REG_BCRM_GAIN_RW
ret = alvium_read(alvium, REG_BCRM_GAIN_RW, &gain, NULL);
ret = alvium_write_hshake(alvium, REG_BCRM_GAIN_RW, (u64)gain);
alvium_read(alvium, REG_BCRM_GAIN_RW, &dft_gain, &ret);