/*	$NetBSD: dhu.c,v 1.57 2014/07/25 08:10:38 dholland Exp $	*/
/*
 * Copyright (c) 2003, Hugh Graham.
 * Copyright (c) 1992, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Ralph Campbell and Rick Macklem.
 *
 * 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. 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.
 */

/*
 * Copyright (c) 1996  Ken C. Wellsch.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Ralph Campbell and Rick Macklem.
 *
 * 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.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: dhu.c,v 1.57 2014/07/25 08:10:38 dholland Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/ioctl.h>
#include <sys/tty.h>
#include <sys/proc.h>
#include <sys/buf.h>
#include <sys/conf.h>
#include <sys/file.h>
#include <sys/uio.h>
#include <sys/kernel.h>
#include <sys/syslog.h>
#include <sys/device.h>
#include <sys/kauth.h>

#include <sys/bus.h>
#include <machine/scb.h>

#include <dev/qbus/ubavar.h>

#include <dev/qbus/dhureg.h>

#include "ioconf.h"

/* A DHU-11 has 16 ports while a DHV-11 has only 8. We use 16 by default */

#define	NDHULINE	16

#define DHU_M2U(c)	((c)>>4)	/* convert minor(dev) to unit # */
#define DHU_LINE(u)	((u)&0xF)	/* extract line # from minor(dev) */

struct dhu_softc {
	device_t	sc_dev;		/* Device struct used by config */
	struct evcnt	sc_rintrcnt;	/* Interrupt statistics */
	struct evcnt	sc_tintrcnt;	/* Interrupt statistics */
	int		sc_type;	/* controller type, DHU or DHV */
	int		sc_lines;	/* number of lines */
	bus_space_tag_t	sc_iot;
	bus_space_handle_t sc_ioh;
	bus_dma_tag_t	sc_dmat;
	struct {
		struct	tty *dhu_tty;	/* what we work on */
		bus_dmamap_t dhu_dmah;
		int	dhu_state;	/* to manage TX output status */
		short	dhu_cc;		/* character count on TX */
		short	dhu_modem;	/* modem bits state */
	} sc_dhu[NDHULINE];
};

#define IS_DHU			16	/* Unibus DHU-11 board linecount */
#define IS_DHV			 8	/* Q-bus DHV-11 or DHQ-11 */

#define STATE_IDLE		000	/* no current output in progress */
#define STATE_DMA_RUNNING	001	/* DMA TX in progress */
#define STATE_DMA_STOPPED	002	/* DMA TX was aborted */
#define STATE_TX_ONE_CHAR	004	/* did a single char directly */

/* Flags used to monitor modem bits, make them understood outside driver */

#define DML_DTR		TIOCM_DTR
#define DML_RTS		TIOCM_RTS
#define DML_CTS		TIOCM_CTS
#define DML_DCD		TIOCM_CD
#define DML_RI		TIOCM_RI
#define DML_DSR		TIOCM_DSR
#define DML_BRK		0100000		/* no equivalent, we will mask */

#define DHU_READ_WORD(reg) \
	bus_space_read_2(sc->sc_iot, sc->sc_ioh, reg)
#define DHU_WRITE_WORD(reg, val) \
	bus_space_write_2(sc->sc_iot, sc->sc_ioh, reg, val)
#define DHU_READ_BYTE(reg) \
	bus_space_read_1(sc->sc_iot, sc->sc_ioh, reg)
#define DHU_WRITE_BYTE(reg, val) \
	bus_space_write_1(sc->sc_iot, sc->sc_ioh, reg, val)


/*  On a stock DHV, channel pairs (0/1, 2/3, etc.) must use */
/* a baud rate from the same group.  So limiting to B is likely */
/* best, although clone boards like the ABLE QHV allow all settings. */

static const struct speedtab dhuspeedtab[] = {
  {       0,	0		},	/* Groups  */
  {      50,	DHU_LPR_B50	},	/* A	   */
  {      75,	DHU_LPR_B75	},	/* 	 B */
  {     110,	DHU_LPR_B110	},	/* A and B */
  {     134,	DHU_LPR_B134	},	/* A and B */
  {     150,	DHU_LPR_B150	},	/* 	 B */
  {     300,	DHU_LPR_B300	},	/* A and B */
  {     600,	DHU_LPR_B600	},	/* A and B */
  {    1200,	DHU_LPR_B1200	},	/* A and B */
  {    1800,	DHU_LPR_B1800	},	/* 	 B */
  {    2000,	DHU_LPR_B2000	},	/* 	 B */
  {    2400,	DHU_LPR_B2400	},	/* A and B */
  {    4800,	DHU_LPR_B4800	},	/* A and B */
  {    7200,	DHU_LPR_B7200	},	/* A	   */
  {    9600,	DHU_LPR_B9600	},	/* A and B */
  {   19200,	DHU_LPR_B19200	},	/* 	 B */
  {   38400,	DHU_LPR_B38400	},	/* A	   */
  {      -1,	-1		}
};

static int	dhu_match(device_t, cfdata_t, void *);
static void	dhu_attach(device_t, device_t, void *);
static	void	dhurint(void *);
static	void	dhuxint(void *);
static	void	dhustart(struct tty *);
static	int	dhuparam(struct tty *, struct termios *);
static	int	dhuiflow(struct tty *, int);
static unsigned	dhumctl(struct dhu_softc *,int, int, int);

CFATTACH_DECL_NEW(dhu, sizeof(struct dhu_softc),
    dhu_match, dhu_attach, NULL, NULL);

static dev_type_open(dhuopen);
static dev_type_close(dhuclose);
static dev_type_read(dhuread);
static dev_type_write(dhuwrite);
static dev_type_ioctl(dhuioctl);
static dev_type_stop(dhustop);
static dev_type_tty(dhutty);
static dev_type_poll(dhupoll);

const struct cdevsw dhu_cdevsw = {
	.d_open = dhuopen,
	.d_close = dhuclose,
	.d_read = dhuread,
	.d_write = dhuwrite,
	.d_ioctl = dhuioctl,
	.d_stop = dhustop,
	.d_tty = dhutty,
	.d_poll = dhupoll,
	.d_mmap = nommap,
	.d_kqfilter = ttykqfilter,
	.d_discard = nodiscard,
	.d_flag = D_TTY
};

/* Autoconfig handles: setup the controller to interrupt, */
/* then complete the housecleaning for full operation */

static int
dhu_match(device_t parent, cfdata_t cf, void *aux)
{
	struct uba_attach_args *ua = aux;
	int n;

	/* Reset controller to initialize, enable TX/RX interrupts */
	/* to catch floating vector info elsewhere when completed */

	bus_space_write_2(ua->ua_iot, ua->ua_ioh, DHU_UBA_CSR,
	    DHU_CSR_MASTER_RESET | DHU_CSR_RXIE | DHU_CSR_TXIE);

	/* Now wait up to 3 seconds for self-test to complete. */

	for (n = 0; n < 300; n++) {
		DELAY(10000);
		if ((bus_space_read_2(ua->ua_iot, ua->ua_ioh, DHU_UBA_CSR) &
		    DHU_CSR_MASTER_RESET) == 0)
			break;
	}

	/* If the RESET did not clear after 3 seconds, */
	/* the controller must be broken. */

	if (n >= 300)
		return 0;

	/* Check whether diagnostic run has signalled a failure. */

	if ((bus_space_read_2(ua->ua_iot, ua->ua_ioh, DHU_UBA_CSR) &
	    DHU_CSR_DIAG_FAIL) != 0)
		return 0;

	return 1;
}

static void
dhu_attach(device_t parent, device_t self, void *aux)
{
	struct dhu_softc *sc = device_private(self);
	struct uba_attach_args *ua = aux;
	unsigned c;
	int n, i;

	sc->sc_dev = self;
	sc->sc_iot = ua->ua_iot;
	sc->sc_ioh = ua->ua_ioh;
	sc->sc_dmat = ua->ua_dmat;
	/* Process the 8 bytes of diagnostic info put into */
	/* the FIFO following the master reset operation. */

	aprint_normal("\n");
	for (n = 0; n < 8; n++) {
		c = DHU_READ_WORD(DHU_UBA_RBUF);

		if ((c&DHU_DIAG_CODE) == DHU_DIAG_CODE) {
			if ((c&0200) == 0000)
				aprint_error_dev(self, "rom(%d) version %d\n",
					((c>>1)&01), ((c>>2)&037));
			else if (((c>>2)&07) != 0)
				aprint_error_dev(self, "diag-error(proc%d)=%x\n",
					((c>>1)&01), ((c>>2)&07));
		}
	}

	c = DHU_READ_WORD(DHU_UBA_STAT);

	sc->sc_type = (c & DHU_STAT_DHU)? IS_DHU: IS_DHV;

	sc->sc_lines = 8;	/* default */
	if (sc->sc_type == IS_DHU && (c & DHU_STAT_MDL))
		sc->sc_lines = 16;

	aprint_normal_dev(self, "DH%s-11\n",
	    sc->sc_type == IS_DHU ? "U" : "V");

	for (i = 0; i < sc->sc_lines; i++) {
		struct tty *tp;

		tp = sc->sc_dhu[i].dhu_tty = tty_alloc();
		sc->sc_dhu[i].dhu_state = STATE_IDLE;
		bus_dmamap_create(sc->sc_dmat, tp->t_outq.c_cn, 1,
		    tp->t_outq.c_cn, 0, BUS_DMA_ALLOCNOW|BUS_DMA_NOWAIT,
		    &sc->sc_dhu[i].dhu_dmah);
		bus_dmamap_load(sc->sc_dmat, sc->sc_dhu[i].dhu_dmah,
		    tp->t_outq.c_cs, tp->t_outq.c_cn, 0, BUS_DMA_NOWAIT);

	}

	/* Now establish RX & TX interrupt handlers */

	uba_intr_establish(ua->ua_icookie, ua->ua_cvec,
		dhurint, sc, &sc->sc_rintrcnt);
	uba_intr_establish(ua->ua_icookie, ua->ua_cvec + 4,
		dhuxint, sc, &sc->sc_tintrcnt);
	evcnt_attach_dynamic(&sc->sc_rintrcnt, EVCNT_TYPE_INTR, ua->ua_evcnt,
		device_xname(sc->sc_dev), "rintr");
	evcnt_attach_dynamic(&sc->sc_tintrcnt, EVCNT_TYPE_INTR, ua->ua_evcnt,
		device_xname(sc->sc_dev), "tintr");
}

/* Receiver Interrupt */

static void
dhurint(void *arg)
{
	struct dhu_softc *sc = arg;
	struct tty *tp;
	int cc, line;
	unsigned c, delta;
	int overrun = 0;

	while ((c = DHU_READ_WORD(DHU_UBA_RBUF)) & DHU_RBUF_DATA_VALID) {

		/* Ignore diagnostic FIFO entries. */

		if ((c & DHU_DIAG_CODE) == DHU_DIAG_CODE)
			continue;

		cc = c & 0xFF;
		line = DHU_LINE(c>>8);
		tp = sc->sc_dhu[line].dhu_tty;

		/* LINK.TYPE is set so we get modem control FIFO entries */

		if ((c & DHU_DIAG_CODE) == DHU_MODEM_CODE) {
			c = (c << 8);
			/* Do MDMBUF flow control, wakeup sleeping opens */
			if (c & DHU_STAT_DCD) {
				if (!(tp->t_state & TS_CARR_ON))
				    (void)(*tp->t_linesw->l_modem)(tp, 1);
			}
			else if ((tp->t_state & TS_CARR_ON) &&
				(*tp->t_linesw->l_modem)(tp, 0) == 0)
					(void) dhumctl(sc, line, 0, DMSET);

			/* Do CRTSCTS flow control */
			delta = c ^ sc->sc_dhu[line].dhu_modem;
			sc->sc_dhu[line].dhu_modem = c;
			if ((delta & DHU_STAT_CTS) &&
			    (tp->t_state & TS_ISOPEN) &&
			    (tp->t_cflag & CRTSCTS)) {
				if (c & DHU_STAT_CTS) {
					tp->t_state &= ~TS_TTSTOP;
					ttstart(tp);
				} else {
					tp->t_state |= TS_TTSTOP;
					dhustop(tp, 0);
				}
			}
			continue;
		}

		if (!(tp->t_state & TS_ISOPEN)) {
			cv_broadcast(&tp->t_rawcv);
			continue;
		}

		if ((c & DHU_RBUF_OVERRUN_ERR) && overrun == 0) {
			log(LOG_WARNING, "%s: silo overflow, line %d\n",
				device_xname(sc->sc_dev), line);
			overrun = 1;
		}
		/* A BREAK key will appear as a NULL with a framing error */
		if (c & DHU_RBUF_FRAMING_ERR)
			cc |= TTY_FE;
		if (c & DHU_RBUF_PARITY_ERR)
			cc |= TTY_PE;

		(*tp->t_linesw->l_rint)(cc, tp);
	}
}

/* Transmitter Interrupt */

static void
dhuxint(void *arg)
{
	struct dhu_softc *sc = arg;
	struct tty *tp;
	int line, i;

	while ((i = DHU_READ_BYTE(DHU_UBA_CSR_HI)) & (DHU_CSR_TX_ACTION >> 8)) {

		line = DHU_LINE(i);
		tp = sc->sc_dhu[line].dhu_tty;

		if (i & (DHU_CSR_TX_DMA_ERROR >> 8))
			printf("%s: DMA ERROR on line: %d\n",
			    device_xname(sc->sc_dev), line);
		if (i & (DHU_CSR_DIAG_FAIL >> 8))
			printf("%s: DIAG FAIL on line: %d\n",
			    device_xname(sc->sc_dev), line);

		tp->t_state &= ~TS_BUSY;
		if (tp->t_state & TS_FLUSH)
			tp->t_state &= ~TS_FLUSH;
		else {
			if (sc->sc_dhu[line].dhu_state == STATE_DMA_STOPPED)
				sc->sc_dhu[line].dhu_cc -=
				    DHU_READ_WORD(DHU_UBA_TBUFCNT);
			ndflush(&tp->t_outq, sc->sc_dhu[line].dhu_cc);
			sc->sc_dhu[line].dhu_cc = 0;
		}

		sc->sc_dhu[line].dhu_state = STATE_IDLE;

		(*tp->t_linesw->l_start)(tp);
	}
}

int
dhuopen(dev_t dev, int flag, int mode, struct lwp *l)
{
	struct tty *tp;
	int unit, line;
	struct dhu_softc *sc;
	int error = 0;

	unit = DHU_M2U(minor(dev));
	line = DHU_LINE(minor(dev));

	sc = device_lookup_private(&dhu_cd, unit);
	if (!sc)
		return (ENXIO);

	if (line >= sc->sc_lines)
		return ENXIO;

	mutex_spin_enter(&tty_lock);
	if (sc->sc_type == IS_DHU) {
		/* CSR 3:0 must be 0 */
		DHU_WRITE_BYTE(DHU_UBA_CSR, DHU_CSR_RXIE);
		/* RX int delay 10ms */
		DHU_WRITE_BYTE(DHU_UBA_RXTIME, 10);
	}
	DHU_WRITE_BYTE(DHU_UBA_CSR, DHU_CSR_RXIE | line);
	sc->sc_dhu[line].dhu_modem = DHU_READ_WORD(DHU_UBA_STAT);

	tp = sc->sc_dhu[line].dhu_tty;

	if (kauth_authorize_device_tty(l->l_cred, KAUTH_DEVICE_TTY_OPEN, tp))
		return (EBUSY);

	tp->t_oproc   = dhustart;
	tp->t_param   = dhuparam;
	tp->t_hwiflow = dhuiflow;
	tp->t_dev = dev;

	if ((tp->t_state & TS_ISOPEN) == 0) {
		ttychars(tp);
		if (tp->t_ispeed == 0) {
			tp->t_iflag = TTYDEF_IFLAG;
			tp->t_oflag = TTYDEF_OFLAG;
			tp->t_cflag = TTYDEF_CFLAG;
			tp->t_lflag = TTYDEF_LFLAG;
			tp->t_ispeed = tp->t_ospeed = TTYDEF_SPEED;
		}
		(void) dhuparam(tp, &tp->t_termios);
		ttsetwater(tp);
	}
	/* Use DMBIS and *not* DMSET or else we clobber incoming bits */
	if (dhumctl(sc, line, DML_DTR|DML_RTS, DMBIS) & DML_DCD)
		tp->t_state |= TS_CARR_ON;
	while (!(flag & O_NONBLOCK) && !(tp->t_cflag & CLOCAL) &&
	    !(tp->t_state & TS_CARR_ON)) {
		tp->t_wopen++;
		error = ttysleep(tp, &tp->t_rawcv, true, 0);
		tp->t_wopen--;
		if (error)
			break;
	}
	mutex_spin_exit(&tty_lock);
	if (error)
		return (error);
	return ((*tp->t_linesw->l_open)(dev, tp));
}

/*ARGSUSED*/
int
dhuclose(dev_t dev, int flag, int mode, struct lwp *l)
{
	const int unit = DHU_M2U(minor(dev));
	const int line = DHU_LINE(minor(dev));
	struct dhu_softc *sc = device_lookup_private(&dhu_cd, unit);
	struct tty *tp = sc->sc_dhu[line].dhu_tty;

	(*tp->t_linesw->l_close)(tp, flag);

	/* Make sure a BREAK state is not left enabled. */

	(void) dhumctl(sc, line, DML_BRK, DMBIC);

	/* Do a hangup if so required. */

	if ((tp->t_cflag & HUPCL) || tp->t_wopen || !(tp->t_state & TS_ISOPEN))
		(void) dhumctl(sc, line, 0, DMSET);

	return (ttyclose(tp));
}

int
dhuread(dev_t dev, struct uio *uio, int flag)
{
	struct dhu_softc *sc = device_lookup_private(&dhu_cd, DHU_M2U(minor(dev)));
	struct tty *tp = sc->sc_dhu[DHU_LINE(minor(dev))].dhu_tty;

	return ((*tp->t_linesw->l_read)(tp, uio, flag));
}

int
dhuwrite(dev_t dev, struct uio *uio, int flag)
{
	struct dhu_softc *sc = device_lookup_private(&dhu_cd, DHU_M2U(minor(dev)));
	struct tty *tp = sc->sc_dhu[DHU_LINE(minor(dev))].dhu_tty;

	return ((*tp->t_linesw->l_write)(tp, uio, flag));
}

int
dhupoll(dev_t dev, int events, struct lwp *l)
{
	struct dhu_softc *sc = device_lookup_private(&dhu_cd, DHU_M2U(minor(dev)));
	struct tty *tp = sc->sc_dhu[DHU_LINE(minor(dev))].dhu_tty;

	return ((*tp->t_linesw->l_poll)(tp, events, l));
}

/*ARGSUSED*/
int
dhuioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
{
	const int unit = DHU_M2U(minor(dev));
	const int line = DHU_LINE(minor(dev));
	struct dhu_softc *sc = device_lookup_private(&dhu_cd, unit);
	struct tty *tp = sc->sc_dhu[line].dhu_tty;
	int error;

	error = (*tp->t_linesw->l_ioctl)(tp, cmd, data, flag, l);
	if (error != EPASSTHROUGH)
		return (error);

	error = ttioctl(tp, cmd, data, flag, l);
	if (error != EPASSTHROUGH)
		return (error);

	switch (cmd) {

	case TIOCSBRK:
		(void) dhumctl(sc, line, DML_BRK, DMBIS);
		break;

	case TIOCCBRK:
		(void) dhumctl(sc, line, DML_BRK, DMBIC);
		break;

	case TIOCSDTR:
		(void) dhumctl(sc, line, DML_DTR|DML_RTS, DMBIS);
		break;

	case TIOCCDTR:
		(void) dhumctl(sc, line, DML_DTR|DML_RTS, DMBIC);
		break;

	case TIOCMSET:
		(void) dhumctl(sc, line, *(int *)data, DMSET);
		break;

	case TIOCMBIS:
		(void) dhumctl(sc, line, *(int *)data, DMBIS);
		break;

	case TIOCMBIC:
		(void) dhumctl(sc, line, *(int *)data, DMBIC);
		break;

	case TIOCMGET:
		*(int *)data = (dhumctl(sc, line, 0, DMGET) & ~DML_BRK);
		break;

	default:
		return (EPASSTHROUGH);
	}
	return (0);
}

struct tty *
dhutty(dev_t dev)
{
	struct dhu_softc *sc = device_lookup_private(&dhu_cd, DHU_M2U(minor(dev)));

	return sc->sc_dhu[DHU_LINE(minor(dev))].dhu_tty;
}

/*ARGSUSED*/
void
dhustop(struct tty *tp, int flag)
{
	int s;

	s = spltty();

	if (tp->t_state & TS_BUSY) {
		const int unit = DHU_M2U(minor(tp->t_dev));
		const int line = DHU_LINE(minor(tp->t_dev));
		struct dhu_softc *sc = device_lookup_private(&dhu_cd, unit);

		if (sc->sc_dhu[line].dhu_state == STATE_DMA_RUNNING) {

			sc->sc_dhu[line].dhu_state = STATE_DMA_STOPPED;

			DHU_WRITE_BYTE(DHU_UBA_CSR, DHU_CSR_RXIE | line);
			DHU_WRITE_WORD(DHU_UBA_LNCTRL,
			    DHU_READ_WORD(DHU_UBA_LNCTRL) |
			    DHU_LNCTRL_DMA_ABORT);
		}

		if (!(tp->t_state & TS_TTSTOP))
			tp->t_state |= TS_FLUSH;
	}
	(void) splx(s);
}

static void
dhustart(struct tty *tp)
{
	struct dhu_softc *sc;
	int line, cc;
	int addr;
	int s;

	s = spltty();
	if (tp->t_state & (TS_TIMEOUT|TS_BUSY|TS_TTSTOP))
		goto out;
	if (!ttypull(tp))
		goto out;
	cc = ndqb(&tp->t_outq, 0);
	if (cc == 0)
		goto out;

	tp->t_state |= TS_BUSY;

	sc = device_lookup_private(&dhu_cd,DHU_M2U(minor(tp->t_dev)));

	line = DHU_LINE(minor(tp->t_dev));

	DHU_WRITE_BYTE(DHU_UBA_CSR, DHU_CSR_RXIE | line);

	sc->sc_dhu[line].dhu_cc = cc;

	if (cc == 1 && sc->sc_type == IS_DHV) {

		sc->sc_dhu[line].dhu_state = STATE_TX_ONE_CHAR;

		DHU_WRITE_WORD(DHU_UBA_TXCHAR,
		    DHU_TXCHAR_DATA_VALID | *tp->t_outq.c_cf);

	} else {

		sc->sc_dhu[line].dhu_state = STATE_DMA_RUNNING;

		addr = sc->sc_dhu[line].dhu_dmah->dm_segs[0].ds_addr +
			(tp->t_outq.c_cf - tp->t_outq.c_cs);

		DHU_WRITE_WORD(DHU_UBA_TBUFCNT, cc);
		DHU_WRITE_WORD(DHU_UBA_TBUFAD1, addr & 0xFFFF);
		DHU_WRITE_WORD(DHU_UBA_TBUFAD2, ((addr>>16) & 0x3F) |
		    DHU_TBUFAD2_TX_ENABLE);
		DHU_WRITE_WORD(DHU_UBA_LNCTRL,
		    DHU_READ_WORD(DHU_UBA_LNCTRL) & ~DHU_LNCTRL_DMA_ABORT);
		DHU_WRITE_WORD(DHU_UBA_TBUFAD2,
		    DHU_READ_WORD(DHU_UBA_TBUFAD2) | DHU_TBUFAD2_DMA_START);
	}
out:
	(void) splx(s);
	return;
}

static int
dhuparam(struct tty *tp, struct termios *t)
{
	int cflag = t->c_cflag;
	int ispeed = ttspeedtab(t->c_ispeed, dhuspeedtab);
	int ospeed = ttspeedtab(t->c_ospeed, dhuspeedtab);
	unsigned int lpr;
	unsigned int lnctrl;
	const int unit = DHU_M2U(minor(tp->t_dev));
	const int line = DHU_LINE(minor(tp->t_dev));
	struct dhu_softc * const sc = device_lookup_private(&dhu_cd, unit);
	int s;


	/* check requested parameters */
	if (ospeed < 0 || ispeed < 0)
		return (EINVAL);

	tp->t_ispeed = t->c_ispeed;
	tp->t_ospeed = t->c_ospeed;
	tp->t_cflag = cflag;

	if (ospeed == 0) {
		(void) dhumctl(sc, line, 0, DMSET);	/* hang up line */
		return (0);
	}

	s = spltty();
	DHU_WRITE_BYTE(DHU_UBA_CSR, DHU_CSR_RXIE | line);

	lpr = ((ispeed&017)<<8) | ((ospeed&017)<<12) ;

	switch (cflag & CSIZE) {

	case CS5:
		lpr |= DHU_LPR_5_BIT_CHAR;
		break;

	case CS6:
		lpr |= DHU_LPR_6_BIT_CHAR;
		break;

	case CS7:
		lpr |= DHU_LPR_7_BIT_CHAR;
		break;

	default:
		lpr |= DHU_LPR_8_BIT_CHAR;
		break;
	}

	if (cflag & PARENB)
		lpr |= DHU_LPR_PARENB;
	if (!(cflag & PARODD))
		lpr |= DHU_LPR_EPAR;
	if (cflag & CSTOPB)
		lpr |= DHU_LPR_2_STOP;

	DHU_WRITE_WORD(DHU_UBA_LPR, lpr);

	DHU_WRITE_WORD(DHU_UBA_TBUFAD2,
	    DHU_READ_WORD(DHU_UBA_TBUFAD2) | DHU_TBUFAD2_TX_ENABLE);

	lnctrl = DHU_READ_WORD(DHU_UBA_LNCTRL);

	/* Setting LINK.TYPE enables modem signal change interrupts. */

	lnctrl |= (DHU_LNCTRL_RX_ENABLE | DHU_LNCTRL_LINK_TYPE);

	/* Enable the auto XON/XOFF feature on the controller */

	if (t->c_iflag & IXON)
		lnctrl |= DHU_LNCTRL_OAUTO;
	else
		lnctrl &= ~DHU_LNCTRL_OAUTO;

	if (t->c_iflag & IXOFF)
		lnctrl |= DHU_LNCTRL_IAUTO;
	else
		lnctrl &= ~DHU_LNCTRL_IAUTO;

	DHU_WRITE_WORD(DHU_UBA_LNCTRL, lnctrl);

	(void) splx(s);
	return (0);
}

static int
dhuiflow(struct tty *tp, int flag)
{

	if (tp->t_cflag & CRTSCTS) {
		const int unit = DHU_M2U(minor(tp->t_dev));
		const int line = DHU_LINE(minor(tp->t_dev));
		struct dhu_softc * const sc = device_lookup_private(&dhu_cd, unit);
		(void) dhumctl(sc, line, DML_RTS, ((flag)? DMBIC: DMBIS));
		return (1);
	}
	return (0);
}

static unsigned int
dhumctl(struct dhu_softc *sc, int line, int bits, int how)
{
	unsigned status;
	unsigned lnctrl;
	unsigned mbits;
	int s;

	s = spltty();

	DHU_WRITE_BYTE(DHU_UBA_CSR, DHU_CSR_RXIE | line);

	mbits = 0;

	/* external signals as seen from the port */

	status = DHU_READ_WORD(DHU_UBA_STAT);

	if (status & DHU_STAT_CTS)
		mbits |= DML_CTS;

	if (status & DHU_STAT_DCD)
		mbits |= DML_DCD;

	if (status & DHU_STAT_DSR)
		mbits |= DML_DSR;

	if (status & DHU_STAT_RI)
		mbits |= DML_RI;

	/* internal signals/state delivered to port */

	lnctrl = DHU_READ_WORD(DHU_UBA_LNCTRL);

	if (lnctrl & DHU_LNCTRL_RTS)
		mbits |= DML_RTS;

	if (lnctrl & DHU_LNCTRL_DTR)
		mbits |= DML_DTR;

	if (lnctrl & DHU_LNCTRL_BREAK)
		mbits |= DML_BRK;

	switch (how) {

	case DMSET:
		mbits = bits;
		break;

	case DMBIS:
		mbits |= bits;
		break;

	case DMBIC:
		mbits &= ~bits;
		break;

	case DMGET:
		(void) splx(s);
		return (mbits);
	}

	if (mbits & DML_RTS)
		lnctrl |= DHU_LNCTRL_RTS;
	else
		lnctrl &= ~DHU_LNCTRL_RTS;

	if (mbits & DML_DTR)
		lnctrl |= DHU_LNCTRL_DTR;
	else
		lnctrl &= ~DHU_LNCTRL_DTR;

	if (mbits & DML_BRK)
		lnctrl |= DHU_LNCTRL_BREAK;
	else
		lnctrl &= ~DHU_LNCTRL_BREAK;

	DHU_WRITE_WORD(DHU_UBA_LNCTRL, lnctrl);

	(void) splx(s);
	return (mbits);
}