SR_PRIV int serial_open(struct sr_serial_dev_inst *serial, int flags);
SR_PRIV int serial_close(struct sr_serial_dev_inst *serial);
SR_PRIV int serial_flush(struct sr_serial_dev_inst *serial);
+SR_PRIV int serial_drain(struct sr_serial_dev_inst *serial);
SR_PRIV int serial_write_blocking(struct sr_serial_dev_inst *serial,
const void *buf, size_t count, unsigned int timeout_ms);
SR_PRIV int serial_write_nonblocking(struct sr_serial_dev_inst *serial,