xref: /netbsd-src/sys/dev/acpi/wmi/wmi_acpi.c (revision 796c32c94f6e154afc9de0f63da35c91bb739b45)
1 /*	$NetBSD: wmi_acpi.c,v 1.15 2017/06/01 02:45:09 chs Exp $	*/
2 
3 /*-
4  * Copyright (c) 2009, 2010 Jukka Ruohonen <jruohonen@iki.fi>
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  *
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  */
29 #include <sys/cdefs.h>
30 __KERNEL_RCSID(0, "$NetBSD: wmi_acpi.c,v 1.15 2017/06/01 02:45:09 chs Exp $");
31 
32 #include <sys/param.h>
33 #include <sys/device.h>
34 #include <sys/endian.h>
35 #include <sys/kmem.h>
36 #include <sys/systm.h>
37 #include <sys/module.h>
38 
39 #include <dev/acpi/acpireg.h>
40 #include <dev/acpi/acpivar.h>
41 #include <dev/acpi/acpi_ecvar.h>
42 #include <dev/acpi/wmi/wmi_acpivar.h>
43 
44 #define _COMPONENT          ACPI_RESOURCE_COMPONENT
45 ACPI_MODULE_NAME            ("wmi_acpi")
46 
47 /*
48  * This implements something called "Microsoft Windows Management
49  * Instrumentation" (WMI). This subset of ACPI is desribed in:
50  *
51  * http://www.microsoft.com/whdc/system/pnppwr/wmi/wmi-acpi.mspx
52  *
53  * (Obtained on Thu Feb 12 18:21:44 EET 2009.)
54  */
55 
56 static int		acpi_wmi_match(device_t, cfdata_t, void *);
57 static void		acpi_wmi_attach(device_t, device_t, void *);
58 static int		acpi_wmi_detach(device_t, int);
59 static int		acpi_wmi_rescan(device_t, const char *, const int *);
60 static void		acpi_wmi_childdet(device_t, device_t);
61 static int		acpi_wmi_print(void *, const char *);
62 static bool		acpi_wmi_init(struct acpi_wmi_softc *);
63 static void		acpi_wmi_init_ec(struct acpi_wmi_softc *);
64 static void		acpi_wmi_add(struct acpi_wmi_softc *, ACPI_OBJECT *);
65 static void		acpi_wmi_del(struct acpi_wmi_softc *);
66 static void		acpi_wmi_dump(struct acpi_wmi_softc *);
67 static ACPI_STATUS	acpi_wmi_guid_get(struct acpi_wmi_softc *,
68 				const char *, struct wmi_t **);
69 static void		acpi_wmi_event_add(struct acpi_wmi_softc *);
70 static void		acpi_wmi_event_del(struct acpi_wmi_softc *);
71 static void		acpi_wmi_event_handler(ACPI_HANDLE, uint32_t, void *);
72 static ACPI_STATUS	acpi_wmi_ec_handler(uint32_t, ACPI_PHYSICAL_ADDRESS,
73 				uint32_t, ACPI_INTEGER *, void *, void *);
74 static bool		acpi_wmi_suspend(device_t, const pmf_qual_t *);
75 static bool		acpi_wmi_resume(device_t, const pmf_qual_t *);
76 static ACPI_STATUS	acpi_wmi_enable_event(ACPI_HANDLE, uint8_t, bool);
77 static ACPI_STATUS	acpi_wmi_enable_collection(ACPI_HANDLE, const char *, bool);
78 static bool		acpi_wmi_input(struct wmi_t *, uint8_t, uint8_t);
79 
80 const char * const acpi_wmi_ids[] = {
81 	"PNP0C14",
82 	"pnp0c14",
83 	NULL
84 };
85 
86 CFATTACH_DECL2_NEW(acpiwmi, sizeof(struct acpi_wmi_softc),
87     acpi_wmi_match, acpi_wmi_attach, acpi_wmi_detach, NULL,
88     acpi_wmi_rescan, acpi_wmi_childdet);
89 
90 static int
91 acpi_wmi_match(device_t parent, cfdata_t match, void *aux)
92 {
93 	struct acpi_attach_args *aa = aux;
94 
95 	if (aa->aa_node->ad_type != ACPI_TYPE_DEVICE)
96 		return 0;
97 
98 	return acpi_match_hid(aa->aa_node->ad_devinfo, acpi_wmi_ids);
99 }
100 
101 static void
102 acpi_wmi_attach(device_t parent, device_t self, void *aux)
103 {
104 	struct acpi_wmi_softc *sc = device_private(self);
105 	struct acpi_attach_args *aa = aux;
106 
107 	sc->sc_dev = self;
108 	sc->sc_node = aa->aa_node;
109 
110 	sc->sc_child = NULL;
111 	sc->sc_ecdev = NULL;
112 	sc->sc_handler = NULL;
113 
114 	aprint_naive("\n");
115 	aprint_normal(": ACPI WMI Interface\n");
116 
117 	if (acpi_wmi_init(sc) != true)
118 		return;
119 
120 	acpi_wmi_dump(sc);
121 	acpi_wmi_init_ec(sc);
122 	acpi_wmi_event_add(sc);
123 	acpi_wmi_rescan(self, NULL, NULL);
124 
125 	(void)pmf_device_register(self, acpi_wmi_suspend, acpi_wmi_resume);
126 }
127 
128 static int
129 acpi_wmi_detach(device_t self, int flags)
130 {
131 	struct acpi_wmi_softc *sc = device_private(self);
132 
133 	acpi_wmi_event_del(sc);
134 
135 	if (sc->sc_ecdev != NULL) {
136 
137 		(void)AcpiRemoveAddressSpaceHandler(sc->sc_node->ad_handle,
138 		    ACPI_ADR_SPACE_EC, acpi_wmi_ec_handler);
139 	}
140 
141 	if (sc->sc_child != NULL)
142 		(void)config_detach(sc->sc_child, flags);
143 
144 	acpi_wmi_del(sc);
145 	pmf_device_deregister(self);
146 
147 	return 0;
148 }
149 
150 static int
151 acpi_wmi_rescan(device_t self, const char *ifattr, const int *locators)
152 {
153 	struct acpi_wmi_softc *sc = device_private(self);
154 
155 	if (ifattr_match(ifattr, "acpiwmibus") && sc->sc_child == NULL)
156 		sc->sc_child = config_found_ia(self, "acpiwmibus",
157 		    NULL, acpi_wmi_print);
158 
159 	return 0;
160 }
161 
162 static void
163 acpi_wmi_childdet(device_t self, device_t child)
164 {
165 	struct acpi_wmi_softc *sc = device_private(self);
166 
167 	if (sc->sc_child == child)
168 		sc->sc_child = NULL;
169 }
170 
171 static int
172 acpi_wmi_print(void *aux, const char *pnp)
173 {
174 
175 	if (pnp != NULL)
176 		aprint_normal("acpiwmibus at %s", pnp);
177 
178 	return UNCONF;
179 }
180 
181 static bool
182 acpi_wmi_init(struct acpi_wmi_softc *sc)
183 {
184 	ACPI_OBJECT *obj;
185 	ACPI_BUFFER buf;
186 	ACPI_STATUS rv;
187 	uint32_t len;
188 
189 	rv = acpi_eval_struct(sc->sc_node->ad_handle, "_WDG", &buf);
190 
191 	if (ACPI_FAILURE(rv))
192 		goto fail;
193 
194 	obj = buf.Pointer;
195 
196 	if (obj->Type != ACPI_TYPE_BUFFER) {
197 		rv = AE_TYPE;
198 		goto fail;
199 	}
200 
201 	len = obj->Buffer.Length;
202 
203 	if (len != obj->Package.Count) {
204 		rv = AE_BAD_VALUE;
205 		goto fail;
206 	}
207 
208 	CTASSERT(sizeof(struct guid_t) == 20);
209 
210 	if (len < sizeof(struct guid_t) ||
211 	    len % sizeof(struct guid_t) != 0) {
212 		rv = AE_BAD_DATA;
213 		goto fail;
214 	}
215 
216 	acpi_wmi_add(sc, obj);
217 	return true;
218 
219 fail:
220 	aprint_error_dev(sc->sc_dev, "failed to evaluate _WDG: %s\n",
221 	    AcpiFormatException(rv));
222 
223 	if (buf.Pointer != NULL)
224 		ACPI_FREE(buf.Pointer);
225 
226 	return false;
227 }
228 
229 static void
230 acpi_wmi_add(struct acpi_wmi_softc *sc, ACPI_OBJECT *obj)
231 {
232 	struct wmi_t *wmi;
233 	size_t i, n, offset, siz;
234 
235 	siz = sizeof(struct guid_t);
236 	n = obj->Buffer.Length / siz;
237 
238 	SIMPLEQ_INIT(&sc->wmi_head);
239 
240 	for (i = offset = 0; i < n; ++i) {
241 
242 		wmi = kmem_zalloc(sizeof(*wmi), KM_SLEEP);
243 		(void)memcpy(&wmi->guid, obj->Buffer.Pointer + offset, siz);
244 
245 		wmi->eevent = false;
246 		offset = offset + siz;
247 
248 		SIMPLEQ_INSERT_TAIL(&sc->wmi_head, wmi, wmi_link);
249 	}
250 
251 	ACPI_FREE(obj);
252 }
253 
254 static void
255 acpi_wmi_del(struct acpi_wmi_softc *sc)
256 {
257 	struct wmi_t *wmi;
258 
259 	while (SIMPLEQ_FIRST(&sc->wmi_head) != NULL) {
260 		wmi = SIMPLEQ_FIRST(&sc->wmi_head);
261 		SIMPLEQ_REMOVE_HEAD(&sc->wmi_head, wmi_link);
262 		kmem_free(wmi, sizeof(*wmi));
263 	}
264 }
265 
266 static void
267 acpi_wmi_dump(struct acpi_wmi_softc *sc)
268 {
269 	struct wmi_t *wmi;
270 
271 	KASSERT(SIMPLEQ_EMPTY(&sc->wmi_head) == 0);
272 
273 	SIMPLEQ_FOREACH(wmi, &sc->wmi_head, wmi_link) {
274 
275 		aprint_debug_dev(sc->sc_dev, "{%08X-%04X-%04X-",
276 		    wmi->guid.data1, wmi->guid.data2, wmi->guid.data3);
277 
278 		aprint_debug("%02X%02X-%02X%02X%02X%02X%02X%02X} ",
279 		    wmi->guid.data4[0], wmi->guid.data4[1],
280 		    wmi->guid.data4[2], wmi->guid.data4[3],
281 		    wmi->guid.data4[4], wmi->guid.data4[5],
282 		    wmi->guid.data4[6], wmi->guid.data4[7]);
283 
284 		aprint_debug("oid %04X count %02X flags %02X\n",
285 		    UGET16(wmi->guid.oid), wmi->guid.count, wmi->guid.flags);
286 	}
287 }
288 
289 static void
290 acpi_wmi_init_ec(struct acpi_wmi_softc *sc)
291 {
292 	ACPI_STATUS rv;
293 	deviter_t i;
294 	device_t d;
295 
296 	d = deviter_first(&i, DEVITER_F_ROOT_FIRST);
297 
298 	for (; d != NULL; d = deviter_next(&i)) {
299 
300 		if (device_is_a(d, "acpiec") != false ||
301 		    device_is_a(d, "acpiecdt") != false) {
302 			sc->sc_ecdev = d;
303 			break;
304 		}
305 	}
306 
307 	deviter_release(&i);
308 
309 	if (sc->sc_ecdev == NULL)
310 		return;
311 
312 	rv = AcpiInstallAddressSpaceHandler(sc->sc_node->ad_handle,
313 	    ACPI_ADR_SPACE_EC, acpi_wmi_ec_handler, NULL, sc);
314 
315 	if (ACPI_FAILURE(rv))
316 		sc->sc_ecdev = NULL;
317 }
318 
319 static ACPI_STATUS
320 acpi_wmi_guid_get(struct acpi_wmi_softc *sc,
321     const char *src, struct wmi_t **out)
322 {
323 	struct wmi_t *wmi;
324 	struct guid_t *guid;
325 	char bin[16];
326 	char hex[2];
327 	const char *ptr;
328 	uint8_t i;
329 
330 	if (sc == NULL || src == NULL || strlen(src) != 36)
331 		return AE_BAD_PARAMETER;
332 
333 	for (ptr = src, i = 0; i < 16; i++) {
334 
335 		if (*ptr == '-')
336 			ptr++;
337 
338 		(void)memcpy(hex, ptr, 2);
339 
340 		if (HEXCHAR(hex[0]) == 0 || HEXCHAR(hex[1]) == 0)
341 			return AE_BAD_HEX_CONSTANT;
342 
343 		bin[i] = strtoul(hex, NULL, 16) & 0xFF;
344 
345 		ptr++;
346 		ptr++;
347 	}
348 
349 	guid = (struct guid_t *)bin;
350 	guid->data1 = be32toh(guid->data1);
351 	guid->data2 = be16toh(guid->data2);
352 	guid->data3 = be16toh(guid->data3);
353 
354 	SIMPLEQ_FOREACH(wmi, &sc->wmi_head, wmi_link) {
355 
356 		if (GUIDCMP(guid, &wmi->guid) != 0) {
357 
358 			if (out != NULL)
359 				*out = wmi;
360 
361 			return AE_OK;
362 		}
363 	}
364 
365 	return AE_NOT_FOUND;
366 }
367 
368 /*
369  * Checks if a GUID is present. Child devices
370  * can use this in their autoconf(9) routines.
371  */
372 int
373 acpi_wmi_guid_match(device_t self, const char *guid)
374 {
375 	struct acpi_wmi_softc *sc = device_private(self);
376 	ACPI_STATUS rv;
377 
378 	rv = acpi_wmi_guid_get(sc, guid, NULL);
379 
380 	if (ACPI_SUCCESS(rv))
381 		return 1;
382 
383 	return 0;
384 }
385 
386 /*
387  * Adds internal event handler.
388  */
389 static void
390 acpi_wmi_event_add(struct acpi_wmi_softc *sc)
391 {
392 	struct wmi_t *wmi;
393 	ACPI_STATUS rv;
394 
395 	if (acpi_register_notify(sc->sc_node, acpi_wmi_event_handler) != true)
396 		return;
397 
398 	/*
399 	 * Enable possible events, expensive or otherwise.
400 	 */
401 	SIMPLEQ_FOREACH(wmi, &sc->wmi_head, wmi_link) {
402 
403 		if ((wmi->guid.flags & ACPI_WMI_FLAG_EVENT) != 0) {
404 
405 			rv = acpi_wmi_enable_event(sc->sc_node->ad_handle,
406 			    wmi->guid.nid, true);
407 
408 			if (ACPI_SUCCESS(rv)) {
409 				wmi->eevent = true;
410 				continue;
411 			}
412 
413 			aprint_debug_dev(sc->sc_dev, "failed to enable "
414 			    "expensive WExx: %s\n", AcpiFormatException(rv));
415 		}
416 	}
417 }
418 
419 /*
420  * Removes the internal event handler.
421  */
422 static void
423 acpi_wmi_event_del(struct acpi_wmi_softc *sc)
424 {
425 	struct wmi_t *wmi;
426 	ACPI_STATUS rv;
427 
428 	acpi_deregister_notify(sc->sc_node);
429 
430 	SIMPLEQ_FOREACH(wmi, &sc->wmi_head, wmi_link) {
431 
432 		if (wmi->eevent != true)
433 			continue;
434 
435 		KASSERT((wmi->guid.flags & ACPI_WMI_FLAG_EVENT) != 0);
436 
437 		rv = acpi_wmi_enable_event(sc->sc_node->ad_handle,
438 		    wmi->guid.nid, false);
439 
440 		if (ACPI_SUCCESS(rv)) {
441 			wmi->eevent = false;
442 			continue;
443 		}
444 
445 		aprint_debug_dev(sc->sc_dev, "failed to disable "
446 		    "expensive WExx: %s\n", AcpiFormatException(rv));
447 	}
448 }
449 
450 /*
451  * Returns extra information possibly associated with an event.
452  */
453 ACPI_STATUS
454 acpi_wmi_event_get(device_t self, uint32_t event, ACPI_BUFFER *obuf)
455 {
456 	struct acpi_wmi_softc *sc = device_private(self);
457 	struct wmi_t *wmi;
458 	ACPI_OBJECT_LIST arg;
459 	ACPI_OBJECT obj;
460 	ACPI_HANDLE hdl;
461 
462 	if (sc == NULL || obuf == NULL)
463 		return AE_BAD_PARAMETER;
464 
465 	if (sc->sc_handler == NULL)
466 		return AE_ABORT_METHOD;
467 
468 	hdl = sc->sc_node->ad_handle;
469 
470 	obj.Type = ACPI_TYPE_INTEGER;
471 	obj.Integer.Value = event;
472 
473 	arg.Count = 0x01;
474 	arg.Pointer = &obj;
475 
476 	obuf->Pointer = NULL;
477 	obuf->Length = ACPI_ALLOCATE_LOCAL_BUFFER;
478 
479 	SIMPLEQ_FOREACH(wmi, &sc->wmi_head, wmi_link) {
480 
481 		if ((wmi->guid.flags & ACPI_WMI_FLAG_EVENT) == 0)
482 			continue;
483 
484 		if (wmi->guid.nid != event)
485 			continue;
486 
487 		return AcpiEvaluateObject(hdl, "_WED", &arg, obuf);
488 	}
489 
490 	return AE_NOT_FOUND;
491 }
492 
493 /*
494  * Forwards events to the external handler through the internal one.
495  */
496 static void
497 acpi_wmi_event_handler(ACPI_HANDLE hdl, uint32_t evt, void *aux)
498 {
499 	struct acpi_wmi_softc *sc;
500 	device_t self = aux;
501 
502 	sc = device_private(self);
503 
504 	if (sc->sc_child == NULL)
505 		return;
506 
507 	if (sc->sc_handler == NULL)
508 		return;
509 
510 	(*sc->sc_handler)(NULL, evt, sc->sc_child);
511 }
512 
513 ACPI_STATUS
514 acpi_wmi_event_register(device_t self, ACPI_NOTIFY_HANDLER handler)
515 {
516 	struct acpi_wmi_softc *sc = device_private(self);
517 
518 	if (sc == NULL)
519 		return AE_BAD_PARAMETER;
520 
521 	if (handler != NULL && sc->sc_handler != NULL)
522 		return AE_ALREADY_EXISTS;
523 
524 	sc->sc_handler = handler;
525 
526 	return AE_OK;
527 }
528 
529 ACPI_STATUS
530 acpi_wmi_event_deregister(device_t self)
531 {
532 	return acpi_wmi_event_register(self, NULL);
533 }
534 
535 /*
536  * Handler for EC regions, which may be embedded in WMI.
537  */
538 static ACPI_STATUS
539 acpi_wmi_ec_handler(uint32_t func, ACPI_PHYSICAL_ADDRESS addr,
540     uint32_t width, ACPI_INTEGER *val, void *setup, void *aux)
541 {
542 	struct acpi_wmi_softc *sc = aux;
543 
544 	if (aux == NULL || val == NULL)
545 		return AE_BAD_PARAMETER;
546 
547 	if (addr > 0xFF || width % 8 != 0)
548 		return AE_BAD_ADDRESS;
549 
550 	switch (func) {
551 
552 	case ACPI_READ:
553 		(void)acpiec_bus_read(sc->sc_ecdev, addr, val, width);
554 		break;
555 
556 	case ACPI_WRITE:
557 		(void)acpiec_bus_write(sc->sc_ecdev, addr, *val, width);
558 		break;
559 
560 	default:
561 		return AE_BAD_PARAMETER;
562 	}
563 
564 	return AE_OK;
565 }
566 
567 /*
568  * As there is no prior knowledge about the expensive
569  * events that cause "significant overhead", try to
570  * disable (enable) these before suspending (resuming).
571  */
572 static bool
573 acpi_wmi_suspend(device_t self, const pmf_qual_t *qual)
574 {
575 	struct acpi_wmi_softc *sc = device_private(self);
576 
577 	acpi_wmi_event_del(sc);
578 
579 	return true;
580 }
581 
582 static bool
583 acpi_wmi_resume(device_t self, const pmf_qual_t *qual)
584 {
585 	struct acpi_wmi_softc *sc = device_private(self);
586 
587 	acpi_wmi_event_add(sc);
588 
589 	return true;
590 }
591 
592 static ACPI_STATUS
593 acpi_wmi_enable_event(ACPI_HANDLE hdl, uint8_t nid, bool flag)
594 {
595 	char path[5];
596 
597 	snprintf(path, sizeof(path), "WE%02X", nid);
598 
599 	return acpi_eval_set_integer(hdl, path, (flag != false) ? 0x01 : 0x00);
600 }
601 
602 static ACPI_STATUS
603 acpi_wmi_enable_collection(ACPI_HANDLE hdl, const char *oid, bool flag)
604 {
605 	char path[5];
606 
607 	strlcpy(path, "WC", sizeof(path));
608 	strlcat(path, oid, sizeof(path));
609 
610 	return acpi_eval_set_integer(hdl, path, (flag != false) ? 0x01 : 0x00);
611 }
612 
613 static bool
614 acpi_wmi_input(struct wmi_t *wmi, uint8_t flag, uint8_t idx)
615 {
616 
617 	if ((wmi->guid.flags & flag) == 0)
618 		return false;
619 
620 	if (wmi->guid.count == 0x00)
621 		return false;
622 
623 	if (wmi->guid.count < idx)
624 		return false;
625 
626 	return true;
627 }
628 
629 /*
630  * Makes a WMI data block query (WQxx). The corresponding control
631  * method for data collection will be invoked if it is available.
632  */
633 ACPI_STATUS
634 acpi_wmi_data_query(device_t self, const char *guid,
635     uint8_t idx, ACPI_BUFFER *obuf)
636 {
637 	struct acpi_wmi_softc *sc = device_private(self);
638 	struct wmi_t *wmi;
639 	char path[5] = "WQ";
640 	ACPI_OBJECT_LIST arg;
641 	ACPI_STATUS rv, rvxx;
642 	ACPI_OBJECT obj;
643 
644 	rvxx = AE_SUPPORT;
645 
646 	if (obuf == NULL)
647 		return AE_BAD_PARAMETER;
648 
649 	rv = acpi_wmi_guid_get(sc, guid, &wmi);
650 
651 	if (ACPI_FAILURE(rv))
652 		return rv;
653 
654 	if (acpi_wmi_input(wmi, ACPI_WMI_FLAG_DATA, idx) != true)
655 		return AE_BAD_DATA;
656 
657 	(void)strlcat(path, wmi->guid.oid, sizeof(path));
658 
659 	obj.Type = ACPI_TYPE_INTEGER;
660 	obj.Integer.Value = idx;
661 
662 	arg.Count = 0x01;
663 	arg.Pointer = &obj;
664 
665 	obuf->Pointer = NULL;
666 	obuf->Length = ACPI_ALLOCATE_LOCAL_BUFFER;
667 
668 	/*
669 	 * If the expensive flag is set, we should enable
670 	 * data collection before evaluating the WQxx buffer.
671 	 */
672 	if ((wmi->guid.flags & ACPI_WMI_FLAG_EXPENSIVE) != 0) {
673 
674 		rvxx = acpi_wmi_enable_collection(sc->sc_node->ad_handle,
675 		    wmi->guid.oid, true);
676 	}
677 
678 	rv = AcpiEvaluateObject(sc->sc_node->ad_handle, path, &arg, obuf);
679 
680 	/* No longer needed. */
681 	if (ACPI_SUCCESS(rvxx)) {
682 
683 		(void)acpi_wmi_enable_collection(sc->sc_node->ad_handle,
684 		    wmi->guid.oid, false);
685 	}
686 
687 #ifdef DIAGNOSTIC
688 	/*
689 	 * XXX: It appears that quite a few laptops have WQxx
690 	 * methods that are declared as expensive, but lack the
691 	 * corresponding WCxx control method.
692 	 *
693 	 * -- Acer Aspire One is one example <jruohonen@iki.fi>.
694 	 */
695 	if (ACPI_FAILURE(rvxx) && rvxx != AE_SUPPORT)
696 		aprint_error_dev(sc->sc_dev, "failed to evaluate WCxx "
697 		    "for %s: %s\n", path, AcpiFormatException(rvxx));
698 #endif
699 	return rv;
700 }
701 
702 /*
703  * Writes to a data block (WSxx).
704  */
705 ACPI_STATUS
706 acpi_wmi_data_write(device_t self, const char *guid,
707     uint8_t idx, ACPI_BUFFER *ibuf)
708 {
709 	struct acpi_wmi_softc *sc = device_private(self);
710 	struct wmi_t *wmi;
711 	ACPI_OBJECT_LIST arg;
712 	ACPI_OBJECT obj[2];
713 	char path[5] = "WS";
714 	ACPI_STATUS rv;
715 
716 	if (ibuf == NULL)
717 		return AE_BAD_PARAMETER;
718 
719 	rv = acpi_wmi_guid_get(sc, guid, &wmi);
720 
721 	if (ACPI_FAILURE(rv))
722 		return rv;
723 
724 	if (acpi_wmi_input(wmi, ACPI_WMI_FLAG_DATA, idx) != true)
725 		return AE_BAD_DATA;
726 
727 	(void)strlcat(path, wmi->guid.oid, sizeof(path));
728 
729 	obj[0].Integer.Value = idx;
730 	obj[0].Type = ACPI_TYPE_INTEGER;
731 
732 	obj[1].Buffer.Length = ibuf->Length;
733 	obj[1].Buffer.Pointer = ibuf->Pointer;
734 
735 	obj[1].Type = ((wmi->guid.flags & ACPI_WMI_FLAG_STRING) != 0) ?
736 	    ACPI_TYPE_STRING : ACPI_TYPE_BUFFER;
737 
738 	arg.Count = 0x02;
739 	arg.Pointer = obj;
740 
741 	return AcpiEvaluateObject(sc->sc_node->ad_handle, path, &arg, NULL);
742 }
743 
744 /*
745  * Executes a method (WMxx).
746  */
747 ACPI_STATUS
748 acpi_wmi_method(device_t self, const char *guid, uint8_t idx,
749     uint32_t mid, ACPI_BUFFER *ibuf, ACPI_BUFFER *obuf)
750 {
751 	struct acpi_wmi_softc *sc = device_private(self);
752 	struct wmi_t *wmi;
753 	ACPI_OBJECT_LIST arg;
754 	ACPI_OBJECT obj[3];
755 	char path[5] = "WM";
756 	ACPI_STATUS rv;
757 
758 	if (ibuf == NULL || obuf == NULL)
759 		return AE_BAD_PARAMETER;
760 
761 	rv = acpi_wmi_guid_get(sc, guid, &wmi);
762 
763 	if (ACPI_FAILURE(rv))
764 		return rv;
765 
766 	if (acpi_wmi_input(wmi, ACPI_WMI_FLAG_METHOD, idx) != true)
767 		return AE_BAD_DATA;
768 
769 	(void)strlcat(path, wmi->guid.oid, sizeof(path));
770 
771 	obj[0].Integer.Value = idx;
772 	obj[1].Integer.Value = mid;
773 	obj[0].Type = obj[1].Type = ACPI_TYPE_INTEGER;
774 
775 	obj[2].Buffer.Length = ibuf->Length;
776 	obj[2].Buffer.Pointer = ibuf->Pointer;
777 
778 	obj[2].Type = ((wmi->guid.flags & ACPI_WMI_FLAG_STRING) != 0) ?
779 	    ACPI_TYPE_STRING : ACPI_TYPE_BUFFER;
780 
781 	arg.Count = 0x03;
782 	arg.Pointer = obj;
783 
784 	obuf->Pointer = NULL;
785 	obuf->Length = ACPI_ALLOCATE_LOCAL_BUFFER;
786 
787 	return AcpiEvaluateObject(sc->sc_node->ad_handle, path, &arg, obuf);
788 }
789 
790 MODULE(MODULE_CLASS_DRIVER, acpiwmi, NULL);
791 
792 #ifdef _MODULE
793 #include "ioconf.c"
794 #endif
795 
796 static int
797 acpiwmi_modcmd(modcmd_t cmd, void *aux)
798 {
799 	int rv = 0;
800 
801 	switch (cmd) {
802 
803 	case MODULE_CMD_INIT:
804 
805 #ifdef _MODULE
806 		rv = config_init_component(cfdriver_ioconf_acpiwmi,
807 		    cfattach_ioconf_acpiwmi, cfdata_ioconf_acpiwmi);
808 #endif
809 		break;
810 
811 	case MODULE_CMD_FINI:
812 
813 #ifdef _MODULE
814 		rv = config_fini_component(cfdriver_ioconf_acpiwmi,
815 		    cfattach_ioconf_acpiwmi, cfdata_ioconf_acpiwmi);
816 #endif
817 		break;
818 
819 	default:
820 		rv = ENOTTY;
821 	}
822 
823 	return rv;
824 }
825