IP22ZILOG_FLAG_TX_ACTIVE
up->flags &= ~IP22ZILOG_FLAG_TX_ACTIVE;
up->flags |= IP22ZILOG_FLAG_TX_ACTIVE;
up->flags |= IP22ZILOG_FLAG_TX_ACTIVE;
up->flags |= IP22ZILOG_FLAG_TX_ACTIVE;
#define ZS_TX_ACTIVE(UP) ((UP)->flags & IP22ZILOG_FLAG_TX_ACTIVE)