Merged from sys/dev/sio/sio.c revisions from 1.405 to 1.414.

2 files changed, 274 insertions, 308 deletions

diff --git a/sys/pc98/cbus/sio.c b/sys/pc98/cbus/sio.c
index 2ca08cb..3c4b165 100644
--- a/sys/pc98/cbus/sio.c
+++ b/sys/pc98/cbus/sio.c
@@ -182,20 +182,20 @@
 #define	COM_ISMULTIPORT(flags)	(0)
 #endif /* COM_MULTIPORT */
 
+#define	COM_C_IIR_TXRDYBUG	0x80000
 #define	COM_CONSOLE(flags)	((flags) & 0x10)
+#define	COM_DEBUGGER(flags)	((flags) & 0x80)
+#define	COM_FIFOSIZE(flags)	(((flags) & 0xff000000) >> 24)
 #define	COM_FORCECONSOLE(flags)	((flags) & 0x20)
+#define	COM_IIR_TXRDYBUG(flags)	((flags) & COM_C_IIR_TXRDYBUG)
 #define	COM_LLCONSOLE(flags)	((flags) & 0x40)
-#define	COM_DEBUGGER(flags)	((flags) & 0x80)
 #define	COM_LOSESOUTINTS(flags)	((flags) & 0x08)
-#define	COM_NOFIFO(flags)		((flags) & 0x02)
+#define	COM_NOFIFO(flags)	((flags) & 0x02)
+#define	COM_NOPROBE(flags)	((flags) & 0x40000)
+#define	COM_NOSCR(flags)	((flags) & 0x100000)
 #define	COM_PPSCTS(flags)	((flags) & 0x10000)
-#define COM_ST16650A(flags)	((flags) & 0x20000)
-#define COM_C_NOPROBE		(0x40000)
-#define COM_NOPROBE(flags)	((flags) & COM_C_NOPROBE)
-#define COM_C_IIR_TXRDYBUG	(0x80000)
-#define COM_IIR_TXRDYBUG(flags)	((flags) & COM_C_IIR_TXRDYBUG)
-#define COM_NOSCR(flags)	((flags) & 0x100000)
-#define	COM_FIFOSIZE(flags)	(((flags) & 0xff000000) >> 24)
+#define	COM_ST16650A(flags)	((flags) & 0x20000)
+#define	COM_TI16754(flags)	((flags) & 0x200000)
 
 #define	sio_getreg(com, off) \
 	(bus_space_read_1((com)->bst, (com)->bsh, (off)))
@@ -254,7 +254,6 @@ struct lbq {
 
 /* com device structure */
 struct com_s {
-	u_int	flags;		/* Copy isa device flags */
 	u_char	state;		/* miscellaneous flag bits */
 	bool_t  active_out;	/* nonzero if the callout device is open */
 	u_char	cfcr_image;	/* copy of value written to CFCR */
@@ -264,7 +263,6 @@ struct com_s {
 	u_char	extra_state;	/* more flag bits, separate for order trick */
 	u_char	fifo_image;	/* copy of value written to FIFO */
 	bool_t	hasfifo;	/* nonzero for 16550 UARTs */
-	bool_t	st16650a;	/* Is a Startech 16650A or RTS/CTS compat */
 	bool_t	loses_outints;	/* nonzero if device loses output interrupts */
 	u_char	mcr_image;	/* copy of value written to MCR */
 #ifdef COM_MULTIPORT
@@ -274,8 +272,10 @@ struct com_s {
 	bool_t  gone;		/* hardware disappeared */
 	bool_t	poll;		/* nonzero if polling is required */
 	bool_t	poll_output;	/* nonzero if polling for output is required */
+	bool_t	st16650a;	/* nonzero if Startech 16650A compatible */
 	int	unit;		/* unit	number */
 	int	dtr_wait;	/* time to hold DTR down on close (* 1/hz) */
+	u_int	flags;		/* copy of device flags */
 	u_int	tx_fifo_size;
 	u_int	wopeners;	/* # processes waiting for DCD in open() */
 
@@ -325,11 +325,11 @@ struct com_s {
 #ifdef COM_ESP
 	Port_t	esp_port;
 #endif
+	Port_t	int_ctl_port;
 	Port_t	int_id_port;
 	Port_t	modem_ctl_port;
 	Port_t	line_status_port;
 	Port_t	modem_status_port;
-	Port_t	intr_ctl_port;	/* Ports of IIR register */
 
 	struct tty	*tp;	/* cross reference */
 
@@ -784,7 +784,7 @@ siodetach(dev)
 		device_printf(dev, "NULL com in siounload\n");
 		return (0);
 	}
-	com->gone = 1;
+	com->gone = TRUE;
 	for (i = 0 ; i < 6; i++)
 		destroy_dev(com->devs[i]);
 	if (com->irqres) {
@@ -1172,7 +1172,10 @@ sioprobe(dev, xrid, rclk, noprobe)
 	 * it's unlikely to do more than allow the null byte out.
 	 */
 	sio_setreg(com, com_data, 0);
-	DELAY((1 + 2) * 1000000 / (SIO_TEST_SPEED / 10));
+	if (iobase == siocniobase)
+		DELAY((1 + 2) * 1000000 / (comdefaultrate / 10));
+	else
+		DELAY((1 + 2) * 1000000 / (SIO_TEST_SPEED / 10));
 
 	/*
 	 * Turn off loopback mode so that the interrupt gate works again
@@ -1192,30 +1195,37 @@ sioprobe(dev, xrid, rclk, noprobe)
 	sio_setreg(com, com_cfcr, CFCR_8BITS);
 
 	/*
-	 * Some pcmcia cards have the "TXRDY bug", so we check everyone
-	 * for IIR_TXRDY implementation ( Palido 321s, DC-1S... )
+	 * Some PCMCIA cards (Palido 321s, DC-1S, ...) have the "TXRDY bug",
+	 * so we probe for a buggy IIR_TXRDY implementation even in the
+	 * noprobe case.  We don't probe for it in the !noprobe case because
+	 * noprobe is always set for PCMCIA cards and the problem is not
+	 * known to affect any other cards.
 	 */
 	if (noprobe) {
-		/* Reading IIR register twice */
+		/* Read IIR a few times. */
 		for (fn = 0; fn < 2; fn ++) {
 			DELAY(10000);
 			failures[6] = sio_getreg(com, com_iir);
 		}
-		/* Check IIR_TXRDY clear ? */
+
+		/* IIR_TXRDY should be clear.  Is it? */
 		result = 0;
 		if (failures[6] & IIR_TXRDY) {
-			/* No, Double check with clearing IER */
+			/*
+			 * No.  We seem to have the bug.  Does our fix for
+			 * it work?
+			 */
 			sio_setreg(com, com_ier, 0);
 			if (sio_getreg(com, com_iir) & IIR_NOPEND) {
-				/* Ok. We discovered TXRDY bug! */
+				/* Yes.  We discovered the TXRDY bug! */
 				SET_FLAG(dev, COM_C_IIR_TXRDYBUG);
 			} else {
-				/* Unknown, Just omit this chip.. XXX */
+				/* No.  Just fail.  XXX */
 				result = ENXIO;
 				sio_setreg(com, com_mcr, 0);
 			}
 		} else {
-			/* OK. this is well-known guys */
+			/* Yes.  No bug. */
 			CLR_FLAG(dev, COM_C_IIR_TXRDYBUG);
 		}
 		sio_setreg(com, com_ier, 0);
@@ -1526,21 +1536,21 @@ sioattach(dev, xrid, rclk)
 	    bus_addr_t	*iat = if_16550a_type[if_type & 0x0f].iat;
 
 	    com->data_port = iobase + iat[com_data];
+	    com->int_ctl_port = iobase + iat[com_ier];
 	    com->int_id_port = iobase + iat[com_iir];
 	    com->modem_ctl_port = iobase + iat[com_mcr];
 	    com->mcr_image = inb(com->modem_ctl_port);
 	    com->line_status_port = iobase + iat[com_lsr];
 	    com->modem_status_port = iobase + iat[com_msr];
-	    com->intr_ctl_port = iobase + iat[com_ier];
 	}
 #else /* not PC98 */
 	com->data_port = iobase + com_data;
+	com->int_ctl_port = iobase + com_ier;
 	com->int_id_port = iobase + com_iir;
 	com->modem_ctl_port = iobase + com_mcr;
 	com->mcr_image = inb(com->modem_ctl_port);
 	com->line_status_port = iobase + com_lsr;
 	com->modem_status_port = iobase + com_msr;
-	com->intr_ctl_port = iobase + com_ier;
 #endif
 
 #ifdef PC98
@@ -1635,7 +1645,6 @@ sioattach(dev, xrid, rclk)
 #endif /* PC98 */
 	sio_setreg(com, com_fifo, FIFO_ENABLE | FIFO_RX_HIGH);
 	DELAY(100);
-	com->st16650a = 0;
 	switch (inb(com->int_id_port) & IIR_FIFO_MASK) {
 	case FIFO_RX_LOW:
 		printf(" 16450");
@@ -1649,22 +1658,9 @@ sioattach(dev, xrid, rclk)
 	case FIFO_RX_HIGH:
 		if (COM_NOFIFO(flags)) {
 			printf(" 16550A fifo disabled");
-		} else {
-			com->hasfifo = TRUE;
-#ifdef PC98
-			com->tx_fifo_size = 0;	/* XXX flag conflicts. */
-			printf(" 16550A");
-#else
-			if (COM_ST16650A(flags)) {
-				com->st16650a = 1;
-				com->tx_fifo_size = 32;
-				printf(" ST16650A");
-			} else {
-				com->tx_fifo_size = COM_FIFOSIZE(flags);
-				printf(" 16550A");
-			}
-#endif
+			break;
 		}
+		com->hasfifo = TRUE;
 #ifdef PC98
 		if (com->pc98_if_type == COM_IF_RSA98III) {
 			com->tx_fifo_size = 2048;
@@ -1672,8 +1668,20 @@ sioattach(dev, xrid, rclk)
 			outb(com->rsabase + rsa_ier, 0x00);
 			outb(com->rsabase + rsa_frr, 0x00);
 		}
+#else
+		if (COM_ST16650A(flags)) {
+			printf(" ST16650A");
+			com->st16650a = TRUE;
+			com->tx_fifo_size = 32;
+			break;
+		}
+		if (COM_TI16754(flags)) {
+			printf(" TI16754");
+			com->tx_fifo_size = 64;
+			break;
+		}
 #endif
-
+		printf(" 16550A");
 #ifdef COM_ESP
 #ifdef PC98
 		if (com->pc98_if_type == COM_IF_ESP98)
@@ -1683,15 +1691,19 @@ sioattach(dev, xrid, rclk)
 				com->tx_fifo_size = 1024;
 				break;
 			}
+		if (com->esp != NULL)
+			break;
+#endif
+#ifdef PC98
+		com->tx_fifo_size = 16;
+#else
+		com->tx_fifo_size = COM_FIFOSIZE(flags);
+		if (com->tx_fifo_size == 0)
+			com->tx_fifo_size = 16;
+		else
+			printf(" lookalike with %u bytes FIFO",
+			       com->tx_fifo_size);
 #endif
-		if (!com->st16650a) {
-			if (!com->tx_fifo_size)
-				com->tx_fifo_size = 16;
-			else
-				printf(" lookalike with %d bytes FIFO",
-				    com->tx_fifo_size);
-		}
-
 		break;
 	}
 	
@@ -1707,7 +1719,7 @@ sioattach(dev, xrid, rclk)
 #endif
 
 #ifdef COM_ESP
-	if (com->esp) {
+	if (com->esp != NULL) {
 		/*
 		 * Set 16550 compatibility mode.
 		 * We don't use the ESP_MODE_SCALE bit to increase the
@@ -1784,7 +1796,7 @@ determined_type: ;
 	if (unit == comconsole)
 		printf(", console");
 	if (COM_IIR_TXRDYBUG(flags))
-		printf(" with a bogus IIR_TXRDY register");
+		printf(" with a buggy IIR_TXRDY implementation");
 	printf("\n");
 
 	if (sio_fast_ih == NULL) {
@@ -2019,17 +2031,13 @@ open_top:
 		(void) inb(com->data_port);
 		com->prev_modem_status = com->last_modem_status
 		    = inb(com->modem_status_port);
-		if (COM_IIR_TXRDYBUG(com->flags)) {
-			outb(com->intr_ctl_port, IER_ERXRDY | IER_ERLS
-						| IER_EMSC);
-		} else {
-			outb(com->intr_ctl_port, IER_ERXRDY | IER_ETXRDY
-						| IER_ERLS | IER_EMSC);
-		}
+		outb(com->int_ctl_port,
+		     IER_ERXRDY | IER_ERLS | IER_EMSC
+		     | (COM_IIR_TXRDYBUG(com->flags) ? 0 : IER_ETXRDY));
 #ifdef PC98
 		if (com->pc98_if_type == COM_IF_RSA98III) {
 			outb(com->rsabase + rsa_ier, 0x1d);
-			outb(com->intr_ctl_port, IER_ERLS | IER_EMSC);
+			outb(com->int_ctl_port, IER_ERLS | IER_EMSC);
 		}
 #endif
 #ifdef PC98
@@ -2327,8 +2335,12 @@ siodivisor(rclk, speed)
 	u_int	divisor;
 	int	error;
 
-	if (speed == 0 || speed > (ULONG_MAX - 1) / 8)
+	if (speed == 0)
+		return (0);
+#if UINT_MAX > (ULONG_MAX - 1) / 8
+	if (speed > (ULONG_MAX - 1) / 8)
 		return (0);
+#endif
 	divisor = (rclk / (8UL * speed) + 1) / 2;
 	if (divisor == 0 || divisor >= 65536)
 		return (0);
@@ -2570,12 +2582,12 @@ static void
 siointr1(com)
 	struct com_s	*com;
 {
+	u_char	int_ctl;
+	u_char	int_ctl_new;
 	u_char	line_status;
 	u_char	modem_status;
 	u_char	*ioptr;
 	u_char	recv_data;
-	u_char	int_ctl;
-	u_char	int_ctl_new;
 
 #ifdef PC98
 	u_char	tmp = 0;
@@ -2583,8 +2595,13 @@ siointr1(com)
 	int	rsa_tx_fifo_size = 0;
 #endif /* PC98 */
 
-	int_ctl = inb(com->intr_ctl_port);
-	int_ctl_new = int_ctl;
+	if (COM_IIR_TXRDYBUG(com->flags)) {
+		int_ctl = inb(com->int_ctl_port);
+		int_ctl_new = int_ctl;
+	} else {
+		int_ctl = 0;
+		int_ctl_new = 0;
+	}
 
 	while (!com->gone) {
 #ifdef PC98
@@ -2854,9 +2871,8 @@ cont:
 				com_int_Tx_enable(com);
 #endif
 			com->obufq.l_head = ioptr;
-			if (COM_IIR_TXRDYBUG(com->flags)) {
+			if (COM_IIR_TXRDYBUG(com->flags))
 				int_ctl_new = int_ctl | IER_ETXRDY;
-			}
 			if (ioptr >= com->obufq.l_tail) {
 				struct lbq	*qp;
 
@@ -2869,9 +2885,9 @@ cont:
 					com->obufq.l_next = qp;
 				} else {
 					/* output just completed */
-					if (COM_IIR_TXRDYBUG(com->flags)) {
-						int_ctl_new = int_ctl & ~IER_ETXRDY;
-					}
+					if (COM_IIR_TXRDYBUG(com->flags))
+						int_ctl_new = int_ctl
+							      & ~IER_ETXRDY;
 					com->state &= ~CS_BUSY;
 #if defined(PC98)
 					if (IS_8251(com->pc98_if_type) &&
@@ -2886,16 +2902,21 @@ cont:
 					swi_sched(sio_fast_ih, 0);
 				}
 			}
-			if (COM_IIR_TXRDYBUG(com->flags) && (int_ctl != int_ctl_new)) {
 #ifdef PC98
+			if (COM_IIR_TXRDYBUG(com->flags)
+			    && int_ctl != int_ctl_new) {
 				if (com->pc98_if_type == COM_IF_RSA98III) {
 				    int_ctl_new &= ~(IER_ETXRDY | IER_ERXRDY);
-				    outb(com->intr_ctl_port, int_ctl_new);
+				    outb(com->int_ctl_port, int_ctl_new);
 				    outb(com->rsabase + rsa_ier, 0x1d);
 				} else
-#endif
-				outb(com->intr_ctl_port, int_ctl_new);
+				    outb(com->int_ctl_port, int_ctl_new);
 			}
+#else
+			if (COM_IIR_TXRDYBUG(com->flags)
+			    && int_ctl != int_ctl_new)
+				outb(com->int_ctl_port, int_ctl_new);
+#endif
 		}
 #ifdef PC98
 		else if (line_status & LSR_TXRDY) {
@@ -3235,6 +3256,7 @@ comparam(tp, t)
 	u_int		divisor;
 	u_char		dlbh;
 	u_char		dlbl;
+	u_char		efr_flowbits;
 	int		s;
 	int		unit;
 #ifdef PC98
@@ -3254,20 +3276,12 @@ comparam(tp, t)
 			return (EINVAL);
 	} else {
 #endif
-	/* do historical conversions */
-	if (t->c_ispeed == 0)
-		t->c_ispeed = t->c_ospeed;
-
 	/* check requested parameters */
-	if (t->c_ospeed == 0)
-		divisor = 0;
-	else {
-		if (t->c_ispeed != t->c_ospeed)
-			return (EINVAL);
-		divisor = siodivisor(com->rclk, t->c_ispeed);
-		if (divisor == 0)
-			return (EINVAL);
-	}
+	if (t->c_ispeed != (t->c_ospeed != 0 ? t->c_ospeed : tp->t_ospeed))
+		return (EINVAL);
+	divisor = siodivisor(com->rclk, t->c_ispeed);
+	if (divisor == 0)
+		return (EINVAL);
 #ifdef PC98
 	}
 #endif
@@ -3276,13 +3290,13 @@ comparam(tp, t)
 	s = spltty();
 #ifdef PC98
 	if (IS_8251(com->pc98_if_type)) {
-		if (divisor == 0)
+		if (t->c_ospeed == 0)
 			com_tiocm_bic(com, TIOCM_DTR|TIOCM_RTS|TIOCM_LE);
 		else
 			com_tiocm_bis(com, TIOCM_DTR|TIOCM_RTS|TIOCM_LE);
 	} else
 #endif
-	if (divisor == 0)
+	if (t->c_ospeed == 0)
 		(void)commctl(com, TIOCM_DTR, DMBIC);	/* hang up line */
 	else
 		(void)commctl(com, TIOCM_DTR, DMBIS);
@@ -3312,7 +3326,7 @@ comparam(tp, t)
 	if (cflag & CSTOPB)
 		cfcr |= CFCR_STOPB;
 
-	if (com->hasfifo && divisor != 0) {
+	if (com->hasfifo) {
 		/*
 		 * Use a fifo trigger level low enough so that the input
 		 * latency from the fifo is less than about 16 msec and
@@ -3321,13 +3335,13 @@ comparam(tp, t)
 		 * protocols shouldn't expect anything better since modem
 		 * latencies are larger.
 		 *
-		 * We have to set the FIFO trigger point such that we
-		 * don't overflow it accidently if a serial interrupt
-		 * is delayed.  At high speeds, FIFO_RX_HIGH does not
-		 * leave enough slots free.
+		 * The fifo trigger level cannot be set at RX_HIGH for high
+		 * speed connections without further work on reducing 
+		 * interrupt disablement times in other parts of the system,
+		 * without producing silo overflow errors.
 		 */
 		com->fifo_image = com->unit == siotsunit ? 0
-				  : t->c_ospeed <= 4800
+				  : t->c_ispeed <= 4800
 				  ? FIFO_ENABLE : FIFO_ENABLE | FIFO_RX_MEDH;
 #ifdef COM_ESP
 		/*
@@ -3356,39 +3370,27 @@ comparam(tp, t)
 		com_cflag_and_speed_set(com, cflag, t->c_ospeed);
 	else {
 #endif
-	if (divisor != 0) {
-		sio_setreg(com, com_cfcr, cfcr | CFCR_DLAB);
-		/*
-		 * Only set the divisor registers if they would change,
-		 * since on some 16550 incompatibles (UMC8669F), setting
-		 * them while input is arriving them loses sync until
-		 * data stops arriving.
-		 */
-		dlbl = divisor & 0xFF;
-		if (sio_getreg(com, com_dlbl) != dlbl)
-			sio_setreg(com, com_dlbl, dlbl);
-		dlbh = divisor >> 8;
-		if (sio_getreg(com, com_dlbh) != dlbh)
-			sio_setreg(com, com_dlbh, dlbh);
-	}
-
-	sio_setreg(com, com_cfcr, com->cfcr_image = cfcr);
+	sio_setreg(com, com_cfcr, cfcr | CFCR_DLAB);
+	/*
+	 * Only set the divisor registers if they would change, since on
+	 * some 16550 incompatibles (UMC8669F), setting them while input
+	 * is arriving loses sync until data stops arriving.
+	 */
+	dlbl = divisor & 0xFF;
+	if (sio_getreg(com, com_dlbl) != dlbl)
+		sio_setreg(com, com_dlbl, dlbl);
+	dlbh = divisor >> 8;
+	if (sio_getreg(com, com_dlbh) != dlbh)
+		sio_setreg(com, com_dlbh, dlbh);
 #ifdef PC98
 	}
 #endif
 
-	if (!(tp->t_state & TS_TTSTOP))
-		com->state |= CS_TTGO;
+	efr_flowbits = 0;
 
 	if (cflag & CRTS_IFLOW) {
-#ifndef PC98
-		if (com->st16650a) {
-			sio_setreg(com, com_cfcr, 0xbf);
-			sio_setreg(com, com_fifo,
-				   sio_getreg(com, com_fifo) | 0x40);
-		}
-#endif
 		com->state |= CS_RTS_IFLOW;
+		efr_flowbits |= EFR_AUTORTS;
 		/*
 		 * If CS_RTS_IFLOW just changed from off to on, the change
 		 * needs to be propagated to MCR_RTS.  This isn't urgent,
@@ -3408,15 +3410,9 @@ comparam(tp, t)
 			outb(com->modem_ctl_port, com->mcr_image |= MCR_RTS);
 #else
 		outb(com->modem_ctl_port, com->mcr_image |= MCR_RTS);
-		if (com->st16650a) {
-			sio_setreg(com, com_cfcr, 0xbf);
-			sio_setreg(com, com_fifo,
-				   sio_getreg(com, com_fifo) & ~0x40);
-		}
 #endif
 	}
 
-
 	/*
 	 * Set up state to handle output flow control.
 	 * XXX - worth handling MDMBUF (DCD) flow control at the lowest level?
@@ -3432,49 +3428,35 @@ comparam(tp, t)
 #endif
 	if (cflag & CCTS_OFLOW) {
 		com->state |= CS_CTS_OFLOW;
+		efr_flowbits |= EFR_AUTOCTS;
 #ifdef PC98
 		if (IS_8251(com->pc98_if_type)) {
 			if (!(pc98_get_modem_status(com) & TIOCM_CTS))
 				com->state &= ~CS_ODEVREADY;
-		} else {
-			if (com->pc98_if_type == COM_IF_RSA98III) {
-				/* Set automatic flow control mode */
-				outb(com->rsabase + rsa_msr, param | 0x08);
-			} else
+		} else if (com->pc98_if_type == COM_IF_RSA98III) {
+			/* Set automatic flow control mode */
+			outb(com->rsabase + rsa_msr, param | 0x08);
+		} else
 #endif
 		if (!(com->last_modem_status & MSR_CTS))
 			com->state &= ~CS_ODEVREADY;
-#ifdef PC98
-		}
-#else
-		if (com->st16650a) {
-			sio_setreg(com, com_cfcr, 0xbf);
-			sio_setreg(com, com_fifo,
-				   sio_getreg(com, com_fifo) | 0x80);
-		}
-	} else {
-		if (com->st16650a) {
-			sio_setreg(com, com_cfcr, 0xbf);
-			sio_setreg(com, com_fifo,
-				   sio_getreg(com, com_fifo) & ~0x80);
-		}
-#endif
 	}
 
 #ifdef PC98
 	if (!IS_8251(com->pc98_if_type))
+		sio_setreg(com, com_cfcr, com->cfcr_image = cfcr);
+#else
+	if (com->st16650a) {
+		sio_setreg(com, com_lcr, LCR_EFR_ENABLE);
+		sio_setreg(com, com_efr,
+			   (sio_getreg(com, com_efr)
+			    & ~(EFR_AUTOCTS | EFR_AUTORTS)) | efr_flowbits);
+	}
+	sio_setreg(com, com_cfcr, com->cfcr_image = cfcr);
 #endif
-	sio_setreg(com, com_cfcr, com->cfcr_image);
 
 	/* XXX shouldn't call functions while intrs are disabled. */
 	disc_optim(tp, t, com);
-	/*
-	 * Recover from fiddling with CS_TTGO.  We used to call siointr1()
-	 * unconditionally, but that defeated the careful discarding of
-	 * stale input in sioopen().
-	 */
-	if (com->state >= (CS_BUSY | CS_TTGO))
-		siointr1(com);
 
 	mtx_unlock_spin(&sio_lock);
 	splx(s);
@@ -4158,6 +4140,7 @@ siocnprobe(cp)
 
 	for (unit = 0; unit < 16; unit++) { /* XXX need to know how many */
 		int flags;
+
 		if (resource_disabled("sio", unit))
 			continue;
 		if (resource_int_value("sio", unit, "flags", &flags))
diff --git a/sys/pc98/pc98/sio.c b/sys/pc98/pc98/sio.c
index 2ca08cb..3c4b165 100644
--- a/sys/pc98/pc98/sio.c
+++ b/sys/pc98/pc98/sio.c
@@ -182,20 +182,20 @@
 #define	COM_ISMULTIPORT(flags)	(0)
 #endif /* COM_MULTIPORT */
 
+#define	COM_C_IIR_TXRDYBUG	0x80000
 #define	COM_CONSOLE(flags)	((flags) & 0x10)
+#define	COM_DEBUGGER(flags)	((flags) & 0x80)
+#define	COM_FIFOSIZE(flags)	(((flags) & 0xff000000) >> 24)
 #define	COM_FORCECONSOLE(flags)	((flags) & 0x20)
+#define	COM_IIR_TXRDYBUG(flags)	((flags) & COM_C_IIR_TXRDYBUG)
 #define	COM_LLCONSOLE(flags)	((flags) & 0x40)
-#define	COM_DEBUGGER(flags)	((flags) & 0x80)
 #define	COM_LOSESOUTINTS(flags)	((flags) & 0x08)
-#define	COM_NOFIFO(flags)		((flags) & 0x02)
+#define	COM_NOFIFO(flags)	((flags) & 0x02)
+#define	COM_NOPROBE(flags)	((flags) & 0x40000)
+#define	COM_NOSCR(flags)	((flags) & 0x100000)
 #define	COM_PPSCTS(flags)	((flags) & 0x10000)
-#define COM_ST16650A(flags)	((flags) & 0x20000)
-#define COM_C_NOPROBE		(0x40000)
-#define COM_NOPROBE(flags)	((flags) & COM_C_NOPROBE)
-#define COM_C_IIR_TXRDYBUG	(0x80000)
-#define COM_IIR_TXRDYBUG(flags)	((flags) & COM_C_IIR_TXRDYBUG)
-#define COM_NOSCR(flags)	((flags) & 0x100000)
-#define	COM_FIFOSIZE(flags)	(((flags) & 0xff000000) >> 24)
+#define	COM_ST16650A(flags)	((flags) & 0x20000)
+#define	COM_TI16754(flags)	((flags) & 0x200000)
 
 #define	sio_getreg(com, off) \
 	(bus_space_read_1((com)->bst, (com)->bsh, (off)))
@@ -254,7 +254,6 @@ struct lbq {
 
 /* com device structure */
 struct com_s {
-	u_int	flags;		/* Copy isa device flags */
 	u_char	state;		/* miscellaneous flag bits */
 	bool_t  active_out;	/* nonzero if the callout device is open */
 	u_char	cfcr_image;	/* copy of value written to CFCR */
@@ -264,7 +263,6 @@ struct com_s {
 	u_char	extra_state;	/* more flag bits, separate for order trick */
 	u_char	fifo_image;	/* copy of value written to FIFO */
 	bool_t	hasfifo;	/* nonzero for 16550 UARTs */
-	bool_t	st16650a;	/* Is a Startech 16650A or RTS/CTS compat */
 	bool_t	loses_outints;	/* nonzero if device loses output interrupts */
 	u_char	mcr_image;	/* copy of value written to MCR */
 #ifdef COM_MULTIPORT
@@ -274,8 +272,10 @@ struct com_s {
 	bool_t  gone;		/* hardware disappeared */
 	bool_t	poll;		/* nonzero if polling is required */
 	bool_t	poll_output;	/* nonzero if polling for output is required */
+	bool_t	st16650a;	/* nonzero if Startech 16650A compatible */
 	int	unit;		/* unit	number */
 	int	dtr_wait;	/* time to hold DTR down on close (* 1/hz) */
+	u_int	flags;		/* copy of device flags */
 	u_int	tx_fifo_size;
 	u_int	wopeners;	/* # processes waiting for DCD in open() */
 
@@ -325,11 +325,11 @@ struct com_s {
 #ifdef COM_ESP
 	Port_t	esp_port;
 #endif
+	Port_t	int_ctl_port;
 	Port_t	int_id_port;
 	Port_t	modem_ctl_port;
 	Port_t	line_status_port;
 	Port_t	modem_status_port;
-	Port_t	intr_ctl_port;	/* Ports of IIR register */
 
 	struct tty	*tp;	/* cross reference */
 
@@ -784,7 +784,7 @@ siodetach(dev)
 		device_printf(dev, "NULL com in siounload\n");
 		return (0);
 	}
-	com->gone = 1;
+	com->gone = TRUE;
 	for (i = 0 ; i < 6; i++)
 		destroy_dev(com->devs[i]);
 	if (com->irqres) {
@@ -1172,7 +1172,10 @@ sioprobe(dev, xrid, rclk, noprobe)
 	 * it's unlikely to do more than allow the null byte out.
 	 */
 	sio_setreg(com, com_data, 0);
-	DELAY((1 + 2) * 1000000 / (SIO_TEST_SPEED / 10));
+	if (iobase == siocniobase)
+		DELAY((1 + 2) * 1000000 / (comdefaultrate / 10));
+	else
+		DELAY((1 + 2) * 1000000 / (SIO_TEST_SPEED / 10));
 
 	/*
 	 * Turn off loopback mode so that the interrupt gate works again
@@ -1192,30 +1195,37 @@ sioprobe(dev, xrid, rclk, noprobe)
 	sio_setreg(com, com_cfcr, CFCR_8BITS);
 
 	/*
-	 * Some pcmcia cards have the "TXRDY bug", so we check everyone
-	 * for IIR_TXRDY implementation ( Palido 321s, DC-1S... )
+	 * Some PCMCIA cards (Palido 321s, DC-1S, ...) have the "TXRDY bug",
+	 * so we probe for a buggy IIR_TXRDY implementation even in the
+	 * noprobe case.  We don't probe for it in the !noprobe case because
+	 * noprobe is always set for PCMCIA cards and the problem is not
+	 * known to affect any other cards.
 	 */
 	if (noprobe) {
-		/* Reading IIR register twice */
+		/* Read IIR a few times. */
 		for (fn = 0; fn < 2; fn ++) {
 			DELAY(10000);
 			failures[6] = sio_getreg(com, com_iir);
 		}
-		/* Check IIR_TXRDY clear ? */
+
+		/* IIR_TXRDY should be clear.  Is it? */
 		result = 0;
 		if (failures[6] & IIR_TXRDY) {
-			/* No, Double check with clearing IER */
+			/*
+			 * No.  We seem to have the bug.  Does our fix for
+			 * it work?
+			 */
 			sio_setreg(com, com_ier, 0);
 			if (sio_getreg(com, com_iir) & IIR_NOPEND) {
-				/* Ok. We discovered TXRDY bug! */
+				/* Yes.  We discovered the TXRDY bug! */
 				SET_FLAG(dev, COM_C_IIR_TXRDYBUG);
 			} else {
-				/* Unknown, Just omit this chip.. XXX */
+				/* No.  Just fail.  XXX */
 				result = ENXIO;
 				sio_setreg(com, com_mcr, 0);
 			}
 		} else {
-			/* OK. this is well-known guys */
+			/* Yes.  No bug. */
 			CLR_FLAG(dev, COM_C_IIR_TXRDYBUG);
 		}
 		sio_setreg(com, com_ier, 0);
@@ -1526,21 +1536,21 @@ sioattach(dev, xrid, rclk)
 	    bus_addr_t	*iat = if_16550a_type[if_type & 0x0f].iat;
 
 	    com->data_port = iobase + iat[com_data];
+	    com->int_ctl_port = iobase + iat[com_ier];
 	    com->int_id_port = iobase + iat[com_iir];
 	    com->modem_ctl_port = iobase + iat[com_mcr];
 	    com->mcr_image = inb(com->modem_ctl_port);
 	    com->line_status_port = iobase + iat[com_lsr];
 	    com->modem_status_port = iobase + iat[com_msr];
-	    com->intr_ctl_port = iobase + iat[com_ier];
 	}
 #else /* not PC98 */
 	com->data_port = iobase + com_data;
+	com->int_ctl_port = iobase + com_ier;
 	com->int_id_port = iobase + com_iir;
 	com->modem_ctl_port = iobase + com_mcr;
 	com->mcr_image = inb(com->modem_ctl_port);
 	com->line_status_port = iobase + com_lsr;
 	com->modem_status_port = iobase + com_msr;
-	com->intr_ctl_port = iobase + com_ier;
 #endif
 
 #ifdef PC98
@@ -1635,7 +1645,6 @@ sioattach(dev, xrid, rclk)
 #endif /* PC98 */
 	sio_setreg(com, com_fifo, FIFO_ENABLE | FIFO_RX_HIGH);
 	DELAY(100);
-	com->st16650a = 0;
 	switch (inb(com->int_id_port) & IIR_FIFO_MASK) {
 	case FIFO_RX_LOW:
 		printf(" 16450");
@@ -1649,22 +1658,9 @@ sioattach(dev, xrid, rclk)
 	case FIFO_RX_HIGH:
 		if (COM_NOFIFO(flags)) {
 			printf(" 16550A fifo disabled");
-		} else {
-			com->hasfifo = TRUE;
-#ifdef PC98
-			com->tx_fifo_size = 0;	/* XXX flag conflicts. */
-			printf(" 16550A");
-#else
-			if (COM_ST16650A(flags)) {
-				com->st16650a = 1;
-				com->tx_fifo_size = 32;
-				printf(" ST16650A");
-			} else {
-				com->tx_fifo_size = COM_FIFOSIZE(flags);
-				printf(" 16550A");
-			}
-#endif
+			break;
 		}
+		com->hasfifo = TRUE;
 #ifdef PC98
 		if (com->pc98_if_type == COM_IF_RSA98III) {
 			com->tx_fifo_size = 2048;
@@ -1672,8 +1668,20 @@ sioattach(dev, xrid, rclk)
 			outb(com->rsabase + rsa_ier, 0x00);
 			outb(com->rsabase + rsa_frr, 0x00);
 		}
+#else
+		if (COM_ST16650A(flags)) {
+			printf(" ST16650A");
+			com->st16650a = TRUE;
+			com->tx_fifo_size = 32;
+			break;
+		}
+		if (COM_TI16754(flags)) {
+			printf(" TI16754");
+			com->tx_fifo_size = 64;
+			break;
+		}
 #endif
-
+		printf(" 16550A");
 #ifdef COM_ESP
 #ifdef PC98
 		if (com->pc98_if_type == COM_IF_ESP98)
@@ -1683,15 +1691,19 @@ sioattach(dev, xrid, rclk)
 				com->tx_fifo_size = 1024;
 				break;
 			}
+		if (com->esp != NULL)
+			break;
+#endif
+#ifdef PC98
+		com->tx_fifo_size = 16;
+#else
+		com->tx_fifo_size = COM_FIFOSIZE(flags);
+		if (com->tx_fifo_size == 0)
+			com->tx_fifo_size = 16;
+		else
+			printf(" lookalike with %u bytes FIFO",
+			       com->tx_fifo_size);
 #endif
-		if (!com->st16650a) {
-			if (!com->tx_fifo_size)
-				com->tx_fifo_size = 16;
-			else
-				printf(" lookalike with %d bytes FIFO",
-				    com->tx_fifo_size);
-		}
-
 		break;
 	}
 	
@@ -1707,7 +1719,7 @@ sioattach(dev, xrid, rclk)
 #endif
 
 #ifdef COM_ESP
-	if (com->esp) {
+	if (com->esp != NULL) {
 		/*
 		 * Set 16550 compatibility mode.
 		 * We don't use the ESP_MODE_SCALE bit to increase the
@@ -1784,7 +1796,7 @@ determined_type: ;
 	if (unit == comconsole)
 		printf(", console");
 	if (COM_IIR_TXRDYBUG(flags))
-		printf(" with a bogus IIR_TXRDY register");
+		printf(" with a buggy IIR_TXRDY implementation");
 	printf("\n");
 
 	if (sio_fast_ih == NULL) {
@@ -2019,17 +2031,13 @@ open_top:
 		(void) inb(com->data_port);
 		com->prev_modem_status = com->last_modem_status
 		    = inb(com->modem_status_port);
-		if (COM_IIR_TXRDYBUG(com->flags)) {
-			outb(com->intr_ctl_port, IER_ERXRDY | IER_ERLS
-						| IER_EMSC);
-		} else {
-			outb(com->intr_ctl_port, IER_ERXRDY | IER_ETXRDY
-						| IER_ERLS | IER_EMSC);
-		}
+		outb(com->int_ctl_port,
+		     IER_ERXRDY | IER_ERLS | IER_EMSC
+		     | (COM_IIR_TXRDYBUG(com->flags) ? 0 : IER_ETXRDY));
 #ifdef PC98
 		if (com->pc98_if_type == COM_IF_RSA98III) {
 			outb(com->rsabase + rsa_ier, 0x1d);
-			outb(com->intr_ctl_port, IER_ERLS | IER_EMSC);
+			outb(com->int_ctl_port, IER_ERLS | IER_EMSC);
 		}
 #endif
 #ifdef PC98
@@ -2327,8 +2335,12 @@ siodivisor(rclk, speed)
 	u_int	divisor;
 	int	error;
 
-	if (speed == 0 || speed > (ULONG_MAX - 1) / 8)
+	if (speed == 0)
+		return (0);
+#if UINT_MAX > (ULONG_MAX - 1) / 8
+	if (speed > (ULONG_MAX - 1) / 8)
 		return (0);
+#endif
 	divisor = (rclk / (8UL * speed) + 1) / 2;
 	if (divisor == 0 || divisor >= 65536)
 		return (0);
@@ -2570,12 +2582,12 @@ static void
 siointr1(com)
 	struct com_s	*com;
 {
+	u_char	int_ctl;
+	u_char	int_ctl_new;
 	u_char	line_status;
 	u_char	modem_status;
 	u_char	*ioptr;
 	u_char	recv_data;
-	u_char	int_ctl;
-	u_char	int_ctl_new;
 
 #ifdef PC98
 	u_char	tmp = 0;
@@ -2583,8 +2595,13 @@ siointr1(com)
 	int	rsa_tx_fifo_size = 0;
 #endif /* PC98 */
 
-	int_ctl = inb(com->intr_ctl_port);
-	int_ctl_new = int_ctl;
+	if (COM_IIR_TXRDYBUG(com->flags)) {
+		int_ctl = inb(com->int_ctl_port);
+		int_ctl_new = int_ctl;
+	} else {
+		int_ctl = 0;
+		int_ctl_new = 0;
+	}
 
 	while (!com->gone) {
 #ifdef PC98
@@ -2854,9 +2871,8 @@ cont:
 				com_int_Tx_enable(com);
 #endif
 			com->obufq.l_head = ioptr;
-			if (COM_IIR_TXRDYBUG(com->flags)) {
+			if (COM_IIR_TXRDYBUG(com->flags))
 				int_ctl_new = int_ctl | IER_ETXRDY;
-			}
 			if (ioptr >= com->obufq.l_tail) {
 				struct lbq	*qp;
 
@@ -2869,9 +2885,9 @@ cont:
 					com->obufq.l_next = qp;
 				} else {
 					/* output just completed */
-					if (COM_IIR_TXRDYBUG(com->flags)) {
-						int_ctl_new = int_ctl & ~IER_ETXRDY;
-					}
+					if (COM_IIR_TXRDYBUG(com->flags))
+						int_ctl_new = int_ctl
+							      & ~IER_ETXRDY;
 					com->state &= ~CS_BUSY;
 #if defined(PC98)
 					if (IS_8251(com->pc98_if_type) &&
@@ -2886,16 +2902,21 @@ cont:
 					swi_sched(sio_fast_ih, 0);
 				}
 			}
-			if (COM_IIR_TXRDYBUG(com->flags) && (int_ctl != int_ctl_new)) {
 #ifdef PC98
+			if (COM_IIR_TXRDYBUG(com->flags)
+			    && int_ctl != int_ctl_new) {
 				if (com->pc98_if_type == COM_IF_RSA98III) {
 				    int_ctl_new &= ~(IER_ETXRDY | IER_ERXRDY);
-				    outb(com->intr_ctl_port, int_ctl_new);
+				    outb(com->int_ctl_port, int_ctl_new);
 				    outb(com->rsabase + rsa_ier, 0x1d);
 				} else
-#endif
-				outb(com->intr_ctl_port, int_ctl_new);
+				    outb(com->int_ctl_port, int_ctl_new);
 			}
+#else
+			if (COM_IIR_TXRDYBUG(com->flags)
+			    && int_ctl != int_ctl_new)
+				outb(com->int_ctl_port, int_ctl_new);
+#endif
 		}
 #ifdef PC98
 		else if (line_status & LSR_TXRDY) {
@@ -3235,6 +3256,7 @@ comparam(tp, t)
 	u_int		divisor;
 	u_char		dlbh;
 	u_char		dlbl;
+	u_char		efr_flowbits;
 	int		s;
 	int		unit;
 #ifdef PC98
@@ -3254,20 +3276,12 @@ comparam(tp, t)
 			return (EINVAL);
 	} else {
 #endif
-	/* do historical conversions */
-	if (t->c_ispeed == 0)
-		t->c_ispeed = t->c_ospeed;
-
 	/* check requested parameters */
-	if (t->c_ospeed == 0)
-		divisor = 0;
-	else {
-		if (t->c_ispeed != t->c_ospeed)
-			return (EINVAL);
-		divisor = siodivisor(com->rclk, t->c_ispeed);
-		if (divisor == 0)
-			return (EINVAL);
-	}
+	if (t->c_ispeed != (t->c_ospeed != 0 ? t->c_ospeed : tp->t_ospeed))
+		return (EINVAL);
+	divisor = siodivisor(com->rclk, t->c_ispeed);
+	if (divisor == 0)
+		return (EINVAL);
 #ifdef PC98
 	}
 #endif
@@ -3276,13 +3290,13 @@ comparam(tp, t)
 	s = spltty();
 #ifdef PC98
 	if (IS_8251(com->pc98_if_type)) {
-		if (divisor == 0)
+		if (t->c_ospeed == 0)
 			com_tiocm_bic(com, TIOCM_DTR|TIOCM_RTS|TIOCM_LE);
 		else
 			com_tiocm_bis(com, TIOCM_DTR|TIOCM_RTS|TIOCM_LE);
 	} else
 #endif
-	if (divisor == 0)
+	if (t->c_ospeed == 0)
 		(void)commctl(com, TIOCM_DTR, DMBIC);	/* hang up line */
 	else
 		(void)commctl(com, TIOCM_DTR, DMBIS);
@@ -3312,7 +3326,7 @@ comparam(tp, t)
 	if (cflag & CSTOPB)
 		cfcr |= CFCR_STOPB;
 
-	if (com->hasfifo && divisor != 0) {
+	if (com->hasfifo) {
 		/*
 		 * Use a fifo trigger level low enough so that the input
 		 * latency from the fifo is less than about 16 msec and
@@ -3321,13 +3335,13 @@ comparam(tp, t)
 		 * protocols shouldn't expect anything better since modem
 		 * latencies are larger.
 		 *
-		 * We have to set the FIFO trigger point such that we
-		 * don't overflow it accidently if a serial interrupt
-		 * is delayed.  At high speeds, FIFO_RX_HIGH does not
-		 * leave enough slots free.
+		 * The fifo trigger level cannot be set at RX_HIGH for high
+		 * speed connections without further work on reducing 
+		 * interrupt disablement times in other parts of the system,
+		 * without producing silo overflow errors.
 		 */
 		com->fifo_image = com->unit == siotsunit ? 0
-				  : t->c_ospeed <= 4800
+				  : t->c_ispeed <= 4800
 				  ? FIFO_ENABLE : FIFO_ENABLE | FIFO_RX_MEDH;
 #ifdef COM_ESP
 		/*
@@ -3356,39 +3370,27 @@ comparam(tp, t)
 		com_cflag_and_speed_set(com, cflag, t->c_ospeed);
 	else {
 #endif
-	if (divisor != 0) {
-		sio_setreg(com, com_cfcr, cfcr | CFCR_DLAB);
-		/*
-		 * Only set the divisor registers if they would change,
-		 * since on some 16550 incompatibles (UMC8669F), setting
-		 * them while input is arriving them loses sync until
-		 * data stops arriving.
-		 */
-		dlbl = divisor & 0xFF;
-		if (sio_getreg(com, com_dlbl) != dlbl)
-			sio_setreg(com, com_dlbl, dlbl);
-		dlbh = divisor >> 8;
-		if (sio_getreg(com, com_dlbh) != dlbh)
-			sio_setreg(com, com_dlbh, dlbh);
-	}
-
-	sio_setreg(com, com_cfcr, com->cfcr_image = cfcr);
+	sio_setreg(com, com_cfcr, cfcr | CFCR_DLAB);
+	/*
+	 * Only set the divisor registers if they would change, since on
+	 * some 16550 incompatibles (UMC8669F), setting them while input
+	 * is arriving loses sync until data stops arriving.
+	 */
+	dlbl = divisor & 0xFF;
+	if (sio_getreg(com, com_dlbl) != dlbl)
+		sio_setreg(com, com_dlbl, dlbl);
+	dlbh = divisor >> 8;
+	if (sio_getreg(com, com_dlbh) != dlbh)
+		sio_setreg(com, com_dlbh, dlbh);
 #ifdef PC98
 	}
 #endif
 
-	if (!(tp->t_state & TS_TTSTOP))
-		com->state |= CS_TTGO;
+	efr_flowbits = 0;
 
 	if (cflag & CRTS_IFLOW) {
-#ifndef PC98
-		if (com->st16650a) {
-			sio_setreg(com, com_cfcr, 0xbf);
-			sio_setreg(com, com_fifo,
-				   sio_getreg(com, com_fifo) | 0x40);
-		}
-#endif
 		com->state |= CS_RTS_IFLOW;
+		efr_flowbits |= EFR_AUTORTS;
 		/*
 		 * If CS_RTS_IFLOW just changed from off to on, the change
 		 * needs to be propagated to MCR_RTS.  This isn't urgent,
@@ -3408,15 +3410,9 @@ comparam(tp, t)
 			outb(com->modem_ctl_port, com->mcr_image |= MCR_RTS);
 #else
 		outb(com->modem_ctl_port, com->mcr_image |= MCR_RTS);
-		if (com->st16650a) {
-			sio_setreg(com, com_cfcr, 0xbf);
-			sio_setreg(com, com_fifo,
-				   sio_getreg(com, com_fifo) & ~0x40);
-		}
 #endif
 	}
 
-
 	/*
 	 * Set up state to handle output flow control.
 	 * XXX - worth handling MDMBUF (DCD) flow control at the lowest level?
@@ -3432,49 +3428,35 @@ comparam(tp, t)
 #endif
 	if (cflag & CCTS_OFLOW) {
 		com->state |= CS_CTS_OFLOW;
+		efr_flowbits |= EFR_AUTOCTS;
 #ifdef PC98
 		if (IS_8251(com->pc98_if_type)) {
 			if (!(pc98_get_modem_status(com) & TIOCM_CTS))
 				com->state &= ~CS_ODEVREADY;
-		} else {
-			if (com->pc98_if_type == COM_IF_RSA98III) {
-				/* Set automatic flow control mode */
-				outb(com->rsabase + rsa_msr, param | 0x08);
-			} else
+		} else if (com->pc98_if_type == COM_IF_RSA98III) {
+			/* Set automatic flow control mode */
+			outb(com->rsabase + rsa_msr, param | 0x08);
+		} else
 #endif
 		if (!(com->last_modem_status & MSR_CTS))
 			com->state &= ~CS_ODEVREADY;
-#ifdef PC98
-		}
-#else
-		if (com->st16650a) {
-			sio_setreg(com, com_cfcr, 0xbf);
-			sio_setreg(com, com_fifo,
-				   sio_getreg(com, com_fifo) | 0x80);
-		}
-	} else {
-		if (com->st16650a) {
-			sio_setreg(com, com_cfcr, 0xbf);
-			sio_setreg(com, com_fifo,
-				   sio_getreg(com, com_fifo) & ~0x80);
-		}
-#endif
 	}
 
 #ifdef PC98
 	if (!IS_8251(com->pc98_if_type))
+		sio_setreg(com, com_cfcr, com->cfcr_image = cfcr);
+#else
+	if (com->st16650a) {
+		sio_setreg(com, com_lcr, LCR_EFR_ENABLE);
+		sio_setreg(com, com_efr,
+			   (sio_getreg(com, com_efr)
+			    & ~(EFR_AUTOCTS | EFR_AUTORTS)) | efr_flowbits);
+	}
+	sio_setreg(com, com_cfcr, com->cfcr_image = cfcr);
 #endif
-	sio_setreg(com, com_cfcr, com->cfcr_image);
 
 	/* XXX shouldn't call functions while intrs are disabled. */
 	disc_optim(tp, t, com);
-	/*
-	 * Recover from fiddling with CS_TTGO.  We used to call siointr1()
-	 * unconditionally, but that defeated the careful discarding of
-	 * stale input in sioopen().
-	 */
-	if (com->state >= (CS_BUSY | CS_TTGO))
-		siointr1(com);
 
 	mtx_unlock_spin(&sio_lock);
 	splx(s);
@@ -4158,6 +4140,7 @@ siocnprobe(cp)
 
 	for (unit = 0; unit < 16; unit++) { /* XXX need to know how many */
 		int flags;
+
 		if (resource_disabled("sio", unit))
 			continue;
 		if (resource_int_value("sio", unit, "flags", &flags))