/* $NetBSD: imxuart.c,v 1.30 2022/10/26 23:38:06 riastradh Exp $ */

/*
 * Copyright (c) 2009, 2010  Genetec Corporation.  All rights reserved.
 * Written by Hiroyuki Bessho for Genetec Corporation.
 *
 * 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 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 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.
 *
 */

/*
 * derived from sys/dev/ic/com.c
 */

/*-
 * Copyright (c) 1998, 1999, 2004, 2008 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
 */

/*
 * driver for UART in i.MX SoC.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: imxuart.c,v 1.30 2022/10/26 23:38:06 riastradh Exp $");

#include "opt_imxuart.h"
#include "opt_ddb.h"
#include "opt_ddbparam.h"
#include "opt_kgdb.h"
#include "opt_lockdebug.h"
#include "opt_multiprocessor.h"
#include "opt_ntp.h"
#include "opt_imxuart.h"

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

#ifndef IMXUART_TOLERANCE
#define IMXUART_TOLERANCE       30      /* baud rate tolerance, in 0.1% units */
#endif

#ifndef IMXUART_FREQDIV
#define IMXUART_FREQDIV         2       /* XXX */
#endif

#ifndef IMXUART_FREQ
#define IMXUART_FREQ    (56900000)
#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/poll.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/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 <ddb/db_active.h>

#include <arm/imx/imxuartreg.h>
#include <arm/imx/imxuartvar.h>
#include <dev/cons.h>

#ifndef IMXUART_RING_SIZE
#define IMXUART_RING_SIZE       2048
#endif

int     imxuspeed(long, struct imxuart_baudrate_ratio *);
int     imxuparam(struct tty *, struct termios *);
void    imxustart(struct tty *);
int     imxuhwiflow(struct tty *, int);

void    imxuart_shutdown(struct imxuart_softc *);
void    imxuart_loadchannelregs(struct imxuart_softc *);
void    imxuart_hwiflow(struct imxuart_softc *);
void    imxuart_break(struct imxuart_softc *, bool);
void    imxuart_modem(struct imxuart_softc *, int);
void    tiocm_to_imxu(struct imxuart_softc *, u_long, int);
int     imxuart_to_tiocm(struct imxuart_softc *);
void    imxuart_iflush(struct imxuart_softc *);
int     imxuintr(void *);

int     imxuart_common_getc(dev_t, struct imxuart_regs *);
void    imxuart_common_putc(dev_t, struct imxuart_regs *, int);


int     imxuart_init(struct imxuart_regs *, int, tcflag_t, int);

int     imxucngetc(dev_t);
void    imxucnputc(dev_t, int);
void    imxucnpollc(dev_t, int);

static void imxuintr_read(struct imxuart_softc *);
static void imxuintr_send(struct imxuart_softc *);

static void imxuart_enable_debugport(struct imxuart_softc *);
static void imxuart_disable_all_interrupts(struct imxuart_softc *);
static void imxuart_control_rxint(struct imxuart_softc *, bool);
static void imxuart_control_txint(struct imxuart_softc *, bool);
static u_int imxuart_txfifo_space(struct imxuart_softc *sc);

static  uint32_t        cflag_to_ucr2(tcflag_t, uint32_t);

#define integrate       static inline
void    imxusoft(void *);
integrate void imxuart_rxsoft(struct imxuart_softc *, struct tty *);
integrate void imxuart_txsoft(struct imxuart_softc *, struct tty *);
integrate void imxuart_stsoft(struct imxuart_softc *, struct tty *);
integrate void imxuart_schedrx(struct imxuart_softc *);
void    imxudiag(void *);
static void imxuart_load_speed(struct imxuart_softc *);
static void imxuart_load_params(struct imxuart_softc *);
integrate void imxuart_load_pendings(struct imxuart_softc *);


extern struct cfdriver imxuart_cd;

dev_type_open(imxuopen);
dev_type_close(imxuclose);
dev_type_read(imxuread);
dev_type_write(imxuwrite);
dev_type_ioctl(imxuioctl);
dev_type_stop(imxustop);
dev_type_tty(imxutty);
dev_type_poll(imxupoll);

const struct cdevsw imxcom_cdevsw = {
        .d_open = imxuopen,
        .d_close = imxuclose,
        .d_read = imxuread,
        .d_write = imxuwrite,
        .d_ioctl = imxuioctl,
        .d_stop = imxustop,
        .d_tty = imxutty,
        .d_poll = imxupoll,
        .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 imxuart_rbuf_size = IMXUART_RING_SIZE;

/* Stop input when 3/4 of the ring is full; restart when only 1/4 is full. */
u_int imxuart_rbuf_hiwat = (IMXUART_RING_SIZE * 1) / 4;
u_int imxuart_rbuf_lowat = (IMXUART_RING_SIZE * 3) / 4;

static struct imxuart_regs imxuconsregs;
static int imxuconsattached;
static int imxuconsrate;
static tcflag_t imxuconscflag;
static struct cnm_state imxuart_cnm_state;

u_int imxuart_freq = IMXUART_FREQ;
u_int imxuart_freqdiv = IMXUART_FREQDIV;

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

static struct imxuart_regs imxu_kgdb_regs;
static int imxu_kgdb_attached;

int     imxuart_kgdb_getc(void *);
void    imxuart_kgdb_putc(void *, int);
#endif /* KGDB */

#define IMXUART_DIALOUT_MASK    TTDIALOUT_MASK

#define IMXUART_UNIT(x)         TTUNIT(x)
#define IMXUART_DIALOUT(x)      TTDIALOUT(x)

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

#define BR      BUS_SPACE_BARRIER_READ
#define BW      BUS_SPACE_BARRIER_WRITE
#define IMXUART_BARRIER(r, f) \
        bus_space_barrier((r)->ur_iot, (r)->ur_ioh, 0, IMX_UART_SIZE, (f))


void
imxuart_attach_common(device_t parent, device_t self,
    bus_space_tag_t iot, paddr_t iobase, size_t size, int intr, int flags)
{
        struct imxuart_softc *sc = device_private(self);
        struct imxuart_regs *regsp = &sc->sc_regs;
        bus_space_handle_t ioh;

        aprint_naive("\n");
        aprint_normal("\n");

        sc->sc_dev = self;

        if (size <= 0)
                size = IMX_UART_SIZE;

        sc->sc_intr = intr;
        regsp->ur_iot = iot;
        regsp->ur_iobase = iobase;

        if (bus_space_map(iot, regsp->ur_iobase, size, 0, &ioh)) {
                return;
        }
        regsp->ur_ioh = ioh;

        sc->sc_ih = intr_establish(sc->sc_intr, IPL_SERIAL, IST_LEVEL,
            imxuintr, sc);
        if (sc->sc_ih == NULL) {
                aprint_error_dev(sc->sc_dev, "intr_establish failed\n");
                return;
        }

        imxuart_attach_subr(sc);
}

void
imxuart_attach_subr(struct imxuart_softc *sc)
{
        struct imxuart_regs *regsp = &sc->sc_regs;
        bus_space_tag_t iot = regsp->ur_iot;
        bus_space_handle_t ioh = regsp->ur_ioh;
        struct tty *tp;

        callout_init(&sc->sc_diag_callout, 0);
        mutex_init(&sc->sc_lock, MUTEX_DEFAULT, IPL_HIGH);

        if (regsp->ur_iobase != imxuconsregs.ur_iobase)
                imxuart_init(&sc->sc_regs, TTYDEF_SPEED, TTYDEF_CFLAG, false);

        bus_space_read_region_4(iot, ioh, IMX_UCR1, sc->sc_ucr, 4);
        sc->sc_ucr2_d = sc->sc_ucr2;

        /* Disable interrupts before configuring the device. */
        imxuart_disable_all_interrupts(sc);

        if (regsp->ur_iobase == imxuconsregs.ur_iobase) {
                imxuconsattached = 1;

                /* Make sure the console is always "hardwired". */
#if 0
                delay(10000);                   /* wait for output to finish */
#endif
                SET(sc->sc_hwflags, IMXUART_HW_CONSOLE);
                SET(sc->sc_swflags, TIOCFLAG_SOFTCAR);
        }


        tp = tty_alloc();
        tp->t_oproc = imxustart;
        tp->t_param = imxuparam;
        tp->t_hwiflow = imxuhwiflow;

        sc->sc_tty = tp;
        sc->sc_rbuf = kmem_alloc(sizeof (*sc->sc_rbuf) * imxuart_rbuf_size,
            KM_SLEEP);
        sc->sc_rbuf_size = imxuart_rbuf_size;
        sc->sc_rbuf_in = sc->sc_rbuf_out = 0;
        sc->sc_txfifo_len = 32;
        sc->sc_txfifo_thresh = 16;      /* when USR1.TRDY, fifo has space
                                         * for this many characters */

        tty_attach(tp);

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

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

                if (maj != NODEVMAJOR) {
                        tp->t_dev = cn_tab->cn_dev = makedev(maj,
                            device_unit(sc->sc_dev));

                        aprint_normal_dev(sc->sc_dev, "console\n");
                }
        }

#ifdef KGDB
        /*
         * Allow kgdb to "take over" this port.  If this is
         * not the console and is the kgdb device, it has
         * exclusive use.  If it's the console _and_ the
         * kgdb device, it doesn't.
         */
        if (regsp->ur_iobase == imxu_kgdb_regs.ur_iobase) {
                if (!ISSET(sc->sc_hwflags, IMXUART_HW_CONSOLE)) {
                        imxu_kgdb_attached = 1;

                        SET(sc->sc_hwflags, IMXUART_HW_KGDB);
                }
                aprint_normal_dev(sc->sc_dev, "kgdb\n");
        }
#endif

        sc->sc_si = softint_establish(SOFTINT_SERIAL, imxusoft, 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 (!sc->enable)
                sc->enabled = 1;

        imxuart_enable_debugport(sc);

        SET(sc->sc_hwflags, IMXUART_HW_DEV_OK);

        //shutdownhook_establish(imxuart_shutdownhook, sc);


#if 0
        {
                uint32_t reg;
                reg = bus_space_read_4(iot, ioh, IMX_UCR1);
                reg |= IMX_UCR1_TXDMAEN | IMX_UCR1_RXDMAEN;
                bus_space_write_4(iot, ioh, IMX_UCR1, reg);
        }
#endif
}

/*
 * baudrate = RefFreq / (16 * (UMBR + 1)/(UBIR + 1))
 *
 * (UBIR + 1) / (UBMR + 1) = (16 * BaurdRate) / RefFreq
 */

static long
gcd(long m, long n)
{

        if (m < n)
                return gcd(n, m);

        if (n <= 0)
                return m;
        return gcd(n, m % n);
}

int
imxuspeed(long speed, struct imxuart_baudrate_ratio *ratio)
{
#define divrnd(n, q)    (((n)*2/(q)+1)/2)       /* divide and round off */
        long b = 16 * speed;
        long f = imxuart_freq / imxuart_freqdiv;
        long d;
        int err = 0;

        /* reduce b/f */
        while ((f > (1<<16) || b > (1<<16)) && (d = gcd(f, b)) > 1) {
                f /= d;
                b /= d;
        }


        while (f > (1<<16) || b > (1<<16)) {
                f /= 2;
                b /= 2;
        }
        if (f <= 0 || b <= 0)
                return -1;

#ifdef  DIAGNOSTIC
        err = divrnd(((uint64_t)imxuart_freq) * 1000 / imxuart_freqdiv,
                     (uint64_t)speed * 16 * f / b) - 1000;
        if (err < 0)
                err = -err;
#endif

        ratio->numerator = b-1;
        ratio->modulator = f-1;

        if (err > IMXUART_TOLERANCE)
                return -1;

        return 0;
#undef  divrnd
}

#ifdef IMXUART_DEBUG
int     imxuart_debug = 0;

void imxustatus(struct imxuart_softc *, const char *);
void
imxustatus(struct imxuart_softc *sc, const char *str)
{
        struct tty *tp = sc->sc_tty;

        aprint_normal_dev(sc->sc_dev,
            "%s %cclocal  %cdcd %cts_carr_on %cdtr %ctx_stopped\n",
            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 ? '+' : '-');

        aprint_normal_dev(sc->sc_dev,
            "%s %ccrtscts %ccts %cts_ttstop  %crts rx_flags=0x%x\n",
            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

#if 0
int
imxuart_detach(device_t self, int flags)
{
        struct imxuart_softc *sc = device_private(self);
        int maj, mn;

        if (ISSET(sc->sc_hwflags, IMXUART_HW_CONSOLE))
                return EBUSY;

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

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

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

        if (sc->sc_rbuf == NULL) {
                /*
                 * Ring buffer allocation failed in the imxuart_attach_subr,
                 * only the tty is allocated, and nothing else.
                 */
                tty_free(sc->sc_tty);
                return 0;
        }

        /* Free the receive buffer. */
        kmem_free(sc->sc_rbuf, sizeof(*sc->sc_rbuf) * sc->sc_rbuf_size);

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

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

#ifdef RND_COM
        /* Unhook the entropy source. */
        rnd_detach_source(&sc->rnd_source);
#endif
        callout_destroy(&sc->sc_diag_callout);

        /* Destroy the lock. */
        mutex_destroy(&sc->sc_lock);

        return (0);
}
#endif

#ifdef notyet
int
imxuart_activate(device_t self, enum devact act)
{
        struct imxuart_softc *sc = device_private(self);
        int rv = 0;

        switch (act) {
        case DVACT_ACTIVATE:
                rv = EOPNOTSUPP;
                break;

        case DVACT_DEACTIVATE:
                if (sc->sc_hwflags & (IMXUART_HW_CONSOLE|IMXUART_HW_KGDB)) {
                        rv = EBUSY;
                        break;
                }

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

        return (rv);
}
#endif

void
imxuart_shutdown(struct imxuart_softc *sc)
{
        struct tty *tp = sc->sc_tty;

        mutex_spin_enter(&sc->sc_lock);

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

        /* Clear any break condition set with TIOCSBRK. */
        imxuart_break(sc, false);

        /*
         * 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)) {
                imxuart_modem(sc, 0);
                mutex_spin_exit(&sc->sc_lock);
                /* XXX will only timeout */
                (void) kpause(ttclos, false, hz, NULL);
                mutex_spin_enter(&sc->sc_lock);
        }

        /* Turn off interrupts. */
        imxuart_disable_all_interrupts(sc);
        /* re-enable recv interrupt for console or kgdb port */
        imxuart_enable_debugport(sc);

        mutex_spin_exit(&sc->sc_lock);

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

int
imxuopen(dev_t dev, int flag, int mode, struct lwp *l)
{
        struct imxuart_softc *sc;
        struct tty *tp;
        int s;
        int error;

        sc = device_lookup_private(&imxuart_cd, IMXUART_UNIT(dev));
        if (sc == NULL || !ISSET(sc->sc_hwflags, IMXUART_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, IMXUART_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;


#ifdef notyet
                if (sc->enable) {
                        if ((*sc->enable)(sc)) {
                                splx(s);
                                aprint_error_dev(sc->sc_dev,
                                    "device enable failed\n");
                                return (EIO);
                        }
                        sc->enabled = 1;
                }
#endif

                mutex_spin_enter(&sc->sc_lock);

                imxuart_disable_all_interrupts(sc);

                /* Fetch the current modem control status, needed later. */

#ifdef  IMXUART_PPS
                /* Clear PPS capture state on first open. */
                mutex_spin_enter(&timecounter_lock);
                memset(&sc->sc_pps_state, 0, sizeof(sc->sc_pps_state));
                sc->sc_pps_state.ppscap = PPS_CAPTUREASSERT | PPS_CAPTURECLEAR;
                pps_init(&sc->sc_pps_state);
                mutex_spin_exit(&timecounter_lock);
#endif

                mutex_spin_exit(&sc->sc_lock);

                /*
                 * Initialize the termios status to the defaults.  Add in the
                 * sticky bits from TIOCSFLAGS.
                 */
                if (ISSET(sc->sc_hwflags, IMXUART_HW_CONSOLE)) {
                        t.c_ospeed = imxuconsrate;
                        t.c_cflag = imxuconscflag;
                } else {
                        t.c_ospeed = TTYDEF_SPEED;
                        t.c_cflag = TTYDEF_CFLAG;
                }
                t.c_ispeed = t.c_ospeed;
                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 imxuparam() will do something. */
                tp->t_ospeed = 0;
                (void) imxuparam(tp, &t);
                tp->t_iflag = TTYDEF_IFLAG;
                tp->t_oflag = TTYDEF_OFLAG;
                tp->t_lflag = TTYDEF_LFLAG;
                ttychars(tp);
                ttsetwater(tp);

                mutex_spin_enter(&sc->sc_lock);

                /*
                 * 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.
                 */
                imxuart_modem(sc, 1);

                /* Clear the input ring, and unblock. */
                sc->sc_rbuf_in = sc->sc_rbuf_out = 0;
                imxuart_iflush(sc);
                CLR(sc->sc_rx_flags, IMXUART_RX_ANY_BLOCK);
                imxuart_hwiflow(sc);

                /* Turn on interrupts. */
                imxuart_control_rxint(sc, true);

#ifdef IMXUART_DEBUG
                if (imxuart_debug)
                        imxustatus(sc, "imxuopen  ");
#endif

                mutex_spin_exit(&sc->sc_lock);
        }

        splx(s);

#if 0
        error = ttyopen(tp, IMXUART_DIALOUT(dev), ISSET(flag, O_NONBLOCK));
#else
        error = ttyopen(tp, 1, ISSET(flag, O_NONBLOCK));
#endif
        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.
                 */
                imxuart_shutdown(sc);
        }

        return (error);
}

int
imxuclose(dev_t dev, int flag, int mode, struct lwp *l)
{
        struct imxuart_softc *sc =
            device_lookup_private(&imxuart_cd, IMXUART_UNIT(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 (IMXUART_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.
                 */
                imxuart_shutdown(sc);
        }

        return (0);
}

int
imxuread(dev_t dev, struct uio *uio, int flag)
{
        struct imxuart_softc *sc =
            device_lookup_private(&imxuart_cd, IMXUART_UNIT(dev));
        struct tty *tp = sc->sc_tty;

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

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

int
imxuwrite(dev_t dev, struct uio *uio, int flag)
{
        struct imxuart_softc *sc =
            device_lookup_private(&imxuart_cd, IMXUART_UNIT(dev));
        struct tty *tp = sc->sc_tty;

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

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

int
imxupoll(dev_t dev, int events, struct lwp *l)
{
        struct imxuart_softc *sc =
            device_lookup_private(&imxuart_cd, IMXUART_UNIT(dev));
        struct tty *tp = sc->sc_tty;

        if (IMXUART_ISALIVE(sc) == 0)
                return (POLLHUP);

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

struct tty *
imxutty(dev_t dev)
{
        struct imxuart_softc *sc =
            device_lookup_private(&imxuart_cd, IMXUART_UNIT(dev));
        struct tty *tp = sc->sc_tty;

        return (tp);
}

int
imxuioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
{
        struct imxuart_softc *sc;
        struct tty *tp;
        int error;

        sc = device_lookup_private(&imxuart_cd, IMXUART_UNIT(dev));
        if (sc == NULL)
                return ENXIO;
        if (IMXUART_ISALIVE(sc) == 0)
                return (EIO);

        tp = sc->sc_tty;

        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;
        switch (cmd) {
        case TIOCSFLAGS:
                error = kauth_authorize_device_tty(l->l_cred,
                    KAUTH_DEVICE_TTY_PRIVSET, tp);
                break;
        default:
                /* nothing */
                break;
        }
        if (error) {
                return error;
        }

        mutex_spin_enter(&sc->sc_lock);

        switch (cmd) {
        case TIOCSBRK:
                imxuart_break(sc, true);
                break;

        case TIOCCBRK:
                imxuart_break(sc, false);
                break;

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

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

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

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

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

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

#ifdef notyet
        case PPS_IOC_CREATE:
        case PPS_IOC_DESTROY:
        case PPS_IOC_GETPARAMS:
        case PPS_IOC_SETPARAMS:
        case PPS_IOC_GETCAP:
        case PPS_IOC_FETCH:
#ifdef PPS_SYNC
        case PPS_IOC_KCBIND:
#endif
                mutex_spin_enter(&timecounter_lock);
                error = pps_ioctl(cmd, data, &sc->sc_pps_state);
                mutex_spin_exit(&timecounter_lock);
                break;

        case TIOCDCDTIMESTAMP:  /* XXX old, overloaded  API used by xntpd v3 */
                mutex_spin_enter(&timecounter_lock);
#ifndef PPS_TRAILING_EDGE
                TIMESPEC_TO_TIMEVAL((struct timeval *)data,
                    &sc->sc_pps_state.ppsinfo.assert_timestamp);
#else
                TIMESPEC_TO_TIMEVAL((struct timeval *)data,
                    &sc->sc_pps_state.ppsinfo.clear_timestamp);
#endif
                mutex_spin_exit(&timecounter_lock);
                break;
#endif

        default:
                error = EPASSTHROUGH;
                break;
        }

        mutex_spin_exit(&sc->sc_lock);

#ifdef IMXUART_DEBUG
        if (imxuart_debug)
                imxustatus(sc, "imxuioctl ");
#endif

        return (error);
}

integrate void
imxuart_schedrx(struct imxuart_softc *sc)
{
        sc->sc_rx_ready = 1;

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

void
imxuart_break(struct imxuart_softc *sc, bool onoff)
{
        bus_space_tag_t iot = sc->sc_regs.ur_iot;
        bus_space_handle_t ioh = sc->sc_regs.ur_ioh;

        if (onoff)
                SET(sc->sc_ucr1, IMX_UCR1_SNDBRK);
        else
                CLR(sc->sc_ucr1, IMX_UCR1_SNDBRK);

        bus_space_write_4(iot, ioh, IMX_UCR1, sc->sc_ucr1);
}

void
imxuart_modem(struct imxuart_softc *sc, int onoff)
{
#ifdef notyet
        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
                        imxuart_loadchannelregs(sc);
        }
#endif
}

/*
 * RTS output is controlled by UCR2.CTS bit.
 * DTR output is controlled by UCR3.DSR bit.
 * (i.MX reference manual uses names in DCE mode)
 *
 * note: if UCR2.CTSC == 1 for automatic HW flow control, UCR2.CTS is ignored.
 */
void
tiocm_to_imxu(struct imxuart_softc *sc, u_long how, int ttybits)
{
        bus_space_tag_t iot = sc->sc_regs.ur_iot;
        bus_space_handle_t ioh = sc->sc_regs.ur_ioh;

        uint32_t ucr2 = sc->sc_ucr2_d;
        uint32_t ucr3 = sc->sc_ucr3;

        uint32_t ucr2_mask = 0;
        uint32_t ucr3_mask = 0;


        if (ISSET(ttybits, TIOCM_DTR))
                ucr3_mask = IMX_UCR3_DSR;
        if (ISSET(ttybits, TIOCM_RTS))
                ucr2_mask = IMX_UCR2_CTS;

        switch (how) {
        case TIOCMBIC:
                CLR(ucr2, ucr2_mask);
                CLR(ucr3, ucr3_mask);
                break;

        case TIOCMBIS:
                SET(ucr2, ucr2_mask);
                SET(ucr3, ucr3_mask);
                break;

        case TIOCMSET:
                CLR(ucr2, ucr2_mask);
                CLR(ucr3, ucr3_mask);
                SET(ucr2, ucr2_mask);
                SET(ucr3, ucr3_mask);
                break;
        }

        if (ucr3 != sc->sc_ucr3) {
                bus_space_write_4(iot, ioh, IMX_UCR3, ucr3);
                sc->sc_ucr3 = ucr3;
        }

        if (ucr2 == sc->sc_ucr2_d)
                return;

        sc->sc_ucr2_d = ucr2;
        /* update CTS bit only */
        ucr2 = (sc->sc_ucr2 & ~IMX_UCR2_CTS) |
            (ucr2 & IMX_UCR2_CTS);

        bus_space_write_4(iot, ioh, IMX_UCR2, ucr2);
        sc->sc_ucr2 = ucr2;
}

int
imxuart_to_tiocm(struct imxuart_softc *sc)
{
        bus_space_tag_t iot = sc->sc_regs.ur_iot;
        bus_space_handle_t ioh = sc->sc_regs.ur_ioh;
        int ttybits = 0;
        uint32_t usr[2];

        if (ISSET(sc->sc_ucr3, IMX_UCR3_DSR))
                SET(ttybits, TIOCM_DTR);
        if (ISSET(sc->sc_ucr2, IMX_UCR2_CTS))
                SET(ttybits, TIOCM_RTS);

        bus_space_read_region_4(iot, ioh, IMX_USR1, usr, 2);

        if (ISSET(usr[0], IMX_USR1_RTSS))
                SET(ttybits, TIOCM_CTS);

        if (ISSET(usr[1], IMX_USR2_DCDIN))
                SET(ttybits, TIOCM_CD);

#if 0
        /* XXXbsh: I couldn't find the way to read ipp_uart_dsr_dte_i signal,
           although there are bits in UART registers to detect delta of DSR.
        */
        if (ISSET(imxubits, MSR_DSR))
                SET(ttybits, TIOCM_DSR);
#endif

        if (ISSET(usr[1], IMX_USR2_RIIN))
                SET(ttybits, TIOCM_RI);


#ifdef  notyet
        if (ISSET(sc->sc_ier, IER_ERXRDY | IER_ETXRDY | IER_ERLS | IER_EMSC))
                SET(ttybits, TIOCM_LE);
#endif

        return (ttybits);
}

static uint32_t
cflag_to_ucr2(tcflag_t cflag, uint32_t oldval)
{
        uint32_t val = oldval;

        CLR(val,IMX_UCR2_WS|IMX_UCR2_PREN|IMX_UCR2_PROE|IMX_UCR2_STPB);

        switch (cflag & CSIZE) {
        case CS5:
        case CS6:
                /* not suppreted. use 7-bits */
        case CS7:
                break;
        case CS8:
                SET(val, IMX_UCR2_WS);
                break;
        }


        if (ISSET(cflag, PARENB)) {
                SET(val, IMX_UCR2_PREN);

                /* odd parity */
                if (!ISSET(cflag, PARODD))
                        SET(val, IMX_UCR2_PROE);
        }

        if (ISSET(cflag, CSTOPB))
                SET(val, IMX_UCR2_STPB);

        val |= IMX_UCR2_TXEN| IMX_UCR2_RXEN|IMX_UCR2_SRST;

        return val;
}

int
imxuparam(struct tty *tp, struct termios *t)
{
        struct imxuart_softc *sc =
            device_lookup_private(&imxuart_cd, IMXUART_UNIT(tp->t_dev));
        struct imxuart_baudrate_ratio ratio;
        uint32_t ucr2;
        bool change_speed = tp->t_ospeed != t->c_ospeed;

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

        /* Check requested parameters. */
        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, IMXUART_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 ( !change_speed && tp->t_cflag == t->c_cflag)
                return (0);

        if (change_speed) {
                /* calculate baudrate modulator value */
                if (imxuspeed(t->c_ospeed, &ratio) < 0)
                        return (EINVAL);
                sc->sc_ratio = ratio;
        }

        ucr2 = cflag_to_ucr2(t->c_cflag, sc->sc_ucr2_d);

        mutex_spin_enter(&sc->sc_lock);

#if 0   /* flow control stuff.  not yet */
        /*
         * 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;
                sc->sc_efr = EFR_AUTORTS | EFR_AUTOCTS;
        } 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;
                sc->sc_efr = 0;
        } else {
                /*
                 * If no flow control, then always set RTS.  This will make
                 * the other side happy if it mistakenly thinks we're doing
                 * RTS/CTS flow control.
                 */
                sc->sc_mcr_dtr = MCR_DTR | MCR_RTS;
                sc->sc_mcr_rts = 0;
                sc->sc_msr_cts = 0;
                sc->sc_efr = 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;
#endif

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

        if (!change_speed && ucr2 == sc->sc_ucr2_d) {
                /* noop */
        }
        else if (!sc->sc_pending && !sc->sc_tx_busy) {
                if (ucr2 != sc->sc_ucr2_d) {
                        sc->sc_ucr2_d = ucr2;
                        imxuart_load_params(sc);
                }
                if (change_speed)
                        imxuart_load_speed(sc);
        }
        else {
                if (!sc->sc_pending) {
                        sc->sc_heldtbc = sc->sc_tbc;
                        sc->sc_tbc = 0;
                }
                sc->sc_pending |=
                    (ucr2 == sc->sc_ucr2_d ? 0 : IMXUART_PEND_PARAM) |
                    (change_speed ? 0 : IMXUART_PEND_SPEED);
                sc->sc_ucr2_d = ucr2;
        }

        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, IMXUART_RX_TTY_OVERFLOWED)) {
                        CLR(sc->sc_rx_flags, IMXUART_RX_TTY_OVERFLOWED);
                        imxuart_schedrx(sc);
                }
                if (ISSET(sc->sc_rx_flags,
                        IMXUART_RX_TTY_BLOCKED|IMXUART_RX_IBUF_BLOCKED)) {
                        CLR(sc->sc_rx_flags,
                            IMXUART_RX_TTY_BLOCKED|IMXUART_RX_IBUF_BLOCKED);
                        imxuart_hwiflow(sc);
                }
        } else {
                sc->sc_r_hiwat = imxuart_rbuf_hiwat;
                sc->sc_r_lowat = imxuart_rbuf_lowat;
        }

        mutex_spin_exit(&sc->sc_lock);

#if 0
        /*
         * 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));
#else
        /* XXX: always report that we have DCD */
        (void) (*tp->t_linesw->l_modem)(tp, 1);
#endif

#ifdef IMXUART_DEBUG
        if (imxuart_debug)
                imxustatus(sc, "imxuparam ");
#endif

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

        return (0);
}

void
imxuart_iflush(struct imxuart_softc *sc)
{
        bus_space_tag_t iot = sc->sc_regs.ur_iot;
        bus_space_handle_t ioh = sc->sc_regs.ur_ioh;
#ifdef DIAGNOSTIC
        uint32_t reg = 0xffff;
#endif
        int timo;

        timo = 50000;
        /* flush any pending I/O */
        while (ISSET(bus_space_read_4(iot, ioh, IMX_USR2), IMX_USR2_RDR)
            && --timo)
#ifdef DIAGNOSTIC
                reg =
#else
                    (void)
#endif
                    bus_space_read_4(iot, ioh, IMX_URXD);
#ifdef DIAGNOSTIC
        if (!timo)
                aprint_error_dev(sc->sc_dev, "imxuart_iflush timeout %02x\n", reg);
#endif
}

int
imxuhwiflow(struct tty *tp, int block)
{
        struct imxuart_softc *sc =
            device_lookup_private(&imxuart_cd, IMXUART_UNIT(tp->t_dev));

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

#ifdef notyet
        if (sc->sc_mcr_rts == 0)
                return (0);
#endif

        mutex_spin_enter(&sc->sc_lock);

        if (block) {
                if (!ISSET(sc->sc_rx_flags, IMXUART_RX_TTY_BLOCKED)) {
                        SET(sc->sc_rx_flags, IMXUART_RX_TTY_BLOCKED);
                        imxuart_hwiflow(sc);
                }
        } else {
                if (ISSET(sc->sc_rx_flags, IMXUART_RX_TTY_OVERFLOWED)) {
                        CLR(sc->sc_rx_flags, IMXUART_RX_TTY_OVERFLOWED);
                        imxuart_schedrx(sc);
                }
                if (ISSET(sc->sc_rx_flags, IMXUART_RX_TTY_BLOCKED)) {
                        CLR(sc->sc_rx_flags, IMXUART_RX_TTY_BLOCKED);
                        imxuart_hwiflow(sc);
                }
        }

        mutex_spin_exit(&sc->sc_lock);
        return (1);
}

/*
 * (un)block input via hw flowcontrol
 */
void
imxuart_hwiflow(struct imxuart_softc *sc)
{
#ifdef notyet
        struct imxuart_regs *regsp= &sc->sc_regs;

        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);
        }
        UR_WRITE_1(regsp, IMXUART_REG_MCR, sc->sc_mcr_active);
#endif
}


void
imxustart(struct tty *tp)
{
        struct imxuart_softc *sc =
            device_lookup_private(&imxuart_cd, IMXUART_UNIT(tp->t_dev));
        int s;
        u_char *tba;
        int tbc;
        u_int n;
        u_int space;
        bus_space_tag_t iot = sc->sc_regs.ur_iot;
        bus_space_handle_t ioh = sc->sc_regs.ur_ioh;

        if (IMXUART_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. */
        tba = tp->t_outq.c_cf;
        tbc = ndqb(&tp->t_outq, 0);

        mutex_spin_enter(&sc->sc_lock);

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

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

        space = imxuart_txfifo_space(sc);
        n = MIN(sc->sc_tbc, space);

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

        /* Enable transmit completion interrupts */
        imxuart_control_txint(sc, true);

        mutex_spin_exit(&sc->sc_lock);
out:
        splx(s);
        return;
}

/*
 * Stop output on a line.
 */
void
imxustop(struct tty *tp, int flag)
{
        struct imxuart_softc *sc =
            device_lookup_private(&imxuart_cd, IMXUART_UNIT(tp->t_dev));

        mutex_spin_enter(&sc->sc_lock);
        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);
        }
        mutex_spin_exit(&sc->sc_lock);
}

void
imxudiag(void *arg)
{
#ifdef notyet
        struct imxuart_softc *sc = arg;
        int overflows, floods;

        mutex_spin_enter(&sc->sc_lock);
        overflows = sc->sc_overflows;
        sc->sc_overflows = 0;
        floods = sc->sc_floods;
        sc->sc_floods = 0;
        sc->sc_errors = 0;
        mutex_spin_exit(&sc->sc_lock);

        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");
#endif
}

integrate void
imxuart_rxsoft(struct imxuart_softc *sc, struct tty *tp)
{
        int (*rint)(int, struct tty *) = tp->t_linesw->l_rint;
        u_int cc, scc, outp;
        uint16_t data;
        u_int code;

        scc = cc = IMXUART_RBUF_AVAIL(sc);

#if 0
        if (cc == imxuart_rbuf_size-1) {
                sc->sc_floods++;
                if (sc->sc_errors++ == 0)
                        callout_reset(&sc->sc_diag_callout, 60 * hz,
                            imxudiag, sc);
        }
#endif

        /* If not yet open, drop the entire buffer content here */
        if (!ISSET(tp->t_state, TS_ISOPEN)) {
                sc->sc_rbuf_out = sc->sc_rbuf_in;
                cc = 0;
        }

        outp = sc->sc_rbuf_out;

#define ERRBITS (IMX_URXD_PRERR|IMX_URXD_BRK|IMX_URXD_FRMERR|IMX_URXD_OVRRUN)

        while (cc) {
                data = sc->sc_rbuf[outp];
                code = data & IMX_URXD_RX_DATA;
                if (ISSET(data, ERRBITS)) {
                        if (sc->sc_errors.err == 0)
                                callout_reset(&sc->sc_diag_callout,
                                    60 * hz, imxudiag, sc);
                        if (ISSET(data, IMX_URXD_OVRRUN))
                                sc->sc_errors.ovrrun++;
                        if (ISSET(data, IMX_URXD_BRK)) {
                                sc->sc_errors.brk++;
                                SET(code, TTY_FE);
                        }
                        if (ISSET(data, IMX_URXD_FRMERR)) {
                                sc->sc_errors.frmerr++;
                                SET(code, TTY_FE);
                        }
                        if (ISSET(data, IMX_URXD_PRERR)) {
                                sc->sc_errors.prerr++;
                                SET(code, TTY_PE);
                        }
                }
                if ((*rint)(code, tp) == -1) {
                        /*
                         * The line discipline's buffer is out of space.
                         */
                        if (!ISSET(sc->sc_rx_flags, IMXUART_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.
                                 */
                                sc->sc_rbuf_out = sc->sc_rbuf_in;
                                cc = 0;
                        } else {
                                /*
                                 * Don't schedule any more receive processing
                                 * until the line discipline tells us there's
                                 * space available (through imxuhwiflow()).
                                 * Leave the rest of the data in the input
                                 * buffer.
                                 */
                                SET(sc->sc_rx_flags, IMXUART_RX_TTY_OVERFLOWED);
                        }
                        break;
                }
                outp = IMXUART_RBUF_INC(sc, outp, 1);
                cc--;
        }

        if (cc != scc) {
                sc->sc_rbuf_out = outp;
                mutex_spin_enter(&sc->sc_lock);

                cc = IMXUART_RBUF_SPACE(sc);

                /* Buffers should be ok again, release possible block. */
                if (cc >= sc->sc_r_lowat) {
                        if (ISSET(sc->sc_rx_flags, IMXUART_RX_IBUF_OVERFLOWED)) {
                                CLR(sc->sc_rx_flags, IMXUART_RX_IBUF_OVERFLOWED);
                                imxuart_control_rxint(sc, true);
                        }
                        if (ISSET(sc->sc_rx_flags, IMXUART_RX_IBUF_BLOCKED)) {
                                CLR(sc->sc_rx_flags, IMXUART_RX_IBUF_BLOCKED);
                                imxuart_hwiflow(sc);
                        }
                }
                mutex_spin_exit(&sc->sc_lock);
        }
}

integrate void
imxuart_txsoft(struct imxuart_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
imxuart_stsoft(struct imxuart_softc *sc, struct tty *tp)
{
#ifdef notyet
        u_char msr, delta;

        mutex_spin_enter(&sc->sc_lock);
        msr = sc->sc_msr;
        delta = sc->sc_msr_delta;
        sc->sc_msr_delta = 0;
        mutex_spin_exit(&sc->sc_lock);

        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;
                }
        }

#endif
#ifdef IMXUART_DEBUG
        if (imxuart_debug)
                imxustatus(sc, "imxuart_stsoft");
#endif
}

void
imxusoft(void *arg)
{
        struct imxuart_softc *sc = arg;
        struct tty *tp;

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

        tp = sc->sc_tty;

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

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

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

int
imxuintr(void *arg)
{
        struct imxuart_softc *sc = arg;
        uint32_t usr1, usr2;
        bus_space_tag_t iot = sc->sc_regs.ur_iot;
        bus_space_handle_t ioh = sc->sc_regs.ur_ioh;


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

        mutex_spin_enter(&sc->sc_lock);

        usr2 = bus_space_read_4(iot, ioh, IMX_USR2);


        do {
                bus_space_write_4(iot, ioh, IMX_USR2,
                    usr2 & (IMX_USR2_BRCD|IMX_USR2_ORE));
                if (usr2 & IMX_USR2_BRCD) {
                        /* Break signal detected */
                        int cn_trapped = 0;

                        cn_check_magic(sc->sc_tty->t_dev,
                                       CNC_BREAK, imxuart_cnm_state);
                        if (cn_trapped)
                                goto next;
#if defined(KGDB) && !defined(DDB)
                        if (ISSET(sc->sc_hwflags, IMXUART_HW_KGDB)) {
                                kgdb_connect(1);
                                goto next;
                        }
#endif
                }

                if (usr2 & IMX_USR2_RDR)
                        imxuintr_read(sc);

#ifdef  IMXUART_PPS
                {
                        u_char  msr, delta;

                        msr = CSR_READ_1(regsp, IMXUART_REG_MSR);
                        delta = msr ^ sc->sc_msr;
                        sc->sc_msr = msr;
                        if ((sc->sc_pps_state.ppsparam.mode & PPS_CAPTUREBOTH) &&
                            (delta & MSR_DCD)) {
                                mutex_spin_enter(&timecounter_lock);
                                pps_capture(&sc->sc_pps_state);
                                pps_event(&sc->sc_pps_state,
                                    (msr & MSR_DCD) ?
                                    PPS_CAPTUREASSERT :
                                    PPS_CAPTURECLEAR);
                                mutex_spin_exit(&timecounter_lock);
                        }
                }
#endif

#ifdef notyet
                /*
                 * 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 IMXUART_DEBUG
                                if (imxuart_debug)
                                        imxustatus(sc, "imxuintr  ");
#endif
                        }

                        sc->sc_st_check = 1;
                }
#endif

next:
                usr2 = bus_space_read_4(iot, ioh, IMX_USR2);
        } while (usr2 & (IMX_USR2_RDR|IMX_USR2_BRCD));

        usr1 = bus_space_read_4(iot, ioh, IMX_USR1);
        if (usr1 & IMX_USR1_TRDY)
                imxuintr_send(sc);

        mutex_spin_exit(&sc->sc_lock);

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

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

        return (1);
}


/*
 * called when there is least one character in rxfifo
 *
 */

static void
imxuintr_read(struct imxuart_softc *sc)
{
        int cc;
        uint16_t rd;
        uint32_t usr2;
        bus_space_tag_t iot = sc->sc_regs.ur_iot;
        bus_space_handle_t ioh = sc->sc_regs.ur_ioh;

        cc = IMXUART_RBUF_SPACE(sc);

        /* clear aging timer interrupt */
        bus_space_write_4(iot, ioh, IMX_USR1, IMX_USR1_AGTIM);

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

                sc->sc_rbuf[sc->sc_rbuf_in] = rd =
                    bus_space_read_4(iot, ioh, IMX_URXD);

                cn_check_magic(sc->sc_tty->t_dev,
                    rd & 0xff, imxuart_cnm_state);

                if (!cn_trapped) {
#if defined(DDB) && defined(DDB_KEYCODE)
                        /*
                         * Temporary hack so that I can force the kernel into
                         * the debugger via the serial port
                         */
                        if ((rd & 0xff) == DDB_KEYCODE)
                                Debugger();
#endif
                        sc->sc_rbuf_in = IMXUART_RBUF_INC(sc, sc->sc_rbuf_in, 1);
                        cc--;
                }

                usr2 = bus_space_read_4(iot, ioh, IMX_USR2);
                if (!(usr2 & IMX_USR2_RDR))
                        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.
         */
        if (!ISSET(sc->sc_rx_flags, IMXUART_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, IMXUART_RX_IBUF_BLOCKED) &&
            cc < sc->sc_r_hiwat) {
                sc->sc_rx_flags |= IMXUART_RX_IBUF_BLOCKED;
                imxuart_hwiflow(sc);
        }

        /*
         * If we're out of space, disable receive interrupts
         * until the queue has drained a bit.
         */
        if (!cc) {
                sc->sc_rx_flags |= IMXUART_RX_IBUF_OVERFLOWED;
                imxuart_control_rxint(sc, false);
        }
}



/*
 * find how many chars we can put into tx-fifo
 */
static u_int
imxuart_txfifo_space(struct imxuart_softc *sc)
{
        uint32_t usr1, usr2;
        u_int cc;
        bus_space_tag_t iot = sc->sc_regs.ur_iot;
        bus_space_handle_t ioh = sc->sc_regs.ur_ioh;

        usr2 = bus_space_read_4(iot, ioh, IMX_USR2);
        if (usr2 & IMX_USR2_TXFE)
                cc = sc->sc_txfifo_len;
        else {
                usr1 = bus_space_read_4(iot, ioh, IMX_USR1);
                if (usr1 & IMX_USR1_TRDY)
                        cc = sc->sc_txfifo_thresh;
                else
                        cc = 0;
        }

        return cc;
}

void
imxuintr_send(struct imxuart_softc *sc)
{
        uint32_t usr2;
        bus_space_tag_t iot = sc->sc_regs.ur_iot;
        bus_space_handle_t ioh = sc->sc_regs.ur_ioh;
        int cc = 0;

        usr2 = bus_space_read_4(iot, ioh, IMX_USR2);

        if (sc->sc_pending) {
                if (usr2 & IMX_USR2_TXFE) {
                        imxuart_load_pendings(sc);
                        sc->sc_tbc = sc->sc_heldtbc;
                        sc->sc_heldtbc = 0;
                }
                else {
                        /* wait for TX fifo empty */
                        imxuart_control_txint(sc, true);
                        return;
                }
        }

        cc = imxuart_txfifo_space(sc);
        cc = MIN(cc, sc->sc_tbc);

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

        if (sc->sc_tbc > 0)
                imxuart_control_txint(sc, true);
        else {
                /* no more chars to send.
                   we don't need tx interrupt any more. */
                imxuart_control_txint(sc, false);
                if (sc->sc_tx_busy) {
                        sc->sc_tx_busy = 0;
                        sc->sc_tx_done = 1;
                }
        }
}

static void
imxuart_disable_all_interrupts(struct imxuart_softc *sc)
{
        bus_space_tag_t iot = sc->sc_regs.ur_iot;
        bus_space_handle_t ioh = sc->sc_regs.ur_ioh;

        sc->sc_ucr1 &= ~IMXUART_INTRS_UCR1;
        sc->sc_ucr2 &= ~IMXUART_INTRS_UCR2;
        sc->sc_ucr3 &= ~IMXUART_INTRS_UCR3;
        sc->sc_ucr4 &= ~IMXUART_INTRS_UCR4;


        bus_space_write_region_4(iot, ioh, IMX_UCR1, sc->sc_ucr, 4);
}

static void
imxuart_control_rxint(struct imxuart_softc *sc, bool enable)
{
        bus_space_tag_t iot = sc->sc_regs.ur_iot;
        bus_space_handle_t ioh = sc->sc_regs.ur_ioh;
        uint32_t ucr1, ucr2;

        ucr1 = sc->sc_ucr1;
        ucr2 = sc->sc_ucr2;

        if (enable) {
                ucr1 |= IMX_UCR1_RRDYEN;
                ucr2 |= IMX_UCR2_ATEN;
        }
        else {
                ucr1 &= ~IMX_UCR1_RRDYEN;
                ucr2 &= ~IMX_UCR2_ATEN;
        }

        if (ucr1 != sc->sc_ucr1 || ucr2 != sc->sc_ucr2) {
                sc->sc_ucr1 = ucr1;
                sc->sc_ucr2 = ucr2;
                bus_space_write_region_4(iot, ioh, IMX_UCR1, sc->sc_ucr, 2);
        }
}

static void
imxuart_control_txint(struct imxuart_softc *sc, bool enable)
{
        bus_space_tag_t iot = sc->sc_regs.ur_iot;
        bus_space_handle_t ioh = sc->sc_regs.ur_ioh;
        uint32_t ucr1;
        uint32_t mask;

        /* if parameter change is pending, get interrupt when Tx fifo
           is completely empty.  otherwise, get interrupt when txfifo
           has less characters than threshold */
        mask = sc->sc_pending ? IMX_UCR1_TXMPTYEN : IMX_UCR1_TRDYEN;

        ucr1 = sc->sc_ucr1;

        CLR(ucr1, IMX_UCR1_TXMPTYEN|IMX_UCR1_TRDYEN);
        if (enable)
                SET(ucr1, mask);

        if (ucr1 != sc->sc_ucr1) {
                bus_space_write_4(iot, ioh, IMX_UCR1, ucr1);
                sc->sc_ucr1 = ucr1;
        }
}


static void
imxuart_load_params(struct imxuart_softc *sc)
{
        uint32_t ucr2;
        bus_space_tag_t iot = sc->sc_regs.ur_iot;
        bus_space_handle_t ioh = sc->sc_regs.ur_ioh;

        ucr2 = (sc->sc_ucr2_d & ~IMX_UCR2_ATEN) |
            (sc->sc_ucr2 & IMX_UCR2_ATEN);

        bus_space_write_4(iot, ioh, IMX_UCR2, ucr2);
        sc->sc_ucr2 = ucr2;
}

static void
imxuart_load_speed(struct imxuart_softc *sc)
{
        bus_space_tag_t iot = sc->sc_regs.ur_iot;
        bus_space_handle_t ioh = sc->sc_regs.ur_ioh;
        int n, rfdiv, ufcr;

#ifdef notyet
        /*
         * Set the FIFO threshold based on the receive speed.
         *
         *  * If it's a low speed, it's probably a mouse or some other
         *    interactive device, so set the threshold low.
         *  * If it's a high speed, trim the trigger level down to prevent
         *    overflows.
         *  * Otherwise set it a bit higher.
         */
        if (t->c_ospeed <= 1200)
                sc->sc_fifo = FIFO_ENABLE | FIFO_TRIGGER_1;
        else if (t->c_ospeed <= 38400)
                sc->sc_fifo = FIFO_ENABLE | FIFO_TRIGGER_8;
        else
                sc->sc_fifo = FIFO_ENABLE | FIFO_TRIGGER_4;
#endif

        n = 32 - sc->sc_txfifo_thresh;
        n = MAX(2, n);

        rfdiv = IMX_UFCR_DIVIDER_TO_RFDIV(imxuart_freqdiv);

        ufcr = (n << IMX_UFCR_TXTL_SHIFT) |
                (rfdiv << IMX_UFCR_RFDIV_SHIFT) |
                (16 << IMX_UFCR_RXTL_SHIFT);

        /* keep DCE/DTE bit */
        ufcr |= bus_space_read_4(iot, ioh, IMX_UFCR) & IMX_UFCR_DCEDTE;

        bus_space_write_4(iot, ioh, IMX_UFCR, ufcr);

        /* UBIR must updated before UBMR */
        bus_space_write_4(iot, ioh,
            IMX_UBIR, sc->sc_ratio.numerator);
        bus_space_write_4(iot, ioh,
            IMX_UBMR, sc->sc_ratio.modulator);


}


static void
imxuart_load_pendings(struct imxuart_softc *sc)
{
        if (sc->sc_pending & IMXUART_PEND_PARAM)
                imxuart_load_params(sc);
        if (sc->sc_pending & IMXUART_PEND_SPEED)
                imxuart_load_speed(sc);
        sc->sc_pending = 0;
}

/*
 * 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 READAHEAD_RING_LEN      16
static int imxuart_readahead[READAHEAD_RING_LEN];
static int imxuart_readahead_in = 0;
static int imxuart_readahead_out = 0;
#define READAHEAD_IS_EMPTY()    (imxuart_readahead_in==imxuart_readahead_out)
#define READAHEAD_IS_FULL()     \
        (((imxuart_readahead_in+1) & (READAHEAD_RING_LEN-1)) ==imxuart_readahead_out)

int
imxuart_common_getc(dev_t dev, struct imxuart_regs *regsp)
{
        int s = splserial();
        u_char c;
        bus_space_tag_t iot = regsp->ur_iot;
        bus_space_handle_t ioh = regsp->ur_ioh;
        uint32_t usr2;

        /* got a character from reading things earlier */
        if (!READAHEAD_IS_EMPTY()) {
                c = imxuart_readahead[imxuart_readahead_out];
                imxuart_readahead_out = (imxuart_readahead_out + 1) &
                    (READAHEAD_RING_LEN-1);
                splx(s);
                return (c);
        }

        /* block until a character becomes available */
        while (!((usr2 = bus_space_read_4(iot, ioh, IMX_USR2)) & IMX_USR2_RDR))
                continue;

        c = 0xff & bus_space_read_4(iot, ioh, IMX_URXD);

        {
                int cn_trapped __unused = 0;
                if (!db_active)
                        cn_check_magic(dev, c, imxuart_cnm_state);
        }
        splx(s);
        return (c);
}

void
imxuart_common_putc(dev_t dev, struct imxuart_regs *regsp, int c)
{
        int s = splserial();
        int cin, timo;
        bus_space_tag_t iot = regsp->ur_iot;
        bus_space_handle_t ioh = regsp->ur_ioh;
        uint32_t usr2;

        if (!READAHEAD_IS_FULL() &&
            ((usr2 = bus_space_read_4(iot, ioh, IMX_USR2)) & IMX_USR2_RDR)) {

                int __attribute__((__unused__))cn_trapped = 0;
                cin = bus_space_read_4(iot, ioh, IMX_URXD);
                cn_check_magic(dev, cin & 0xff, imxuart_cnm_state);
                imxuart_readahead[imxuart_readahead_in] = cin & 0xff;
                imxuart_readahead_in = (imxuart_readahead_in + 1) &
                    (READAHEAD_RING_LEN-1);
        }

        /* wait for any pending transmission to finish */
        timo = 150000;
        do {
                if (bus_space_read_4(iot, ioh, IMX_USR1) & IMX_USR1_TRDY) {
                        bus_space_write_4(iot, ioh, IMX_UTXD, c);
                        break;
                }
        } while(--timo > 0);

        IMXUART_BARRIER(regsp, BR | BW);

        splx(s);
}

/*
 * Initialize UART
 */
int
imxuart_init(struct imxuart_regs *regsp, int rate, tcflag_t cflag, int domap)
{
        struct imxuart_baudrate_ratio ratio;
        int rfdiv = IMX_UFCR_DIVIDER_TO_RFDIV(imxuart_freqdiv);
        uint32_t ufcr;
        int error;

        if (domap && (error = bus_space_map(regsp->ur_iot, regsp->ur_iobase,
             IMX_UART_SIZE, 0, &regsp->ur_ioh)) != 0)
                return error;

        if (imxuart_freq != 0) {
                if (imxuspeed(rate, &ratio) < 0)
                        return EINVAL;

                /* UBIR must updated before UBMR */
                bus_space_write_4(regsp->ur_iot, regsp->ur_ioh,
                    IMX_UBIR, ratio.numerator);
                bus_space_write_4(regsp->ur_iot, regsp->ur_ioh,
                    IMX_UBMR, ratio.modulator);
        }

        /* XXX: DTREN, DPEC */
        bus_space_write_4(regsp->ur_iot, regsp->ur_ioh, IMX_UCR3,
            IMX_UCR3_DSR|IMX_UCR3_RXDMUXSEL);

        ufcr = bus_space_read_4(regsp->ur_iot, regsp->ur_ioh, IMX_UFCR);
        ufcr &= ~IMX_UFCR_TXTL;
        ufcr |= (8 << IMX_UFCR_TXTL_SHIFT);
        ufcr &= ~IMX_UFCR_RXTL;
        ufcr |= (1 << IMX_UFCR_RXTL_SHIFT);
        if (imxuart_freq != 0) {
                ufcr &= ~IMX_UFCR_RFDIV;
                ufcr |= (rfdiv << IMX_UFCR_RFDIV_SHIFT);
        }
        bus_space_write_4(regsp->ur_iot, regsp->ur_ioh, IMX_UFCR, ufcr);

        if (imxuart_freq != 0) {
                bus_space_write_4(regsp->ur_iot, regsp->ur_ioh, IMX_ONEMS,
                    imxuart_freq / imxuart_freqdiv / 1000);
        }

        bus_space_write_4(regsp->ur_iot, regsp->ur_ioh, IMX_UCR2,
                          IMX_UCR2_IRTS|
                          IMX_UCR2_CTSC|
                          IMX_UCR2_WS|IMX_UCR2_TXEN|
                          IMX_UCR2_RXEN|IMX_UCR2_SRST);
        /* clear status registers */
        bus_space_write_4(regsp->ur_iot, regsp->ur_ioh, IMX_USR1, 0xffff);
        bus_space_write_4(regsp->ur_iot, regsp->ur_ioh, IMX_USR2, 0xffff);


        bus_space_write_4(regsp->ur_iot, regsp->ur_ioh, IMX_UCR1,
            IMX_UCR1_UARTEN);

        return (0);
}


/*
 * Following are all routines needed for UART to act as console
 */
struct consdev imxucons = {
        NULL, NULL, imxucngetc, imxucnputc, imxucnpollc, NULL, NULL, NULL,
        NODEV, CN_NORMAL
};


int
imxuart_cnattach(bus_space_tag_t iot, paddr_t iobase, u_int rate,
    tcflag_t cflag)
{
        struct imxuart_regs regs;
        int res;

        regs.ur_iot = iot;
        regs.ur_iobase = iobase;

        res = imxuart_init(&regs, rate, cflag, true);
        if (res)
                return (res);

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

        imxuconsrate = rate;
        imxuconscflag = cflag;

        imxuconsregs = regs;

        return 0;
}

int
imxucngetc(dev_t dev)
{
        return (imxuart_common_getc(dev, &imxuconsregs));
}

/*
 * Console kernel output character routine.
 */
void
imxucnputc(dev_t dev, int c)
{
        imxuart_common_putc(dev, &imxuconsregs, c);
}

void
imxucnpollc(dev_t dev, int on)
{

        imxuart_readahead_in = 0;
        imxuart_readahead_out = 0;
}

#ifdef KGDB
int
imxuart_kgdb_attach(bus_space_tag_t iot, paddr_t iobase, u_int rate,
    tcflag_t cflag)
{
        int res;

        if (iot == imxuconsregs.ur_iot &&
            iobase == imxuconsregs.ur_iobase) {
#if !defined(DDB)
                return (EBUSY); /* cannot share with console */
#else
                imxu_kgdb_regs.ur_iot = iot;
                imxu_kgdb_regs.ur_ioh = imxuconsregs.ur_ioh;
                imxu_kgdb_regs.ur_iobase = iobase;
#endif
        } else {
                imxu_kgdb_regs.ur_iot = iot;
                imxu_kgdb_regs.ur_iobase = iobase;

                res = imxuart_init(&imxu_kgdb_regs, rate, cflag, true);
                if (res)
                        return (res);

                /*
                 * XXXfvdl this shouldn't be needed, but the cn_magic goo
                 * expects this to be initialized
                 */
                cn_init_magic(&imxuart_cnm_state);
                cn_set_magic("\047\001");
        }

        kgdb_attach(imxuart_kgdb_getc, imxuart_kgdb_putc, &imxu_kgdb_regs);
        kgdb_dev = 123; /* unneeded, only to satisfy some tests */

        return (0);
}

/* ARGSUSED */
int
imxuart_kgdb_getc(void *arg)
{
        struct imxuart_regs *regs = arg;

        return (imxuart_common_getc(NODEV, regs));
}

/* ARGSUSED */
void
imxuart_kgdb_putc(void *arg, int c)
{
        struct imxuart_regs *regs = arg;

        imxuart_common_putc(NODEV, regs, c);
}
#endif /* KGDB */

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

        if (!imxuconsattached &&
            iot == imxuconsregs.ur_iot && iobase == imxuconsregs.ur_iobase)
                help = imxuconsregs.ur_ioh;
#ifdef KGDB
        else if (!imxu_kgdb_attached &&
            iot == imxu_kgdb_regs.ur_iot && iobase == imxu_kgdb_regs.ur_iobase)
                help = imxu_kgdb_regs.ur_ioh;
#endif
        else
                return (0);

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

#ifdef notyet

bool
imxuart_cleanup(device_t self, int how)
{
/*
 * this routine exists to serve as a shutdown hook for systems that
 * have firmware which doesn't interact properly with a imxuart device in
 * FIFO mode.
 */
        struct imxuart_softc *sc = device_private(self);

        if (ISSET(sc->sc_hwflags, IMXUART_HW_FIFO))
                UR_WRITE_1(&sc->sc_regs, IMXUART_REG_FIFO, 0);

        return true;
}
#endif

#ifdef notyet
bool
imxuart_suspend(device_t self PMF_FN_ARGS)
{
        struct imxuart_softc *sc = device_private(self);

        UR_WRITE_1(&sc->sc_regs, IMXUART_REG_IER, 0);
        (void)CSR_READ_1(&sc->sc_regs, IMXUART_REG_IIR);

        return true;
}
#endif

#ifdef notyet
bool
imxuart_resume(device_t self PMF_FN_ARGS)
{
        struct imxuart_softc *sc = device_private(self);

        mutex_spin_enter(&sc->sc_lock);
        imxuart_loadchannelregs(sc);
        mutex_spin_exit(&sc->sc_lock);

        return true;
}
#endif

static void
imxuart_enable_debugport(struct imxuart_softc *sc)
{
        bus_space_tag_t iot = sc->sc_regs.ur_iot;
        bus_space_handle_t ioh = sc->sc_regs.ur_ioh;

        if (sc->sc_hwflags & (IMXUART_HW_CONSOLE|IMXUART_HW_KGDB)) {

                /* Turn on line break interrupt, set carrier. */

                sc->sc_ucr3 |= IMX_UCR3_DSR;
                bus_space_write_4(iot, ioh, IMX_UCR3, sc->sc_ucr3);

                sc->sc_ucr4 |= IMX_UCR4_BKEN;
                bus_space_write_4(iot, ioh, IMX_UCR4, sc->sc_ucr4);

                sc->sc_ucr2 |= IMX_UCR2_TXEN|IMX_UCR2_RXEN|
                    IMX_UCR2_CTS;
                bus_space_write_4(iot, ioh, IMX_UCR2, sc->sc_ucr2);

                sc->sc_ucr1 |= IMX_UCR1_UARTEN;
                bus_space_write_4(iot, ioh, IMX_UCR1, sc->sc_ucr1);
        }
}


void
imxuart_set_frequency(u_int freq, u_int div)
{
        imxuart_freq = freq;
        imxuart_freqdiv = div;
}