[PATCH 1/2] device property: Add optional nargs_prop for get_reference_args

[Sean Anderson]

get_reference_args does not permit falling back to nargs when nargs_prop
is missing. This makes it difficult to support older devicetrees where
nargs_prop may not be present. Add support for this by converting nargs
to a signed value. Where before nargs was ignored if nargs_prop was
passed, now nargs is only ignored if it is strictly negative. When it is
positive, nargs represents the fallback cells to use if nargs_prop is
absent.

Signed-off-by: Sean Anderson <sean.anderson@xxxxxxxxx>
---

 drivers/base/property.c |  4 ++--
 drivers/base/swnode.c   | 13 +++++++++----
 drivers/of/property.c   | 10 +++-------
 include/linux/fwnode.h  |  2 +-
 4 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/drivers/base/property.c b/drivers/base/property.c
index c1392743df9c..049f8a6088a1 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c
@@ -606,7 +606,7 @@ int fwnode_property_get_reference_args(const struct fwnode_handle *fwnode,
 		return -ENOENT;
 
 	ret = fwnode_call_int_op(fwnode, get_reference_args, prop, nargs_prop,
-				 nargs, index, args);
+				 nargs_prop ? -1 : nargs, index, args);
 	if (ret == 0)
 		return ret;
 
@@ -614,7 +614,7 @@ int fwnode_property_get_reference_args(const struct fwnode_handle *fwnode,
 		return ret;
 
 	return fwnode_call_int_op(fwnode->secondary, get_reference_args, prop, nargs_prop,
-				  nargs, index, args);
+				  nargs_prop ? -1 : nargs, index, args);
 }
 EXPORT_SYMBOL_GPL(fwnode_property_get_reference_args);
 
diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c
index b1726a3515f6..11af2001478f 100644
--- a/drivers/base/swnode.c
+++ b/drivers/base/swnode.c
@@ -503,7 +503,7 @@ software_node_get_named_child_node(const struct fwnode_handle *fwnode,
 static int
 software_node_get_reference_args(const struct fwnode_handle *fwnode,
 				 const char *propname, const char *nargs_prop,
-				 unsigned int nargs, unsigned int index,
+				 int nargs, unsigned int index,
 				 struct fwnode_reference_args *args)
 {
 	struct swnode *swnode = to_swnode(fwnode);
@@ -543,10 +543,15 @@ software_node_get_reference_args(const struct fwnode_handle *fwnode,
 		error = property_entry_read_int_array(ref->node->properties,
 						      nargs_prop, sizeof(u32),
 						      &nargs_prop_val, 1);
-		if (error)
+
+		if (error == -EINVAL) {
+			if (nargs < 0)
+				return error;
+		} else if (error) {
 			return error;
-
-		nargs = nargs_prop_val;
+		} else {
+			nargs = nargs_prop_val;
+		}
 	}
 
 	if (nargs > NR_FWNODE_REFERENCE_ARGS)
diff --git a/drivers/of/property.c b/drivers/of/property.c
index c1feb631e383..c41190e47111 100644
--- a/drivers/of/property.c
+++ b/drivers/of/property.c
@@ -1116,19 +1116,15 @@ of_fwnode_get_named_child_node(const struct fwnode_handle *fwnode,
 static int
 of_fwnode_get_reference_args(const struct fwnode_handle *fwnode,
 			     const char *prop, const char *nargs_prop,
-			     unsigned int nargs, unsigned int index,
+			     int nargs, unsigned int index,
 			     struct fwnode_reference_args *args)
 {
 	struct of_phandle_args of_args;
 	unsigned int i;
 	int ret;
 
-	if (nargs_prop)
-		ret = of_parse_phandle_with_args(to_of_node(fwnode), prop,
-						 nargs_prop, index, &of_args);
-	else
-		ret = of_parse_phandle_with_fixed_args(to_of_node(fwnode), prop,
-						       nargs, index, &of_args);
+	ret = __of_parse_phandle_with_args(to_of_node(fwnode), prop, nargs_prop,
+					   nargs, index, &of_args);
 	if (ret < 0)
 		return ret;
 	if (!args) {
diff --git a/include/linux/fwnode.h b/include/linux/fwnode.h
index 6fa0a268d538..69fe44c68f8c 100644
--- a/include/linux/fwnode.h
+++ b/include/linux/fwnode.h
@@ -163,7 +163,7 @@ struct fwnode_operations {
 				const char *name);
 	int (*get_reference_args)(const struct fwnode_handle *fwnode,
 				  const char *prop, const char *nargs_prop,
-				  unsigned int nargs, unsigned int index,
+				  int nargs, unsigned int index,
 				  struct fwnode_reference_args *args);
 	struct fwnode_handle *
 	(*graph_get_next_endpoint)(const struct fwnode_handle *fwnode,
-- 
2.35.1.1320.gc452695387.dirty