1 files changed, 22 insertions, 0 deletions

diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c
index 1038c381aea..d94e0ce7827 100644
--- a/drivers/i2c/i2c-mux.c
+++ b/drivers/i2c/i2c-mux.c
@@ -88,9 +88,23 @@ static u32 i2c_mux_functionality(struct i2c_adapter *adap)
         return parent->algo->functionality(parent);
 }
 
+/* Return all parent classes, merged */
+static unsigned int i2c_mux_parent_classes(struct i2c_adapter *parent)
+{
+        unsigned int class = 0;
+
+        do {
+                class |= parent->class;
+                parent = i2c_parent_is_i2c_adapter(parent);
+        } while (parent);
+
+        return class;
+}
+
 struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
                                 struct device *mux_dev,
                                 void *mux_priv, u32 force_nr, u32 chan_id,
+                                unsigned int class,
                                 int (*select) (struct i2c_adapter *,
                                                void *, u32),
                                 int (*deselect) (struct i2c_adapter *,
@@ -127,6 +141,14 @@ struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
         priv->adap.algo_data = priv;
         priv->adap.dev.parent = &parent->dev;
 
+        /* Sanity check on class */
+        if (i2c_mux_parent_classes(parent) & class)
+                dev_err(&parent->dev,
+                        "Segment %d behind mux can't share classes with ancestors\n",
+                        chan_id);
+        else
+                priv->adap.class = class;
+
         /*
          * Try to populate the mux adapter's of_node, expands to
          * nothing if !CONFIG_OF.