SR_PRIV int hcs_send_cmd(struct sr_serial_dev_inst *serial, const char *cmd, ...);
SR_PRIV int hcs_receive_data(int fd, int revents, void *cb_data);
SR_PRIV int hcs_send_cmd(struct sr_serial_dev_inst *serial, const char *cmd, ...);
SR_PRIV int hcs_receive_data(int fd, int revents, void *cb_data);