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