .pointer = &obj, };
581 
582 	obj.integer.value = arg;
583 
584 	return acpi_evaluate_object(handle, method, &arg_list, NULL);
585 }
586 EXPORT_SYMBOL(acpi_execute_simple_method);
587 
588 /**
589  * acpi_evaluate_ej0: Evaluate _EJ0 method for hotplug operations
590  * @handle: ACPI device handle
591  *
592  * Evaluate device's _EJ0 method for hotplug operations.
593  */
594 acpi_status acpi_evaluate_ej0(acpi_handle handle)
595 {
596 	acpi_status status;
597 
598 	status = acpi_execute_simple_method(handle, "_EJ0", 1);
599 	if (status == AE_NOT_FOUND)
600 		acpi_handle_warn(handle, "No _EJ0 support for device\n");
601 	else if (ACPI_FAILURE(status))
602 		acpi_handle_warn(handle, "Eject failed (0x%x)\n", status);
603 
604 	return status;
605 }
606 
607 /**
608  * acpi_evaluate_lck: Evaluate _LCK method to lock/unlock device
609  * @handle: ACPI device handle
610  * @lock: lock device if non-zero, otherwise unlock device
611  *
612  * Evaluate device's _LCK method if present to lock/unlock device
613  */
614 acpi_status acpi_evaluate_lck(acpi_handle handle, int lock)
615 {
616 	acpi_status status;
617 
618 	status = acpi_execute_simple_method(handle, "_LCK", !!lock);
619 	if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
620 		if (lock)
621 			acpi_handle_warn(handle,
622 				"Locking device failed (0x%x)\n", status);
623 		else
624 			acpi_handle_warn(handle,
625 				"Unlocking device failed (0x%x)\n", status);
626 	}
627 
628 	return status;
629 }
630 
631 /**
632  * acpi_evaluate_dsm - evaluate device's _DSM method
633  * @handle: ACPI device handle
634  * @uuid: UUID of requested functions, should be 16 bytes
635  * @rev: revision number of requested function
636  * @func: requested function number
637  * @argv4: the function specific parameter
638  *
639  * Evaluate device's _DSM method with specified UUID, revision id and
640  * function number. Caller needs to free the returned object.
641  *
642  * Though ACPI defines the fourth parameter for _DSM should be a package,
643  * some old BIOSes do expect a buffer or an integer etc.
644  */
645 union acpi_object *
646 acpi_evaluate_dsm(acpi_handle handle, const u8 *uuid, int rev, int func,
647 		  union acpi_object *argv4)
648 {
649 	acpi_status ret;
650 	struct acpi_buffer buf = {ACPI_ALLOCATE_BUFFER, NULL};
651 	union acpi_object params[4];
652 	struct acpi_object_list input = {
653 		.count = 4,
654 		.pointer = params,
655 	};
656 
657 	params[0].type = ACPI_TYPE_BUFFER;
658 	params[0].buffer.length = 16;
659 	params[0].buffer.pointer = (char *)uuid;
660 	params[1].type = ACPI_TYPE_INTEGER;
661 	params[1].integer.value = rev;
662 	params[2].type = ACPI_TYPE_INTEGER;
663 	params[2].integer.value = func;
664 	if (argv4) {
665 		params[3] = *argv4;
666 	} else {
667 		params[3].type = ACPI_TYPE_PACKAGE;
668 		params[3].package.count = 0;
669 		params[3].package.elements = NULL;
670 	}
671 
672 	ret = acpi_evaluate_object(handle, "_DSM", &input, &buf);
673 	if (ACPI_SUCCESS(ret))
674 		return (union acpi_object *)buf.pointer;
675 
676 	if (ret != AE_NOT_FOUND)
677 		acpi_handle_warn(handle,
678 				"failed to evaluate _DSM (0x%x)\n", ret);
679 
680 	return NULL;
681 }
682 EXPORT_SYMBOL(acpi_evaluate_dsm);
683 
684 /**
685  * acpi_check_dsm - check if _DSM method supports requested functions.
686  * @handle: ACPI device handle
687  * @uuid: UUID of requested functions, should be 16 bytes at least
688  * @rev: revision number of requested functions
689  * @funcs: bitmap of requested functions
690  *
691  * Evaluate device's _DSM method to check whether it supports requested
692  * functions. Currently only support 64 functions at maximum, should be
693  * enough for now.
694  */
695 bool acpi_check_dsm(acpi_handle handle, const u8 *uuid, int rev, u64 funcs)
696 {
697 	int i;
698 	u64 mask = 0;
699 	union acpi_object *obj;
700 
701 	if (funcs == 0)
702 		return false;
703 
704 	obj = acpi_evaluate_dsm(handle, uuid, rev, 0, NULL);
705 	if (!obj)
706 		return false;
707 
708 	/* For compatibility, old BIOSes may return an integer */
709 	if (obj->type == ACPI_TYPE_INTEGER)
710 		mask = obj->integer.value;
711 	else if (obj->type == ACPI_TYPE_BUFFER)
712 		for (i = 0; i < obj->buffer.length && i < 8; i++)
713 			mask |= (((u8)obj->buffer.pointer[i]) << (i * 8));
714 	ACPI_FREE(obj);
715 
716 	/*
717 	 * Bit 0 indicates whether there's support for any functions other than
718 	 * function 0 for the specified UUID and revision.
719 	 */
720 	if ((mask & 0x1) && (mask & funcs) == funcs)
721 		return true;
722 
723 	return false;
724 }
725 EXPORT_SYMBOL(acpi_check_dsm);
726