of: report whether of_diff found differences in return code

Tests may want to leverage of_diff to verify that fixups proceeded as
expected. of_diff lends itself nicely to that by being silent in case of
success and just reporting diff on error. Add a return code to make it
usable in follow-up tests.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.barebox.org/20220207082801.1052894-3-a.fatoum@pengutronix.de
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

3 files changed, 12 insertions, 7 deletions

diff --git a/commands/of_diff.c b/commands/of_diff.c
index fa99fcd641..6a78263200 100644
--- a/commands/of_diff.c
+++ b/commands/of_diff.c
@@ -77,9 +77,7 @@ static int do_of_diff(int argc, char *argv[])
 		goto out;
 	}
 
-	of_diff(a, b, 0);
-
-	ret = 0;
+	ret = of_diff(a, b, 0) ? COMMAND_ERROR : COMMAND_SUCCESS;
 out:
 	if (a && a != root)
 		of_delete_node(a);
diff --git a/drivers/of/base.c b/drivers/of/base.c
index 80465d6d50..99be242542 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -2077,15 +2077,16 @@ static void of_print_close(struct device_node *node, int *printed)
  * This function compares two device trees against each other and prints
  * a diff-like result.
  */
-void of_diff(struct device_node *a, struct device_node *b, int indent)
+int of_diff(struct device_node *a, struct device_node *b, int indent)
 {
 	struct property *ap, *bp;
 	struct device_node *ca, *cb;
-	int printed = 0;
+	int printed = 0, diff = 0;
 
 	list_for_each_entry(ap, &a->properties, list) {
 		bp = of_find_property(b, ap->name, NULL);
 		if (!bp) {
+			diff++;
 			of_print_parents(a, &printed);
 			printf("- ");
 			__of_print_property(ap, indent);
@@ -2093,6 +2094,7 @@ void of_diff(struct device_node *a, struct device_node *b, int indent)
 		}
 
 		if (ap->length != bp->length || memcmp(of_property_get_value(ap), of_property_get_value(bp), bp->length)) {
+			diff++;
 			of_print_parents(a, &printed);
 			printf("- ");
 			__of_print_property(ap, indent);
@@ -2104,6 +2106,7 @@ void of_diff(struct device_node *a, struct device_node *b, int indent)
 	list_for_each_entry(bp, &b->properties, list) {
 		ap = of_find_property(a, bp->name, NULL);
 		if (!ap) {
+			diff++;
 			of_print_parents(a, &printed);
 			printf("+ ");
 			__of_print_property(bp, indent);
@@ -2113,8 +2116,9 @@ void of_diff(struct device_node *a, struct device_node *b, int indent)
 	for_each_child_of_node(a, ca) {
 		cb = of_get_child_by_name(b, ca->name);
 		if (cb) {
-			of_diff(ca, cb, indent + 1);
+			diff += of_diff(ca, cb, indent + 1);
 		} else {
+			diff++;
 			of_print_parents(a, &printed);
 			__of_print_nodes(ca, indent, "- ");
 		}
@@ -2122,12 +2126,15 @@ void of_diff(struct device_node *a, struct device_node *b, int indent)
 
 	for_each_child_of_node(b, cb) {
 		if (!of_get_child_by_name(a, cb->name)) {
+			diff++;
 			of_print_parents(a, &printed);
 			__of_print_nodes(cb, indent, "+ ");
 		}
 	}
 
 	of_print_close(a, &printed);
+
+	return diff;
 }
 
 struct device_node *of_new_node(struct device_node *parent, const char *name)
diff --git a/include/of.h b/include/of.h
index 216d0ee763..b449d10ec7 100644
--- a/include/of.h
+++ b/include/of.h
@@ -107,7 +107,7 @@ void of_print_cmdline(struct device_node *root);
 
 void of_print_nodes(struct device_node *node, int indent);
 void of_print_properties(struct device_node *node);
-void of_diff(struct device_node *a, struct device_node *b, int indent);
+int of_diff(struct device_node *a, struct device_node *b, int indent);
 int of_probe(void);
 int of_parse_dtb(struct fdt_header *fdt);
 struct device_node *of_unflatten_dtb(const void *fdt, int size);