ATA_DEV1
tf->device | ATA_DEV1 : tf->device & ~ATA_DEV1;
tmp = ATA_DEVICE_OBS | ATA_DEV1;
tmp |= ATA_DEV1;
tmp = ATA_DEVICE_OBS | ATA_DEV1;
dev_reg = ATA_DEVICE_OBS | ATA_DEV1;
dev_reg = ATA_DEVICE_OBS | ATA_DEV1;
tf->device = ATA_DEVICE_OBS | ATA_DEV1;