xref: /freebsd/sys/dev/ofw/ofw_standard.c (revision 2b8331622f0b212cf3bb4fc4914a501e5321d506)
1 /*	$NetBSD: Locore.c,v 1.7 2000/08/20 07:04:59 tsubai Exp $	*/
2 
3 /*-
4  * SPDX-License-Identifier: BSD-4-Clause AND BSD-2-Clause-FreeBSD
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 <sys/param.h>
64 #include <sys/kernel.h>
65 #include <sys/malloc.h>
66 #include <sys/systm.h>
67 
68 #include <machine/stdarg.h>
69 
70 #include <dev/ofw/ofwvar.h>
71 #include <dev/ofw/openfirm.h>
72 
73 #include "ofw_if.h"
74 
75 static int ofw_std_init(ofw_t ofw, void *openfirm);
76 static int ofw_std_test(ofw_t ofw, const char *name);
77 static int ofw_std_interpret(ofw_t ofw, const char *cmd, int nreturns,
78     cell_t *returns);
79 static phandle_t ofw_std_peer(ofw_t ofw, phandle_t node);
80 static phandle_t ofw_std_child(ofw_t ofw, phandle_t node);
81 static phandle_t ofw_std_parent(ofw_t ofw, phandle_t node);
82 static phandle_t ofw_std_instance_to_package(ofw_t ofw, ihandle_t instance);
83 static ssize_t ofw_std_getproplen(ofw_t ofw, phandle_t package,
84     const char *propname);
85 static ssize_t ofw_std_getprop(ofw_t ofw, phandle_t package,
86     const char *propname, void *buf, size_t buflen);
87 static int ofw_std_nextprop(ofw_t ofw, phandle_t package, const char *previous,
88     char *buf, size_t);
89 static int ofw_std_setprop(ofw_t ofw, phandle_t package, const char *propname,
90     const void *buf, size_t len);
91 static ssize_t ofw_std_canon(ofw_t ofw, const char *device, char *buf,
92     size_t len);
93 static phandle_t ofw_std_finddevice(ofw_t ofw, const char *device);
94 static ssize_t ofw_std_instance_to_path(ofw_t ofw, ihandle_t instance,
95     char *buf, size_t len);
96 static ssize_t ofw_std_package_to_path(ofw_t ofw, phandle_t package, char *buf,
97     size_t len);
98 static int ofw_std_call_method(ofw_t ofw, ihandle_t instance,
99     const char *method, int nargs, int nreturns, cell_t *args_and_returns);
100 static ihandle_t ofw_std_open(ofw_t ofw, const char *device);
101 static void ofw_std_close(ofw_t ofw, ihandle_t instance);
102 static ssize_t ofw_std_read(ofw_t ofw, ihandle_t instance, void *addr,
103     size_t len);
104 static ssize_t ofw_std_write(ofw_t ofw, ihandle_t instance, const void *addr,
105     size_t len);
106 static int ofw_std_seek(ofw_t ofw, ihandle_t instance, uint64_t pos);
107 static caddr_t ofw_std_claim(ofw_t ofw, void *virt, size_t size, u_int align);
108 static void ofw_std_release(ofw_t ofw, void *virt, size_t size);
109 static void ofw_std_enter(ofw_t ofw);
110 static void ofw_std_exit(ofw_t ofw);
111 
112 static ofw_method_t ofw_std_methods[] = {
113 	OFWMETHOD(ofw_init,			ofw_std_init),
114 	OFWMETHOD(ofw_peer,			ofw_std_peer),
115 	OFWMETHOD(ofw_child,			ofw_std_child),
116 	OFWMETHOD(ofw_parent,			ofw_std_parent),
117 	OFWMETHOD(ofw_instance_to_package,	ofw_std_instance_to_package),
118 	OFWMETHOD(ofw_getproplen,		ofw_std_getproplen),
119 	OFWMETHOD(ofw_getprop,			ofw_std_getprop),
120 	OFWMETHOD(ofw_nextprop,			ofw_std_nextprop),
121 	OFWMETHOD(ofw_setprop,			ofw_std_setprop),
122 	OFWMETHOD(ofw_canon,			ofw_std_canon),
123 	OFWMETHOD(ofw_finddevice,		ofw_std_finddevice),
124 	OFWMETHOD(ofw_instance_to_path,		ofw_std_instance_to_path),
125 	OFWMETHOD(ofw_package_to_path,		ofw_std_package_to_path),
126 
127 	OFWMETHOD(ofw_test,			ofw_std_test),
128 	OFWMETHOD(ofw_call_method,		ofw_std_call_method),
129 	OFWMETHOD(ofw_interpret,		ofw_std_interpret),
130 	OFWMETHOD(ofw_open,			ofw_std_open),
131 	OFWMETHOD(ofw_close,			ofw_std_close),
132 	OFWMETHOD(ofw_read,			ofw_std_read),
133 	OFWMETHOD(ofw_write,			ofw_std_write),
134 	OFWMETHOD(ofw_seek,			ofw_std_seek),
135 	OFWMETHOD(ofw_claim,			ofw_std_claim),
136 	OFWMETHOD(ofw_release,			ofw_std_release),
137 	OFWMETHOD(ofw_enter,			ofw_std_enter),
138 	OFWMETHOD(ofw_exit,			ofw_std_exit),
139 	{ 0, 0 }
140 };
141 
142 static ofw_def_t ofw_std = {
143 	OFW_STD_DIRECT,
144 	ofw_std_methods,
145 	0
146 };
147 OFW_DEF(ofw_std);
148 
149 static int (*openfirmware)(void *);
150 
151 /* Initializer */
152 
153 static int
154 ofw_std_init(ofw_t ofw, void *openfirm)
155 {
156 
157 	openfirmware = (int (*)(void *))openfirm;
158 	return (0);
159 }
160 
161 /*
162  * Generic functions
163  */
164 
165 /* Test to see if a service exists. */
166 static int
167 ofw_std_test(ofw_t ofw, const char *name)
168 {
169 	struct {
170 		cell_t name;
171 		cell_t nargs;
172 		cell_t nreturns;
173 		cell_t service;
174 		cell_t missing;
175 	} args = {
176 		(cell_t)"test",
177 		1,
178 		1,
179 	};
180 
181 	args.service = (cell_t)name;
182 	if (openfirmware(&args) == -1)
183 		return (-1);
184 	return (args.missing);
185 }
186 
187 static int
188 ofw_std_interpret(ofw_t ofw, const char *cmd, int nreturns, cell_t *returns)
189 {
190 	struct {
191 		cell_t name;
192 		cell_t nargs;
193 		cell_t nreturns;
194 		cell_t slot[16];
195 	} args = {
196 		(cell_t)"interpret",
197 		1,
198 	};
199 	cell_t status;
200 	int i = 0, j = 0;
201 
202 	args.nreturns = ++nreturns;
203 	args.slot[i++] = (cell_t)cmd;
204 	if (openfirmware(&args) == -1)
205 		return (-1);
206 	status = args.slot[i++];
207 	while (i < 1 + nreturns)
208 		returns[j++] = args.slot[i++];
209 	return (status);
210 }
211 
212 /*
213  * Device tree functions
214  */
215 
216 /* Return the next sibling of this node or 0. */
217 static phandle_t
218 ofw_std_peer(ofw_t ofw, phandle_t node)
219 {
220 	struct {
221 		cell_t name;
222 		cell_t nargs;
223 		cell_t nreturns;
224 		cell_t node;
225 		cell_t next;
226 	} args = {
227 		(cell_t)"peer",
228 		1,
229 		1,
230 	};
231 
232 	args.node = node;
233 	if (openfirmware(&args) == -1)
234 		return (0);
235 	return (args.next);
236 }
237 
238 /* Return the first child of this node or 0. */
239 static phandle_t
240 ofw_std_child(ofw_t ofw, phandle_t node)
241 {
242 	struct {
243 		cell_t name;
244 		cell_t nargs;
245 		cell_t nreturns;
246 		cell_t node;
247 		cell_t child;
248 	} args = {
249 		(cell_t)"child",
250 		1,
251 		1,
252 	};
253 
254 	args.node = node;
255 	if (openfirmware(&args) == -1)
256 		return (0);
257 	return (args.child);
258 }
259 
260 /* Return the parent of this node or 0. */
261 static phandle_t
262 ofw_std_parent(ofw_t ofw, phandle_t node)
263 {
264 	struct {
265 		cell_t name;
266 		cell_t nargs;
267 		cell_t nreturns;
268 		cell_t node;
269 		cell_t parent;
270 	} args = {
271 		(cell_t)"parent",
272 		1,
273 		1,
274 	};
275 
276 	args.node = node;
277 	if (openfirmware(&args) == -1)
278 		return (0);
279 	return (args.parent);
280 }
281 
282 /* Return the package handle that corresponds to an instance handle. */
283 static phandle_t
284 ofw_std_instance_to_package(ofw_t ofw, ihandle_t instance)
285 {
286 	struct {
287 		cell_t name;
288 		cell_t nargs;
289 		cell_t nreturns;
290 		cell_t instance;
291 		cell_t package;
292 	} args = {
293 		(cell_t)"instance-to-package",
294 		1,
295 		1,
296 	};
297 
298 	args.instance = instance;
299 	if (openfirmware(&args) == -1)
300 		return (-1);
301 	return (args.package);
302 }
303 
304 /* Get the length of a property of a package. */
305 static ssize_t
306 ofw_std_getproplen(ofw_t ofw, phandle_t package, const char *propname)
307 {
308 	struct {
309 		cell_t name;
310 		cell_t nargs;
311 		cell_t nreturns;
312 		cell_t package;
313 		cell_t propname;
314 		cell_t proplen;
315 	} args = {
316 		(cell_t)"getproplen",
317 		2,
318 		1,
319 	};
320 
321 	args.package = package;
322 	args.propname = (cell_t)propname;
323 	if (openfirmware(&args) == -1)
324 		return (-1);
325 	return (args.proplen);
326 }
327 
328 /* Get the value of a property of a package. */
329 static ssize_t
330 ofw_std_getprop(ofw_t ofw, phandle_t package, const char *propname, void *buf,
331     size_t buflen)
332 {
333 	struct {
334 		cell_t name;
335 		cell_t nargs;
336 		cell_t nreturns;
337 		cell_t package;
338 		cell_t propname;
339 		cell_t buf;
340 		cell_t buflen;
341 		cell_t size;
342 	} args = {
343 		(cell_t)"getprop",
344 		4,
345 		1,
346 	};
347 
348 	args.package = package;
349 	args.propname = (cell_t)propname;
350 	args.buf = (cell_t)buf;
351 	args.buflen = buflen;
352 	if (openfirmware(&args) == -1)
353 		return (-1);
354 	return (args.size);
355 }
356 
357 /* Get the next property of a package. */
358 static int
359 ofw_std_nextprop(ofw_t ofw, phandle_t package, const char *previous, char *buf,
360     size_t size)
361 {
362 	struct {
363 		cell_t name;
364 		cell_t nargs;
365 		cell_t nreturns;
366 		cell_t package;
367 		cell_t previous;
368 		cell_t buf;
369 		cell_t flag;
370 	} args = {
371 		(cell_t)"nextprop",
372 		3,
373 		1,
374 	};
375 
376 	args.package = package;
377 	args.previous = (cell_t)previous;
378 	args.buf = (cell_t)buf;
379 	if (openfirmware(&args) == -1)
380 		return (-1);
381 	return (args.flag);
382 }
383 
384 /* Set the value of a property of a package. */
385 /* XXX Has a bug on FirePower */
386 static int
387 ofw_std_setprop(ofw_t ofw, phandle_t package, const char *propname,
388     const void *buf, size_t len)
389 {
390 	struct {
391 		cell_t name;
392 		cell_t nargs;
393 		cell_t nreturns;
394 		cell_t package;
395 		cell_t propname;
396 		cell_t buf;
397 		cell_t len;
398 		cell_t size;
399 	} args = {
400 		(cell_t)"setprop",
401 		4,
402 		1,
403 	};
404 
405 	args.package = package;
406 	args.propname = (cell_t)propname;
407 	args.buf = (cell_t)buf;
408 	args.len = len;
409 	if (openfirmware(&args) == -1)
410 		return (-1);
411 	return (args.size);
412 }
413 
414 /* Convert a device specifier to a fully qualified pathname. */
415 static ssize_t
416 ofw_std_canon(ofw_t ofw, const char *device, char *buf, size_t len)
417 {
418 	struct {
419 		cell_t name;
420 		cell_t nargs;
421 		cell_t nreturns;
422 		cell_t device;
423 		cell_t buf;
424 		cell_t len;
425 		cell_t size;
426 	} args = {
427 		(cell_t)"canon",
428 		3,
429 		1,
430 	};
431 
432 	args.device = (cell_t)device;
433 	args.buf = (cell_t)buf;
434 	args.len = len;
435 	if (openfirmware(&args) == -1)
436 		return (-1);
437 	return (args.size);
438 }
439 
440 /* Return a package handle for the specified device. */
441 static phandle_t
442 ofw_std_finddevice(ofw_t ofw, const char *device)
443 {
444 	struct {
445 		cell_t name;
446 		cell_t nargs;
447 		cell_t nreturns;
448 		cell_t device;
449 		cell_t package;
450 	} args = {
451 		(cell_t)"finddevice",
452 		1,
453 		1,
454 	};
455 
456 	args.device = (cell_t)device;
457 	if (openfirmware(&args) == -1)
458 		return (-1);
459 	return (args.package);
460 }
461 
462 /* Return the fully qualified pathname corresponding to an instance. */
463 static ssize_t
464 ofw_std_instance_to_path(ofw_t ofw, ihandle_t instance, char *buf, size_t len)
465 {
466 	struct {
467 		cell_t name;
468 		cell_t nargs;
469 		cell_t nreturns;
470 		cell_t instance;
471 		cell_t buf;
472 		cell_t len;
473 		cell_t size;
474 	} args = {
475 		(cell_t)"instance-to-path",
476 		3,
477 		1,
478 	};
479 
480 	args.instance = instance;
481 	args.buf = (cell_t)buf;
482 	args.len = len;
483 	if (openfirmware(&args) == -1)
484 		return (-1);
485 	return (args.size);
486 }
487 
488 /* Return the fully qualified pathname corresponding to a package. */
489 static ssize_t
490 ofw_std_package_to_path(ofw_t ofw, phandle_t package, char *buf, size_t len)
491 {
492 	struct {
493 		cell_t name;
494 		cell_t nargs;
495 		cell_t nreturns;
496 		cell_t package;
497 		cell_t buf;
498 		cell_t len;
499 		cell_t size;
500 	} args = {
501 		(cell_t)"package-to-path",
502 		3,
503 		1,
504 	};
505 
506 	args.package = package;
507 	args.buf = (cell_t)buf;
508 	args.len = len;
509 	if (openfirmware(&args) == -1)
510 		return (-1);
511 	return (args.size);
512 }
513 
514 /*  Call the method in the scope of a given instance. */
515 static int
516 ofw_std_call_method(ofw_t ofw, ihandle_t instance, const char *method,
517     int nargs, int nreturns, cell_t *args_and_returns)
518 {
519 	struct {
520 		cell_t name;
521 		cell_t nargs;
522 		cell_t nreturns;
523 		cell_t method;
524 		cell_t instance;
525 		cell_t args_n_results[12];
526 	} args = {
527 		(cell_t)"call-method",
528 		2,
529 		1,
530 	};
531 	cell_t *ap, *cp;
532 	int n;
533 
534 	if (nargs > 6)
535 		return (-1);
536 	args.nargs = nargs + 2;
537 	args.nreturns = nreturns + 1;
538 	args.method = (cell_t)method;
539 	args.instance = instance;
540 
541 	ap = args_and_returns;
542 	for (cp = args.args_n_results + (n = nargs); --n >= 0;)
543 		*--cp = *(ap++);
544 	if (openfirmware(&args) == -1)
545 		return (-1);
546 	if (args.args_n_results[nargs])
547 		return (args.args_n_results[nargs]);
548 	for (cp = args.args_n_results + nargs + (n = args.nreturns); --n > 0;)
549 		*(ap++) = *--cp;
550 	return (0);
551 }
552 
553 /*
554  * Device I/O functions
555  */
556 
557 /* Open an instance for a device. */
558 static ihandle_t
559 ofw_std_open(ofw_t ofw, const char *device)
560 {
561 	struct {
562 		cell_t name;
563 		cell_t nargs;
564 		cell_t nreturns;
565 		cell_t device;
566 		cell_t instance;
567 	} args = {
568 		(cell_t)"open",
569 		1,
570 		1,
571 	};
572 
573 	args.device = (cell_t)device;
574 	if (openfirmware(&args) == -1 || args.instance == 0)
575 		return (-1);
576 	return (args.instance);
577 }
578 
579 /* Close an instance. */
580 static void
581 ofw_std_close(ofw_t ofw, ihandle_t instance)
582 {
583 	struct {
584 		cell_t name;
585 		cell_t nargs;
586 		cell_t nreturns;
587 		cell_t instance;
588 	} args = {
589 		(cell_t)"close",
590 		1,
591 		0,
592 	};
593 
594 	args.instance = instance;
595 	openfirmware(&args);
596 }
597 
598 /* Read from an instance. */
599 static ssize_t
600 ofw_std_read(ofw_t ofw, ihandle_t instance, void *addr, size_t len)
601 {
602 	struct {
603 		cell_t name;
604 		cell_t nargs;
605 		cell_t nreturns;
606 		cell_t instance;
607 		cell_t addr;
608 		cell_t len;
609 		cell_t actual;
610 	} args = {
611 		(cell_t)"read",
612 		3,
613 		1,
614 	};
615 
616 	args.instance = instance;
617 	args.addr = (cell_t)addr;
618 	args.len = len;
619 	if (openfirmware(&args) == -1)
620 		return (-1);
621 
622 	return (args.actual);
623 }
624 
625 /* Write to an instance. */
626 static ssize_t
627 ofw_std_write(ofw_t ofw, ihandle_t instance, const void *addr, size_t len)
628 {
629 	struct {
630 		cell_t name;
631 		cell_t nargs;
632 		cell_t nreturns;
633 		cell_t instance;
634 		cell_t addr;
635 		cell_t len;
636 		cell_t actual;
637 	} args = {
638 		(cell_t)"write",
639 		3,
640 		1,
641 	};
642 
643 	args.instance = instance;
644 	args.addr = (cell_t)addr;
645 	args.len = len;
646 	if (openfirmware(&args) == -1)
647 		return (-1);
648 	return (args.actual);
649 }
650 
651 /* Seek to a position. */
652 static int
653 ofw_std_seek(ofw_t ofw, ihandle_t instance, uint64_t pos)
654 {
655 	struct {
656 		cell_t name;
657 		cell_t nargs;
658 		cell_t nreturns;
659 		cell_t instance;
660 		cell_t poshi;
661 		cell_t poslo;
662 		cell_t status;
663 	} args = {
664 		(cell_t)"seek",
665 		3,
666 		1,
667 	};
668 
669 	args.instance = instance;
670 	args.poshi = pos >> 32;
671 	args.poslo = pos;
672 	if (openfirmware(&args) == -1)
673 		return (-1);
674 	return (args.status);
675 }
676 
677 /*
678  * Memory functions
679  */
680 
681 /* Claim an area of memory. */
682 static caddr_t
683 ofw_std_claim(ofw_t ofw, void *virt, size_t size, u_int align)
684 {
685 	struct {
686 		cell_t name;
687 		cell_t nargs;
688 		cell_t nreturns;
689 		cell_t virt;
690 		cell_t size;
691 		cell_t align;
692 		cell_t baseaddr;
693 	} args = {
694 		(cell_t)"claim",
695 		3,
696 		1,
697 	};
698 
699 	args.virt = (cell_t)virt;
700 	args.size = size;
701 	args.align = align;
702 	if (openfirmware(&args) == -1)
703 		return ((void *)-1);
704 	return ((void *)args.baseaddr);
705 }
706 
707 /* Release an area of memory. */
708 static void
709 ofw_std_release(ofw_t ofw, void *virt, size_t size)
710 {
711 	struct {
712 		cell_t name;
713 		cell_t nargs;
714 		cell_t nreturns;
715 		cell_t virt;
716 		cell_t size;
717 	} args = {
718 		(cell_t)"release",
719 		2,
720 		0,
721 	};
722 
723 	args.virt = (cell_t)virt;
724 	args.size = size;
725 	openfirmware(&args);
726 }
727 
728 /*
729  * Control transfer functions
730  */
731 
732 /* Suspend and drop back to the Open Firmware interface. */
733 static void
734 ofw_std_enter(ofw_t ofw)
735 {
736 	struct {
737 		cell_t name;
738 		cell_t nargs;
739 		cell_t nreturns;
740 	} args = {
741 		(cell_t)"enter",
742 		0,
743 		0,
744 	};
745 
746 	openfirmware(&args);
747 	/* We may come back. */
748 }
749 
750 /* Shut down and drop back to the Open Firmware interface. */
751 static void
752 ofw_std_exit(ofw_t ofw)
753 {
754 	struct {
755 		cell_t name;
756 		cell_t nargs;
757 		cell_t nreturns;
758 	} args = {
759 		(cell_t)"exit",
760 		0,
761 		0,
762 	};
763 
764 	openfirmware(&args);
765 	for (;;)			/* just in case */
766 		;
767 }
768