xref: /freebsd/sys/dev/fdt/fdt_common.c (revision 193d9e768ba63fcfb187cfd17f461f7d41345048)
1 /*-
2  * Copyright (c) 2009-2014 The FreeBSD Foundation
3  * All rights reserved.
4  *
5  * This software was developed by Andrew Turner under sponsorship from
6  * the FreeBSD Foundation.
7  * This software was developed by Semihalf under sponsorship from
8  * the FreeBSD Foundation.
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  *
19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  */
31 
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
34 
35 #include <sys/param.h>
36 #include <sys/systm.h>
37 #include <sys/kernel.h>
38 #include <sys/module.h>
39 #include <sys/bus.h>
40 #include <sys/limits.h>
41 #include <sys/sysctl.h>
42 
43 #include <machine/resource.h>
44 
45 #include <dev/fdt/fdt_common.h>
46 #include <dev/ofw/ofw_bus.h>
47 #include <dev/ofw/ofw_bus_subr.h>
48 #include <dev/ofw/openfirm.h>
49 
50 #include "ofw_bus_if.h"
51 
52 #ifdef DEBUG
53 #define debugf(fmt, args...) do { printf("%s(): ", __func__);	\
54     printf(fmt,##args); } while (0)
55 #else
56 #define debugf(fmt, args...)
57 #endif
58 
59 #define FDT_COMPAT_LEN	255
60 #define FDT_TYPE_LEN	64
61 
62 #define FDT_REG_CELLS	4
63 
64 SYSCTL_NODE(_hw, OID_AUTO, fdt, CTLFLAG_RD, 0, "Flattened Device Tree");
65 
66 vm_paddr_t fdt_immr_pa;
67 vm_offset_t fdt_immr_va;
68 vm_offset_t fdt_immr_size;
69 
70 struct fdt_ic_list fdt_ic_list_head = SLIST_HEAD_INITIALIZER(fdt_ic_list_head);
71 
72 static int fdt_is_compatible(phandle_t, const char *);
73 
74 static int
75 fdt_get_range_by_busaddr(phandle_t node, u_long addr, u_long *base,
76     u_long *size)
77 {
78 	pcell_t ranges[32], *rangesptr;
79 	pcell_t addr_cells, size_cells, par_addr_cells;
80 	u_long bus_addr, par_bus_addr, pbase, psize;
81 	int err, i, len, tuple_size, tuples;
82 
83 	if (node == 0) {
84 		*base = 0;
85 		*size = ULONG_MAX;
86 		return (0);
87 	}
88 
89 	if ((fdt_addrsize_cells(node, &addr_cells, &size_cells)) != 0)
90 		return (ENXIO);
91 	/*
92 	 * Process 'ranges' property.
93 	 */
94 	par_addr_cells = fdt_parent_addr_cells(node);
95 	if (par_addr_cells > 2) {
96 		return (ERANGE);
97 	}
98 
99 	len = OF_getproplen(node, "ranges");
100 	if (len < 0)
101 		return (-1);
102 	if (len > sizeof(ranges))
103 		return (ENOMEM);
104 	if (len == 0) {
105 		return (fdt_get_range_by_busaddr(OF_parent(node), addr,
106 		    base, size));
107 	}
108 
109 	if (OF_getprop(node, "ranges", ranges, sizeof(ranges)) <= 0)
110 		return (EINVAL);
111 
112 	tuple_size = addr_cells + par_addr_cells + size_cells;
113 	tuples = len / (tuple_size * sizeof(cell_t));
114 
115 	if (par_addr_cells > 2 || addr_cells > 2 || size_cells > 2)
116 		return (ERANGE);
117 
118 	*base = 0;
119 	*size = 0;
120 
121 	for (i = 0; i < tuples; i++) {
122 		rangesptr = &ranges[i * tuple_size];
123 
124 		bus_addr = fdt_data_get((void *)rangesptr, addr_cells);
125 		if (bus_addr != addr)
126 			continue;
127 		rangesptr += addr_cells;
128 
129 		par_bus_addr = fdt_data_get((void *)rangesptr, par_addr_cells);
130 		rangesptr += par_addr_cells;
131 
132 		err = fdt_get_range_by_busaddr(OF_parent(node), par_bus_addr,
133 		    &pbase, &psize);
134 		if (err > 0)
135 			return (err);
136 		if (err == 0)
137 			*base = pbase;
138 		else
139 			*base = par_bus_addr;
140 
141 		*size = fdt_data_get((void *)rangesptr, size_cells);
142 
143 		return (0);
144 	}
145 
146 	return (EINVAL);
147 }
148 
149 int
150 fdt_get_range(phandle_t node, int range_id, u_long *base, u_long *size)
151 {
152 	pcell_t ranges[6], *rangesptr;
153 	pcell_t addr_cells, size_cells, par_addr_cells;
154 	u_long par_bus_addr, pbase, psize;
155 	int err, len, tuple_size, tuples;
156 
157 	if ((fdt_addrsize_cells(node, &addr_cells, &size_cells)) != 0)
158 		return (ENXIO);
159 	/*
160 	 * Process 'ranges' property.
161 	 */
162 	par_addr_cells = fdt_parent_addr_cells(node);
163 	if (par_addr_cells > 2)
164 		return (ERANGE);
165 
166 	len = OF_getproplen(node, "ranges");
167 	if (len > sizeof(ranges))
168 		return (ENOMEM);
169 	if (len == 0) {
170 		*base = 0;
171 		*size = ULONG_MAX;
172 		return (0);
173 	}
174 
175 	if (!(range_id < len))
176 		return (ERANGE);
177 
178 	if (OF_getprop(node, "ranges", ranges, sizeof(ranges)) <= 0)
179 		return (EINVAL);
180 
181 	tuple_size = sizeof(pcell_t) * (addr_cells + par_addr_cells +
182 	    size_cells);
183 	tuples = len / tuple_size;
184 
185 	if (par_addr_cells > 2 || addr_cells > 2 || size_cells > 2)
186 		return (ERANGE);
187 
188 	*base = 0;
189 	*size = 0;
190 	rangesptr = &ranges[range_id];
191 
192 	*base = fdt_data_get((void *)rangesptr, addr_cells);
193 	rangesptr += addr_cells;
194 
195 	par_bus_addr = fdt_data_get((void *)rangesptr, par_addr_cells);
196 	rangesptr += par_addr_cells;
197 
198 	err = fdt_get_range_by_busaddr(OF_parent(node), par_bus_addr,
199 	   &pbase, &psize);
200 	if (err == 0)
201 		*base += pbase;
202 	else
203 		*base += par_bus_addr;
204 
205 	*size = fdt_data_get((void *)rangesptr, size_cells);
206 	return (0);
207 }
208 
209 int
210 fdt_immr_addr(vm_offset_t immr_va)
211 {
212 	phandle_t node;
213 	u_long base, size;
214 	int r;
215 
216 	/*
217 	 * Try to access the SOC node directly i.e. through /aliases/.
218 	 */
219 	if ((node = OF_finddevice("soc")) != 0)
220 		if (fdt_is_compatible(node, "simple-bus"))
221 			goto moveon;
222 	/*
223 	 * Find the node the long way.
224 	 */
225 	if ((node = OF_finddevice("/")) == 0)
226 		return (ENXIO);
227 
228 	if ((node = fdt_find_compatible(node, "simple-bus", 0)) == 0)
229 		return (ENXIO);
230 
231 moveon:
232 	if ((r = fdt_get_range(node, 0, &base, &size)) == 0) {
233 		fdt_immr_pa = base;
234 		fdt_immr_va = immr_va;
235 		fdt_immr_size = size;
236 	}
237 
238 	return (r);
239 }
240 
241 /*
242  * This routine is an early-usage version of the ofw_bus_is_compatible() when
243  * the ofw_bus I/F is not available (like early console routines and similar).
244  * Note the buffer has to be on the stack since malloc() is usually not
245  * available in such cases either.
246  */
247 static int
248 fdt_is_compatible(phandle_t node, const char *compatstr)
249 {
250 	char buf[FDT_COMPAT_LEN];
251 	char *compat;
252 	int len, onelen, l, rv;
253 
254 	if ((len = OF_getproplen(node, "compatible")) <= 0)
255 		return (0);
256 
257 	compat = (char *)&buf;
258 	bzero(compat, FDT_COMPAT_LEN);
259 
260 	if (OF_getprop(node, "compatible", compat, FDT_COMPAT_LEN) < 0)
261 		return (0);
262 
263 	onelen = strlen(compatstr);
264 	rv = 0;
265 	while (len > 0) {
266 		if (strncasecmp(compat, compatstr, onelen) == 0) {
267 			/* Found it. */
268 			rv = 1;
269 			break;
270 		}
271 		/* Slide to the next sub-string. */
272 		l = strlen(compat) + 1;
273 		compat += l;
274 		len -= l;
275 	}
276 
277 	return (rv);
278 }
279 
280 int
281 fdt_is_compatible_strict(phandle_t node, const char *compatible)
282 {
283 	char compat[FDT_COMPAT_LEN];
284 
285 	if (OF_getproplen(node, "compatible") <= 0)
286 		return (0);
287 
288 	if (OF_getprop(node, "compatible", compat, FDT_COMPAT_LEN) < 0)
289 		return (0);
290 
291 	if (strncasecmp(compat, compatible, FDT_COMPAT_LEN) == 0)
292 		/* This fits. */
293 		return (1);
294 
295 	return (0);
296 }
297 
298 phandle_t
299 fdt_find_compatible(phandle_t start, const char *compat, int strict)
300 {
301 	phandle_t child;
302 
303 	/*
304 	 * Traverse all children of 'start' node, and find first with
305 	 * matching 'compatible' property.
306 	 */
307 	for (child = OF_child(start); child != 0; child = OF_peer(child))
308 		if (fdt_is_compatible(child, compat)) {
309 			if (strict)
310 				if (!fdt_is_compatible_strict(child, compat))
311 					continue;
312 			return (child);
313 		}
314 	return (0);
315 }
316 
317 phandle_t
318 fdt_depth_search_compatible(phandle_t start, const char *compat, int strict)
319 {
320 	phandle_t child, node;
321 
322 	/*
323 	 * Depth-search all descendants of 'start' node, and find first with
324 	 * matching 'compatible' property.
325 	 */
326 	for (node = OF_child(start); node != 0; node = OF_peer(node)) {
327 		if (fdt_is_compatible(node, compat) &&
328 		    (strict == 0 || fdt_is_compatible_strict(node, compat))) {
329 			return (node);
330 		}
331 		child = fdt_depth_search_compatible(node, compat, strict);
332 		if (child != 0)
333 			return (child);
334 	}
335 	return (0);
336 }
337 
338 int
339 fdt_is_enabled(phandle_t node)
340 {
341 	char *stat;
342 	int ena, len;
343 
344 	len = OF_getprop_alloc(node, "status", sizeof(char),
345 	    (void **)&stat);
346 
347 	if (len <= 0)
348 		/* It is OK if no 'status' property. */
349 		return (1);
350 
351 	/* Anything other than 'okay' means disabled. */
352 	ena = 0;
353 	if (strncmp((char *)stat, "okay", len) == 0)
354 		ena = 1;
355 
356 	OF_prop_free(stat);
357 	return (ena);
358 }
359 
360 int
361 fdt_is_type(phandle_t node, const char *typestr)
362 {
363 	char type[FDT_TYPE_LEN];
364 
365 	if (OF_getproplen(node, "device_type") <= 0)
366 		return (0);
367 
368 	if (OF_getprop(node, "device_type", type, FDT_TYPE_LEN) < 0)
369 		return (0);
370 
371 	if (strncasecmp(type, typestr, FDT_TYPE_LEN) == 0)
372 		/* This fits. */
373 		return (1);
374 
375 	return (0);
376 }
377 
378 int
379 fdt_parent_addr_cells(phandle_t node)
380 {
381 	pcell_t addr_cells;
382 
383 	/* Find out #address-cells of the superior bus. */
384 	if (OF_searchprop(OF_parent(node), "#address-cells", &addr_cells,
385 	    sizeof(addr_cells)) <= 0)
386 		return (2);
387 
388 	return ((int)fdt32_to_cpu(addr_cells));
389 }
390 
391 int
392 fdt_pm_is_enabled(phandle_t node)
393 {
394 	int ret;
395 
396 	ret = 1;
397 
398 #if defined(SOC_MV_KIRKWOOD) || defined(SOC_MV_DISCOVERY)
399 	ret = fdt_pm(node);
400 #endif
401 	return (ret);
402 }
403 
404 u_long
405 fdt_data_get(void *data, int cells)
406 {
407 
408 	if (cells == 1)
409 		return (fdt32_to_cpu(*((uint32_t *)data)));
410 
411 	return (fdt64_to_cpu(*((uint64_t *)data)));
412 }
413 
414 int
415 fdt_addrsize_cells(phandle_t node, int *addr_cells, int *size_cells)
416 {
417 	pcell_t cell;
418 	int cell_size;
419 
420 	/*
421 	 * Retrieve #{address,size}-cells.
422 	 */
423 	cell_size = sizeof(cell);
424 	if (OF_getencprop(node, "#address-cells", &cell, cell_size) < cell_size)
425 		*addr_cells = 2;
426 	*addr_cells = (int)cell;
427 
428 	if (OF_getencprop(node, "#size-cells", &cell, cell_size) < cell_size)
429 		cell = 1;
430 	*size_cells = (int)cell;
431 
432 	if (*addr_cells > 3 || *size_cells > 2)
433 		return (ERANGE);
434 	return (0);
435 }
436 
437 int
438 fdt_data_to_res(pcell_t *data, int addr_cells, int size_cells, u_long *start,
439     u_long *count)
440 {
441 
442 	/* Address portion. */
443 	if (addr_cells > 2)
444 		return (ERANGE);
445 
446 	*start = fdt_data_get((void *)data, addr_cells);
447 	data += addr_cells;
448 
449 	/* Size portion. */
450 	if (size_cells > 2)
451 		return (ERANGE);
452 
453 	*count = fdt_data_get((void *)data, size_cells);
454 	return (0);
455 }
456 
457 int
458 fdt_regsize(phandle_t node, u_long *base, u_long *size)
459 {
460 	pcell_t reg[4];
461 	int addr_cells, len, size_cells;
462 
463 	if (fdt_addrsize_cells(OF_parent(node), &addr_cells, &size_cells))
464 		return (ENXIO);
465 
466 	if ((sizeof(pcell_t) * (addr_cells + size_cells)) > sizeof(reg))
467 		return (ENOMEM);
468 
469 	len = OF_getprop(node, "reg", &reg, sizeof(reg));
470 	if (len <= 0)
471 		return (EINVAL);
472 
473 	*base = fdt_data_get(&reg[0], addr_cells);
474 	*size = fdt_data_get(&reg[addr_cells], size_cells);
475 	return (0);
476 }
477 
478 int
479 fdt_reg_to_rl(phandle_t node, struct resource_list *rl)
480 {
481 	u_long end, count, start;
482 	pcell_t *reg, *regptr;
483 	pcell_t addr_cells, size_cells;
484 	int tuple_size, tuples;
485 	int i, rv;
486 	long busaddr, bussize;
487 
488 	if (fdt_addrsize_cells(OF_parent(node), &addr_cells, &size_cells) != 0)
489 		return (ENXIO);
490 	if (fdt_get_range(OF_parent(node), 0, &busaddr, &bussize)) {
491 		busaddr = 0;
492 		bussize = 0;
493 	}
494 
495 	tuple_size = sizeof(pcell_t) * (addr_cells + size_cells);
496 	tuples = OF_getprop_alloc(node, "reg", tuple_size, (void **)&reg);
497 	debugf("addr_cells = %d, size_cells = %d\n", addr_cells, size_cells);
498 	debugf("tuples = %d, tuple size = %d\n", tuples, tuple_size);
499 	if (tuples <= 0)
500 		/* No 'reg' property in this node. */
501 		return (0);
502 
503 	regptr = reg;
504 	for (i = 0; i < tuples; i++) {
505 
506 		rv = fdt_data_to_res(reg, addr_cells, size_cells, &start,
507 		    &count);
508 		if (rv != 0) {
509 			resource_list_free(rl);
510 			goto out;
511 		}
512 		reg += addr_cells + size_cells;
513 
514 		/* Calculate address range relative to base. */
515 		start += busaddr;
516 		end = start + count - 1;
517 
518 		debugf("reg addr start = %lx, end = %lx, count = %lx\n", start,
519 		    end, count);
520 
521 		resource_list_add(rl, SYS_RES_MEMORY, i, start, end,
522 		    count);
523 	}
524 	rv = 0;
525 
526 out:
527 	OF_prop_free(regptr);
528 	return (rv);
529 }
530 
531 int
532 fdt_get_phyaddr(phandle_t node, device_t dev, int *phy_addr, void **phy_sc)
533 {
534 	phandle_t phy_node;
535 	pcell_t phy_handle, phy_reg;
536 	uint32_t i;
537 	device_t parent, child;
538 
539 	if (OF_getencprop(node, "phy-handle", (void *)&phy_handle,
540 	    sizeof(phy_handle)) <= 0)
541 		return (ENXIO);
542 
543 	phy_node = OF_node_from_xref(phy_handle);
544 
545 	if (OF_getencprop(phy_node, "reg", (void *)&phy_reg,
546 	    sizeof(phy_reg)) <= 0)
547 		return (ENXIO);
548 
549 	*phy_addr = phy_reg;
550 
551 	/*
552 	 * Search for softc used to communicate with phy.
553 	 */
554 
555 	/*
556 	 * Step 1: Search for ancestor of the phy-node with a "phy-handle"
557 	 * property set.
558 	 */
559 	phy_node = OF_parent(phy_node);
560 	while (phy_node != 0) {
561 		if (OF_getprop(phy_node, "phy-handle", (void *)&phy_handle,
562 		    sizeof(phy_handle)) > 0)
563 			break;
564 		phy_node = OF_parent(phy_node);
565 	}
566 	if (phy_node == 0)
567 		return (ENXIO);
568 
569 	/*
570 	 * Step 2: For each device with the same parent and name as ours
571 	 * compare its node with the one found in step 1, ancestor of phy
572 	 * node (stored in phy_node).
573 	 */
574 	parent = device_get_parent(dev);
575 	i = 0;
576 	child = device_find_child(parent, device_get_name(dev), i);
577 	while (child != NULL) {
578 		if (ofw_bus_get_node(child) == phy_node)
579 			break;
580 		i++;
581 		child = device_find_child(parent, device_get_name(dev), i);
582 	}
583 	if (child == NULL)
584 		return (ENXIO);
585 
586 	/*
587 	 * Use softc of the device found.
588 	 */
589 	*phy_sc = (void *)device_get_softc(child);
590 
591 	return (0);
592 }
593 
594 int
595 fdt_get_reserved_regions(struct mem_region *mr, int *mrcnt)
596 {
597 	pcell_t reserve[FDT_REG_CELLS * FDT_MEM_REGIONS];
598 	pcell_t *reservep;
599 	phandle_t memory, root;
600 	uint32_t memory_size;
601 	int addr_cells, size_cells;
602 	int i, max_size, res_len, rv, tuple_size, tuples;
603 
604 	max_size = sizeof(reserve);
605 	root = OF_finddevice("/");
606 	memory = OF_finddevice("/memory");
607 	if (memory == -1) {
608 		rv = ENXIO;
609 		goto out;
610 	}
611 
612 	if ((rv = fdt_addrsize_cells(OF_parent(memory), &addr_cells,
613 	    &size_cells)) != 0)
614 		goto out;
615 
616 	if (addr_cells > 2) {
617 		rv = ERANGE;
618 		goto out;
619 	}
620 
621 	tuple_size = sizeof(pcell_t) * (addr_cells + size_cells);
622 
623 	res_len = OF_getproplen(root, "memreserve");
624 	if (res_len <= 0 || res_len > sizeof(reserve)) {
625 		rv = ERANGE;
626 		goto out;
627 	}
628 
629 	if (OF_getprop(root, "memreserve", reserve, res_len) <= 0) {
630 		rv = ENXIO;
631 		goto out;
632 	}
633 
634 	memory_size = 0;
635 	tuples = res_len / tuple_size;
636 	reservep = (pcell_t *)&reserve;
637 	for (i = 0; i < tuples; i++) {
638 
639 		rv = fdt_data_to_res(reservep, addr_cells, size_cells,
640 			(u_long *)&mr[i].mr_start, (u_long *)&mr[i].mr_size);
641 
642 		if (rv != 0)
643 			goto out;
644 
645 		reservep += addr_cells + size_cells;
646 	}
647 
648 	*mrcnt = i;
649 	rv = 0;
650 out:
651 	return (rv);
652 }
653 
654 int
655 fdt_get_mem_regions(struct mem_region *mr, int *mrcnt, uint64_t *memsize)
656 {
657 	pcell_t reg[FDT_REG_CELLS * FDT_MEM_REGIONS];
658 	pcell_t *regp;
659 	phandle_t memory;
660 	uint64_t memory_size;
661 	int addr_cells, size_cells;
662 	int i, max_size, reg_len, rv, tuple_size, tuples;
663 
664 	max_size = sizeof(reg);
665 	memory = OF_finddevice("/memory");
666 	if (memory == -1) {
667 		rv = ENXIO;
668 		goto out;
669 	}
670 
671 	if ((rv = fdt_addrsize_cells(OF_parent(memory), &addr_cells,
672 	    &size_cells)) != 0)
673 		goto out;
674 
675 	if (addr_cells > 2) {
676 		rv = ERANGE;
677 		goto out;
678 	}
679 
680 	tuple_size = sizeof(pcell_t) * (addr_cells + size_cells);
681 	reg_len = OF_getproplen(memory, "reg");
682 	if (reg_len <= 0 || reg_len > sizeof(reg)) {
683 		rv = ERANGE;
684 		goto out;
685 	}
686 
687 	if (OF_getprop(memory, "reg", reg, reg_len) <= 0) {
688 		rv = ENXIO;
689 		goto out;
690 	}
691 
692 	memory_size = 0;
693 	tuples = reg_len / tuple_size;
694 	regp = (pcell_t *)&reg;
695 	for (i = 0; i < tuples; i++) {
696 
697 		rv = fdt_data_to_res(regp, addr_cells, size_cells,
698 			(u_long *)&mr[i].mr_start, (u_long *)&mr[i].mr_size);
699 
700 		if (rv != 0)
701 			goto out;
702 
703 		regp += addr_cells + size_cells;
704 		memory_size += mr[i].mr_size;
705 	}
706 
707 	if (memory_size == 0) {
708 		rv = ERANGE;
709 		goto out;
710 	}
711 
712 	*mrcnt = i;
713 	if (memsize != NULL)
714 		*memsize = memory_size;
715 	rv = 0;
716 out:
717 	return (rv);
718 }
719 
720 int
721 fdt_get_unit(device_t dev)
722 {
723 	const char * name;
724 
725 	name = ofw_bus_get_name(dev);
726 	name = strchr(name, '@') + 1;
727 
728 	return (strtol(name,NULL,0));
729 }
730 
731 int
732 fdt_get_chosen_bootargs(char *bootargs, size_t max_size)
733 {
734 	phandle_t chosen;
735 
736 	chosen = OF_finddevice("/chosen");
737 	if (chosen == -1)
738 		return (ENXIO);
739 	if (OF_getprop(chosen, "bootargs", bootargs, max_size) == -1)
740 		return (ENXIO);
741 	return (0);
742 }
743