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[netbsd-mini2440.git] / sys / arch / arm / ep93xx / epcom.c

/*      $NetBSD: epcom.c,v 1.18 2008/06/11 22:37:21 cegger Exp $ */
/*
 * Copyright (c) 1998, 1999, 2001, 2002, 2004 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Jesse Off
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Ichiro FUKUHARA and Naoto Shimazaki.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by IWAMOTO Toshihiro.
 *
 * 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
 */

/*
 * TODO: hardware flow control
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: epcom.c,v 1.18 2008/06/11 22:37:21 cegger Exp $");

#include "opt_ddb.h"
#include "opt_kgdb.h"
#include "epcom.h"

#include "rnd.h"
#if NRND > 0 && defined(RND_COM)
#include <sys/rnd.h>
#endif

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


#include <sys/param.h>
#include <sys/systm.h>
#include <sys/types.h>
#include <sys/conf.h>
#include <sys/file.h>
#include <sys/device.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/tty.h>
#include <sys/uio.h>
#include <sys/vnode.h>
#include <sys/kauth.h>

#include <machine/intr.h>
#include <machine/bus.h>

#include <arm/ep93xx/epcomreg.h>
#include <arm/ep93xx/epcomvar.h>
#include <arm/ep93xx/ep93xxreg.h>
#include <arm/ep93xx/ep93xxvar.h>

#include <dev/cons.h>

static int      epcomparam(struct tty *, struct termios *);
static void     epcomstart(struct tty *);
static int      epcomhwiflow(struct tty *, int);

static u_int    cflag2lcrhi(tcflag_t);
static void     epcom_iflush(struct epcom_softc *);
static void     epcom_set(struct epcom_softc *);

int             epcomcngetc(dev_t);
void            epcomcnputc(dev_t, int);
void            epcomcnpollc(dev_t, int);

static void     epcomsoft(void* arg);
inline static void      epcom_txsoft(struct epcom_softc *, struct tty *);
inline static void      epcom_rxsoft(struct epcom_softc *, struct tty *);

void            epcomcnprobe(struct consdev *);
void            epcomcninit(struct consdev *);

static struct epcom_cons_softc {
        bus_space_tag_t         sc_iot;
        bus_space_handle_t      sc_ioh;
        bus_addr_t              sc_hwbase;
        int                     sc_ospeed;
        tcflag_t                sc_cflag;
        int                     sc_attached;
} epcomcn_sc;

static struct cnm_state epcom_cnm_state;

extern struct cfdriver epcom_cd;

dev_type_open(epcomopen);
dev_type_close(epcomclose);
dev_type_read(epcomread);
dev_type_write(epcomwrite);
dev_type_ioctl(epcomioctl);
dev_type_stop(epcomstop);
dev_type_tty(epcomtty);
dev_type_poll(epcompoll);

const struct cdevsw epcom_cdevsw = {
        epcomopen, epcomclose, epcomread, epcomwrite, epcomioctl,
        epcomstop, epcomtty, epcompoll, nommap, ttykqfilter, D_TTY
};

struct consdev epcomcons = {
        NULL, NULL, epcomcngetc, epcomcnputc, epcomcnpollc, NULL,
        NULL, NULL, NODEV, CN_NORMAL
};

#ifndef DEFAULT_COMSPEED
#define DEFAULT_COMSPEED 115200
#endif

#define COMUNIT_MASK    0x7ffff
#define COMDIALOUT_MASK 0x80000

#define COMUNIT(x)      (minor(x) & COMUNIT_MASK)
#define COMDIALOUT(x)   (minor(x) & COMDIALOUT_MASK)

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

void
epcom_attach_subr(struct epcom_softc *sc)
{
        struct tty *tp;

        if (sc->sc_iot == epcomcn_sc.sc_iot
            && sc->sc_hwbase == epcomcn_sc.sc_hwbase) {
                epcomcn_sc.sc_attached = 1;
                sc->sc_lcrlo = EPCOMSPEED2BRD(epcomcn_sc.sc_ospeed) & 0xff;
                sc->sc_lcrmid = EPCOMSPEED2BRD(epcomcn_sc.sc_ospeed) >> 8;

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

        tp = ttymalloc();
        tp->t_oproc = epcomstart;
        tp->t_param = epcomparam;
        tp->t_hwiflow = epcomhwiflow;

        sc->sc_tty = tp;
        sc->sc_rbuf = malloc(EPCOM_RING_SIZE << 1, M_DEVBUF, M_NOWAIT);
        sc->sc_rbput = sc->sc_rbget = sc->sc_rbuf;
        sc->sc_rbavail = EPCOM_RING_SIZE;
        if (sc->sc_rbuf == NULL) {
                printf("%s: unable to allocate ring buffer\n",
                    sc->sc_dev.dv_xname);
                return;
        }
        sc->sc_ebuf = sc->sc_rbuf + (EPCOM_RING_SIZE << 1);
        sc->sc_tbc = 0;

        sc->sc_lcrlo = EPCOMSPEED2BRD(DEFAULT_COMSPEED) & 0xff;
        sc->sc_lcrmid = EPCOMSPEED2BRD(DEFAULT_COMSPEED) >> 8;
        sc->sc_lcrhi = cflag2lcrhi(CS8); /* 8N1 */

        tty_attach(tp);

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

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

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

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

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

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

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

        /* XXX configure register */
        /* xxx_config(sc) */

        SET(sc->sc_hwflags, COM_HW_DEV_OK);
}

static int
epcomparam(struct tty *tp, struct termios *t)
{
        struct epcom_softc *sc
                = device_lookup_private(&epcom_cd, COMUNIT(tp->t_dev));
        int s;

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

        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();

        sc->sc_lcrhi = cflag2lcrhi(t->c_cflag);
        sc->sc_lcrlo = EPCOMSPEED2BRD(t->c_ospeed) & 0xff;
        sc->sc_lcrmid = EPCOMSPEED2BRD(t->c_ospeed) >> 8;
        
        /* And copy to tty. */
        tp->t_ispeed = 0;
        tp->t_ospeed = t->c_ospeed;
        tp->t_cflag = t->c_cflag;
        epcom_set(sc);

        splx(s);

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

#ifdef COM_DEBUG
        if (com_debug)
                comstatus(sc, "comparam ");
#endif

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

        return (0);
}

static int
epcomhwiflow(struct tty *tp, int block)
{
        return (0);
}

static void
epcom_filltx(struct epcom_softc *sc)
{
        bus_space_tag_t iot = sc->sc_iot;
        bus_space_handle_t ioh = sc->sc_ioh;
        int n;

        n = 0;
        while ((bus_space_read_4(iot, ioh, EPCOM_Flag) & Flag_TXFF) == 0) {
                if (n >= sc->sc_tbc)
                        break;
                bus_space_write_4(iot, ioh, EPCOM_Data,
                                  0xff & *(sc->sc_tba + n));
                n++;
        }
        sc->sc_tbc -= n;
        sc->sc_tba += n;
}

static void
epcomstart(struct tty *tp)
{
        struct epcom_softc *sc
                = device_lookup_private(&epcom_cd, COMUNIT(tp->t_dev));
        int s;

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

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

        /* Grab the first contiguous region of buffer space. */
        {
                u_char *tba;
                int tbc;

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

                (void)splserial();

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

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

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

        if (!ISSET(sc->sc_ctrl, Ctrl_TIE)) {
                SET(sc->sc_ctrl, Ctrl_TIE);
                epcom_set(sc);
        }

out:
        splx(s);
        return;
}

static void
epcom_break(struct epcom_softc *sc, int onoff)
{
        if (onoff)
                SET(sc->sc_lcrhi, LinCtrlHigh_BRK);
        else
                CLR(sc->sc_lcrhi, LinCtrlHigh_BRK);
        epcom_set(sc);
}

static void
epcom_shutdown(struct epcom_softc *sc)
{
        int s;

        s = splserial();

        /* Turn off interrupts. */
        CLR(sc->sc_ctrl, (Ctrl_TIE|Ctrl_RTIE|Ctrl_RIE));

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

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

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

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

                s2 = splserial();

                if (sc->enable) {
                        if ((*sc->enable)(sc)) {
                                splx(s2);
                                splx(s);
                                printf("%s: device enable failed\n",
                                       sc->sc_dev.dv_xname);
                                return (EIO);
                        }
                        sc->enabled = 1;
#if 0
/* XXXXXXXXXXXXXXX */
                        com_config(sc);
#endif
                }

                /* Turn on interrupts. */
                SET(sc->sc_ctrl, (Ctrl_UARTE|Ctrl_RIE|Ctrl_RTIE));
                epcom_set(sc);

#if 0
                /* Fetch the current modem control status, needed later. */
                sc->sc_msr = bus_space_read_1(sc->sc_iot, sc->sc_ioh, com_msr);

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

                splx(s2);

                /*
                 * Initialize the termios status to the defaults.  Add in the
                 * sticky bits from TIOCSFLAGS.
                 */
                t.c_ispeed = 0;
                if (ISSET(sc->sc_hwflags, COM_HW_CONSOLE)) {
                        t.c_ospeed = epcomcn_sc.sc_ospeed;
                        t.c_cflag = epcomcn_sc.sc_cflag;
                } 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 epcomparam() will do something. */
                tp->t_ospeed = 0;
                (void) epcomparam(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, and unblock. */
                sc->sc_rbput = sc->sc_rbget = sc->sc_rbuf;
                sc->sc_rbavail = EPCOM_RING_SIZE;
                epcom_iflush(sc);
                CLR(sc->sc_rx_flags, RX_ANY_BLOCK);

#ifdef COM_DEBUG
                if (epcom_debug)
                        comstatus(sc, "epcomopen  ");
#endif

                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.
                 */
                epcom_shutdown(sc);
        }

        return (error);
}

int
epcomclose(dev_t dev, int flag, int mode, struct lwp *l)
{
        struct epcom_softc *sc = device_lookup_private(&epcom_cd, COMUNIT(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 (COM_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.
                 */
                epcom_shutdown(sc);
        }

        return (0);
}

int
epcomread(dev_t dev, struct uio *uio, int flag)
{
        struct epcom_softc *sc = device_lookup_private(&epcom_cd, COMUNIT(dev));
        struct tty *tp = sc->sc_tty;

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

int
epcomwrite(dev_t dev, struct uio *uio, int flag)
{
        struct epcom_softc *sc = device_lookup_private(&epcom_cd, COMUNIT(dev));
        struct tty *tp = sc->sc_tty;

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

int
epcompoll(dev_t dev, int events, struct lwp *l)
{
        struct epcom_softc *sc = device_lookup_private(&epcom_cd, COMUNIT(dev));
        struct tty *tp = sc->sc_tty;

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

struct tty *
epcomtty(dev_t dev)
{
        struct epcom_softc *sc = device_lookup_private(&epcom_cd, COMUNIT(dev));
        struct tty *tp = sc->sc_tty;

        return (tp);
}

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

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

        error = (*tp->t_linesw->l_ioctl)(tp, cmd, data, flag, l);
        if (error != EPASSTHROUGH)
                return (error);

        error = ttioctl(tp, cmd, data, flag, l);
        if (error != EPASSTHROUGH)
                return (error);

        error = 0;

        s = splserial();

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

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

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

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

        default:
                error = EPASSTHROUGH;
                break;
        }

        splx(s);

        return (error);
}

/*
 * Stop output on a line.
 */
void
epcomstop(struct tty *tp, int flag)
{
        struct epcom_softc *sc
                = device_lookup_private(&epcom_cd, COMUNIT(tp->t_dev));
        int s;

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

static u_int
cflag2lcrhi(tcflag_t cflag)
{
        u_int lcrhi;

        switch (cflag & CSIZE) {
        case CS7:
                lcrhi = 0x40;
                break;
        case CS6:
                lcrhi = 0x20;
                break;
        case CS8:
        default:
                lcrhi = 0x60;
                break;
        }
        lcrhi |= (cflag & PARENB) ? LinCtrlHigh_PEN : 0;
        lcrhi |= (cflag & PARODD) ? 0 : LinCtrlHigh_EPS;
        lcrhi |= (cflag & CSTOPB) ? LinCtrlHigh_STP2 : 0;
        lcrhi |= LinCtrlHigh_FEN;  /* FIFO always enabled */
        
        return (lcrhi);
}

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

#ifdef DIAGNOSTIC
        reg = 0xffff;
#endif
        timo = 50000;
        /* flush any pending I/O */
        while ((bus_space_read_4(iot, ioh, EPCOM_Flag) & Flag_RXFE) == 0
               && --timo)
#ifdef DIAGNOSTIC
                reg =
#else
                        (void)
#endif
                        bus_space_read_4(iot, ioh, EPCOM_Data);
#ifdef DIAGNOSTIC
        if (!timo)
                printf("%s: com_iflush timeout %02x\n", sc->sc_dev.dv_xname,
                       reg);
#endif
}

static void
epcom_set(struct epcom_softc *sc)
{
        bus_space_write_4(sc->sc_iot, sc->sc_ioh, EPCOM_LinCtrlLow,
                          sc->sc_lcrlo);
        bus_space_write_4(sc->sc_iot, sc->sc_ioh, EPCOM_LinCtrlMid,
                          sc->sc_lcrmid);
        bus_space_write_4(sc->sc_iot, sc->sc_ioh, EPCOM_LinCtrlHigh,
                          sc->sc_lcrhi);
        bus_space_write_4(sc->sc_iot, sc->sc_ioh, EPCOM_Ctrl,
                          sc->sc_ctrl);
}

int
epcomcnattach(bus_space_tag_t iot, bus_addr_t iobase, bus_space_handle_t ioh,
    int ospeed, tcflag_t cflag)
{
        u_int lcrlo, lcrmid, lcrhi, ctrl, pwrcnt;
        bus_space_handle_t syscon_ioh;

        cn_tab = &epcomcons;
        cn_init_magic(&epcom_cnm_state);
        cn_set_magic("\047\001");

        epcomcn_sc.sc_iot = iot;
        epcomcn_sc.sc_ioh = ioh;
        epcomcn_sc.sc_hwbase = iobase;
        epcomcn_sc.sc_ospeed = ospeed;
        epcomcn_sc.sc_cflag = cflag;

        lcrhi = cflag2lcrhi(cflag);
        lcrlo = EPCOMSPEED2BRD(ospeed) & 0xff;
        lcrmid = EPCOMSPEED2BRD(ospeed) >> 8;
        ctrl = Ctrl_UARTE;

        bus_space_map(iot, EP93XX_APB_HWBASE + EP93XX_APB_SYSCON,
                EP93XX_APB_SYSCON_SIZE, 0, &syscon_ioh);
        pwrcnt = bus_space_read_4(iot, syscon_ioh, EP93XX_SYSCON_PwrCnt);
        pwrcnt &= ~(PwrCnt_UARTBAUD);
        bus_space_write_4(iot, syscon_ioh, EP93XX_SYSCON_PwrCnt, pwrcnt);
        bus_space_unmap(iot, syscon_ioh, EP93XX_APB_SYSCON_SIZE);

        bus_space_write_4(iot, ioh, EPCOM_LinCtrlLow, lcrlo);
        bus_space_write_4(iot, ioh, EPCOM_LinCtrlMid, lcrmid);
        bus_space_write_4(iot, ioh, EPCOM_LinCtrlHigh, lcrhi);
        bus_space_write_4(iot, ioh, EPCOM_Ctrl, ctrl);

        return (0);
}

void
epcomcnprobe(struct consdev *cp)
{
        cp->cn_pri = CN_REMOTE;
}

void
epcomcnpollc(dev_t dev, int on)
{
}

void
epcomcnputc(dev_t dev, int c)
{
        int                     s;
        bus_space_tag_t         iot = epcomcn_sc.sc_iot;
        bus_space_handle_t      ioh = epcomcn_sc.sc_ioh;

        s = splserial();

        while((bus_space_read_4(iot, ioh, EPCOM_Flag) & Flag_TXFF) != 0)
                ;

        bus_space_write_4(iot, ioh, EPCOM_Data, c);

#ifdef DEBUG
        if (c == '\r') {
                while((bus_space_read_4(iot, ioh, EPCOM_Flag) & Flag_TXFE) == 0)
                        ;
        }
#endif

        splx(s);
}

int
epcomcngetc(dev_t dev)
{
        int                     c, sts;
        int                     s;
        bus_space_tag_t         iot = epcomcn_sc.sc_iot;
        bus_space_handle_t      ioh = epcomcn_sc.sc_ioh;

        s = splserial();

        while((bus_space_read_4(iot, ioh, EPCOM_Flag) & Flag_RXFE) != 0)
                ;

        c = bus_space_read_4(iot, ioh, EPCOM_Data);
        sts = bus_space_read_4(iot, ioh, EPCOM_RXSts);
        if (ISSET(sts, RXSts_BE)) c = CNC_BREAK;
#ifdef DDB
        extern int db_active;
        if (!db_active)
#endif
        {
                int cn_trapped = 0; /* unused */

                cn_check_magic(dev, c, epcom_cnm_state);
        }
        c &= 0xff;
        splx(s);

        return (c);
}

inline static void
epcom_txsoft(struct epcom_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);
}

inline static void
epcom_rxsoft(struct epcom_softc *sc, struct tty *tp)
{
        int (*rint)(int, struct tty *) = tp->t_linesw->l_rint;
        u_char *get, *end;
        u_int cc, scc;
        u_char sts;
        int code;
        int s;

        end = sc->sc_ebuf;
        get = sc->sc_rbget;
        scc = cc = EPCOM_RING_SIZE - sc->sc_rbavail;
#if 0
        if (cc == EPCOM_RING_SIZE) {
                sc->sc_floods++;
                if (sc->sc_errors++ == 0)
                        callout_reset(&sc->sc_diag_callout, 60 * hz,
                            comdiag, sc);
        }
#endif
        while (cc) {
                code = get[0];
                sts = get[1];
                if (ISSET(sts, RXSts_OE | RXSts_FE | RXSts_PE | RXSts_BE)) {
#if 0
                        if (ISSET(lsr, DR_ROR)) {
                                sc->sc_overflows++;
                                if (sc->sc_errors++ == 0)
                                        callout_reset(&sc->sc_diag_callout,
                                            60 * hz, comdiag, sc);
                        }
#endif
                        if (ISSET(sts, (RXSts_FE|RXSts_BE)))
                                SET(code, TTY_FE);
                        if (ISSET(sts, RXSts_PE))
                                SET(code, TTY_PE);
                }
                if ((*rint)(code, tp) == -1) {
                        /*
                         * The line discipline's buffer is out of space.
                         */
                        if (!ISSET(sc->sc_rx_flags, RX_TTY_BLOCKED)) {
                                /*
                                 * We're either not using flow control, or the
                                 * line discipline didn't tell us to block for
                                 * some reason.  Either way, we have no way to
                                 * know when there's more space available, so
                                 * just drop the rest of the data.
                                 */
                                get += cc << 1;
                                if (get >= end)
                                        get -= EPCOM_RING_SIZE << 1;
                                cc = 0;
                        } else {
                                /*
                                 * Don't schedule any more receive processing
                                 * until the line discipline tells us there's
                                 * space available (through comhwiflow()).
                                 * Leave the rest of the data in the input
                                 * buffer.
                                 */
                                SET(sc->sc_rx_flags, RX_TTY_OVERFLOWED);
                        }
                        break;
                }
                get += 2;
                if (get >= end)
                        get = sc->sc_rbuf;
                cc--;
        }

        if (cc != scc) {
                sc->sc_rbget = get;
                s = splserial();
                
                cc = sc->sc_rbavail += scc - cc;
                /* Buffers should be ok again, release possible block. */
                if (cc >= 1) {
                        if (ISSET(sc->sc_rx_flags, RX_IBUF_OVERFLOWED)) {
                                CLR(sc->sc_rx_flags, RX_IBUF_OVERFLOWED);
                                SET(sc->sc_ctrl, (Ctrl_RIE|Ctrl_RTIE));
                                epcom_set(sc);
                        }
                        if (ISSET(sc->sc_rx_flags, RX_IBUF_BLOCKED)) {
                                CLR(sc->sc_rx_flags, RX_IBUF_BLOCKED);
#if 0
                                com_hwiflow(sc);
#endif
                        }
                }
                splx(s);
        }
}

static void
epcomsoft(void* arg)
{
        struct epcom_softc *sc = arg;

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

        if (sc->sc_rx_ready) {
                sc->sc_rx_ready = 0;
                epcom_rxsoft(sc, sc->sc_tty);
        }
        if (sc->sc_tx_done) {
                sc->sc_tx_done = 0;
                epcom_txsoft(sc, sc->sc_tty);
        }
}

int
epcomintr(void* arg)
{
        struct epcom_softc *sc = arg;
        bus_space_tag_t iot = sc->sc_iot;
        bus_space_handle_t ioh = sc->sc_ioh;
        u_char *put, *end;
        u_int cc;
        u_int flagr;
        u_int intr;
        u_int32_t c, csts;

        intr = bus_space_read_4(iot, ioh, EPCOM_IntIDIntClr);

        if (COM_ISALIVE(sc) == 0) 
                panic("intr on disabled epcom");

        flagr = bus_space_read_4(iot, ioh, EPCOM_Flag);

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

        if (!(ISSET(flagr, Flag_RXFE))) {
                if (!ISSET(sc->sc_rx_flags, RX_IBUF_OVERFLOWED)) {
                        while (cc > 0) {
                                if (ISSET(flagr, Flag_RXFE))
                                        break;
                                c = bus_space_read_4(iot, ioh, EPCOM_Data);
                                csts = bus_space_read_4(iot, ioh, EPCOM_RXSts);
                                if (ISSET(csts, RXSts_BE)) {
                                        int cn_trapped = 0;

                                        cn_check_magic(sc->sc_tty->t_dev,
                                          CNC_BREAK, epcom_cnm_state);
                                        if (cn_trapped)
                                                goto next;
#if defined(KGDB) && !defined(DDB)
                                        if (ISSET(sc->sc_hwflags, COM_HW_KGDB)){
                                                kgdb_connect(1);
                                                goto next;
                                        }
#endif
                                } else {
                                        int cn_trapped = 0;

                                        cn_check_magic(sc->sc_tty->t_dev,
                                          (c & 0xff), epcom_cnm_state);
                                        if (cn_trapped)
                                                goto next;
                                }


                                put[0] = c & 0xff;
                                put[1] = csts & 0xf;
                                put += 2;
                                if (put >= end)
                                        put = sc->sc_rbuf;
                                cc--;
                        next:
                                flagr = bus_space_read_4(iot, ioh, EPCOM_Flag);
                        }

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

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

                        /* but epcom cannot. X-( */

                        /*
                         * If we're out of space, disable receive interrupts
                         * until the queue has drained a bit.
                         */
                        if (!cc) {
                                SET(sc->sc_rx_flags, RX_IBUF_OVERFLOWED);
                                CLR(sc->sc_ctrl, (Ctrl_RIE|Ctrl_RTIE));
                                epcom_set(sc);
                        }
                } else {
#ifdef DIAGNOSTIC
                        panic("epcomintr: we shouldn't reach here");
#endif
                        CLR(sc->sc_ctrl, (Ctrl_RIE|Ctrl_RTIE));
                        epcom_set(sc);
                }
        }

        /*
         * 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(flagr, Flag_TXFF) && sc->sc_tbc > 0) {
                /* Output the next chunk of the contiguous buffer, if any. */
                epcom_filltx(sc);
        } else {
                /* Disable transmit completion interrupts if necessary. */
                if (ISSET(sc->sc_ctrl, Ctrl_TIE)) {
                        CLR(sc->sc_ctrl, Ctrl_TIE);
                        epcom_set(sc);
                }
                if (sc->sc_tx_busy) {
                        sc->sc_tx_busy = 0;
                        sc->sc_tx_done = 1;
                }
        }

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

#if 0 /* XXX: broken */
#if NRND > 0 && defined(RND_COM)
        rnd_add_uint32(&sc->rnd_source, intr ^ flagr);
#endif
#endif
        return (1);
}