2 files changed, 31 insertions, 3 deletions

diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c
index 138e72f74377..a6386b3a3c15 100644
--- a/drivers/pinctrl/core.c
+++ b/drivers/pinctrl/core.c
@@ -43,6 +43,8 @@ struct pinctrl_maps {
         unsigned num_maps;
 };
 
+static bool pinctrl_dummy_state;
+
 /* Mutex taken by all entry points */
 DEFINE_MUTEX(pinctrl_mutex);
 
@@ -61,6 +63,19 @@ static LIST_HEAD(pinctrl_maps);
                         _i_ < _maps_node_->num_maps; \
                         i++, _map_ = &_maps_node_->maps[_i_])
 
+/**
+ * pinctrl_provide_dummies() - indicate if pinctrl provides dummy state support
+ *
+ * Usually this function is called by platforms without pinctrl driver support
+ * but run with some shared drivers using pinctrl APIs.
+ * After calling this function, the pinctrl core will return successfully
+ * with creating a dummy state for the driver to keep going smoothly.
+ */
+void pinctrl_provide_dummies(void)
+{
+        pinctrl_dummy_state = true;
+}
+
 const char *pinctrl_dev_get_name(struct pinctrl_dev *pctldev)
 {
         /* We're not allowed to register devices without name */
@@ -719,8 +734,18 @@ static struct pinctrl_state *pinctrl_lookup_state_locked(struct pinctrl *p,
         struct pinctrl_state *state;
 
         state = find_state(p, name);
-        if (!state)
-                return ERR_PTR(-ENODEV);
+        if (!state) {
+                if (pinctrl_dummy_state) {
+                        /* create dummy state */
+                        dev_dbg(p->dev, "using pinctrl dummy state (%s)\n",
+                                name);
+                        state = create_state(p, name);
+                        if (IS_ERR(state))
+                                return state;
+                } else {
+                        return ERR_PTR(-ENODEV);
+                }
+        }
 
         return state;
 }
diff --git a/include/linux/pinctrl/machine.h b/include/linux/pinctrl/machine.h
index 9c4a19867289..7d22ab00343f 100644
--- a/include/linux/pinctrl/machine.h
+++ b/include/linux/pinctrl/machine.h
@@ -154,7 +154,7 @@ struct pinctrl_map {
 
 extern int pinctrl_register_mappings(struct pinctrl_map const *map,
                                 unsigned num_maps);
-
+extern void pinctrl_provide_dummies(void);
 #else
 
 static inline int pinctrl_register_mappings(struct pinctrl_map const *map,
@@ -163,5 +163,8 @@ static inline int pinctrl_register_mappings(struct pinctrl_map const *map,
         return 0;
 }
 
+static inline void pinctrl_provide_dummies(void)
+{
+}
 #endif /* !CONFIG_PINCTRL */
 #endif