/*      $NetBSD: wmcom.c,v 1.10 2023/09/01 08:53:52 andvar Exp $      */
/*
 * Copyright (c) 2012 KIYOHARA Takashi
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: wmcom.c,v 1.10 2023/09/01 08:53:52 andvar Exp $");

#include "rnd.h"

#include <sys/param.h>
#include <sys/bus.h>
#include <sys/conf.h>
#include <sys/device.h>
#include <sys/errno.h>
#include <sys/fcntl.h>
#include <sys/intr.h>
#include <sys/kauth.h>
#include <sys/lwp.h>
#include <sys/malloc.h>
#include <sys/systm.h>
#include <sys/termios.h>
#include <sys/tty.h>
#include <sys/types.h>

#include <ddb/db_active.h>

#include <epoc32/windermere/windermerereg.h>
#include <epoc32/windermere/windermerevar.h>

#include <dev/cons.h>

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

#include "ioconf.h"
#include "locators.h"

#define COMUNIT(x)      TTUNIT(x)
#define COMDIALOUT(x)   TTDIALOUT(x)

#define WMCOM_RING_SIZE 2048

struct wmcom_softc {
        device_t sc_dev;
        bus_space_tag_t sc_iot;
        bus_space_handle_t sc_ioh;

        void *sc_si;

        struct tty *sc_tty;

        u_char *sc_tba;
        u_int sc_tbc;
        u_char *sc_rbuf;
        char *volatile sc_rbget;
        char *volatile sc_rbput;
        volatile int sc_rbavail;

        int sc_tx_done;
        int sc_rx_ready;

        int sc_hwflags;
#define COM_HW_CONSOLE  (1 << 0)
#define COM_HW_DEV_OK   (1 << 1)
#define COM_HW_KGDB     (1 << 2)
        int sc_swflags;

        int sc_flags;
#define WMCOM_IRDA      (1 << 0)

#ifdef RND_COM
        krndsource_t rnd_source;
#endif
};

static int wmcom_match(device_t, cfdata_t, void *);
static void wmcom_attach(device_t, device_t, void *);

static int wmcom_intr(void *);
static void wmcom_soft(void *);

static void wmcom_start(struct tty *);
static int wmcom_param(struct tty *, struct termios *);
static int wmcom_hwiflow(struct tty *, int);

dev_type_open(wmcomopen);
dev_type_close(wmcomclose);
dev_type_read(wmcomread);
dev_type_write(wmcomwrite);
dev_type_ioctl(wmcomioctl);
dev_type_stop(wmcomstop);
dev_type_tty(wmcomtty);
dev_type_poll(wmcompoll);

static void wmcom_iflush(struct wmcom_softc *);
static void wmcom_shutdown(struct wmcom_softc *);
static void wmcom_break(struct wmcom_softc *, int);

static void wmcom_rxsoft(struct wmcom_softc *, struct tty *);

static inline uint32_t wmcom_rate2lcr(int);
static uint8_t wmcom_cflag2fcr(tcflag_t);

static int wmcom_cngetc(dev_t);
static void wmcom_cnputc(dev_t, int);
static void wmcom_cnpollc(dev_t, int);

CFATTACH_DECL_NEW(wmcom, sizeof(struct wmcom_softc),
    wmcom_match, wmcom_attach, NULL, NULL);

const struct cdevsw wmcom_cdevsw = {
        .d_open = wmcomopen,
        .d_close = wmcomclose,
        .d_read = wmcomread,
        .d_write = wmcomwrite,
        .d_ioctl = wmcomioctl,
        .d_stop = wmcomstop,
        .d_tty = wmcomtty,
        .d_poll = wmcompoll,
        .d_mmap = nommap,
        .d_kqfilter = ttykqfilter,
        .d_discard = nodiscard,
        .d_flag = D_TTY
};

static struct cnm_state wmcom_cnm_state;
static vaddr_t wmcom_cnaddr;
static int wmcom_cnrate;
static tcflag_t wmcom_cncflag;


/* ARGSUSED */
static int
wmcom_match(device_t parent, cfdata_t match, void *aux)
{
        struct windermere_attach_args *aa = aux;

        /* Wildcard not accept */
        if (aa->aa_offset == WINDERMERECF_OFFSET_DEFAULT ||
            aa->aa_irq == WINDERMERECF_IRQ_DEFAULT)
                return 0;

        aa->aa_size = UART_SIZE;
        return 1;
}

/* ARGSUSED */
static void
wmcom_attach(device_t parent, device_t self, void *aux)
{
        struct wmcom_softc *sc = device_private(self);
        struct windermere_attach_args *aa = aux;

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

        sc->sc_dev = self;
        if (windermere_bus_space_subregion(aa->aa_iot, *aa->aa_ioh,
                                aa->aa_offset, aa->aa_size, &sc->sc_ioh) != 0) {
                aprint_error_dev(self, "can't map registers\n");
                return;
        }
        sc->sc_iot = aa->aa_iot;
        if (intr_establish(aa->aa_irq, IPL_SERIAL, 0, wmcom_intr, sc) == NULL) {
                aprint_error_dev(self, "can't establish interrupt\n");
                return;
        }

        if (aa->aa_offset == (wmcom_cnaddr & 0xfff))
                SET(sc->sc_hwflags, COM_HW_CONSOLE);

        if (aa->aa_offset == WINDERMERE_COM0_OFFSET)
                SET(sc->sc_flags, WMCOM_IRDA);

        sc->sc_tty = tty_alloc();
        sc->sc_tty->t_oproc = wmcom_start;
        sc->sc_tty->t_param = wmcom_param;
        sc->sc_tty->t_hwiflow = wmcom_hwiflow;

        sc->sc_tbc = 0;
        sc->sc_rbuf = malloc(WMCOM_RING_SIZE << 1, M_DEVBUF, M_WAITOK);
        sc->sc_rbput = sc->sc_rbget = sc->sc_rbuf;
        sc->sc_rbavail = WMCOM_RING_SIZE;

        tty_attach(sc->sc_tty);

        if (ISSET(sc->sc_hwflags, COM_HW_CONSOLE)) {
                int maj = cdevsw_lookup_major(&wmcom_cdevsw);

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

                aprint_normal_dev(self, "console\n");
        }

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

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

        SET(sc->sc_hwflags, COM_HW_DEV_OK);
}

static int
wmcom_intr(void *arg)
{
        struct wmcom_softc *sc = arg;
        bus_space_tag_t iot = sc->sc_iot;
        bus_space_handle_t ioh = sc->sc_ioh;
        int cc;
        uint32_t data;
        uint8_t fr, intm;
        u_char *put;

        if (!device_is_active(sc->sc_dev))
                return 0;

        fr = bus_space_read_1(iot, ioh, UARTFR);
        intm = bus_space_read_1(iot, ioh, UARTINTM);
        if (bus_space_read_1(iot, ioh, UARTINT) & INT_RXINT) {
                put = sc->sc_rbput;
                cc = sc->sc_rbavail;
                while (cc > 0) {
                        if (ISSET(fr, FR_RXFE))
                                break;
                        data = bus_space_read_4(iot, ioh, UARTDR);
                        cn_check_magic(sc->sc_tty->t_dev, data & 0xff,
                            wmcom_cnm_state);

                        put[0] = data & 0xff;
                        put[1] = (data >> 8) & 0xff;
                        put += 2;
                        if (put >= sc->sc_rbuf + (WMCOM_RING_SIZE << 1))
                                put = sc->sc_rbuf;
                        cc--;
                        sc->sc_rx_ready = 1;

                        fr = bus_space_read_1(iot, ioh, UARTFR);
                }

                /*
                 * 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;

                /*
                 * See if we are in danger of overflowing a buffer. If
                 * so, use hardware flow control to ease the pressure.
                 */

                /* but wmcom cannot. X-( */

                /*
                 * If we're out of space, disable receive interrupts
                 * until the queue has drained a bit.
                 */
                if (cc <= 0)
                        CLR(intm, INT_RXINT);
        }

        /*
         * 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(fr, FR_TXFF)) {
                /* Output the next chunk of the contiguous buffer, if any. */
                if (sc->sc_tbc > 0) {
                        while (sc->sc_tbc > 0 && !ISSET(fr, FR_TXFF)) {
                                bus_space_write_1(iot, ioh, UARTDR,
                                    *sc->sc_tba);
                                sc->sc_tba++;
                                sc->sc_tbc--;
                                fr = bus_space_read_1(iot, ioh, UARTFR);
                        }
                } else if (!ISSET(fr, FR_BUSY) && ISSET(intm, INT_TXINT)) {
                        CLR(intm, INT_TXINT);
                        sc->sc_tx_done = 1;
                }
        }

        bus_space_write_1(iot, ioh, UARTINTM, intm);

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

        return 1;
}

static void
wmcom_soft(void *arg)
{
        struct wmcom_softc *sc = arg;
        struct tty *tp = sc->sc_tty;

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

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

static void
wmcom_start(struct tty *tp)
{
        struct wmcom_softc *sc
                = device_lookup_private(&wmcom_cd, COMUNIT(tp->t_dev));
        bus_space_tag_t iot = sc->sc_iot;
        bus_space_handle_t ioh = sc->sc_ioh;
        int s, n;
        uint8_t intm;

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

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

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

        SET(tp->t_state, TS_BUSY);

        intm = bus_space_read_1(iot, ioh, UARTINTM);
        if (!ISSET(intm, INT_TXINT)) {
                bus_space_write_1(iot, ioh, UARTINTM, intm | INT_TXINT);

                /* Output the first chunk of the contiguous buffer. */
                n = uimin(sc->sc_tbc, UART_FIFO_SIZE);
                bus_space_write_multi_1(iot, ioh, UARTDR, sc->sc_tba, n);
                sc->sc_tba += n;
                sc->sc_tbc -= n;
        }
out:
        splx(s);
        return;
}

static int
wmcom_param(struct tty *tp, struct termios *t)
{
        struct wmcom_softc *sc =
            device_lookup_private(&wmcom_cd, COMUNIT(tp->t_dev));
        bus_space_tag_t iot = sc->sc_iot;
        bus_space_handle_t ioh = sc->sc_ioh;
        int s;

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

        s = splserial();
        bus_space_write_4(iot, ioh, UARTLCR, wmcom_rate2lcr(t->c_ospeed));
        bus_space_write_1(iot, ioh, UARTFCR, wmcom_cflag2fcr(t->c_cflag));

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

        /*
         * Update the tty layer's idea of the carrier bit.
         * We tell tty the carrier is always on.
         */
        (*tp->t_linesw->l_modem)(tp, 1);

        return 0;
}

static int
wmcom_hwiflow(struct tty *tp, int block)
{
        /* Nothing */
        return 0;
}

/* ARGSUSED */
int
wmcomopen(dev_t dev, int flag, int mode, struct lwp *l)
{
        struct wmcom_softc *sc;
        struct tty *tp;
        int error, s, s2;
        uint8_t con;

        sc = device_lookup_private(&wmcom_cd, COMUNIT(dev));
        if (sc == NULL || !ISSET(sc->sc_hwflags, COM_HW_DEV_OK))
                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, COM_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;

                /* Enable and turn on interrupt */
                con = CON_UARTEN;
                if (ISSET(sc->sc_flags, WMCOM_IRDA))
                        con |= CON_IRTXM;
                bus_space_write_1(sc->sc_iot, sc->sc_ioh, UARTCON, con);
                bus_space_write_1(sc->sc_iot, sc->sc_ioh, UARTINTM, INT_RXINT);

                /*
                 * Initialize the termios status to the defaults.  Add in the
                 * sticky bits from TIOCSFLAGS.
                 */
                t.c_ispeed = 0;
                if (ISSET(sc->sc_hwflags, COM_HW_CONSOLE)) {
                        t.c_ospeed = wmcom_cnrate;
                        t.c_cflag = wmcom_cncflag;
                } 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 wmcom_param() we do something */
                tp->t_ospeed = 0;
                wmcom_param(tp, &t);
                tp->t_iflag = TTYDEF_IFLAG;
                tp->t_oflag = TTYDEF_OFLAG;
                tp->t_lflag = TTYDEF_LFLAG;
                ttychars(tp);
                ttsetwater(tp);

                s2 = splserial();

                /* Clear the input ring. */
                sc->sc_rbput = sc->sc_rbget = sc->sc_rbuf;
                sc->sc_rbavail = WMCOM_RING_SIZE;
                wmcom_iflush(sc);

                splx(s2);
        }

        splx(s);

        error = ttyopen(tp, COMDIALOUT(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.
                 */
                wmcom_shutdown(sc);

                /* Disable UART */
                if (!ISSET(sc->sc_hwflags, COM_HW_CONSOLE))
                        bus_space_write_1(sc->sc_iot, sc->sc_ioh, UARTCON, 0);
        }

        return error;
}

/* ARGSUSED */
int
wmcomclose(dev_t dev, int flag, int mode, struct lwp *l)
{
        struct wmcom_softc *sc = device_lookup_private(&wmcom_cd, COMUNIT(dev));
        struct tty *tp = sc->sc_tty;

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

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

        if (!device_is_active(sc->sc_dev))
                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.
                 */
                wmcom_shutdown(sc);

                /* Disable UART */
                if (!ISSET(sc->sc_hwflags, COM_HW_CONSOLE))
                        bus_space_write_1(sc->sc_iot, sc->sc_ioh, UARTCON, 0);
        }

        return 0;
}

int
wmcomread(dev_t dev, struct uio *uio, int flag)
{
        struct wmcom_softc *sc = device_lookup_private(&wmcom_cd, COMUNIT(dev));
        struct tty *tp = sc->sc_tty;

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

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

int
wmcomwrite(dev_t dev, struct uio *uio, int flag)
{
        struct wmcom_softc *sc = device_lookup_private(&wmcom_cd, COMUNIT(dev));
        struct tty *tp = sc->sc_tty;

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

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

int
wmcomioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
{
        struct wmcom_softc *sc = device_lookup_private(&wmcom_cd, COMUNIT(dev));
        struct tty *tp = sc->sc_tty;
        int error, s;

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

        switch (cmd) {
        case TIOCSFLAGS:
                error = kauth_authorize_device_tty(l->l_cred,
                    KAUTH_DEVICE_TTY_PRIVSET, tp);
                break;
        default:
                break;
        }
        if (error)
                return error;

        s = splserial();
        error = 0;
        switch (cmd) {
        case TIOCSBRK:
                wmcom_break(sc, 1);
                break;

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

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

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

        default:
                error = EPASSTHROUGH;
                break;
        }
        splx(s);
        return error;
}

int
wmcompoll(dev_t dev, int events, struct lwp *l)
{
        struct wmcom_softc *sc = device_lookup_private(&wmcom_cd, COMUNIT(dev));
        struct tty *tp = sc->sc_tty;

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

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

struct tty *
wmcomtty(dev_t dev)
{
        struct wmcom_softc *sc = device_lookup_private(&wmcom_cd, COMUNIT(dev));

        return sc->sc_tty;
}

void
wmcomstop(struct tty *tp, int flag)
{
        int s;

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


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

        timo = 50000;
        while ((bus_space_read_1(iot, ioh, UARTFR) & FR_RXFE) == 0 &&
            timo--)
                bus_space_read_1(iot, ioh, UARTDR);
        if (timo == 0)
                printf("%s: iflush timeout\n", device_xname(sc->sc_dev));
}

static void
wmcom_shutdown(struct wmcom_softc *sc)
{
        int s;

        s = splserial();

        /* Turn off interrupt */
        bus_space_write_1(sc->sc_iot, sc->sc_ioh, UARTINTM, 0);

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

        splx(s);
}

static void
wmcom_break(struct wmcom_softc *sc, int onoff)
{
        int s;
        uint8_t fcr;

        s = splserial();
        fcr = bus_space_read_1(sc->sc_iot, sc->sc_ioh, UARTFCR);
        if (onoff)
                SET(fcr, FCR_BREAK);
        else
                CLR(fcr, FCR_BREAK);
        bus_space_write_1(sc->sc_iot, sc->sc_ioh, UARTFCR, fcr);
        splx(s);
}

static void
wmcom_rxsoft(struct wmcom_softc *sc, struct tty *tp)
{
        bus_space_tag_t iot = sc->sc_iot;
        bus_space_handle_t ioh = sc->sc_ioh;
        int code, s;
        u_int cc, scc;
        uint8_t intm;
        u_char sts, *get;

        get = sc->sc_rbget;
        scc = cc = WMCOM_RING_SIZE - sc->sc_rbavail;
        while (cc) {
                code = get[0];
                sts = get[1];
                if (ISSET(sts, RSR_FE | RSR_PE | RSR_OE)) {
                        if (ISSET(sts, (RSR_FE)))
                                SET(code, TTY_FE);
                        if (ISSET(sts, RSR_PE))
                                SET(code, TTY_PE);
                        if (ISSET(sts, RSR_OE))
                                ;               /* XXXXX: Overrun */
                }
                if ((*tp->t_linesw->l_rint)(code, tp) == -1) {
                        /*
                         * The line discipline's buffer is out of space.
                         */
                        /*
                         * 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 >= sc->sc_rbuf + (WMCOM_RING_SIZE << 1))
                                get -= (WMCOM_RING_SIZE << 1);
                        cc = 0;
                        break;
                }
                get += 2;
                if (get >= sc->sc_rbuf + (WMCOM_RING_SIZE << 1))
                        get = sc->sc_rbuf;
                cc--;
        }

        if (cc != scc) {
                sc->sc_rbget = get;
                s = splserial();
                
                cc = sc->sc_rbavail += scc - cc;
                /* Buffers should be ok again, release possible block. */
                if (cc >= 1) {
                        intm = bus_space_read_1(iot, ioh, UARTINTM);
                        SET(intm, INT_RXINT);
                        bus_space_write_1(iot, ioh, UARTINTM, intm);
                }
                splx(s);
        }
}

static inline uint32_t
wmcom_rate2lcr(int rate)
{

        return 7372800 / (16 * rate) - 1;
}

static uint8_t
wmcom_cflag2fcr(tcflag_t cflag)
{
        int8_t fcr = FCR_UFIFOEN;

        switch (cflag & CSIZE) {
        case CS5: SET(fcr, FCR_WLEN_5); break;
        case CS6: SET(fcr, FCR_WLEN_6); break;
        case CS7: SET(fcr, FCR_WLEN_7); break;
        case CS8: SET(fcr, FCR_WLEN_8); break;
        default:  SET(fcr, FCR_WLEN_8); break;
        }
        if (cflag & CSTOPB)
                SET(fcr, FCR_XSTOP);
        if (cflag & PARENB) {
                SET(fcr, (FCR_PRTEN | FCR_EVENPRT));
                if (cflag & PARODD)
                        CLR(fcr, FCR_EVENPRT);
        }
        return fcr;
}

#define WMCOM_CNREAD_1(offset) \
        (*(volatile uint8_t *)(wmcom_cnaddr + ((offset) << 2)))
#define WMCOM_CNREAD_4(offset) \
        (*(volatile uint32_t *)(wmcom_cnaddr + ((offset) << 2)))
#define WMCOM_CNWRITE_1(offset, val) \
        (*(volatile uint8_t *)(wmcom_cnaddr + ((offset) << 2)) = val)
#define WMCOM_CNWRITE_4(offset, val) \
        (*(volatile uint32_t *)(wmcom_cnaddr + ((offset) << 2)) = val)

static struct consdev wmcomcons = {
        NULL, NULL, wmcom_cngetc, wmcom_cnputc, wmcom_cnpollc, NULL, NULL, NULL,
        NODEV, CN_NORMAL
};

int
wmcom_cnattach(vaddr_t addr, int rate, tcflag_t cflag, int irda)
{

        wmcom_cnaddr = addr;
        wmcom_cnrate = rate;
        wmcom_cncflag = cflag;
        WMCOM_CNWRITE_4(UARTLCR, wmcom_rate2lcr(rate));
        WMCOM_CNWRITE_1(UARTFCR, wmcom_cflag2fcr(cflag));
        if (irda)
                WMCOM_CNWRITE_1(UARTCON, CON_UARTEN | CON_IRTXM);
        else
                WMCOM_CNWRITE_1(UARTCON, CON_UARTEN);

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

        return 0;
}

/* ARGSUSED */
static int
wmcom_cngetc(dev_t dev)
{
        int s = splserial();
        char ch;

        while (WMCOM_CNREAD_1(UARTFR) & FR_RXFE);

        ch = WMCOM_CNREAD_4(UARTDR);

        {
                if (!db_active)
                        cn_check_magic(dev, ch, wmcom_cnm_state);
        }

        splx(s);
        return ch;
}

/* ARGSUSED */
static void
wmcom_cnputc(dev_t dev, int c)
{
        int s = splserial();

        while (WMCOM_CNREAD_1(UARTFR) & FR_TXFF);

        WMCOM_CNWRITE_1(UARTDR, c);

        /* Make sure output. */
        while (WMCOM_CNREAD_1(UARTFR) & FR_BUSY);

        splx(s);
}

/* ARGSUSED */
static void
wmcom_cnpollc(dev_t dev, int on)
{
        /* Nothing */
}