Support ePAPR compliant phandle properties

Currently, the Linux kernel, libfdt and dtc, when using flattened
device trees encode a node's phandle into a property named
"linux,phandle".  The ePAPR specification, however - aiming as it is
to not be a Linux specific spec - requires that phandles be encoded in
a property named simply "phandle".

This patch adds support for this newer approach to dtc and libfdt.
Specifically:

	- fdt_get_phandle() will now return the correct phandle if it
          is supplied in either of these properties

	- fdt_node_offset_by_phandle() will correctly find a node with
          the given phandle encoded in either property.

	- By default, when auto-generating phandles, dtc will encode
          it into both properties for maximum compatibility.  A new -H
          option allows either only old-style or only new-style
          properties to be generated.

	- If phandle properties are explicitly supplied in the dts
	  file, dtc will not auto-generate ones in the alternate format.

	- If both properties are supplied, dtc will check that they
          have the same value.

	- Some existing testcases are updated to use a mix of old and
          new-style phandles, partially testing the changes.

	- A new phandle_format test further tests the libfdt support,
          and the -H option.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

This was extracted from the DTC commit:
d75b33af676d0beac8398651a7f09037555a550b Mon Sep 17 00:00:00 2001

Signed-off-by: Gerald Van Baren <vanbaren@cideas.com>

1 files changed, 27 insertions, 6 deletions

diff --git a/lib/libfdt/fdt_ro.c b/lib/libfdt/fdt_ro.c
index 1e1e32209ce..91a354e108a 100644
--- a/lib/libfdt/fdt_ro.c
+++ b/lib/libfdt/fdt_ro.c
@@ -278,9 +278,14 @@ uint32_t fdt_get_phandle(const void *fdt, int nodeoffset)
 	const uint32_t *php;
 	int len;
 
-	php = fdt_getprop(fdt, nodeoffset, "linux,phandle", &len);
-	if (!php || (len != sizeof(*php)))
-		return 0;
+	/* FIXME: This is a bit sub-optimal, since we potentially scan
+	 * over all the properties twice. */
+	php = fdt_getprop(fdt, nodeoffset, "phandle", &len);
+	if (!php || (len != sizeof(*php))) {
+		php = fdt_getprop(fdt, nodeoffset, "linux,phandle", &len);
+		if (!php || (len != sizeof(*php)))
+			return 0;
+	}
 
 	return fdt32_to_cpu(*php);
 }
@@ -440,11 +445,27 @@ int fdt_node_offset_by_prop_value(const void *fdt, int startoffset,
 
 int fdt_node_offset_by_phandle(const void *fdt, uint32_t phandle)
 {
+	int offset;
+
 	if ((phandle == 0) || (phandle == -1))
 		return -FDT_ERR_BADPHANDLE;
-	phandle = cpu_to_fdt32(phandle);
-	return fdt_node_offset_by_prop_value(fdt, -1, "linux,phandle",
-					     &phandle, sizeof(phandle));
+
+	FDT_CHECK_HEADER(fdt);
+
+	/* FIXME: The algorithm here is pretty horrible: we
+	 * potentially scan each property of a node in
+	 * fdt_get_phandle(), then if that didn't find what
+	 * we want, we scan over them again making our way to the next
+	 * node.  Still it's the easiest to implement approach;
+	 * performance can come later. */
+	for (offset = fdt_next_node(fdt, -1, NULL);
+	     offset >= 0;
+	     offset = fdt_next_node(fdt, offset, NULL)) {
+		if (fdt_get_phandle(fdt, offset) == phandle)
+			return offset;
+	}
+
+	return offset; /* error from fdt_next_node() */
 }
 
 static int _fdt_stringlist_contains(const char *strlist, int listlen,