libfdt: Implement property iteration functions
For ages, we've been talking about adding functions to libfdt to allow
iteration through properties. So, finally, here are some.
I got bogged down on this for a long time because I didn't want to
expose offsets directly to properties to the callers. But without
that, attempting to make reasonable iteration functions just became
horrible. So eventually, I settled on an interface which does now
expose property offsets. fdt_first_property_offset() and
fdt_next_property_offset() are used to step through the offsets of the
properties starting from a particularly node offset. The details of
the property at each offset can then be retrieved with either
fdt_get_property_by_offset() or fdt_getprop_by_offset() which have
interfaces similar to fdt_get_property() and fdt_getprop()
respectively.
No explicit testcases are included, but we do use the new functions to
reimplement the existing fdt_get_property() function.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This was extracted from the DTC commit:
73dca9ae0b9abe6924ba640164ecce9f8df69c5a Mon Sep 17 00:00:00 2001
Signed-off-by: Gerald Van Baren <vanbaren@cideas.com>
diff --git a/lib/libfdt/fdt_ro.c b/lib/libfdt/fdt_ro.c
index 91a354e..1933010 100644
--- a/lib/libfdt/fdt_ro.c
+++ b/lib/libfdt/fdt_ro.c
@@ -109,6 +109,30 @@
return i;
}
+static int _nextprop(const void *fdt, int offset)
+{
+ uint32_t tag;
+ int nextoffset;
+
+ do {
+ tag = fdt_next_tag(fdt, offset, &nextoffset);
+
+ switch (tag) {
+ case FDT_END:
+ if (nextoffset >= 0)
+ return -FDT_ERR_BADSTRUCTURE;
+ else
+ return nextoffset;
+
+ case FDT_PROP:
+ return offset;
+ }
+ offset = nextoffset;
+ } while (tag == FDT_NOP);
+
+ return -FDT_ERR_NOTFOUND;
+}
+
int fdt_subnode_offset_namelen(const void *fdt, int offset,
const char *name, int namelen)
{
@@ -198,52 +222,66 @@
return NULL;
}
+int fdt_first_property_offset(const void *fdt, int nodeoffset)
+{
+ int offset;
+
+ if ((offset = _fdt_check_node_offset(fdt, nodeoffset)) < 0)
+ return offset;
+
+ return _nextprop(fdt, offset);
+}
+
+int fdt_next_property_offset(const void *fdt, int offset)
+{
+ if ((offset = _fdt_check_prop_offset(fdt, offset)) < 0)
+ return offset;
+
+ return _nextprop(fdt, offset);
+}
+
+const struct fdt_property *fdt_get_property_by_offset(const void *fdt,
+ int offset,
+ int *lenp)
+{
+ int err;
+ const struct fdt_property *prop;
+
+ if ((err = _fdt_check_prop_offset(fdt, offset)) < 0) {
+ if (lenp)
+ *lenp = err;
+ return NULL;
+ }
+
+ prop = _fdt_offset_ptr(fdt, offset);
+
+ if (lenp)
+ *lenp = fdt32_to_cpu(prop->len);
+
+ return prop;
+}
+
const struct fdt_property *fdt_get_property_namelen(const void *fdt,
- int nodeoffset,
+ int offset,
const char *name,
int namelen, int *lenp)
{
- uint32_t tag;
- const struct fdt_property *prop;
- int offset, nextoffset;
- int err;
+ for (offset = fdt_first_property_offset(fdt, offset);
+ (offset >= 0);
+ (offset = fdt_next_property_offset(fdt, offset))) {
+ const struct fdt_property *prop;
- if (((err = fdt_check_header(fdt)) != 0)
- || ((err = _fdt_check_node_offset(fdt, nodeoffset)) < 0))
- goto fail;
-
- nextoffset = err;
- do {
- offset = nextoffset;
-
- tag = fdt_next_tag(fdt, offset, &nextoffset);
- switch (tag) {
- case FDT_END:
- if (nextoffset < 0)
- err = nextoffset;
- else
- /* FDT_END tag with unclosed nodes */
- err = -FDT_ERR_BADSTRUCTURE;
- goto fail;
-
- case FDT_PROP:
- prop = _fdt_offset_ptr(fdt, offset);
- if (_fdt_string_eq(fdt, fdt32_to_cpu(prop->nameoff),
- name, namelen)) {
- /* Found it! */
- if (lenp)
- *lenp = fdt32_to_cpu(prop->len);
-
- return prop;
- }
+ if (!(prop = fdt_get_property_by_offset(fdt, offset, lenp))) {
+ offset = -FDT_ERR_INTERNAL;
break;
}
- } while ((tag != FDT_BEGIN_NODE) && (tag != FDT_END_NODE));
+ if (_fdt_string_eq(fdt, fdt32_to_cpu(prop->nameoff),
+ name, namelen))
+ return prop;
+ }
- err = -FDT_ERR_NOTFOUND;
- fail:
if (lenp)
- *lenp = err;
+ *lenp = offset;
return NULL;
}
@@ -267,6 +305,19 @@
return prop->data;
}
+const void *fdt_getprop_by_offset(const void *fdt, int offset,
+ const char **namep, int *lenp)
+{
+ const struct fdt_property *prop;
+
+ prop = fdt_get_property_by_offset(fdt, offset, lenp);
+ if (!prop)
+ return NULL;
+ if (namep)
+ *namep = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
+ return prop->data;
+}
+
const void *fdt_getprop(const void *fdt, int nodeoffset,
const char *name, int *lenp)
{