/* Read a single byte from the transport channel. */
static int read_byte(struct gnss_driver_t *self_p, char *byte_p)
/* Read a single byte from the transport channel. */
static int read_byte(struct gnss_driver_t *self_p, char *byte_p)
{
    int res;
    res = chan_read(self_p->chin_p,
                    byte_p,
                    sizeof(*byte_p));
    if (res == 0) {
        res = -EIO;
    }
    return (res);
}