Return parameter as i2c_adapter or null
struct i2c_adapter * i2c_verify_adapter(struct device * dev);
dev
device, probably from some driver model iterator
When traversing the driver model tree, perhaps using driver model iterators like @device_for_each_child, you can't assume very much about the nodes you find. Use this function to avoid oopses caused by wrongly treating some non-I2C device as an i2c_adapter.