/*      $NetBSD: sscom.c,v 1.50 2022/10/26 23:38:06 riastradh Exp $ */

/*
 * Copyright (c) 2002, 2003 Fujitsu Component Limited
 * Copyright (c) 2002, 2003 Genetec Corporation
 * 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 Fujitsu Component Limited nor the name of
 *    Genetec corporation may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY FUJITSU COMPONENT LIMITED AND GENETEC
 * CORPORATION ``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 FUJITSU COMPONENT LIMITED OR GENETEC
 * CORPORATION 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
 */

/*
 * Support integrated UARTs of Samsung S3C2800/2400X/2410X
 * Derived from sys/dev/ic/com.c
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: sscom.c,v 1.50 2022/10/26 23:38:06 riastradh Exp $");

#include "opt_sscom.h"
#include "opt_kgdb.h"
#include "opt_multiprocessor.h"
#include "opt_lockdebug.h"

#ifdef RND_COM
#include <sys/rndsource.h>
#endif

/*
 * Override cnmagic(9) macro before including <sys/systm.h>.
 * We need to know if cn_check_magic triggered debugger, so set a flag.
 * Callers of cn_check_magic must declare int cn_trapped = 0;
 * XXX: this is *ugly*!
 */
#define cn_trap()                               \
        do {                                    \
                console_debugger();             \
                cn_trapped = 1;                 \
        } while (/* CONSTCOND */ 0)

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/ioctl.h>
#include <sys/select.h>
#include <sys/tty.h>
#include <sys/proc.h>
#include <sys/conf.h>
#include <sys/file.h>
#include <sys/uio.h>
#include <sys/kernel.h>
#include <sys/syslog.h>
#include <sys/types.h>
#include <sys/device.h>
#include <sys/kmem.h>
#include <sys/timepps.h>
#include <sys/vnode.h>
#include <sys/kauth.h>
#include <sys/intr.h>
#include <sys/bus.h>
#include <sys/mutex.h>

#include <ddb/db_active.h>

#include <arm/s3c2xx0/s3c2xx0reg.h>
#include <arm/s3c2xx0/sscom_var.h>
#include <dev/cons.h>

dev_type_open(sscomopen);
dev_type_close(sscomclose);
dev_type_read(sscomread);
dev_type_write(sscomwrite);
dev_type_ioctl(sscomioctl);
dev_type_stop(sscomstop);
dev_type_tty(sscomtty);
dev_type_poll(sscompoll);

int     sscomcngetc     (dev_t);
void    sscomcnputc     (dev_t, int);
void    sscomcnpollc    (dev_t, int);

#define integrate       static inline
void    sscomsoft       (void *);

integrate void sscom_rxsoft     (struct sscom_softc *, struct tty *);
integrate void sscom_txsoft     (struct sscom_softc *, struct tty *);
integrate void sscom_stsoft     (struct sscom_softc *, struct tty *);
integrate void sscom_schedrx    (struct sscom_softc *);
static void     sscom_modem(struct sscom_softc *, int);
static void     sscom_break(struct sscom_softc *, int);
static void     sscom_iflush(struct sscom_softc *);
static void     sscom_hwiflow(struct sscom_softc *);
static void     sscom_loadchannelregs(struct sscom_softc *);
static void     tiocm_to_sscom(struct sscom_softc *, u_long, int);
static int      sscom_to_tiocm(struct sscom_softc *);
static void     tiocm_to_sscom(struct sscom_softc *, u_long, int);
static int      sscom_to_tiocm(struct sscom_softc *);
static void     sscom_iflush(struct sscom_softc *);

static int      sscomhwiflow(struct tty *tp, int block);
#if defined(KGDB) || defined(SSCOM0CONSOLE) || defined(SSCOM1CONSOLE)
static int      sscom_init(bus_space_tag_t, const struct sscom_uart_info *,
                    int, int, tcflag_t, bus_space_handle_t *);
#endif

extern struct cfdriver sscom_cd;

const struct cdevsw sscom_cdevsw = {
        .d_open = sscomopen,
        .d_close = sscomclose,
        .d_read = sscomread,
        .d_write = sscomwrite,
        .d_ioctl = sscomioctl,
        .d_stop = sscomstop,
        .d_tty = sscomtty,
        .d_poll = sscompoll,
        .d_mmap = nommap,
        .d_kqfilter = ttykqfilter,
        .d_discard = nodiscard,
        .d_flag = D_TTY
};

/*
 * Make this an option variable one can patch.
 * But be warned:  this must be a power of 2!
 */
u_int sscom_rbuf_size = SSCOM_RING_SIZE;

/* Stop input when 3/4 of the ring is full; restart when only 1/4 is full. */
u_int sscom_rbuf_hiwat = (SSCOM_RING_SIZE * 1) / 4;
u_int sscom_rbuf_lowat = (SSCOM_RING_SIZE * 3) / 4;

static int      sscomconsunit = -1;
static bus_space_tag_t sscomconstag;
static bus_space_handle_t sscomconsioh;
static int      sscomconsattached;
static int      sscomconsrate;
static tcflag_t sscomconscflag;
static struct cnm_state sscom_cnm_state;

#ifdef KGDB
#include <sys/kgdb.h>

static int sscom_kgdb_unit = -1;
static bus_space_tag_t sscom_kgdb_iot;
static bus_space_handle_t sscom_kgdb_ioh;
static int sscom_kgdb_attached;

int     sscom_kgdb_getc (void *);
void    sscom_kgdb_putc (void *, int);
#endif /* KGDB */

#define SSCOMUNIT_MASK          0x7f
#define SSCOMDIALOUT_MASK       0x80

#define SSCOMUNIT(x)    (minor(x) & SSCOMUNIT_MASK)
#define SSCOMDIALOUT(x) (minor(x) & SSCOMDIALOUT_MASK)

#if 0
#define SSCOM_ISALIVE(sc)       ((sc)->enabled != 0 && \
                                 device_is_active(&(sc)->sc_dev))
#else
#define SSCOM_ISALIVE(sc)       device_is_active((sc)->sc_dev)
#endif

#define BR      BUS_SPACE_BARRIER_READ
#define BW      BUS_SPACE_BARRIER_WRITE
#define SSCOM_BARRIER(t, h, f) /* no-op */

#if (defined(MULTIPROCESSOR) || defined(LOCKDEBUG)) && defined(SSCOM_MPLOCK)

#define SSCOM_LOCK(sc) mutex_enter((sc)->sc_lock)
#define SSCOM_UNLOCK(sc) mutex_exit((sc)->sc_lock)

#else

#define SSCOM_LOCK(sc)
#define SSCOM_UNLOCK(sc)

#endif

#ifndef SSCOM_TOLERANCE
#define SSCOM_TOLERANCE 30      /* XXX: baud rate tolerance, in 0.1% units */
#endif

/* value for UCON */
#define UCON_RXINT_MASK   \
        (UCON_RXMODE_MASK|UCON_ERRINT|UCON_TOINT|UCON_RXINT_TYPE)
#define UCON_RXINT_ENABLE \
        (UCON_RXMODE_INT|UCON_ERRINT|UCON_TOINT|UCON_RXINT_TYPE_LEVEL)
#define UCON_TXINT_MASK   (UCON_TXMODE_MASK|UCON_TXINT_TYPE)
#define UCON_TXINT_ENABLE (UCON_TXMODE_INT|UCON_TXINT_TYPE_LEVEL)

/* we don't want tx interrupt on debug port, but it is needed to
   have transmitter active */
#define UCON_DEBUGPORT    (UCON_RXINT_ENABLE|UCON_TXINT_ENABLE)


static inline void
__sscom_output_chunk(struct sscom_softc *sc, int ufstat)
{
        int n, space;
        bus_space_tag_t iot = sc->sc_iot;
        bus_space_handle_t ioh = sc->sc_ioh;

        n = sc->sc_tbc;
        space = 16 - ((ufstat & UFSTAT_TXCOUNT) >> UFSTAT_TXCOUNT_SHIFT);

        if (n > space)
                n = space;

        if (n > 0) {
                bus_space_write_multi_1(iot, ioh, SSCOM_UTXH, sc->sc_tba, n);
                sc->sc_tbc -= n;
                sc->sc_tba += n;
        }
}

static void
sscom_output_chunk(struct sscom_softc *sc)
{
        int ufstat = bus_space_read_2(sc->sc_iot, sc->sc_ioh, SSCOM_UFSTAT);

        if (!(ufstat & UFSTAT_TXFULL))
                __sscom_output_chunk(sc, ufstat);
}

int
sscomspeed(long speed, long frequency)
{
#define divrnd(n, q)    (((n)*2/(q)+1)/2)       /* divide and round off */

        int x, err;

        if (speed <= 0)
                return -1;
        x = divrnd(frequency / 16, speed);
        if (x <= 0)
                return -1;
        err = divrnd(((quad_t)frequency) * 1000 / 16, speed * x) - 1000;
        if (err < 0)
                err = -err;
        if (err > SSCOM_TOLERANCE)
                return -1;
        return x-1;

#undef  divrnd
}

void sscomstatus (struct sscom_softc *, const char *);

#ifdef SSCOM_DEBUG
int     sscom_debug = 0;

void
sscomstatus(struct sscom_softc *sc, const char *str)
{
        struct tty *tp = sc->sc_tty;
        int umstat = bus_space_read_1(sc->sc_iot, sc->sc_iot, SSCOM_UMSTAT);
        int umcon = bus_space_read_1(sc->sc_iot, sc->sc_iot, SSCOM_UMCON);

        printf("%s: %s %sclocal  %sdcd %sts_carr_on %sdtr %stx_stopped\n",
            device_xname(sc->sc_dev), str,
            ISSET(tp->t_cflag, CLOCAL) ? "+" : "-",
            "+",                        /* DCD */
            ISSET(tp->t_state, TS_CARR_ON) ? "+" : "-",
            "+",                        /* DTR */
            sc->sc_tx_stopped ? "+" : "-");

        printf("%s: %s %scrtscts %scts %sts_ttstop  %srts %xrx_flags\n",
            device_xname(sc->sc_dev), str,
            ISSET(tp->t_cflag, CRTSCTS) ? "+" : "-",
            ISSET(umstat, UMSTAT_CTS) ? "+" : "-",
            ISSET(tp->t_state, TS_TTSTOP) ? "+" : "-",
            ISSET(umcon, UMCON_RTS) ? "+" : "-",
            sc->sc_rx_flags);
}
#else
#define sscom_debug  0
#endif

static void
sscom_enable_debugport(struct sscom_softc *sc)
{
        int s;

        /* Turn on line break interrupt, set carrier. */
        s = splserial();
        SSCOM_LOCK(sc);
        sc->sc_ucon = UCON_DEBUGPORT;
        bus_space_write_2(sc->sc_iot, sc->sc_ioh, SSCOM_UCON, sc->sc_ucon);
        sc->sc_umcon = UMCON_RTS|UMCON_DTR;
        sc->sc_set_modem_control(sc);
        sscom_enable_rxint(sc);
        sscom_disable_txint(sc);
        SSCOM_UNLOCK(sc);
        splx(s);
}

static void
sscom_set_modem_control(struct sscom_softc *sc)
{
        /* flob RTS */
        bus_space_write_1(sc->sc_iot, sc->sc_ioh,
            SSCOM_UMCON, sc->sc_umcon & UMCON_HW_MASK);
        /* ignore DTR */
}

static int
sscom_read_modem_status(struct sscom_softc *sc)
{
        int msts;

        msts = bus_space_read_1(sc->sc_iot, sc->sc_ioh, SSCOM_UMSTAT);

        /* DCD and DSR are always on */
        return (msts & UMSTAT_CTS) | MSTS_DCD | MSTS_DSR;
}

void
sscom_attach_subr(struct sscom_softc *sc)
{
        int unit = sc->sc_unit;
        bus_space_tag_t iot = sc->sc_iot;
        bus_space_handle_t ioh = sc->sc_ioh;
        struct tty *tp;

        callout_init(&sc->sc_diag_callout, 0);
#if (defined(MULTIPROCESSOR) || defined(LOCKDEBUG)) && defined(SSCOM_MPLOCK)
        sc->sc_lock = mutex_obj_alloc(MUTEX_DEFAULT, IPL_SERIAL);
#endif

        sc->sc_ucon = UCON_RXINT_ENABLE|UCON_TXINT_ENABLE;

        /*
         * set default for modem control hook
         */
        if (sc->sc_set_modem_control == NULL)
                sc->sc_set_modem_control = sscom_set_modem_control;
        if (sc->sc_read_modem_status == NULL)
                sc->sc_read_modem_status = sscom_read_modem_status;

        /* Disable interrupts before configuring the device. */
        KASSERT(sc->sc_change_txrx_interrupts != NULL);
        sscom_disable_txrxint(sc);

#ifdef KGDB
        /*
         * Allow kgdb to "take over" this port.  If this is
         * the kgdb device, it has exclusive use.
         */
        if (unit == sscom_kgdb_unit) {
                SET(sc->sc_hwflags, SSCOM_HW_KGDB);
                sc->sc_ucon = UCON_DEBUGPORT;
        }
#endif

        if (unit == sscomconsunit) {
                int timo, stat;

                sscomconsattached = 1;
                sscomconstag = iot;
                sscomconsioh = ioh;

                /* wait for this transmission to complete */
                timo = 1500000;
                do {
                        stat = bus_space_read_1(iot, ioh, SSCOM_UTRSTAT);
                } while ((stat & UTRSTAT_TXEMPTY) == 0 && --timo > 0);

                /* Make sure the console is always "hardwired". */
                SET(sc->sc_hwflags, SSCOM_HW_CONSOLE);
                SET(sc->sc_swflags, TIOCFLAG_SOFTCAR);

                sc->sc_ucon = UCON_DEBUGPORT;
        }

        bus_space_write_1(iot, ioh, SSCOM_UFCON,
#ifdef SSCOM_S3C2440
            UFCON_TXTRIGGER_16|UFCON_RXTRIGGER_16|UFCON_FIFO_ENABLE|
#else
            UFCON_TXTRIGGER_8|UFCON_RXTRIGGER_8|UFCON_FIFO_ENABLE|
#endif
            UFCON_TXFIFO_RESET|UFCON_RXFIFO_RESET);

        bus_space_write_1(iot, ioh, SSCOM_UCON, sc->sc_ucon);

#ifdef KGDB
        if (ISSET(sc->sc_hwflags, SSCOM_HW_KGDB)) {
                sscom_kgdb_attached = 1;
                printf("%s: kgdb\n", device_xname(sc->sc_dev));
                sscom_enable_debugport(sc);
                return;
        }
#endif

        tp = tty_alloc();
        tp->t_oproc = sscomstart;
        tp->t_param = sscomparam;
        tp->t_hwiflow = sscomhwiflow;

        sc->sc_tty = tp;
        sc->sc_rbuf = kmem_alloc(sscom_rbuf_size << 1, KM_SLEEP);
        sc->sc_rbput = sc->sc_rbget = sc->sc_rbuf;
        sc->sc_rbavail = sscom_rbuf_size;
        sc->sc_ebuf = sc->sc_rbuf + (sscom_rbuf_size << 1);

        tty_attach(tp);

        if (ISSET(sc->sc_hwflags, SSCOM_HW_CONSOLE)) {
                int maj;

                /* locate the major number */
                maj = cdevsw_lookup_major(&sscom_cdevsw);

                cn_tab->cn_dev = makedev(maj, device_unit(sc->sc_dev));

                printf("%s: console (major=%d)\n", device_xname(sc->sc_dev), maj);
        }


        sc->sc_si = softint_establish(SOFTINT_SERIAL, sscomsoft, sc);

#ifdef RND_COM
        rnd_attach_source(&sc->rnd_source, device_xname(sc->sc_dev),
                          RND_TYPE_TTY, RND_FLAG_COLLECT_TIME|
                                        RND_FLAG_ESTIMATE_TIME);
#endif

        /* if there are no enable/disable functions, assume the device
           is always enabled */

        if (ISSET(sc->sc_hwflags, SSCOM_HW_CONSOLE))
                sscom_enable_debugport(sc);
        else 
                sscom_disable_txrxint(sc);

        SET(sc->sc_hwflags, SSCOM_HW_DEV_OK);
}

int
sscom_detach(device_t self, int flags)
{
        struct sscom_softc *sc = device_private(self);

        if (sc->sc_hwflags & (SSCOM_HW_CONSOLE|SSCOM_HW_KGDB))
                return EBUSY;

        return 0;
}

int
sscom_activate(device_t self, enum devact act)
{
#ifdef notyet
        struct sscom_softc *sc = device_private(self);
#endif

        switch (act) {
        case DVACT_DEACTIVATE:
#ifdef notyet
                sc->enabled = 0;
#endif
                return 0;
        default:
                return EOPNOTSUPP;
        }
}

void
sscom_shutdown(struct sscom_softc *sc)
{
#ifdef notyet
        struct tty *tp = sc->sc_tty;
        int s;

        s = splserial();
        SSCOM_LOCK(sc); 

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

        /* Clear any break condition set with TIOCSBRK. */
        sscom_break(sc, 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)) {
                sscom_modem(sc, 0);
                SSCOM_UNLOCK(sc);
                splx(s);
                /* XXX tsleep will only timeout */
                (void) tsleep(sc, TTIPRI, ttclos, hz);
                s = splserial();
                SSCOM_LOCK(sc); 
        }

        if (ISSET(sc->sc_hwflags, SSCOM_HW_CONSOLE))
                /* interrupt on break */
                sc->sc_ucon = UCON_DEBUGPORT;
        else
                sc->sc_ucon = 0;
        bus_space_write_2(sc->sc_iot, sc->sc_ioh, SSCOM_UCON, sc->sc_ucon);

#ifdef DIAGNOSTIC
        if (!sc->enabled)
                panic("sscom_shutdown: not enabled?");
#endif
        sc->enabled = 0;
        SSCOM_UNLOCK(sc);
        splx(s);
#endif
}

int
sscomopen(dev_t dev, int flag, int mode, struct lwp *l)
{
        struct sscom_softc *sc;
        struct tty *tp;
        int s, s2;
        int error;

        sc = device_lookup_private(&sscom_cd, SSCOMUNIT(dev));
        if (sc == NULL || !ISSET(sc->sc_hwflags, SSCOM_HW_DEV_OK) ||
                sc->sc_rbuf == NULL)
                return ENXIO;

        if (!device_is_active(sc->sc_dev))
                return ENXIO;

#ifdef KGDB
        /*
         * If this is the kgdb port, no other use is permitted.
         */
        if (ISSET(sc->sc_hwflags, SSCOM_HW_KGDB))
                return EBUSY;
#endif

        tp = sc->sc_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;

                tp->t_dev = dev;

                s2 = splserial();
                SSCOM_LOCK(sc);

                /* Turn on interrupts. */
                sscom_enable_txrxint(sc);

                /* Fetch the current modem control status, needed later. */
                sc->sc_msts = sc->sc_read_modem_status(sc);

#if 0
                /* Clear PPS capture state on first open. */
                sc->sc_ppsmask = 0;
                sc->ppsparam.mode = 0;
#endif

                SSCOM_UNLOCK(sc);
                splx(s2);

                /*
                 * Initialize the termios status to the defaults.  Add in the
                 * sticky bits from TIOCSFLAGS.
                 */
                t.c_ispeed = 0;
                if (ISSET(sc->sc_hwflags, SSCOM_HW_CONSOLE)) {
                        t.c_ospeed = sscomconsrate;
                        t.c_cflag = sscomconscflag;
                } else {
                        t.c_ospeed = TTYDEF_SPEED;
                        t.c_cflag = TTYDEF_CFLAG;
                }
                if (ISSET(sc->sc_swflags, TIOCFLAG_CLOCAL))
                        SET(t.c_cflag, CLOCAL);
                if (ISSET(sc->sc_swflags, TIOCFLAG_CRTSCTS))
                        SET(t.c_cflag, CRTSCTS);
                if (ISSET(sc->sc_swflags, TIOCFLAG_MDMBUF))
                        SET(t.c_cflag, MDMBUF);
                /* Make sure sscomparam() will do something. */
                tp->t_ospeed = 0;
                (void) sscomparam(tp, &t);
                tp->t_iflag = TTYDEF_IFLAG;
                tp->t_oflag = TTYDEF_OFLAG;
                tp->t_lflag = TTYDEF_LFLAG;
                ttychars(tp);
                ttsetwater(tp);

                s2 = splserial();
                SSCOM_LOCK(sc);

                /*
                 * Turn on DTR.  We must always do this, even if carrier is not
                 * present, because otherwise we'd have to use TIOCSDTR
                 * immediately after setting CLOCAL, which applications do not
                 * expect.  We always assert DTR while the device is open
                 * unless explicitly requested to deassert it.
                 */
                sscom_modem(sc, 1);

                /* Clear the input ring, and unblock. */
                sc->sc_rbput = sc->sc_rbget = sc->sc_rbuf;
                sc->sc_rbavail = sscom_rbuf_size;
                sscom_iflush(sc);
                CLR(sc->sc_rx_flags, RX_ANY_BLOCK);
                sscom_hwiflow(sc);

                if (sscom_debug)
                        sscomstatus(sc, "sscomopen  ");

                SSCOM_UNLOCK(sc);
                splx(s2);
        }
        
        splx(s);

        error = ttyopen(tp, SSCOMDIALOUT(dev), ISSET(flag, O_NONBLOCK));
        if (error)
                goto bad;

        error = (*tp->t_linesw->l_open)(dev, tp);
        if (error)
                goto bad;

        return 0;

bad:
        if (!ISSET(tp->t_state, TS_ISOPEN) && tp->t_wopen == 0) {
                /*
                 * We failed to open the device, and nobody else had it opened.
                 * Clean up the state as appropriate.
                 */
                sscom_shutdown(sc);
        }

        return error;
}
 
int
sscomclose(dev_t dev, int flag, int mode, struct lwp *l)
{
        struct sscom_softc *sc = device_lookup_private(&sscom_cd, SSCOMUNIT(dev));
        struct tty *tp = sc->sc_tty;

        /* XXX This is for cons.c. */
        if (!ISSET(tp->t_state, TS_ISOPEN))
                return 0;

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

        if (SSCOM_ISALIVE(sc) == 0)
                return 0;

        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.
                 */
                sscom_shutdown(sc);
        }

        return 0;
}
 
int
sscomread(dev_t dev, struct uio *uio, int flag)
{
        struct sscom_softc *sc = device_lookup_private(&sscom_cd, SSCOMUNIT(dev));
        struct tty *tp = sc->sc_tty;

        if (SSCOM_ISALIVE(sc) == 0)
                return EIO;
 
        return (*tp->t_linesw->l_read)(tp, uio, flag);
}
 
int
sscomwrite(dev_t dev, struct uio *uio, int flag)
{
        struct sscom_softc *sc = device_lookup_private(&sscom_cd, SSCOMUNIT(dev));
        struct tty *tp = sc->sc_tty;

        if (SSCOM_ISALIVE(sc) == 0)
                return EIO;
 
        return (*tp->t_linesw->l_write)(tp, uio, flag);
}

int
sscompoll(dev_t dev, int events, struct lwp *l)
{
        struct sscom_softc *sc = device_lookup_private(&sscom_cd, SSCOMUNIT(dev));
        struct tty *tp = sc->sc_tty;

        if (SSCOM_ISALIVE(sc) == 0)
                return EIO;
 
        return (*tp->t_linesw->l_poll)(tp, events, l);
}

struct tty *
sscomtty(dev_t dev)
{
        struct sscom_softc *sc = device_lookup_private(&sscom_cd, SSCOMUNIT(dev));
        struct tty *tp = sc->sc_tty;

        return tp;
}

int
sscomioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
{
        struct sscom_softc *sc = device_lookup_private(&sscom_cd, SSCOMUNIT(dev));
        struct tty *tp = sc->sc_tty;
        int error;
        int s;

        if (SSCOM_ISALIVE(sc) == 0)
                return EIO;

        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;

        error = 0;

        s = splserial();
        SSCOM_LOCK(sc); 

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

        case TIOCCBRK:
                sscom_break(sc, 0);
                break;

        case TIOCSDTR:
                sscom_modem(sc, 1);
                break;

        case TIOCCDTR:
                sscom_modem(sc, 0);
                break;

        case TIOCGFLAGS:
                *(int *)data = sc->sc_swflags;
                break;

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

        case TIOCMSET:
        case TIOCMBIS:
        case TIOCMBIC:
                tiocm_to_sscom(sc, cmd, *(int *)data);
                break;

        case TIOCMGET:
                *(int *)data = sscom_to_tiocm(sc);
                break;

        default:
                error = EPASSTHROUGH;
                break;
        }

        SSCOM_UNLOCK(sc);
        splx(s);

        if (sscom_debug)
                sscomstatus(sc, "sscomioctl ");

        return error;
}

integrate void
sscom_schedrx(struct sscom_softc *sc)
{

        sc->sc_rx_ready = 1;

        /* Wake up the poller. */
        softint_schedule(sc->sc_si);
}

static void
sscom_break(struct sscom_softc *sc, int onoff)
{

        if (onoff)
                SET(sc->sc_ucon, UCON_SBREAK);
        else
                CLR(sc->sc_ucon, UCON_SBREAK);

        if (!sc->sc_heldchange) {
                if (sc->sc_tx_busy) {
                        sc->sc_heldtbc = sc->sc_tbc;
                        sc->sc_tbc = 0;
                        sc->sc_heldchange = 1;
                } else
                        sscom_loadchannelregs(sc);
        }
}

static void
sscom_modem(struct sscom_softc *sc, int onoff)
{
        if (onoff)
                SET(sc->sc_umcon, UMCON_DTR);
        else
                CLR(sc->sc_umcon, UMCON_DTR);

        if (!sc->sc_heldchange) {
                if (sc->sc_tx_busy) {
                        sc->sc_heldtbc = sc->sc_tbc;
                        sc->sc_tbc = 0;
                        sc->sc_heldchange = 1;
                } else
                        sscom_loadchannelregs(sc);
        }
}

static void
tiocm_to_sscom(struct sscom_softc *sc, u_long how, int ttybits)
{
        u_char sscombits;

        sscombits = 0;
        if (ISSET(ttybits, TIOCM_DTR))
                sscombits = UMCON_DTR;
        if (ISSET(ttybits, TIOCM_RTS))
                SET(sscombits, UMCON_RTS);
 
        switch (how) {
        case TIOCMBIC:
                CLR(sc->sc_umcon, sscombits);
                break;

        case TIOCMBIS:
                SET(sc->sc_umcon, sscombits);
                break;

        case TIOCMSET:
                CLR(sc->sc_umcon, UMCON_DTR);
                SET(sc->sc_umcon, sscombits);
                break;
        }

        if (!sc->sc_heldchange) {
                if (sc->sc_tx_busy) {
                        sc->sc_heldtbc = sc->sc_tbc;
                        sc->sc_tbc = 0;
                        sc->sc_heldchange = 1;
                } else
                        sscom_loadchannelregs(sc);
        }
}

static int
sscom_to_tiocm(struct sscom_softc *sc)
{
        u_char sscombits;
        int ttybits = 0;

        sscombits = sc->sc_umcon;
#if 0
        if (ISSET(sscombits, MCR_DTR))
                SET(ttybits, TIOCM_DTR);
#endif
        if (ISSET(sscombits, UMCON_RTS))
                SET(ttybits, TIOCM_RTS);

        sscombits = sc->sc_msts;
        if (ISSET(sscombits, MSTS_DCD))
                SET(ttybits, TIOCM_CD);
        if (ISSET(sscombits, MSTS_DSR))
                SET(ttybits, TIOCM_DSR);
        if (ISSET(sscombits, MSTS_CTS))
                SET(ttybits, TIOCM_CTS);

        if (sc->sc_ucon != 0)
                SET(ttybits, TIOCM_LE);

        return ttybits;
}

static int
cflag2lcr(tcflag_t cflag)
{
        u_char lcr = ULCON_PARITY_NONE;

        switch (cflag & (PARENB|PARODD)) {
        case PARENB|PARODD: lcr = ULCON_PARITY_ODD; break;
        case PARENB: lcr = ULCON_PARITY_EVEN;
        }

        switch (ISSET(cflag, CSIZE)) {
        case CS5:
                SET(lcr, ULCON_LENGTH_5);
                break;
        case CS6:
                SET(lcr, ULCON_LENGTH_6);
                break;
        case CS7:
                SET(lcr, ULCON_LENGTH_7);
                break;
        case CS8:
                SET(lcr, ULCON_LENGTH_8);
                break;
        }
        if (ISSET(cflag, CSTOPB))
                SET(lcr, ULCON_STOP);

        return lcr;
}

int
sscomparam(struct tty *tp, struct termios *t)
{
        struct sscom_softc *sc = device_lookup_private(&sscom_cd, SSCOMUNIT(tp->t_dev));
        int ospeed;
        u_char lcr;
        int s;

        if (SSCOM_ISALIVE(sc) == 0)
                return EIO;

        ospeed = sscomspeed(t->c_ospeed, sc->sc_frequency);

        /* Check requested parameters. */
        if (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(sc->sc_swflags, TIOCFLAG_SOFTCAR) ||
            ISSET(sc->sc_hwflags, SSCOM_HW_CONSOLE)) {
                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;

        lcr = cflag2lcr(t->c_cflag);

        s = splserial();
        SSCOM_LOCK(sc); 

        sc->sc_ulcon = lcr;

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

        /*
         * Set the flow control pins depending on the current flow control
         * mode.
         */
        if (ISSET(t->c_cflag, CRTSCTS)) {
                sc->sc_mcr_dtr = UMCON_DTR;
                sc->sc_mcr_rts = UMCON_RTS;
                sc->sc_msr_cts = MSTS_CTS;
        }
        else if (ISSET(t->c_cflag, MDMBUF)) {
                /*
                 * For DTR/DCD flow control, make sure we don't toggle DTR for
                 * carrier detection.
                 */
                sc->sc_mcr_dtr = 0;
                sc->sc_mcr_rts = UMCON_DTR;
                sc->sc_msr_cts = MSTS_DCD;
        } 
        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.
                 */
                sc->sc_mcr_dtr = UMCON_DTR | UMCON_RTS;
                sc->sc_mcr_rts = 0;
                sc->sc_msr_cts = 0;
                if (ISSET(sc->sc_umcon, UMCON_DTR))
                        SET(sc->sc_umcon, UMCON_RTS);
                else
                        CLR(sc->sc_umcon, UMCON_RTS);
        }
        sc->sc_msr_mask = sc->sc_msr_cts | sc->sc_msr_dcd;

        if (ospeed == 0)
                CLR(sc->sc_umcon, sc->sc_mcr_dtr);
        else
                SET(sc->sc_umcon, sc->sc_mcr_dtr);

        sc->sc_ubrdiv = ospeed;

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

        if (!sc->sc_heldchange) {
                if (sc->sc_tx_busy) {
                        sc->sc_heldtbc = sc->sc_tbc;
                        sc->sc_tbc = 0;
                        sc->sc_heldchange = 1;
                } else
                        sscom_loadchannelregs(sc);
        }

        if (!ISSET(t->c_cflag, CHWFLOW)) {
                /* Disable the high water mark. */
                sc->sc_r_hiwat = 0;
                sc->sc_r_lowat = 0;
                if (ISSET(sc->sc_rx_flags, RX_TTY_OVERFLOWED)) {
                        CLR(sc->sc_rx_flags, RX_TTY_OVERFLOWED);
                        sscom_schedrx(sc);
                }
                if (ISSET(sc->sc_rx_flags, RX_TTY_BLOCKED|RX_IBUF_BLOCKED)) {
                        CLR(sc->sc_rx_flags, RX_TTY_BLOCKED|RX_IBUF_BLOCKED);
                        sscom_hwiflow(sc);
                }
        } else {
                sc->sc_r_hiwat = sscom_rbuf_hiwat;
                sc->sc_r_lowat = sscom_rbuf_lowat;
        }

        SSCOM_UNLOCK(sc);
        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(sc->sc_msts, MSTS_DCD));

        if (sscom_debug)
                sscomstatus(sc, "sscomparam ");

        if (!ISSET(t->c_cflag, CHWFLOW)) {
                if (sc->sc_tx_stopped) {
                        sc->sc_tx_stopped = 0;
                        sscomstart(tp);
                }
        }

        return 0;
}

static void
sscom_iflush(struct sscom_softc *sc)
{
        bus_space_tag_t iot = sc->sc_iot;
        bus_space_handle_t ioh = sc->sc_ioh;
        int timo;


        timo = 50000;
        /* flush any pending I/O */
        while ( sscom_rxrdy(iot, ioh) && --timo)
                (void)sscom_getc(iot,ioh);
#ifdef DIAGNOSTIC
        if (!timo)
                printf("%s: sscom_iflush timeout\n", device_xname(sc->sc_dev));
#endif
}

static void
sscom_loadchannelregs(struct sscom_softc *sc)
{
        bus_space_tag_t iot = sc->sc_iot;
        bus_space_handle_t ioh = sc->sc_ioh;

        /* XXXXX necessary? */
        sscom_iflush(sc);

        bus_space_write_2(iot, ioh, SSCOM_UCON, 0);

#if 0
        if (ISSET(sc->sc_hwflags, COM_HW_FLOW)) {
                bus_space_write_1(iot, ioh, com_lcr, LCR_EERS);
                bus_space_write_1(iot, ioh, com_efr, sc->sc_efr);
        }
#endif

        bus_space_write_2(iot, ioh, SSCOM_UBRDIV, sc->sc_ubrdiv);
        bus_space_write_1(iot, ioh, SSCOM_ULCON, sc->sc_ulcon);
        sc->sc_set_modem_control(sc);
        bus_space_write_2(iot, ioh, SSCOM_UCON, sc->sc_ucon);
}

static int
sscomhwiflow(struct tty *tp, int block)
{
        struct sscom_softc *sc = device_lookup_private(&sscom_cd, SSCOMUNIT(tp->t_dev));
        int s;

        if (SSCOM_ISALIVE(sc) == 0)
                return 0;

        if (sc->sc_mcr_rts == 0)
                return 0;

        s = splserial();
        SSCOM_LOCK(sc);
        
        if (block) {
                if (!ISSET(sc->sc_rx_flags, RX_TTY_BLOCKED)) {
                        SET(sc->sc_rx_flags, RX_TTY_BLOCKED);
                        sscom_hwiflow(sc);
                }
        } else {
                if (ISSET(sc->sc_rx_flags, RX_TTY_OVERFLOWED)) {
                        CLR(sc->sc_rx_flags, RX_TTY_OVERFLOWED);
                        sscom_schedrx(sc);
                }
                if (ISSET(sc->sc_rx_flags, RX_TTY_BLOCKED)) {
                        CLR(sc->sc_rx_flags, RX_TTY_BLOCKED);
                        sscom_hwiflow(sc);
                }
        }

        SSCOM_UNLOCK(sc);
        splx(s);
        return 1;
}
        
/*
 * (un)block input via hw flowcontrol
 */
static void
sscom_hwiflow(struct sscom_softc *sc)
{
        if (sc->sc_mcr_rts == 0)
                return;

        if (ISSET(sc->sc_rx_flags, RX_ANY_BLOCK)) {
                CLR(sc->sc_umcon, sc->sc_mcr_rts);
                CLR(sc->sc_mcr_active, sc->sc_mcr_rts);
        } else {
                SET(sc->sc_umcon, sc->sc_mcr_rts);
                SET(sc->sc_mcr_active, sc->sc_mcr_rts);
        }
        sc->sc_set_modem_control(sc);
}


void
sscomstart(struct tty *tp)
{
        struct sscom_softc *sc = device_lookup_private(&sscom_cd, SSCOMUNIT(tp->t_dev));
        int s;

        if (SSCOM_ISALIVE(sc) == 0)
                return;

        s = spltty();
        if (ISSET(tp->t_state, TS_BUSY | TS_TIMEOUT | TS_TTSTOP))
                goto out;
        if (sc->sc_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();
                SSCOM_LOCK(sc);

                sc->sc_tba = tba;
                sc->sc_tbc = tbc;
        }

        SET(tp->t_state, TS_BUSY);
        sc->sc_tx_busy = 1;

        /* Output the first chunk of the contiguous buffer. */
        sscom_output_chunk(sc);

        /* Enable transmit completion interrupts if necessary. */
        if ((sc->sc_hwflags & SSCOM_HW_TXINT) == 0)
                sscom_enable_txint(sc);

        SSCOM_UNLOCK(sc);
out:
        splx(s);
        return;
}

/*
 * Stop output on a line.
 */
void
sscomstop(struct tty *tp, int flag)
{
        struct sscom_softc *sc = device_lookup_private(&sscom_cd, SSCOMUNIT(tp->t_dev));
        int s;

        s = splserial();
        SSCOM_LOCK(sc);
        if (ISSET(tp->t_state, TS_BUSY)) {
                /* Stop transmitting at the next chunk. */
                sc->sc_tbc = 0;
                sc->sc_heldtbc = 0;
                if (!ISSET(tp->t_state, TS_TTSTOP))
                        SET(tp->t_state, TS_FLUSH);
        }
        SSCOM_UNLOCK(sc);       
        splx(s);
}

void
sscomdiag(void *arg)
{
        struct sscom_softc *sc = arg;
        int overflows, floods;
        int s;

        s = splserial();
        SSCOM_LOCK(sc);
        overflows = sc->sc_overflows;
        sc->sc_overflows = 0;
        floods = sc->sc_floods;
        sc->sc_floods = 0;
        sc->sc_errors = 0;
        SSCOM_UNLOCK(sc);
        splx(s);

        log(LOG_WARNING, "%s: %d silo overflow%s, %d ibuf flood%s\n",
            device_xname(sc->sc_dev),
            overflows, overflows == 1 ? "" : "s",
            floods, floods == 1 ? "" : "s");
}

integrate void
sscom_rxsoft(struct sscom_softc *sc, struct tty *tp)
{
        int (*rint) (int, struct tty *) = tp->t_linesw->l_rint;
        u_char *get, *end;
        u_int cc, scc;
        u_char rsr;
        int code;
        int s;

        end = sc->sc_ebuf;
        get = sc->sc_rbget;
        scc = cc = sscom_rbuf_size - sc->sc_rbavail;

        if (cc == sscom_rbuf_size) {
                sc->sc_floods++;
                if (sc->sc_errors++ == 0)
                        callout_reset(&sc->sc_diag_callout, 60 * hz,
                            sscomdiag, sc);
        }

        while (cc) {
                code = get[0];
                rsr = get[1];
                if (rsr) {
                        if (ISSET(rsr, UERSTAT_OVERRUN)) {
                                sc->sc_overflows++;
                                if (sc->sc_errors++ == 0)
                                        callout_reset(&sc->sc_diag_callout,
                                            60 * hz, sscomdiag, sc);
                        }
                        if (ISSET(rsr, UERSTAT_BREAK | UERSTAT_FRAME))
                                SET(code, TTY_FE);
                        if (ISSET(rsr, UERSTAT_PARITY))
                                SET(code, TTY_PE);
                }
                if ((*rint)(code, tp) == -1) {
                        /*
                         * The line discipline's buffer is out of space.
                         */
                        if (!ISSET(sc->sc_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 -= sscom_rbuf_size << 1;
                                cc = 0;
                        } else {
                                /*
                                 * Don't schedule any more receive processing
                                 * until the line discipline tells us there's
                                 * space available (through sscomhwiflow()).
                                 * Leave the rest of the data in the input
                                 * buffer.
                                 */
                                SET(sc->sc_rx_flags, RX_TTY_OVERFLOWED);
                        }
                        break;
                }
                get += 2;
                if (get >= end)
                        get = sc->sc_rbuf;
                cc--;
        }

        if (cc != scc) {
                sc->sc_rbget = get;
                s = splserial();
                SSCOM_LOCK(sc);
                
                cc = sc->sc_rbavail += scc - cc;
                /* Buffers should be ok again, release possible block. */
                if (cc >= sc->sc_r_lowat) {
                        if (ISSET(sc->sc_rx_flags, RX_IBUF_OVERFLOWED)) {
                                CLR(sc->sc_rx_flags, RX_IBUF_OVERFLOWED);
                                sscom_enable_rxint(sc);
                                sc->sc_ucon |= UCON_ERRINT;
                                bus_space_write_2(sc->sc_iot, sc->sc_ioh, SSCOM_UCON, 
                                                  sc->sc_ucon);

                        }
                        if (ISSET(sc->sc_rx_flags, RX_IBUF_BLOCKED)) {
                                CLR(sc->sc_rx_flags, RX_IBUF_BLOCKED);
                                sscom_hwiflow(sc);
                        }
                }
                SSCOM_UNLOCK(sc);
                splx(s);
        }
}

integrate void
sscom_txsoft(struct sscom_softc *sc, 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)(sc->sc_tba - tp->t_outq.c_cf));
        (*tp->t_linesw->l_start)(tp);
}

integrate void
sscom_stsoft(struct sscom_softc *sc, struct tty *tp)
{
        u_char msr, delta;
        int s;

        s = splserial();
        SSCOM_LOCK(sc);
        msr = sc->sc_msts;
        delta = sc->sc_msr_delta;
        sc->sc_msr_delta = 0;
        SSCOM_UNLOCK(sc);       
        splx(s);

        if (ISSET(delta, sc->sc_msr_dcd)) {
                /*
                 * Inform the tty layer that carrier detect changed.
                 */
                (void) (*tp->t_linesw->l_modem)(tp, ISSET(msr, MSTS_DCD));
        }

        if (ISSET(delta, sc->sc_msr_cts)) {
                /* Block or unblock output according to flow control. */
                if (ISSET(msr, sc->sc_msr_cts)) {
                        sc->sc_tx_stopped = 0;
                        (*tp->t_linesw->l_start)(tp);
                } else {
                        sc->sc_tx_stopped = 1;
                }
        }

        if (sscom_debug)
                sscomstatus(sc, "sscom_stsoft");
}

void
sscomsoft(void *arg)
{
        struct sscom_softc *sc = arg;
        struct tty *tp;

        if (SSCOM_ISALIVE(sc) == 0)
                return;

        {
                tp = sc->sc_tty;
                
                if (sc->sc_rx_ready) {
                        sc->sc_rx_ready = 0;
                        sscom_rxsoft(sc, tp);
                }

                if (sc->sc_st_check) {
                        sc->sc_st_check = 0;
                        sscom_stsoft(sc, tp);
                }

                if (sc->sc_tx_done) {
                        sc->sc_tx_done = 0;
                        sscom_txsoft(sc, tp);
                }
        }
}


int
sscomrxintr(void *arg)
{
        struct sscom_softc *sc = arg;
        bus_space_tag_t iot = sc->sc_iot;
        bus_space_handle_t ioh = sc->sc_ioh;
        u_char *put, *end;
        u_int cc;

        if (SSCOM_ISALIVE(sc) == 0)
                return 0;

        SSCOM_LOCK(sc);

        end = sc->sc_ebuf;
        put = sc->sc_rbput;
        cc = sc->sc_rbavail;

        do {
                u_char  msts, delta;
                u_char  uerstat;
                uint16_t ufstat;

                ufstat = bus_space_read_2(iot, ioh, SSCOM_UFSTAT);

                /* XXX: break interrupt with no character? */

                if ( (ufstat & (UFSTAT_RXCOUNT|UFSTAT_RXFULL)) &&
                    !ISSET(sc->sc_rx_flags, RX_IBUF_OVERFLOWED)) {

                        while (cc > 0) {
                                int cn_trapped = 0;

                                /* get status and received character.
                                   read status register first */
                                uerstat = sscom_geterr(iot, ioh);
                                put[0] = sscom_getc(iot, ioh);

                                if (ISSET(uerstat, UERSTAT_BREAK)) {
                                        int con_trapped = 0;
                                        cn_check_magic(sc->sc_tty->t_dev,
                                            CNC_BREAK, sscom_cnm_state);
                                        if (con_trapped)
                                                continue;
#if defined(KGDB)
                                        if (ISSET(sc->sc_hwflags,
                                            SSCOM_HW_KGDB)) {
                                                kgdb_connect(1);
                                                continue;
                                        }
#endif
                                }

                                put[1] = uerstat;
                                cn_check_magic(sc->sc_tty->t_dev,
                                               put[0], sscom_cnm_state);
                                if (!cn_trapped) {
                                        put += 2;
                                        if (put >= end)
                                                put = sc->sc_rbuf;
                                        cc--;
                                }

                                ufstat = bus_space_read_2(iot, ioh, SSCOM_UFSTAT);
                                if ( (ufstat & (UFSTAT_RXFULL|UFSTAT_RXCOUNT)) == 0 )
                                        break;
                        }

                        /*
                         * Current string of incoming characters ended because
                         * no more data was available or we ran out of space.
                         * Schedule a receive event if any data was received.
                         * If we're out of space, turn off receive interrupts.
                         */
                        sc->sc_rbput = put;
                        sc->sc_rbavail = cc;
                        if (!ISSET(sc->sc_rx_flags, RX_TTY_OVERFLOWED))
                                sc->sc_rx_ready = 1;

                        /*
                         * See if we are in danger of overflowing a buffer. If
                         * so, use hardware flow control to ease the pressure.
                         */
                        if (!ISSET(sc->sc_rx_flags, RX_IBUF_BLOCKED) &&
                            cc < sc->sc_r_hiwat) {
                                SET(sc->sc_rx_flags, RX_IBUF_BLOCKED);
                                sscom_hwiflow(sc);
                        }

                        /*
                         * If we're out of space, disable receive interrupts
                         * until the queue has drained a bit.
                         */
                        if (!cc) {
                                SET(sc->sc_rx_flags, RX_IBUF_OVERFLOWED);
                                sscom_disable_rxint(sc);
                                sc->sc_ucon &= ~UCON_ERRINT;
                                bus_space_write_2(iot, ioh, SSCOM_UCON, sc->sc_ucon);
                        }
                }


                msts = sc->sc_read_modem_status(sc);
                delta = msts ^ sc->sc_msts;
                sc->sc_msts = msts;

#ifdef notyet
                /*
                 * Pulse-per-second (PSS) signals on edge of DCD?
                 * Process these even if line discipline is ignoring DCD.
                 */
                if (delta & sc->sc_ppsmask) {
                        struct timeval tv;
                        if ((msr & sc->sc_ppsmask) == sc->sc_ppsassert) {
                                /* XXX nanotime() */
                                microtime(&tv);
                                TIMEVAL_TO_TIMESPEC(&tv, 
                                    &sc->ppsinfo.assert_timestamp);
                                if (sc->ppsparam.mode & PPS_OFFSETASSERT) {
                                        timespecadd(&sc->ppsinfo.assert_timestamp,
                                            &sc->ppsparam.assert_offset,
                                                    &sc->ppsinfo.assert_timestamp);
                                }

#ifdef PPS_SYNC
                                if (sc->ppsparam.mode & PPS_HARDPPSONASSERT)
                                        hardpps(&tv, tv.tv_usec);
#endif
                                sc->ppsinfo.assert_sequence++;
                                sc->ppsinfo.current_mode = sc->ppsparam.mode;

                        } else if ((msr & sc->sc_ppsmask) == sc->sc_ppsclear) {
                                /* XXX nanotime() */
                                microtime(&tv);
                                TIMEVAL_TO_TIMESPEC(&tv, 
                                    &sc->ppsinfo.clear_timestamp);
                                if (sc->ppsparam.mode & PPS_OFFSETCLEAR) {
                                        timespecadd(&sc->ppsinfo.clear_timestamp,
                                            &sc->ppsparam.clear_offset,
                                            &sc->ppsinfo.clear_timestamp);
                                }

#ifdef PPS_SYNC
                                if (sc->ppsparam.mode & PPS_HARDPPSONCLEAR)
                                        hardpps(&tv, tv.tv_usec);
#endif
                                sc->ppsinfo.clear_sequence++;
                                sc->ppsinfo.current_mode = sc->ppsparam.mode;
                        }
                }
#endif

                /*
                 * Process normal status changes
                 */
                if (ISSET(delta, sc->sc_msr_mask)) {
                        SET(sc->sc_msr_delta, delta);

                        /*
                         * Stop output immediately if we lose the output
                         * flow control signal or carrier detect.
                         */
                        if (ISSET(~msts, sc->sc_msr_mask)) {
                                sc->sc_tbc = 0;
                                sc->sc_heldtbc = 0;
#ifdef SSCOM_DEBUG
                                if (sscom_debug)
                                        sscomstatus(sc, "sscomintr  ");
#endif
                        }

                        sc->sc_st_check = 1;
                }

                /* 
                 * Done handling any receive interrupts. 
                 */

                /*
                 * If we've delayed a parameter change, do it
                 * now, and restart * output.
                 */
                if ((ufstat & UFSTAT_TXCOUNT) == 0) {
                        /* XXX: we should check transmitter empty also */

                        if (sc->sc_heldchange) {
                                sscom_loadchannelregs(sc);
                                sc->sc_heldchange = 0;
                                sc->sc_tbc = sc->sc_heldtbc;
                                sc->sc_heldtbc = 0;
                        }
                }


        } while (0);

        SSCOM_UNLOCK(sc);

        /* Wake up the poller. */
        softint_schedule(sc->sc_si);

#ifdef RND_COM
        rnd_add_uint32(&sc->rnd_source, iir | rsr);
#endif

        return 1;
}

int
sscomtxintr(void *arg)
{
        struct sscom_softc *sc = arg;
        bus_space_tag_t iot = sc->sc_iot;
        bus_space_handle_t ioh = sc->sc_ioh;
        uint16_t ufstat;

        if (SSCOM_ISALIVE(sc) == 0)
                return 0;

        SSCOM_LOCK(sc);

        ufstat = bus_space_read_2(iot, ioh, SSCOM_UFSTAT);

        /*
         * If we've delayed a parameter change, do it
         * now, and restart * output.
         */
        if (sc->sc_heldchange && (ufstat & UFSTAT_TXCOUNT) == 0) {
                /* XXX: we should check transmitter empty also */
                sscom_loadchannelregs(sc);
                sc->sc_heldchange = 0;
                sc->sc_tbc = sc->sc_heldtbc;
                sc->sc_heldtbc = 0;
        }

        /*
         * See if data can be transmitted as well. Schedule tx
         * done event if no data left and tty was marked busy.
         */
        if (!ISSET(ufstat,UFSTAT_TXFULL)) {
                /* 
                 * Output the next chunk of the contiguous
                 * buffer, if any.
                 */
                if (sc->sc_tbc > 0) {
                        __sscom_output_chunk(sc, ufstat);
                }
                else {
                        /*
                         * Disable transmit sscompletion
                         * interrupts if necessary.
                         */
                        if (sc->sc_hwflags & SSCOM_HW_TXINT)
                                sscom_disable_txint(sc);
                        if (sc->sc_tx_busy) {
                                sc->sc_tx_busy = 0;
                                sc->sc_tx_done = 1;
                        }
                }
        }

        SSCOM_UNLOCK(sc);

        /* Wake up the poller. */
        softint_schedule(sc->sc_si);

#ifdef RND_COM
        rnd_add_uint32(&sc->rnd_source, iir | rsr);
#endif

        return 1;
}


#if defined(KGDB) || defined(SSCOM0CONSOLE) || defined(SSCOM1CONSOLE)
/*
 * Initialize UART for use as console or KGDB line.
 */
static int
sscom_init(bus_space_tag_t iot, const struct sscom_uart_info *config,
    int rate, int frequency, tcflag_t cflag, bus_space_handle_t *iohp)
{
        bus_space_handle_t ioh;
        bus_addr_t iobase = config->iobase;

        if (bus_space_map(iot, iobase, SSCOM_SIZE, 0, &ioh))
                return ENOMEM; /* ??? */

        bus_space_write_2(iot, ioh, SSCOM_UCON, 0);
        bus_space_write_1(iot, ioh, SSCOM_UFCON, 
#ifdef SSCOM_S3C2440
            UFCON_TXTRIGGER_16 | UFCON_RXTRIGGER_16 |
#else
            UFCON_TXTRIGGER_8 | UFCON_RXTRIGGER_8 |
#endif
            UFCON_TXFIFO_RESET | UFCON_RXFIFO_RESET |
            UFCON_FIFO_ENABLE );
        /* tx/rx fifo reset are auto-cleared */

        rate = sscomspeed(rate, frequency);
        bus_space_write_2(iot, ioh, SSCOM_UBRDIV, rate);
        bus_space_write_2(iot, ioh, SSCOM_ULCON, cflag2lcr(cflag));

        /* enable UART */
        bus_space_write_2(iot, ioh, SSCOM_UCON, 
            UCON_TXMODE_INT|UCON_RXMODE_INT);
        bus_space_write_2(iot, ioh, SSCOM_UMCON, UMCON_RTS);

        *iohp = ioh;
        return 0;
}

#endif

#if defined(SSCOM0CONSOLE) || defined(SSCOM1CONSOLE)
/*
 * Following are all routines needed for SSCOM to act as console
 */
struct consdev sscomcons = {
        NULL, NULL, sscomcngetc, sscomcnputc, sscomcnpollc, NULL,
        NULL, NULL, NODEV, CN_NORMAL
};


int
sscom_cnattach(bus_space_tag_t iot, const struct sscom_uart_info *config,
    int rate, int frequency, tcflag_t cflag)
{
        int res;

        res = sscom_init(iot, config, rate, frequency, cflag, &sscomconsioh);
        if (res)
                return res;

        cn_tab = &sscomcons;
        cn_init_magic(&sscom_cnm_state);
        cn_set_magic("\047\001"); /* default magic is BREAK */

        sscomconstag = iot;
        sscomconsunit = config->unit;
        sscomconsrate = rate;
        sscomconscflag = cflag;

        return 0;
}

void
sscom_cndetach(void)
{
        bus_space_unmap(sscomconstag, sscomconsioh, SSCOM_SIZE);
        sscomconstag = NULL;

        cn_tab = NULL;
}

/*
 * The read-ahead code is so that you can detect pending in-band
 * cn_magic in polled mode while doing output rather than having to
 * wait until the kernel decides it needs input.
 */

#define MAX_READAHEAD   20
static int sscom_readahead[MAX_READAHEAD];
static int sscom_readaheadcount = 0;

int
sscomcngetc(dev_t dev)
{
        int s = splserial();
        u_char __attribute__((__unused__)) stat;
        u_char c;

        /* got a character from reading things earlier */
        if (sscom_readaheadcount > 0) {
                int i;

                c = sscom_readahead[0];
                for (i = 1; i < sscom_readaheadcount; i++) {
                        sscom_readahead[i-1] = sscom_readahead[i];
                }
                sscom_readaheadcount--;
                splx(s);
                return c;
        }

        /* block until a character becomes available */
        while (!sscom_rxrdy(sscomconstag, sscomconsioh))
                ;

        c = sscom_getc(sscomconstag, sscomconsioh);
        stat = sscom_geterr(sscomconstag, sscomconsioh);
        {
                int cn_trapped __unused = 0;
                if (!db_active)
                        cn_check_magic(dev, c, sscom_cnm_state);
        }
        splx(s);
        return c;
}

/*
 * Console kernel output character routine.
 */
void
sscomcnputc(dev_t dev, int c)
{
        int s = splserial();
        int timo;

        int cin;
        int __attribute__((__unused__)) stat;
        if (sscom_readaheadcount < MAX_READAHEAD && 
            sscom_rxrdy(sscomconstag, sscomconsioh)) {
            
                int __attribute__((__unused__))cn_trapped = 0;
                cin = sscom_getc(sscomconstag, sscomconsioh);
                stat = sscom_geterr(sscomconstag, sscomconsioh);
                cn_check_magic(dev, cin, sscom_cnm_state);
                sscom_readahead[sscom_readaheadcount++] = cin;
        }

        /* wait for any pending transmission to finish */
        timo = 150000;
        while (ISSET(bus_space_read_2(sscomconstag, sscomconsioh, SSCOM_UFSTAT), 
                   UFSTAT_TXFULL) && --timo)
                continue;

        bus_space_write_1(sscomconstag, sscomconsioh, SSCOM_UTXH, c);
        SSCOM_BARRIER(sscomconstag, sscomconsioh, BR | BW);

#if 0   
        /* wait for this transmission to complete */
        timo = 1500000;
        while (!ISSET(bus_space_read_1(sscomconstag, sscomconsioh, SSCOM_UTRSTAT), 
                   UTRSTAT_TXEMPTY) && --timo)
                continue;
#endif
        splx(s);
}

void
sscomcnpollc(dev_t dev, int on)
{

        sscom_readaheadcount = 0;
}

#endif /* SSCOM0CONSOLE||SSCOM1CONSOLE */

#ifdef KGDB
int
sscom_kgdb_attach(bus_space_tag_t iot, const struct sscom_uart_info *config,
    int rate, int frequency, tcflag_t cflag)
{
        int res;

        if (iot == sscomconstag && config->unit == sscomconsunit) {
                printf( "console==kgdb_port (%d): kgdb disabled\n", sscomconsunit);
                return EBUSY; /* cannot share with console */
        }

        res = sscom_init(iot, config, rate, frequency, cflag, &sscom_kgdb_ioh);
        if (res)
                return res;

        kgdb_attach(sscom_kgdb_getc, sscom_kgdb_putc, NULL);
        kgdb_dev = 123; /* unneeded, only to satisfy some tests */

        sscom_kgdb_iot = iot;
        sscom_kgdb_unit = config->unit;

        return 0;
}

/* ARGSUSED */
int
sscom_kgdb_getc(void *arg)
{
        int c, stat;

        /* block until a character becomes available */
        while (!sscom_rxrdy(sscom_kgdb_iot, sscom_kgdb_ioh))
                ;

        c = sscom_getc(sscom_kgdb_iot, sscom_kgdb_ioh);
        stat = sscom_geterr(sscom_kgdb_iot, sscom_kgdb_ioh);

        return c;
}

/* ARGSUSED */
void
sscom_kgdb_putc(void *arg, int c)
{
        int timo;

        /* wait for any pending transmission to finish */
        timo = 150000;
        while (ISSET(bus_space_read_2(sscom_kgdb_iot, sscom_kgdb_ioh,
            SSCOM_UFSTAT), UFSTAT_TXFULL) && --timo)
                continue;

        bus_space_write_1(sscom_kgdb_iot, sscom_kgdb_ioh, SSCOM_UTXH, c);
        SSCOM_BARRIER(sscom_kgdb_iot, sscom_kgdb_ioh, BR | BW);

#if 0   
        /* wait for this transmission to complete */
        timo = 1500000;
        while (!ISSET(bus_space_read_1(sscom_kgdb_iot, sscom_kgdb_ioh,
            SSCOM_UTRSTAT), UTRSTAT_TXEMPTY) && --timo)
                continue;
#endif
}
#endif /* KGDB */

/* helper function to identify the sscom ports used by
 console or KGDB (and not yet autoconf attached) */
int
sscom_is_console(bus_space_tag_t iot, int unit,
    bus_space_handle_t *ioh)
{
        bus_space_handle_t help;

        if (!sscomconsattached &&
            iot == sscomconstag && unit == sscomconsunit)
                help = sscomconsioh;
#ifdef KGDB
        else if (!sscom_kgdb_attached &&
            iot == sscom_kgdb_iot && unit == sscom_kgdb_unit)
                help = sscom_kgdb_ioh;
#endif
        else
                return 0;

        if (ioh)
                *ioh = help;
        return 1;
}