Convert sparc console code from rcons and pseudo-devices to rasops and wscons.

For most framebuffers it is faster.

Other changes include:
o 24 bit support in tcx(4) for the S24 framebuffer
o accelerated cgsix(4) text console
o new cgtwelve(4) driver for the GS framebuffer
o improved serial driver code
o better keyboard support

The following framebuffers have not been tested but should work: cgfour,
cgeight and cgfourteen

These changes will require XF4 changes, to use Xwsfb instead of Xsun*, to be
commited later today.

Most of the work by me during the LSM and the week after, with code borrowed
from jason@, NetBSD (new serial code), and feedback from mickey@. Work on
pnozz(4) done by millert@

1 files changed, 1637 insertions, 0 deletions

diff --git a/sys/arch/sparc/dev/z8530tty.c b/sys/arch/sparc/dev/z8530tty.c
new file mode 100644
index 00000000000..642fc05cae5
--- /dev/null
+++ b/sys/arch/sparc/dev/z8530tty.c
@@ -0,0 +1,1637 @@
+/*	$OpenBSD: z8530tty.c,v 1.1 2002/08/12 10:44:04 miod Exp $ */
+/*	$NetBSD: z8530tty.c,v 1.13 1996/10/16 20:42:14 gwr Exp $	*/
+
+/*-
+ * Copyright (c) 1993, 1994, 1995, 1996, 1997, 1998, 1999
+ *      Charles M. Hannum.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *      This product includes software developed by Charles M. Hannum.
+ * 4. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/*
+ * Copyright (c) 1994 Gordon W. Ross
+ * Copyright (c) 1992, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * This software was developed by the Computer Systems Engineering group
+ * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
+ * contributed to Berkeley.
+ *
+ * All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ *	This product includes software developed by the University of
+ *	California, Lawrence Berkeley Laboratory.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the University of
+ *	California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ *	@(#)zs.c	8.1 (Berkeley) 7/19/93
+ */
+
+/*
+ * Zilog Z8530 Dual UART driver (tty interface)
+ *
+ * This is the "slave" driver that will be attached to
+ * the "zsc" driver for plain "tty" async. serial lines.
+ *
+ * Credits, history:
+ *
+ * The original version of this code was the sparc/dev/zs.c driver
+ * as distributed with the Berkeley 4.4 Lite release.  Since then,
+ * Gordon Ross reorganized the code into the current parent/child
+ * driver scheme, separating the Sun keyboard and mouse support
+ * into independent child drivers.
+ *
+ * RTS/CTS flow-control support was a collaboration of:
+ *	Gordon Ross <gwr@netbsd.org>,
+ *	Bill Studenmund <wrstuden@loki.stanford.edu>
+ *	Ian Dall <Ian.Dall@dsto.defence.gov.au>
+ *
+ * The driver was massively overhauled in November 1997 by Charles Hannum,
+ * fixing *many* bugs, and substantially improving performance.
+ */
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/proc.h>
+#include <sys/device.h>
+#include <sys/conf.h>
+#include <sys/file.h>
+#include <sys/ioctl.h>
+#include <sys/malloc.h>
+#include <sys/tty.h>
+#include <sys/time.h>
+#include <sys/kernel.h>
+#include <sys/syslog.h>
+
+#include <sparc/dev/z8530reg.h>
+#include <machine/z8530var.h>
+
+#include <dev/cons.h>
+
+#ifdef KGDB
+extern int zs_check_kgdb();
+#endif
+
+/*
+ * Allow the MD var.h to override the default CFLAG so that
+ * console messages during boot come out with correct parity.
+ */
+#ifndef	ZSTTY_DEF_CFLAG
+#define	ZSTTY_DEF_CFLAG	TTYDEF_CFLAG
+#endif
+
+/*
+ * How many input characters we can buffer.
+ * The port-specific var.h may override this.
+ * Note: must be a power of two!
+ */
+#ifndef	ZSTTY_RING_SIZE
+#define	ZSTTY_RING_SIZE	2048
+#endif
+
+/*
+ * Make this an option variable one can patch.
+ * But be warned:  this must be a power of 2!
+ */
+u_int zstty_rbuf_size = ZSTTY_RING_SIZE;
+
+/* Stop input when 3/4 of the ring is full; restart when only 1/4 is full. */
+u_int zstty_rbuf_hiwat = (ZSTTY_RING_SIZE * 1) / 4;
+u_int zstty_rbuf_lowat = (ZSTTY_RING_SIZE * 3) / 4;
+
+struct zstty_softc {
+	struct	device zst_dev;		/* required first: base device */
+	struct  tty *zst_tty;
+	struct	zs_chanstate *zst_cs;
+
+        struct timeout zst_diag_ch;
+
+	u_int zst_overflows,
+	      zst_floods,
+	      zst_errors;
+
+	int zst_hwflags,	/* see z8530var.h */
+	    zst_swflags;	/* TIOCFLAG_SOFTCAR, ... <ttycom.h> */
+
+	u_int zst_r_hiwat,
+	      zst_r_lowat;
+	u_char *volatile zst_rbget,
+	       *volatile zst_rbput;
+	volatile u_int zst_rbavail;
+	u_char *zst_rbuf,
+	       *zst_ebuf;
+
+	/*
+	 * The transmit byte count and address are used for pseudo-DMA
+	 * output in the hardware interrupt code.  PDMA can be suspended
+	 * to get pending changes done; heldtbc is used for this.  It can
+	 * also be stopped for ^S; this sets TS_TTSTOP in tp->t_state.
+	 */
+	u_char *zst_tba;		/* transmit buffer address */
+	u_int zst_tbc,			/* transmit byte count */
+	      zst_heldtbc;		/* held tbc while xmission stopped */
+
+	/* Flags to communicate with zstty_softint() */
+	volatile u_char zst_rx_flags,	/* receiver blocked */
+#define RX_TTY_BLOCKED          0x01
+#define RX_TTY_OVERFLOWED       0x02
+#define RX_IBUF_BLOCKED         0x04
+#define RX_IBUF_OVERFLOWED      0x08
+#define RX_ANY_BLOCK            0x0f
+			zst_tx_busy,	/* working on an output chunk */
+			zst_tx_done,	/* done with one output chunk */
+			zst_tx_stopped,	/* H/W level stop (lost CTS) */
+			zst_st_check,	/* got a status interrupt */
+			zst_rx_ready;
+
+	/* PPS signal on DCD, with or without inkernel clock disciplining */
+	u_char  zst_ppsmask;			/* pps signal mask */
+	u_char  zst_ppsassert;			/* pps leading edge */
+	u_char  zst_ppsclear;			/* pps trailing edge */
+};
+
+
+/* Definition of the driver for autoconfig. */
+int	zstty_match(struct device *, void *, void *);
+void	zstty_attach(struct device *, struct device *, void *);
+
+struct cfattach zstty_ca = {
+	sizeof(struct zstty_softc), zstty_match, zstty_attach
+};
+
+struct cfdriver zstty_cd = {
+	NULL, "zstty", DV_TTY
+};
+
+struct zsops zsops_tty;
+
+/* Routines called from other code. */
+cdev_decl(zs);	/* open, close, read, write, ioctl, stop, ... */
+
+void zs_shutdown(struct zstty_softc *);
+void	zsstart(struct tty *);
+int	zsparam(struct tty *, struct termios *);
+void zs_modem(struct zstty_softc *, int);
+void tiocm_to_zs(struct zstty_softc *, u_long, int);
+int  zs_to_tiocm(struct zstty_softc *);
+int    zshwiflow(struct tty *, int);
+void  zs_hwiflow(struct zstty_softc *);
+void zs_maskintr(struct zstty_softc *);
+
+/* Low-level routines. */
+void zstty_rxint(struct zs_chanstate *);
+void zstty_stint(struct zs_chanstate *, int);
+void zstty_txint(struct zs_chanstate *);
+void zstty_softint(struct zs_chanstate *);
+void zstty_diag(void *);
+
+#define ZSUNIT(x)       (minor(x) & 0x7ffff)
+#define ZSDIALOUT(x)    (minor(x) & 0x80000)
+
+/*
+ * zstty_match: how is this zs channel configured?
+ */
+int
+zstty_match(parent, match, aux)
+	struct device *parent;
+	void   *match, *aux;
+{
+	struct cfdata *cf = match;
+	struct zsc_attach_args *args = aux;
+
+	/* Exact match is better than wildcard. */
+	if (cf->cf_loc[ZSCCF_CHANNEL] == args->channel)
+		return 2;
+
+	/* This driver accepts wildcard. */
+	if (cf->cf_loc[ZSCCF_CHANNEL] == ZSCCF_CHANNEL_DEFAULT)
+		return 1;
+
+	return 0;
+}
+
+void
+zstty_attach(parent, self, aux)
+	struct device *parent, *self;
+	void   *aux;
+
+{
+	struct zsc_softc *zsc = (void *) parent;
+	struct zstty_softc *zst = (void *) self;
+	struct zsc_attach_args *args = aux;
+	struct zs_chanstate *cs;
+	struct cfdata *cf;
+	struct tty *tp;
+	int channel, s, tty_unit;
+	dev_t dev;
+	char *i, *o;
+
+	cf = zst->zst_dev.dv_cfdata;
+
+        timeout_set(&zst->zst_diag_ch, zstty_diag, zst);
+
+	tty_unit = zst->zst_dev.dv_unit;
+	channel = args->channel;
+	cs = &zsc->zsc_cs[channel];
+	cs->cs_private = zst;
+	cs->cs_ops = &zsops_tty;
+
+	zst->zst_cs = cs;
+	zst->zst_swflags = cf->cf_flags;	/* softcar, etc. */
+	zst->zst_hwflags = args->hwflags;
+	dev = makedev(zs_major, tty_unit);
+
+	if (zst->zst_swflags)
+		printf(" flags 0x%x", zst->zst_swflags);
+
+	/*
+	 * Check whether we serve as a console device.
+	 * XXX - split console input/output channels aren't
+	 *       supported yet on /dev/console
+	 */
+	i = o = NULL;
+	if ((zst->zst_hwflags & ZS_HWFLAG_CONSOLE_INPUT) != 0) {
+		i = "input";
+		if ((args->hwflags & ZS_HWFLAG_USE_CONSDEV) != 0) {
+			args->consdev->cn_dev = dev;
+			cn_tab->cn_pollc = args->consdev->cn_pollc;
+			cn_tab->cn_getc = args->consdev->cn_getc;
+		}
+		cn_tab->cn_dev = dev;
+		/* Set console magic to BREAK */
+	}
+	if ((zst->zst_hwflags & ZS_HWFLAG_CONSOLE_OUTPUT) != 0) {
+		o = "output";
+		if ((args->hwflags & ZS_HWFLAG_USE_CONSDEV) != 0) {
+			cn_tab->cn_putc = args->consdev->cn_putc;
+		}
+		cn_tab->cn_dev = dev;
+	}
+	if (i != NULL || o != NULL)
+		printf(" (console %s)", i ? (o ? "i/o" : i) : o);
+
+#ifdef KGDB
+	/*
+	 * Allow kgdb to "take over" this port.  If this port is
+	 * NOT the kgdb port, zs_check_kgdb() will return zero.
+	 * If it IS the kgdb port, it will print "kgdb,...\n"
+	 * and then return non-zero.
+	 */
+	if (zs_check_kgdb(cs, dev)) {
+		printf(" (kgdb)\n");
+		/*
+		 * This is the kgdb port (exclusive use)
+		 * so skip the normal attach code.
+		 */
+		return;
+	}
+#endif
+
+	if (strcmp(args->type, "keyboard") == 0 ||
+	    strcmp(args->type, "mouse") == 0)
+		printf(": %s", args->type);
+
+	printf("\n");
+
+	tp = ttymalloc();
+	tp->t_dev = dev;
+	tp->t_oproc = zsstart;
+	tp->t_param = zsparam;
+	tp->t_hwiflow = zshwiflow;
+	tty_attach(tp);
+
+	zst->zst_tty = tp;
+	zst->zst_rbuf = malloc(zstty_rbuf_size << 1, M_DEVBUF, M_WAITOK);
+	zst->zst_ebuf = zst->zst_rbuf + (zstty_rbuf_size << 1);
+	/* Disable the high water mark. */
+	zst->zst_r_hiwat = 0;
+	zst->zst_r_lowat = 0;
+	zst->zst_rbget = zst->zst_rbput = zst->zst_rbuf;
+	zst->zst_rbavail = zstty_rbuf_size;
+
+	/* if there are no enable/disable functions, assume the device
+	   is always enabled */
+	if (!cs->enable)
+		cs->enabled = 1;
+
+	/*
+	 * Hardware init
+	 */
+	if (ISSET(zst->zst_hwflags, ZS_HWFLAG_CONSOLE)) {
+		/* Call zsparam similar to open. */
+		struct termios t;
+
+		/* Wait a while for previous console output to complete */
+		DELAY(10000);
+
+		/* Setup the "new" parameters in t. */
+		t.c_ispeed = 0;
+		t.c_ospeed = cs->cs_defspeed;
+		t.c_cflag = cs->cs_defcflag;
+
+		s = splzs();
+
+		/*
+		 * Turn on receiver and status interrupts.
+		 * We defer the actual write of the register to zsparam(),
+		 * but we must make sure status interrupts are turned on by
+		 * the time zsparam() reads the initial rr0 state.
+		 */
+		SET(cs->cs_preg[1], ZSWR1_RIE | ZSWR1_SIE);
+
+		splx(s);
+
+		/* Make sure zsparam will see changes. */
+		tp->t_ospeed = 0;
+		(void) zsparam(tp, &t);
+
+		s = splzs();
+
+		/* Make sure DTR is on now. */
+		zs_modem(zst, 1);
+
+		splx(s);
+	} else if (!ISSET(zst->zst_hwflags, ZS_HWFLAG_NORESET)) {
+		/* Not the console; may need reset. */
+		int reset;
+
+		reset = (channel == 0) ? ZSWR9_A_RESET : ZSWR9_B_RESET;
+
+		s = splzs();
+
+		zs_write_reg(cs, 9, reset);
+
+		/* Will raise DTR in open. */
+		zs_modem(zst, 0);
+
+		splx(s);
+	}
+}
+
+
+/*
+ * Return pointer to our tty.
+ */
+struct tty *
+zstty(dev)
+	dev_t dev;
+{
+	struct zstty_softc *zst;
+	int unit = minor(dev);
+
+#ifdef	DIAGNOSTIC
+	if (unit >= zstty_cd.cd_ndevs)
+		panic("zstty");
+#endif
+	zst = zstty_cd.cd_devs[unit];
+	return (zst->zst_tty);
+}
+
+
+void
+zs_shutdown(zst)
+	struct zstty_softc *zst;
+{
+	struct zs_chanstate *cs = zst->zst_cs;
+	struct tty *tp = zst->zst_tty;
+	int s;
+
+	s = splzs();
+
+	/* If we were asserting flow control, then deassert it. */
+	SET(zst->zst_rx_flags, RX_IBUF_BLOCKED);
+	zs_hwiflow(zst);
+
+	/* Clear any break condition set with TIOCSBRK. */
+	zs_break(cs, 0);
+
+	/* Turn off PPS capture on last close. */
+	zst->zst_ppsmask = 0;
+
+	/*
+	 * Hang up if necessary.  Wait a bit, so the other side has time to
+	 * notice even if we immediately open the port again.
+	 */
+	if (ISSET(tp->t_cflag, HUPCL)) {
+		zs_modem(zst, 0);
+		(void) tsleep(cs, TTIPRI, ttclos, hz);
+	}
+
+	/* Turn off interrupts if not the console. */
+	if (!ISSET(zst->zst_hwflags, ZS_HWFLAG_CONSOLE)) {
+		CLR(cs->cs_preg[1], ZSWR1_RIE | ZSWR1_SIE);
+		cs->cs_creg[1] = cs->cs_preg[1];
+		zs_write_reg(cs, 1, cs->cs_creg[1]);
+	}
+
+/* Call the power management hook. */
+	if (cs->disable) {
+#ifdef DIAGNOSTIC
+		if (!cs->enabled)
+			panic("zs_shutdown: not enabled?");
+#endif
+		(*cs->disable)(zst->zst_cs);
+	}
+
+	splx(s);
+}
+
+/*
+ * Open a zs serial (tty) port.
+ */
+int
+zsopen(dev, flags, mode, p)
+	dev_t dev;
+	int flags;
+	int mode;
+	struct proc *p;
+{
+	register struct tty *tp;
+	register struct zs_chanstate *cs;
+	struct zstty_softc *zst;
+	int s, s2;
+	int error, unit;
+
+	unit = minor(dev);
+	if (unit >= zstty_cd.cd_ndevs)
+		return (ENXIO);
+	zst = zstty_cd.cd_devs[unit];
+	if (zst == NULL)
+		return (ENXIO);
+	tp = zst->zst_tty;
+	cs = zst->zst_cs;
+
+	/* If KGDB took the line, then tp==NULL */
+	if (tp == NULL)
+		return (EBUSY);
+
+	if (ISSET(tp->t_state, TS_ISOPEN) &&
+	    ISSET(tp->t_state, TS_XCLUDE) &&
+	    p->p_ucred->cr_uid != 0)
+		return (EBUSY);
+
+	s = spltty();
+
+	/*
+	 * Do the following iff this is a first open.
+	 */
+	if (!ISSET(tp->t_state, TS_ISOPEN)) {
+		struct termios t;
+
+		tp->t_dev = dev;
+
+		/* Call the power management hook. */
+		if (cs->enable) {
+			if ((*cs->enable)(cs)) {
+				splx(s);
+				printf("%s: device enable failed\n",
+				zst->zst_dev.dv_xname);
+				return (EIO);
+			}
+		}
+
+		/*
+		 * Initialize the termios status to the defaults.  Add in the
+		 * sticky bits from TIOCSFLAGS.
+		 */
+		t.c_ispeed = 0;
+		t.c_ospeed = cs->cs_defspeed;
+		t.c_cflag = cs->cs_defcflag;
+		if (ISSET(zst->zst_swflags, TIOCFLAG_CLOCAL))
+			SET(t.c_cflag, CLOCAL);
+		if (ISSET(zst->zst_swflags, TIOCFLAG_CRTSCTS))
+			SET(t.c_cflag, CRTSCTS);
+		if (ISSET(zst->zst_swflags, TIOCFLAG_MDMBUF))
+			SET(t.c_cflag, MDMBUF);
+
+		s2 = splzs();
+
+		/*
+		 * Turn on receiver and status interrupts.
+		 * We defer the actual write of the register to zsparam(),
+		 * but we must make sure status interrupts are turned on by
+		 * the time zsparam() reads the initial rr0 state.
+		 */
+		SET(cs->cs_preg[1], ZSWR1_RIE | ZSWR1_SIE);
+
+		/* Clear PPS capture state on first open. */
+		zst->zst_ppsmask = 0;
+
+		splx(s2);
+
+		/* Make sure zsparam will see changes. */
+		tp->t_ospeed = 0;
+		(void) zsparam(tp, &t);
+
+		/*
+		 * Note: zsparam has done: cflag, ispeed, ospeed
+		 * so we just need to do: iflag, oflag, lflag, cc
+		 * For "raw" mode, just leave all zeros.
+		 */
+		if (!ISSET(zst->zst_hwflags, ZS_HWFLAG_RAW)) {
+			tp->t_iflag = TTYDEF_IFLAG;
+			tp->t_oflag = TTYDEF_OFLAG;
+			tp->t_lflag = TTYDEF_LFLAG;
+		} else {
+			tp->t_iflag = 0;
+			tp->t_oflag = 0;
+			tp->t_lflag = 0;
+		}
+		ttychars(tp);
+		ttsetwater(tp);
+
+		s2 = splzs();
+
+		/*
+		 * Turn on DTR.  We must always do this, even if carrier is not
+		 * present, because otherwise we'd have to use TIOCSDTR
+		 * immediately after setting CLOCAL, which applications do not
+		 * expect.  We always assert DTR while the device is open
+		 * unless explicitly requested to deassert it.
+		 */
+		zs_modem(zst, 1);
+
+		/* Clear the input ring, and unblock. */
+		zst->zst_rbget = zst->zst_rbput = zst->zst_rbuf;
+		zst->zst_rbavail = zstty_rbuf_size;
+		zs_iflush(cs);
+		CLR(zst->zst_rx_flags, RX_ANY_BLOCK);
+		zs_hwiflow(zst);
+
+		splx(s2);
+	}
+
+	splx(s);
+
+	error = ((*linesw[tp->t_line].l_open)(dev, tp));
+	if (error)
+		goto bad;
+
+	return (0);
+
+bad:
+	if (!ISSET(tp->t_state, TS_ISOPEN)) {
+		/*
+		 * We failed to open the device, and nobody else had it opened.
+		 * Clean up the state as appropriate.
+		 */
+		zs_shutdown(zst);
+	}
+
+	return (error);
+}
+
+/*
+ * Close a zs serial port.
+ */
+int
+zsclose(dev, flags, mode, p)
+	dev_t dev;
+	int flags;
+	int mode;
+	struct proc *p;
+{
+	struct zstty_softc *zst;
+	register struct zs_chanstate *cs;
+	register struct tty *tp;
+
+	zst = zstty_cd.cd_devs[minor(dev)];
+	cs = zst->zst_cs;
+	tp = zst->zst_tty;
+
+	/* XXX This is for cons.c. */
+	if (!ISSET(tp->t_state, TS_ISOPEN))
+		return 0;
+
+	(*linesw[tp->t_line].l_close)(tp, flags);
+	ttyclose(tp);
+
+	if (!ISSET(tp->t_state, TS_ISOPEN)) {
+		/*
+		 * Although we got a last close, the device may still be in
+		 * use; e.g. if this was the dialout node, and there are still
+		 * processes waiting for carrier on the non-dialout node.
+		 */
+		zs_shutdown(zst);
+	}
+
+	return (0);
+}
+
+/*
+ * Read/write zs serial port.
+ */
+int
+zsread(dev, uio, flags)
+	dev_t dev;
+	struct uio *uio;
+	int flags;
+{
+	struct zstty_softc *zst;
+	struct tty *tp;
+
+	zst = zstty_cd.cd_devs[minor(dev)];
+	tp = zst->zst_tty;
+
+	return (*linesw[tp->t_line].l_read)(tp, uio, flags);
+}
+
+int
+zswrite(dev, uio, flags)
+	dev_t dev;
+	struct uio *uio;
+	int flags;
+{
+	struct zstty_softc *zst;
+	struct tty *tp;
+
+	zst = zstty_cd.cd_devs[minor(dev)];
+	tp = zst->zst_tty;
+
+	return (*linesw[tp->t_line].l_write)(tp, uio, flags);
+}
+
+#define TIOCFLAG_ALL (TIOCFLAG_SOFTCAR | TIOCFLAG_CLOCAL | \
+                      TIOCFLAG_CRTSCTS | TIOCFLAG_MDMBUF )
+
+int
+zsioctl(dev, cmd, data, flag, p)
+	dev_t dev;
+	u_long cmd;
+	caddr_t data;
+	int flag;
+	struct proc *p;
+{
+	struct zstty_softc *zst;
+	struct zs_chanstate *cs;
+	struct tty *tp;
+	int error;
+	int s;
+
+	zst = zstty_cd.cd_devs[minor(dev)];
+	cs = zst->zst_cs;
+	tp = zst->zst_tty;
+
+	error = ((*linesw[tp->t_line].l_ioctl)(tp, cmd, data, flag, p));
+	if (error >= 0)
+		return (error);
+
+	error = ttioctl(tp, cmd, data, flag, p);
+	if (error >= 0)
+		return (error);
+
+#ifdef	ZS_MD_IOCTL
+	error = ZS_MD_IOCTL;
+	if (error >= 0)
+		return (error);
+#endif	/* ZS_MD_IOCTL */
+
+	error = 0;
+
+	s = splzs();
+
+	switch (cmd) {
+	case TIOCSBRK:
+		zs_break(cs, 1);
+		break;
+
+	case TIOCCBRK:
+		zs_break(cs, 0);
+		break;
+
+	case TIOCGFLAGS:
+		*(int *)data = zst->zst_swflags;
+		break;
+
+	case TIOCSFLAGS:
+		error = suser(p->p_ucred, &p->p_acflag);
+		if (error != 0)
+			break;
+		zst->zst_swflags = *(int *)data;
+		break;
+
+	case TIOCSDTR:
+		zs_modem(zst, 1);
+		break;
+
+	case TIOCCDTR:
+		zs_modem(zst, 0);
+		break;
+
+	case TIOCMSET:
+	case TIOCMBIS:
+	case TIOCMBIC:
+		tiocm_to_zs(zst, cmd, *(int *)data);
+		break;
+
+	case TIOCMGET:
+		*(int *)data = zs_to_tiocm(zst);
+		break;
+
+	default:
+		error = ENOTTY;
+		break;
+	}
+
+	splx(s);
+
+	return (error);
+}
+
+/*
+ * Start or restart transmission.
+ */
+void
+zsstart(tp)
+	struct tty *tp;
+{
+	struct zstty_softc *zst;
+	struct zs_chanstate *cs;
+	int s;
+
+	zst = zstty_cd.cd_devs[minor(tp->t_dev)];
+	cs = zst->zst_cs;
+
+	s = spltty();
+	if (ISSET(tp->t_state, TS_BUSY | TS_TIMEOUT | TS_TTSTOP))
+		goto out;
+	if (zst->zst_tx_stopped)
+		goto out;
+
+	if (tp->t_outq.c_cc <= tp->t_lowat) {
+		if (ISSET(tp->t_state, TS_ASLEEP)) {
+			CLR(tp->t_state, TS_ASLEEP);
+			wakeup((caddr_t)&tp->t_outq);
+		}
+		selwakeup(&tp->t_wsel);
+		if (tp->t_outq.c_cc == 0)
+			goto out;
+	}
+
+	/* Grab the first contiguous region of buffer space. */
+	{
+		u_char *tba;
+		int tbc;
+
+		tba = tp->t_outq.c_cf;
+		tbc = ndqb(&tp->t_outq, 0);
+
+		(void) splzs();
+
+		zst->zst_tba = tba;
+		zst->zst_tbc = tbc;
+	}
+
+	SET(tp->t_state, TS_BUSY);
+	zst->zst_tx_busy = 1;
+
+	/* Enable transmit completion interrupts if necessary. */
+	if (!ISSET(cs->cs_preg[1], ZSWR1_TIE)) {
+		SET(cs->cs_preg[1], ZSWR1_TIE);
+		cs->cs_creg[1] = cs->cs_preg[1];
+		zs_write_reg(cs, 1, cs->cs_creg[1]);
+	}
+
+	/* Output the first character of the contiguous buffer. */
+	{
+		zs_write_data(cs, *zst->zst_tba);
+		zst->zst_tbc--;
+		zst->zst_tba++;
+	}
+out:
+	splx(s);
+}
+
+/*
+ * Stop output, e.g., for ^S or output flush.
+ */
+int
+zsstop(tp, flag)
+	struct tty *tp;
+	int flag;
+{
+	struct zstty_softc *zst;
+	struct zs_chanstate *cs;
+	int s;
+
+	zst = zstty_cd.cd_devs[minor(tp->t_dev)];
+	cs = zst->zst_cs;
+
+	s = splzs();
+	if (ISSET(tp->t_state, TS_BUSY)) {
+		/* Stop transmitting at the next chunk. */
+		zst->zst_tbc = 0;
+		zst->zst_heldtbc = 0;
+		if (!ISSET(tp->t_state, TS_TTSTOP))
+			SET(tp->t_state, TS_FLUSH);
+	}
+	splx(s);
+	return (0);
+}
+
+/*
+ * Set ZS tty parameters from termios.
+ * XXX - Should just copy the whole termios after
+ * making sure all the changes could be done.
+ */
+int
+zsparam(tp, t)
+	struct tty *tp;
+	struct termios *t;
+{
+	struct zstty_softc *zst;
+	struct zs_chanstate *cs;
+	int ospeed, cflag;
+	u_char tmp3, tmp4, tmp5;
+	int s, error;
+
+	zst = zstty_cd.cd_devs[minor(tp->t_dev)];
+	cs = zst->zst_cs;
+
+	ospeed = t->c_ospeed;
+	cflag = t->c_cflag;
+
+	/* Check requested parameters. */
+	if (ospeed < 0)
+		return (EINVAL);
+	if (t->c_ispeed && t->c_ispeed != ospeed)
+		return (EINVAL);
+
+	/*
+	 * For the console, always force CLOCAL and !HUPCL, so that the port
+	 * is always active.
+	 */
+	if (ISSET(zst->zst_swflags, TIOCFLAG_SOFTCAR) ||
+	    ISSET(zst->zst_hwflags, ZS_HWFLAG_CONSOLE)) {
+		SET(cflag, CLOCAL);
+		CLR(cflag, HUPCL);
+	}
+
+	/*
+	 * Only whack the UART when params change.
+	 * Some callers need to clear tp->t_ospeed
+	 * to make sure initialization gets done.
+	 */
+	if (tp->t_ospeed == ospeed &&
+	    tp->t_cflag == cflag)
+		return (0);
+
+	/*
+	 * Call MD functions to deal with changed
+	 * clock modes or H/W flow control modes.
+	 * The BRG divisor is set now. (reg 12,13)
+	 */
+	error = zs_set_speed(cs, ospeed);
+	if (error)
+		return (error);
+	error = zs_set_modes(cs, cflag);
+	if (error)
+		return (error);
+
+	/*
+	 * Block interrupts so that state will not
+	 * be altered until we are done setting it up.
+	 *
+	 * Initial values in cs_preg are set before
+	 * our attach routine is called.  The master
+	 * interrupt enable is handled by zsc.c
+	 */
+	s = splzs();
+
+	/*
+	 * Recalculate which status ints to enable.
+	 */
+	zs_maskintr(zst);
+
+	/* Recompute character size bits. */
+	tmp3 = cs->cs_preg[3];
+	tmp5 = cs->cs_preg[5];
+	CLR(tmp3, ZSWR3_RXSIZE);
+	CLR(tmp5, ZSWR5_TXSIZE);
+	switch (ISSET(cflag, CSIZE)) {
+	case CS5:
+		SET(tmp3, ZSWR3_RX_5);
+		SET(tmp5, ZSWR5_TX_5);
+		break;
+	case CS6:
+		SET(tmp3, ZSWR3_RX_6);
+		SET(tmp5, ZSWR5_TX_6);
+		break;
+	case CS7:
+		SET(tmp3, ZSWR3_RX_7);
+		SET(tmp5, ZSWR5_TX_7);
+		break;
+	case CS8:
+		SET(tmp3, ZSWR3_RX_8);
+		SET(tmp5, ZSWR5_TX_8);
+		break;
+	}
+	cs->cs_preg[3] = tmp3;
+	cs->cs_preg[5] = tmp5;
+
+	/*
+	 * Recompute the stop bits and parity bits.  Note that
+	 * zs_set_speed() may have set clock selection bits etc.
+	 * in wr4, so those must preserved.
+	 */
+	tmp4 = cs->cs_preg[4];
+	CLR(tmp4, ZSWR4_SBMASK | ZSWR4_PARMASK);
+	if (ISSET(cflag, CSTOPB))
+		SET(tmp4, ZSWR4_TWOSB);
+	else
+		SET(tmp4, ZSWR4_ONESB);
+	if (!ISSET(cflag, PARODD))
+		SET(tmp4, ZSWR4_EVENP);
+	if (ISSET(cflag, PARENB))
+		SET(tmp4, ZSWR4_PARENB);
+	cs->cs_preg[4] = tmp4;
+
+	/* And copy to tty. */
+	tp->t_ispeed = 0;
+	tp->t_ospeed = ospeed;
+	tp->t_cflag = cflag;
+
+	/*
+	 * If nothing is being transmitted, set up new current values,
+	 * else mark them as pending.
+	 */
+	if (!cs->cs_heldchange) {
+		if (zst->zst_tx_busy) {
+			zst->zst_heldtbc = zst->zst_tbc;
+			zst->zst_tbc = 0;
+			cs->cs_heldchange = 1;
+		} else
+			zs_loadchannelregs(cs);
+	}
+
+	/*
+	 * If hardware flow control is disabled, turn off the buffer water
+	 * marks and unblock any soft flow control state.  Otherwise, enable
+	 * the water marks.
+	 */
+	if (!ISSET(cflag, CHWFLOW)) {
+		zst->zst_r_hiwat = 0;
+		zst->zst_r_lowat = 0;
+		if (ISSET(zst->zst_rx_flags, RX_TTY_OVERFLOWED)) {
+			CLR(zst->zst_rx_flags, RX_TTY_OVERFLOWED);
+			zst->zst_rx_ready = 1;
+			cs->cs_softreq = 1;
+		}
+		if (ISSET(zst->zst_rx_flags, RX_TTY_BLOCKED|RX_IBUF_BLOCKED)) {
+			CLR(zst->zst_rx_flags, RX_TTY_BLOCKED|RX_IBUF_BLOCKED);
+			zs_hwiflow(zst);
+		}
+	} else {
+		zst->zst_r_hiwat = zstty_rbuf_hiwat;
+		zst->zst_r_lowat = zstty_rbuf_lowat;
+	}
+
+	/*
+	 * Force a recheck of the hardware carrier and flow control status,
+	 * since we may have changed which bits we're looking at.
+	 */
+	zstty_stint(cs, 1);
+
+	splx(s);
+
+	/*
+	 * If hardware flow control is disabled, unblock any hard flow control
+	 * state.
+	 */
+	if (!ISSET(cflag, CHWFLOW)) {
+		if (zst->zst_tx_stopped) {
+			zst->zst_tx_stopped = 0;
+			zsstart(tp);
+		}
+	}
+
+	zstty_softint(cs);
+
+	return (0);
+}
+
+/*
+ * Compute interupt enable bits and set in the pending bits. Called both
+ * in zsparam() and when PPS (pulse per second timing) state changes.
+ * Must be called at splzs().
+ */
+void
+zs_maskintr(zst)
+	struct zstty_softc *zst;
+{
+	struct zs_chanstate *cs = zst->zst_cs;
+	int tmp15;
+
+	cs->cs_rr0_mask = cs->cs_rr0_cts | cs->cs_rr0_dcd;
+	if (zst->zst_ppsmask != 0)
+		cs->cs_rr0_mask |= cs->cs_rr0_pps;
+	tmp15 = cs->cs_preg[15];
+	if (ISSET(cs->cs_rr0_mask, ZSRR0_DCD))
+		SET(tmp15, ZSWR15_DCD_IE);
+	else
+		CLR(tmp15, ZSWR15_DCD_IE);
+	if (ISSET(cs->cs_rr0_mask, ZSRR0_CTS))
+		SET(tmp15, ZSWR15_CTS_IE);
+	else
+		CLR(tmp15, ZSWR15_CTS_IE);
+	cs->cs_preg[15] = tmp15;
+}
+
+/*
+ * Raise or lower modem control (DTR/RTS) signals.  If a character is
+ * in transmission, the change is deferred.
+ */
+void
+zs_modem(zst, onoff)
+	struct zstty_softc *zst;
+	int onoff;
+{
+	struct zs_chanstate *cs = zst->zst_cs;
+
+	if (cs->cs_wr5_dtr == 0)
+		return;
+
+	if (onoff)
+		SET(cs->cs_preg[5], cs->cs_wr5_dtr);
+	else
+		CLR(cs->cs_preg[5], cs->cs_wr5_dtr);
+
+	if (!cs->cs_heldchange) {
+		if (zst->zst_tx_busy) {
+			zst->zst_heldtbc = zst->zst_tbc;
+			zst->zst_tbc = 0;
+			cs->cs_heldchange = 1;
+		} else
+			zs_loadchannelregs(cs);
+	}
+}
+
+void
+tiocm_to_zs(zst, how, ttybits)
+	struct zstty_softc *zst;
+	u_long how;
+	int ttybits;
+{
+	struct zs_chanstate *cs = zst->zst_cs;
+	u_char zsbits;
+
+	zsbits = 0;
+	if (ISSET(ttybits, TIOCM_DTR))
+		SET(zsbits, ZSWR5_DTR);
+	if (ISSET(ttybits, TIOCM_RTS))
+		SET(zsbits, ZSWR5_RTS);
+
+	switch (how) {
+	case TIOCMBIC:
+		CLR(cs->cs_preg[5], zsbits);
+		break;
+
+	case TIOCMBIS:
+		SET(cs->cs_preg[5], zsbits);
+		break;
+
+	case TIOCMSET:
+		CLR(cs->cs_preg[5], ZSWR5_RTS | ZSWR5_DTR);
+		SET(cs->cs_preg[5], zsbits);
+		break;
+	}
+
+	if (!cs->cs_heldchange) {
+		if (zst->zst_tx_busy) {
+			zst->zst_heldtbc = zst->zst_tbc;
+			zst->zst_tbc = 0;
+			cs->cs_heldchange = 1;
+		} else
+			zs_loadchannelregs(cs);
+	}
+}
+
+int
+zs_to_tiocm(zst)
+	struct zstty_softc *zst;
+{
+	struct zs_chanstate *cs = zst->zst_cs;
+	u_char zsbits;
+	int ttybits = 0;
+
+	zsbits = cs->cs_preg[5];
+	if (ISSET(zsbits, ZSWR5_DTR))
+		SET(ttybits, TIOCM_DTR);
+	if (ISSET(zsbits, ZSWR5_RTS))
+		SET(ttybits, TIOCM_RTS);
+
+	zsbits = cs->cs_rr0;
+	if (ISSET(zsbits, ZSRR0_DCD))
+		SET(ttybits, TIOCM_CD);
+	if (ISSET(zsbits, ZSRR0_CTS))
+		SET(ttybits, TIOCM_CTS);
+
+	return (ttybits);
+}
+
+/*
+ * Try to block or unblock input using hardware flow-control.
+ * This is called by kern/tty.c if MDMBUF|CRTSCTS is set, and
+ * if this function returns non-zero, the TS_TBLOCK flag will
+ * be set or cleared according to the "block" arg passed.
+ */
+int
+zshwiflow(tp, block)
+	struct tty *tp;
+	int block;
+{
+	struct zstty_softc *zst;
+	struct zs_chanstate *cs;
+	int s;
+
+	zst = zstty_cd.cd_devs[minor(tp->t_dev)];
+	cs = zst->zst_cs;
+
+	if (cs->cs_wr5_rts == 0)
+		return (0);
+
+	s = splzs();
+	if (block) {
+		if (!ISSET(zst->zst_rx_flags, RX_TTY_BLOCKED)) {
+			SET(zst->zst_rx_flags, RX_TTY_BLOCKED);
+			zs_hwiflow(zst);
+		}
+	} else {
+		if (ISSET(zst->zst_rx_flags, RX_TTY_OVERFLOWED)) {
+			CLR(zst->zst_rx_flags, RX_TTY_OVERFLOWED);
+			zst->zst_rx_ready = 1;
+			cs->cs_softreq = 1;
+		}
+		if (ISSET(zst->zst_rx_flags, RX_TTY_BLOCKED)) {
+			CLR(zst->zst_rx_flags, RX_TTY_BLOCKED);
+			zs_hwiflow(zst);
+		}
+	}
+	splx(s);
+	return (1);
+}
+
+/*
+ * Internal version of zshwiflow
+ * called at splzs
+ */
+void
+zs_hwiflow(zst)
+	struct zstty_softc *zst;
+{
+	struct zs_chanstate *cs = zst->zst_cs;
+
+	if (cs->cs_wr5_rts == 0)
+		return;
+
+	if (ISSET(zst->zst_rx_flags, RX_ANY_BLOCK)) {
+		CLR(cs->cs_preg[5], cs->cs_wr5_rts);
+		CLR(cs->cs_creg[5], cs->cs_wr5_rts);
+	} else {
+		SET(cs->cs_preg[5], cs->cs_wr5_rts);
+		SET(cs->cs_creg[5], cs->cs_wr5_rts);
+	}
+	zs_write_reg(cs, 5, cs->cs_creg[5]);
+}
+
+
+/****************************************************************
+ * Interface to the lower layer (zscc)
+ ****************************************************************/
+
+void zstty_rxsoft(struct zstty_softc *, struct tty *);
+void zstty_txsoft(struct zstty_softc *, struct tty *);
+void zstty_stsoft(struct zstty_softc *, struct tty *);
+
+/*
+ * receiver ready interrupt.
+ * called at splzs
+ */
+void
+zstty_rxint(cs)
+	struct zs_chanstate *cs;
+{
+	struct zstty_softc *zst = cs->cs_private;
+	u_char *put, *end;
+	u_int cc;
+	u_char rr0, rr1, c;
+
+	end = zst->zst_ebuf;
+	put = zst->zst_rbput;
+	cc = zst->zst_rbavail;
+
+	while (cc > 0) {
+		/*
+		 * First read the status, because reading the received char
+		 * destroys the status of this char.
+		 */
+		rr1 = zs_read_reg(cs, 1);
+		c = zs_read_data(cs);
+
+		if (ISSET(rr1, ZSRR1_FE | ZSRR1_DO | ZSRR1_PE)) {
+			/* Clear the receive error. */
+			zs_write_csr(cs, ZSWR0_RESET_ERRORS);
+		}
+
+		put[0] = c;
+		put[1] = rr1;
+		put += 2;
+		if (put >= end)
+			put = zst->zst_rbuf;
+		cc--;
+
+		rr0 = zs_read_csr(cs);
+		if (!ISSET(rr0, ZSRR0_RX_READY))
+			break;
+	}
+
+	/*
+	 * Current string of incoming characters ended because
+	 * no more data was available or we ran out of space.
+	 * Schedule a receive event if any data was received.
+	 * If we're out of space, turn off receive interrupts.
+	 */
+	zst->zst_rbput = put;
+	zst->zst_rbavail = cc;
+	if (!ISSET(zst->zst_rx_flags, RX_TTY_OVERFLOWED)) {
+		zst->zst_rx_ready = 1;
+		cs->cs_softreq = 1;
+	}
+
+	/*
+	 * See if we are in danger of overflowing a buffer. If
+	 * so, use hardware flow control to ease the pressure.
+	 */
+	if (!ISSET(zst->zst_rx_flags, RX_IBUF_BLOCKED) &&
+	    cc < zst->zst_r_hiwat) {
+		SET(zst->zst_rx_flags, RX_IBUF_BLOCKED);
+		zs_hwiflow(zst);
+	}
+
+	/*
+	 * If we're out of space, disable receive interrupts
+	 * until the queue has drained a bit.
+	 */
+	if (!cc) {
+		SET(zst->zst_rx_flags, RX_IBUF_OVERFLOWED);
+		CLR(cs->cs_preg[1], ZSWR1_RIE);
+		cs->cs_creg[1] = cs->cs_preg[1];
+		zs_write_reg(cs, 1, cs->cs_creg[1]);
+	}
+}
+
+/*
+ * transmitter ready interrupt.  (splzs)
+ */
+void
+zstty_txint(cs)
+	struct zs_chanstate *cs;
+{
+	struct zstty_softc *zst = cs->cs_private;
+
+	/*
+	 * If we've delayed a parameter change, do it now, and restart
+	 * output.
+	 */
+	if (cs->cs_heldchange) {
+		zs_loadchannelregs(cs);
+		cs->cs_heldchange = 0;
+		zst->zst_tbc = zst->zst_heldtbc;
+		zst->zst_heldtbc = 0;
+	}
+
+	/* Output the next character in the buffer, if any. */
+	if (zst->zst_tbc > 0) {
+		zs_write_data(cs, *zst->zst_tba);
+		zst->zst_tbc--;
+		zst->zst_tba++;
+	} else {
+		/* Disable transmit completion interrupts if necessary. */
+		if (ISSET(cs->cs_preg[1], ZSWR1_TIE)) {
+			CLR(cs->cs_preg[1], ZSWR1_TIE);
+			cs->cs_creg[1] = cs->cs_preg[1];
+			zs_write_reg(cs, 1, cs->cs_creg[1]);
+		}
+		if (zst->zst_tx_busy) {
+			zst->zst_tx_busy = 0;
+			zst->zst_tx_done = 1;
+			cs->cs_softreq = 1;
+		}
+	}
+}
+
+#ifdef DDB
+#include <ddb/db_var.h>
+#define	DB_CONSOLE	db_console
+#else
+#define	DB_CONSOLE	1
+#endif
+
+/*
+ * status change interrupt.  (splzs)
+ */
+void
+zstty_stint(cs, force)
+	struct zs_chanstate *cs;
+	int force;
+{
+	struct zstty_softc *zst = cs->cs_private;
+	u_char rr0, delta;
+
+	rr0 = zs_read_csr(cs);
+	zs_write_csr(cs, ZSWR0_RESET_STATUS);
+
+	/*
+	 * Check here for console break, so that we can abort
+	 * even when interrupts are locking up the machine.
+	 */
+	if ((zst->zst_hwflags & ZS_HWFLAG_CONSOLE_INPUT) &&
+	    ISSET(rr0, ZSRR0_BREAK) && DB_CONSOLE)
+		zs_abort(cs);
+
+	if (!force)
+		delta = rr0 ^ cs->cs_rr0;
+	else
+		delta = cs->cs_rr0_mask;
+	cs->cs_rr0 = rr0;
+
+	if (ISSET(delta, cs->cs_rr0_mask)) {
+		SET(cs->cs_rr0_delta, delta);
+
+		/*
+		 * Stop output immediately if we lose the output
+		 * flow control signal or carrier detect.
+		 */
+		if (ISSET(~rr0, cs->cs_rr0_mask)) {
+			zst->zst_tbc = 0;
+			zst->zst_heldtbc = 0;
+		}
+
+		zst->zst_st_check = 1;
+		cs->cs_softreq = 1;
+	}
+}
+
+void
+zstty_diag(arg)
+	void *arg;
+{
+	struct zstty_softc *zst = arg;
+	int overflows, floods;
+	int s;
+
+	s = splzs();
+	overflows = zst->zst_overflows;
+	zst->zst_overflows = 0;
+	floods = zst->zst_floods;
+	zst->zst_floods = 0;
+	zst->zst_errors = 0;
+	splx(s);
+
+	log(LOG_WARNING, "%s: %d silo overflow%s, %d ibuf flood%s\n",
+	    zst->zst_dev.dv_xname,
+	    overflows, overflows == 1 ? "" : "s",
+	    floods, floods == 1 ? "" : "s");
+}
+
+void
+zstty_rxsoft(zst, tp)
+	struct zstty_softc *zst;
+	struct tty *tp;
+{
+	struct zs_chanstate *cs = zst->zst_cs;
+	int (*rint)(int c, struct tty *tp) = linesw[tp->t_line].l_rint;
+	u_char *get, *end;
+	u_int cc, scc;
+	u_char rr1;
+	int code;
+	int s;
+
+	end = zst->zst_ebuf;
+	get = zst->zst_rbget;
+	scc = cc = zstty_rbuf_size - zst->zst_rbavail;
+
+	if (cc == zstty_rbuf_size) {
+		zst->zst_floods++;
+		if (zst->zst_errors++ == 0)
+			timeout_add(&zst->zst_diag_ch, 60 * hz);
+	}
+
+	/* If not yet open, drop the entire buffer content here */
+	if (!ISSET(tp->t_state, TS_ISOPEN)) {
+		get += cc << 1;
+		if (get >= end)
+			get -= zstty_rbuf_size << 1;
+		cc = 0;
+	}
+	while (cc) {
+		code = get[0];
+		rr1 = get[1];
+		if (ISSET(rr1, ZSRR1_DO | ZSRR1_FE | ZSRR1_PE)) {
+			if (ISSET(rr1, ZSRR1_DO)) {
+				zst->zst_overflows++;
+				if (zst->zst_errors++ == 0)
+					timeout_add(&zst->zst_diag_ch, 60 * hz);
+			}
+			if (ISSET(rr1, ZSRR1_FE))
+				SET(code, TTY_FE);
+			if (ISSET(rr1, ZSRR1_PE))
+				SET(code, TTY_PE);
+		}
+		if ((*rint)(code, tp) == -1) {
+			/*
+			 * The line discipline's buffer is out of space.
+			 */
+			if (!ISSET(zst->zst_rx_flags, RX_TTY_BLOCKED)) {
+				/*
+				 * We're either not using flow control, or the
+				 * line discipline didn't tell us to block for
+				 * some reason.  Either way, we have no way to
+				 * know when there's more space available, so
+				 * just drop the rest of the data.
+				 */
+				get += cc << 1;
+				if (get >= end)
+					get -= zstty_rbuf_size << 1;
+				cc = 0;
+			} else {
+				/*
+				 * Don't schedule any more receive processing
+				 * until the line discipline tells us there's
+				 * space available (through comhwiflow()).
+				 * Leave the rest of the data in the input
+				 * buffer.
+				 */
+				SET(zst->zst_rx_flags, RX_TTY_OVERFLOWED);
+			}
+			break;
+		}
+		get += 2;
+		if (get >= end)
+			get = zst->zst_rbuf;
+		cc--;
+	}
+
+	if (cc != scc) {
+		zst->zst_rbget = get;
+		s = splzs();
+		cc = zst->zst_rbavail += scc - cc;
+		/* Buffers should be ok again, release possible block. */
+		if (cc >= zst->zst_r_lowat) {
+			if (ISSET(zst->zst_rx_flags, RX_IBUF_OVERFLOWED)) {
+				CLR(zst->zst_rx_flags, RX_IBUF_OVERFLOWED);
+				SET(cs->cs_preg[1], ZSWR1_RIE);
+				cs->cs_creg[1] = cs->cs_preg[1];
+				zs_write_reg(cs, 1, cs->cs_creg[1]);
+			}
+			if (ISSET(zst->zst_rx_flags, RX_IBUF_BLOCKED)) {
+				CLR(zst->zst_rx_flags, RX_IBUF_BLOCKED);
+				zs_hwiflow(zst);
+			}
+		}
+		splx(s);
+	}
+}
+
+void
+zstty_txsoft(zst, tp)
+	struct zstty_softc *zst;
+	struct tty *tp;
+{
+
+	CLR(tp->t_state, TS_BUSY);
+	if (ISSET(tp->t_state, TS_FLUSH))
+		CLR(tp->t_state, TS_FLUSH);
+	else
+		ndflush(&tp->t_outq, (int)(zst->zst_tba - tp->t_outq.c_cf));
+	(*linesw[tp->t_line].l_start)(tp);
+}
+
+void
+zstty_stsoft(zst, tp)
+	struct zstty_softc *zst;
+	struct tty *tp;
+{
+	struct zs_chanstate *cs = zst->zst_cs;
+	u_char rr0, delta;
+	int s;
+
+	s = splzs();
+	rr0 = cs->cs_rr0;
+	delta = cs->cs_rr0_delta;
+	cs->cs_rr0_delta = 0;
+	splx(s);
+
+	if (ISSET(delta, cs->cs_rr0_dcd)) {
+		/*
+		 * Inform the tty layer that carrier detect changed.
+		 */
+		(void) (*linesw[tp->t_line].l_modem)(tp, ISSET(rr0, ZSRR0_DCD));
+	}
+
+	if (ISSET(delta, cs->cs_rr0_cts)) {
+		/* Block or unblock output according to flow control. */
+		if (ISSET(rr0, cs->cs_rr0_cts)) {
+			zst->zst_tx_stopped = 0;
+			(*linesw[tp->t_line].l_start)(tp);
+		} else {
+			zst->zst_tx_stopped = 1;
+		}
+	}
+}
+
+/*
+ * Software interrupt.  Called at zssoft
+ *
+ * The main job to be done here is to empty the input ring
+ * by passing its contents up to the tty layer.  The ring is
+ * always emptied during this operation, therefore the ring
+ * must not be larger than the space after "high water" in
+ * the tty layer, or the tty layer might drop our input.
+ *
+ * Note: an "input blockage" condition is assumed to exist if
+ * EITHER the TS_TBLOCK flag or zst_rx_blocked flag is set.
+ */
+void
+zstty_softint(cs)
+	struct zs_chanstate *cs;
+{
+	struct zstty_softc *zst = cs->cs_private;
+	struct tty *tp = zst->zst_tty;
+	int s;
+
+	s = spltty();
+
+	if (zst->zst_rx_ready) {
+		zst->zst_rx_ready = 0;
+		zstty_rxsoft(zst, tp);
+	}
+
+	if (zst->zst_st_check) {
+		zst->zst_st_check = 0;
+		zstty_stsoft(zst, tp);
+	}
+
+	if (zst->zst_tx_done) {
+		zst->zst_tx_done = 0;
+		zstty_txsoft(zst, tp);
+	}
+
+	splx(s);
+}
+
+struct zsops zsops_tty = {
+	zstty_rxint,	/* receive char available */
+	zstty_stint,	/* external/status */
+	zstty_txint,	/* xmit buffer empty */
+	zstty_softint,	/* process software interrupt */
+};