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[netbsd-mini2440.git] / sys / arch / evbarm / dev / plcom.c

/*      $NetBSD: plcom.c,v 1.30 2009/11/21 20:32:28 rmind Exp $ */

/*-
 * Copyright (c) 2001 ARM Ltd
 * 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. The name of the company may not be used to endorse or promote
 *    products derived from this software without specific prior written
 *    permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR 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) 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
 */

/*
 * COM driver for the Prime Cell PL010 UART, which is similar to the 16C550,
 * but has a completely different programmer's model.
 * Derived from the NS16550AF com driver.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: plcom.c,v 1.30 2009/11/21 20:32:28 rmind Exp $");

#include "opt_plcom.h"
#include "opt_ddb.h"
#include "opt_kgdb.h"
#include "opt_lockdebug.h"
#include "opt_multiprocessor.h"

#include "rnd.h"
#if NRND > 0 && defined(RND_COM)
#include <sys/rnd.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/malloc.h>
#include <sys/timepps.h>
#include <sys/vnode.h>
#include <sys/kauth.h>
#include <sys/intr.h>
#include <sys/bus.h>

#include <evbarm/dev/plcomreg.h>
#include <evbarm/dev/plcomvar.h>

#include <dev/cons.h>

static void plcom_enable_debugport (struct plcom_softc *);

void    plcom_config    (struct plcom_softc *);
void    plcom_shutdown  (struct plcom_softc *);
int     plcomspeed      (long, long);
static  u_char  cflag2lcr (tcflag_t);
int     plcomparam      (struct tty *, struct termios *);
void    plcomstart      (struct tty *);
int     plcomhwiflow    (struct tty *, int);

void    plcom_loadchannelregs (struct plcom_softc *);
void    plcom_hwiflow   (struct plcom_softc *);
void    plcom_break     (struct plcom_softc *, int);
void    plcom_modem     (struct plcom_softc *, int);
void    tiocm_to_plcom  (struct plcom_softc *, u_long, int);
int     plcom_to_tiocm  (struct plcom_softc *);
void    plcom_iflush    (struct plcom_softc *);

int     plcom_common_getc (dev_t, bus_space_tag_t, bus_space_handle_t);
void    plcom_common_putc (dev_t, bus_space_tag_t, bus_space_handle_t, int);

int     plcominit       (bus_space_tag_t, bus_addr_t, int, int, tcflag_t,
                            bus_space_handle_t *);

dev_type_open(plcomopen);
dev_type_close(plcomclose);
dev_type_read(plcomread);
dev_type_write(plcomwrite);
dev_type_ioctl(plcomioctl);
dev_type_stop(plcomstop);
dev_type_tty(plcomtty);
dev_type_poll(plcompoll);

int     plcomcngetc     (dev_t);
void    plcomcnputc     (dev_t, int);
void    plcomcnpollc    (dev_t, int);

#define integrate       static inline
void    plcomsoft       (void *);
integrate void plcom_rxsoft     (struct plcom_softc *, struct tty *);
integrate void plcom_txsoft     (struct plcom_softc *, struct tty *);
integrate void plcom_stsoft     (struct plcom_softc *, struct tty *);
integrate void plcom_schedrx    (struct plcom_softc *);
void    plcomdiag               (void *);

extern struct cfdriver plcom_cd;

const struct cdevsw plcom_cdevsw = {
        plcomopen, plcomclose, plcomread, plcomwrite, plcomioctl,
        plcomstop, plcomtty, plcompoll, nommap, ttykqfilter, D_TTY
};

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

/* Stop input when 3/4 of the ring is full; restart when only 1/4 is full. */
u_int plcom_rbuf_hiwat = (PLCOM_RING_SIZE * 1) / 4;
u_int plcom_rbuf_lowat = (PLCOM_RING_SIZE * 3) / 4;

static int      plcomconsunit = -1;
static bus_space_tag_t plcomconstag;
static bus_space_handle_t plcomconsioh;
static int      plcomconsattached;
static int plcomconsrate;
static tcflag_t plcomconscflag;
static struct cnm_state plcom_cnm_state;

static int ppscap =
        PPS_TSFMT_TSPEC |
        PPS_CAPTUREASSERT | 
        PPS_CAPTURECLEAR |
#ifdef  PPS_SYNC 
        PPS_HARDPPSONASSERT | PPS_HARDPPSONCLEAR |
#endif  /* PPS_SYNC */
        PPS_OFFSETASSERT | PPS_OFFSETCLEAR;

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

static int plcom_kgdb_unit;
static bus_space_tag_t plcom_kgdb_iot;
static bus_space_handle_t plcom_kgdb_ioh;
static int plcom_kgdb_attached;

int     plcom_kgdb_getc (void *);
void    plcom_kgdb_putc (void *, int);
#endif /* KGDB */

#define PLCOMUNIT_MASK  0x7ffff
#define PLCOMDIALOUT_MASK       0x80000

#define PLCOMUNIT(x)    (minor(x) & PLCOMUNIT_MASK)
#define PLCOMDIALOUT(x) (minor(x) & PLCOMDIALOUT_MASK)

#define PLCOM_ISALIVE(sc)       ((sc)->enabled != 0 && \
                                 device_is_active(&(sc)->sc_dev))

#define BR      BUS_SPACE_BARRIER_READ
#define BW      BUS_SPACE_BARRIER_WRITE
#define PLCOM_BARRIER(t, h, f) bus_space_barrier((t), (h), 0, PLCOM_UART_SIZE, (f))

#define PLCOM_LOCK(sc) simple_lock(&(sc)->sc_lock)
#define PLCOM_UNLOCK(sc) simple_unlock(&(sc)->sc_lock)

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

        int x, err;

#if 0
        if (speed == 0)
                return 0;
#endif
        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 > PLCOM_TOLERANCE)
                return -1;
        return x;

#undef  divrnd
}

#ifdef PLCOM_DEBUG
int     plcom_debug = 0;

void plcomstatus (struct plcom_softc *, char *);
void
plcomstatus(struct plcom_softc *sc, char *str)
{
        struct tty *tp = sc->sc_tty;

        printf("%s: %s %sclocal  %sdcd %sts_carr_on %sdtr %stx_stopped\n",
            sc->sc_dev.dv_xname, str,
            ISSET(tp->t_cflag, CLOCAL) ? "+" : "-",
            ISSET(sc->sc_msr, MSR_DCD) ? "+" : "-",
            ISSET(tp->t_state, TS_CARR_ON) ? "+" : "-",
            ISSET(sc->sc_mcr, MCR_DTR) ? "+" : "-",
            sc->sc_tx_stopped ? "+" : "-");

        printf("%s: %s %scrtscts %scts %sts_ttstop  %srts %xrx_flags\n",
            sc->sc_dev.dv_xname, str,
            ISSET(tp->t_cflag, CRTSCTS) ? "+" : "-",
            ISSET(sc->sc_msr, MSR_CTS) ? "+" : "-",
            ISSET(tp->t_state, TS_TTSTOP) ? "+" : "-",
            ISSET(sc->sc_mcr, MCR_RTS) ? "+" : "-",
            sc->sc_rx_flags);
}
#endif

int
plcomprobe1(bus_space_tag_t iot, bus_space_handle_t ioh)
{
        int data;

        /* Disable the UART.  */
        bus_space_write_1(iot, ioh, plcom_cr, 0);
        /* Make sure the FIFO is off.  */
        bus_space_write_1(iot, ioh, plcom_lcr, LCR_8BITS);
        /* Disable interrupts.  */
        bus_space_write_1(iot, ioh, plcom_iir, 0);

        /* Make sure we swallow anything in the receiving register.  */
        data = bus_space_read_1(iot, ioh, plcom_dr);

        if (bus_space_read_1(iot, ioh, plcom_lcr) != LCR_8BITS)
                return 0;

        data = bus_space_read_1(iot, ioh, plcom_fr) & (FR_RXFF | FR_RXFE);

        if (data != FR_RXFE)
                return 0;

        return 1;
}

static void
plcom_enable_debugport(struct plcom_softc *sc)
{
        int s;

        /* Turn on line break interrupt, set carrier. */
        s = splserial();
        PLCOM_LOCK(sc);
        sc->sc_cr = CR_RIE | CR_RTIE | CR_UARTEN;
        bus_space_write_1(sc->sc_iot, sc->sc_ioh, plcom_cr, sc->sc_cr);
        SET(sc->sc_mcr, MCR_DTR | MCR_RTS);
        /* XXX device_unit() abuse */
        sc->sc_set_mcr(sc->sc_set_mcr_arg, device_unit(&sc->sc_dev),
            sc->sc_mcr);
        PLCOM_UNLOCK(sc);
        splx(s);
}

void
plcom_attach_subr(struct plcom_softc *sc)
{
        int unit = sc->sc_iounit;
        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);
        simple_lock_init(&sc->sc_lock);

        /* Disable interrupts before configuring the device. */
        sc->sc_cr = 0;

        if (plcomconstag && unit == plcomconsunit) {
                plcomconsattached = 1;

                plcomconstag = iot;
                plcomconsioh = ioh;

                /* Make sure the console is always "hardwired". */
                delay(1000);                    /* wait for output to finish */
                SET(sc->sc_hwflags, PLCOM_HW_CONSOLE);
                SET(sc->sc_swflags, TIOCFLAG_SOFTCAR);
                /* Must re-enable the console immediately, or we will
                   hang when trying to print.  */
                sc->sc_cr = CR_UARTEN;
        }

        bus_space_write_1(iot, ioh, plcom_cr, sc->sc_cr);

        /* The PL010 has a 16-byte fifo, but the tx interrupt triggers when
           there is space for 8 more bytes.  */
        sc->sc_fifolen = 8;
        printf("\n");

        if (ISSET(sc->sc_hwflags, PLCOM_HW_TXFIFO_DISABLE)) {
                sc->sc_fifolen = 1;
                printf("%s: txfifo disabled\n", sc->sc_dev.dv_xname);
        }

        if (sc->sc_fifolen > 1)
                SET(sc->sc_hwflags, PLCOM_HW_FIFO);

        tp = ttymalloc();
        tp->t_oproc = plcomstart;
        tp->t_param = plcomparam;
        tp->t_hwiflow = plcomhwiflow;

        sc->sc_tty = tp;
        sc->sc_rbuf = malloc(plcom_rbuf_size << 1, M_DEVBUF, M_NOWAIT);
        sc->sc_rbput = sc->sc_rbget = sc->sc_rbuf;
        sc->sc_rbavail = plcom_rbuf_size;
        if (sc->sc_rbuf == NULL) {
                printf("%s: unable to allocate ring buffer\n",
                    sc->sc_dev.dv_xname);
                return;
        }
        sc->sc_ebuf = sc->sc_rbuf + (plcom_rbuf_size << 1);

        tty_attach(tp);

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

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

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

                printf("%s: console\n", sc->sc_dev.dv_xname);
        }

#ifdef KGDB
        /*
         * Allow kgdb to "take over" this port.  If this is
         * the kgdb device, it has exclusive use.
         */
        if (iot == plcom_kgdb_iot && unit == plcom_kgdb_unit) {
                plcom_kgdb_attached = 1;

                SET(sc->sc_hwflags, PLCOM_HW_KGDB);
                printf("%s: kgdb\n", sc->sc_dev.dv_xname);
        }
#endif

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

#if NRND > 0 && defined(RND_COM)
        rnd_attach_source(&sc->rnd_source, sc->sc_dev.dv_xname,
                          RND_TYPE_TTY, 0);
#endif

        /* if there are no enable/disable functions, assume the device
           is always enabled */
        if (!sc->enable)
                sc->enabled = 1;

        plcom_config(sc);

        SET(sc->sc_hwflags, PLCOM_HW_DEV_OK);
}

void
plcom_config(struct plcom_softc *sc)
{
        bus_space_tag_t iot = sc->sc_iot;
        bus_space_handle_t ioh = sc->sc_ioh;

        /* Disable interrupts before configuring the device. */
        sc->sc_cr = 0;
        bus_space_write_1(iot, ioh, plcom_cr, sc->sc_cr);

        if (ISSET(sc->sc_hwflags, PLCOM_HW_CONSOLE|PLCOM_HW_KGDB))
                plcom_enable_debugport(sc);
}

int
plcom_detach(struct device *self, int flags)
{
        struct plcom_softc *sc = (struct plcom_softc *)self;
        int maj, mn;

        if (sc->sc_hwflags & (PLCOM_HW_CONSOLE|PLCOM_HW_KGDB))
                return EBUSY;

        if (sc->disable != NULL && sc->enabled != 0) {
                (*sc->disable)(sc);
                sc->enabled = 0;
        }

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

        /* Nuke the vnodes for any open instances. */
        mn = device_unit(self);
        vdevgone(maj, mn, mn, VCHR);

        mn |= PLCOMDIALOUT_MASK;
        vdevgone(maj, mn, mn, VCHR);

        /* Free the receive buffer. */
        free(sc->sc_rbuf, M_DEVBUF);

        /* Detach and free the tty. */
        tty_detach(sc->sc_tty);
        ttyfree(sc->sc_tty);

        /* Unhook the soft interrupt handler. */
        softint_disestablish(sc->sc_si);

#if NRND > 0 && defined(RND_COM)
        /* Unhook the entropy source. */
        rnd_detach_source(&sc->rnd_source);
#endif

        return 0;
}

int
plcom_activate(device_t self, enum devact act)
{
        struct plcom_softc *sc = device_private(self);

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

void
plcom_shutdown(struct plcom_softc *sc)
{
        struct tty *tp = sc->sc_tty;
        int s;

        s = splserial();
        PLCOM_LOCK(sc); 

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

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

        /* Turn off PPS capture on last close. */
        mutex_spin_enter(&timecounter_lock);
        sc->sc_ppsmask = 0;
        sc->ppsparam.mode = 0;
        mutex_spin_exit(&timecounter_lock);

        /*
         * 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)) {
                plcom_modem(sc, 0);
                PLCOM_UNLOCK(sc);
                splx(s);
                /* XXX tsleep will only timeout */
                (void) tsleep(sc, TTIPRI, ttclos, hz);
                s = splserial();
                PLCOM_LOCK(sc); 
        }

        /* Turn off interrupts. */
        if (ISSET(sc->sc_hwflags, PLCOM_HW_CONSOLE))
                /* interrupt on break */
                sc->sc_cr = CR_RIE | CR_RTIE | CR_UARTEN;
        else
                sc->sc_cr = 0;
        bus_space_write_1(sc->sc_iot, sc->sc_ioh, plcom_cr, sc->sc_cr);

        if (sc->disable) {
#ifdef DIAGNOSTIC
                if (!sc->enabled)
                        panic("plcom_shutdown: not enabled?");
#endif
                (*sc->disable)(sc);
                sc->enabled = 0;
        }
        PLCOM_UNLOCK(sc);
        splx(s);
}

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

        sc = device_lookup_private(&plcom_cd, PLCOMUNIT(dev));
        if (sc == NULL || !ISSET(sc->sc_hwflags, PLCOM_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, PLCOM_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();
                PLCOM_LOCK(sc);

                if (sc->enable) {
                        if ((*sc->enable)(sc)) {
                                PLCOM_UNLOCK(sc);
                                splx(s2);
                                splx(s);
                                printf("%s: device enable failed\n",
                                       sc->sc_dev.dv_xname);
                                return EIO;
                        }
                        sc->enabled = 1;
                        plcom_config(sc);
                }

                /* Turn on interrupts. */
                /* IER_ERXRDY | IER_ERLS | IER_EMSC;  */
                sc->sc_cr = CR_RIE | CR_RTIE | CR_MSIE | CR_UARTEN;
                bus_space_write_1(sc->sc_iot, sc->sc_ioh, plcom_cr, sc->sc_cr);

                /* Fetch the current modem control status, needed later. */
                sc->sc_msr = bus_space_read_1(sc->sc_iot, sc->sc_ioh, plcom_fr);

                /* Clear PPS capture state on first open. */

                mutex_spin_enter(&timecounter_lock);
                sc->sc_ppsmask = 0;
                sc->ppsparam.mode = 0;
                mutex_spin_exit(&timecounter_lock);

                PLCOM_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, PLCOM_HW_CONSOLE)) {
                        t.c_ospeed = plcomconsrate;
                        t.c_cflag = plcomconscflag;
                } 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 plcomparam() will do something. */
                tp->t_ospeed = 0;
                (void) plcomparam(tp, &t);
                tp->t_iflag = TTYDEF_IFLAG;
                tp->t_oflag = TTYDEF_OFLAG;
                tp->t_lflag = TTYDEF_LFLAG;
                ttychars(tp);
                ttsetwater(tp);

                s2 = splserial();
                PLCOM_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.
                 */
                plcom_modem(sc, 1);

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

#ifdef PLCOM_DEBUG
                if (plcom_debug)
                        plcomstatus(sc, "plcomopen  ");
#endif

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

        error = ttyopen(tp, PLCOMDIALOUT(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.
                 */
                plcom_shutdown(sc);
        }

        return error;
}
 
int
plcomclose(dev_t dev, int flag, int mode, struct lwp *l)
{
        struct plcom_softc *sc =
                device_lookup_private(&plcom_cd, PLCOMUNIT(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 (PLCOM_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.
                 */
                plcom_shutdown(sc);
        }

        return 0;
}
 
int
plcomread(dev_t dev, struct uio *uio, int flag)
{
        struct plcom_softc *sc =
                device_lookup_private(&plcom_cd, PLCOMUNIT(dev));
        struct tty *tp = sc->sc_tty;

        if (PLCOM_ISALIVE(sc) == 0)
                return EIO;
 
        return (*tp->t_linesw->l_read)(tp, uio, flag);
}
 
int
plcomwrite(dev_t dev, struct uio *uio, int flag)
{
        struct plcom_softc *sc =
                device_lookup_private(&plcom_cd, PLCOMUNIT(dev));
        struct tty *tp = sc->sc_tty;

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

int
plcompoll(dev_t dev, int events, struct lwp *l)
{
        struct plcom_softc *sc =
                device_lookup_private(&plcom_cd, PLCOMUNIT(dev));
        struct tty *tp = sc->sc_tty;

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

struct tty *
plcomtty(dev_t dev)
{
        struct plcom_softc *sc =
                device_lookup_private(&plcom_cd, PLCOMUNIT(dev));
        struct tty *tp = sc->sc_tty;

        return tp;
}

int
plcomioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
{
        struct plcom_softc *sc =
                device_lookup_private(&plcom_cd, PLCOMUNIT(dev));
        struct tty *tp = sc->sc_tty;
        int error;
        int s;

        if (PLCOM_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();
        PLCOM_LOCK(sc); 

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

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

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

        case TIOCCDTR:
                plcom_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_plcom(sc, cmd, *(int *)data);
                break;

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

        case PPS_IOC_CREATE:
                break;

        case PPS_IOC_DESTROY:
                break;

        case PPS_IOC_GETPARAMS: {
                pps_params_t *pp;
                pp = (pps_params_t *)data;
                mutex_spin_enter(&timecounter_lock);
                *pp = sc->ppsparam;
                mutex_spin_exit(&timecounter_lock);
                break;
        }

        case PPS_IOC_SETPARAMS: {
                pps_params_t *pp;
                int mode;
                pp = (pps_params_t *)data;
                mutex_spin_enter(&timecounter_lock);
                if (pp->mode & ~ppscap) {
                        error = EINVAL;
                        mutex_spin_exit(&timecounter_lock);
                        break;
                }
                sc->ppsparam = *pp;
                /* 
                 * Compute msr masks from user-specified timestamp state.
                 */
                mode = sc->ppsparam.mode;
#ifdef  PPS_SYNC
                if (mode & PPS_HARDPPSONASSERT) {
                        mode |= PPS_CAPTUREASSERT;
                        /* XXX revoke any previous HARDPPS source */
                }
                if (mode & PPS_HARDPPSONCLEAR) {
                        mode |= PPS_CAPTURECLEAR;
                        /* XXX revoke any previous HARDPPS source */
                }
#endif  /* PPS_SYNC */
                switch (mode & PPS_CAPTUREBOTH) {
                case 0:
                        sc->sc_ppsmask = 0;
                        break;
        
                case PPS_CAPTUREASSERT:
                        sc->sc_ppsmask = MSR_DCD;
                        sc->sc_ppsassert = MSR_DCD;
                        sc->sc_ppsclear = -1;
                        break;
        
                case PPS_CAPTURECLEAR:
                        sc->sc_ppsmask = MSR_DCD;
                        sc->sc_ppsassert = -1;
                        sc->sc_ppsclear = 0;
                        break;

                case PPS_CAPTUREBOTH:
                        sc->sc_ppsmask = MSR_DCD;
                        sc->sc_ppsassert = MSR_DCD;
                        sc->sc_ppsclear = 0;
                        break;

                default:
                        error = EINVAL;
                        break;
                }
                mutex_spin_exit(&timecounter_lock);
                break;
        }

        case PPS_IOC_GETCAP:
                *(int*)data = ppscap;
                break;

        case PPS_IOC_FETCH: {
                pps_info_t *pi;
                pi = (pps_info_t *)data;
                mutex_spin_enter(&timecounter_lock);
                *pi = sc->ppsinfo;
                mutex_spin_exit(&timecounter_lock);
                break;
        }

        case TIOCDCDTIMESTAMP:  /* XXX old, overloaded  API used by xntpd v3 */
                /*
                 * Some GPS clocks models use the falling rather than
                 * rising edge as the on-the-second signal. 
                 * The old API has no way to specify PPS polarity.
                 */
                mutex_spin_enter(&timecounter_lock);
                sc->sc_ppsmask = MSR_DCD;
#ifndef PPS_TRAILING_EDGE
                sc->sc_ppsassert = MSR_DCD;
                sc->sc_ppsclear = -1;
                TIMESPEC_TO_TIMEVAL((struct timeval *)data, 
                    &sc->ppsinfo.assert_timestamp);
#else
                sc->sc_ppsassert = -1
                sc->sc_ppsclear = 0;
                TIMESPEC_TO_TIMEVAL((struct timeval *)data, 
                    &sc->ppsinfo.clear_timestamp);
#endif
                mutex_spin_exit(&timecounter_lock);
                break;

        default:
                error = EPASSTHROUGH;
                break;
        }

        PLCOM_UNLOCK(sc);
        splx(s);

#ifdef PLCOM_DEBUG
        if (plcom_debug)
                plcomstatus(sc, "plcomioctl ");
#endif

        return error;
}

integrate void
plcom_schedrx(struct plcom_softc *sc)
{

        sc->sc_rx_ready = 1;

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

void
plcom_break(struct plcom_softc *sc, int onoff)
{

        if (onoff)
                SET(sc->sc_lcr, LCR_BRK);
        else
                CLR(sc->sc_lcr, LCR_BRK);

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

void
plcom_modem(struct plcom_softc *sc, int onoff)
{

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

        if (onoff)
                SET(sc->sc_mcr, sc->sc_mcr_dtr);
        else
                CLR(sc->sc_mcr, sc->sc_mcr_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
                        plcom_loadchannelregs(sc);
        }
}

void
tiocm_to_plcom(struct plcom_softc *sc, u_long how, int ttybits)
{
        u_char plcombits;

        plcombits = 0;
        if (ISSET(ttybits, TIOCM_DTR))
                SET(plcombits, MCR_DTR);
        if (ISSET(ttybits, TIOCM_RTS))
                SET(plcombits, MCR_RTS);
 
        switch (how) {
        case TIOCMBIC:
                CLR(sc->sc_mcr, plcombits);
                break;

        case TIOCMBIS:
                SET(sc->sc_mcr, plcombits);
                break;

        case TIOCMSET:
                CLR(sc->sc_mcr, MCR_DTR | MCR_RTS);
                SET(sc->sc_mcr, plcombits);
                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
                        plcom_loadchannelregs(sc);
        }
}

int
plcom_to_tiocm(struct plcom_softc *sc)
{
        u_char plcombits;
        int ttybits = 0;

        plcombits = sc->sc_mcr;
        if (ISSET(plcombits, MCR_DTR))
                SET(ttybits, TIOCM_DTR);
        if (ISSET(plcombits, MCR_RTS))
                SET(ttybits, TIOCM_RTS);

        plcombits = sc->sc_msr;
        if (ISSET(plcombits, MSR_DCD))
                SET(ttybits, TIOCM_CD);
        if (ISSET(plcombits, MSR_CTS))
                SET(ttybits, TIOCM_CTS);
        if (ISSET(plcombits, MSR_DSR))
                SET(ttybits, TIOCM_DSR);

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

        return ttybits;
}

static u_char
cflag2lcr(tcflag_t cflag)
{
        u_char lcr = 0;

        switch (ISSET(cflag, CSIZE)) {
        case CS5:
                SET(lcr, LCR_5BITS);
                break;
        case CS6:
                SET(lcr, LCR_6BITS);
                break;
        case CS7:
                SET(lcr, LCR_7BITS);
                break;
        case CS8:
                SET(lcr, LCR_8BITS);
                break;
        }
        if (ISSET(cflag, PARENB)) {
                SET(lcr, LCR_PEN);
                if (!ISSET(cflag, PARODD))
                        SET(lcr, LCR_EPS);
        }
        if (ISSET(cflag, CSTOPB))
                SET(lcr, LCR_STP2);

        return lcr;
}

int
plcomparam(struct tty *tp, struct termios *t)
{
        struct plcom_softc *sc =
                device_lookup_private(&plcom_cd, PLCOMUNIT(tp->t_dev));
        int ospeed;
        u_char lcr;
        int s;

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

        ospeed = plcomspeed(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, PLCOM_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 = ISSET(sc->sc_lcr, LCR_BRK) | cflag2lcr(t->c_cflag);

        s = splserial();
        PLCOM_LOCK(sc); 

        sc->sc_lcr = lcr;

        /*
         * PL010 has a fixed-length FIFO trigger point.
         */
        if (ISSET(sc->sc_hwflags, PLCOM_HW_FIFO))
                sc->sc_fifo = 1;
        else
                sc->sc_fifo = 0;

        if (sc->sc_fifo)
                SET(sc->sc_lcr, LCR_FEN);

        /*
         * 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 = MSR_DCD;
        /*
         * Set the flow control pins depending on the current flow control
         * mode.
         */
        if (ISSET(t->c_cflag, CRTSCTS)) {
                sc->sc_mcr_dtr = MCR_DTR;
                sc->sc_mcr_rts = MCR_RTS;
                sc->sc_msr_cts = MSR_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 = MCR_DTR;
                sc->sc_msr_cts = MSR_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 = MCR_DTR | MCR_RTS;
                sc->sc_mcr_rts = 0;
                sc->sc_msr_cts = 0;
                if (ISSET(sc->sc_mcr, MCR_DTR))
                        SET(sc->sc_mcr, MCR_RTS);
                else
                        CLR(sc->sc_mcr, MCR_RTS);
        }
        sc->sc_msr_mask = sc->sc_msr_cts | sc->sc_msr_dcd;

#if 0
        if (ospeed == 0)
                CLR(sc->sc_mcr, sc->sc_mcr_dtr);
        else
                SET(sc->sc_mcr, sc->sc_mcr_dtr);
#endif

        sc->sc_dlbl = ospeed;
        sc->sc_dlbh = ospeed >> 8;

        /* 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
                        plcom_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);
                        plcom_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);
                        plcom_hwiflow(sc);
                }
        } else {
                sc->sc_r_hiwat = plcom_rbuf_hiwat;
                sc->sc_r_lowat = plcom_rbuf_lowat;
        }

        PLCOM_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_msr, MSR_DCD));

#ifdef PLCOM_DEBUG
        if (plcom_debug)
                plcomstatus(sc, "plcomparam ");
#endif

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

        return 0;
}

void
plcom_iflush(struct plcom_softc *sc)
{
        bus_space_tag_t iot = sc->sc_iot;
        bus_space_handle_t ioh = sc->sc_ioh;
#ifdef DIAGNOSTIC
        int reg;
#endif
        int timo;

#ifdef DIAGNOSTIC
        reg = 0xffff;
#endif
        timo = 50000;
        /* flush any pending I/O */
        while (! ISSET(bus_space_read_1(iot, ioh, plcom_fr), FR_RXFE)
            && --timo)
#ifdef DIAGNOSTIC
                reg =
#else
                    (void)
#endif
                    bus_space_read_1(iot, ioh, plcom_dr);
#ifdef DIAGNOSTIC
        if (!timo)
                printf("%s: plcom_iflush timeout %02x\n", sc->sc_dev.dv_xname,
                       reg);
#endif
}

void
plcom_loadchannelregs(struct plcom_softc *sc)
{
        bus_space_tag_t iot = sc->sc_iot;
        bus_space_handle_t ioh = sc->sc_ioh;

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

        bus_space_write_1(iot, ioh, plcom_cr, 0);

        bus_space_write_1(iot, ioh, plcom_dlbl, sc->sc_dlbl);
        bus_space_write_1(iot, ioh, plcom_dlbh, sc->sc_dlbh);
        bus_space_write_1(iot, ioh, plcom_lcr, sc->sc_lcr);
        /* XXX device_unit() abuse */
        sc->sc_set_mcr(sc->sc_set_mcr_arg, device_unit(&sc->sc_dev),
            sc->sc_mcr_active = sc->sc_mcr);

        bus_space_write_1(iot, ioh, plcom_cr, sc->sc_cr);
}

int
plcomhwiflow(struct tty *tp, int block)
{
        struct plcom_softc *sc =
                device_lookup_private(&plcom_cd, PLCOMUNIT(tp->t_dev));
        int s;

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

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

        s = splserial();
        PLCOM_LOCK(sc);
        
        if (block) {
                if (!ISSET(sc->sc_rx_flags, RX_TTY_BLOCKED)) {
                        SET(sc->sc_rx_flags, RX_TTY_BLOCKED);
                        plcom_hwiflow(sc);
                }
        } else {
                if (ISSET(sc->sc_rx_flags, RX_TTY_OVERFLOWED)) {
                        CLR(sc->sc_rx_flags, RX_TTY_OVERFLOWED);
                        plcom_schedrx(sc);
                }
                if (ISSET(sc->sc_rx_flags, RX_TTY_BLOCKED)) {
                        CLR(sc->sc_rx_flags, RX_TTY_BLOCKED);
                        plcom_hwiflow(sc);
                }
        }

        PLCOM_UNLOCK(sc);
        splx(s);
        return 1;
}
        
/*
 * (un)block input via hw flowcontrol
 */
void
plcom_hwiflow(struct plcom_softc *sc)
{
        if (sc->sc_mcr_rts == 0)
                return;

        if (ISSET(sc->sc_rx_flags, RX_ANY_BLOCK)) {
                CLR(sc->sc_mcr, sc->sc_mcr_rts);
                CLR(sc->sc_mcr_active, sc->sc_mcr_rts);
        } else {
                SET(sc->sc_mcr, sc->sc_mcr_rts);
                SET(sc->sc_mcr_active, sc->sc_mcr_rts);
        }
        /* XXX device_unit() abuse */
        sc->sc_set_mcr(sc->sc_set_mcr_arg, device_unit(&sc->sc_dev),
            sc->sc_mcr_active);
}


void
plcomstart(struct tty *tp)
{
        struct plcom_softc *sc =
                device_lookup_private(&plcom_cd, PLCOMUNIT(tp->t_dev));
        bus_space_tag_t iot = sc->sc_iot;
        bus_space_handle_t ioh = sc->sc_ioh;
        int s;

        if (PLCOM_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();
                PLCOM_LOCK(sc);

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

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

        /* Enable transmit completion interrupts if necessary. */
        if (!ISSET(sc->sc_cr, CR_TIE)) {
                SET(sc->sc_cr, CR_TIE);
                bus_space_write_1(iot, ioh, plcom_cr, sc->sc_cr);
        }

        /* Output the first chunk of the contiguous buffer. */
        {
                int n;

                n = sc->sc_tbc;
                if (n > sc->sc_fifolen)
                        n = sc->sc_fifolen;
                bus_space_write_multi_1(iot, ioh, plcom_dr, sc->sc_tba, n);
                sc->sc_tbc -= n;
                sc->sc_tba += n;
        }
        PLCOM_UNLOCK(sc);
out:
        splx(s);
        return;
}

/*
 * Stop output on a line.
 */
void
plcomstop(struct tty *tp, int flag)
{
        struct plcom_softc *sc =
                device_lookup_private(&plcom_cd, PLCOMUNIT(tp->t_dev));
        int s;

        s = splserial();
        PLCOM_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);
        }
        PLCOM_UNLOCK(sc);       
        splx(s);
}

void
plcomdiag(void *arg)
{
        struct plcom_softc *sc = arg;
        int overflows, floods;
        int s;

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

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

integrate void
plcom_rxsoft(struct plcom_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 = plcom_rbuf_size - sc->sc_rbavail;

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

        while (cc) {
                code = get[0];
                rsr = get[1];
                if (ISSET(rsr, RSR_OE | RSR_BE | RSR_FE | RSR_PE)) {
                        if (ISSET(rsr, RSR_OE)) {
                                sc->sc_overflows++;
                                if (sc->sc_errors++ == 0)
                                        callout_reset(&sc->sc_diag_callout,
                                            60 * hz, plcomdiag, sc);
                        }
                        if (ISSET(rsr, RSR_BE | RSR_FE))
                                SET(code, TTY_FE);
                        if (ISSET(rsr, RSR_PE))
                                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 -= plcom_rbuf_size << 1;
                                cc = 0;
                        } else {
                                /*
                                 * Don't schedule any more receive processing
                                 * until the line discipline tells us there's
                                 * space available (through plcomhwiflow()).
                                 * 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();
                PLCOM_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);
                                SET(sc->sc_cr, CR_RIE | CR_RTIE);
                                bus_space_write_1(sc->sc_iot, sc->sc_ioh, plcom_cr, sc->sc_cr);
                        }
                        if (ISSET(sc->sc_rx_flags, RX_IBUF_BLOCKED)) {
                                CLR(sc->sc_rx_flags, RX_IBUF_BLOCKED);
                                plcom_hwiflow(sc);
                        }
                }
                PLCOM_UNLOCK(sc);
                splx(s);
        }
}

integrate void
plcom_txsoft(struct plcom_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
plcom_stsoft(struct plcom_softc *sc, struct tty *tp)
{
        u_char msr, delta;
        int s;

        s = splserial();
        PLCOM_LOCK(sc);
        msr = sc->sc_msr;
        delta = sc->sc_msr_delta;
        sc->sc_msr_delta = 0;
        PLCOM_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, MSR_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;
                }
        }

#ifdef PLCOM_DEBUG
        if (plcom_debug)
                plcomstatus(sc, "plcom_stsoft");
#endif
}

void
plcomsoft(void *arg)
{
        struct plcom_softc *sc = arg;
        struct tty *tp;

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

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

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

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

int
plcomintr(void *arg)
{
        struct plcom_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;
        u_char rsr, iir;

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

        PLCOM_LOCK(sc);
        iir = bus_space_read_1(iot, ioh, plcom_iir);
        if (! ISSET(iir, IIR_IMASK)) {
                PLCOM_UNLOCK(sc);
                return 0;
        }

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

        do {
                u_char  msr, delta, fr;

                fr = bus_space_read_1(iot, ioh, plcom_fr);

                if (!ISSET(fr, FR_RXFE) &&
                    !ISSET(sc->sc_rx_flags, RX_IBUF_OVERFLOWED)) {
                        while (cc > 0) {
                                int cn_trapped = 0;
                                put[0] = bus_space_read_1(iot, ioh,
                                    plcom_dr);
                                rsr = bus_space_read_1(iot, ioh, plcom_rsr);
                                /* Clear any error status.  */
                                if (ISSET(rsr,
                                    (RSR_BE | RSR_OE | RSR_PE | RSR_FE)))
                                        bus_space_write_1(iot, ioh, plcom_ecr,
                                            0);
                                if (ISSET(rsr, RSR_BE)) {
                                        cn_trapped = 0;
                                        cn_check_magic(sc->sc_tty->t_dev,
                                            CNC_BREAK, plcom_cnm_state);
                                        if (cn_trapped)
                                                continue;
#if defined(KGDB)
                                        if (ISSET(sc->sc_hwflags,
                                            PLCOM_HW_KGDB)) {
                                                kgdb_connect(1);
                                                continue;
                                        }
#endif
                                }

                                put[1] = rsr;
                                cn_trapped = 0;
                                cn_check_magic(sc->sc_tty->t_dev,
                                               put[0], plcom_cnm_state);
                                if (cn_trapped) {
                                        fr = bus_space_read_1(iot, ioh,
                                            plcom_fr);
                                        if (ISSET(fr, FR_RXFE))
                                                break;

                                        continue;
                                }
                                put += 2;
                                if (put >= end)
                                        put = sc->sc_rbuf;
                                cc--;

                                fr = bus_space_read_1(iot, ioh, plcom_fr);
                                if (ISSET(fr, FR_RXFE))
                                        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);
                                plcom_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);
                                CLR(sc->sc_cr, CR_RIE | CR_RTIE);
                                bus_space_write_1(iot, ioh, plcom_cr,
                                    sc->sc_cr);
                        }
                } else {
                        if (ISSET(iir, IIR_RIS)) {
                                bus_space_write_1(iot, ioh, plcom_cr, 0);
                                delay(10);
                                bus_space_write_1(iot, ioh, plcom_cr,
                                    sc->sc_cr);
                                continue;
                        }
                }

                msr = bus_space_read_1(iot, ioh, plcom_fr);
                delta = msr ^ sc->sc_msr;
                sc->sc_msr = msr;
                /* Clear any pending modem status interrupt.  */
                if (iir & IIR_MIS)
                        bus_space_write_1(iot, ioh, plcom_icr, 0);
                /*
                 * 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;
                        mutex_spin_enter(&timecounter_lock);
                        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;
                        }
                        mutex_spin_exit(&timecounter_lock);
                }

                /*
                 * 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(~msr, sc->sc_msr_mask)) {
                                sc->sc_tbc = 0;
                                sc->sc_heldtbc = 0;
#ifdef PLCOM_DEBUG
                                if (plcom_debug)
                                        plcomstatus(sc, "plcomintr  ");
#endif
                        }

                        sc->sc_st_check = 1;
                }

                /* 
                 * Done handling any receive interrupts. See if data
                 * can be * transmitted as well. Schedule tx done
                 * event if no data left * and tty was marked busy.
                 */
                if (ISSET(iir, IIR_TIS)) {
                        /*
                         * If we've delayed a parameter change, do it
                         * now, and restart * output.
                         */
                        if (sc->sc_heldchange) {
                                plcom_loadchannelregs(sc);
                                sc->sc_heldchange = 0;
                                sc->sc_tbc = sc->sc_heldtbc;
                                sc->sc_heldtbc = 0;
                        }

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

                                n = sc->sc_tbc;
                                if (n > sc->sc_fifolen)
                                        n = sc->sc_fifolen;
                                bus_space_write_multi_1(iot, ioh, plcom_dr,
                                    sc->sc_tba, n);
                                sc->sc_tbc -= n;
                                sc->sc_tba += n;
                        } else {
                                /*
                                 * Disable transmit plcompletion
                                 * interrupts if necessary.
                                 */
                                if (ISSET(sc->sc_cr, CR_TIE)) {
                                        CLR(sc->sc_cr, CR_TIE);
                                        bus_space_write_1(iot, ioh, plcom_cr,
                                            sc->sc_cr);
                                }
                                if (sc->sc_tx_busy) {
                                        sc->sc_tx_busy = 0;
                                        sc->sc_tx_done = 1;
                                }
                        }
                }
        } while (ISSET((iir = bus_space_read_1(iot, ioh, plcom_iir)),
            IIR_IMASK));

        PLCOM_UNLOCK(sc);

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

#if NRND > 0 && defined(RND_COM)
        rnd_add_uint32(&sc->rnd_source, iir | rsr);
#endif

        return 1;
}

/*
 * The following functions are polled getc and putc routines, shared
 * by the console and kgdb glue.
 * 
 * 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 plcom_readahead[MAX_READAHEAD];
static int plcom_readaheadcount = 0;

int
plcom_common_getc(dev_t dev, bus_space_tag_t iot, bus_space_handle_t ioh)
{
        int s = splserial();
        u_char stat, c;

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

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

        /* block until a character becomes available */
        while (ISSET(stat = bus_space_read_1(iot, ioh, plcom_fr), FR_RXFE))
                ;

        c = bus_space_read_1(iot, ioh, plcom_dr);
        stat = bus_space_read_1(iot, ioh, plcom_iir);
        {
                int cn_trapped = 0; /* unused */
#ifdef DDB
                extern int db_active;
                if (!db_active)
#endif
                        cn_check_magic(dev, c, plcom_cnm_state);
        }
        splx(s);
        return c;
}

void
plcom_common_putc(dev_t dev, bus_space_tag_t iot, bus_space_handle_t ioh,
    int c)
{
        int s = splserial();
        int timo;

        int cin, stat;
        if (plcom_readaheadcount < MAX_READAHEAD 
             && !ISSET(stat = bus_space_read_1(iot, ioh, plcom_fr), FR_RXFE)) {
                int cn_trapped = 0;
                cin = bus_space_read_1(iot, ioh, plcom_dr);
                stat = bus_space_read_1(iot, ioh, plcom_iir);
                cn_check_magic(dev, cin, plcom_cnm_state);
                plcom_readahead[plcom_readaheadcount++] = cin;
        }

        /* wait for any pending transmission to finish */
        timo = 150000;
        while (!ISSET(bus_space_read_1(iot, ioh, plcom_fr), FR_TXFE) && --timo)
                continue;

        bus_space_write_1(iot, ioh, plcom_dr, c);
        PLCOM_BARRIER(iot, ioh, BR | BW);

        /* wait for this transmission to complete */
        timo = 1500000;
        while (!ISSET(bus_space_read_1(iot, ioh, plcom_fr), FR_TXFE) && --timo)
                continue;

        splx(s);
}

/*
 * Initialize UART for use as console or KGDB line.
 */
int
plcominit(bus_space_tag_t iot, bus_addr_t iobase, int rate, int frequency,
    tcflag_t cflag, bus_space_handle_t *iohp)
{
        bus_space_handle_t ioh;

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

        rate = plcomspeed(rate, frequency);
        bus_space_write_1(iot, ioh, plcom_cr, 0);
        bus_space_write_1(iot, ioh, plcom_dlbl, rate);
        bus_space_write_1(iot, ioh, plcom_dlbh, rate >> 8);
        bus_space_write_1(iot, ioh, plcom_lcr, cflag2lcr(cflag) | LCR_FEN);
        bus_space_write_1(iot, ioh, plcom_cr, CR_UARTEN);

#if 0
        /* Ought to do something like this, but we have no sc to
           dereference. */
        /* XXX device_unit() abuse */
        sc->sc_set_mcr(sc->sc_set_mcr_arg, device_unit(&sc->sc_dev),
            MCR_DTR | MCR_RTS);
#endif

        *iohp = ioh;
        return 0;
}

/*
 * Following are all routines needed for PLCOM to act as console
 */
struct consdev plcomcons = {
        NULL, NULL, plcomcngetc, plcomcnputc, plcomcnpollc, NULL,
        NULL, NULL, NODEV, CN_NORMAL
};


int
plcomcnattach(bus_space_tag_t iot, bus_addr_t iobase, int rate, int frequency,
    tcflag_t cflag, int unit)
{
        int res;

        res = plcominit(iot, iobase, rate, frequency, cflag, &plcomconsioh);
        if (res)
                return res;

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

        plcomconstag = iot;
        plcomconsunit = unit;
        plcomconsrate = rate;
        plcomconscflag = cflag;

        return 0;
}

void
plcomcndetach(void)
{
        bus_space_unmap(plcomconstag, plcomconsioh, PLCOM_UART_SIZE);
        plcomconstag = NULL;

        cn_tab = NULL;
}

int
plcomcngetc(dev_t dev)
{
        return plcom_common_getc(dev, plcomconstag, plcomconsioh);
}

/*
 * Console kernel output character routine.
 */
void
plcomcnputc(dev_t dev, int c)
{
        plcom_common_putc(dev, plcomconstag, plcomconsioh, c);
}

void
plcomcnpollc(dev_t dev, int on)
{

}

#ifdef KGDB
int
plcom_kgdb_attach(bus_space_tag_t iot, bus_addr_t iobase, int rate,
   int frequency, tcflag_t cflag, int unit)
{
        int res;

        if (iot == plcomconstag && iobase == plcomconsunit)
                return EBUSY; /* cannot share with console */

        res = plcominit(iot, iobase, rate, frequency, cflag, &plcom_kgdb_ioh);
        if (res)
                return res;

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

        plcom_kgdb_iot = iot;
        plcom_kgdb_unit = unit;

        return 0;
}

/* ARGSUSED */
int
plcom_kgdb_getc(void *arg)
{
        return plcom_common_getc(NODEV, plcom_kgdb_iot, plcom_kgdb_ioh);
}

/* ARGSUSED */
void
plcom_kgdb_putc(void *arg, int c)
{
        plcom_common_putc(NODEV, plcom_kgdb_iot, plcom_kgdb_ioh, c);
}
#endif /* KGDB */

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

        if (!plcomconsattached &&
            iot == plcomconstag && unit == plcomconsunit)
                help = plcomconsioh;
#ifdef KGDB
        else if (!plcom_kgdb_attached &&
            iot == plcom_kgdb_iot && unit == plcom_kgdb_unit)
                help = plcom_kgdb_ioh;
#endif
        else
                return 0;

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