xref: /netbsd/sys/dev/acpi/acpi.c (revision bf9ec67e)
1 /*	$NetBSD: acpi.c,v 1.7 2002/03/24 03:32:14 sommerfeld Exp $	*/
2 
3 /*
4  * Copyright 2001 Wasabi Systems, Inc.
5  * All rights reserved.
6  *
7  * Written by Jason R. Thorpe for Wasabi Systems, Inc.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in the
16  *    documentation and/or other materials provided with the distribution.
17  * 3. All advertising materials mentioning features or use of this software
18  *    must display the following acknowledgement:
19  *	This product includes software developed for the NetBSD Project by
20  *	Wasabi Systems, Inc.
21  * 4. The name of Wasabi Systems, Inc. may not be used to endorse
22  *    or promote products derived from this software without specific prior
23  *    written permission.
24  *
25  * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``AS IS'' AND
26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
27  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
28  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL WASABI SYSTEMS, INC
29  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
30  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
31  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
32  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
33  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
34  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
35  * POSSIBILITY OF SUCH DAMAGE.
36  */
37 
38 /*
39  * Autoconfiguration support for the Intel ACPI Component Architecture
40  * ACPI reference implementation.
41  */
42 
43 #include <sys/cdefs.h>
44 __KERNEL_RCSID(0, "$NetBSD: acpi.c,v 1.7 2002/03/24 03:32:14 sommerfeld Exp $");
45 
46 #include <sys/param.h>
47 #include <sys/systm.h>
48 #include <sys/device.h>
49 #include <sys/malloc.h>
50 
51 #include <dev/acpi/acpica.h>
52 #include <dev/acpi/acpireg.h>
53 #include <dev/acpi/acpivar.h>
54 #include <dev/acpi/acpi_osd.h>
55 
56 #ifdef ENABLE_DEBUGGER
57 #define	ACPI_DBGR_INIT		0x01
58 #define	ACPI_DBGR_TABLES	0x02
59 #define	ACPI_DBGR_ENABLE	0x04
60 #define	ACPI_DBGR_PROBE		0x08
61 #define	ACPI_DBGR_RUNNING	0x10
62 
63 int	acpi_dbgr = 0x00;
64 #endif
65 
66 int	acpi_match(struct device *, struct cfdata *, void *);
67 void	acpi_attach(struct device *, struct device *, void *);
68 
69 int	acpi_print(void *aux, const char *);
70 
71 extern struct cfdriver acpi_cd;
72 
73 struct cfattach acpi_ca = {
74 	sizeof(struct acpi_softc), acpi_match, acpi_attach,
75 };
76 
77 /*
78  * This is a flag we set when the ACPI subsystem is active.  Machine
79  * dependent code may wish to skip other steps (such as attaching
80  * subsystems that ACPI supercedes) when ACPI is active.
81  */
82 int	acpi_active;
83 
84 /*
85  * Pointer to the ACPI subsystem's state.  There can be only
86  * one ACPI instance.
87  */
88 struct acpi_softc *acpi_softc;
89 
90 void		acpi_shutdown(void *);
91 ACPI_STATUS	acpi_disable(struct acpi_softc *sc);
92 void		acpi_build_tree(struct acpi_softc *);
93 ACPI_STATUS	acpi_make_devnode(ACPI_HANDLE, UINT32, void *, void **);
94 
95 void		acpi_enable_fixed_events(struct acpi_softc *);
96 
97 /*
98  * acpi_probe:
99  *
100  *	Probe for ACPI support.  This is called by the
101  *	machine-dependent ACPI front-end.  All of the
102  *	actual work is done by ACPICA.
103  *
104  *	NOTE: This is not an autoconfiguration interface function.
105  */
106 int
107 acpi_probe(void)
108 {
109 	static int beenhere;
110 	ACPI_STATUS rv;
111 
112 	if (beenhere != 0)
113 		panic("acpi_probe: ACPI has already been probed");
114 	beenhere = 1;
115 
116 	/*
117 	 * Start up ACPICA.
118 	 */
119 #ifdef ENABLE_DEBUGGER
120 	if (acpi_dbgr & ACPI_DBGR_INIT)
121 		acpi_osd_debugger();
122 #endif
123 
124 	rv = AcpiInitializeSubsystem();
125 	if (rv != AE_OK) {
126 		printf("ACPI: unable to initialize ACPICA: %d\n", rv);
127 		return (0);
128 	}
129 
130 #ifdef ENABLE_DEBUGGER
131 	if (acpi_dbgr & ACPI_DBGR_TABLES)
132 		acpi_osd_debugger();
133 #endif
134 
135 	rv = AcpiLoadTables();
136 	if (rv != AE_OK) {
137 		printf("ACPI: unable to load tables: %d\n", rv);
138 		return (0);
139 	}
140 
141 	/*
142 	 * Looks like we have ACPI!
143 	 */
144 
145 	return (1);
146 }
147 
148 /*
149  * acpi_match:
150  *
151  *	Autoconfiguration `match' routine.
152  */
153 int
154 acpi_match(struct device *parent, struct cfdata *match, void *aux)
155 {
156 	struct acpibus_attach_args *aa = aux;
157 
158 	if (strcmp(aa->aa_busname, acpi_cd.cd_name) != 0)
159 		return (0);
160 
161 	/*
162 	 * XXX Check other locators?  Hard to know -- machine
163 	 * dependent code has already checked for the presence
164 	 * of ACPI by calling acpi_probe(), so I suppose we
165 	 * don't really have to do anything else.
166 	 */
167 	return (1);
168 }
169 
170 /*
171  * acpi_attach:
172  *
173  *	Autoconfiguration `attach' routine.  Finish initializing
174  *	ACPICA (some initialization was done in acpi_probe(),
175  *	which was required to check for the presence of ACPI),
176  *	and enable the ACPI subsystem.
177  */
178 void
179 acpi_attach(struct device *parent, struct device *self, void *aux)
180 {
181 	struct acpi_softc *sc = (void *) self;
182 	struct acpibus_attach_args *aa = aux;
183 	ACPI_STATUS rv;
184 
185 	printf("\n");
186 
187 	if (acpi_softc != NULL)
188 		panic("acpi_attach: ACPI has already been attached");
189 
190 	sc->sc_iot = aa->aa_iot;
191 	sc->sc_memt = aa->aa_memt;
192 	sc->sc_pc = aa->aa_pc;
193 	sc->sc_pciflags = aa->aa_pciflags;
194 
195 	acpi_softc = sc;
196 
197 	/*
198 	 * Install the default address space handlers.
199 	 */
200 
201 	rv = AcpiInstallAddressSpaceHandler(ACPI_ROOT_OBJECT,
202 	    ACPI_ADR_SPACE_SYSTEM_MEMORY, ACPI_DEFAULT_HANDLER, NULL, NULL);
203 	if (rv != AE_OK) {
204 		printf("%s: unable to install SYSTEM MEMORY handler: %d\n",
205 		    sc->sc_dev.dv_xname, rv);
206 		return;
207 	}
208 
209 	rv = AcpiInstallAddressSpaceHandler(ACPI_ROOT_OBJECT,
210 	    ACPI_ADR_SPACE_SYSTEM_IO, ACPI_DEFAULT_HANDLER, NULL, NULL);
211 	if (rv != AE_OK) {
212 		printf("%s: unable to install SYSTEM IO handler: %d\n",
213 		    sc->sc_dev.dv_xname, rv);
214 		return;
215 	}
216 
217 	rv = AcpiInstallAddressSpaceHandler(ACPI_ROOT_OBJECT,
218 	    ACPI_ADR_SPACE_PCI_CONFIG, ACPI_DEFAULT_HANDLER, NULL, NULL);
219 	if (rv != AE_OK) {
220 		printf("%s: unable to install PCI CONFIG handler: %d\n",
221 		    sc->sc_dev.dv_xname, rv);
222 		return;
223 	}
224 
225 	/*
226 	 * Bring ACPI on-line.
227 	 *
228 	 * Note that we request that _STA (device init) and _INI (object init)
229 	 * methods not be run.
230 	 *
231 	 * XXX We need to arrange for the object init pass after we have
232 	 * XXX attached all of our children.
233 	 */
234 #ifdef ENABLE_DEBUGGER
235 	if (acpi_dbgr & ACPI_DBGR_ENABLE)
236 		acpi_osd_debugger();
237 #endif
238 	rv = AcpiEnableSubsystem(ACPI_NO_DEVICE_INIT | ACPI_NO_OBJECT_INIT);
239 	if (rv != AE_OK) {
240 		printf("%s: unable to enable ACPI: %d\n",
241 		    sc->sc_dev.dv_xname, rv);
242 		return;
243 	}
244 	acpi_active = 1;
245 
246 	/*
247 	 * Set up the default sleep state to enter when various
248 	 * switches are activated.
249 	 */
250 	sc->sc_switch_sleep[ACPI_SWITCH_POWERBUTTON] = ACPI_STATE_S5;
251 	sc->sc_switch_sleep[ACPI_SWITCH_SLEEPBUTTON] = ACPI_STATE_S1;
252 	sc->sc_switch_sleep[ACPI_SWITCH_LID]	     = ACPI_STATE_S1;
253 
254 	/* Our current state is "awake". */
255 	sc->sc_sleepstate = ACPI_STATE_S0;
256 
257 	/*
258 	 * Check for fixed-hardware features.
259 	 */
260 	acpi_enable_fixed_events(sc);
261 
262 	/*
263 	 * Scan the namespace and build our device tree.
264 	 */
265 #ifdef ENABLE_DEBUGGER
266 	if (acpi_dbgr & ACPI_DBGR_PROBE)
267 		acpi_osd_debugger();
268 #endif
269 	acpi_build_tree(sc);
270 
271 	/*
272 	 * Register a shutdown hook that disables certain ACPI
273 	 * events that might happen and confuse us while we're
274 	 * trying to shut down.
275 	 */
276 	sc->sc_sdhook = shutdownhook_establish(acpi_shutdown, sc);
277 	if (sc->sc_sdhook == NULL)
278 		printf("%s: WARNING: unable to register shutdown hook\n",
279 		    sc->sc_dev.dv_xname);
280 
281 #ifdef ENABLE_DEBUGGER
282 	if (acpi_dbgr & ACPI_DBGR_RUNNING)
283 		acpi_osd_debugger();
284 #endif
285 }
286 
287 /*
288  * acpi_shutdown:
289  *
290  *	Shutdown hook for ACPI -- disable some events that
291  *	might confuse us.
292  */
293 void
294 acpi_shutdown(void *arg)
295 {
296 	struct acpi_softc *sc = arg;
297 
298 	if (acpi_disable(sc) != AE_OK)
299 		printf("%s: WARNING: unable to disable ACPI\n",
300 		    sc->sc_dev.dv_xname);
301 }
302 
303 /*
304  * acpi_disable:
305  *
306  *	Disable ACPI.
307  */
308 ACPI_STATUS
309 acpi_disable(struct acpi_softc *sc)
310 {
311 	ACPI_STATUS rv = AE_OK;
312 
313 	if (acpi_active) {
314 		rv = AcpiDisable();
315 		if (rv == AE_OK)
316 			acpi_active = 0;
317 	}
318 	return (rv);
319 }
320 
321 struct acpi_make_devnode_state {
322 	struct acpi_softc *softc;
323 	struct acpi_scope *scope;
324 };
325 
326 /*
327  * acpi_build_tree:
328  *
329  *	Scan relevant portions of the ACPI namespace and attach
330  *	child devices.
331  */
332 void
333 acpi_build_tree(struct acpi_softc *sc)
334 {
335 	static const char *scopes[] = {
336 		"\\_PR_",	/* ACPI 1.0 processor namespace */
337 		"\\_SB_",	/* system bus namespace */
338 		"\\_SI_",	/* system idicator namespace */
339 		"\\_TZ_",	/* ACPI 1.0 thermal zone namespace */
340 		NULL,
341 	};
342 	struct acpi_attach_args aa;
343 	struct acpi_make_devnode_state state;
344 	struct acpi_scope *as;
345 	struct acpi_devnode *ad;
346 	ACPI_HANDLE parent;
347 	int i;
348 
349 	TAILQ_INIT(&sc->sc_scopes);
350 
351 	state.softc = sc;
352 
353 	/*
354 	 * Scan the namespace and build our tree.
355 	 */
356 	for (i = 0; scopes[i] != NULL; i++) {
357 		as = malloc(sizeof(*as), M_DEVBUF, M_WAITOK);
358 		as->as_name = scopes[i];
359 		TAILQ_INIT(&as->as_devnodes);
360 
361 		TAILQ_INSERT_TAIL(&sc->sc_scopes, as, as_list);
362 
363 		state.scope = as;
364 
365 		if (AcpiGetHandle(ACPI_ROOT_OBJECT, (char *) scopes[i],
366 		    &parent) == AE_OK) {
367 			AcpiWalkNamespace(ACPI_TYPE_ANY, parent, 100,
368 			    acpi_make_devnode, &state, NULL);
369 		}
370 
371 		/* Now, for this namespace, try and attach the devices. */
372 		TAILQ_FOREACH(ad, &as->as_devnodes, ad_list) {
373 			aa.aa_node = ad;
374 			aa.aa_iot = sc->sc_iot;
375 			aa.aa_memt = sc->sc_memt;
376 			aa.aa_pc = sc->sc_pc;
377 			aa.aa_pciflags = sc->sc_pciflags;
378 
379 			/*
380 			 * XXX We only attach devices which are:
381 			 *
382 			 *	- present
383 			 *	- enabled
384 			 *	- to be shown
385 			 *	- functioning properly
386 			 *
387 			 * However, if enabled, it's decoding resources,
388 			 * so we should claim them, if possible.  Requires
389 			 * changes to bus_space(9).
390 			 */
391 			if ((ad->ad_devinfo.CurrentStatus &
392 			     (ACPI_STA_DEV_PRESENT|ACPI_STA_DEV_ENABLED|
393 			      ACPI_STA_DEV_SHOW|ACPI_STA_DEV_OK)) !=
394 			    (ACPI_STA_DEV_PRESENT|ACPI_STA_DEV_ENABLED|
395 			     ACPI_STA_DEV_SHOW|ACPI_STA_DEV_OK))
396 				continue;
397 
398 			/*
399 			 * XXX Same problem as above...
400 			 */
401 			if ((ad->ad_devinfo.Valid & ACPI_VALID_HID) == 0)
402 				continue;
403 
404 			ad->ad_device = config_found(&sc->sc_dev,
405 			    &aa, acpi_print);
406 		}
407 	}
408 }
409 
410 /*
411  * acpi_make_devnode:
412  *
413  *	Make an ACPI devnode.
414  */
415 ACPI_STATUS
416 acpi_make_devnode(ACPI_HANDLE handle, UINT32 level, void *context,
417     void **status)
418 {
419 	struct acpi_make_devnode_state *state = context;
420 #ifdef ACPI_DEBUG
421 	struct acpi_softc *sc = state->softc;
422 #endif
423 	struct acpi_scope *as = state->scope;
424 	struct acpi_devnode *ad;
425 	ACPI_OBJECT_TYPE type;
426 	ACPI_STATUS rv;
427 
428 	if (AcpiGetType(handle, &type) == AE_OK) {
429 		switch (type) {
430 		case ACPI_TYPE_DEVICE:
431 		case ACPI_TYPE_PROCESSOR:
432 		case ACPI_TYPE_THERMAL:
433 		case ACPI_TYPE_POWER:
434 			ad = malloc(sizeof(*ad), M_DEVBUF, M_NOWAIT|M_ZERO);
435 			if (ad == NULL)
436 				return (AE_NO_MEMORY);
437 
438 			ad->ad_handle = handle;
439 			ad->ad_level = level;
440 			ad->ad_scope = as;
441 			ad->ad_type = type;
442 
443 			TAILQ_INSERT_TAIL(&as->as_devnodes, ad, ad_list);
444 
445 			rv = AcpiGetObjectInfo(handle, &ad->ad_devinfo);
446 			if (rv != AE_OK)
447 				goto out;
448 
449 			if ((ad->ad_devinfo.Valid & ACPI_VALID_HID) == 0)
450 				goto out;
451 
452 #ifdef ACPI_DEBUG
453 			printf("%s: HID %s found in scope %s level %d\n",
454 			    sc->sc_dev.dv_xname, ad->ad_devinfo.HardwareId,
455 			    as->as_name, ad->ad_level);
456 			if (ad->ad_devinfo.Valid & ACPI_VALID_UID)
457 				printf("       UID %s\n",
458 				    ad->ad_devinfo.UniqueId);
459 			if (ad->ad_devinfo.Valid & ACPI_VALID_ADR)
460 				printf("       ADR 0x%016qx\n",
461 				    ad->ad_devinfo.Address);
462 			if (ad->ad_devinfo.Valid & ACPI_VALID_STA)
463 				printf("       STA 0x%08x\n",
464 				    ad->ad_devinfo.CurrentStatus);
465 #endif
466 		}
467 	}
468  out:
469 	return (AE_OK);
470 }
471 
472 /*
473  * acpi_print:
474  *
475  *	Autoconfiguration print routine.
476  */
477 int
478 acpi_print(void *aux, const char *pnp)
479 {
480 	struct acpi_attach_args *aa = aux;
481 #if 0
482 	char *str;
483 #endif
484 
485 	if (pnp) {
486 		printf("%s ", aa->aa_node->ad_devinfo.HardwareId);
487 #if 0 /* Not until we fix acpi_eval_string */
488 		if (acpi_eval_string(aa->aa_node->ad_handle,
489 		    "_STR", &str) == AE_OK) {
490 			printf("[%s] ", str);
491 			AcpiOsFree(str);
492 		}
493 #endif
494 		printf("at %s", pnp);
495 	}
496 
497 	return (UNCONF);
498 }
499 
500 /*****************************************************************************
501  * ACPI fixed-hardware feature handlers
502  *****************************************************************************/
503 
504 UINT32		acpi_fixed_power_button_handler(void *);
505 UINT32		acpi_fixed_sleep_button_handler(void *);
506 
507 /*
508  * acpi_enable_fixed_events:
509  *
510  *	Enable any fixed-hardware feature handlers.
511  */
512 void
513 acpi_enable_fixed_events(struct acpi_softc *sc)
514 {
515 	static int beenhere;
516 	ACPI_STATUS rv;
517 
518 	/*
519 	 * Check for fixed-hardware buttons.
520 	 */
521 
522 	if (AcpiGbl_FADT != NULL && AcpiGbl_FADT->PwrButton == 0) {
523 		if (beenhere == 0)
524 			printf("%s: fixed-feature power button present\n",
525 			    sc->sc_dev.dv_xname);
526 		rv = AcpiInstallFixedEventHandler(ACPI_EVENT_POWER_BUTTON,
527 		    acpi_fixed_power_button_handler, sc);
528 		if (rv != AE_OK)
529 			printf("%s: unable to install handler for fixed "
530 			    "power button: %d\n", sc->sc_dev.dv_xname, rv);
531 	}
532 
533 	if (AcpiGbl_FADT != NULL && AcpiGbl_FADT->SleepButton == 0) {
534 		if (beenhere == 0)
535 			printf("%s: fixed-feature sleep button present\n",
536 			    sc->sc_dev.dv_xname);
537 		rv = AcpiInstallFixedEventHandler(ACPI_EVENT_SLEEP_BUTTON,
538 		    acpi_fixed_sleep_button_handler, sc);
539 		if (rv != AE_OK)
540 			printf("%s: unable to install handler for fixed "
541 			    "power button: %d\n", sc->sc_dev.dv_xname, rv);
542 	}
543 
544 	beenhere = 1;
545 }
546 
547 /*
548  * acpi_fixed_power_button_handler:
549  *
550  *	Fixed event handler for the power button.
551  */
552 UINT32
553 acpi_fixed_power_button_handler(void *context)
554 {
555 	struct acpi_softc *sc = context;
556 
557 	/* XXX XXX XXX */
558 
559 	printf("%s: fixed power button pressed\n", sc->sc_dev.dv_xname);
560 
561 	return (INTERRUPT_HANDLED);
562 }
563 
564 /*
565  * acpi_fixed_sleep_button_handler:
566  *
567  *	Fixed event handler for the sleep button.
568  */
569 UINT32
570 acpi_fixed_sleep_button_handler(void *context)
571 {
572 	struct acpi_softc *sc = context;
573 
574 	/* XXX XXX XXX */
575 
576 	printf("%s: fixed sleep button pressed\n", sc->sc_dev.dv_xname);
577 
578 	return (INTERRUPT_HANDLED);
579 }
580 
581 /*****************************************************************************
582  * ACPI utility routines.
583  *****************************************************************************/
584 
585 /*
586  * acpi_eval_integer:
587  *
588  *	Evaluate an integer object.
589  */
590 ACPI_STATUS
591 acpi_eval_integer(ACPI_HANDLE handle, char *path, int *valp)
592 {
593 	ACPI_STATUS rv;
594 	ACPI_BUFFER buf;
595 	ACPI_OBJECT param;
596 
597 	if (handle == NULL)
598 		handle = ACPI_ROOT_OBJECT;
599 
600 	buf.Pointer = &param;
601 	buf.Length = sizeof(param);
602 
603 	rv = AcpiEvaluateObject(handle, path, NULL, &buf);
604 	if (rv == AE_OK) {
605 		if (param.Type == ACPI_TYPE_INTEGER)
606 			*valp = param.Integer.Value;
607 		else
608 			rv = AE_TYPE;
609 	}
610 
611 	return (rv);
612 }
613 
614 #if 0
615 /*
616  * acpi_eval_string:
617  *
618  *	Evaluate a (Unicode) string object.
619  * XXX current API may leak memory, so don't use this.
620  */
621 ACPI_STATUS
622 acpi_eval_string(ACPI_HANDLE handle, char *path, char **stringp)
623 {
624 	ACPI_STATUS rv;
625 	ACPI_BUFFER buf;
626 	ACPI_OBJECT *param;
627 
628 	if (handle == NULL)
629 		handle = ACPI_ROOT_OBJECT;
630 
631 	buf.Pointer = NULL;
632 	buf.Length = 0;
633 
634 	rv = AcpiEvaluateObject(handle, path, NULL, &buf);
635 	if (rv != AE_BUFFER_OVERFLOW)
636 		return (rv);
637 
638 	buf.Pointer = AcpiOsAllocate(buf.Length);
639 	if (buf.Pointer == NULL)
640 		return (AE_NO_MEMORY);
641 
642 	rv = AcpiEvaluateObject(handle, path, NULL, &buf);
643 	param = (ACPI_OBJECT *)buf.Pointer;
644 	if (rv == AE_OK) {
645 		if (param->Type == ACPI_TYPE_STRING) {
646 			/* XXX may leak buf.Pointer!! */
647 			*stringp = param->String.Pointer;
648 			return (AE_OK);
649 		}
650 		rv = AE_TYPE;
651 	}
652 
653 	AcpiOsFree(buf.Pointer);
654 	return (rv);
655 }
656 #endif
657 
658 
659 /*
660  * acpi_eval_struct:
661  *
662  *	Evaluate a more complex structure.  Caller must free buf.Pointer.
663  */
664 ACPI_STATUS
665 acpi_eval_struct(ACPI_HANDLE handle, char *path, ACPI_BUFFER *bufp)
666 {
667 	ACPI_STATUS rv;
668 
669 	if (handle == NULL)
670 		handle = ACPI_ROOT_OBJECT;
671 
672 	bufp->Pointer = NULL;
673 	bufp->Length = 0;
674 
675 	rv = AcpiEvaluateObject(handle, path, NULL, bufp);
676 	if (rv != AE_BUFFER_OVERFLOW)
677 		return (rv);
678 
679 	bufp->Pointer = AcpiOsAllocate(bufp->Length);
680 	if (bufp->Pointer == NULL)
681 		return (AE_NO_MEMORY);
682 
683 	rv = AcpiEvaluateObject(handle, path, NULL, bufp);
684 
685 	return (rv);
686 }
687 
688 /*
689  * acpi_get:
690  *
691  *	Fetch data info the specified (empty) ACPI buffer.
692  */
693 ACPI_STATUS
694 acpi_get(ACPI_HANDLE handle, ACPI_BUFFER *buf,
695     ACPI_STATUS (*getit)(ACPI_HANDLE, ACPI_BUFFER *))
696 {
697 	ACPI_STATUS rv;
698 
699 	buf->Pointer = NULL;
700 	buf->Length = 0;
701 
702 	rv = (*getit)(handle, buf);
703 	if (rv != AE_BUFFER_OVERFLOW)
704 		return (rv);
705 
706 	buf->Pointer = AcpiOsCallocate(buf->Length);
707 	if (buf->Pointer == NULL)
708 		return (AE_NO_MEMORY);
709 
710 	return ((*getit)(handle, buf));
711 }
712