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acpi.c revision 1.4.2.2
      1 /*	$NetBSD: acpi.c,v 1.4.2.2 2001/10/01 12:44:14 fvdl 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/param.h>
     44 #include <sys/systm.h>
     45 #include <sys/device.h>
     46 #include <sys/malloc.h>
     47 
     48 #include <dev/acpi/acpica.h>
     49 #include <dev/acpi/acpireg.h>
     50 #include <dev/acpi/acpivar.h>
     51 #include <dev/acpi/acpi_osd.h>
     52 
     53 #ifdef ENABLE_DEBUGGER
     54 #define	ACPI_DBGR_INIT		0x01
     55 #define	ACPI_DBGR_TABLES	0x02
     56 #define	ACPI_DBGR_ENABLE	0x04
     57 #define	ACPI_DBGR_PROBE		0x08
     58 #define	ACPI_DBGR_RUNNING	0x10
     59 
     60 int	acpi_dbgr = 0x00;
     61 #endif
     62 
     63 int	acpi_match(struct device *, struct cfdata *, void *);
     64 void	acpi_attach(struct device *, struct device *, void *);
     65 
     66 int	acpi_print(void *aux, const char *);
     67 
     68 extern struct cfdriver acpi_cd;
     69 
     70 struct cfattach acpi_ca = {
     71 	sizeof(struct acpi_softc), acpi_match, acpi_attach,
     72 };
     73 
     74 /*
     75  * This is a flag we set when the ACPI subsystem is active.  Machine
     76  * dependent code may wish to skip other steps (such as attaching
     77  * subsystems that ACPI supercedes) when ACPI is active.
     78  */
     79 int	acpi_active;
     80 
     81 /*
     82  * Pointer to the ACPI subsystem's state.  There can be only
     83  * one ACPI instance.
     84  */
     85 struct acpi_softc *acpi_softc;
     86 
     87 void		acpi_shutdown(void *);
     88 ACPI_STATUS	acpi_disable(struct acpi_softc *sc);
     89 void		acpi_build_tree(struct acpi_softc *);
     90 ACPI_STATUS	acpi_make_devnode(ACPI_HANDLE, UINT32, void *, void **);
     91 
     92 void		acpi_enable_fixed_events(struct acpi_softc *);
     93 
     94 /*
     95  * acpi_probe:
     96  *
     97  *	Probe for ACPI support.  This is called by the
     98  *	machine-dependent ACPI front-end.  All of the
     99  *	actual work is done by ACPICA.
    100  *
    101  *	NOTE: This is not an autoconfiguration interface function.
    102  */
    103 int
    104 acpi_probe(void)
    105 {
    106 	static int beenhere;
    107 	ACPI_STATUS rv;
    108 
    109 	if (beenhere != 0)
    110 		panic("acpi_probe: ACPI has already been probed");
    111 	beenhere = 1;
    112 
    113 	/*
    114 	 * Start up ACPICA.
    115 	 */
    116 #ifdef ENABLE_DEBUGGER
    117 	if (acpi_dbgr & ACPI_DBGR_INIT)
    118 		acpi_osd_debugger();
    119 #endif
    120 
    121 	rv = AcpiInitializeSubsystem();
    122 	if (rv != AE_OK) {
    123 		printf("ACPI: unable to initialize ACPICA: %d\n", rv);
    124 		return (0);
    125 	}
    126 
    127 #ifdef ENABLE_DEBUGGER
    128 	if (acpi_dbgr & ACPI_DBGR_TABLES)
    129 		acpi_osd_debugger();
    130 #endif
    131 
    132 	rv = AcpiLoadTables();
    133 	if (rv != AE_OK) {
    134 		printf("ACPI: unable to load tables: %d\n", rv);
    135 		return (0);
    136 	}
    137 
    138 	/*
    139 	 * Looks like we have ACPI!
    140 	 */
    141 
    142 	return (1);
    143 }
    144 
    145 /*
    146  * acpi_match:
    147  *
    148  *	Autoconfiguration `match' routine.
    149  */
    150 int
    151 acpi_match(struct device *parent, struct cfdata *match, void *aux)
    152 {
    153 	struct acpibus_attach_args *aa = aux;
    154 
    155 	if (strcmp(aa->aa_busname, acpi_cd.cd_name) != 0)
    156 		return (0);
    157 
    158 	/*
    159 	 * XXX Check other locators?  Hard to know -- machine
    160 	 * dependent code has already checked for the presence
    161 	 * of ACPI by calling acpi_probe(), so I suppose we
    162 	 * don't really have to do anything else.
    163 	 */
    164 	return (1);
    165 }
    166 
    167 /*
    168  * acpi_attach:
    169  *
    170  *	Autoconfiguration `attach' routine.  Finish initializing
    171  *	ACPICA (some initialization was done in acpi_probe(),
    172  *	which was required to check for the presence of ACPI),
    173  *	and enable the ACPI subsystem.
    174  */
    175 void
    176 acpi_attach(struct device *parent, struct device *self, void *aux)
    177 {
    178 	struct acpi_softc *sc = (void *) self;
    179 	struct acpibus_attach_args *aa = aux;
    180 	ACPI_STATUS rv;
    181 
    182 	printf("\n");
    183 
    184 	if (acpi_softc != NULL)
    185 		panic("acpi_attach: ACPI has already been attached");
    186 
    187 	sc->sc_iot = aa->aa_iot;
    188 	sc->sc_memt = aa->aa_memt;
    189 	sc->sc_pc = aa->aa_pc;
    190 	sc->sc_pciflags = aa->aa_pciflags;
    191 
    192 	acpi_softc = sc;
    193 
    194 	/*
    195 	 * Install the default address space handlers.
    196 	 */
    197 
    198 	rv = AcpiInstallAddressSpaceHandler(ACPI_ROOT_OBJECT,
    199 	    ACPI_ADR_SPACE_SYSTEM_MEMORY, ACPI_DEFAULT_HANDLER, NULL, NULL);
    200 	if (rv != AE_OK) {
    201 		printf("%s: unable to install SYSTEM MEMORY handler: %d\n",
    202 		    sc->sc_dev.dv_xname, rv);
    203 		return;
    204 	}
    205 
    206 	rv = AcpiInstallAddressSpaceHandler(ACPI_ROOT_OBJECT,
    207 	    ACPI_ADR_SPACE_SYSTEM_IO, ACPI_DEFAULT_HANDLER, NULL, NULL);
    208 	if (rv != AE_OK) {
    209 		printf("%s: unable to install SYSTEM IO handler: %d\n",
    210 		    sc->sc_dev.dv_xname, rv);
    211 		return;
    212 	}
    213 
    214 	rv = AcpiInstallAddressSpaceHandler(ACPI_ROOT_OBJECT,
    215 	    ACPI_ADR_SPACE_PCI_CONFIG, ACPI_DEFAULT_HANDLER, NULL, NULL);
    216 	if (rv != AE_OK) {
    217 		printf("%s: unable to install PCI CONFIG handler: %d\n",
    218 		    sc->sc_dev.dv_xname, rv);
    219 		return;
    220 	}
    221 
    222 	/*
    223 	 * Bring ACPI on-line.
    224 	 *
    225 	 * Note that we request that _STA (device init) and _INI (object init)
    226 	 * methods not be run.
    227 	 *
    228 	 * XXX We need to arrange for the object init pass after we have
    229 	 * XXX attached all of our children.
    230 	 */
    231 #ifdef ENABLE_DEBUGGER
    232 	if (acpi_dbgr & ACPI_DBGR_ENABLE)
    233 		acpi_osd_debugger();
    234 #endif
    235 	rv = AcpiEnableSubsystem(ACPI_NO_DEVICE_INIT | ACPI_NO_OBJECT_INIT);
    236 	if (rv != AE_OK) {
    237 		printf("%s: unable to enable ACPI: %d\n",
    238 		    sc->sc_dev.dv_xname, rv);
    239 		return;
    240 	}
    241 	acpi_active = 1;
    242 
    243 	/*
    244 	 * Set up the default sleep state to enter when various
    245 	 * switches are activated.
    246 	 */
    247 	sc->sc_switch_sleep[ACPI_SWITCH_POWERBUTTON] = ACPI_STATE_S5;
    248 	sc->sc_switch_sleep[ACPI_SWITCH_SLEEPBUTTON] = ACPI_STATE_S1;
    249 	sc->sc_switch_sleep[ACPI_SWITCH_LID]	     = ACPI_STATE_S1;
    250 
    251 	/* Our current state is "awake". */
    252 	sc->sc_sleepstate = ACPI_STATE_S0;
    253 
    254 	/*
    255 	 * Check for fixed-hardware features.
    256 	 */
    257 	acpi_enable_fixed_events(sc);
    258 
    259 	/*
    260 	 * Scan the namespace and build our device tree.
    261 	 */
    262 #ifdef ENABLE_DEBUGGER
    263 	if (acpi_dbgr & ACPI_DBGR_PROBE)
    264 		acpi_osd_debugger();
    265 #endif
    266 	acpi_build_tree(sc);
    267 
    268 	/*
    269 	 * Register a shutdown hook that disables certain ACPI
    270 	 * events that might happen and confuse us while we're
    271 	 * trying to shut down.
    272 	 */
    273 	sc->sc_sdhook = shutdownhook_establish(acpi_shutdown, sc);
    274 	if (sc->sc_sdhook == NULL)
    275 		printf("%s: WARNING: unable to register shutdown hook\n",
    276 		    sc->sc_dev.dv_xname);
    277 
    278 #ifdef ENABLE_DEBUGGER
    279 	if (acpi_dbgr & ACPI_DBGR_RUNNING)
    280 		acpi_osd_debugger();
    281 #endif
    282 }
    283 
    284 /*
    285  * acpi_shutdown:
    286  *
    287  *	Shutdown hook for ACPI -- disable some events that
    288  *	might confuse us.
    289  */
    290 void
    291 acpi_shutdown(void *arg)
    292 {
    293 	struct acpi_softc *sc = arg;
    294 
    295 	if (acpi_disable(sc) != AE_OK)
    296 		printf("%s: WARNING: unable to disable ACPI\n",
    297 		    sc->sc_dev.dv_xname);
    298 }
    299 
    300 /*
    301  * acpi_disable:
    302  *
    303  *	Disable ACPI.
    304  */
    305 ACPI_STATUS
    306 acpi_disable(struct acpi_softc *sc)
    307 {
    308 	ACPI_STATUS rv = AE_OK;
    309 
    310 	if (acpi_active) {
    311 		rv = AcpiDisable();
    312 		if (rv == AE_OK)
    313 			acpi_active = 0;
    314 	}
    315 	return (rv);
    316 }
    317 
    318 struct acpi_make_devnode_state {
    319 	struct acpi_softc *softc;
    320 	struct acpi_scope *scope;
    321 };
    322 
    323 /*
    324  * acpi_build_tree:
    325  *
    326  *	Scan relevant portions of the ACPI namespace and attach
    327  *	child devices.
    328  */
    329 void
    330 acpi_build_tree(struct acpi_softc *sc)
    331 {
    332 	static const char *scopes[] = {
    333 		"\\_PR_",	/* ACPI 1.0 processor namespace */
    334 		"\\_SB_",	/* system bus namespace */
    335 		"\\_SI_",	/* system idicator namespace */
    336 		"\\_TZ_",	/* ACPI 1.0 thermal zone namespace */
    337 		NULL,
    338 	};
    339 	struct acpi_attach_args aa;
    340 	struct acpi_make_devnode_state state;
    341 	struct acpi_scope *as;
    342 	struct acpi_devnode *ad;
    343 	ACPI_HANDLE parent;
    344 	int i;
    345 
    346 	TAILQ_INIT(&sc->sc_scopes);
    347 
    348 	state.softc = sc;
    349 
    350 	/*
    351 	 * Scan the namespace and build our tree.
    352 	 */
    353 	for (i = 0; scopes[i] != NULL; i++) {
    354 		as = malloc(sizeof(*as), M_DEVBUF, M_WAITOK);
    355 		as->as_name = scopes[i];
    356 		TAILQ_INIT(&as->as_devnodes);
    357 
    358 		TAILQ_INSERT_TAIL(&sc->sc_scopes, as, as_list);
    359 
    360 		state.scope = as;
    361 
    362 		if (AcpiGetHandle(ACPI_ROOT_OBJECT, (char *) scopes[i],
    363 		    &parent) == AE_OK) {
    364 			AcpiWalkNamespace(ACPI_TYPE_ANY, parent, 100,
    365 			    acpi_make_devnode, &state, NULL);
    366 		}
    367 
    368 		/* Now, for this namespace, try and attach the devices. */
    369 		TAILQ_FOREACH(ad, &as->as_devnodes, ad_list) {
    370 			aa.aa_node = ad;
    371 			aa.aa_iot = sc->sc_iot;
    372 			aa.aa_memt = sc->sc_memt;
    373 			aa.aa_pc = sc->sc_pc;
    374 			aa.aa_pciflags = sc->sc_pciflags;
    375 
    376 			/*
    377 			 * XXX We only attach devices which are:
    378 			 *
    379 			 *	- present
    380 			 *	- enabled
    381 			 *	- to be shown
    382 			 *	- functioning properly
    383 			 *
    384 			 * However, if enabled, it's decoding resources,
    385 			 * so we should claim them, if possible.  Requires
    386 			 * changes to bus_space(9).
    387 			 */
    388 			if ((ad->ad_devinfo.CurrentStatus &
    389 			     (ACPI_STA_DEV_PRESENT|ACPI_STA_DEV_ENABLED|
    390 			      ACPI_STA_DEV_SHOW|ACPI_STA_DEV_OK)) !=
    391 			    (ACPI_STA_DEV_PRESENT|ACPI_STA_DEV_ENABLED|
    392 			     ACPI_STA_DEV_SHOW|ACPI_STA_DEV_OK))
    393 				continue;
    394 
    395 			/*
    396 			 * XXX Same problem as above...
    397 			 */
    398 			if ((ad->ad_devinfo.Valid & ACPI_VALID_HID) == 0)
    399 				continue;
    400 
    401 			ad->ad_device = config_found(&sc->sc_dev,
    402 			    &aa, acpi_print);
    403 		}
    404 	}
    405 }
    406 
    407 /*
    408  * acpi_make_devnode:
    409  *
    410  *	Make an ACPI devnode.
    411  */
    412 ACPI_STATUS
    413 acpi_make_devnode(ACPI_HANDLE handle, UINT32 level, void *context,
    414     void **status)
    415 {
    416 	struct acpi_make_devnode_state *state = context;
    417 #ifdef ACPI_DEBUG
    418 	struct acpi_softc *sc = state->softc;
    419 #endif
    420 	struct acpi_scope *as = state->scope;
    421 	struct acpi_devnode *ad;
    422 	ACPI_OBJECT_TYPE type;
    423 	ACPI_STATUS rv;
    424 
    425 	if (AcpiGetType(handle, &type) == AE_OK) {
    426 		switch (type) {
    427 		case ACPI_TYPE_DEVICE:
    428 		case ACPI_TYPE_PROCESSOR:
    429 		case ACPI_TYPE_THERMAL:
    430 		case ACPI_TYPE_POWER:
    431 			ad = malloc(sizeof(*ad), M_DEVBUF, M_NOWAIT);
    432 			if (ad == NULL)
    433 				return (AE_NO_MEMORY);
    434 			memset(ad, 0, sizeof(*ad));
    435 
    436 			ad->ad_handle = handle;
    437 			ad->ad_level = level;
    438 			ad->ad_scope = as;
    439 			ad->ad_type = type;
    440 
    441 			TAILQ_INSERT_TAIL(&as->as_devnodes, ad, ad_list);
    442 
    443 			rv = AcpiGetObjectInfo(handle, &ad->ad_devinfo);
    444 			if (rv != AE_OK)
    445 				goto out;
    446 
    447 			if ((ad->ad_devinfo.Valid & ACPI_VALID_HID) == 0)
    448 				goto out;
    449 
    450 #ifdef ACPI_DEBUG
    451 			printf("%s: HID %s found in scope %s level %d\n",
    452 			    sc->sc_dev.dv_xname, ad->ad_devinfo.HardwareId,
    453 			    as->as_name, ad->ad_level);
    454 			if (ad->ad_devinfo.Valid & ACPI_VALID_UID)
    455 				printf("       UID %s\n",
    456 				    ad->ad_devinfo.UniqueId);
    457 			if (ad->ad_devinfo.Valid & ACPI_VALID_ADR)
    458 				printf("       ADR 0x%016qx\n",
    459 				    ad->ad_devinfo.Address);
    460 			if (ad->ad_devinfo.Valid & ACPI_VALID_STA)
    461 				printf("       STA 0x%08x\n",
    462 				    ad->ad_devinfo.CurrentStatus);
    463 #endif
    464 		}
    465 	}
    466  out:
    467 	return (AE_OK);
    468 }
    469 
    470 /*
    471  * acpi_print:
    472  *
    473  *	Autoconfiguration print routine.
    474  */
    475 int
    476 acpi_print(void *aux, const char *pnp)
    477 {
    478 	struct acpi_attach_args *aa = aux;
    479 	char *str;
    480 
    481 	if (pnp) {
    482 		printf("%s ", aa->aa_node->ad_devinfo.HardwareId);
    483 		if (acpi_eval_string(aa->aa_node->ad_handle,
    484 		    "_STR", &str) == AE_OK) {
    485 			printf("[%s] ", str);
    486 			AcpiOsFree(str);
    487 		}
    488 		printf("at %s", pnp);
    489 	}
    490 
    491 	return (UNCONF);
    492 }
    493 
    494 /*****************************************************************************
    495  * ACPI fixed-hardware feature handlers
    496  *****************************************************************************/
    497 
    498 UINT32		acpi_fixed_power_button_handler(void *);
    499 UINT32		acpi_fixed_sleep_button_handler(void *);
    500 
    501 /*
    502  * acpi_enable_fixed_events:
    503  *
    504  *	Enable any fixed-hardware feature handlers.
    505  */
    506 void
    507 acpi_enable_fixed_events(struct acpi_softc *sc)
    508 {
    509 	static int beenhere;
    510 	ACPI_STATUS rv;
    511 
    512 	/*
    513 	 * Check for fixed-hardware buttons.
    514 	 */
    515 
    516 	if (AcpiGbl_FADT != NULL && AcpiGbl_FADT->PwrButton == 0) {
    517 		if (beenhere == 0)
    518 			printf("%s: fixed-feature power button present\n",
    519 			    sc->sc_dev.dv_xname);
    520 		rv = AcpiInstallFixedEventHandler(ACPI_EVENT_POWER_BUTTON,
    521 		    acpi_fixed_power_button_handler, sc);
    522 		if (rv != AE_OK)
    523 			printf("%s: unable to install handler for fixed "
    524 			    "power button: %d\n", sc->sc_dev.dv_xname, rv);
    525 	}
    526 
    527 	if (AcpiGbl_FADT != NULL && AcpiGbl_FADT->SleepButton == 0) {
    528 		if (beenhere == 0)
    529 			printf("%s: fixed-feature sleep button present\n",
    530 			    sc->sc_dev.dv_xname);
    531 		rv = AcpiInstallFixedEventHandler(ACPI_EVENT_SLEEP_BUTTON,
    532 		    acpi_fixed_sleep_button_handler, sc);
    533 		if (rv != AE_OK)
    534 			printf("%s: unable to install handler for fixed "
    535 			    "power button: %d\n", sc->sc_dev.dv_xname, rv);
    536 	}
    537 
    538 	beenhere = 1;
    539 }
    540 
    541 /*
    542  * acpi_fixed_power_button_handler:
    543  *
    544  *	Fixed event handler for the power button.
    545  */
    546 UINT32
    547 acpi_fixed_power_button_handler(void *context)
    548 {
    549 	struct acpi_softc *sc = context;
    550 
    551 	/* XXX XXX XXX */
    552 
    553 	printf("%s: fixed power button pressed\n", sc->sc_dev.dv_xname);
    554 
    555 	return (INTERRUPT_HANDLED);
    556 }
    557 
    558 /*
    559  * acpi_fixed_sleep_button_handler:
    560  *
    561  *	Fixed event handler for the sleep button.
    562  */
    563 UINT32
    564 acpi_fixed_sleep_button_handler(void *context)
    565 {
    566 	struct acpi_softc *sc = context;
    567 
    568 	/* XXX XXX XXX */
    569 
    570 	printf("%s: fixed sleep button pressed\n", sc->sc_dev.dv_xname);
    571 
    572 	return (INTERRUPT_HANDLED);
    573 }
    574 
    575 /*****************************************************************************
    576  * ACPI utility routines.
    577  *****************************************************************************/
    578 
    579 /*
    580  * acpi_eval_integer:
    581  *
    582  *	Evaluate an integer object.
    583  */
    584 ACPI_STATUS
    585 acpi_eval_integer(ACPI_HANDLE handle, char *path, int *valp)
    586 {
    587 	ACPI_STATUS rv;
    588 	ACPI_BUFFER buf;
    589 	ACPI_OBJECT param;
    590 
    591 	if (handle == NULL)
    592 		handle = ACPI_ROOT_OBJECT;
    593 
    594 	buf.Pointer = &param;
    595 	buf.Length = sizeof(param);
    596 
    597 	rv = AcpiEvaluateObject(handle, path, NULL, &buf);
    598 	if (rv == AE_OK) {
    599 		if (param.Type == ACPI_TYPE_INTEGER)
    600 			*valp = param.Integer.Value;
    601 		else
    602 			rv = AE_TYPE;
    603 	}
    604 
    605 	return (rv);
    606 }
    607 
    608 /*
    609  * acpi_eval_string:
    610  *
    611  *	Evaluage a (Unicode) string object.
    612  */
    613 ACPI_STATUS
    614 acpi_eval_string(ACPI_HANDLE handle, char *path, char **stringp)
    615 {
    616 	ACPI_STATUS rv;
    617 	ACPI_BUFFER buf;
    618 	ACPI_OBJECT param;
    619 
    620 	if (handle == NULL)
    621 		handle = ACPI_ROOT_OBJECT;
    622 
    623 	buf.Pointer = NULL;
    624 	buf.Length = 0;
    625 
    626 	rv = AcpiEvaluateObject(handle, path, NULL, &buf);
    627 	if (rv != AE_BUFFER_OVERFLOW)
    628 		return (rv);
    629 
    630 	buf.Pointer = AcpiOsAllocate(buf.Length);
    631 	if (buf.Pointer == NULL)
    632 		return (AE_NO_MEMORY);
    633 
    634 	rv = AcpiEvaluateObject(handle, path, NULL, &buf);
    635 	if (rv == AE_OK) {
    636 		if (param.Type == ACPI_TYPE_STRING) {
    637 			*stringp = buf.Pointer;
    638 			return (AE_OK);
    639 		}
    640 		rv = AE_TYPE;
    641 	}
    642 
    643 	AcpiOsFree(buf.Pointer);
    644 	return (rv);
    645 }
    646 
    647 /*
    648  * acpi_get:
    649  *
    650  *	Fetch data info the specified (empty) ACPI buffer.
    651  */
    652 ACPI_STATUS
    653 acpi_get(ACPI_HANDLE handle, ACPI_BUFFER *buf,
    654     ACPI_STATUS (*getit)(ACPI_HANDLE, ACPI_BUFFER *))
    655 {
    656 	ACPI_STATUS rv;
    657 
    658 	buf->Pointer = NULL;
    659 	buf->Length = 0;
    660 
    661 	rv = (*getit)(handle, buf);
    662 	if (rv != AE_BUFFER_OVERFLOW)
    663 		return (rv);
    664 
    665 	buf->Pointer = AcpiOsCallocate(buf->Length);
    666 	if (buf->Pointer == NULL)
    667 		return (AE_NO_MEMORY);
    668 
    669 	return ((*getit)(handle, buf));
    670 }
    671