Expand PMF_FN_* macros.

[netbsd-mini2440.git] / sys / dev / ic / com.c

/* $NetBSD: com.c,v 1.292 2009/12/06 23:15:59 dyoung Exp $ */

/*-
 * 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
 */

/*
 * COM driver, uses National Semiconductor NS16450/NS16550AF UART
 * Supports automatic hardware flow control on StarTech ST16C650A UART
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: com.c,v 1.292 2009/12/06 23:15:59 dyoung Exp $");

#include "opt_com.h"
#include "opt_ddb.h"
#include "opt_kgdb.h"
#include "opt_lockdebug.h"
#include "opt_multiprocessor.h"
#include "opt_ntp.h"

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

/* The COM16650 option was renamed to COM_16650. */
#ifdef COM16650
#error Obsolete COM16650 option; use COM_16650 instead.
#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/malloc.h>
#include <sys/timepps.h>
#include <sys/vnode.h>
#include <sys/kauth.h>
#include <sys/intr.h>

#include <sys/bus.h>

#include <dev/ic/comreg.h>
#include <dev/ic/comvar.h>
#include <dev/ic/ns16550reg.h>
#include <dev/ic/st16650reg.h>
#ifdef COM_HAYESP
#include <dev/ic/hayespreg.h>
#endif
#define com_lcr com_cfcr
#include <dev/cons.h>

#ifdef  COM_REGMAP
#define CSR_WRITE_1(r, o, v)    \
        bus_space_write_1((r)->cr_iot, (r)->cr_ioh, (r)->cr_map[o], v)
#define CSR_READ_1(r, o)        \
        bus_space_read_1((r)->cr_iot, (r)->cr_ioh, (r)->cr_map[o])
#define CSR_WRITE_2(r, o, v)    \
        bus_space_write_2((r)->cr_iot, (r)->cr_ioh, (r)->cr_map[o], v)
#define CSR_READ_2(r, o)        \
        bus_space_read_2((r)->cr_iot, (r)->cr_ioh, (r)->cr_map[o])
#define CSR_WRITE_MULTI(r, o, p, n)     \
        bus_space_write_multi_1((r)->cr_iot, (r)->cr_ioh, (r)->cr_map[o], p, n)
#else
#define CSR_WRITE_1(r, o, v)    \
        bus_space_write_1((r)->cr_iot, (r)->cr_ioh, o, v)
#define CSR_READ_1(r, o)        \
        bus_space_read_1((r)->cr_iot, (r)->cr_ioh, o)
#define CSR_WRITE_2(r, o, v)    \
        bus_space_write_2((r)->cr_iot, (r)->cr_ioh, o, v)
#define CSR_READ_2(r, o)        \
        bus_space_read_2((r)->cr_iot, (r)->cr_ioh, o)
#define CSR_WRITE_MULTI(r, o, p, n)     \
        bus_space_write_multi_1((r)->cr_iot, (r)->cr_ioh, o, p, n)
#endif


static void com_enable_debugport(struct com_softc *);

void    com_config(struct com_softc *);
void    com_shutdown(struct com_softc *);
int     comspeed(long, long, int);
static  u_char  cflag2lcr(tcflag_t);
int     comparam(struct tty *, struct termios *);
void    comstart(struct tty *);
int     comhwiflow(struct tty *, int);

void    com_loadchannelregs(struct com_softc *);
void    com_hwiflow(struct com_softc *);
void    com_break(struct com_softc *, int);
void    com_modem(struct com_softc *, int);
void    tiocm_to_com(struct com_softc *, u_long, int);
int     com_to_tiocm(struct com_softc *);
void    com_iflush(struct com_softc *);

int     com_common_getc(dev_t, struct com_regs *);
static void     com_common_putc(dev_t, struct com_regs *, int);

int     cominit(struct com_regs *, int, int, int, tcflag_t);

static int comcnreattach(void);

int     comcngetc(dev_t);
void    comcnputc(dev_t, int);
void    comcnpollc(dev_t, int);

#define integrate       static inline
void    comsoft(void *);
integrate void com_rxsoft(struct com_softc *, struct tty *);
integrate void com_txsoft(struct com_softc *, struct tty *);
integrate void com_stsoft(struct com_softc *, struct tty *);
integrate void com_schedrx(struct com_softc *);
void    comdiag(void *);

extern struct cfdriver com_cd;

dev_type_open(comopen);
dev_type_close(comclose);
dev_type_read(comread);
dev_type_write(comwrite);
dev_type_ioctl(comioctl);
dev_type_stop(comstop);
dev_type_tty(comtty);
dev_type_poll(compoll);

static struct comcons_info comcons_info;

/*
 * Following are all routines needed for COM to act as console
 */
static struct consdev comcons = {
        NULL, NULL, comcngetc, comcnputc, comcnpollc, NULL, NULL, NULL,
        NODEV, CN_NORMAL
};


const struct cdevsw com_cdevsw = {
        comopen, comclose, comread, comwrite, comioctl,
        comstop, comtty, compoll, nommap, ttykqfilter, D_TTY
};

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

/* Stop input when 3/4 of the ring is full; restart when only 1/4 is full. */
u_int com_rbuf_hiwat = (COM_RING_SIZE * 1) / 4;
u_int com_rbuf_lowat = (COM_RING_SIZE * 3) / 4;

static int comconsattached;
static struct cnm_state com_cnm_state;

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

static struct com_regs comkgdbregs;
static int com_kgdb_attached;

int     com_kgdb_getc(void *);
void    com_kgdb_putc(void *, int);
#endif /* KGDB */

#ifdef COM_REGMAP
/* initializer for typical 16550-ish hardware */
#define COM_REG_16550   { \
        com_data, com_data, com_dlbl, com_dlbh, com_ier, com_iir, com_fifo, \
        com_efr, com_lcr, com_mcr, com_lsr, com_msr }

const bus_size_t com_std_map[16] = COM_REG_16550;
#endif /* COM_REGMAP */

#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))

#define BR      BUS_SPACE_BARRIER_READ
#define BW      BUS_SPACE_BARRIER_WRITE
#define COM_BARRIER(r, f) \
        bus_space_barrier((r)->cr_iot, (r)->cr_ioh, 0, (r)->cr_nports, (f))

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

        int x, err;
        int divisor = 16;

        if ((type == COM_TYPE_OMAP) && (speed > 230400)) {
            divisor = 13;
        }

#if 0
        if (speed == 0)
                return (0);
#endif
        if (speed <= 0)
                return (-1);
        x = divrnd(frequency / divisor, speed);
        if (x <= 0)
                return (-1);
        err = divrnd(((quad_t)frequency) * 1000 / divisor, speed * x) - 1000;
        if (err < 0)
                err = -err;
        if (err > COM_TOLERANCE)
                return (-1);
        return (x);

#undef  divrnd
}

#ifdef COM_DEBUG
int     com_debug = 0;

void comstatus(struct com_softc *, const char *);
void
comstatus(struct com_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

int
com_probe_subr(struct com_regs *regs)
{

        /* force access to id reg */
        CSR_WRITE_1(regs, COM_REG_LCR, LCR_8BITS);
        CSR_WRITE_1(regs, COM_REG_IIR, 0);
        if ((CSR_READ_1(regs, COM_REG_LCR) != LCR_8BITS) ||
            (CSR_READ_1(regs, COM_REG_IIR) & 0x38))
                return (0);

        return (1);
}

int
comprobe1(bus_space_tag_t iot, bus_space_handle_t ioh)
{
        struct com_regs regs;

        regs.cr_iot = iot;
        regs.cr_ioh = ioh;
#ifdef  COM_REGMAP
        memcpy(regs.cr_map, com_std_map, sizeof (regs.cr_map));
#endif

        return com_probe_subr(&regs);
}

/*
 * No locking in this routine; it is only called during attach,
 * or with the port already locked.
 */
static void
com_enable_debugport(struct com_softc *sc)
{

        /* Turn on line break interrupt, set carrier. */
        sc->sc_ier = IER_ERXRDY;
        if (sc->sc_type == COM_TYPE_PXA2x0)
                sc->sc_ier |= IER_EUART | IER_ERXTOUT;
        CSR_WRITE_1(&sc->sc_regs, COM_REG_IER, sc->sc_ier);
        SET(sc->sc_mcr, MCR_DTR | MCR_RTS);
        CSR_WRITE_1(&sc->sc_regs, COM_REG_MCR, sc->sc_mcr);
}

void
com_attach_subr(struct com_softc *sc)
{
        struct com_regs *regsp = &sc->sc_regs;
        struct tty *tp;
#ifdef COM_16650
        u_int8_t lcr;
#endif
        const char *fifo_msg = NULL;

        aprint_naive("\n");

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

        /* Disable interrupts before configuring the device. */
        if (sc->sc_type == COM_TYPE_PXA2x0)
                sc->sc_ier = IER_EUART;
        else
                sc->sc_ier = 0;

        CSR_WRITE_1(regsp, COM_REG_IER, sc->sc_ier);

        if (regsp->cr_iot == comcons_info.regs.cr_iot &&
            regsp->cr_iobase == comcons_info.regs.cr_iobase) {
                comconsattached = 1;

                if (cn_tab == NULL && comcnreattach() != 0) {
                        printf("can't re-init serial console @%zx\n",
                            (size_t)comcons_info.regs.cr_iobase);
                }

                /* 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);
        }

        /* Probe for FIFO */
        switch (sc->sc_type) {
        case COM_TYPE_HAYESP:
                goto fifodone;

        case COM_TYPE_AU1x00:
                sc->sc_fifolen = 16;
                fifo_msg = "Au1X00 UART, working fifo";
                SET(sc->sc_hwflags, COM_HW_FIFO);
                goto fifodelay;
 
        case COM_TYPE_16550_NOERS:
                sc->sc_fifolen = 16;
                fifo_msg = "ns16650, no ERS, working fifo";
                SET(sc->sc_hwflags, COM_HW_FIFO);
                goto fifodelay;

        case COM_TYPE_OMAP:
                sc->sc_fifolen = 64;
                fifo_msg = "OMAP UART, working fifo";
                SET(sc->sc_hwflags, COM_HW_FIFO);
                goto fifodelay;
        }

        sc->sc_fifolen = 1;
        /* look for a NS 16550AF UART with FIFOs */
        CSR_WRITE_1(regsp, COM_REG_FIFO,
            FIFO_ENABLE | FIFO_RCV_RST | FIFO_XMT_RST | FIFO_TRIGGER_14);
        delay(100);
        if (ISSET(CSR_READ_1(regsp, COM_REG_IIR), IIR_FIFO_MASK)
            == IIR_FIFO_MASK)
                if (ISSET(CSR_READ_1(regsp, COM_REG_FIFO), FIFO_TRIGGER_14)
                    == FIFO_TRIGGER_14) {
                        SET(sc->sc_hwflags, COM_HW_FIFO);

#ifdef COM_16650
                        /*
                         * IIR changes into the EFR if LCR is set to LCR_EERS
                         * on 16650s. We also know IIR != 0 at this point.
                         * Write 0 into the EFR, and read it. If the result
                         * is 0, we have a 16650.
                         *
                         * Older 16650s were broken; the test to detect them
                         * is taken from the Linux driver. Apparently
                         * setting DLAB enable gives access to the EFR on
                         * these chips.
                         */
                        lcr = CSR_READ_1(regsp, COM_REG_LCR);
                        CSR_WRITE_1(regsp, COM_REG_LCR, LCR_EERS);
                        CSR_WRITE_1(regsp, COM_REG_EFR, 0);
                        if (CSR_READ_1(regsp, COM_REG_EFR) == 0) {
                                CSR_WRITE_1(regsp, COM_REG_LCR,
                                    lcr | LCR_DLAB);
                                if (CSR_READ_1(regsp, COM_REG_EFR) == 0) {
                                        CLR(sc->sc_hwflags, COM_HW_FIFO);
                                        sc->sc_fifolen = 0;
                                } else {
                                        SET(sc->sc_hwflags, COM_HW_FLOW);
                                        sc->sc_fifolen = 32;
                                }
                        } else
#endif
                                sc->sc_fifolen = 16;

#ifdef COM_16650
                        CSR_WRITE_1(regsp, COM_REG_LCR, lcr);
                        if (sc->sc_fifolen == 0)
                                fifo_msg = "st16650, broken fifo";
                        else if (sc->sc_fifolen == 32)
                                fifo_msg = "st16650a, working fifo";
                        else
#endif
                                fifo_msg = "ns16550a, working fifo";
                } else
                        fifo_msg = "ns16550, broken fifo";
        else
                fifo_msg = "ns8250 or ns16450, no fifo";
        CSR_WRITE_1(regsp, COM_REG_FIFO, 0);
fifodelay:
        /*
         * Some chips will clear down both Tx and Rx FIFOs when zero is
         * written to com_fifo. If this chip is the console, writing zero
         * results in some of the chip/FIFO description being lost, so delay
         * printing it until now.
         */
        delay(10);
        aprint_normal(": %s\n", fifo_msg);
        if (ISSET(sc->sc_hwflags, COM_HW_TXFIFO_DISABLE)) {
                sc->sc_fifolen = 1;
                aprint_normal_dev(sc->sc_dev, "txfifo disabled\n");
        }

fifodone:

        tp = ttymalloc();
        tp->t_oproc = comstart;
        tp->t_param = comparam;
        tp->t_hwiflow = comhwiflow;

        sc->sc_tty = tp;
        sc->sc_rbuf = malloc(com_rbuf_size << 1, M_DEVBUF, M_NOWAIT);
        sc->sc_rbput = sc->sc_rbget = sc->sc_rbuf;
        sc->sc_rbavail = com_rbuf_size;
        if (sc->sc_rbuf == NULL) {
                aprint_error_dev(sc->sc_dev,
                    "unable to allocate ring buffer\n");
                return;
        }
        sc->sc_ebuf = sc->sc_rbuf + (com_rbuf_size << 1);

        tty_attach(tp);

        if (!ISSET(sc->sc_hwflags, COM_HW_NOIEN))
                SET(sc->sc_mcr, MCR_IENABLE);

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

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

                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->cr_iot == comkgdbregs.cr_iot &&
            regsp->cr_iobase == comkgdbregs.cr_iobase) {
                if (!ISSET(sc->sc_hwflags, COM_HW_CONSOLE)) {
                        com_kgdb_attached = 1;

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

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

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

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

        com_config(sc);

        SET(sc->sc_hwflags, COM_HW_DEV_OK);
}

void
com_config(struct com_softc *sc)
{
        struct com_regs *regsp = &sc->sc_regs;

        /* Disable interrupts before configuring the device. */
        if (sc->sc_type == COM_TYPE_PXA2x0)
                sc->sc_ier = IER_EUART;
        else
                sc->sc_ier = 0;
        CSR_WRITE_1(regsp, COM_REG_IER, sc->sc_ier);
        (void) CSR_READ_1(regsp, COM_REG_IIR);

#ifdef COM_HAYESP
        /* Look for a Hayes ESP board. */
        if (sc->sc_type == COM_TYPE_HAYESP) {

                /* Set 16550 compatibility mode */
                bus_space_write_1(regsp->cr_iot, sc->sc_hayespioh, HAYESP_CMD1,
                                  HAYESP_SETMODE);
                bus_space_write_1(regsp->cr_iot, sc->sc_hayespioh, HAYESP_CMD2,
                                  HAYESP_MODE_FIFO|HAYESP_MODE_RTS|
                                  HAYESP_MODE_SCALE);

                /* Set RTS/CTS flow control */
                bus_space_write_1(regsp->cr_iot, sc->sc_hayespioh, HAYESP_CMD1,
                                  HAYESP_SETFLOWTYPE);
                bus_space_write_1(regsp->cr_iot, sc->sc_hayespioh, HAYESP_CMD2,
                                  HAYESP_FLOW_RTS);
                bus_space_write_1(regsp->cr_iot, sc->sc_hayespioh, HAYESP_CMD2,
                                  HAYESP_FLOW_CTS);

                /* Set flow control levels */
                bus_space_write_1(regsp->cr_iot, sc->sc_hayespioh, HAYESP_CMD1,
                                  HAYESP_SETRXFLOW);
                bus_space_write_1(regsp->cr_iot, sc->sc_hayespioh, HAYESP_CMD2,
                                  HAYESP_HIBYTE(HAYESP_RXHIWMARK));
                bus_space_write_1(regsp->cr_iot, sc->sc_hayespioh, HAYESP_CMD2,
                                  HAYESP_LOBYTE(HAYESP_RXHIWMARK));
                bus_space_write_1(regsp->cr_iot, sc->sc_hayespioh, HAYESP_CMD2,
                                  HAYESP_HIBYTE(HAYESP_RXLOWMARK));
                bus_space_write_1(regsp->cr_iot, sc->sc_hayespioh, HAYESP_CMD2,
                                  HAYESP_LOBYTE(HAYESP_RXLOWMARK));
        }
#endif

        if (ISSET(sc->sc_hwflags, COM_HW_CONSOLE|COM_HW_KGDB))
                com_enable_debugport(sc);
}

#if 0
static int
comcngetc_detached(dev_t dev)
{
        return 0;
}

static void
comcnputc_detached(dev_t dev, int c)
{
}
#endif

int
com_detach(device_t self, int flags)
{
        struct com_softc *sc = device_private(self);
        int maj, mn;

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

        if (ISSET(sc->sc_hwflags, COM_HW_CONSOLE) &&
            (flags & DETACH_SHUTDOWN) != 0)
                return EBUSY;

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

        if (ISSET(sc->sc_hwflags, COM_HW_CONSOLE)) {
                comconsattached = 0;
                cn_tab = NULL;
        }

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

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

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

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

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

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

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

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

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

        return (0);
}

void
com_shutdown(struct com_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, RX_IBUF_BLOCKED);
        com_hwiflow(sc);

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

        /*
         * Hang up if necessary.  Wait a bit, so the other side has time to
         * notice even if we immediately open the port again.
         * Avoid tsleeping above splhigh().
         */
        if (ISSET(tp->t_cflag, HUPCL)) {
                com_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. */
        if (ISSET(sc->sc_hwflags, COM_HW_CONSOLE)) {
                sc->sc_ier = IER_ERXRDY; /* interrupt on break */
                if (sc->sc_type == COM_TYPE_PXA2x0)
                        sc->sc_ier |= IER_ERXTOUT;
        } else
                sc->sc_ier = 0;

        if (sc->sc_type == COM_TYPE_PXA2x0)
                sc->sc_ier |= IER_EUART;

        CSR_WRITE_1(&sc->sc_regs, COM_REG_IER, sc->sc_ier);

        mutex_spin_exit(&sc->sc_lock);

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

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

        sc = device_lookup_private(&com_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;


                if (sc->enable) {
                        if ((*sc->enable)(sc)) {
                                splx(s);
                                aprint_error_dev(sc->sc_dev,
                                    "device enable failed\n");
                                return (EIO);
                        }
                        mutex_spin_enter(&sc->sc_lock);
                        sc->enabled = 1;
                        com_config(sc);
                } else {
                        mutex_spin_enter(&sc->sc_lock);
                }

                /* Turn on interrupts. */
                sc->sc_ier = IER_ERXRDY | IER_ERLS | IER_EMSC;
                if (sc->sc_type == COM_TYPE_PXA2x0)
                        sc->sc_ier |= IER_EUART | IER_ERXTOUT;
                CSR_WRITE_1(&sc->sc_regs, COM_REG_IER, sc->sc_ier);

                /* Fetch the current modem control status, needed later. */
                sc->sc_msr = CSR_READ_1(&sc->sc_regs, COM_REG_MSR);

                /* 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);

                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, COM_HW_CONSOLE)) {
                        t.c_ospeed = comcons_info.rate;
                        t.c_cflag = comcons_info.cflag;
                } 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 comparam() will do something. */
                tp->t_ospeed = 0;
                (void) comparam(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.
                 */
                com_modem(sc, 1);

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

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

                mutex_spin_exit(&sc->sc_lock);
        }

        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.
                 */
                com_shutdown(sc);
        }

        return (error);
}

int
comclose(dev_t dev, int flag, int mode, struct lwp *l)
{
        struct com_softc *sc =
            device_lookup_private(&com_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.
                 */
                com_shutdown(sc);
        }

        return (0);
}

int
comread(dev_t dev, struct uio *uio, int flag)
{
        struct com_softc *sc =
            device_lookup_private(&com_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
comwrite(dev_t dev, struct uio *uio, int flag)
{
        struct com_softc *sc =
            device_lookup_private(&com_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
compoll(dev_t dev, int events, struct lwp *l)
{
        struct com_softc *sc =
            device_lookup_private(&com_cd, COMUNIT(dev));
        struct tty *tp = sc->sc_tty;

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

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

struct tty *
comtty(dev_t dev)
{
        struct com_softc *sc =
            device_lookup_private(&com_cd, COMUNIT(dev));
        struct tty *tp = sc->sc_tty;

        return (tp);
}

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

        sc = device_lookup_private(&com_cd, COMUNIT(dev));
        if (sc == NULL)
                return ENXIO;
        if (COM_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:
                com_break(sc, 1);
                break;

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

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

        case TIOCCDTR:
                com_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_com(sc, cmd, *(int *)data);
                break;

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

        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;

        default:
                error = EPASSTHROUGH;
                break;
        }

        mutex_spin_exit(&sc->sc_lock);

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

        return (error);
}

integrate void
com_schedrx(struct com_softc *sc)
{

        sc->sc_rx_ready = 1;

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

void
com_break(struct com_softc *sc, int onoff)
{

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

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

void
com_modem(struct com_softc *sc, int onoff)
{

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

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

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

void
tiocm_to_com(struct com_softc *sc, u_long how, int ttybits)
{
        u_char combits;

        combits = 0;
        if (ISSET(ttybits, TIOCM_DTR))
                SET(combits, MCR_DTR);
        if (ISSET(ttybits, TIOCM_RTS))
                SET(combits, MCR_RTS);

        switch (how) {
        case TIOCMBIC:
                CLR(sc->sc_mcr, combits);
                break;

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

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

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

int
com_to_tiocm(struct com_softc *sc)
{
        u_char combits;
        int ttybits = 0;

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

        combits = sc->sc_msr;
        if (ISSET(combits, MSR_DCD))
                SET(ttybits, TIOCM_CD);
        if (ISSET(combits, MSR_CTS))
                SET(ttybits, TIOCM_CTS);
        if (ISSET(combits, MSR_DSR))
                SET(ttybits, TIOCM_DSR);
        if (ISSET(combits, MSR_RI | MSR_TERI))
                SET(ttybits, TIOCM_RI);

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

        return (ttybits);
}

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

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

        return (lcr);
}

int
comparam(struct tty *tp, struct termios *t)
{
        struct com_softc *sc =
            device_lookup_private(&com_cd, COMUNIT(tp->t_dev));
        int ospeed;
        u_char lcr;

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

#ifdef COM_HAYESP
        if (sc->sc_type == COM_TYPE_HAYESP) {
                int prescaler, speed;

                /*
                 * Calculate UART clock prescaler.  It should be in
                 * range of 0 .. 3.
                 */
                for (prescaler = 0, speed = t->c_ospeed; prescaler < 4;
                    prescaler++, speed /= 2)
                        if ((ospeed = comspeed(speed, sc->sc_frequency,
                                               sc->sc_type)) > 0)
                                break;

                if (prescaler == 4)
                        return (EINVAL);
                sc->sc_prescaler = prescaler;
        } else
#endif
        ospeed = comspeed(t->c_ospeed, sc->sc_frequency, sc->sc_type);

        /* Check requested parameters. */
        if (ospeed < 0)
                return (EINVAL);
        if (t->c_ispeed && t->c_ispeed != t->c_ospeed)
                return (EINVAL);

        /*
         * For the console, always force CLOCAL and !HUPCL, so that the port
         * is always active.
         */
        if (ISSET(sc->sc_swflags, TIOCFLAG_SOFTCAR) ||
            ISSET(sc->sc_hwflags, 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);

        lcr = ISSET(sc->sc_lcr, LCR_SBREAK) | cflag2lcr(t->c_cflag);

        mutex_spin_enter(&sc->sc_lock);

        sc->sc_lcr = lcr;

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

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

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

        /*
         * 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 (sc->sc_type == COM_TYPE_HAYESP)
                sc->sc_fifo = FIFO_DMA_MODE | FIFO_ENABLE | FIFO_TRIGGER_8;
        else if (ISSET(sc->sc_hwflags, COM_HW_FIFO)) {
                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;
        } else
                sc->sc_fifo = 0;

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

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

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

        mutex_spin_exit(&sc->sc_lock);

        /*
         * Update the tty layer's idea of the carrier bit, in case we changed
         * CLOCAL or MDMBUF.  We don't hang up here; we only do that by
         * explicit request.
         */
        (void) (*tp->t_linesw->l_modem)(tp, ISSET(sc->sc_msr, MSR_DCD));

#ifdef 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;
                        comstart(tp);
                }
        }

        return (0);
}

void
com_iflush(struct com_softc *sc)
{
        struct com_regs *regsp = &sc->sc_regs;
#ifdef DIAGNOSTIC
        int reg;
#endif
        int timo;

#ifdef DIAGNOSTIC
        reg = 0xffff;
#endif
        timo = 50000;
        /* flush any pending I/O */
        while (ISSET(CSR_READ_1(regsp, COM_REG_LSR), LSR_RXRDY)
            && --timo)
#ifdef DIAGNOSTIC
                reg =
#else
                    (void)
#endif
                    CSR_READ_1(regsp, COM_REG_RXDATA);
#ifdef DIAGNOSTIC
        if (!timo)
                aprint_error_dev(sc->sc_dev, "com_iflush timeout %02x\n", reg);
#endif
}

void
com_loadchannelregs(struct com_softc *sc)
{
        struct com_regs *regsp = &sc->sc_regs;

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

        if (sc->sc_type == COM_TYPE_PXA2x0)
                CSR_WRITE_1(regsp, COM_REG_IER, IER_EUART);
        else
                CSR_WRITE_1(regsp, COM_REG_IER, 0);

        if (sc->sc_type == COM_TYPE_OMAP) {
                /* disable before changing settings */
                CSR_WRITE_1(regsp, COM_REG_MDR1, MDR1_MODE_DISABLE);
        }

        if (ISSET(sc->sc_hwflags, COM_HW_FLOW)) {
                KASSERT(sc->sc_type != COM_TYPE_AU1x00);
                KASSERT(sc->sc_type != COM_TYPE_16550_NOERS);
                /* no EFR on alchemy */
                CSR_WRITE_1(regsp, COM_REG_EFR, sc->sc_efr);
                CSR_WRITE_1(regsp, COM_REG_LCR, LCR_EERS);
        }
        if (sc->sc_type == COM_TYPE_AU1x00) {
                /* alchemy has single separate 16-bit clock divisor register */
                CSR_WRITE_2(regsp, COM_REG_DLBL, sc->sc_dlbl +
                    (sc->sc_dlbh << 8));
        } else {
                CSR_WRITE_1(regsp, COM_REG_LCR, sc->sc_lcr | LCR_DLAB);
                CSR_WRITE_1(regsp, COM_REG_DLBL, sc->sc_dlbl);
                CSR_WRITE_1(regsp, COM_REG_DLBH, sc->sc_dlbh);
        }
        CSR_WRITE_1(regsp, COM_REG_LCR, sc->sc_lcr);
        CSR_WRITE_1(regsp, COM_REG_MCR, sc->sc_mcr_active = sc->sc_mcr);
        CSR_WRITE_1(regsp, COM_REG_FIFO, sc->sc_fifo);
#ifdef COM_HAYESP
        if (sc->sc_type == COM_TYPE_HAYESP) {
                bus_space_write_1(regsp->cr_iot, sc->sc_hayespioh, HAYESP_CMD1,
                    HAYESP_SETPRESCALER);
                bus_space_write_1(regsp->cr_iot, sc->sc_hayespioh, HAYESP_CMD2,
                    sc->sc_prescaler);
        }
#endif
        if (sc->sc_type == COM_TYPE_OMAP) {
                /* setup the fifos.  the FCR value is not used as long
                   as SCR[6] and SCR[7] are 0, which they are at reset
                   and we never touch the SCR register */
                uint8_t rx_fifo_trig = 40;
                uint8_t tx_fifo_trig = 60;
                uint8_t rx_start = 8;
                uint8_t rx_halt = 60;
                uint8_t tlr_value = ((rx_fifo_trig>>2) << 4) | (tx_fifo_trig>>2);
                uint8_t tcr_value = ((rx_start>>2) << 4) | (rx_halt>>2);

                /* enable access to TCR & TLR */
                CSR_WRITE_1(regsp, COM_REG_MCR, sc->sc_mcr | MCR_TCR_TLR);

                /* write tcr and tlr values */
                CSR_WRITE_1(regsp, COM_REG_TLR, tlr_value);
                CSR_WRITE_1(regsp, COM_REG_TCR, tcr_value);

                /* disable access to TCR & TLR */
                CSR_WRITE_1(regsp, COM_REG_MCR, sc->sc_mcr);

                /* enable again, but mode is based on speed */
                if (sc->sc_tty->t_termios.c_ospeed > 230400) {
                        CSR_WRITE_1(regsp, COM_REG_MDR1, MDR1_MODE_UART_13X);
                } else {
                        CSR_WRITE_1(regsp, COM_REG_MDR1, MDR1_MODE_UART_16X);
                }
        }

        CSR_WRITE_1(regsp, COM_REG_IER, sc->sc_ier);
}

int
comhwiflow(struct tty *tp, int block)
{
        struct com_softc *sc =
            device_lookup_private(&com_cd, COMUNIT(tp->t_dev));

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

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

        mutex_spin_enter(&sc->sc_lock);

        if (block) {
                if (!ISSET(sc->sc_rx_flags, RX_TTY_BLOCKED)) {
                        SET(sc->sc_rx_flags, RX_TTY_BLOCKED);
                        com_hwiflow(sc);
                }
        } else {
                if (ISSET(sc->sc_rx_flags, RX_TTY_OVERFLOWED)) {
                        CLR(sc->sc_rx_flags, RX_TTY_OVERFLOWED);
                        com_schedrx(sc);
                }
                if (ISSET(sc->sc_rx_flags, RX_TTY_BLOCKED)) {
                        CLR(sc->sc_rx_flags, RX_TTY_BLOCKED);
                        com_hwiflow(sc);
                }
        }

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

/*
 * (un)block input via hw flowcontrol
 */
void
com_hwiflow(struct com_softc *sc)
{
        struct com_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);
        }
        CSR_WRITE_1(regsp, COM_REG_MCR, sc->sc_mcr_active);
}


void
comstart(struct tty *tp)
{
        struct com_softc *sc =
            device_lookup_private(&com_cd, COMUNIT(tp->t_dev));
        struct com_regs *regsp = &sc->sc_regs;
        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);

                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;

        /* Enable transmit completion interrupts if necessary. */
        if (!ISSET(sc->sc_ier, IER_ETXRDY)) {
                SET(sc->sc_ier, IER_ETXRDY);
                CSR_WRITE_1(regsp, COM_REG_IER, sc->sc_ier);
        }

        /* Output the first chunk of the contiguous buffer. */
        if (!ISSET(sc->sc_hwflags, COM_HW_NO_TXPRELOAD)) {
                u_int n;

                n = sc->sc_tbc;
                if (n > sc->sc_fifolen)
                        n = sc->sc_fifolen;
                CSR_WRITE_MULTI(regsp, COM_REG_TXDATA, sc->sc_tba, n);
                sc->sc_tbc -= n;
                sc->sc_tba += n;
        }

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

/*
 * Stop output on a line.
 */
void
comstop(struct tty *tp, int flag)
{
        struct com_softc *sc =
            device_lookup_private(&com_cd, COMUNIT(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
comdiag(void *arg)
{
        struct com_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");
}

integrate void
com_rxsoft(struct com_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 lsr;
        int code;

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

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

        /* If not yet open, drop the entire buffer content here */
        if (!ISSET(tp->t_state, TS_ISOPEN)) {
                get += cc << 1;
                if (get >= end)
                        get -= com_rbuf_size << 1;
                cc = 0;
        }
        while (cc) {
                code = get[0];
                lsr = get[1];
                if (ISSET(lsr, LSR_OE | LSR_BI | LSR_FE | LSR_PE)) {
                        if (ISSET(lsr, LSR_OE)) {
                                sc->sc_overflows++;
                                if (sc->sc_errors++ == 0)
                                        callout_reset(&sc->sc_diag_callout,
                                            60 * hz, comdiag, sc);
                        }
                        if (ISSET(lsr, LSR_BI | LSR_FE))
                                SET(code, TTY_FE);
                        if (ISSET(lsr, LSR_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 -= com_rbuf_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;
                mutex_spin_enter(&sc->sc_lock);

                cc = sc->sc_rbavail += scc - cc;
                /* Buffers should be ok again, release possible block. */
                if (cc >= sc->sc_r_lowat) {
                        if (ISSET(sc->sc_rx_flags, RX_IBUF_OVERFLOWED)) {
                                CLR(sc->sc_rx_flags, RX_IBUF_OVERFLOWED);
                                SET(sc->sc_ier, IER_ERXRDY);
#ifdef COM_PXA2X0
                                if (sc->sc_type == COM_TYPE_PXA2x0)
                                        SET(sc->sc_ier, IER_ERXTOUT);
#endif
                                CSR_WRITE_1(&sc->sc_regs, COM_REG_IER, sc->sc_ier);
                        }
                        if (ISSET(sc->sc_rx_flags, RX_IBUF_BLOCKED)) {
                                CLR(sc->sc_rx_flags, RX_IBUF_BLOCKED);
                                com_hwiflow(sc);
                        }
                }
                mutex_spin_exit(&sc->sc_lock);
        }
}

integrate void
com_txsoft(struct com_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
com_stsoft(struct com_softc *sc, struct tty *tp)
{
        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;
                }
        }

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

void
comsoft(void *arg)
{
        struct com_softc *sc = arg;
        struct tty *tp;

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

        tp = sc->sc_tty;

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

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

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

int
comintr(void *arg)
{
        struct com_softc *sc = arg;
        struct com_regs *regsp = &sc->sc_regs;

        u_char *put, *end;
        u_int cc;
        u_char lsr, iir;

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

        KASSERT(regsp != NULL);

        mutex_spin_enter(&sc->sc_lock);
        iir = CSR_READ_1(regsp, COM_REG_IIR);
        if (ISSET(iir, IIR_NOPEND)) {
                mutex_spin_exit(&sc->sc_lock);
                return (0);
        }

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

again:  do {
                u_char  msr, delta;

                lsr = CSR_READ_1(regsp, COM_REG_LSR);
                if (ISSET(lsr, LSR_BI)) {
                        int cn_trapped = 0;

                        cn_check_magic(sc->sc_tty->t_dev,
                                       CNC_BREAK, com_cnm_state);
                        if (cn_trapped)
                                continue;
#if defined(KGDB) && !defined(DDB)
                        if (ISSET(sc->sc_hwflags, COM_HW_KGDB)) {
                                kgdb_connect(1);
                                continue;
                        }
#endif
                }

                if (ISSET(lsr, LSR_RCV_MASK) &&
                    !ISSET(sc->sc_rx_flags, RX_IBUF_OVERFLOWED)) {
                        while (cc > 0) {
                                int cn_trapped = 0;
                                put[0] = CSR_READ_1(regsp, COM_REG_RXDATA);
                                put[1] = lsr;
                                cn_check_magic(sc->sc_tty->t_dev,
                                               put[0], com_cnm_state);
                                if (cn_trapped)
                                        goto next;
                                put += 2;
                                if (put >= end)
                                        put = sc->sc_rbuf;
                                cc--;
                        next:
                                lsr = CSR_READ_1(regsp, COM_REG_LSR);
                                if (!ISSET(lsr, LSR_RCV_MASK))
                                        break;
                        }

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

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

                        /*
                         * If we're out of space, disable receive interrupts
                         * until the queue has drained a bit.
                         */
                        if (!cc) {
                                SET(sc->sc_rx_flags, RX_IBUF_OVERFLOWED);
#ifdef COM_PXA2X0
                                if (sc->sc_type == COM_TYPE_PXA2x0)
                                        CLR(sc->sc_ier, IER_ERXRDY|IER_ERXTOUT);
                                else
#endif
                                        CLR(sc->sc_ier, IER_ERXRDY);
                                CSR_WRITE_1(regsp, COM_REG_IER, sc->sc_ier);
                        }
                } else {
                        if ((iir & (IIR_RXRDY|IIR_TXRDY)) == IIR_RXRDY) {
                                (void) CSR_READ_1(regsp, COM_REG_RXDATA);
                                continue;
                        }
                }

                msr = CSR_READ_1(regsp, COM_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);
                }

                /*
                 * 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 COM_DEBUG
                                if (com_debug)
                                        comstatus(sc, "comintr  ");
#endif
                        }

                        sc->sc_st_check = 1;
                }
        } while (!ISSET((iir =
            CSR_READ_1(regsp, COM_REG_IIR)), IIR_NOPEND) &&
            /*
             * Since some device (e.g., ST16C1550) doesn't clear IIR_TXRDY
             * by IIR read, so we can't do this way: `process all interrupts,
             * then do TX if possble'.
             */
            (iir & IIR_IMASK) != IIR_TXRDY);

        /*
         * Read LSR again, since there may be an interrupt between
         * the last LSR read and IIR read above.
         */
        lsr = CSR_READ_1(regsp, COM_REG_LSR);

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

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

                        n = sc->sc_tbc;
                        if (n > sc->sc_fifolen)
                                n = sc->sc_fifolen;
                        CSR_WRITE_MULTI(regsp, COM_REG_TXDATA, sc->sc_tba, n);
                        sc->sc_tbc -= n;
                        sc->sc_tba += n;
                } else {
                        /* Disable transmit completion interrupts if necessary. */
                        if (ISSET(sc->sc_ier, IER_ETXRDY)) {
                                CLR(sc->sc_ier, IER_ETXRDY);
                                CSR_WRITE_1(regsp, COM_REG_IER, sc->sc_ier);
                        }
                        if (sc->sc_tx_busy) {
                                sc->sc_tx_busy = 0;
                                sc->sc_tx_done = 1;
                        }
                }
        }

        if (!ISSET((iir = CSR_READ_1(regsp, COM_REG_IIR)), IIR_NOPEND))
                goto again;

        mutex_spin_exit(&sc->sc_lock);

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

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

        return (1);
}

/*
 * The following functions are polled getc and putc routines, shared
 * by the console and kgdb glue.
 *
 * The read-ahead code is so that you can detect pending in-band
 * cn_magic in polled mode while doing output rather than having to
 * wait until the kernel decides it needs input.
 */

#define MAX_READAHEAD   20
static int com_readahead[MAX_READAHEAD];
static int com_readaheadcount = 0;

int
com_common_getc(dev_t dev, struct com_regs *regsp)
{
        int s = splserial();
        u_char stat, c;

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

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

        /* block until a character becomes available */
        while (!ISSET(stat = CSR_READ_1(regsp, COM_REG_LSR), LSR_RXRDY))
                ;

        c = CSR_READ_1(regsp, COM_REG_RXDATA);
        stat = CSR_READ_1(regsp, COM_REG_IIR);
        {
                int cn_trapped = 0; /* unused */
#ifdef DDB
                extern int db_active;
                if (!db_active)
#endif
                        cn_check_magic(dev, c, com_cnm_state);
        }
        splx(s);
        return (c);
}

static void
com_common_putc(dev_t dev, struct com_regs *regsp, int c)
{
        int s = splserial();
        int cin, stat, timo;

        if (com_readaheadcount < MAX_READAHEAD
             && ISSET(stat = CSR_READ_1(regsp, COM_REG_LSR), LSR_RXRDY)) {
                int cn_trapped = 0;
                cin = CSR_READ_1(regsp, COM_REG_RXDATA);
                stat = CSR_READ_1(regsp, COM_REG_IIR);
                cn_check_magic(dev, cin, com_cnm_state);
                com_readahead[com_readaheadcount++] = cin;
        }

        /* wait for any pending transmission to finish */
        timo = 150000;
        while (!ISSET(CSR_READ_1(regsp, COM_REG_LSR), LSR_TXRDY) && --timo)
                continue;

        CSR_WRITE_1(regsp, COM_REG_TXDATA, c);
        COM_BARRIER(regsp, BR | BW);

        splx(s);
}

/*
 * Initialize UART for use as console or KGDB line.
 */
int
cominit(struct com_regs *regsp, int rate, int frequency, int type,
    tcflag_t cflag)
{

        if (bus_space_map(regsp->cr_iot, regsp->cr_iobase, regsp->cr_nports, 0,
                &regsp->cr_ioh))
                return (ENOMEM); /* ??? */

        if (type == COM_TYPE_OMAP) {
                /* disable before changing settings */
                CSR_WRITE_1(regsp, COM_REG_MDR1, MDR1_MODE_DISABLE);
        }

        rate = comspeed(rate, frequency, type);
        if (type != COM_TYPE_AU1x00) {
                /* no EFR on alchemy */ 
                if (type != COM_TYPE_16550_NOERS) {
                        CSR_WRITE_1(regsp, COM_REG_LCR, LCR_EERS);
                        CSR_WRITE_1(regsp, COM_REG_EFR, 0);
                }
                CSR_WRITE_1(regsp, COM_REG_LCR, LCR_DLAB);
                CSR_WRITE_1(regsp, COM_REG_DLBL, rate & 0xff);
                CSR_WRITE_1(regsp, COM_REG_DLBH, rate >> 8);
        } else {
                CSR_WRITE_1(regsp, COM_REG_DLBL, rate);
        }
        CSR_WRITE_1(regsp, COM_REG_LCR, cflag2lcr(cflag));
        CSR_WRITE_1(regsp, COM_REG_MCR, MCR_DTR | MCR_RTS);
        CSR_WRITE_1(regsp, COM_REG_FIFO,
            FIFO_ENABLE | FIFO_RCV_RST | FIFO_XMT_RST | FIFO_TRIGGER_1);

        if (type == COM_TYPE_OMAP) {
                /* setup the fifos.  the FCR value is not used as long
                   as SCR[6] and SCR[7] are 0, which they are at reset
                   and we never touch the SCR register */
                uint8_t rx_fifo_trig = 40;
                uint8_t tx_fifo_trig = 60;
                uint8_t rx_start = 8;
                uint8_t rx_halt = 60;
                uint8_t tlr_value = ((rx_fifo_trig>>2) << 4) | (tx_fifo_trig>>2);
                uint8_t tcr_value = ((rx_start>>2) << 4) | (rx_halt>>2);

                /* enable access to TCR & TLR */
                CSR_WRITE_1(regsp, COM_REG_MCR, MCR_DTR | MCR_RTS | MCR_TCR_TLR);

                /* write tcr and tlr values */
                CSR_WRITE_1(regsp, COM_REG_TLR, tlr_value);
                CSR_WRITE_1(regsp, COM_REG_TCR, tcr_value);

                /* disable access to TCR & TLR */
                CSR_WRITE_1(regsp, COM_REG_MCR, MCR_DTR | MCR_RTS);

                /* enable again, but mode is based on speed */
                if (rate > 230400) {
                        CSR_WRITE_1(regsp, COM_REG_MDR1, MDR1_MODE_UART_13X);
                } else {
                        CSR_WRITE_1(regsp, COM_REG_MDR1, MDR1_MODE_UART_16X);
                }
        }

#ifdef COM_PXA2X0
        if (type == COM_TYPE_PXA2x0)
                CSR_WRITE_1(regsp, COM_REG_IER, IER_EUART);
        else
#endif
                CSR_WRITE_1(regsp, COM_REG_IER, 0);

        return (0);
}

int
comcnattach1(struct com_regs *regsp, int rate, int frequency, int type,
    tcflag_t cflag)
{
        int res;

        comcons_info.regs = *regsp;

        res = cominit(&comcons_info.regs, rate, frequency, type, cflag);
        if (res)
                return (res);

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

        comcons_info.frequency = frequency;
        comcons_info.type = type;
        comcons_info.rate = rate;
        comcons_info.cflag = cflag;

        return (0);
}

int
comcnattach(bus_space_tag_t iot, bus_addr_t iobase, int rate, int frequency,
    int type, tcflag_t cflag)
{
        struct com_regs regs;

        memset(&regs, 0, sizeof regs);
        regs.cr_iot = iot;
        regs.cr_iobase = iobase;
        regs.cr_nports = COM_NPORTS;
#ifdef  COM_REGMAP
        memcpy(regs.cr_map, com_std_map, sizeof (regs.cr_map));
#endif

        return comcnattach1(&regs, rate, frequency, type, cflag);
}

static int
comcnreattach(void)
{
        return comcnattach1(&comcons_info.regs, comcons_info.rate,
            comcons_info.frequency, comcons_info.type, comcons_info.cflag);
}

int
comcngetc(dev_t dev)
{

        return (com_common_getc(dev, &comcons_info.regs));
}

/*
 * Console kernel output character routine.
 */
void
comcnputc(dev_t dev, int c)
{

        com_common_putc(dev, &comcons_info.regs, c);
}

void
comcnpollc(dev_t dev, int on)
{

}

#ifdef KGDB
int
com_kgdb_attach1(struct com_regs *regsp, int rate, int frequency, int type,
    tcflag_t cflag)
{
        int res;

        if (regsp->cr_iot == comcons_info.regs.cr_iot &&
            regsp->cr_iobase == comcons_info.regs.cr_iobase) {
#if !defined(DDB)
                return (EBUSY); /* cannot share with console */
#else
                comkgdbregs = *regsp;
                comkgdbregs.cr_ioh = comcons_info.regs.cr_ioh;
#endif
        } else {
                comkgdbregs = *regsp;
                res = cominit(&comkgdbregs, rate, frequency, type, cflag);
                if (res)
                        return (res);

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

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

        return (0);
}

int
com_kgdb_attach(bus_space_tag_t iot, bus_addr_t iobase, int rate,
    int frequency, int type, tcflag_t cflag)
{
        struct com_regs regs;

        regs.cr_iot = iot;
        regs.cr_nports = COM_NPORTS;
        regs.cr_iobase = iobase;
#ifdef COM_REGMAP
        memcpy(regs.cr_map, com_std_map, sizeof (regs.cr_map));
#endif

        return com_kgdb_attach1(&regs, rate, frequency, type, cflag);
}

/* ARGSUSED */
int
com_kgdb_getc(void *arg)
{

        return (com_common_getc(NODEV, &comkgdbregs));
}

/* ARGSUSED */
void
com_kgdb_putc(void *arg, int c)
{

        com_common_putc(NODEV, &comkgdbregs, c);
}
#endif /* KGDB */

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

        if (!comconsattached &&
            iot == comcons_info.regs.cr_iot &&
            iobase == comcons_info.regs.cr_iobase)
                help = comcons_info.regs.cr_ioh;
#ifdef KGDB
        else if (!com_kgdb_attached &&
            iot == comkgdbregs.cr_iot && iobase == comkgdbregs.cr_iobase)
                help = comkgdbregs.cr_ioh;
#endif
        else
                return (0);

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

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

        if (ISSET(sc->sc_hwflags, COM_HW_FIFO))
                CSR_WRITE_1(&sc->sc_regs, COM_REG_FIFO, 0);

        return true;
}

bool
com_suspend(device_t self, pmf_qual_t qual)
{
        struct com_softc *sc = device_private(self);

#if 0
        if (ISSET(sc->sc_hwflags, COM_HW_CONSOLE) && cn_tab == &comcons)
                cn_tab = &comcons_suspend;
#endif

        CSR_WRITE_1(&sc->sc_regs, COM_REG_IER, 0);
        (void)CSR_READ_1(&sc->sc_regs, COM_REG_IIR);

        return true;
}

bool
com_resume(device_t self, pmf_qual_t qual)
{
        struct com_softc *sc = device_private(self);

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

        return true;
}