i2c: core: manage i2c bus device refcount in i2c_[get|put]_adapter

In addition to module_get()/module_put() add get_device()/put_device()
calls into i2c_get_adapter()/i2c_put_adapter() exported
interfaces. This is done to lock I2C bus device, if it is in use by a
client.
Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

drivers/i2c/i2c-core.c

@@ -2413,9 +2413,15 @@ struct i2c_adapter *i2c_get_adapter(int nr)
 
 	mutex_lock(&core_lock);
 	adapter = idr_find(&i2c_adapter_idr, nr);
-	if (adapter && !try_module_get(adapter->owner))
+	if (!adapter)
+		goto exit;
+
+	if (try_module_get(adapter->owner))
+		get_device(&adapter->dev);
+	else
 		adapter = NULL;
 
+ exit:
 	mutex_unlock(&core_lock);
 	return adapter;
 }
@@ -2423,8 +2429,11 @@ EXPORT_SYMBOL(i2c_get_adapter);
 
 void i2c_put_adapter(struct i2c_adapter *adap)
 {
-	if (adap)
-		module_put(adap->owner);
+	if (!adap)
+		return;
+
+	put_device(&adap->dev);
+	module_put(adap->owner);
 }
 EXPORT_SYMBOL(i2c_put_adapter);