/*      $NetBSD: dhu.c,v 1.58 2022/10/26 23:46:37 riastradh 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 1.58 2022/10/26 23:46:37 riastradh 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;

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

        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;
        }
        ttyunlock(tp);
        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);
}