X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=arch%2Fpowerpc%2Fboot%2Fflatdevtree.c;fp=arch%2Fpowerpc%2Fboot%2Fflatdevtree.c;h=c76c194715b211056c3c6d658d1538bd0904c505;hb=76828883507a47dae78837ab5dec5a5b4513c667;hp=0000000000000000000000000000000000000000;hpb=64ba3f394c830ec48a1c31b53dcae312c56f1604;p=linux-2.6.git

diff --git a/arch/powerpc/boot/flatdevtree.c b/arch/powerpc/boot/flatdevtree.c
new file mode 100644
index 000000000..c76c19471
--- /dev/null
+++ b/arch/powerpc/boot/flatdevtree.c
@@ -0,0 +1,880 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ * Copyright Pantelis Antoniou 2006
+ * Copyright (C) IBM Corporation 2006
+ *
+ * Authors: Pantelis Antoniou <pantelis@embeddedalley.com>
+ *	    Hollis Blanchard <hollisb@us.ibm.com>
+ *	    Mark A. Greer <mgreer@mvista.com>
+ *	    Paul Mackerras <paulus@samba.org>
+ */
+
+#include <string.h>
+#include <stddef.h>
+#include "flatdevtree.h"
+#include "flatdevtree_env.h"
+
+#define _ALIGN(x, al)	(((x) + (al) - 1) & ~((al) - 1))
+
+/* Routines for keeping node ptrs returned by ft_find_device current */
+/* First entry not used b/c it would return 0 and be taken as NULL/error */
+static void *ft_node_add(struct ft_cxt *cxt, char *node)
+{
+	unsigned int i;
+
+	for (i = 1; i < cxt->nodes_used; i++)	/* already there? */
+		if (cxt->node_tbl[i] == node)
+			return (void *)i;
+
+	if (cxt->nodes_used < cxt->node_max) {
+		cxt->node_tbl[cxt->nodes_used] = node;
+		return (void *)cxt->nodes_used++;
+	}
+
+	return NULL;
+}
+
+static char *ft_node_ph2node(struct ft_cxt *cxt, const void *phandle)
+{
+	unsigned int i = (unsigned int)phandle;
+
+	if (i < cxt->nodes_used)
+		return cxt->node_tbl[i];
+	return NULL;
+}
+
+static void ft_node_update_before(struct ft_cxt *cxt, char *addr, int shift)
+{
+	unsigned int i;
+
+	if (shift == 0)
+		return;
+
+	for (i = 1; i < cxt->nodes_used; i++)
+		if (cxt->node_tbl[i] < addr)
+			cxt->node_tbl[i] += shift;
+}
+
+static void ft_node_update_after(struct ft_cxt *cxt, char *addr, int shift)
+{
+	unsigned int i;
+
+	if (shift == 0)
+		return;
+
+	for (i = 1; i < cxt->nodes_used; i++)
+		if (cxt->node_tbl[i] >= addr)
+			cxt->node_tbl[i] += shift;
+}
+
+/* Struct used to return info from ft_next() */
+struct ft_atom {
+	u32 tag;
+	const char *name;
+	void *data;
+	u32 size;
+};
+
+/* Set ptrs to current one's info; return addr of next one */
+static char *ft_next(struct ft_cxt *cxt, char *p, struct ft_atom *ret)
+{
+	u32 sz;
+
+	if (p >= cxt->rgn[FT_STRUCT].start + cxt->rgn[FT_STRUCT].size)
+		return NULL;
+
+	ret->tag = be32_to_cpu(*(u32 *) p);
+	p += 4;
+
+	switch (ret->tag) {	/* Tag */
+	case OF_DT_BEGIN_NODE:
+		ret->name = p;
+		ret->data = (void *)(p - 4);	/* start of node */
+		p += _ALIGN(strlen(p) + 1, 4);
+		break;
+	case OF_DT_PROP:
+		ret->size = sz = be32_to_cpu(*(u32 *) p);
+		ret->name = cxt->str_anchor + be32_to_cpu(*(u32 *) (p + 4));
+		ret->data = (void *)(p + 8);
+		p += 8 + _ALIGN(sz, 4);
+		break;
+	case OF_DT_END_NODE:
+	case OF_DT_NOP:
+		break;
+	case OF_DT_END:
+	default:
+		p = NULL;
+		break;
+	}
+
+	return p;
+}
+
+#define HDR_SIZE	_ALIGN(sizeof(struct boot_param_header), 8)
+#define EXPAND_INCR	1024	/* alloc this much extra when expanding */
+
+/* See if the regions are in the standard order and non-overlapping */
+static int ft_ordered(struct ft_cxt *cxt)
+{
+	char *p = (char *)cxt->bph + HDR_SIZE;
+	enum ft_rgn_id r;
+
+	for (r = FT_RSVMAP; r <= FT_STRINGS; ++r) {
+		if (p > cxt->rgn[r].start)
+			return 0;
+		p = cxt->rgn[r].start + cxt->rgn[r].size;
+	}
+	return p <= (char *)cxt->bph + cxt->max_size;
+}
+
+/* Copy the tree to a newly-allocated region and put things in order */
+static int ft_reorder(struct ft_cxt *cxt, int nextra)
+{
+	unsigned long tot;
+	enum ft_rgn_id r;
+	char *p, *pend;
+	int stroff;
+
+	tot = HDR_SIZE + EXPAND_INCR;
+	for (r = FT_RSVMAP; r <= FT_STRINGS; ++r)
+		tot += cxt->rgn[r].size;
+	if (nextra > 0)
+		tot += nextra;
+	tot = _ALIGN(tot, 8);
+
+	if (!cxt->realloc)
+		return 0;
+	p = cxt->realloc(NULL, tot);
+	if (!p)
+		return 0;
+
+	memcpy(p, cxt->bph, sizeof(struct boot_param_header));
+	/* offsets get fixed up later */
+
+	cxt->bph = (struct boot_param_header *)p;
+	cxt->max_size = tot;
+	pend = p + tot;
+	p += HDR_SIZE;
+
+	memcpy(p, cxt->rgn[FT_RSVMAP].start, cxt->rgn[FT_RSVMAP].size);
+	cxt->rgn[FT_RSVMAP].start = p;
+	p += cxt->rgn[FT_RSVMAP].size;
+
+	memcpy(p, cxt->rgn[FT_STRUCT].start, cxt->rgn[FT_STRUCT].size);
+	ft_node_update_after(cxt, cxt->rgn[FT_STRUCT].start,
+			p - cxt->rgn[FT_STRUCT].start);
+	cxt->p += p - cxt->rgn[FT_STRUCT].start;
+	cxt->rgn[FT_STRUCT].start = p;
+
+	p = pend - cxt->rgn[FT_STRINGS].size;
+	memcpy(p, cxt->rgn[FT_STRINGS].start, cxt->rgn[FT_STRINGS].size);
+	stroff = cxt->str_anchor - cxt->rgn[FT_STRINGS].start;
+	cxt->rgn[FT_STRINGS].start = p;
+	cxt->str_anchor = p + stroff;
+
+	cxt->isordered = 1;
+	return 1;
+}
+
+static inline char *prev_end(struct ft_cxt *cxt, enum ft_rgn_id r)
+{
+	if (r > FT_RSVMAP)
+		return cxt->rgn[r - 1].start + cxt->rgn[r - 1].size;
+	return (char *)cxt->bph + HDR_SIZE;
+}
+
+static inline char *next_start(struct ft_cxt *cxt, enum ft_rgn_id r)
+{
+	if (r < FT_STRINGS)
+		return cxt->rgn[r + 1].start;
+	return (char *)cxt->bph + cxt->max_size;
+}
+
+/*
+ * See if we can expand region rgn by nextra bytes by using up
+ * free space after or before the region.
+ */
+static int ft_shuffle(struct ft_cxt *cxt, char **pp, enum ft_rgn_id rgn,
+		int nextra)
+{
+	char *p = *pp;
+	char *rgn_start, *rgn_end;
+
+	rgn_start = cxt->rgn[rgn].start;
+	rgn_end = rgn_start + cxt->rgn[rgn].size;
+	if (nextra <= 0 || rgn_end + nextra <= next_start(cxt, rgn)) {
+		/* move following stuff */
+		if (p < rgn_end) {
+			if (nextra < 0)
+				memmove(p, p - nextra, rgn_end - p + nextra);
+			else
+				memmove(p + nextra, p, rgn_end - p);
+			if (rgn == FT_STRUCT)
+				ft_node_update_after(cxt, p, nextra);
+		}
+		cxt->rgn[rgn].size += nextra;
+		if (rgn == FT_STRINGS)
+			/* assumes strings only added at beginning */
+			cxt->str_anchor += nextra;
+		return 1;
+	}
+	if (prev_end(cxt, rgn) <= rgn_start - nextra) {
+		/* move preceding stuff */
+		if (p > rgn_start) {
+			memmove(rgn_start - nextra, rgn_start, p - rgn_start);
+			if (rgn == FT_STRUCT)
+				ft_node_update_before(cxt, p, -nextra);
+		}
+		*p -= nextra;
+		cxt->rgn[rgn].start -= nextra;
+		cxt->rgn[rgn].size += nextra;
+		return 1;
+	}
+	return 0;
+}
+
+static int ft_make_space(struct ft_cxt *cxt, char **pp, enum ft_rgn_id rgn,
+			 int nextra)
+{
+	unsigned long size, ssize, tot;
+	char *str, *next;
+	enum ft_rgn_id r;
+
+	if (!cxt->isordered && !ft_reorder(cxt, nextra))
+		return 0;
+	if (ft_shuffle(cxt, pp, rgn, nextra))
+		return 1;
+
+	/* See if there is space after the strings section */
+	ssize = cxt->rgn[FT_STRINGS].size;
+	if (cxt->rgn[FT_STRINGS].start + ssize
+			< (char *)cxt->bph + cxt->max_size) {
+		/* move strings up as far as possible */
+		str = (char *)cxt->bph + cxt->max_size - ssize;
+		cxt->str_anchor += str - cxt->rgn[FT_STRINGS].start;
+		memmove(str, cxt->rgn[FT_STRINGS].start, ssize);
+		cxt->rgn[FT_STRINGS].start = str;
+		/* enough space now? */
+		if (rgn >= FT_STRUCT && ft_shuffle(cxt, pp, rgn, nextra))
+			return 1;
+	}
+
+	/* how much total free space is there following this region? */
+	tot = 0;
+	for (r = rgn; r < FT_STRINGS; ++r) {
+		char *r_end = cxt->rgn[r].start + cxt->rgn[r].size;
+		tot += next_start(cxt, rgn) - r_end;
+	}
+
+	/* cast is to shut gcc up; we know nextra >= 0 */
+	if (tot < (unsigned int)nextra) {
+		/* have to reallocate */
+		char *newp, *new_start;
+		int shift;
+
+		if (!cxt->realloc)
+			return 0;
+		size = _ALIGN(cxt->max_size + (nextra - tot) + EXPAND_INCR, 8);
+		newp = cxt->realloc(cxt->bph, size);
+		if (!newp)
+			return 0;
+		cxt->max_size = size;
+		shift = newp - (char *)cxt->bph;
+
+		if (shift) { /* realloc can return same addr */
+			cxt->bph = (struct boot_param_header *)newp;
+			ft_node_update_after(cxt, cxt->rgn[FT_STRUCT].start,
+					shift);
+			for (r = FT_RSVMAP; r <= FT_STRINGS; ++r) {
+				new_start = cxt->rgn[r].start + shift;
+				cxt->rgn[r].start = new_start;
+			}
+			*pp += shift;
+			cxt->str_anchor += shift;
+		}
+
+		/* move strings up to the end */
+		str = newp + size - ssize;
+		cxt->str_anchor += str - cxt->rgn[FT_STRINGS].start;
+		memmove(str, cxt->rgn[FT_STRINGS].start, ssize);
+		cxt->rgn[FT_STRINGS].start = str;
+
+		if (ft_shuffle(cxt, pp, rgn, nextra))
+			return 1;
+	}
+
+	/* must be FT_RSVMAP and we need to move FT_STRUCT up */
+	if (rgn == FT_RSVMAP) {
+		next = cxt->rgn[FT_RSVMAP].start + cxt->rgn[FT_RSVMAP].size
+			+ nextra;
+		ssize = cxt->rgn[FT_STRUCT].size;
+		if (next + ssize >= cxt->rgn[FT_STRINGS].start)
+			return 0;	/* "can't happen" */
+		memmove(next, cxt->rgn[FT_STRUCT].start, ssize);
+		ft_node_update_after(cxt, cxt->rgn[FT_STRUCT].start, nextra);
+		cxt->rgn[FT_STRUCT].start = next;
+
+		if (ft_shuffle(cxt, pp, rgn, nextra))
+			return 1;
+	}
+
+	return 0;		/* "can't happen" */
+}
+
+static void ft_put_word(struct ft_cxt *cxt, u32 v)
+{
+	*(u32 *) cxt->p = cpu_to_be32(v);
+	cxt->p += 4;
+}
+
+static void ft_put_bin(struct ft_cxt *cxt, const void *data, unsigned int sz)
+{
+	unsigned long sza = _ALIGN(sz, 4);
+
+	/* zero out the alignment gap if necessary */
+	if (sz < sza)
+		*(u32 *) (cxt->p + sza - 4) = 0;
+
+	/* copy in the data */
+	memcpy(cxt->p, data, sz);
+
+	cxt->p += sza;
+}
+
+int ft_begin_node(struct ft_cxt *cxt, const char *name)
+{
+	unsigned long nlen = strlen(name) + 1;
+	unsigned long len = 8 + _ALIGN(nlen, 4);
+
+	if (!ft_make_space(cxt, &cxt->p, FT_STRUCT, len))
+		return -1;
+	ft_put_word(cxt, OF_DT_BEGIN_NODE);
+	ft_put_bin(cxt, name, strlen(name) + 1);
+	return 0;
+}
+
+void ft_end_node(struct ft_cxt *cxt)
+{
+	ft_put_word(cxt, OF_DT_END_NODE);
+}
+
+void ft_nop(struct ft_cxt *cxt)
+{
+	if (ft_make_space(cxt, &cxt->p, FT_STRUCT, 4))
+		ft_put_word(cxt, OF_DT_NOP);
+}
+
+#define NO_STRING	0x7fffffff
+
+static int lookup_string(struct ft_cxt *cxt, const char *name)
+{
+	char *p, *end;
+
+	p = cxt->rgn[FT_STRINGS].start;
+	end = p + cxt->rgn[FT_STRINGS].size;
+	while (p < end) {
+		if (strcmp(p, (char *)name) == 0)
+			return p - cxt->str_anchor;
+		p += strlen(p) + 1;
+	}
+
+	return NO_STRING;
+}
+
+/* lookup string and insert if not found */
+static int map_string(struct ft_cxt *cxt, const char *name)
+{
+	int off;
+	char *p;
+
+	off = lookup_string(cxt, name);
+	if (off != NO_STRING)
+		return off;
+	p = cxt->rgn[FT_STRINGS].start;
+	if (!ft_make_space(cxt, &p, FT_STRINGS, strlen(name) + 1))
+		return NO_STRING;
+	strcpy(p, name);
+	return p - cxt->str_anchor;
+}
+
+int ft_prop(struct ft_cxt *cxt, const char *name, const void *data,
+		unsigned int sz)
+{
+	int off, len;
+
+	off = lookup_string(cxt, name);
+	if (off == NO_STRING)
+		return -1;
+
+	len = 12 + _ALIGN(sz, 4);
+	if (!ft_make_space(cxt, &cxt->p, FT_STRUCT, len))
+		return -1;
+
+	ft_put_word(cxt, OF_DT_PROP);
+	ft_put_word(cxt, sz);
+	ft_put_word(cxt, off);
+	ft_put_bin(cxt, data, sz);
+	return 0;
+}
+
+int ft_prop_str(struct ft_cxt *cxt, const char *name, const char *str)
+{
+	return ft_prop(cxt, name, str, strlen(str) + 1);
+}
+
+int ft_prop_int(struct ft_cxt *cxt, const char *name, unsigned int val)
+{
+	u32 v = cpu_to_be32((u32) val);
+
+	return ft_prop(cxt, name, &v, 4);
+}
+
+/* Calculate the size of the reserved map */
+static unsigned long rsvmap_size(struct ft_cxt *cxt)
+{
+	struct ft_reserve *res;
+
+	res = (struct ft_reserve *)cxt->rgn[FT_RSVMAP].start;
+	while (res->start || res->len)
+		++res;
+	return (char *)(res + 1) - cxt->rgn[FT_RSVMAP].start;
+}
+
+/* Calculate the size of the struct region by stepping through it */
+static unsigned long struct_size(struct ft_cxt *cxt)
+{
+	char *p = cxt->rgn[FT_STRUCT].start;
+	char *next;
+	struct ft_atom atom;
+
+	/* make check in ft_next happy */
+	if (cxt->rgn[FT_STRUCT].size == 0)
+		cxt->rgn[FT_STRUCT].size = 0xfffffffful - (unsigned long)p;
+
+	while ((next = ft_next(cxt, p, &atom)) != NULL)
+		p = next;
+	return p + 4 - cxt->rgn[FT_STRUCT].start;
+}
+
+/* add `adj' on to all string offset values in the struct area */
+static void adjust_string_offsets(struct ft_cxt *cxt, int adj)
+{
+	char *p = cxt->rgn[FT_STRUCT].start;
+	char *next;
+	struct ft_atom atom;
+	int off;
+
+	while ((next = ft_next(cxt, p, &atom)) != NULL) {
+		if (atom.tag == OF_DT_PROP) {
+			off = be32_to_cpu(*(u32 *) (p + 8));
+			*(u32 *) (p + 8) = cpu_to_be32(off + adj);
+		}
+		p = next;
+	}
+}
+
+/* start construction of the flat OF tree from scratch */
+void ft_begin(struct ft_cxt *cxt, void *blob, unsigned int max_size,
+		void *(*realloc_fn) (void *, unsigned long))
+{
+	struct boot_param_header *bph = blob;
+	char *p;
+	struct ft_reserve *pres;
+
+	/* clear the cxt */
+	memset(cxt, 0, sizeof(*cxt));
+
+	cxt->bph = bph;
+	cxt->max_size = max_size;
+	cxt->realloc = realloc_fn;
+	cxt->isordered = 1;
+
+	/* zero everything in the header area */
+	memset(bph, 0, sizeof(*bph));
+
+	bph->magic = cpu_to_be32(OF_DT_HEADER);
+	bph->version = cpu_to_be32(0x10);
+	bph->last_comp_version = cpu_to_be32(0x10);
+
+	/* start pointers */
+	cxt->rgn[FT_RSVMAP].start = p = blob + HDR_SIZE;
+	cxt->rgn[FT_RSVMAP].size = sizeof(struct ft_reserve);
+	pres = (struct ft_reserve *)p;
+	cxt->rgn[FT_STRUCT].start = p += sizeof(struct ft_reserve);
+	cxt->rgn[FT_STRUCT].size = 4;
+	cxt->rgn[FT_STRINGS].start = blob + max_size;
+	cxt->rgn[FT_STRINGS].size = 0;
+
+	/* init rsvmap and struct */
+	pres->start = 0;
+	pres->len = 0;
+	*(u32 *) p = cpu_to_be32(OF_DT_END);
+
+	cxt->str_anchor = blob;
+}
+
+/* open up an existing blob to be examined or modified */
+int ft_open(struct ft_cxt *cxt, void *blob, unsigned int max_size,
+		unsigned int max_find_device,
+		void *(*realloc_fn) (void *, unsigned long))
+{
+	struct boot_param_header *bph = blob;
+
+	/* can't cope with version < 16 */
+	if (be32_to_cpu(bph->version) < 16)
+		return -1;
+
+	/* clear the cxt */
+	memset(cxt, 0, sizeof(*cxt));
+
+	/* alloc node_tbl to track node ptrs returned by ft_find_device */
+	++max_find_device;
+	cxt->node_tbl = realloc_fn(NULL, max_find_device * sizeof(char *));
+	if (!cxt->node_tbl)
+		return -1;
+	memset(cxt->node_tbl, 0, max_find_device * sizeof(char *));
+	cxt->node_max = max_find_device;
+	cxt->nodes_used = 1;	/* don't use idx 0 b/c looks like NULL */
+
+	cxt->bph = bph;
+	cxt->max_size = max_size;
+	cxt->realloc = realloc_fn;
+
+	cxt->rgn[FT_RSVMAP].start = blob + be32_to_cpu(bph->off_mem_rsvmap);
+	cxt->rgn[FT_RSVMAP].size = rsvmap_size(cxt);
+	cxt->rgn[FT_STRUCT].start = blob + be32_to_cpu(bph->off_dt_struct);
+	cxt->rgn[FT_STRUCT].size = struct_size(cxt);
+	cxt->rgn[FT_STRINGS].start = blob + be32_to_cpu(bph->off_dt_strings);
+	cxt->rgn[FT_STRINGS].size = be32_to_cpu(bph->dt_strings_size);
+	/* Leave as '0' to force first ft_make_space call to do a ft_reorder
+	 * and move dt to an area allocated by realloc.
+	cxt->isordered = ft_ordered(cxt);
+	*/
+
+	cxt->p = cxt->rgn[FT_STRUCT].start;
+	cxt->str_anchor = cxt->rgn[FT_STRINGS].start;
+
+	return 0;
+}
+
+/* add a reserver physical area to the rsvmap */
+int ft_add_rsvmap(struct ft_cxt *cxt, u64 physaddr, u64 size)
+{
+	char *p;
+	struct ft_reserve *pres;
+
+	p = cxt->rgn[FT_RSVMAP].start + cxt->rgn[FT_RSVMAP].size
+		- sizeof(struct ft_reserve);
+	if (!ft_make_space(cxt, &p, FT_RSVMAP, sizeof(struct ft_reserve)))
+		return -1;
+
+	pres = (struct ft_reserve *)p;
+	pres->start = cpu_to_be64(physaddr);
+	pres->len = cpu_to_be64(size);
+
+	return 0;
+}
+
+void ft_begin_tree(struct ft_cxt *cxt)
+{
+	cxt->p = cxt->rgn[FT_STRUCT].start;
+}
+
+void ft_end_tree(struct ft_cxt *cxt)
+{
+	struct boot_param_header *bph = cxt->bph;
+	char *p, *oldstr, *str, *endp;
+	unsigned long ssize;
+	int adj;
+
+	if (!cxt->isordered)
+		return;		/* we haven't touched anything */
+
+	/* adjust string offsets */
+	oldstr = cxt->rgn[FT_STRINGS].start;
+	adj = cxt->str_anchor - oldstr;
+	if (adj)
+		adjust_string_offsets(cxt, adj);
+
+	/* make strings end on 8-byte boundary */
+	ssize = cxt->rgn[FT_STRINGS].size;
+	endp = (char *)_ALIGN((unsigned long)cxt->rgn[FT_STRUCT].start
+			+ cxt->rgn[FT_STRUCT].size + ssize, 8);
+	str = endp - ssize;
+
+	/* move strings down to end of structs */
+	memmove(str, oldstr, ssize);
+	cxt->str_anchor = str;
+	cxt->rgn[FT_STRINGS].start = str;
+
+	/* fill in header fields */
+	p = (char *)bph;
+	bph->totalsize = cpu_to_be32(endp - p);
+	bph->off_mem_rsvmap = cpu_to_be32(cxt->rgn[FT_RSVMAP].start - p);
+	bph->off_dt_struct = cpu_to_be32(cxt->rgn[FT_STRUCT].start - p);
+	bph->off_dt_strings = cpu_to_be32(cxt->rgn[FT_STRINGS].start - p);
+	bph->dt_strings_size = cpu_to_be32(ssize);
+}
+
+void *ft_find_device(struct ft_cxt *cxt, const char *srch_path)
+{
+	char *node;
+
+	/* require absolute path */
+	if (srch_path[0] != '/')
+		return NULL;
+	node = ft_find_descendent(cxt, cxt->rgn[FT_STRUCT].start, srch_path);
+	return ft_node_add(cxt, node);
+}
+
+void *ft_find_descendent(struct ft_cxt *cxt, void *top, const char *srch_path)
+{
+	struct ft_atom atom;
+	char *p;
+	const char *cp, *q;
+	int cl;
+	int depth = -1;
+	int dmatch = 0;
+	const char *path_comp[FT_MAX_DEPTH];
+
+	cp = srch_path;
+	cl = 0;
+	p = top;
+
+	while ((p = ft_next(cxt, p, &atom)) != NULL) {
+		switch (atom.tag) {
+		case OF_DT_BEGIN_NODE:
+			++depth;
+			if (depth != dmatch)
+				break;
+			cxt->genealogy[depth] = atom.data;
+			cxt->genealogy[depth + 1] = NULL;
+			if (depth && !(strncmp(atom.name, cp, cl) == 0
+					&& (atom.name[cl] == '/'
+						|| atom.name[cl] == '\0'
+						|| atom.name[cl] == '@')))
+				break;
+			path_comp[dmatch] = cp;
+			/* it matches so far, advance to next path component */
+			cp += cl;
+			/* skip slashes */
+			while (*cp == '/')
+				++cp;
+			/* we're done if this is the end of the string */
+			if (*cp == 0)
+				return atom.data;
+			/* look for end of this component */
+			q = strchr(cp, '/');
+			if (q)
+				cl = q - cp;
+			else
+				cl = strlen(cp);
+			++dmatch;
+			break;
+		case OF_DT_END_NODE:
+			if (depth == 0)
+				return NULL;
+			if (dmatch > depth) {
+				--dmatch;
+				cl = cp - path_comp[dmatch] - 1;
+				cp = path_comp[dmatch];
+				while (cl > 0 && cp[cl - 1] == '/')
+					--cl;
+			}
+			--depth;
+			break;
+		}
+	}
+	return NULL;
+}
+
+void *ft_get_parent(struct ft_cxt *cxt, const void *phandle)
+{
+	void *node;
+	int d;
+	struct ft_atom atom;
+	char *p;
+
+	node = ft_node_ph2node(cxt, phandle);
+	if (node == NULL)
+		return NULL;
+
+	for (d = 0; cxt->genealogy[d] != NULL; ++d)
+		if (cxt->genealogy[d] == node)
+			return cxt->genealogy[d > 0 ? d - 1 : 0];
+
+	/* have to do it the hard way... */
+	p = cxt->rgn[FT_STRUCT].start;
+	d = 0;
+	while ((p = ft_next(cxt, p, &atom)) != NULL) {
+		switch (atom.tag) {
+		case OF_DT_BEGIN_NODE:
+			cxt->genealogy[d] = atom.data;
+			if (node == atom.data) {
+				/* found it */
+				cxt->genealogy[d + 1] = NULL;
+				return d > 0 ? cxt->genealogy[d - 1] : node;
+			}
+			++d;
+			break;
+		case OF_DT_END_NODE:
+			--d;
+			break;
+		}
+	}
+	return NULL;
+}
+
+int ft_get_prop(struct ft_cxt *cxt, const void *phandle, const char *propname,
+		void *buf, const unsigned int buflen)
+{
+	struct ft_atom atom;
+	void *node;
+	char *p;
+	int depth;
+	unsigned int size;
+
+	node = ft_node_ph2node(cxt, phandle);
+	if (node == NULL)
+		return -1;
+
+	depth = 0;
+	p = (char *)node;
+
+	while ((p = ft_next(cxt, p, &atom)) != NULL) {
+		switch (atom.tag) {
+		case OF_DT_BEGIN_NODE:
+			++depth;
+			break;
+		case OF_DT_PROP:
+			if ((depth != 1) || strcmp(atom.name, propname))
+				break;
+			size = min(atom.size, buflen);
+			memcpy(buf, atom.data, size);
+			return atom.size;
+		case OF_DT_END_NODE:
+			if (--depth <= 0)
+				return -1;
+		}
+	}
+	return -1;
+}
+
+int ft_set_prop(struct ft_cxt *cxt, const void *phandle, const char *propname,
+		const void *buf, const unsigned int buflen)
+{
+	struct ft_atom atom;
+	void *node;
+	char *p, *next;
+	int nextra, depth;
+
+	node = ft_node_ph2node(cxt, phandle);
+	if (node == NULL)
+		return -1;
+
+	depth = 0;
+	p = node;
+
+	while ((next = ft_next(cxt, p, &atom)) != NULL) {
+		switch (atom.tag) {
+		case OF_DT_BEGIN_NODE:
+			++depth;
+			break;
+		case OF_DT_END_NODE:
+			if (--depth > 0)
+				break;
+			/* haven't found the property, insert here */
+			cxt->p = p;
+			return ft_prop(cxt, propname, buf, buflen);
+		case OF_DT_PROP:
+			if ((depth != 1) || strcmp(atom.name, propname))
+				break;
+			/* found an existing property, overwrite it */
+			nextra = _ALIGN(buflen, 4) - _ALIGN(atom.size, 4);
+			cxt->p = atom.data;
+			if (nextra && !ft_make_space(cxt, &cxt->p, FT_STRUCT,
+						nextra))
+				return -1;
+			*(u32 *) (cxt->p - 8) = cpu_to_be32(buflen);
+			ft_put_bin(cxt, buf, buflen);
+			return 0;
+		}
+		p = next;
+	}
+	return -1;
+}
+
+int ft_del_prop(struct ft_cxt *cxt, const void *phandle, const char *propname)
+{
+	struct ft_atom atom;
+	void *node;
+	char *p, *next;
+	int size;
+
+	node = ft_node_ph2node(cxt, phandle);
+	if (node == NULL)
+		return -1;
+
+	p = node;
+	while ((next = ft_next(cxt, p, &atom)) != NULL) {
+		switch (atom.tag) {
+		case OF_DT_BEGIN_NODE:
+		case OF_DT_END_NODE:
+			return -1;
+		case OF_DT_PROP:
+			if (strcmp(atom.name, propname))
+				break;
+			/* found the property, remove it */
+			size = 12 + -_ALIGN(atom.size, 4);
+			cxt->p = p;
+			if (!ft_make_space(cxt, &cxt->p, FT_STRUCT, -size))
+				return -1;
+			return 0;
+		}
+		p = next;
+	}
+	return -1;
+}
+
+void *ft_create_node(struct ft_cxt *cxt, const void *parent, const char *path)
+{
+	struct ft_atom atom;
+	char *p, *next;
+	int depth = 0;
+
+	p = cxt->rgn[FT_STRUCT].start;
+	while ((next = ft_next(cxt, p, &atom)) != NULL) {
+		switch (atom.tag) {
+		case OF_DT_BEGIN_NODE:
+			++depth;
+			if (depth == 1 && strcmp(atom.name, path) == 0)
+				/* duplicate node path, return error */
+				return NULL;
+			break;
+		case OF_DT_END_NODE:
+			--depth;
+			if (depth > 0)
+				break;
+			/* end of node, insert here */
+			cxt->p = p;
+			ft_begin_node(cxt, path);
+			ft_end_node(cxt);
+			return p;
+		}
+		p = next;
+	}
+	return NULL;
+}