/*      $NetBSD: cd18xx.c,v 1.33 2024/06/02 13:28:44 andvar Exp $       */

/*
* Copyright (c) 1998, 2001 Matthew R. Green
* 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.
*
* 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) 1998, 1999 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Charles M. Hannum.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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) 1991 The Regents of the University of California.
* 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. 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.
*
*      @(#)com.c       7.5 (Berkeley) 5/16/91
*/

/*
* cirrus logic CL-CD180/CD1864/CD1865 driver, based in (large) parts on
* the com and z8530 drivers.  thanks charles.
*/

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: cd18xx.c,v 1.33 2024/06/02 13:28:44 andvar Exp $");

#include <sys/param.h>
#include <sys/conf.h>
#include <sys/device.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/proc.h>
#include <sys/kernel.h>
#include <sys/tty.h>
#include <sys/fcntl.h>
#include <sys/kauth.h>
#include <sys/intr.h>

#include <sys/bus.h>

#include <dev/ic/cd18xxvar.h>
#include <dev/ic/cd18xxreg.h>

#include "ioconf.h"

/*
* some helpers
*/

static void     cdtty_attach(struct cd18xx_softc *, int);

static inline void cd18xx_rint(struct cd18xx_softc *, int *);
static inline void cd18xx_tint(struct cd18xx_softc *, int *);
static inline void cd18xx_mint(struct cd18xx_softc *, int *);

void cdtty_rxsoft(struct cd18xx_softc *, struct cdtty_port *, struct tty *);
void cdtty_txsoft(struct cd18xx_softc *, struct cdtty_port *, struct tty *);
void cdtty_stsoft(struct cd18xx_softc *, struct cdtty_port *, struct tty *);
void cd18xx_softintr(void *);

dev_type_open(cdttyopen);
dev_type_close(cdttyclose);
dev_type_read(cdttyread);
dev_type_write(cdttywrite);
dev_type_ioctl(cdttyioctl);
dev_type_stop(cdttystop);
dev_type_tty(cdttytty);
dev_type_poll(cdttypoll);

const struct cdevsw cdtty_cdevsw = {
       .d_open = cdttyopen,
       .d_close = cdttyclose,
       .d_read = cdttyread,
       .d_write = cdttywrite,
       .d_ioctl = cdttyioctl,
       .d_stop = cdttystop,
       .d_tty = cdttytty,
       .d_poll = cdttypoll,
       .d_mmap = nommap,
       .d_kqfilter = ttykqfilter,
       .d_discard = nodiscard,
       .d_flag = D_TTY
};

static void     cdtty_shutdown(struct cd18xx_softc *, struct cdtty_port *);
static void     cdttystart(struct tty *);
static int      cdttyparam(struct tty *, struct termios *);
static void     cdtty_break(struct cd18xx_softc *, struct cdtty_port *, int);
static void     cdtty_modem(struct cd18xx_softc *, struct cdtty_port *, int);
static int      cdttyhwiflow(struct tty *, int);
static void     cdtty_hwiflow(struct cd18xx_softc *, struct cdtty_port *);

static void     cdtty_loadchannelregs(struct cd18xx_softc *,
                                          struct cdtty_port *);

/* default read buffer size */
u_int cdtty_rbuf_size = CDTTY_RING_SIZE;

/* Stop input when 3/4 of the ring is full; restart when only 1/4 is full. */
u_int cdtty_rbuf_hiwat = (CDTTY_RING_SIZE * 1) / 4;
u_int cdtty_rbuf_lowat = (CDTTY_RING_SIZE * 3) / 4;

#define CD18XXDEBUG
#ifdef CD18XXDEBUG
#define CDD_INFO        0x0001
#define CDD_INTR        0x0002
int cd18xx_debug = CDD_INTR|CDD_INFO;
# define DPRINTF(l, x)  if (cd18xx_debug & l) printf x
#else
# define DPRINTF(l, x)  /* nothing */
#endif

/* Known supported revisions. */
struct cd18xx_revs {
       u_char          revision;
       u_char          onehundred_pin;
       const char      *name;
} cd18xx_revs[] = {
       { CD180_GFRCR_REV_B,            0, "CL-CD180 rev. B" },
       { CD180_GFRCR_REV_C,            0, "CL-CD180 rev. C" },
       { CD1864_GFRCR_REVISION_A,      1, "CL-CD1864 rev. A" },
       { CD1865_GFRCR_REVISION_A,      1, "CL-CD1865 rev. A" },
       { CD1865_GFRCR_REVISION_B,      1, "CL-CD1865 rev. B" },
       { CD1865_GFRCR_REVISION_C,      1, "CL-CD1865 rev. C" },
       { 0, 0, 0 }
};

/* wait for the CCR to go to zero */
static inline int cd18xx_wait_ccr(struct cd18xx_softc *);
static inline int
cd18xx_wait_ccr(struct cd18xx_softc *sc)
{
       int i = 100000;

       while (--i &&
           bus_space_read_1(sc->sc_tag, sc->sc_handle, CD18xx_CCR) != 0)
               ;
       return (i == 0);
}

/*
* device attach routine, high-end portion
*/
void
cd18xx_attach(struct cd18xx_softc *sc)
{
       static int chip_id_next = 1;
       int onehundred_pin, revision, i, port;

       /* read and print the revision */
       revision = cd18xx_read(sc, CD18xx_GFRCR);
       onehundred_pin = ISSET(cd18xx_read(sc, CD18xx_SRCR),CD18xx_SRCR_PKGTYP);
       for (i = 0; cd18xx_revs[i].name; i++)
               if (revision == cd18xx_revs[i].revision ||
                   onehundred_pin == cd18xx_revs[i].onehundred_pin) {
                       printf(": %s", cd18xx_revs[i].name);
                       break;
               }

       if (cd18xx_revs[i].name == NULL) {
               aprint_error_dev(sc->sc_dev, "unknown revision, bailing.\n");
               return;
       }

       /* prepare for reset */
       cd18xx_set_car(sc, 0);
       cd18xx_write(sc, CD18xx_GSVR, CD18xx_GSVR_CLEAR);

       /* wait for CCR to go to zero */
       if (cd18xx_wait_ccr(sc)) {
               printf("cd18xx_attach: reset change command timed out\n");
               return;
       }

       /* full reset of all channels */
       cd18xx_write(sc, CD18xx_CCR,
           CD18xx_CCR_RESET|CD18xx_CCR_RESET_HARD);

       /* loop until the GSVR is ready */
       i = 100000;
       while (--i && cd18xx_read(sc, CD18xx_GSVR) == CD18xx_GSVR_READY)
               ;
       if (i == 0) {
               aprint_normal("\n");
               aprint_error_dev(sc->sc_dev, "did not reset!\n");
               return;
       }

       /* write the chip_id */
       sc->sc_chip_id = chip_id_next++;
#ifdef DIAGNOSTIC
       if (sc->sc_chip_id > 31)
               panic("more than 31 cd18xx's?  help.");
#endif
       cd18xx_write(sc, CD18xx_GSVR, CD18xx_GSVR_SETID(sc));

       /* rx/tx/modem service match vectors, initialised by higher level */
       cd18xx_write(sc, CD18xx_MSMR, sc->sc_msmr | 0x80);
       cd18xx_write(sc, CD18xx_TSMR, sc->sc_tsmr | 0x80);
       cd18xx_write(sc, CD18xx_RSMR, sc->sc_rsmr | 0x80);

       printf(", gsvr %x msmr %x tsmr %x rsmr %x",
           cd18xx_read(sc, CD18xx_GSVR),
           cd18xx_read(sc, CD18xx_MSMR),
           cd18xx_read(sc, CD18xx_TSMR),
           cd18xx_read(sc, CD18xx_RSMR));

       /* prescale registers */
       sc->sc_pprh = 0xf0;
       sc->sc_pprl = 0;
       cd18xx_write(sc, CD18xx_PPRH, sc->sc_pprh);
       cd18xx_write(sc, CD18xx_PPRL, sc->sc_pprl);

       /* establish our soft interrupt. */
       sc->sc_si = softint_establish(SOFTINT_SERIAL, cd18xx_softintr, sc);

       printf(", 8 ports ready (chip id %d)\n", sc->sc_chip_id);

       /*
        * finally, we loop over all 8 channels initialising them
        */
       for (port = 0; port < 8; port++)
               cdtty_attach(sc, port);
}

/* tty portion of the code */

/*
* tty portion attach routine
*/
void
cdtty_attach(struct cd18xx_softc *sc, int port)
{
       struct cdtty_port *p = &sc->sc_ports[port];

       /* load CAR with channel number */
       cd18xx_set_car(sc, port);

       /* wait for CCR to go to zero */
       if (cd18xx_wait_ccr(sc)) {
               printf("cd18xx_attach: change command timed out setting "
                      "CAR for port %d\n", port);
               return;
       }

       /* set the RPTR to (arbitrary) 8 */
       cd18xx_write(sc, CD18xx_RTPR, 8);

       /* reset the modem signal value register */
       sc->sc_ports[port].p_msvr = CD18xx_MSVR_RESET;

       /* zero the service request enable register */
       cd18xx_write(sc, CD18xx_SRER, 0);

       /* enable the transmitter & receiver */
       SET(p->p_chanctl, CD18xx_CCR_CHANCTL |
                         CD18xx_CCR_CHANCTL_TxEN |
                         CD18xx_CCR_CHANCTL_RxEN);

       /* XXX no console or kgdb support yet! */

       /* get a tty structure */
       p->p_tty = tty_alloc();
       p->p_tty->t_oproc = cdttystart;
       p->p_tty->t_param = cdttyparam;
       p->p_tty->t_hwiflow = cdttyhwiflow;

       p->p_rbuf = malloc(cdtty_rbuf_size << 1, M_DEVBUF, M_WAITOK);
       p->p_rbput = p->p_rbget = p->p_rbuf;
       p->p_rbavail = cdtty_rbuf_size;
       if (p->p_rbuf == NULL) {
               aprint_error_dev(sc->sc_dev, "unable to allocate ring buffer for tty %d\n", port);
               return;
       }
       p->p_ebuf = p->p_rbuf + (cdtty_rbuf_size << 1);

       tty_attach(p->p_tty);
}

/*
* cdtty_shutdown: called when the device is last closed.
*/
void
cdtty_shutdown(struct cd18xx_softc *sc, struct cdtty_port *p)
{
       struct tty *tp = p->p_tty;
       int s;

       s = splserial();

       /* If we were asserting flow control, then deassert it. */
       SET(p->p_rx_flags, RX_IBUF_BLOCKED);
       cdtty_hwiflow(sc, p);

       /* Clear any break condition set with TIOCSBRK. */
       cdtty_break(sc, p, 0);

       /*
        * Hang up if necessary.  Wait a bit, so the other side has time to
        * notice even if we immediately open the port again.
        * Avoid tsleeping above splhigh().
        */
       if (ISSET(tp->t_cflag, HUPCL)) {
               cdtty_modem(sc, p, 0);
               splx(s);
               /* XXX tsleep will only timeout */
               (void) tsleep(sc, TTIPRI, ttclos, hz);
               s = splserial();
       }

       /* Turn off interrupts. */
       p->p_srer = 0;
       cd18xx_write(sc, CD18xx_SRER, p->p_srer);

       splx(s);
}

/*
* cdttyopen:  open syscall for cdtty terminals..
*/
int
cdttyopen(dev_t dev, int flag, int mode, struct lwp *l)
{
       struct tty *tp;
       struct cd18xx_softc *sc;
       struct cdtty_port *port;
       int channel, instance, s, error;

       channel = CD18XX_CHANNEL(dev);
       instance = CD18XX_INSTANCE(dev);

       /* ensure instance is valid */
       if (instance >= clcd_cd.cd_ndevs)
               return (ENXIO);

       /* get softc and port */
       sc = device_lookup_private(&clcd_cd, instance);
       if (sc == NULL)
               return (ENXIO);
       port = &sc->sc_ports[channel];
       if (port == NULL || port->p_rbuf == NULL)
               return (ENXIO);

       /* kgdb support?  maybe later... */

       tp = port->p_tty;

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

       s = spltty();

       /*
        * Do the following iff this is a first open.
        */
       if (!ISSET(tp->t_state, TS_ISOPEN) && tp->t_wopen == 0) {
               struct termios t;

               /* set up things in tp as necessary */
               tp->t_dev = dev;

               /*
                * Initialize the termios status to the defaults.  Add in the
                * sticky bits from TIOCSFLAGS.
                */
               t.c_ispeed = 0;
               t.c_ospeed = TTYDEF_SPEED;
               t.c_cflag = TTYDEF_CFLAG;

               if (ISSET(port->p_swflags, TIOCFLAG_CLOCAL))
                       SET(t.c_cflag, CLOCAL);
               if (ISSET(port->p_swflags, TIOCFLAG_CRTSCTS))
                       SET(t.c_cflag, CRTSCTS);
               if (ISSET(port->p_swflags, TIOCFLAG_CDTRCTS))
                       SET(t.c_cflag, CDTRCTS);
               if (ISSET(port->p_swflags, TIOCFLAG_MDMBUF))
                       SET(t.c_cflag, MDMBUF);

               /* Make sure param will see changes. */
               tp->t_ospeed = 0;       /* XXX set above ignored? */
               (void)cdttyparam(tp, &t);

               tp->t_iflag = TTYDEF_IFLAG;
               tp->t_oflag = TTYDEF_OFLAG;
               tp->t_lflag = TTYDEF_LFLAG;
               ttychars(tp);
               ttsetwater(tp);

               (void)splserial();

               /* turn on rx and modem interrupts */
               cd18xx_set_car(sc, CD18XX_CHANNEL(dev));
               SET(port->p_srer, CD18xx_SRER_Rx |
                                 CD18xx_SRER_RxSC |
                                 CD18xx_SRER_CD);
               cd18xx_write(sc, CD18xx_SRER, port->p_srer);

               /* always turn on DTR when open */
               cdtty_modem(sc, port, 1);

               /* initialise ring buffer */
               port->p_rbget = port->p_rbput = port->p_rbuf;
               port->p_rbavail = cdtty_rbuf_size;
               CLR(port->p_rx_flags, RX_ANY_BLOCK);
               cdtty_hwiflow(sc, port);
       }

       /* drop spl back before going into the line open */
       splx(s);

       error = ttyopen(tp, CD18XX_DIALOUT(dev), ISSET(flag, O_NONBLOCK));
       if (error == 0)
               error = (*tp->t_linesw->l_open)(dev, tp);

       return (error);
}

/*
* cdttyclose:  close syscall for cdtty terminals..
*/
int
cdttyclose(dev_t dev, int flag, int mode, struct lwp *l)
{
       struct cd18xx_softc *sc;
       struct cdtty_port *port;
       struct tty *tp;
       int channel, instance;

       channel = CD18XX_CHANNEL(dev);
       instance = CD18XX_INSTANCE(dev);

       /* ensure instance is valid */
       if (instance >= clcd_cd.cd_ndevs)
               return (ENXIO);

       /* get softc and port */
       sc = device_lookup_private(&clcd_cd, instance);
       if (sc == NULL)
               return (ENXIO);
       port = &sc->sc_ports[channel];

       tp = port->p_tty;

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

       if (!ISSET(tp->t_state, TS_ISOPEN) && tp->t_wopen == 0) {
               /*
                * 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.
                */
               cdtty_shutdown(sc, port);
       }

       return (0);
}

/*
* cdttyread:  read syscall for cdtty terminals..
*/
int
cdttyread(dev_t dev, struct uio *uio, int flag)
{
       struct cd18xx_softc *sc = device_lookup_private(&clcd_cd, CD18XX_INSTANCE(dev));
       struct cdtty_port *port = &sc->sc_ports[CD18XX_CHANNEL(dev)];
       struct tty *tp = port->p_tty;

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

/*
* cdttywrite:  write syscall for cdtty terminals..
*/
int
cdttywrite(dev_t dev, struct uio *uio, int flag)
{
       struct cd18xx_softc *sc = device_lookup_private(&clcd_cd, CD18XX_INSTANCE(dev));
       struct cdtty_port *port = &sc->sc_ports[CD18XX_CHANNEL(dev)];
       struct tty *tp = port->p_tty;

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

int
cdttypoll(dev_t dev, int events, struct lwp *l)
{
       struct cd18xx_softc *sc = device_lookup_private(&clcd_cd, CD18XX_INSTANCE(dev));
       struct cdtty_port *port = &sc->sc_ports[CD18XX_CHANNEL(dev)];
       struct tty *tp = port->p_tty;

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

/*
* cdttytty:  return a pointer to our (cdtty) tp.
*/
struct tty *
cdttytty(dev_t dev)
{
       struct cd18xx_softc *sc = device_lookup_private(&clcd_cd, CD18XX_INSTANCE(dev));
       struct cdtty_port *port = &sc->sc_ports[CD18XX_CHANNEL(dev)];

       return (port->p_tty);
}

/*
* cdttyioctl:  ioctl syscall for cdtty terminals..
*/
int
cdttyioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
{
       struct cd18xx_softc *sc = device_lookup_private(&clcd_cd, CD18XX_INSTANCE(dev));
       struct cdtty_port *port = &sc->sc_ports[CD18XX_CHANNEL(dev)];
       struct tty *tp = port->p_tty;
       int error, s;

       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);

       s = splserial();

       switch (cmd) {
       case TIOCSBRK:
               cdtty_break(sc, port, 1);
               break;

       case TIOCCBRK:
               cdtty_break(sc, port, 0);
               break;

       case TIOCSDTR:
               cdtty_modem(sc, port, 1);
               break;

       case TIOCCDTR:
               cdtty_modem(sc, port, 0);
               break;

       case TIOCGFLAGS:
               *(int *)data = port->p_swflags;
               break;

       case TIOCSFLAGS:
               error = kauth_authorize_device_tty(l->l_cred,
                   KAUTH_DEVICE_TTY_PRIVSET, tp);
               if (error)
                       return (error);
               port->p_swflags = *(int *)data;
               break;

       case TIOCMSET:
       case TIOCMBIS:
       case TIOCMBIC:
       case TIOCMGET:
       default:
               return (EPASSTHROUGH);
       }

       splx(s);
       return (0);
}

/*
* Start or restart transmission.
*/
static void
cdttystart(struct tty *tp)
{
       struct cd18xx_softc *sc = device_lookup_private(&clcd_cd, CD18XX_INSTANCE(tp->t_dev));
       struct cdtty_port *p = &sc->sc_ports[CD18XX_CHANNEL(tp->t_dev)];
       int s;

       s = spltty();
       if (ISSET(tp->t_state, TS_BUSY | TS_TIMEOUT | TS_TTSTOP))
               goto out;
       if (p->p_tx_stopped)
               goto out;

       if (!ttypull(tp))
               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)splserial();

               p->p_tba = tba;
               p->p_tbc = tbc;
       }

       SET(tp->t_state, TS_BUSY);
       p->p_tx_busy = 1;

       /* turn on tx interrupts */
       if ((p->p_srer & CD18xx_SRER_Tx) == 0) {
               cd18xx_set_car(sc, CD18XX_CHANNEL(tp->t_dev));
               SET(p->p_srer, CD18xx_SRER_Tx);
               cd18xx_write(sc, CD18xx_SRER, p->p_srer);
       }

       /*
        * Now bail; we can't actually transmit bytes until we're in a
        * transmit interrupt service routine.
        */
out:
       splx(s);
       return;
}

/*
* cdttystop:  handing ^S or other stop signals, for a cdtty
*/
void
cdttystop(struct tty *tp, int flag)
{
       struct cd18xx_softc *sc = device_lookup_private(&clcd_cd, CD18XX_INSTANCE(tp->t_dev));
       struct cdtty_port *p = &sc->sc_ports[CD18XX_CHANNEL(tp->t_dev)];
       int s;

       s = splserial();
       if (ISSET(tp->t_state, TS_BUSY)) {
               /* Stop transmitting at the next chunk. */
               p->p_tbc = 0;
               p->p_heldtbc = 0;
               if (!ISSET(tp->t_state, TS_TTSTOP))
                       SET(tp->t_state, TS_FLUSH);
       }
       splx(s);
}

/*
* load a channel's registers.
*/
void
cdtty_loadchannelregs(struct cd18xx_softc *sc, struct cdtty_port *p)
{

       cd18xx_set_car(sc, CD18XX_CHANNEL(p->p_tty->t_dev));
       cd18xx_write(sc, CD18xx_SRER, p->p_srer);
       cd18xx_write(sc, CD18xx_MSVR, p->p_msvr_active = p->p_msvr);
       cd18xx_write(sc, CD18xx_COR1, p->p_cor1);
       cd18xx_write(sc, CD18xx_COR2, p->p_cor2);
       cd18xx_write(sc, CD18xx_COR3, p->p_cor3);
       /*
        * COR2 and COR3 change commands are not required here for
        * the CL-CD1865 but we do them anyway for simplicity.
        */
       cd18xx_write(sc, CD18xx_CCR, CD18xx_CCR_CORCHG |
                                    CD18xx_CCR_CORCHG_COR1 |
                                    CD18xx_CCR_CORCHG_COR2 |
                                    CD18xx_CCR_CORCHG_COR3);
       cd18xx_write(sc, CD18xx_RBPRH, p->p_rbprh);
       cd18xx_write(sc, CD18xx_RBPRL, p->p_rbprl);
       cd18xx_write(sc, CD18xx_TBPRH, p->p_tbprh);
       cd18xx_write(sc, CD18xx_TBPRL, p->p_tbprl);
       if (cd18xx_wait_ccr(sc)) {
               DPRINTF(CDD_INFO,
                   ("%s: cdtty_loadchannelregs ccr wait timed out\n",
                   device_xname(sc->sc_dev)));
       }
       cd18xx_write(sc, CD18xx_CCR, p->p_chanctl);
}

/*
* Set tty parameters from termios.
* XXX - Should just copy the whole termios after
* making sure all the changes could be done.
*/
static int
cdttyparam(struct tty *tp, struct termios *t)
{
       struct cd18xx_softc *sc = device_lookup_private(&clcd_cd, CD18XX_INSTANCE(tp->t_dev));
       struct cdtty_port *p = &sc->sc_ports[CD18XX_CHANNEL(tp->t_dev)];
       int s;

       /* Check requested parameters. */
       if (t->c_ospeed < 0)
               return (EINVAL);
       if (t->c_ispeed && t->c_ispeed != t->c_ospeed)
               return (EINVAL);

       /*
        * For the console, always force CLOCAL and !HUPCL, so that the port
        * is always active.
        */
       if (ISSET(p->p_swflags, TIOCFLAG_SOFTCAR)) {
               SET(t->c_cflag, CLOCAL);
               CLR(t->c_cflag, HUPCL);
       }

       /*
        * If there were no changes, don't do anything.  This avoids dropping
        * input and improves performance when all we did was frob things like
        * VMIN and VTIME.
        */
       if (tp->t_ospeed == t->c_ospeed &&
           tp->t_cflag == t->c_cflag)
               return (0);

       /*
        * Block interrupts so that state will not
        * be altered until we are done setting it up.
        */
       s = splserial();

       /*
        * Copy across the size, parity and stop bit info.
        */
       switch (t->c_cflag & CSIZE) {
       case CS5:
               p->p_cor1 = CD18xx_COR1_CS5;
               break;
       case CS6:
               p->p_cor1 = CD18xx_COR1_CS6;
               break;
       case CS7:
               p->p_cor1 = CD18xx_COR1_CS7;
               break;
       default:
               p->p_cor1 = CD18xx_COR1_CS8;
               break;
       }
       if (ISSET(t->c_cflag, PARENB)) {
               SET(p->p_cor1, CD18xx_COR1_PARITY_NORMAL);
               if (ISSET(t->c_cflag, PARODD))
                       SET(p->p_cor1, CD18xx_COR1_PARITY_ODD);
       }
       if (!ISSET(t->c_iflag, INPCK))
               SET(p->p_cor1, CD18xx_COR1_IGNORE);
       if (ISSET(t->c_cflag, CSTOPB))
               SET(p->p_cor1, CD18xx_COR1_STOPBIT_2);

       /*
        * If we're not in a mode that assumes a connection is present, then
        * ignore carrier changes.
        */
       if (ISSET(t->c_cflag, CLOCAL | MDMBUF))
               p->p_msvr_dcd = 0;
       else
               p->p_msvr_dcd = CD18xx_MSVR_CD;

       /*
        * Set the flow control pins depending on the current flow control
        * mode.
        */
       if (ISSET(t->c_cflag, CRTSCTS)) {
               p->p_mcor1_dtr = CD18xx_MCOR1_DTR;
               p->p_msvr_rts = CD18xx_MSVR_RTS;
               p->p_msvr_cts = CD18xx_MSVR_CTS;
               p->p_cor2 = CD18xx_COR2_RTSAOE|CD18xx_COR2_CTSAE;
       } else if (ISSET(t->c_cflag, MDMBUF)) {
               /*
                * For DTR/DCD flow control, make sure we don't toggle DTR for
                * carrier detection.
                */
               p->p_mcor1_dtr = 0;
               p->p_msvr_rts = CD18xx_MSVR_DTR;
               p->p_msvr_cts = CD18xx_MSVR_CD;
               p->p_cor2 = 0;
       } else {
               /*
                * If no flow control, then always set RTS.  This will make
                * the other side happy if it mistakenly thinks we're doing
                * RTS/CTS flow control.
                */
               p->p_mcor1_dtr = CD18xx_MSVR_DTR;
               p->p_msvr_rts = 0;
               p->p_msvr_cts = 0;
               p->p_cor2 = 0;
       }
       p->p_msvr_mask = p->p_msvr_cts | p->p_msvr_dcd;

       /*
        * Set the FIFO threshold based on the receive speed.
        *
        *  * If it's a low speed, it's probably a mouse or some other
        *    interactive device, so set the threshold low.
        *  * If it's a high speed, trim the trigger level down to prevent
        *    overflows.
        *  * Otherwise set it a bit higher.
        */
       p->p_cor3 = (t->c_ospeed <= 1200 ? 1 : t->c_ospeed <= 38400 ? 8 : 4);

#define PORT_RATE(o, s) \
       (((((o) + (s)/2) / (s)) + CD18xx_xBRPR_TPC/2) / CD18xx_xBRPR_TPC)
       /* Compute BPS for the requested speeds */
       if (t->c_ospeed) {
               u_int32_t tbpr = PORT_RATE(sc->sc_osc, t->c_ospeed);

               if (tbpr == 0 || tbpr > 0xffff)
                       return (EINVAL);

               p->p_tbprh = tbpr >> 8;
               p->p_tbprl = tbpr & 0xff;
       }

       if (t->c_ispeed) {
               u_int32_t rbpr = PORT_RATE(sc->sc_osc, t->c_ispeed);

               if (rbpr == 0 || rbpr > 0xffff)
                       return (EINVAL);

               p->p_rbprh = rbpr >> 8;
               p->p_rbprl = rbpr & 0xff;
       }

       /* And copy to tty. */
       tp->t_ispeed = 0;
       tp->t_ospeed = t->c_ospeed;
       tp->t_cflag = t->c_cflag;

       if (!p->p_heldchange) {
               if (p->p_tx_busy) {
                       p->p_heldtbc = p->p_tbc;
                       p->p_tbc = 0;
                       p->p_heldchange = 1;
               } else
                       cdtty_loadchannelregs(sc, p);
       }

       if (!ISSET(t->c_cflag, CHWFLOW)) {
               /* Disable the high water mark. */
               p->p_r_hiwat = 0;
               p->p_r_lowat = 0;
               if (ISSET(p->p_rx_flags, RX_TTY_OVERFLOWED)) {
                       CLR(p->p_rx_flags, RX_TTY_OVERFLOWED);
                       softint_schedule(sc->sc_si);
               }
               if (ISSET(p->p_rx_flags, RX_TTY_BLOCKED|RX_IBUF_BLOCKED)) {
                       CLR(p->p_rx_flags, RX_TTY_BLOCKED|RX_IBUF_BLOCKED);
                       cdtty_hwiflow(sc, p);
               }
       } else {
               p->p_r_hiwat = cdtty_rbuf_hiwat;
               p->p_r_lowat = cdtty_rbuf_lowat;
       }

       splx(s);

       /*
        * Update the tty layer's idea of the carrier bit, in case we changed
        * CLOCAL or MDMBUF.  We don't hang up here; we only do that by
        * explicit request.
        */
       (void) (*tp->t_linesw->l_modem)(tp, ISSET(p->p_msvr, CD18xx_MSVR_CD));

       if (!ISSET(t->c_cflag, CHWFLOW)) {
               if (p->p_tx_stopped) {
                       p->p_tx_stopped = 0;
                       cdttystart(tp);
               }
       }

       return (0);
}

static void
cdtty_break(struct cd18xx_softc *sc, struct cdtty_port *p, int onoff)
{

       /* tell tx intr handler we need a break */
       p->p_needbreak = !!onoff;

       /* turn on tx interrupts if break has changed */
       if (p->p_needbreak != p->p_break)
               SET(p->p_srer, CD18xx_SRER_Tx);

       if (!p->p_heldchange) {
               if (p->p_tx_busy) {
                       p->p_heldtbc = p->p_tbc;
                       p->p_tbc = 0;
                       p->p_heldchange = 1;
               } else
                       cdtty_loadchannelregs(sc, p);
       }
}

/*
* Raise or lower modem control (DTR/RTS) signals.  If a character is
* in transmission, the change is deferred.
*/
static void
cdtty_modem(struct cd18xx_softc *sc, struct cdtty_port *p, int onoff)
{

       if (p->p_mcor1_dtr == 0)
               return;

       if (onoff)
               CLR(p->p_mcor1, p->p_mcor1_dtr);
       else
               SET(p->p_mcor1, p->p_mcor1_dtr);

       if (!p->p_heldchange) {
               if (p->p_tx_busy) {
                       p->p_heldtbc = p->p_tbc;
                       p->p_tbc = 0;
                       p->p_heldchange = 1;
               } else
                       cdtty_loadchannelregs(sc, p);
       }
}

/*
* 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
cdttyhwiflow(struct tty *tp, int block)
{
       struct cd18xx_softc *sc = device_lookup_private(&clcd_cd, CD18XX_INSTANCE(tp->t_dev));
       struct cdtty_port *p = &sc->sc_ports[CD18XX_CHANNEL(tp->t_dev)];
       int s;

       if (p->p_msvr_rts == 0)
               return (0);

       s = splserial();
       if (block) {
               if (!ISSET(p->p_rx_flags, RX_TTY_BLOCKED)) {
                       SET(p->p_rx_flags, RX_TTY_BLOCKED);
                       cdtty_hwiflow(sc, p);
               }
       } else {
               if (ISSET(p->p_rx_flags, RX_TTY_OVERFLOWED)) {
                       CLR(p->p_rx_flags, RX_TTY_OVERFLOWED);
                       softint_schedule(sc->sc_si);
               }
               if (ISSET(p->p_rx_flags, RX_TTY_BLOCKED)) {
                       CLR(p->p_rx_flags, RX_TTY_BLOCKED);
                       cdtty_hwiflow(sc, p);
               }
       }
       splx(s);
       return (1);
}

/*
* Internal version of cdttyhwiflow, called at cdtty's priority.
*/
static void
cdtty_hwiflow(struct cd18xx_softc *sc, struct cdtty_port *p)
{

       if (p->p_msvr_rts == 0)
               return;

       if (ISSET(p->p_rx_flags, RX_ANY_BLOCK)) {
               CLR(p->p_msvr, p->p_msvr_rts);
               CLR(p->p_msvr_active, p->p_msvr_rts);
       } else {
               SET(p->p_msvr, p->p_msvr_rts);
               SET(p->p_msvr_active, p->p_msvr_rts);
       }
       cd18xx_set_car(sc, CD18XX_CHANNEL(p->p_tty->t_dev));
       cd18xx_write(sc, CD18xx_MSVR, p->p_msvr_active);
}

/*
* indiviual interrupt routines.
*/

/*
* this is the number of interrupts allowed, total.  set it to 0
* to allow unlimited interrupts
*/
#define INTR_MAX_ALLOWED        0

#if INTR_MAX_ALLOWED == 0
#define GOTINTR(sc, p)  /* nothing */
#else
int intrcount;
#define GOTINTR(sc, p)  \
do { \
       if (intrcount++ == INTR_MAX_ALLOWED) { \
               CLR(p->p_srer, CD18xx_SRER_Tx); \
               cd18xx_write(sc, CD18xx_SRER, p->p_srer); \
       } \
       DPRINTF(CDD_INTR, (", intrcount %d srer %x", intrcount, p->p_srer)); \
} while (0)
#endif

/* receiver interrupt */
static inline void
cd18xx_rint(struct cd18xx_softc *sc, int *ns)
{
       struct cdtty_port *p;
       u_int channel, count;
       u_char *put, *end;
       u_int cc;

       /* work out the channel and softc */
       channel = cd18xx_get_gscr1_channel(sc);
       p = &sc->sc_ports[channel];
       DPRINTF(CDD_INTR, ("%s: rint: channel %d", device_xname(sc->sc_dev), channel));
       GOTINTR(sc, p);

       end = p->p_ebuf;
       put = p->p_rbput;
       cc = p->p_rbavail;

       /* read as many bytes as necessary */
       count = cd18xx_read(sc, CD18xx_RDCR);
       DPRINTF(CDD_INTR, (", %d bytes available: ", count));

       while (cc > 0 && count > 0) {
               u_char rcsr = cd18xx_read(sc, CD18xx_RCSR);

               put[0] = cd18xx_read(sc, CD18xx_RDR);
               put[1] = rcsr;

               if (rcsr)
                       *ns = 1;

               put += 2;
               if (put >= end)
                       put = p->p_rbuf;

               DPRINTF(CDD_INTR, ("."));
               cc--;
               count--;
       }

       DPRINTF(CDD_INTR, (" finished reading"));

       /*
        * Current string of incoming characters ended because
        * no more data was available or we ran out of space.
        * If we're out of space, turn off receive interrupts.
        */
       p->p_rbput = put;
       p->p_rbavail = cc;
       if (!ISSET(p->p_rx_flags, RX_TTY_OVERFLOWED)) {
               p->p_rx_ready = 1;
       }

       /*
        * If we're out of space, disable receive interrupts
        * until the queue has drained a bit.
        */
       if (!cc) {
               SET(p->p_rx_flags, RX_IBUF_OVERFLOWED);
               CLR(p->p_srer, CD18xx_SRER_Rx |
                              CD18xx_SRER_RxSC |
                              CD18xx_SRER_CD);
               cd18xx_write(sc, CD18xx_SRER, p->p_srer);
       }

       /* finish the interrupt transaction with the IC */
       cd18xx_write(sc, CD18xx_EOSRR, 0);
       DPRINTF(CDD_INTR, (", done\n"));
}

/*
* transmitter interrupt
*
* note this relys on the fact that we allow the transmitter FIFO to
* drain completely
*/
static inline void
cd18xx_tint(struct cd18xx_softc *sc, int *ns)
{
       struct cdtty_port *p;
       u_int channel;

       /* work out the channel and softc */
       channel = cd18xx_get_gscr1_channel(sc);
       p = &sc->sc_ports[channel];
       DPRINTF(CDD_INTR, ("%s: tint: channel %d", device_xname(sc->sc_dev),
           channel));
       GOTINTR(sc, p);

       /* if the current break condition is wrong, fix it */
       if (p->p_break != p->p_needbreak) {
               u_char buf[2];

               DPRINTF(CDD_INTR, (", changing break to %d", p->p_needbreak));

               /* turn on ETC processing */
               cd18xx_write(sc, CD18xx_COR2, p->p_cor2 | CD18xx_COR2_ETC);

               buf[0] = CD18xx_TDR_ETC_BYTE;
               buf[1] = p->p_needbreak ? CD18xx_TDR_BREAK_BYTE :
                                           CD18xx_TDR_NOBREAK_BYTE;
               cd18xx_write_multi(sc, CD18xx_TDR, buf, 2);

               p->p_break = p->p_needbreak;

               /* turn off ETC processing */
               cd18xx_write(sc, CD18xx_COR2, p->p_cor2);
       }

       /*
        * If we've delayed a parameter change, do it now, and restart
        * output.
        */
       if (p->p_heldchange) {
               cdtty_loadchannelregs(sc, p);
               p->p_heldchange = 0;
               p->p_tbc = p->p_heldtbc;
               p->p_heldtbc = 0;
       }

       /* Output the next chunk of the contiguous buffer, if any. */
       if (p->p_tbc > 0) {
               int n;

               n = p->p_tbc;
               if (n > 8) /* write up to 8 entries */
                       n = 8;
               DPRINTF(CDD_INTR, (", writing %d bytes to TDR", n));
               cd18xx_write_multi(sc, CD18xx_TDR, p->p_tba, n);
               p->p_tbc -= n;
               p->p_tba += n;
       }

       /* Disable transmit completion interrupts if we ran out of bytes. */
       if (p->p_tbc == 0) {
               /* Note that Tx interrupts should already be enabled */
               if (ISSET(p->p_srer, CD18xx_SRER_Tx)) {
                       DPRINTF(CDD_INTR, (", disabling tx interrupts"));
                       CLR(p->p_srer, CD18xx_SRER_Tx);
                       cd18xx_write(sc, CD18xx_SRER, p->p_srer);
               }
               if (p->p_tx_busy) {
                       p->p_tx_busy = 0;
                       p->p_tx_done = 1;
               }
       }
       *ns = 1;

       /* finish the interrupt transaction with the IC */
       cd18xx_write(sc, CD18xx_EOSRR, 0);
       DPRINTF(CDD_INTR, (", done\n"));
}

/* modem signal change interrupt */
static inline void
cd18xx_mint(struct cd18xx_softc *sc, int *ns)
{
       struct cdtty_port *p;
       u_int channel;
       u_char msvr, delta;

       /* work out the channel and softc */
       channel = cd18xx_get_gscr1_channel(sc);
       p = &sc->sc_ports[channel];
       DPRINTF(CDD_INTR, ("%s: mint: channel %d", device_xname(sc->sc_dev), channel));
       GOTINTR(sc, p);

       /*
        * We ignore the MCR register, and handle detecting deltas
        * via software, like many other serial drivers.
        */
       msvr = cd18xx_read(sc, CD18xx_MSVR);
       delta = msvr ^ p->p_msvr;
       DPRINTF(CDD_INTR, (", msvr %d", msvr));

       /*
        * Process normal status changes
        */
       if (ISSET(delta, p->p_msvr_mask)) {
               SET(p->p_msvr_delta, delta);

               DPRINTF(CDD_INTR, (", status changed delta %d", delta));
               /*
                * Stop output immediately if we lose the output
                * flow control signal or carrier detect.
                */
               if (ISSET(~msvr, p->p_msvr_mask)) {
                       p->p_tbc = 0;
                       p->p_heldtbc = 0;
                       /* Stop modem interrupt processing */
               }
               p->p_st_check = 1;
               *ns = 1;
       }

       /* reset the modem signal register */
       cd18xx_write(sc, CD18xx_MCR, 0);

       /* finish the interrupt transaction with the IC */
       cd18xx_write(sc, CD18xx_EOSRR, 0);
       DPRINTF(CDD_INTR, (", done\n"));
}

/*
* hardware interrupt routine.  call the relevant interrupt routines until
* no interrupts are pending.
*
* note:  we do receive interrupts before all others (as we'd rather lose
* a chance to transmit, than lose a character).  and we do transmit
* interrupts before modem interrupts.
*
* we have to traverse all of the cd18xx's attached, unfortunately.
*/
int
cd18xx_hardintr(void *v)
{
       int i, rv = 0;
       u_char ack;

       DPRINTF(CDD_INTR, ("cd18xx_hardintr (ndevs %d):\n", clcd_cd.cd_ndevs));
       for (i = 0; i < clcd_cd.cd_ndevs; i++)
       {
               struct cd18xx_softc *sc = device_lookup_private(&clcd_cd, i);
               int status, ns = 0;
               int count = 1;  /* process only 1 interrupts at a time for now */

               if (sc == NULL)
                       continue;

               DPRINTF(CDD_INTR, ("%s:", device_xname(sc->sc_dev)));
               while (count-- &&
                   (status = (cd18xx_read(sc, CD18xx_SRSR) &
                    CD18xx_SRSR_PENDING))) {
                       rv = 1;

                       DPRINTF(CDD_INTR, (" status %x:", status));
                       if (ISSET(status, CD18xx_SRSR_RxPEND)) {
                               ack = (*sc->sc_ackfunc)(sc->sc_ackfunc_arg,
                                   CD18xx_INTRACK_RxINT);
                               DPRINTF(CDD_INTR, (" rx: ack1 %x\n", ack));
                               cd18xx_rint(sc, &ns);
                       }
                       if (ISSET(status, CD18xx_SRSR_TxPEND)) {
                               ack = (*sc->sc_ackfunc)(sc->sc_ackfunc_arg,
                                   CD18xx_INTRACK_TxINT);
                               DPRINTF(CDD_INTR, (" tx: ack1 %x\n", ack));
                               cd18xx_tint(sc, &ns);

                       }
                       if (ISSET(status, CD18xx_SRSR_MxPEND)) {
                               ack = (*sc->sc_ackfunc)(sc->sc_ackfunc_arg,
                                   CD18xx_INTRACK_MxINT);
                               DPRINTF(CDD_INTR, (" mx: ack1 %x\n", ack));
                               cd18xx_mint(sc, &ns);
                       }
               }
               if (ns)
                       softint_schedule(sc->sc_si);
       }

       return (rv);
}

/*
* software interrupt
*/

void
cdtty_rxsoft(struct cd18xx_softc *sc, struct cdtty_port *p, struct tty *tp)
{
       u_char *get, *end;
       u_int cc, scc;
       u_char rcsr;
       int code;
       int s;

       end = p->p_ebuf;
       get = p->p_rbget;
       scc = cc = cdtty_rbuf_size - p->p_rbavail;

       if (cc == cdtty_rbuf_size) {
               p->p_floods++;
#if 0
               if (p->p_errors++ == 0)
                       callout_reset(&p->p_diag_callout, 60 * hz,
                           cdttydiag, p);
#endif
       }

       while (cc) {
               code = get[0];
               rcsr = get[1];
               if (ISSET(rcsr, CD18xx_RCSR_OVERRUNERR | CD18xx_RCSR_BREAK |
                               CD18xx_RCSR_FRAMERR | CD18xx_RCSR_PARITYERR)) {
                       if (ISSET(rcsr, CD18xx_RCSR_OVERRUNERR)) {
                               p->p_overflows++;
#if 0
                               if (p->p_errors++ == 0)
                                       callout_reset(&p->p_diag_callout,
                                           60 * hz, cdttydiag, p);
#endif
                       }
                       if (ISSET(rcsr, CD18xx_RCSR_BREAK|CD18xx_RCSR_FRAMERR))
                               SET(code, TTY_FE);
                       if (ISSET(rcsr, CD18xx_RCSR_PARITYERR))
                               SET(code, TTY_PE);
               }
               if ((*tp->t_linesw->l_rint)(code, tp) == -1) {
                       /*
                        * The line discipline's buffer is out of space.
                        */
                       if (!ISSET(p->p_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 -= cdtty_rbuf_size << 1;
                               cc = 0;
                       } else {
                               /*
                                * Don't schedule any more receive processing
                                * until the line discipline tells us there's
                                * space available (through cdttyhwiflow()).
                                * Leave the rest of the data in the input
                                * buffer.
                                */
                               SET(p->p_rx_flags, RX_TTY_OVERFLOWED);
                       }
                       break;
               }
               get += 2;
               if (get >= end)
                       get = p->p_rbuf;
               cc--;
       }

       if (cc != scc) {
               p->p_rbget = get;
               s = splserial();

               cc = p->p_rbavail += scc - cc;
               /* Buffers should be ok again, release possible block. */
               if (cc >= p->p_r_lowat) {
                       if (ISSET(p->p_rx_flags, RX_IBUF_OVERFLOWED)) {
                               CLR(p->p_rx_flags, RX_IBUF_OVERFLOWED);
                               cd18xx_set_car(sc, CD18XX_CHANNEL(tp->t_dev));
                               SET(p->p_srer, CD18xx_SRER_Rx |
                                              CD18xx_SRER_RxSC |
                                              CD18xx_SRER_CD);
                               cd18xx_write(sc, CD18xx_SRER, p->p_srer);
                       }
                       if (ISSET(p->p_rx_flags, RX_IBUF_BLOCKED)) {
                               CLR(p->p_rx_flags, RX_IBUF_BLOCKED);
                               cdtty_hwiflow(sc, p);
                       }
               }
               splx(s);
       }
}

void
cdtty_txsoft(struct cd18xx_softc *sc, struct cdtty_port *p, 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)(p->p_tba - tp->t_outq.c_cf));
       (*tp->t_linesw->l_start)(tp);
}

void
cdtty_stsoft(struct cd18xx_softc *sc, struct cdtty_port *p, struct tty *tp)
{
       u_char msvr, delta;
       int s;

       s = splserial();
       msvr = p->p_msvr;
       delta = p->p_msvr_delta;
       p->p_msvr_delta = 0;
       splx(s);

       if (ISSET(delta, p->p_msvr_dcd)) {
               /*
                * Inform the tty layer that carrier detect changed.
                */
               (void) (*tp->t_linesw->l_modem)(tp, ISSET(msvr, CD18xx_MSVR_CD));
       }

       if (ISSET(delta, p->p_msvr_cts)) {
               /* Block or unblock output according to flow control. */
               if (ISSET(msvr, p->p_msvr_cts)) {
                       p->p_tx_stopped = 0;
                       (*tp->t_linesw->l_start)(tp);
               } else {
                       p->p_tx_stopped = 1;
               }
       }
}

void
cd18xx_softintr(void *v)
{
       struct cd18xx_softc *sc = v;
       struct cdtty_port *p;
       struct tty *tp;
       int i;

       for (i = 0; i < 8; i++) {
               p = &sc->sc_ports[i];

               tp = p->p_tty;
               if (tp == NULL)
                       continue;
               if (!ISSET(tp->t_state, TS_ISOPEN) && tp->t_wopen == 0)
                       continue;

               if (p->p_rx_ready) {
                       p->p_rx_ready = 0;
                       cdtty_rxsoft(sc, p, tp);
               }

               if (p->p_st_check) {
                       p->p_st_check = 0;
                       cdtty_stsoft(sc, p, tp);
               }

               if (p->p_tx_done) {
                       p->p_tx_done = 0;
                       cdtty_txsoft(sc, p, tp);
               }
       }
}