rk_rng_write_ctl
rk_rng_write_ctl(rk_rng, TRNG_RNG_CTL_LEN_256_BIT |
rk_rng_write_ctl(rk_rng, 0, TRNG_RNG_CTL_MASK);
rk_rng_write_ctl(rk_rng, TRNG_RNG_CTL_START, TRNG_RNG_CTL_START);