xref: /freebsd/sys/dev/ofw/openfirm.c (revision af23369a6deaaeb612ab266eb88b8bb8d560c322)
1 /*	$NetBSD: Locore.c,v 1.7 2000/08/20 07:04:59 tsubai Exp $	*/
2 
3 /*-
4  * SPDX-License-Identifier: BSD-4-Clause
5  *
6  * Copyright (C) 1995, 1996 Wolfgang Solfrank.
7  * Copyright (C) 1995, 1996 TooLs GmbH.
8  * All rights reserved.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. All advertising materials mentioning features or use of this software
19  *    must display the following acknowledgement:
20  *	This product includes software developed by TooLs GmbH.
21  * 4. The name of TooLs GmbH may not be used to endorse or promote products
22  *    derived from this software without specific prior written permission.
23  *
24  * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
25  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
26  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
27  * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
28  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
29  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
30  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
31  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
32  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
33  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34  */
35 /*-
36  * Copyright (C) 2000 Benno Rice.
37  * All rights reserved.
38  *
39  * Redistribution and use in source and binary forms, with or without
40  * modification, are permitted provided that the following conditions
41  * are met:
42  * 1. Redistributions of source code must retain the above copyright
43  *    notice, this list of conditions and the following disclaimer.
44  * 2. Redistributions in binary form must reproduce the above copyright
45  *    notice, this list of conditions and the following disclaimer in the
46  *    documentation and/or other materials provided with the distribution.
47  *
48  * THIS SOFTWARE IS PROVIDED BY Benno Rice ``AS IS'' AND ANY EXPRESS OR
49  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
50  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
51  * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
52  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
53  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
54  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
55  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
56  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
57  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
58  */
59 
60 #include <sys/cdefs.h>
61 __FBSDID("$FreeBSD$");
62 
63 #include "opt_platform.h"
64 
65 #include <sys/param.h>
66 #include <sys/kernel.h>
67 #include <sys/lock.h>
68 #include <sys/malloc.h>
69 #include <sys/mutex.h>
70 #include <sys/queue.h>
71 #include <sys/systm.h>
72 #include <sys/endian.h>
73 
74 #include <machine/stdarg.h>
75 
76 #include <dev/ofw/ofwvar.h>
77 #include <dev/ofw/openfirm.h>
78 
79 #include "ofw_if.h"
80 
81 static void OF_putchar(int c, void *arg);
82 
83 MALLOC_DEFINE(M_OFWPROP, "openfirm", "Open Firmware properties");
84 
85 static ihandle_t stdout;
86 
87 static ofw_def_t	*ofw_def_impl = NULL;
88 static ofw_t		ofw_obj;
89 static struct ofw_kobj	ofw_kernel_obj;
90 static struct kobj_ops	ofw_kernel_kops;
91 
92 struct xrefinfo {
93 	phandle_t	xref;
94 	phandle_t 	node;
95 	device_t  	dev;
96 	SLIST_ENTRY(xrefinfo) next_entry;
97 };
98 
99 static SLIST_HEAD(, xrefinfo) xreflist = SLIST_HEAD_INITIALIZER(xreflist);
100 static struct mtx xreflist_lock;
101 static boolean_t xref_init_done;
102 
103 #define	FIND_BY_XREF	0
104 #define	FIND_BY_NODE	1
105 #define	FIND_BY_DEV	2
106 
107 /*
108  * xref-phandle-device lookup helper routines.
109  *
110  * As soon as we are able to use malloc(), walk the node tree and build a list
111  * of info that cross-references node handles, xref handles, and device_t
112  * instances.  This list exists primarily to allow association of a device_t
113  * with an xref handle, but it is also used to speed up translation between xref
114  * and node handles.  Before malloc() is available we have to recursively search
115  * the node tree each time we want to translate between a node and xref handle.
116  * Afterwards we can do the translations by searching this much shorter list.
117  */
118 static void
119 xrefinfo_create(phandle_t node)
120 {
121 	struct xrefinfo * xi;
122 	phandle_t child, xref;
123 
124 	/*
125 	 * Recursively descend from parent, looking for nodes with a property
126 	 * named either "phandle", "ibm,phandle", or "linux,phandle".  For each
127 	 * such node found create an entry in the xreflist.
128 	 */
129 	for (child = OF_child(node); child != 0; child = OF_peer(child)) {
130 		xrefinfo_create(child);
131 		if (OF_getencprop(child, "phandle", &xref, sizeof(xref)) ==
132 		    -1 && OF_getencprop(child, "ibm,phandle", &xref,
133 		    sizeof(xref)) == -1 && OF_getencprop(child,
134 		    "linux,phandle", &xref, sizeof(xref)) == -1)
135 			continue;
136 		xi = malloc(sizeof(*xi), M_OFWPROP, M_WAITOK | M_ZERO);
137 		xi->node = child;
138 		xi->xref = xref;
139 		SLIST_INSERT_HEAD(&xreflist, xi, next_entry);
140 	}
141 }
142 
143 static void
144 xrefinfo_init(void *unsed)
145 {
146 
147 	/*
148 	 * There is no locking during this init because it runs much earlier
149 	 * than any of the clients/consumers of the xref list data, but we do
150 	 * initialize the mutex that will be used for access later.
151 	 */
152 	mtx_init(&xreflist_lock, "OF xreflist lock", NULL, MTX_DEF);
153 	xrefinfo_create(OF_peer(0));
154 	xref_init_done = true;
155 }
156 SYSINIT(xrefinfo, SI_SUB_KMEM, SI_ORDER_ANY, xrefinfo_init, NULL);
157 
158 static struct xrefinfo *
159 xrefinfo_find(uintptr_t key, int find_by)
160 {
161 	struct xrefinfo *rv, *xi;
162 
163 	rv = NULL;
164 	mtx_lock(&xreflist_lock);
165 	SLIST_FOREACH(xi, &xreflist, next_entry) {
166 		if ((find_by == FIND_BY_XREF && (phandle_t)key == xi->xref) ||
167 		    (find_by == FIND_BY_NODE && (phandle_t)key == xi->node) ||
168 		    (find_by == FIND_BY_DEV && key == (uintptr_t)xi->dev)) {
169 			rv = xi;
170 			break;
171 		}
172 	}
173 	mtx_unlock(&xreflist_lock);
174 	return (rv);
175 }
176 
177 static struct xrefinfo *
178 xrefinfo_add(phandle_t node, phandle_t xref, device_t dev)
179 {
180 	struct xrefinfo *xi;
181 
182 	xi = malloc(sizeof(*xi), M_OFWPROP, M_WAITOK);
183 	xi->node = node;
184 	xi->xref = xref;
185 	xi->dev  = dev;
186 	mtx_lock(&xreflist_lock);
187 	SLIST_INSERT_HEAD(&xreflist, xi, next_entry);
188 	mtx_unlock(&xreflist_lock);
189 	return (xi);
190 }
191 
192 /*
193  * OFW install routines.  Highest priority wins, equal priority also
194  * overrides allowing last-set to win.
195  */
196 SET_DECLARE(ofw_set, ofw_def_t);
197 
198 boolean_t
199 OF_install(char *name, int prio)
200 {
201 	ofw_def_t *ofwp, **ofwpp;
202 	static int curr_prio = 0;
203 
204 	/* Allow OF layer to be uninstalled */
205 	if (name == NULL) {
206 		ofw_def_impl = NULL;
207 		return (FALSE);
208 	}
209 
210 	/*
211 	 * Try and locate the OFW kobj corresponding to the name.
212 	 */
213 	SET_FOREACH(ofwpp, ofw_set) {
214 		ofwp = *ofwpp;
215 
216 		if (ofwp->name &&
217 		    !strcmp(ofwp->name, name) &&
218 		    prio >= curr_prio) {
219 			curr_prio = prio;
220 			ofw_def_impl = ofwp;
221 			return (TRUE);
222 		}
223 	}
224 
225 	return (FALSE);
226 }
227 
228 /* Initializer */
229 int
230 OF_init(void *cookie)
231 {
232 	phandle_t chosen;
233 	int rv;
234 
235 	if (ofw_def_impl == NULL)
236 		return (-1);
237 
238 	ofw_obj = &ofw_kernel_obj;
239 	/*
240 	 * Take care of compiling the selected class, and
241 	 * then statically initialize the OFW object.
242 	 */
243 	kobj_class_compile_static(ofw_def_impl, &ofw_kernel_kops);
244 	kobj_init_static((kobj_t)ofw_obj, ofw_def_impl);
245 
246 	rv = OFW_INIT(ofw_obj, cookie);
247 
248 	if ((chosen = OF_finddevice("/chosen")) != -1)
249 		if (OF_getencprop(chosen, "stdout", &stdout,
250 		    sizeof(stdout)) == -1)
251 			stdout = -1;
252 
253 	return (rv);
254 }
255 
256 static void
257 OF_putchar(int c, void *arg __unused)
258 {
259 	char cbuf;
260 
261 	if (c == '\n') {
262 		cbuf = '\r';
263 		OF_write(stdout, &cbuf, 1);
264 	}
265 
266 	cbuf = c;
267 	OF_write(stdout, &cbuf, 1);
268 }
269 
270 void
271 OF_printf(const char *fmt, ...)
272 {
273 	va_list	va;
274 
275 	va_start(va, fmt);
276 	(void)kvprintf(fmt, OF_putchar, NULL, 10, va);
277 	va_end(va);
278 }
279 
280 /*
281  * Generic functions
282  */
283 
284 /* Test to see if a service exists. */
285 int
286 OF_test(const char *name)
287 {
288 
289 	if (ofw_def_impl == NULL)
290 		return (-1);
291 
292 	return (OFW_TEST(ofw_obj, name));
293 }
294 
295 int
296 OF_interpret(const char *cmd, int nreturns, ...)
297 {
298 	va_list ap;
299 	cell_t slots[16];
300 	int i = 0;
301 	int status;
302 
303 	if (ofw_def_impl == NULL)
304 		return (-1);
305 
306 	status = OFW_INTERPRET(ofw_obj, cmd, nreturns, slots);
307 	if (status == -1)
308 		return (status);
309 
310 	va_start(ap, nreturns);
311 	while (i < nreturns)
312 		*va_arg(ap, cell_t *) = slots[i++];
313 	va_end(ap);
314 
315 	return (status);
316 }
317 
318 /*
319  * Device tree functions
320  */
321 
322 /* Return the next sibling of this node or 0. */
323 phandle_t
324 OF_peer(phandle_t node)
325 {
326 
327 	if (ofw_def_impl == NULL)
328 		return (0);
329 
330 	return (OFW_PEER(ofw_obj, node));
331 }
332 
333 /* Return the first child of this node or 0. */
334 phandle_t
335 OF_child(phandle_t node)
336 {
337 
338 	if (ofw_def_impl == NULL)
339 		return (0);
340 
341 	return (OFW_CHILD(ofw_obj, node));
342 }
343 
344 /* Return the parent of this node or 0. */
345 phandle_t
346 OF_parent(phandle_t node)
347 {
348 
349 	if (ofw_def_impl == NULL)
350 		return (0);
351 
352 	return (OFW_PARENT(ofw_obj, node));
353 }
354 
355 /* Return the package handle that corresponds to an instance handle. */
356 phandle_t
357 OF_instance_to_package(ihandle_t instance)
358 {
359 
360 	if (ofw_def_impl == NULL)
361 		return (-1);
362 
363 	return (OFW_INSTANCE_TO_PACKAGE(ofw_obj, instance));
364 }
365 
366 /* Get the length of a property of a package. */
367 ssize_t
368 OF_getproplen(phandle_t package, const char *propname)
369 {
370 
371 	if (ofw_def_impl == NULL)
372 		return (-1);
373 
374 	return (OFW_GETPROPLEN(ofw_obj, package, propname));
375 }
376 
377 /* Check existence of a property of a package. */
378 int
379 OF_hasprop(phandle_t package, const char *propname)
380 {
381 
382 	return (OF_getproplen(package, propname) >= 0 ? 1 : 0);
383 }
384 
385 /* Get the value of a property of a package. */
386 ssize_t
387 OF_getprop(phandle_t package, const char *propname, void *buf, size_t buflen)
388 {
389 
390 	if (ofw_def_impl == NULL)
391 		return (-1);
392 
393 	return (OFW_GETPROP(ofw_obj, package, propname, buf, buflen));
394 }
395 
396 ssize_t
397 OF_getencprop(phandle_t node, const char *propname, pcell_t *buf, size_t len)
398 {
399 	ssize_t retval;
400 	int i;
401 
402 	KASSERT(len % 4 == 0, ("Need a multiple of 4 bytes"));
403 
404 	retval = OF_getprop(node, propname, buf, len);
405 	if (retval <= 0)
406 		return (retval);
407 
408 	for (i = 0; i < len/4; i++)
409 		buf[i] = be32toh(buf[i]);
410 
411 	return (retval);
412 }
413 
414 /*
415  * Recursively search the node and its parent for the given property, working
416  * downward from the node to the device tree root.  Returns the value of the
417  * first match.
418  */
419 ssize_t
420 OF_searchprop(phandle_t node, const char *propname, void *buf, size_t len)
421 {
422 	ssize_t rv;
423 
424 	for (; node != 0; node = OF_parent(node))
425 		if ((rv = OF_getprop(node, propname, buf, len)) != -1)
426 			return (rv);
427 	return (-1);
428 }
429 
430 ssize_t
431 OF_searchencprop(phandle_t node, const char *propname, pcell_t *buf, size_t len)
432 {
433 	ssize_t rv;
434 
435 	for (; node != 0; node = OF_parent(node))
436 		if ((rv = OF_getencprop(node, propname, buf, len)) != -1)
437 			return (rv);
438 	return (-1);
439 }
440 
441 /*
442  * Store the value of a property of a package into newly allocated memory
443  * (using the M_OFWPROP malloc pool and M_WAITOK).
444  */
445 ssize_t
446 OF_getprop_alloc(phandle_t package, const char *propname, void **buf)
447 {
448 	int len;
449 
450 	*buf = NULL;
451 	if ((len = OF_getproplen(package, propname)) == -1)
452 		return (-1);
453 
454 	if (len > 0) {
455 		*buf = malloc(len, M_OFWPROP, M_WAITOK);
456 		if (OF_getprop(package, propname, *buf, len) == -1) {
457 			free(*buf, M_OFWPROP);
458 			*buf = NULL;
459 			return (-1);
460 		}
461 	}
462 	return (len);
463 }
464 
465 /*
466  * Store the value of a property of a package into newly allocated memory
467  * (using the M_OFWPROP malloc pool and M_WAITOK).  elsz is the size of a
468  * single element, the number of elements is return in number.
469  */
470 ssize_t
471 OF_getprop_alloc_multi(phandle_t package, const char *propname, int elsz, void **buf)
472 {
473 	int len;
474 
475 	*buf = NULL;
476 	if ((len = OF_getproplen(package, propname)) == -1 ||
477 	    len % elsz != 0)
478 		return (-1);
479 
480 	if (len > 0) {
481 		*buf = malloc(len, M_OFWPROP, M_WAITOK);
482 		if (OF_getprop(package, propname, *buf, len) == -1) {
483 			free(*buf, M_OFWPROP);
484 			*buf = NULL;
485 			return (-1);
486 		}
487 	}
488 	return (len / elsz);
489 }
490 
491 ssize_t
492 OF_getencprop_alloc(phandle_t package, const char *name, void **buf)
493 {
494 	ssize_t ret;
495 
496 	ret = OF_getencprop_alloc_multi(package, name, sizeof(pcell_t),
497 	    buf);
498 	if (ret < 0)
499 		return (ret);
500 	else
501 		return (ret * sizeof(pcell_t));
502 }
503 
504 ssize_t
505 OF_getencprop_alloc_multi(phandle_t package, const char *name, int elsz,
506     void **buf)
507 {
508 	ssize_t retval;
509 	pcell_t *cell;
510 	int i;
511 
512 	retval = OF_getprop_alloc_multi(package, name, elsz, buf);
513 	if (retval == -1)
514 		return (-1);
515 
516 	cell = *buf;
517 	for (i = 0; i < retval * elsz / 4; i++)
518 		cell[i] = be32toh(cell[i]);
519 
520 	return (retval);
521 }
522 
523 /* Free buffer allocated by OF_getencprop_alloc or OF_getprop_alloc */
524 void OF_prop_free(void *buf)
525 {
526 
527 	free(buf, M_OFWPROP);
528 }
529 
530 /* Get the next property of a package. */
531 int
532 OF_nextprop(phandle_t package, const char *previous, char *buf, size_t size)
533 {
534 
535 	if (ofw_def_impl == NULL)
536 		return (-1);
537 
538 	return (OFW_NEXTPROP(ofw_obj, package, previous, buf, size));
539 }
540 
541 /* Set the value of a property of a package. */
542 int
543 OF_setprop(phandle_t package, const char *propname, const void *buf, size_t len)
544 {
545 
546 	if (ofw_def_impl == NULL)
547 		return (-1);
548 
549 	return (OFW_SETPROP(ofw_obj, package, propname, buf,len));
550 }
551 
552 /* Convert a device specifier to a fully qualified pathname. */
553 ssize_t
554 OF_canon(const char *device, char *buf, size_t len)
555 {
556 
557 	if (ofw_def_impl == NULL)
558 		return (-1);
559 
560 	return (OFW_CANON(ofw_obj, device, buf, len));
561 }
562 
563 /* Return a package handle for the specified device. */
564 phandle_t
565 OF_finddevice(const char *device)
566 {
567 
568 	if (ofw_def_impl == NULL)
569 		return (-1);
570 
571 	return (OFW_FINDDEVICE(ofw_obj, device));
572 }
573 
574 /* Return the fully qualified pathname corresponding to an instance. */
575 ssize_t
576 OF_instance_to_path(ihandle_t instance, char *buf, size_t len)
577 {
578 
579 	if (ofw_def_impl == NULL)
580 		return (-1);
581 
582 	return (OFW_INSTANCE_TO_PATH(ofw_obj, instance, buf, len));
583 }
584 
585 /* Return the fully qualified pathname corresponding to a package. */
586 ssize_t
587 OF_package_to_path(phandle_t package, char *buf, size_t len)
588 {
589 
590 	if (ofw_def_impl == NULL)
591 		return (-1);
592 
593 	return (OFW_PACKAGE_TO_PATH(ofw_obj, package, buf, len));
594 }
595 
596 /* Look up effective phandle (see FDT/PAPR spec) */
597 static phandle_t
598 OF_child_xref_phandle(phandle_t parent, phandle_t xref)
599 {
600 	phandle_t child, rxref;
601 
602 	/*
603 	 * Recursively descend from parent, looking for a node with a property
604 	 * named either "phandle", "ibm,phandle", or "linux,phandle" that
605 	 * matches the xref we are looking for.
606 	 */
607 
608 	for (child = OF_child(parent); child != 0; child = OF_peer(child)) {
609 		rxref = OF_child_xref_phandle(child, xref);
610 		if (rxref != -1)
611 			return (rxref);
612 
613 		if (OF_getencprop(child, "phandle", &rxref, sizeof(rxref)) ==
614 		    -1 && OF_getencprop(child, "ibm,phandle", &rxref,
615 		    sizeof(rxref)) == -1 && OF_getencprop(child,
616 		    "linux,phandle", &rxref, sizeof(rxref)) == -1)
617 			continue;
618 
619 		if (rxref == xref)
620 			return (child);
621 	}
622 
623 	return (-1);
624 }
625 
626 phandle_t
627 OF_node_from_xref(phandle_t xref)
628 {
629 	struct xrefinfo *xi;
630 	phandle_t node;
631 
632 	if (xref_init_done) {
633 		if ((xi = xrefinfo_find(xref, FIND_BY_XREF)) == NULL)
634 			return (xref);
635 		return (xi->node);
636 	}
637 
638 	if ((node = OF_child_xref_phandle(OF_peer(0), xref)) == -1)
639 		return (xref);
640 	return (node);
641 }
642 
643 phandle_t
644 OF_xref_from_node(phandle_t node)
645 {
646 	struct xrefinfo *xi;
647 	phandle_t xref;
648 
649 	if (xref_init_done) {
650 		if ((xi = xrefinfo_find(node, FIND_BY_NODE)) == NULL)
651 			return (node);
652 		return (xi->xref);
653 	}
654 
655 	if (OF_getencprop(node, "phandle", &xref, sizeof(xref)) == -1 &&
656 	    OF_getencprop(node, "ibm,phandle", &xref, sizeof(xref)) == -1 &&
657 	    OF_getencprop(node, "linux,phandle", &xref, sizeof(xref)) == -1)
658 		return (node);
659 	return (xref);
660 }
661 
662 device_t
663 OF_device_from_xref(phandle_t xref)
664 {
665 	struct xrefinfo *xi;
666 
667 	if (xref_init_done) {
668 		if ((xi = xrefinfo_find(xref, FIND_BY_XREF)) == NULL)
669 			return (NULL);
670 		return (xi->dev);
671 	}
672 	panic("Attempt to find device before xreflist_init");
673 }
674 
675 phandle_t
676 OF_xref_from_device(device_t dev)
677 {
678 	struct xrefinfo *xi;
679 
680 	if (xref_init_done) {
681 		if ((xi = xrefinfo_find((uintptr_t)dev, FIND_BY_DEV)) == NULL)
682 			return (0);
683 		return (xi->xref);
684 	}
685 	panic("Attempt to find xref before xreflist_init");
686 }
687 
688 int
689 OF_device_register_xref(phandle_t xref, device_t dev)
690 {
691 	struct xrefinfo *xi;
692 
693 	/*
694 	 * If the given xref handle doesn't already exist in the list then we
695 	 * add a list entry.  In theory this can only happen on a system where
696 	 * nodes don't contain phandle properties and xref and node handles are
697 	 * synonymous, so the xref handle is added as the node handle as well.
698 	 */
699 	if (xref_init_done) {
700 		if ((xi = xrefinfo_find(xref, FIND_BY_XREF)) == NULL)
701 			xrefinfo_add(xref, xref, dev);
702 		else
703 			xi->dev = dev;
704 		return (0);
705 	}
706 	panic("Attempt to register device before xreflist_init");
707 }
708 
709 /*  Call the method in the scope of a given instance. */
710 int
711 OF_call_method(const char *method, ihandle_t instance, int nargs, int nreturns,
712     ...)
713 {
714 	va_list ap;
715 	cell_t args_n_results[12];
716 	int n, status;
717 
718 	if (nargs > 6 || ofw_def_impl == NULL)
719 		return (-1);
720 	va_start(ap, nreturns);
721 	for (n = 0; n < nargs; n++)
722 		args_n_results[n] = va_arg(ap, cell_t);
723 
724 	status = OFW_CALL_METHOD(ofw_obj, instance, method, nargs, nreturns,
725 	    args_n_results);
726 	if (status != 0)
727 		return (status);
728 
729 	for (; n < nargs + nreturns; n++)
730 		*va_arg(ap, cell_t *) = args_n_results[n];
731 	va_end(ap);
732 	return (0);
733 }
734 
735 /*
736  * Device I/O functions
737  */
738 
739 /* Open an instance for a device. */
740 ihandle_t
741 OF_open(const char *device)
742 {
743 
744 	if (ofw_def_impl == NULL)
745 		return (0);
746 
747 	return (OFW_OPEN(ofw_obj, device));
748 }
749 
750 /* Close an instance. */
751 void
752 OF_close(ihandle_t instance)
753 {
754 
755 	if (ofw_def_impl == NULL)
756 		return;
757 
758 	OFW_CLOSE(ofw_obj, instance);
759 }
760 
761 /* Read from an instance. */
762 ssize_t
763 OF_read(ihandle_t instance, void *addr, size_t len)
764 {
765 
766 	if (ofw_def_impl == NULL)
767 		return (-1);
768 
769 	return (OFW_READ(ofw_obj, instance, addr, len));
770 }
771 
772 /* Write to an instance. */
773 ssize_t
774 OF_write(ihandle_t instance, const void *addr, size_t len)
775 {
776 
777 	if (ofw_def_impl == NULL)
778 		return (-1);
779 
780 	return (OFW_WRITE(ofw_obj, instance, addr, len));
781 }
782 
783 /* Seek to a position. */
784 int
785 OF_seek(ihandle_t instance, uint64_t pos)
786 {
787 
788 	if (ofw_def_impl == NULL)
789 		return (-1);
790 
791 	return (OFW_SEEK(ofw_obj, instance, pos));
792 }
793 
794 /*
795  * Memory functions
796  */
797 
798 /* Claim an area of memory. */
799 void *
800 OF_claim(void *virt, size_t size, u_int align)
801 {
802 
803 	if (ofw_def_impl == NULL)
804 		return ((void *)-1);
805 
806 	return (OFW_CLAIM(ofw_obj, virt, size, align));
807 }
808 
809 /* Release an area of memory. */
810 void
811 OF_release(void *virt, size_t size)
812 {
813 
814 	if (ofw_def_impl == NULL)
815 		return;
816 
817 	OFW_RELEASE(ofw_obj, virt, size);
818 }
819 
820 /*
821  * Control transfer functions
822  */
823 
824 /* Suspend and drop back to the Open Firmware interface. */
825 void
826 OF_enter(void)
827 {
828 
829 	if (ofw_def_impl == NULL)
830 		return;
831 
832 	OFW_ENTER(ofw_obj);
833 }
834 
835 /* Shut down and drop back to the Open Firmware interface. */
836 void
837 OF_exit(void)
838 {
839 
840 	if (ofw_def_impl == NULL)
841 		panic("OF_exit: Open Firmware not available");
842 
843 	/* Should not return */
844 	OFW_EXIT(ofw_obj);
845 
846 	for (;;)			/* just in case */
847 		;
848 }
849