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.c b/lib/libfdt/fdt.c
index b09ea6f..4157b21 100644
--- a/lib/libfdt/fdt.c
+++ b/lib/libfdt/fdt.c
@@ -153,6 +153,15 @@
return offset;
}
+int _fdt_check_prop_offset(const void *fdt, int offset)
+{
+ if ((offset < 0) || (offset % FDT_TAGSIZE)
+ || (fdt_next_tag(fdt, offset, &offset) != FDT_PROP))
+ return -FDT_ERR_BADOFFSET;
+
+ return offset;
+}
+
int fdt_next_node(const void *fdt, int offset, int *depth)
{
int nextoffset = 0;