Man page 9 : input_free_device

input_free_device - free memory occupied by input_dev structure

void input_free_device(struct input_dev *  dev );

dev
    input device to free

This function should only be used if input_register_device was not called yet or if it failed. Once device was registered use input_unregister_device and memory will be freed once last reference to the device is dropped.

Device should be allocated by input_allocate_device.

If there are references to the input device then memory will not be freed until last reference is dropped.