Man page 9 : sparse_keymap_free

sparse_keymap_free - free memory allocated for sparse keymap

void sparse_keymap_free(struct input_dev *  dev );

dev
    Input device using sparse keymap

This function is used to free memory allocated by sparse keymap in an input device that was set up by sparse_keymap_setup.

It is safe to cal this function while input device is still registered (however the drivers should care not to try to use freed keymap and thus have to shut off interrups/polling before freeing the keymap).