xref: /netbsd-src/sys/dev/acpi/acpi_pci_link.c (revision 1ad9454efb13a65cd7535ccf867508cb14d9d30e)
1 /*	$NetBSD: acpi_pci_link.c,v 1.5 2006/09/23 17:05:33 fvdl Exp $	*/
2 
3 /*-
4  * Copyright (c) 2002 Mitsuru IWASAKI <iwasaki@jp.freebsd.org>
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  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  */
28 
29 #include <sys/cdefs.h>
30 __KERNEL_RCSID(0, "$NetBSD: acpi_pci_link.c,v 1.5 2006/09/23 17:05:33 fvdl Exp $");
31 
32 #include "opt_acpi.h"
33 #include <sys/param.h>
34 #include <sys/kernel.h>
35 #include <sys/malloc.h>
36 #include <sys/queue.h>
37 #include <sys/reboot.h>
38 
39 #include <dev/acpi/acpica.h>
40 #include <dev/acpi/acpireg.h>
41 #include <dev/acpi/acpivar.h>
42 
43 #include <dev/pci/pcireg.h>
44 #include <dev/pci/pcivar.h>
45 
46 #define NUM_ISA_INTERRUPTS	16
47 #define NUM_ACPI_INTERRUPTS	256
48 
49 #define PCI_INVALID_IRQ	255
50 #define PCI_INTERRUPT_VALID(x) ((x) != PCI_INVALID_IRQ && (x) != 0)
51 
52 #define ACPI_SERIAL_BEGIN(x)
53 #define ACPI_SERIAL_END(x)
54 
55 /*
56  * An ACPI PCI link device may contain multiple links.  Each link has its
57  * own ACPI resource.  _PRT entries specify which link is being used via
58  * the Source Index.
59  *
60  * XXX: A note about Source Indices and DPFs:  Currently we assume that
61  * the DPF start and end tags are not counted towards the index that
62  * Source Index corresponds to.  Also, we assume that when DPFs are in use
63  * they various sets overlap in terms of Indices.  Here's an example
64  * resource list indicating these assumptions:
65  *
66  * Resource		Index
67  * --------		-----
68  * I/O Port		0
69  * Start DPF		-
70  * IRQ			1
71  * MemIO		2
72  * Start DPF		-
73  * IRQ			1
74  * MemIO		2
75  * End DPF		-
76  * DMA Channel		3
77  *
78  * The XXX is because I'm not sure if this is a valid assumption to make.
79  */
80 
81 /* States during DPF processing. */
82 #define	DPF_OUTSIDE	0
83 #define	DPF_FIRST	1
84 #define	DPF_IGNORE	2
85 
86 struct link;
87 
88 struct acpi_pci_link_softc {
89 	int	pl_num_links;
90 	int	pl_crs_bad;
91 	struct link *pl_links;
92 	char pl_name[32];
93 	ACPI_HANDLE pl_handle;
94 	void *pl_powerhook;
95 	TAILQ_ENTRY(acpi_pci_link_softc) pl_list;
96 };
97 
98 static TAILQ_HEAD(, acpi_pci_link_softc) acpi_pci_linkdevs =
99     TAILQ_HEAD_INITIALIZER(acpi_pci_linkdevs);
100 
101 
102 struct link {
103 	struct acpi_pci_link_softc *l_sc;
104 	uint8_t	l_bios_irq;
105 	uint8_t	l_irq;
106 	uint8_t l_trig;
107 	uint8_t l_pol;
108 	uint8_t	l_initial_irq;
109 	int	l_res_index;
110 	int	l_num_irqs;
111 	int	*l_irqs;
112 	int	l_references;
113 	int	l_routed:1;
114 	int	l_isa_irq:1;
115 	ACPI_RESOURCE l_prs_template;
116 };
117 
118 struct link_count_request {
119 	int	in_dpf;
120 	int	count;
121 };
122 
123 struct link_res_request {
124 	struct acpi_pci_link_softc *sc;
125 	int	in_dpf;
126 	int	res_index;
127 	int	link_index;
128 };
129 
130 MALLOC_DEFINE(M_PCI_LINK, "pci_link", "ACPI PCI Link structures");
131 
132 static int pci_link_interrupt_weights[NUM_ACPI_INTERRUPTS];
133 static int pci_link_bios_isa_irqs;
134 
135 static ACPI_STATUS acpi_count_irq_resources(ACPI_RESOURCE *, void *);
136 static ACPI_STATUS link_add_crs(ACPI_RESOURCE *, void *);
137 static ACPI_STATUS link_add_prs(ACPI_RESOURCE *, void *);
138 static int link_valid_irq(struct link *, int);
139 static void acpi_pci_link_dump(struct acpi_pci_link_softc *);
140 static int acpi_pci_link_attach(struct acpi_pci_link_softc *);
141 static uint8_t acpi_pci_link_search_irq(struct acpi_pci_link_softc *, int, int,
142 					int);
143 static void acpi_pci_link_resume(int, void *);
144 static struct link *acpi_pci_link_lookup(struct acpi_pci_link_softc *, int);
145 static ACPI_STATUS acpi_pci_link_srs(struct acpi_pci_link_softc *,
146 				     ACPI_BUFFER *);
147 static ACPI_STATUS acpi_AppendBufferResource(ACPI_BUFFER *, ACPI_RESOURCE *);
148 
149 static ACPI_STATUS
150 acpi_count_irq_resources(ACPI_RESOURCE *res, void *context)
151 {
152 	struct link_count_request *req;
153 
154 	req = (struct link_count_request *)context;
155 	switch (res->Type) {
156 	case ACPI_RESOURCE_TYPE_START_DEPENDENT:
157 		switch (req->in_dpf) {
158 		case DPF_OUTSIDE:
159 			/* We've started the first DPF. */
160 			req->in_dpf = DPF_FIRST;
161 			break;
162 		case DPF_FIRST:
163 			/* We've started the second DPF. */
164 			req->in_dpf = DPF_IGNORE;
165 			break;
166 		}
167 		break;
168 	case ACPI_RESOURCE_TYPE_END_DEPENDENT:
169 		/* We are finished with DPF parsing. */
170 		KASSERT(req->in_dpf != DPF_OUTSIDE);
171 		req->in_dpf = DPF_OUTSIDE;
172 		break;
173 	case ACPI_RESOURCE_TYPE_IRQ:
174 	case ACPI_RESOURCE_TYPE_EXTENDED_IRQ:
175 		/*
176 		 * Don't count resources if we are in a DPF set that we are
177 		 * ignoring.
178 		 */
179 		if (req->in_dpf != DPF_IGNORE)
180 			req->count++;
181 	}
182 	return (AE_OK);
183 }
184 
185 static ACPI_STATUS
186 link_add_crs(ACPI_RESOURCE *res, void *context)
187 {
188 	struct link_res_request *req;
189 	struct link *link;
190 
191 	req = (struct link_res_request *)context;
192 	switch (res->Type) {
193 	case ACPI_RESOURCE_TYPE_START_DEPENDENT:
194 		switch (req->in_dpf) {
195 		case DPF_OUTSIDE:
196 			/* We've started the first DPF. */
197 			req->in_dpf = DPF_FIRST;
198 			break;
199 		case DPF_FIRST:
200 			/* We've started the second DPF. */
201 			panic(
202 		"%s: Multiple dependent functions within a current resource",
203 			    __func__);
204 			break;
205 		}
206 		break;
207 	case ACPI_RESOURCE_TYPE_END_DEPENDENT:
208 		/* We are finished with DPF parsing. */
209 		KASSERT(req->in_dpf != DPF_OUTSIDE);
210 		req->in_dpf = DPF_OUTSIDE;
211 		break;
212 	case ACPI_RESOURCE_TYPE_IRQ:
213 	case ACPI_RESOURCE_TYPE_EXTENDED_IRQ:
214 		KASSERT(req->link_index < req->sc->pl_num_links);
215 		link = &req->sc->pl_links[req->link_index];
216 		link->l_res_index = req->res_index;
217 		req->link_index++;
218 		req->res_index++;
219 
220 		/*
221 		 * Only use the current value if there's one IRQ.  Some
222 		 * systems return multiple IRQs (which is nonsense for _CRS)
223 		 * when the link hasn't been programmed.
224 		 */
225 		if (res->Type == ACPI_RESOURCE_TYPE_IRQ) {
226 			if (res->Data.Irq.InterruptCount == 1) {
227 				link->l_irq = res->Data.Irq.Interrupts[0];
228 				link->l_trig = res->Data.Irq.Triggering;
229 				link->l_pol = res->Data.Irq.Polarity;
230 		}
231 		} else if (res->Data.ExtendedIrq.InterruptCount == 1) {
232 			link->l_irq = res->Data.ExtendedIrq.Interrupts[0];
233 			link->l_trig = res->Data.ExtendedIrq.Triggering;
234 			link->l_pol = res->Data.ExtendedIrq.Polarity;
235 		}
236 
237 		/*
238 		 * An IRQ of zero means that the link isn't routed.
239 		 */
240 		if (link->l_irq == 0)
241 			link->l_irq = PCI_INVALID_IRQ;
242 		break;
243 	default:
244 		req->res_index++;
245 	}
246 	return (AE_OK);
247 }
248 
249 /*
250  * Populate the set of possible IRQs for each device.
251  */
252 static ACPI_STATUS
253 link_add_prs(ACPI_RESOURCE *res, void *context)
254 {
255 	struct link_res_request *req;
256 	struct link *link;
257 	UINT8 *irqs = NULL;
258 	UINT32 *ext_irqs = NULL;
259 	int i, is_ext_irq = 1;
260 
261 	req = (struct link_res_request *)context;
262 	switch (res->Type) {
263 	case ACPI_RESOURCE_TYPE_START_DEPENDENT:
264 		switch (req->in_dpf) {
265 		case DPF_OUTSIDE:
266 			/* We've started the first DPF. */
267 			req->in_dpf = DPF_FIRST;
268 			break;
269 		case DPF_FIRST:
270 			/* We've started the second DPF. */
271 			req->in_dpf = DPF_IGNORE;
272 			break;
273 		}
274 		break;
275 	case ACPI_RESOURCE_TYPE_END_DEPENDENT:
276 		/* We are finished with DPF parsing. */
277 		KASSERT(req->in_dpf != DPF_OUTSIDE);
278 		req->in_dpf = DPF_OUTSIDE;
279 		break;
280 	case ACPI_RESOURCE_TYPE_IRQ:
281 		is_ext_irq = 0;
282 		/* fall through */
283 	case ACPI_RESOURCE_TYPE_EXTENDED_IRQ:
284 		/*
285 		 * Don't parse resources if we are in a DPF set that we are
286 		 * ignoring.
287 		 */
288 		if (req->in_dpf == DPF_IGNORE)
289 			break;
290 
291 		KASSERT(req->link_index < req->sc->pl_num_links);
292 		link = &req->sc->pl_links[req->link_index];
293 		if (link->l_res_index == -1) {
294 			KASSERT(req->sc->pl_crs_bad);
295 			link->l_res_index = req->res_index;
296 		}
297 		req->link_index++;
298 		req->res_index++;
299 
300 		/*
301 		 * Stash a copy of the resource for later use when
302 		 * doing _SRS.
303 		 *
304 		 * Note that in theory res->Length may exceed the size
305 		 * of ACPI_RESOURCE, due to variable length lists in
306 		 * subtypes.  However, all uses of l_prs_template only
307 		 * rely on lists lengths of zero or one, for which
308 		 * sizeof(ACPI_RESOURCE) is sufficient space anyway.
309 		 * We cannot read longer than Length bytes, in case we
310 		 * read off the end of mapped memory.  So we read
311 		 * whichever length is shortest, Length or
312 		 * sizeof(ACPI_RESOURCE).
313 		 */
314 		KASSERT(res->Length >= ACPI_RS_SIZE_MIN);
315 
316 		memset(&link->l_prs_template, 0, sizeof(link->l_prs_template));
317 		memcpy(&link->l_prs_template, res,
318 		       MIN(res->Length, sizeof(link->l_prs_template)));
319 
320 		if (is_ext_irq) {
321 			link->l_num_irqs =
322 			    res->Data.ExtendedIrq.InterruptCount;
323 			link->l_trig = res->Data.ExtendedIrq.Triggering;
324 			link->l_pol = res->Data.ExtendedIrq.Polarity;
325 			ext_irqs = res->Data.ExtendedIrq.Interrupts;
326 		} else {
327 			link->l_num_irqs = res->Data.Irq.InterruptCount;
328 			link->l_trig = res->Data.Irq.Triggering;
329 			link->l_pol = res->Data.Irq.Polarity;
330 			irqs = res->Data.Irq.Interrupts;
331 		}
332 		if (link->l_num_irqs == 0)
333 			break;
334 
335 		/*
336 		 * Save a list of the valid IRQs.  Also, if all of the
337 		 * valid IRQs are ISA IRQs, then mark this link as
338 		 * routed via an ISA interrupt.
339 		 */
340 		link->l_isa_irq = TRUE;
341 		link->l_irqs = malloc(sizeof(int) * link->l_num_irqs,
342 		    M_PCI_LINK, M_WAITOK | M_ZERO);
343 		for (i = 0; i < link->l_num_irqs; i++) {
344 			if (is_ext_irq) {
345 				link->l_irqs[i] = ext_irqs[i];
346 				if (ext_irqs[i] >= NUM_ISA_INTERRUPTS)
347 					link->l_isa_irq = FALSE;
348 			} else {
349 				link->l_irqs[i] = irqs[i];
350 				if (irqs[i] >= NUM_ISA_INTERRUPTS)
351 					link->l_isa_irq = FALSE;
352 			}
353 		}
354 		break;
355 	default:
356 		if (req->in_dpf == DPF_IGNORE)
357 			break;
358 		if (req->sc->pl_crs_bad)
359 			aprint_normal("%s: Warning: possible resource %d "
360 			       "will be lost during _SRS\n", req->sc->pl_name,
361 			       req->res_index);
362 		req->res_index++;
363 	}
364 	return (AE_OK);
365 }
366 
367 static int
368 link_valid_irq(struct link *link, int irq)
369 {
370 	int i;
371 
372 	/* Invalid interrupts are never valid. */
373 	if (!PCI_INTERRUPT_VALID(irq))
374 		return (FALSE);
375 
376 	/* Any interrupt in the list of possible interrupts is valid. */
377 	for (i = 0; i < link->l_num_irqs; i++)
378 		if (link->l_irqs[i] == irq)
379 			 return (TRUE);
380 
381 	/*
382 	 * For links routed via an ISA interrupt, if the SCI is routed via
383 	 * an ISA interrupt, the SCI is always treated as a valid IRQ.
384 	 */
385 	if (link->l_isa_irq && AcpiGbl_FADT->SciInt == irq &&
386 	    irq < NUM_ISA_INTERRUPTS)
387 		return (TRUE);
388 
389 	/* If the interrupt wasn't found in the list it is not valid. */
390 	return (FALSE);
391 }
392 
393 void
394 acpi_pci_link_state(void)
395 {
396 	struct acpi_pci_link_softc *sc;
397 
398 	TAILQ_FOREACH(sc, &acpi_pci_linkdevs, pl_list) {
399 		acpi_pci_link_dump(sc);
400 	}
401 }
402 
403 static void
404 acpi_pci_link_dump(struct acpi_pci_link_softc *sc)
405 {
406 	struct link *link;
407 	int i, j;
408 
409 	printf("Link Device %s:\n", sc->pl_name);
410 	printf("Index  IRQ  Rtd  Ref  IRQs\n");
411 	for (i = 0; i < sc->pl_num_links; i++) {
412 		link = &sc->pl_links[i];
413 		printf("%5d  %3d   %c   %3d ", i, link->l_irq,
414 		    link->l_routed ? 'Y' : 'N',  link->l_references);
415 		if (link->l_num_irqs == 0)
416 			printf(" none");
417 		else for (j = 0; j < link->l_num_irqs; j++)
418 			printf(" %d", link->l_irqs[j]);
419 		printf(" polarity %u trigger %u\n", link->l_pol, link->l_trig);
420 	}
421 	printf("\n");
422 }
423 
424 static int
425 acpi_pci_link_attach(struct acpi_pci_link_softc *sc)
426 {
427 	struct link_count_request creq;
428 	struct link_res_request rreq;
429 	ACPI_STATUS status;
430 	int i;
431 
432 	ACPI_SERIAL_BEGIN(pci_link);
433 
434 	/*
435 	 * Count the number of current resources so we know how big of
436 	 * a link array to allocate.  On some systems, _CRS is broken,
437 	 * so for those systems try to derive the count from _PRS instead.
438 	 */
439 	creq.in_dpf = DPF_OUTSIDE;
440 	creq.count = 0;
441 	status = AcpiWalkResources(sc->pl_handle, "_CRS",
442 	    acpi_count_irq_resources, &creq);
443 	sc->pl_crs_bad = ACPI_FAILURE(status);
444 	if (sc->pl_crs_bad) {
445 		creq.in_dpf = DPF_OUTSIDE;
446 		creq.count = 0;
447 		status = AcpiWalkResources(sc->pl_handle, "_PRS",
448 		    acpi_count_irq_resources, &creq);
449 		if (ACPI_FAILURE(status)) {
450 			aprint_error("%s: Unable to parse _CRS or _PRS: %s\n",
451 			    sc->pl_name, AcpiFormatException(status));
452 			ACPI_SERIAL_END(pci_link);
453 			return (ENXIO);
454 		}
455 	}
456 	sc->pl_num_links = creq.count;
457 	if (creq.count == 0) {
458 		ACPI_SERIAL_END(pci_link);
459 		return (0);
460 	}
461 	sc->pl_links = malloc(sizeof(struct link) * sc->pl_num_links,
462 	    M_PCI_LINK, M_WAITOK | M_ZERO);
463 
464 	/* Initialize the child links. */
465 	for (i = 0; i < sc->pl_num_links; i++) {
466 		sc->pl_links[i].l_irq = PCI_INVALID_IRQ;
467 		sc->pl_links[i].l_bios_irq = PCI_INVALID_IRQ;
468 		sc->pl_links[i].l_sc = sc;
469 		sc->pl_links[i].l_isa_irq = FALSE;
470 		sc->pl_links[i].l_res_index = -1;
471 	}
472 
473 	/* Try to read the current settings from _CRS if it is valid. */
474 	if (!sc->pl_crs_bad) {
475 		rreq.in_dpf = DPF_OUTSIDE;
476 		rreq.link_index = 0;
477 		rreq.res_index = 0;
478 		rreq.sc = sc;
479 		status = AcpiWalkResources(sc->pl_handle, "_CRS",
480 		    link_add_crs, &rreq);
481 		if (ACPI_FAILURE(status)) {
482 			aprint_error("%s: Unable to parse _CRS: %s\n",
483 			    sc->pl_name, AcpiFormatException(status));
484 			goto fail;
485 		}
486 	}
487 
488 	/*
489 	 * Try to read the possible settings from _PRS.  Note that if the
490 	 * _CRS is toast, we depend on having a working _PRS.  However, if
491 	 * _CRS works, then it is ok for _PRS to be missing.
492 	 */
493 	rreq.in_dpf = DPF_OUTSIDE;
494 	rreq.link_index = 0;
495 	rreq.res_index = 0;
496 	rreq.sc = sc;
497 	status = AcpiWalkResources(sc->pl_handle, "_PRS",
498 	    link_add_prs, &rreq);
499 	if (ACPI_FAILURE(status) &&
500 	    (status != AE_NOT_FOUND || sc->pl_crs_bad)) {
501 		aprint_error("%s: Unable to parse _PRS: %s\n",
502 		    sc->pl_name, AcpiFormatException(status));
503 		goto fail;
504 	}
505 	if (boothowto & AB_VERBOSE) {
506 		aprint_normal("%s: Links after initial probe:\n", sc->pl_name);
507 		acpi_pci_link_dump(sc);
508 	}
509 
510 	/* Verify initial IRQs if we have _PRS. */
511 	if (status != AE_NOT_FOUND)
512 		for (i = 0; i < sc->pl_num_links; i++)
513 			if (!link_valid_irq(&sc->pl_links[i],
514 			    sc->pl_links[i].l_irq))
515 				sc->pl_links[i].l_irq = PCI_INVALID_IRQ;
516 	if (boothowto & AB_VERBOSE) {
517 		printf("%s: Links after initial validation:\n", sc->pl_name);
518 		acpi_pci_link_dump(sc);
519 	}
520 
521 	/* Save initial IRQs. */
522 	for (i = 0; i < sc->pl_num_links; i++)
523 		sc->pl_links[i].l_initial_irq = sc->pl_links[i].l_irq;
524 
525 	/*
526 	 * Try to disable this link.  If successful, set the current IRQ to
527 	 * zero and flags to indicate this link is not routed.  If we can't
528 	 * run _DIS (i.e., the method doesn't exist), assume the initial
529 	 * IRQ was routed by the BIOS.
530 	 */
531 #if 0	/* XXX causes spontaneaous resets on some systems. Disabled for now. */
532 	if (ACPI_SUCCESS(AcpiEvaluateObject(sc->pl_handle, "_DIS", NULL,
533 	    NULL)))
534 		for (i = 0; i < sc->pl_num_links; i++)
535 			sc->pl_links[i].l_irq = PCI_INVALID_IRQ;
536 	else
537 #endif
538 		for (i = 0; i < sc->pl_num_links; i++)
539 			if (PCI_INTERRUPT_VALID(sc->pl_links[i].l_irq))
540 				sc->pl_links[i].l_routed = TRUE;
541 	if (boothowto & AB_VERBOSE) {
542 		printf("%s: Links after disable:\n", sc->pl_name);
543 		acpi_pci_link_dump(sc);
544 	}
545 	ACPI_SERIAL_END(pci_link);
546 	return (0);
547 fail:
548 	ACPI_SERIAL_END(pci_link);
549 	for (i = 0; i < sc->pl_num_links; i++)
550 		if (sc->pl_links[i].l_irqs != NULL)
551 			free(sc->pl_links[i].l_irqs, M_PCI_LINK);
552 	free(sc->pl_links, M_PCI_LINK);
553 	return (ENXIO);
554 }
555 
556 static uint8_t
557 acpi_pci_link_search_irq(struct acpi_pci_link_softc *sc, int bus, int device,
558 			 int pin)
559 {
560 	uint32_t value;
561 	uint8_t func, maxfunc, ipin, iline;
562 	pcitag_t tag;
563 
564 	tag = pci_make_tag(acpi_softc->sc_pc, bus, device, 0);
565 	/* See if we have a valid device at function 0. */
566 	value = pci_conf_read(acpi_softc->sc_pc, tag,  PCI_BHLC_REG);
567 	if (PCI_HDRTYPE_TYPE(value) > PCI_HDRTYPE_PCB)
568 		return (PCI_INVALID_IRQ);
569 	if (PCI_HDRTYPE_MULTIFN(value))
570 		maxfunc = 7;
571 	else
572 		maxfunc = 0;
573 
574 	/* Scan all possible functions at this device. */
575 	for (func = 0; func <= maxfunc; func++) {
576 		tag = pci_make_tag(acpi_softc->sc_pc, bus, device, func);
577 		value = pci_conf_read(acpi_softc->sc_pc, tag, PCI_ID_REG);
578 		if (PCI_VENDOR(value) == 0xffff)
579 			continue;
580 		value = pci_conf_read(acpi_softc->sc_pc, tag,
581 		    PCI_INTERRUPT_REG);
582 		ipin = PCI_INTERRUPT_PIN(value);
583 		iline = PCI_INTERRUPT_LINE(value);
584 
585 		/*
586 		 * See if it uses the pin in question.  Note that the passed
587 		 * in pin uses 0 for A, .. 3 for D whereas the intpin
588 		 * register uses 0 for no interrupt, 1 for A, .. 4 for D.
589 		 */
590 		if (ipin != pin + 1)
591 			continue;
592 		aprint_verbose(
593 		    "%s: ACPI: Found matching pin for %d.%d.INT%c"
594 	            " at func %d: %d\n",
595 			    sc->pl_name, bus, device, pin + 'A', func, iline);
596 		if (PCI_INTERRUPT_VALID(iline))
597 			return (iline);
598 	}
599 	return (PCI_INVALID_IRQ);
600 }
601 
602 /*
603  * Find the link structure that corresponds to the resource index passed in
604  * via 'source_index'.
605  */
606 static struct link *
607 acpi_pci_link_lookup(struct acpi_pci_link_softc *sc, int source_index)
608 {
609 	int i;
610 
611 	for (i = 0; i < sc->pl_num_links; i++)
612 		if (sc->pl_links[i].l_res_index == source_index)
613 			return (&sc->pl_links[i]);
614 	return (NULL);
615 }
616 
617 void
618 acpi_pci_link_add_reference(void *v, int index, int bus, int slot, int pin)
619 {
620 	struct acpi_pci_link_softc *sc = v;
621 	struct link *link;
622 	uint8_t bios_irq;
623 
624 	/* Bump the reference count. */
625 	ACPI_SERIAL_BEGIN(pci_link);
626 	link = acpi_pci_link_lookup(sc, index);
627 	if (link == NULL) {
628 		printf("%s: apparently invalid index %d\n", sc->pl_name, index);
629 		ACPI_SERIAL_END(pci_link);
630 		return;
631 	}
632 	link->l_references++;
633 	if (link->l_routed)
634 		pci_link_interrupt_weights[link->l_irq]++;
635 
636 	/*
637 	 * The BIOS only routes interrupts via ISA IRQs using the ATPICs
638 	 * (8259As).  Thus, if this link is routed via an ISA IRQ, go
639 	 * look to see if the BIOS routed an IRQ for this link at the
640 	 * indicated (bus, slot, pin).  If so, we prefer that IRQ for
641 	 * this link and add that IRQ to our list of known-good IRQs.
642 	 * This provides a good work-around for link devices whose _CRS
643 	 * method is either broken or bogus.  We only use the value
644 	 * returned by _CRS if we can't find a valid IRQ via this method
645 	 * in fact.
646 	 *
647 	 * If this link is not routed via an ISA IRQ (because we are using
648 	 * APIC for example), then don't bother looking up the BIOS IRQ
649 	 * as if we find one it won't be valid anyway.
650 	 */
651 	if (!link->l_isa_irq) {
652 		ACPI_SERIAL_END(pci_link);
653 		return;
654 	}
655 
656 	/* Try to find a BIOS IRQ setting from any matching devices. */
657 	bios_irq = acpi_pci_link_search_irq(sc, bus, slot, pin);
658 	if (!PCI_INTERRUPT_VALID(bios_irq)) {
659 		ACPI_SERIAL_END(pci_link);
660 		return;
661 	}
662 
663 	/* Validate the BIOS IRQ. */
664 	if (!link_valid_irq(link, bios_irq)) {
665 		printf("%s: BIOS IRQ %u for %d.%d.INT%c is invalid\n",
666 		    sc->pl_name, bios_irq, (int)bus, slot, pin + 'A');
667 	} else if (!PCI_INTERRUPT_VALID(link->l_bios_irq)) {
668 		link->l_bios_irq = bios_irq;
669 		if (bios_irq < NUM_ISA_INTERRUPTS)
670 			pci_link_bios_isa_irqs |= (1 << bios_irq);
671 		if (bios_irq != link->l_initial_irq &&
672 		    PCI_INTERRUPT_VALID(link->l_initial_irq))
673 			printf(
674 			    "%s: BIOS IRQ %u does not match initial IRQ %u\n",
675 			    sc->pl_name, bios_irq, link->l_initial_irq);
676 	} else if (bios_irq != link->l_bios_irq)
677 		printf(
678 	    "%s: BIOS IRQ %u for %d.%d.INT%c does not match "
679 	    "previous BIOS IRQ %u\n",
680 		    sc->pl_name, bios_irq, (int)bus, slot, pin + 'A',
681 		    link->l_bios_irq);
682 	ACPI_SERIAL_END(pci_link);
683 }
684 
685 static ACPI_STATUS
686 acpi_pci_link_srs_from_crs(struct acpi_pci_link_softc *sc, ACPI_BUFFER *srsbuf)
687 {
688 	ACPI_RESOURCE *resource, *end, newres, *resptr;
689 	ACPI_BUFFER crsbuf;
690 	ACPI_STATUS status;
691 	struct link *link;
692 	int i, in_dpf;
693 
694 	/* Fetch the _CRS. */
695 	crsbuf.Pointer = NULL;
696 	crsbuf.Length = ACPI_ALLOCATE_BUFFER;
697 	status = AcpiGetCurrentResources(sc->pl_handle, &crsbuf);
698 	if (ACPI_SUCCESS(status) && crsbuf.Pointer == NULL)
699 		status = AE_NO_MEMORY;
700 	if (ACPI_FAILURE(status)) {
701 		aprint_verbose("%s: Unable to fetch current resources: %s\n",
702 		    sc->pl_name, AcpiFormatException(status));
703 		return (status);
704 	}
705 
706 	/* Fill in IRQ resources via link structures. */
707 	srsbuf->Pointer = NULL;
708 	link = sc->pl_links;
709 	i = 0;
710 	in_dpf = DPF_OUTSIDE;
711 	resource = (ACPI_RESOURCE *)crsbuf.Pointer;
712 	end = (ACPI_RESOURCE *)((char *)crsbuf.Pointer + crsbuf.Length);
713 	for (;;) {
714 		switch (resource->Type) {
715 		case ACPI_RESOURCE_TYPE_START_DEPENDENT:
716 			switch (in_dpf) {
717 			case DPF_OUTSIDE:
718 				/* We've started the first DPF. */
719 				in_dpf = DPF_FIRST;
720 				break;
721 			case DPF_FIRST:
722 				/* We've started the second DPF. */
723 				panic(
724 		"%s: Multiple dependent functions within a current resource",
725 				    __func__);
726 				break;
727 			}
728 			resptr = NULL;
729 			break;
730 		case ACPI_RESOURCE_TYPE_END_DEPENDENT:
731 			/* We are finished with DPF parsing. */
732 			KASSERT(in_dpf != DPF_OUTSIDE);
733 			in_dpf = DPF_OUTSIDE;
734 			resptr = NULL;
735 			break;
736 		case ACPI_RESOURCE_TYPE_IRQ:
737 			newres = link->l_prs_template;
738 			resptr = &newres;
739 			resptr->Data.Irq.InterruptCount = 1;
740 			if (PCI_INTERRUPT_VALID(link->l_irq)) {
741 				KASSERT(link->l_irq < NUM_ISA_INTERRUPTS);
742 				resptr->Data.Irq.Interrupts[0] = link->l_irq;
743 				resptr->Data.Irq.Triggering = link->l_trig;
744 				resptr->Data.Irq.Polarity = link->l_pol;
745 			} else
746 				resptr->Data.Irq.Interrupts[0] = 0;
747 			link++;
748 			i++;
749 			break;
750 		case ACPI_RESOURCE_TYPE_EXTENDED_IRQ:
751 			newres = link->l_prs_template;
752 			resptr = &newres;
753 			resptr->Data.ExtendedIrq.InterruptCount = 1;
754 			if (PCI_INTERRUPT_VALID(link->l_irq)) {
755 				resptr->Data.ExtendedIrq.Interrupts[0] =
756 				    link->l_irq;
757 				resptr->Data.ExtendedIrq.Triggering =
758 				    link->l_trig;
759 				resptr->Data.ExtendedIrq.Polarity = link->l_pol;
760 			} else
761 				resptr->Data.ExtendedIrq.Interrupts[0] = 0;
762 			link++;
763 			i++;
764 			break;
765 		default:
766 			resptr = resource;
767 		}
768 		if (resptr != NULL) {
769 			status = acpi_AppendBufferResource(srsbuf, resptr);
770 			if (ACPI_FAILURE(status)) {
771 				printf("%s: Unable to build resources: %s\n",
772 				    sc->pl_name, AcpiFormatException(status));
773 				if (srsbuf->Pointer != NULL)
774 					AcpiOsFree(srsbuf->Pointer);
775 				AcpiOsFree(crsbuf.Pointer);
776 				return (status);
777 			}
778 		}
779 		if (resource->Type == ACPI_RESOURCE_TYPE_END_TAG)
780 			break;
781 		resource = ACPI_NEXT_RESOURCE(resource);
782 		if (resource >= end)
783 			break;
784 	}
785 	AcpiOsFree(crsbuf.Pointer);
786 	return (AE_OK);
787 }
788 
789 static ACPI_STATUS
790 acpi_pci_link_srs_from_links(struct acpi_pci_link_softc *sc,
791     ACPI_BUFFER *srsbuf)
792 {
793 	ACPI_RESOURCE newres;
794 	ACPI_STATUS status;
795 	struct link *link;
796 	int i;
797 
798 	/* Start off with an empty buffer. */
799 	srsbuf->Pointer = NULL;
800 	link = sc->pl_links;
801 	for (i = 0; i < sc->pl_num_links; i++) {
802 
803 		/* Add a new IRQ resource from each link. */
804 		link = &sc->pl_links[i];
805 		newres = link->l_prs_template;
806 		if (newres.Type == ACPI_RESOURCE_TYPE_IRQ) {
807 
808 			/* Build an IRQ resource. */
809 			newres.Data.Irq.InterruptCount = 1;
810 			if (PCI_INTERRUPT_VALID(link->l_irq)) {
811 				KASSERT(link->l_irq < NUM_ISA_INTERRUPTS);
812 				newres.Data.Irq.Interrupts[0] = link->l_irq;
813 				newres.Data.Irq.Triggering = link->l_trig;
814 				newres.Data.Irq.Polarity = link->l_pol;
815 			} else
816 				newres.Data.Irq.Interrupts[0] = 0;
817 		} else {
818 
819 			/* Build an ExtIRQ resuorce. */
820 			newres.Data.ExtendedIrq.InterruptCount = 1;
821 			if (PCI_INTERRUPT_VALID(link->l_irq)) {
822 				newres.Data.ExtendedIrq.Interrupts[0] =
823 				    link->l_irq;
824 				newres.Data.ExtendedIrq.Triggering =
825 				    link->l_trig;
826 				newres.Data.ExtendedIrq.Polarity =
827 				    link->l_pol;
828 			} else {
829 				newres.Data.ExtendedIrq.Interrupts[0] = 0;
830 			}
831 		}
832 
833 		/* Add the new resource to the end of the _SRS buffer. */
834 		status = acpi_AppendBufferResource(srsbuf, &newres);
835 		if (ACPI_FAILURE(status)) {
836 			printf("%s: Unable to build resources: %s\n",
837 			    sc->pl_name, AcpiFormatException(status));
838 			if (srsbuf->Pointer != NULL)
839 				AcpiOsFree(srsbuf->Pointer);
840 			return (status);
841 		}
842 	}
843 	return (AE_OK);
844 }
845 
846 static ACPI_STATUS
847 acpi_pci_link_srs(struct acpi_pci_link_softc *sc, ACPI_BUFFER *srsbuf)
848 {
849 	ACPI_STATUS status;
850 
851 	if (sc->pl_crs_bad)
852 		status = acpi_pci_link_srs_from_links(sc, srsbuf);
853 	else
854 		status = acpi_pci_link_srs_from_crs(sc, srsbuf);
855 
856 	/* Write out new resources via _SRS. */
857 	return AcpiSetCurrentResources(sc->pl_handle, srsbuf);
858 }
859 
860 static ACPI_STATUS
861 acpi_pci_link_route_irqs(struct acpi_pci_link_softc *sc, int *irq, int *pol,
862 			 int *trig)
863 {
864 	ACPI_RESOURCE *resource, *end;
865 	ACPI_BUFFER srsbuf;
866 	ACPI_STATUS status;
867 	struct link *link;
868 	int i, is_ext = 0;
869 
870 	status = acpi_pci_link_srs(sc, &srsbuf);
871 	if (ACPI_FAILURE(status)) {
872 		printf("%s: _SRS failed: %s\n",
873 		    sc->pl_name, AcpiFormatException(status));
874 		return (status);
875 	}
876 	/*
877 	 * Perform acpi_config_intr() on each IRQ resource if it was just
878 	 * routed for the first time.
879 	 */
880 	link = sc->pl_links;
881 	i = 0;
882 	resource = (ACPI_RESOURCE *)srsbuf.Pointer;
883 	end = (ACPI_RESOURCE *)((char *)srsbuf.Pointer + srsbuf.Length);
884 	for (;;) {
885 		if (resource->Type == ACPI_RESOURCE_TYPE_END_TAG)
886 			break;
887 		switch (resource->Type) {
888 		case ACPI_RESOURCE_TYPE_EXTENDED_IRQ:
889 			is_ext = 1;
890 			/* FALLTHROUGH */
891 		case ACPI_RESOURCE_TYPE_IRQ:
892 			/*
893 			 * Only configure the interrupt and update the
894 			 * weights if this link has a valid IRQ and was
895 			 * previously unrouted.
896 			 */
897 			if (!link->l_routed &&
898 			    PCI_INTERRUPT_VALID(link->l_irq)) {
899 				*trig = is_ext ?
900 				    resource->Data.ExtendedIrq.Triggering :
901 				    resource->Data.Irq.Triggering;
902 				*pol = is_ext ?
903 				    resource->Data.ExtendedIrq.Polarity :
904 				    resource->Data.Irq.Polarity;
905 				*irq = is_ext ?
906 				    resource->Data.ExtendedIrq.Interrupts[0] :
907 				    resource->Data.Irq.Interrupts[0];
908 				link->l_routed = TRUE;
909 				pci_link_interrupt_weights[link->l_irq] +=
910 				    link->l_references;
911 			}
912 			link++;
913 			i++;
914 			break;
915 		}
916 		resource = ACPI_NEXT_RESOURCE(resource);
917 		if (resource >= end)
918 			break;
919 	}
920 	AcpiOsFree(srsbuf.Pointer);
921 	return (AE_OK);
922 }
923 
924 static void
925 acpi_pci_link_resume(int why, void *arg)
926 {
927 	struct acpi_pci_link_softc *sc = arg;
928 	ACPI_BUFFER srsbuf;
929 
930 	switch (why) {
931 	case PWR_RESUME:
932 		ACPI_SERIAL_BEGIN(pci_link);
933 		if (ACPI_SUCCESS(acpi_pci_link_srs(sc, &srsbuf)))
934 			AcpiOsFree(srsbuf.Pointer);
935 		ACPI_SERIAL_END(pci_link);
936 	default:
937 		break;
938 	}
939 }
940 
941 /*
942  * Pick an IRQ to use for this unrouted link.
943  */
944 static uint8_t
945 acpi_pci_link_choose_irq(struct acpi_pci_link_softc *sc, struct link *link)
946 {
947 	u_int8_t best_irq, pos_irq;
948 	int best_weight, pos_weight, i;
949 
950 	KASSERT(!link->l_routed);
951 	KASSERT(!PCI_INTERRUPT_VALID(link->l_irq));
952 
953 	/*
954 	 * If we have a valid BIOS IRQ, use that.  We trust what the BIOS
955 	 * says it routed over what _CRS says the link thinks is routed.
956 	 */
957 	if (PCI_INTERRUPT_VALID(link->l_bios_irq))
958 		return (link->l_bios_irq);
959 
960 	/*
961 	 * If we don't have a BIOS IRQ but do have a valid IRQ from _CRS,
962 	 * then use that.
963 	 */
964 	if (PCI_INTERRUPT_VALID(link->l_initial_irq))
965 		return (link->l_initial_irq);
966 
967 	/*
968 	 * Ok, we have no useful hints, so we have to pick from the
969 	 * possible IRQs.  For ISA IRQs we only use interrupts that
970 	 * have already been used by the BIOS.
971 	 */
972 	best_irq = PCI_INVALID_IRQ;
973 	best_weight = INT_MAX;
974 	for (i = 0; i < link->l_num_irqs; i++) {
975 		pos_irq = link->l_irqs[i];
976 		if (pos_irq < NUM_ISA_INTERRUPTS &&
977 		    (pci_link_bios_isa_irqs & 1 << pos_irq) == 0)
978 			continue;
979 		pos_weight = pci_link_interrupt_weights[pos_irq];
980 		if (pos_weight < best_weight) {
981 			best_weight = pos_weight;
982 			best_irq = pos_irq;
983 		}
984 	}
985 
986 	/*
987 	 * If this is an ISA IRQ, try using the SCI if it is also an ISA
988 	 * interrupt as a fallback.
989 	 */
990 	if (link->l_isa_irq) {
991 		pos_irq = AcpiGbl_FADT->SciInt;
992 		pos_weight = pci_link_interrupt_weights[pos_irq];
993 		if (pos_weight < best_weight) {
994 			best_weight = pos_weight;
995 			best_irq = pos_irq;
996 		}
997 	}
998 
999 	if (PCI_INTERRUPT_VALID(best_irq)) {
1000 		aprint_verbose("%s: Picked IRQ %u with weight %d\n",
1001 		    sc->pl_name, best_irq, best_weight);
1002 	} else
1003 		printf("%s: Unable to choose an IRQ\n", sc->pl_name);
1004 	return (best_irq);
1005 }
1006 
1007 int
1008 acpi_pci_link_route_interrupt(void *v, int index, int *irq, int *pol, int *trig)
1009 {
1010 	struct acpi_pci_link_softc *sc = v;
1011 	struct link *link;
1012 
1013 	ACPI_SERIAL_BEGIN(pci_link);
1014 	link = acpi_pci_link_lookup(sc, index);
1015 	if (link == NULL)
1016 		panic("%s: apparently invalid index %d", __func__, index);
1017 
1018 	/*
1019 	 * If this link device is already routed to an interrupt, just return
1020 	 * the interrupt it is routed to.
1021 	 */
1022 	if (link->l_routed) {
1023 		KASSERT(PCI_INTERRUPT_VALID(link->l_irq));
1024 		ACPI_SERIAL_END(pci_link);
1025 		*irq = link->l_irq;
1026 		*pol = link->l_pol;
1027 		*trig = link->l_trig;
1028 		return (link->l_irq);
1029 	}
1030 
1031 	/* Choose an IRQ if we need one. */
1032 	if (!PCI_INTERRUPT_VALID(link->l_irq)) {
1033 		link->l_irq = acpi_pci_link_choose_irq(sc, link);
1034 
1035 		/*
1036 		 * Try to route the interrupt we picked.  If it fails, then
1037 		 * assume the interrupt is not routed.
1038 		 */
1039 		if (PCI_INTERRUPT_VALID(link->l_irq)) {
1040 			acpi_pci_link_route_irqs(sc, irq, pol, trig);
1041 			if (!link->l_routed)
1042 				link->l_irq = PCI_INVALID_IRQ;
1043 			else {
1044 				link->l_pol = *pol;
1045 				link->l_trig = *trig;
1046 			}
1047 		}
1048 	}
1049 	ACPI_SERIAL_END(pci_link);
1050 
1051 	return (link->l_irq);
1052 }
1053 
1054 /*
1055  * This is gross, but we abuse the identify routine to perform one-time
1056  * SYSINIT() style initialization for the driver.
1057  */
1058 static void
1059 acpi_pci_link_init(struct acpi_pci_link_softc *sc)
1060 {
1061 	ACPI_BUFFER buf;
1062 
1063 	/*
1064 	 * If the SCI is an ISA IRQ, add it to the bitmask of known good
1065 	 * ISA IRQs.
1066 	 *
1067 	 * XXX: If we are using the APIC, the SCI might have been
1068 	 * rerouted to an APIC pin in which case this is invalid.  However,
1069 	 * if we are using the APIC, we also shouldn't be having any PCI
1070 	 * interrupts routed via ISA IRQs, so this is probably ok.
1071 	 */
1072 	if (AcpiGbl_FADT->SciInt < NUM_ISA_INTERRUPTS)
1073 		pci_link_bios_isa_irqs |= (1 << AcpiGbl_FADT->SciInt);
1074 
1075         sc->pl_powerhook = powerhook_establish(acpi_pci_link_resume, sc);
1076         if (sc->pl_powerhook == NULL)
1077                 aprint_normal("can't establish powerhook\n");
1078 
1079 	buf.Length = sizeof (sc->pl_name);
1080 	buf.Pointer = sc->pl_name;
1081 
1082 	if (ACPI_FAILURE(AcpiGetName(sc->pl_handle, ACPI_SINGLE_NAME, &buf)))
1083 		snprintf(sc->pl_name, sizeof (sc->pl_name), "%s",
1084 		    "ACPI link device");
1085 
1086 	acpi_pci_link_attach(sc);
1087 }
1088 
1089 void *
1090 acpi_pci_link_devbyhandle(ACPI_HANDLE handle)
1091 {
1092 	struct acpi_pci_link_softc *sc;
1093 
1094 	TAILQ_FOREACH(sc, &acpi_pci_linkdevs, pl_list) {
1095 		if (sc->pl_handle == handle)
1096 			return sc;
1097 	}
1098 
1099 	sc = malloc(sizeof (*sc), M_PCI_LINK, M_NOWAIT|M_ZERO);
1100 	if (sc == NULL)
1101 		return NULL;
1102 
1103 	sc->pl_handle = handle;
1104 
1105 	acpi_pci_link_init(sc);
1106 
1107 	TAILQ_INSERT_TAIL(&acpi_pci_linkdevs, sc, pl_list);
1108 
1109 	return (void *)sc;
1110 }
1111 
1112 ACPI_HANDLE
1113 acpi_pci_link_handle(void *v)
1114 {
1115 	struct acpi_pci_link_softc *sc = v;
1116 
1117 	return sc->pl_handle;
1118 }
1119 
1120 char *
1121 acpi_pci_link_name(void *v)
1122 {
1123 	struct acpi_pci_link_softc *sc = v;
1124 
1125 	return sc->pl_name;
1126 }
1127 
1128 
1129 /*
1130  * Append an ACPI_RESOURCE to an ACPI_BUFFER.
1131  *
1132  * Given a pointer to an ACPI_RESOURCE structure, expand the ACPI_BUFFER
1133  * provided to contain it.  If the ACPI_BUFFER is empty, allocate a sensible
1134  * backing block.  If the ACPI_RESOURCE is NULL, return an empty set of
1135  * resources.
1136  */
1137 #define ACPI_INITIAL_RESOURCE_BUFFER_SIZE	512
1138 
1139 static ACPI_STATUS
1140 acpi_AppendBufferResource(ACPI_BUFFER *buf, ACPI_RESOURCE *res)
1141 {
1142 	ACPI_RESOURCE	*rp;
1143 	void		*newp;
1144 
1145 	/* Initialise the buffer if necessary. */
1146 	if (buf->Pointer == NULL) {
1147 	buf->Length = ACPI_INITIAL_RESOURCE_BUFFER_SIZE;
1148 	if ((buf->Pointer = AcpiOsAllocate(buf->Length)) == NULL)
1149 		return (AE_NO_MEMORY);
1150 	rp = (ACPI_RESOURCE *)buf->Pointer;
1151 	rp->Type =  ACPI_RESOURCE_TYPE_END_TAG;
1152 	rp->Length = 0;
1153 	}
1154 
1155 	if (res == NULL)
1156 		return (AE_OK);
1157 
1158 	/*
1159 	 * Scan the current buffer looking for the terminator.
1160 	 * This will either find the terminator or hit the end
1161 	 * of the buffer and return an error.
1162 	 */
1163 	rp = (ACPI_RESOURCE *)buf->Pointer;
1164 	for (;;) {
1165 		/* Range check, don't go outside the buffer */
1166 		if (rp >= (ACPI_RESOURCE *)((u_int8_t *)buf->Pointer +
1167 		    buf->Length))
1168 			return (AE_BAD_PARAMETER);
1169 		if (rp->Type ==  ACPI_RESOURCE_TYPE_END_TAG || rp->Length == 0)
1170 			break;
1171 		rp = ACPI_NEXT_RESOURCE(rp);
1172 	}
1173 
1174 	/*
1175 	 * Check the size of the buffer and expand if required.
1176 	 *
1177 	 * Required size is:
1178 	 *	size of existing resources before terminator +
1179 	 *	size of new resource and header +
1180 	 * 	size of terminator.
1181 	 *
1182 	 * Note that this loop should really only run once, unless
1183 	 * for some reason we are stuffing a *really* huge resource.
1184 	 */
1185 	while ((((u_int8_t *)rp - (u_int8_t *)buf->Pointer) +
1186 	    res->Length + ACPI_RS_SIZE_NO_DATA +
1187 	    ACPI_RS_SIZE_MIN) >= buf->Length) {
1188 		if ((newp = AcpiOsAllocate(buf->Length * 2)) == NULL)
1189 			return (AE_NO_MEMORY);
1190 		memcpy(newp, buf->Pointer, buf->Length);
1191 		rp = (ACPI_RESOURCE *)((u_int8_t *)newp +
1192 		   ((u_int8_t *)rp - (u_int8_t *)buf->Pointer));
1193 		AcpiOsFree(buf->Pointer);
1194 		buf->Pointer = newp;
1195 		buf->Length += buf->Length;
1196 	}
1197 
1198 	/* Insert the new resource. */
1199 	memcpy(rp, res, res->Length + ACPI_RS_SIZE_NO_DATA);
1200 
1201 	/* And add the terminator. */
1202 	rp = ACPI_NEXT_RESOURCE(rp);
1203 	rp->Type =  ACPI_RESOURCE_TYPE_END_TAG;
1204 	rp->Length = 0;
1205 
1206 	return (AE_OK);
1207 }
1208