of: Add helper for getting the maximum alias index for a stem

of_alias_max_index will return the maximum number for which an
alias of a given stem exists. This is useful for frameworks
whishing to reserve a number of device slots from dynamic
allocation.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
(cherry picked from commit 18ae7362e9822993436c1a544e49cfd58fa175b2)

1 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/of.h b/include/linux/of.h
index 668e12322dd4..7a07fa495bc7 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -286,6 +286,7 @@ extern int of_count_phandle_with_args(const struct device_node *np,
 
 extern void of_alias_scan(void * (*dt_alloc)(u64 size, u64 align));
 extern int of_alias_get_id(struct device_node *np, const char *stem);
+extern int of_alias_max_index(const char *stem);
 
 extern int of_machine_is_compatible(const char *compat);
 
@@ -503,6 +504,11 @@ static inline int of_alias_get_id(struct device_node *np, const char *stem)
         return -ENOSYS;
 }
 
+static inline int of_alias_max_index(const char *stem)
+{
+        return -ENODEV;
+}
+
 static inline int of_machine_is_compatible(const char *compat)
 {
         return 0;