[RFC PATCH 03/12] of: base: record root node in interator and use it for phandle lookup

Enrico Weigelt, metux IT consult
2021-02-08T22:26:07Z

For detached oftree support, find the root node and record it, on iterator
creation. If we find the root of the global oftree, record NULL, in order to
have a clear distinction between detached and non-detached cases. The recorded
root node is then used for resolving phandles.

Note that in the detached case, phandle cache can't be used, so we have a
little performance penalty on repeated phandle lookups.

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
---
drivers/of/base.c | 13 ++++++++++++-
include/linux/of.h | 1 +
2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index 6b3d1e817808..e5ef611ed233 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -1249,6 +1249,7 @@ int of_phandle_iterator_init(struct of_phandle_iterator *it,
{
const __be32 *list;
int size;
+ struct device_node *walk;

memset(it, 0, sizeof(*it));

@@ -1270,6 +1271,16 @@ int of_phandle_iterator_init(struct of_phandle_iterator *it,
it->phandle_end = list;
it->cur = list;

+ /*
+ * find the root of our tree and record it, if we're dealing with an
+ * detached oftree - in non-detached case, we record NULL, for clear
+ * distinction between these two cases.
+ */
+ for (walk=(struct device_node*)np;
+ walk->parent;
+ walk=(struct device_node*)walk->parent);
+ it->root = ((walk == of_root) ? NULL : walk);
+
return 0;
}
EXPORT_SYMBOL_GPL(of_phandle_iterator_init);
@@ -1297,7 +1308,7 @@ int of_phandle_iterator_next(struct of_phandle_iterator *it)
* Find the provider node and parse the #*-cells property to
* determine the argument length.
*/
- it->node = of_find_node_by_phandle(it->phandle);
+ it->node = of_find_node_by_phandle_from(it->root, it->phandle);

if (it->cells_name) {
if (!it->node) {
diff --git a/include/linux/of.h b/include/linux/of.h
index c285141653e5..dbf2c7442389 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -82,6 +82,7 @@ struct of_phandle_iterator {
const char *cells_name;
int cell_count;
const struct device_node *parent;
+ struct device_node *root;

/* List size information */
const __be32 *list_end;
--
2.11.0