libfdt: Enhanced and published fdt_next_tag()
Enhanced the formerly private function _fdt_next_tag() to allow stepping
through the tree, used to produce a human-readable dump, and made
it part of the published interface.
Also added some comments.
diff --git a/libfdt/fdt_ro.c b/libfdt/fdt_ro.c
index 9112c6a..f884083 100644
--- a/libfdt/fdt_ro.c
+++ b/libfdt/fdt_ro.c
@@ -48,11 +48,24 @@
return 1;
}
+/*
+ * Return a pointer to the string at the given string offset.
+ */
char *fdt_string(const void *fdt, int stroffset)
{
return (char *)fdt + fdt_off_dt_strings(fdt) + stroffset;
}
+/*
+ * Return the node offset of the node specified by:
+ * parentoffset - starting place (0 to start at the root)
+ * name - name being searched for
+ * namelen - length of the name: typically strlen(name)
+ *
+ * Notes:
+ * If the start node has subnodes, the subnodes are _not_ searched for the
+ * requested name.
+ */
int fdt_subnode_offset_namelen(const void *fdt, int parentoffset,
const char *name, int namelen)
{
@@ -62,13 +75,13 @@
CHECK_HEADER(fdt);
- tag = _fdt_next_tag(fdt, parentoffset, &nextoffset);
+ tag = fdt_next_tag(fdt, parentoffset, &nextoffset, NULL);
if (tag != FDT_BEGIN_NODE)
return -FDT_ERR_BADOFFSET;
do {
offset = nextoffset;
- tag = _fdt_next_tag(fdt, offset, &nextoffset);
+ tag = fdt_next_tag(fdt, offset, &nextoffset, NULL);
switch (tag) {
case FDT_END:
@@ -76,10 +89,15 @@
case FDT_BEGIN_NODE:
level++;
+ /*
+ * If we are nested down levels, ignore the strings
+ * until we get back to the proper level.
+ */
if (level != 1)
continue;
+
+ /* Return the offset if this is "our" string. */
if (offset_streq(fdt, offset+FDT_TAGSIZE, name, namelen))
- /* Found it! */
return offset;
break;
@@ -99,12 +117,19 @@
return -FDT_ERR_NOTFOUND;
}
+/*
+ * See fdt_subnode_offset_namelen()
+ */
int fdt_subnode_offset(const void *fdt, int parentoffset,
const char *name)
{
return fdt_subnode_offset_namelen(fdt, parentoffset, name, strlen(name));
}
+/*
+ * Searches for the node corresponding to the given path and returns the
+ * offset of that node.
+ */
int fdt_path_offset(const void *fdt, const char *path)
{
const char *end = path + strlen(path);
@@ -113,21 +138,33 @@
CHECK_HEADER(fdt);
+ /* Paths must be absolute */
if (*path != '/')
return -FDT_ERR_BADPATH;
while (*p) {
const char *q;
+ /* Skip path separator(s) */
while (*p == '/')
p++;
if (! *p)
return -FDT_ERR_BADPATH;
+
+ /*
+ * Find the next path separator. The characters between
+ * p and q are the next segment of the the path to find.
+ */
q = strchr(p, '/');
if (! q)
q = end;
+ /*
+ * Find the offset corresponding to the this path segment.
+ */
offset = fdt_subnode_offset_namelen(fdt, offset, p, q-p);
+
+ /* Oops, error, abort abort abort */
if (offset < 0)
return offset;
@@ -137,6 +174,10 @@
return offset;
}
+/*
+ * Given the offset of a node and a name of a property in that node, return
+ * a pointer to the property struct.
+ */
struct fdt_property *fdt_get_property(const void *fdt,
int nodeoffset,
const char *name, int *lenp)
@@ -155,14 +196,14 @@
if (nodeoffset % FDT_TAGSIZE)
goto fail;
- tag = _fdt_next_tag(fdt, nodeoffset, &nextoffset);
+ tag = fdt_next_tag(fdt, nodeoffset, &nextoffset, NULL);
if (tag != FDT_BEGIN_NODE)
goto fail;
do {
offset = nextoffset;
- tag = _fdt_next_tag(fdt, offset, &nextoffset);
+ tag = fdt_next_tag(fdt, offset, &nextoffset, NULL);
switch (tag) {
case FDT_END:
err = -FDT_ERR_TRUNCATED;
@@ -177,6 +218,10 @@
break;
case FDT_PROP:
+ /*
+ * If we are nested down levels, ignore the strings
+ * until we get back to the proper level.
+ */
if (level != 0)
continue;
@@ -216,6 +261,10 @@
return NULL;
}
+/*
+ * Given the offset of a node and a name of a property in that node, return
+ * a pointer to the property data (ONLY).
+ */
void *fdt_getprop(const void *fdt, int nodeoffset,
const char *name, int *lenp)
{
@@ -225,5 +274,60 @@
if (! prop)
return NULL;
+ return (void *)prop->data;
+}
+
+
+uint32_t fdt_next_tag(const void *fdt, int offset, int *nextoffset, char **namep)
+{
+ const uint32_t *tagp, *lenp;
+ uint32_t tag;
+ const char *p;
+
- return prop->data;
+ if (offset % FDT_TAGSIZE)
+ return -1;
+
+ tagp = fdt_offset_ptr(fdt, offset, FDT_TAGSIZE);
+ if (! tagp)
+ return FDT_END; /* premature end */
+ tag = fdt32_to_cpu(*tagp);
+ offset += FDT_TAGSIZE;
+
+ switch (tag) {
+ case FDT_BEGIN_NODE:
+ if(namep)
+ *namep = fdt_offset_ptr(fdt, offset, 1);
+
+ /* skip name */
+ do {
+ p = fdt_offset_ptr(fdt, offset++, 1);
+ } while (p && (*p != '\0'));
+ if (! p)
+ return FDT_END;
+ break;
+ case FDT_PROP:
+ lenp = fdt_offset_ptr(fdt, offset, sizeof(*lenp));
+ if (! lenp)
+ return FDT_END;
+ /*
+ * Get the property and set the namep to the name.
+ */
+ if(namep) {
+ struct fdt_property *prop;
+
+ prop = fdt_offset_ptr_typed(fdt, offset - FDT_TAGSIZE, prop);
+ if (! prop)
+ return -FDT_ERR_BADSTRUCTURE;
+ *namep = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
+ }
+ /* skip name offset, length and value */
+ offset += 2*FDT_TAGSIZE + fdt32_to_cpu(*lenp);
+ break;
+ }
+
+ if (nextoffset)
+ *nextoffset = ALIGN(offset, FDT_TAGSIZE);
+
+ return tag;
}
+