device_add_child
sc->msk_devs[MSK_PORT_A] = device_add_child(dev, "msk", -1);
sc->msk_devs[MSK_PORT_B] = device_add_child(dev, "msk", -1);
sc->sk_devs[SK_PORT_A] = device_add_child(dev, "sk", -1);
sc->sk_devs[SK_PORT_B] = device_add_child(dev, "sk", -1);
device_t device_add_child(device_t dev, const char* name, int unit);
phy = device_add_child(dev, name, unit);
*miibus = device_add_child(dev, "miibus", -1);
phy = device_add_child(*miibus, NULL, -1);
device_t root = device_add_child(NULL, NULL, 0);
device_t child = device_add_child(root, NULL, 0);