hp300/dev/dcm.c

/*
 * Copyright (c) 1988 University of Utah.
 * Copyright (c) 1982, 1986, 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * the Systems Programming Group of the University of Utah Computer
 * Science Department.
 *
 * %sccs.include.redist.c%
 *
 * from: $Hdr: dcm.c 1.17 89/10/01$
 *
 *	@(#)dcm.c	7.3 (Berkeley) 06/06/90
 */

/*
 * TODO:
 *	Timeouts
 *	Test console/kgdb support.
 */

#include "dcm.h"
#if NDCM > 0
/*
 *  98642/MUX
 */
#include "param.h"
#include "systm.h"
#include "ioctl.h"
#include "tty.h"
#include "user.h"
#include "conf.h"
#include "file.h"
#include "uio.h"
#include "kernel.h"
#include "syslog.h"
#include "time.h"

#include "device.h"
#include "dcmreg.h"
#include "machine/cpu.h"
#include "machine/isr.h"

#ifndef DEFAULT_BAUD_RATE
#define DEFAULT_BAUD_RATE 9600
#endif

int	ttrstrt();
int	dcmprobe(), dcmstart(), dcmintr(), dcmparam();

struct	driver dcmdriver = {
	dcmprobe, "dcm",
};

#define NDCMLINE (NDCM*4)

struct	tty dcm_tty[NDCMLINE];
int	ndcm = NDCMLINE;

int	dcm_active;
int	dcmsoftCAR[NDCM];
struct	dcmdevice *dcm_addr[NDCM];
struct	isr dcmisr[NDCM];

struct speedtab dcmspeedtab[] = {
	0,	BR_0,
	50,	BR_50,
	75,	BR_75,
	110,	BR_110,
	134,	BR_134,
	150,	BR_150,
	300,	BR_300,
	600,	BR_600,
	1200,	BR_1200,
	1800,	BR_1800,
	2400,	BR_2400,
	4800,	BR_4800,
	9600,	BR_9600,
	19200,	BR_19200,
	38400,	BR_38400,
	-1,	-1
};

/* u-sec per character based on baudrate (assumes 1 start/8 data/1 stop bit) */
#define	DCM_USPERCH(s)	(10000000 / (s))

/*
 * Per board interrupt scheme.  16.7ms is the polling interrupt rate
 * (16.7ms is about 550 buad, 38.4k is 72 chars in 16.7ms).
 */
#define DIS_TIMER	0
#define DIS_PERCHAR	1
#define DIS_RESET	2

int	dcmistype = -1;		/* -1 == dynamic, 0 == timer, 1 == perchar */
int     dcminterval = 5;	/* interval (secs) between checks */
struct	dcmischeme {
	int	dis_perchar;	/* non-zero if interrupting per char */
	long	dis_time;	/* last time examined */
	int	dis_intr;	/* recv interrupts during last interval */
	int	dis_char;	/* characters read during last interval */
} dcmischeme[NDCM];

/*
 * Console support
 */
int	dcmconsole = -1;
int	dcmdefaultrate = DEFAULT_BAUD_RATE;
int	dcmconbrdbusy = 0;
extern	struct tty *constty;

#ifdef KGDB
/*
 * Kernel GDB support
 */
extern int kgdb_dev;
extern int kgdb_rate;
extern int kgdb_debug_init;
#endif

/* #define IOSTATS */

#ifdef DEBUG
int	dcmdebug = 0x00;
#define DDB_SIOERR	0x01
#define DDB_PARAM	0x02
#define DDB_INPUT	0x04
#define DDB_OUTPUT	0x08
#define DDB_INTR	0x10
#define DDB_IOCTL	0x20
#define DDB_INTSCHM	0x40
#define DDB_MODEM	0x80
#define DDB_OPENCLOSE	0x100
#endif

#ifdef IOSTATS
#define	DCMRBSIZE	94
#define DCMXBSIZE	24

struct	dcmstats {
	long	xints;		    /* # of xmit ints */
	long	xchars;		    /* # of xmit chars */
	long	xempty;		    /* times outq is empty in dcmstart */
	long	xrestarts;	    /* times completed while xmitting */
	long	rints;		    /* # of recv ints */
	long	rchars;		    /* # of recv chars */
	long	xsilo[DCMXBSIZE+2]; /* times this many chars xmit on one int */
	long	rsilo[DCMRBSIZE+2]; /* times this many chars read on one int */
} dcmstats[NDCM];
#endif

#define UNIT(x)		minor(x)
#define	BOARD(x)	(((x) >> 2) & 0x3f)
#define PORT(x)		((x) & 3)
#define MKUNIT(b,p)	(((b) << 2) | (p))

dcmprobe(hd)
	register struct hp_device *hd;
{
	register struct dcmdevice *dcm;
	register int i;
	register int timo = 0;
	int s, brd, isconsole;

	dcm = (struct dcmdevice *)hd->hp_addr;
	if ((dcm->dcm_rsid & 0x1f) != DCMID)
		return (0);
	brd = hd->hp_unit;
	isconsole = (brd == BOARD(dcmconsole));
	/*
	 * XXX selected console device (CONSUNIT) as determined by
	 * dcmcnprobe does not agree with logical numbering imposed
	 * by the config file (i.e. lowest address DCM is not unit
	 * CONSUNIT).  Don't recognize this card.
	 */
	if (isconsole && dcm != dcm_addr[BOARD(dcmconsole)])
		return(0);

	/*
	 * Empirically derived self-test magic
	 */
	s = spltty();
	dcm->dcm_rsid = DCMRS;
	DELAY(50000);	/* 5000 is not long enough */
	dcm->dcm_rsid = 0;
	dcm->dcm_ic = IC_IE;
	dcm->dcm_cr = CR_SELFT;
	while ((dcm->dcm_ic & IC_IR) == 0)
		if (++timo == 20000)
			return(0);
	DELAY(50000)	/* XXX why is this needed ???? */
	while ((dcm->dcm_iir & IIR_SELFT) == 0)
		if (++timo == 400000)
			return(0);
	DELAY(50000)	/* XXX why is this needed ???? */
	if (dcm->dcm_stcon != ST_OK) {
		if (!isconsole)
			printf("dcm%d: self test failed: %x\n",
			       brd, dcm->dcm_stcon);
		return(0);
	}
	dcm->dcm_ic = IC_ID;
	splx(s);

	hd->hp_ipl = DCMIPL(dcm->dcm_ic);
	dcm_addr[brd] = dcm;
	dcm_active |= 1 << brd;
	dcmsoftCAR[brd] = hd->hp_flags;
	dcmisr[brd].isr_ipl = hd->hp_ipl;
	dcmisr[brd].isr_arg = brd;
	dcmisr[brd].isr_intr = dcmintr;
	isrlink(&dcmisr[brd]);
#ifdef KGDB
	if (major(kgdb_dev) == 2 && BOARD(kgdb_dev) == brd) {
		if (dcmconsole == UNIT(kgdb_dev))
			kgdb_dev = -1;	/* can't debug over console port */
		else {
			(void) dcminit(kgdb_dev, kgdb_rate);
			if (kgdb_debug_init) {
				printf("dcm%d: kgdb waiting...",
				       UNIT(kgdb_dev));
				/* trap into kgdb */
				asm("trap #15;");
				printf("connected.\n");
			} else
				printf("dcm%d: kgdb enabled\n",
				       UNIT(kgdb_dev));
		}
	}
#endif
	if (dcmistype == DIS_TIMER)
		dcmsetischeme(brd, DIS_RESET|DIS_TIMER);
	else
		dcmsetischeme(brd, DIS_RESET|DIS_PERCHAR);
	dcm->dcm_mdmmsk = MI_CD;	/* enable modem carrier detect intr */
	dcm->dcm_ic = IC_IE;		/* turn all interrupts on */
	/*
	 * Need to reset baud rate, etc. of next print so reset dcmconsole.
	 * Also make sure console is always "hardwired"
	 */
	if (isconsole) {
		dcmconsole = -1;
		dcmsoftCAR[brd] |= (1 << PORT(dcmconsole));
	}
	return (1);
}

dcmopen(dev, flag)
	dev_t dev;
{
	register struct tty *tp;
	register int unit, brd;
	int error;

	unit = UNIT(dev);
	brd = BOARD(unit);
	if (unit >= NDCMLINE || (dcm_active & (1 << brd)) == 0)
		return (ENXIO);
#ifdef KGDB
	if (unit == UNIT(kgdb_dev))
		return (EBUSY);
#endif
	tp = &dcm_tty[unit];
	tp->t_oproc = dcmstart;
	tp->t_param = dcmparam;
	tp->t_dev = dev;
	if ((tp->t_state & TS_ISOPEN) == 0) {
		ttychars(tp);
		tp->t_iflag = TTYDEF_IFLAG;
		tp->t_oflag = TTYDEF_OFLAG;
		tp->t_cflag = TTYDEF_CFLAG;
		tp->t_lflag = TTYDEF_LFLAG;
		tp->t_ispeed = tp->t_ospeed = TTYDEF_SPEED;
		(void) dcmparam(tp, &tp->t_termios);
		ttsetwater(tp);
	} else if (tp->t_state&TS_XCLUDE && u.u_uid != 0)
		return (EBUSY);
	if (PORT(unit) == 0)	/* enable port 0 */
		(void) dcmmctl(dev, MO_ON, DMSET);
	if (dcmsoftCAR[brd] & (1 << PORT(unit)))
		tp->t_state |= TS_CARR_ON;
	else if (PORT(unit))		/* Only port 0 has modem control */
		tp->t_state |= TS_CARR_ON;
	else if (dcmmctl(dev, MO_OFF, DMGET) & MI_CD)
		tp->t_state |= TS_CARR_ON;
	(void) spltty();
	while (!(flag&O_NONBLOCK) && !(tp->t_cflag&CLOCAL) &&
	       (tp->t_state & TS_CARR_ON) == 0) {
		tp->t_state |= TS_WOPEN;
		if ((error = tsleep((caddr_t)&tp->t_rawq, TTIPRI | PCATCH,
				   ttopen, 0)) ||
		    (error = ttclosed(tp))) {
			tp->t_state &= ~TS_WOPEN;
			(void) spl0();
			return (error);
		}
	}
	(void) spl0();

#ifdef DEBUG
	if (dcmdebug & DDB_OPENCLOSE)
		printf("dcmopen: u %x st %x fl %x\n",
			unit, tp->t_state, tp->t_flags);
#endif
	return ((*linesw[tp->t_line].l_open)(dev, tp));
}

/*ARGSUSED*/
dcmclose(dev, flag)
	dev_t dev;
{
	register struct tty *tp;
	int unit;

	unit = UNIT(dev);
	tp = &dcm_tty[unit];
	(*linesw[tp->t_line].l_close)(tp);
	if (tp->t_cflag&HUPCL || tp->t_state&TS_WOPEN ||
	    (tp->t_state&TS_ISOPEN) == 0)
		(void) dcmmctl(dev, MO_OFF, DMSET);
#ifdef DEBUG
	if (dcmdebug & DDB_OPENCLOSE)
		printf("dcmclose: u %x st %x fl %x\n",
			unit, tp->t_state, tp->t_flags);
#endif
	ttyclose(tp);
	return(0);
}

dcmread(dev, uio, flag)
	dev_t dev;
	struct uio *uio;
{
	register struct tty *tp;

	tp = &dcm_tty[UNIT(dev)];
	return ((*linesw[tp->t_line].l_read)(tp, uio, flag));
}

dcmwrite(dev, uio, flag)
	dev_t dev;
	struct uio *uio;
{
	int unit = UNIT(dev);
	register struct tty *tp;

	tp = &dcm_tty[unit];
	/*
	 * XXX we disallow virtual consoles if the physical console is
	 * a serial port.  This is in case there is a display attached that
	 * is not the console.  In that situation we don't need/want the X
	 * server taking over the console.
	 */
	if (constty && unit == dcmconsole)
		constty = NULL;
	return ((*linesw[tp->t_line].l_write)(tp, uio, flag));
}

dcmintr(brd)
	register int brd;
{
	register struct dcmdevice *dcm = dcm_addr[brd];
	register struct dcmischeme *dis;
	int i, code, pcnd[4], mcnd, delta;

	/*
	 * Do all guarded register accesses right off to minimize
	 * block out of hardware.
	 */
	SEM_LOCK(dcm);
	if ((dcm->dcm_ic & IC_IR) == 0) {
		SEM_UNLOCK(dcm);
		return(0);
	}
	for (i = 0; i < 4; i++) {
		pcnd[i] = dcm->dcm_icrtab[i].dcm_data;
		dcm->dcm_icrtab[i].dcm_data = 0;
	}
	mcnd = dcm->dcm_mdmin;
	code = dcm->dcm_iir & IIR_MASK;
	dcm->dcm_iir = 0;	/* XXX doc claims read clears interrupt?! */
	SEM_UNLOCK(dcm);

#ifdef DEBUG
	if (dcmdebug & DDB_INTR)
		printf("dcmintr(%d): iir %x p0 %x p1 %x p2 %x p3 %x m %x\n",
		       brd, code, pcnd[0], pcnd[1], pcnd[2], pcnd[3], mcnd);
#endif
	if (code & IIR_TIMEO)
		dcmrint(brd, dcm);
	if (code & IIR_PORT0)
		dcmpint(MKUNIT(brd, 0), pcnd[0], dcm);
	if (code & IIR_PORT1)
		dcmpint(MKUNIT(brd, 1), pcnd[1],  dcm);
	if (code & IIR_PORT2)
		dcmpint(MKUNIT(brd, 2), pcnd[2], dcm);
	if (code & IIR_PORT3)
		dcmpint(MKUNIT(brd, 3), pcnd[3], dcm);
	if (code & IIR_MODM)
		dcmmint(MKUNIT(brd, 0), mcnd, dcm);	/* always port 0 */

	dis = &dcmischeme[brd];
	/*
	 * Chalk up a receiver interrupt if the timer running or one of
	 * the ports reports a special character interrupt.
	 */
	if ((code & IIR_TIMEO) ||
	    ((pcnd[0]|pcnd[1]|pcnd[2]|pcnd[3]) & IT_SPEC))
		dis->dis_intr++;
	/*
	 * See if it is time to check/change the interrupt rate.
	 */
	if (dcmistype < 0 &&
	    (delta = time.tv_sec - dis->dis_time) >= dcminterval) {
		/*
		 * If currently per-character and averaged over 70 interrupts
		 * per-second (66 is threshold of 600 baud) in last interval,
		 * switch to timer mode.
		 *
		 * XXX decay counts ala load average to avoid spikes?
		 */
		if (dis->dis_perchar && dis->dis_intr > 70 * delta)
			dcmsetischeme(brd, DIS_TIMER);
		/*
		 * If currently using timer and had more interrupts than
		 * received characters in the last interval, switch back
		 * to per-character.  Note that after changing to per-char
		 * we must process any characters already in the queue
		 * since they may have arrived before the bitmap was setup.
		 *
		 * XXX decay counts?
		 */
		else if (!dis->dis_perchar && dis->dis_intr > dis->dis_char) {
			dcmsetischeme(brd, DIS_PERCHAR);
			dcmrint(brd, dcm);
		}
		dis->dis_intr = dis->dis_char = 0;
		dis->dis_time = time.tv_sec;
	}
	return(1);
}

/*
 *  Port interrupt.  Can be two things:
 *	First, it might be a special character (exception interrupt);
 *	Second, it may be a buffer empty (transmit interrupt);
 */
dcmpint(unit, code, dcm)
	int unit, code;
	struct dcmdevice *dcm;
{
	struct tty *tp = &dcm_tty[unit];

	if (code & IT_SPEC)
		dcmreadbuf(unit, dcm, tp);
	if (code & IT_TX)
		dcmxint(unit, dcm, tp);
}

dcmrint(brd, dcm)
	int brd;
	register struct dcmdevice *dcm;
{
	register int i, unit;
	register struct tty *tp;

	unit = MKUNIT(brd, 0);
	tp = &dcm_tty[unit];
	for (i = 0; i < 4; i++, tp++, unit++)
		dcmreadbuf(unit, dcm, tp);
}

dcmreadbuf(unit, dcm, tp)
	int unit;
	register struct dcmdevice *dcm;
	register struct tty *tp;
{
	int port = PORT(unit);
	register struct dcmpreg *pp = dcm_preg(dcm, port);
	register struct dcmrfifo *fifo;
	register int c, stat;
	register unsigned head;
	int nch = 0;
#ifdef IOSTATS
	struct dcmstats *dsp = &dcmstats[BOARD(unit)];

	dsp->rints++;
#endif
	/*
	 * TS_WOPEN catches a race when switching to polling mode from dcmrint
	 */
	if ((tp->t_state & (TS_ISOPEN|TS_WOPEN)) == 0) {
#ifdef KGDB
		if (unit == UNIT(kgdb_dev) &&
		    (head = pp->r_head & RX_MASK) != (pp->r_tail & RX_MASK) &&
		    dcm->dcm_rfifos[3-port][head>>1].data_char == '!') {
			pp->r_head = (head + 2) & RX_MASK;
			printf("kgdb trap from dcm%d\n", unit);
			/* trap into kgdb */
			asm("trap #15;");
			return;
		}
#endif
		pp->r_head = pp->r_tail & RX_MASK;
		return;
	}

	head = pp->r_head & RX_MASK;
	fifo = &dcm->dcm_rfifos[3-port][head>>1];
	/*
	 * XXX upper bound on how many chars we will take in one swallow?
	 */
	while (head != (pp->r_tail & RX_MASK)) {
		/*
		 * Get character/status and update head pointer as fast
		 * as possible to make room for more characters.
		 */
		c = fifo->data_char;
		stat = fifo->data_stat;
		head = (head + 2) & RX_MASK;
		pp->r_head = head;
		fifo = head ? fifo+1 : &dcm->dcm_rfifos[3-port][0];
		nch++;

#ifdef DEBUG
		if (dcmdebug & DDB_INPUT)
			printf("dcmreadbuf(%d): c%x('%c') s%x f%x h%x t%x\n",
			       unit, c&0xFF, c, stat&0xFF,
			       tp->t_flags, head, pp->r_tail);
#endif
		/*
		 * Check for and handle errors
		 */
		if (stat & RD_MASK) {
#ifdef DEBUG
			if (dcmdebug & (DDB_INPUT|DDB_SIOERR))
				printf("dcmreadbuf(%d): err: c%x('%c') s%x\n",
				       unit, stat, c&0xFF, c);
#endif
			if (stat & (RD_BD | RD_FE))
				c |= TTY_FE;
			else if (stat & RD_PE)
				c |= TTY_PE;
			else if (stat & RD_OVF)
				log(LOG_WARNING,
				    "dcm%d: silo overflow\n", unit);
			else if (stat & RD_OE)
				log(LOG_WARNING,
				    "dcm%d: uart overflow\n", unit);
		}
		(*linesw[tp->t_line].l_rint)(c, tp);
	}
	dcmischeme[BOARD(unit)].dis_char += nch;
#ifdef IOSTATS
	dsp->rchars += nch;
	if (nch <= DCMRBSIZE)
		dsp->rsilo[nch]++;
	else
		dsp->rsilo[DCMRBSIZE+1]++;
#endif
}

dcmxint(unit, dcm, tp)
	int unit;
	struct dcmdevice *dcm;
	register struct tty *tp;
{
	tp->t_state &= ~TS_BUSY;
	if (tp->t_state & TS_FLUSH)
		tp->t_state &= ~TS_FLUSH;
	if (tp->t_line)
		(*linesw[tp->t_line].l_start)(tp);
	else
		dcmstart(tp);
}

dcmmint(unit, mcnd, dcm)
	register int unit;
	register struct dcmdevice *dcm;
        int mcnd;
{
	register struct tty *tp;

#ifdef DEBUG
	if (dcmdebug & DDB_MODEM)
		printf("dcmmint: unit %x mcnd %x\n", unit, mcnd);
#endif
	tp = &dcm_tty[unit];
	if ((dcmsoftCAR[BOARD(unit)] & (1 << PORT(unit))) == 0) {
		if (mcnd & MI_CD)
			(void) (*linesw[tp->t_line].l_modem)(tp, 1);
		else if ((*linesw[tp->t_line].l_modem)(tp, 0) == 0) {
			dcm->dcm_mdmout &= ~(MO_DTR | MO_RTS);
			SEM_LOCK(dcm);
			dcm->dcm_cr |= CR_MODM;
			SEM_UNLOCK(dcm);
			DELAY(10); /* time to change lines */
		}
	}
}

dcmioctl(dev, cmd, data, flag)
	dev_t dev;
	caddr_t data;
{
	register struct tty *tp;
	register int unit = UNIT(dev);
	register struct dcmdevice *dcm;
	register int port;
	int error, s;

#ifdef DEBUG
	if (dcmdebug & DDB_IOCTL)
		printf("dcmioctl: unit %d cmd %x data %x flag %x\n",
		       unit, cmd, *data, flag);
#endif
	tp = &dcm_tty[unit];
	error = (*linesw[tp->t_line].l_ioctl)(tp, cmd, data, flag);
	if (error >= 0)
		return (error);
	error = ttioctl(tp, cmd, data, flag);
	if (error >= 0)
		return (error);

	port = PORT(unit);
	dcm = dcm_addr[BOARD(unit)];
	switch (cmd) {
	case TIOCSBRK:
		/*
		 * Wait for transmitter buffer to empty
		 */
		s = spltty();
		while (dcm->dcm_thead[port].ptr != dcm->dcm_ttail[port].ptr)
			DELAY(DCM_USPERCH(tp->t_ospeed));
		SEM_LOCK(dcm);
		dcm->dcm_cmdtab[port].dcm_data |= CT_BRK;
		dcm->dcm_cr |= (1 << port);	/* start break */
		SEM_UNLOCK(dcm);
		splx(s);
		break;

	case TIOCCBRK:
		SEM_LOCK(dcm);
		dcm->dcm_cmdtab[port].dcm_data |= CT_BRK;
		dcm->dcm_cr |= (1 << port);	/* end break */
		SEM_UNLOCK(dcm);
		break;

	case TIOCSDTR:
		(void) dcmmctl(dev, MO_ON, DMBIS);
		break;

	case TIOCCDTR:
		(void) dcmmctl(dev, MO_ON, DMBIC);
		break;

	case TIOCMSET:
		(void) dcmmctl(dev, *(int *)data, DMSET);
		break;

	case TIOCMBIS:
		(void) dcmmctl(dev, *(int *)data, DMBIS);
		break;

	case TIOCMBIC:
		(void) dcmmctl(dev, *(int *)data, DMBIC);
		break;

	case TIOCMGET:
		*(int *)data = dcmmctl(dev, 0, DMGET);
		break;

	default:
		return (ENOTTY);
	}
	return (0);
}

dcmparam(tp, t)
	register struct tty *tp;
	register struct termios *t;
{
	register struct dcmdevice *dcm;
	register int port, mode, cflag = t->c_cflag;
	int ospeed = ttspeedtab(t->c_ospeed, dcmspeedtab);

	/* check requested parameters */
        if (ospeed < 0 || (t->c_ispeed && t->c_ispeed != t->c_ospeed))
                return(EINVAL);
        /* and copy to tty */
        tp->t_ispeed = t->c_ispeed;
        tp->t_ospeed = t->c_ospeed;
        tp->t_cflag = cflag;
	if (ospeed == 0) {
		(void) dcmmctl(UNIT(tp->t_dev), MO_OFF, DMSET);
		return(0);
	}

	mode = 0;
	switch (cflag&CSIZE) {
	case CS5:
		mode = LC_5BITS; break;
	case CS6:
		mode = LC_6BITS; break;
	case CS7:
		mode = LC_7BITS; break;
	case CS8:
		mode = LC_8BITS; break;
	}
	if (cflag&PARENB) {
		if (cflag&PARODD)
			mode |= LC_PODD;
		else
			mode |= LC_PEVEN;
	}
	if (cflag&CSTOPB)
		mode |= LC_2STOP;
	else
		mode |= LC_1STOP;
#ifdef DEBUG
	if (dcmdebug & DDB_PARAM)
		printf("dcmparam(%d): cflag %x mode %x speed %d uperch %d\n",
		       UNIT(tp->t_dev), cflag, mode, tp->t_ospeed,
		       DCM_USPERCH(tp->t_ospeed));
#endif

	port = PORT(tp->t_dev);
	dcm = dcm_addr[BOARD(tp->t_dev)];
	/*
	 * Wait for transmitter buffer to empty.
	 */
	while (dcm->dcm_thead[port].ptr != dcm->dcm_ttail[port].ptr)
		DELAY(DCM_USPERCH(tp->t_ospeed));
	/*
	 * Make changes known to hardware.
	 */
	dcm->dcm_data[port].dcm_baud = ospeed;
	dcm->dcm_data[port].dcm_conf = mode;
	SEM_LOCK(dcm);
	dcm->dcm_cmdtab[port].dcm_data |= CT_CON;
	dcm->dcm_cr |= (1 << port);
	SEM_UNLOCK(dcm);
	/*
	 * Delay for config change to take place. Weighted by buad.
	 * XXX why do we do this?
	 */
	DELAY(16 * DCM_USPERCH(tp->t_ospeed));
	return(0);
}

dcmstart(tp)
	register struct tty *tp;
{
	register struct dcmdevice *dcm;
	register struct dcmpreg *pp;
	register struct dcmtfifo *fifo;
	register char *bp;
	register unsigned tail, next;
	register int port, nch;
	unsigned head;
	char buf[16];
	int s;
#ifdef IOSTATS
	struct dcmstats *dsp = &dcmstats[BOARD(tp->t_dev)];
	int tch = 0;
#endif

	s = spltty();
#ifdef IOSTATS
	dsp->xints++;
#endif
#ifdef DEBUG
	if (dcmdebug & DDB_OUTPUT)
		printf("dcmstart(%d): state %x flags %x outcc %d\n",
		       UNIT(tp->t_dev), tp->t_state, tp->t_flags,
		       tp->t_outq.c_cc);
#endif
	if (tp->t_state & (TS_TIMEOUT|TS_BUSY|TS_TTSTOP))
		goto out;
	if (tp->t_outq.c_cc <= tp->t_lowat) {
		if (tp->t_state&TS_ASLEEP) {
			tp->t_state &= ~TS_ASLEEP;
			wakeup((caddr_t)&tp->t_outq);
		}
		if (tp->t_wsel) {
			selwakeup(tp->t_wsel, tp->t_state & TS_WCOLL);
			tp->t_wsel = 0;
			tp->t_state &= ~TS_WCOLL;
		}
	}
	if (tp->t_outq.c_cc == 0) {
#ifdef IOSTATS
		dsp->xempty++;
#endif
		goto out;
	}

	dcm = dcm_addr[BOARD(tp->t_dev)];
	port = PORT(tp->t_dev);
	pp = dcm_preg(dcm, port);
	tail = pp->t_tail & TX_MASK;
	next = (tail + 1) & TX_MASK;
	head = pp->t_head & TX_MASK;
	if (head == next)
		goto out;
	fifo = &dcm->dcm_tfifos[3-port][tail];
again:
	nch = q_to_b(&tp->t_outq, buf, (head - next) & TX_MASK);
#ifdef IOSTATS
	tch += nch;
#endif
#ifdef DEBUG
	if (dcmdebug & DDB_OUTPUT)
		printf("\thead %x tail %x nch %d\n", head, tail, nch);
#endif
	/*
	 * Loop transmitting all the characters we can.
	 */
	for (bp = buf; --nch >= 0; bp++) {
		fifo->data_char = *bp;
		pp->t_tail = next;
		/*
		 * If this is the first character,
		 * get the hardware moving right now.
		 */
		if (bp == buf) {
			tp->t_state |= TS_BUSY;
			SEM_LOCK(dcm);
			dcm->dcm_cmdtab[port].dcm_data |= CT_TX;
			dcm->dcm_cr |= (1 << port);
			SEM_UNLOCK(dcm);
		}
		tail = next;
		fifo = tail ? fifo+1 : &dcm->dcm_tfifos[3-port][0];
		next = (next + 1) & TX_MASK;
	}
	/*
	 * Head changed while we were loading the buffer,
	 * go back and load some more if we can.
	 */
	if (tp->t_outq.c_cc && head != (pp->t_head & TX_MASK)) {
#ifdef IOSTATS
		dsp->xrestarts++;
#endif
		head = pp->t_head & TX_MASK;
		goto again;
	}
	/*
	 * Kick it one last time in case it finished while we were
	 * loading the last time.
	 */
	if (bp > &buf[1]) {
		tp->t_state |= TS_BUSY;
		SEM_LOCK(dcm);
		dcm->dcm_cmdtab[port].dcm_data |= CT_TX;
		dcm->dcm_cr |= (1 << port);
		SEM_UNLOCK(dcm);
	}
#ifdef DEBUG
	if (dcmdebug & DDB_INTR)
		printf("dcmstart(%d): head %x tail %x outqcc %d ch %d\n",
		       UNIT(tp->t_dev), head, tail, tp->t_outq.c_cc, tch);
#endif
out:
#ifdef IOSTATS
	dsp->xchars += tch;
	if (tch <= DCMXBSIZE)
		dsp->xsilo[tch]++;
	else
		dsp->xsilo[DCMXBSIZE+1]++;
#endif
	splx(s);
}

/*
 * Stop output on a line.
 */
dcmstop(tp, flag)
	register struct tty *tp;
{
	int s;

	s = spltty();
	if (tp->t_state & TS_BUSY) {
		/* XXX is there some way to safely stop transmission? */
		if ((tp->t_state&TS_TTSTOP)==0)
			tp->t_state |= TS_FLUSH;
	}
	splx(s);
}

/* Modem control */

dcmmctl(dev, bits, how)
	dev_t dev;
	int bits, how;
{
	register struct dcmdevice *dcm;
	int s, hit = 0;

	/*
	 * Only port 0 has modem control lines.
	 * XXX ok for now but needs to changed for the 8 port board.
	 */
	if (PORT(UNIT(dev)) != 0)
		return(bits);

	dcm = dcm_addr[BOARD(UNIT(dev))];
	s = spltty();
	switch (how) {

	case DMSET:
		dcm->dcm_mdmout = bits;
		hit++;
		break;

	case DMBIS:
		dcm->dcm_mdmout |= bits;
		hit++;
		break;

	case DMBIC:
		dcm->dcm_mdmout &= ~bits;
		hit++;
		break;

	case DMGET:
		bits = dcm->dcm_mdmin;
		break;
	}
	if (hit) {
		SEM_LOCK(dcm);
		dcm->dcm_cr |= CR_MODM;
		SEM_UNLOCK(dcm);
		DELAY(10); /* delay until done */
		(void) splx(s);
	}
	return(bits);
}

/*
 * Set board to either interrupt per-character or at a fixed interval.
 */
dcmsetischeme(brd, flags)
	int brd, flags;
{
	register struct dcmdevice *dcm = dcm_addr[brd];
	register struct dcmischeme *dis = &dcmischeme[brd];
	register int i;
	u_char mask;
	int perchar = flags & DIS_PERCHAR;

#ifdef DEBUG
	if (dcmdebug & DDB_INTSCHM)
		printf("dcmsetischeme(%d, %d): cur %d, ints %d, chars %d\n",
		       brd, perchar, dis->dis_perchar,
		       dis->dis_intr, dis->dis_char);
	if ((flags & DIS_RESET) == 0 && perchar == dis->dis_perchar) {
		printf("dcmsetischeme(%d):  redundent request %d\n",
		       brd, perchar);
		return;
	}
#endif
	/*
	 * If perchar is non-zero, we enable interrupts on all characters
	 * otherwise we disable perchar interrupts and use periodic
	 * polling interrupts.
	 */
	dis->dis_perchar = perchar;
	mask = perchar ? 0xf : 0x0;
	for (i = 0; i < 256; i++)
		dcm->dcm_bmap[i].data_data = mask;
	/*
	 * Don't slow down tandem mode, interrupt on flow control
	 * chars for any port on the board.
	 */
	if (!perchar) {
		register struct tty *tp = &dcm_tty[MKUNIT(brd, 0)];
		int c;

		for (i = 0; i < 4; i++, tp++) {
			if ((c = tp->t_cc[VSTART]) != _POSIX_VDISABLE)
				dcm->dcm_bmap[c].data_data |= (1 << i);
			if ((c = tp->t_cc[VSTOP]) != _POSIX_VDISABLE)
				dcm->dcm_bmap[c].data_data |= (1 << i);
		}
	}
	/*
	 * Board starts with timer disabled so if first call is to
	 * set perchar mode then we don't want to toggle the timer.
	 */
	if (flags == (DIS_RESET|DIS_PERCHAR))
		return;
	/*
	 * Toggle card 16.7ms interrupts (we first make sure that card
	 * has cleared the bit so it will see the toggle).
	 */
	while (dcm->dcm_cr & CR_TIMER)
		;
	SEM_LOCK(dcm);
	dcm->dcm_cr |= CR_TIMER;
	SEM_UNLOCK(dcm);
}

/*
 * Following are all routines needed for DCM to act as console
 */
#include "machine/cons.h"

dcmcnprobe(cp)
	struct consdev *cp;
{
	register struct hp_hw *hw;
	int unit, i;
	extern int dcmopen();

	/*
	 * Implicitly assigns the lowest select code DCM card found to be
	 * logical unit 0 (actually CONUNIT).  If your config file does
	 * anything different, you're screwed.
	 */
	for (hw = sc_table; hw->hw_type; hw++)
	        if (hw->hw_type == COMMDCM && !badaddr((short *)hw->hw_addr))
			break;
	if (hw->hw_type != COMMDCM) {
		cp->cn_pri = CN_DEAD;
		return;
	}
	unit = CONUNIT;
	dcm_addr[BOARD(CONUNIT)] = (struct dcmdevice *)hw->hw_addr;

	/* locate the major number */
	for (i = 0; i < nchrdev; i++)
		if (cdevsw[i].d_open == dcmopen)
			break;

	/* initialize required fields */
	cp->cn_dev = makedev(i, unit);
	cp->cn_tp = &dcm_tty[unit];
	switch (dcm_addr[BOARD(unit)]->dcm_rsid) {
	case DCMID:
		cp->cn_pri = CN_NORMAL;
		break;
	case DCMID|DCMCON:
		cp->cn_pri = CN_REMOTE;
		break;
	default:
		cp->cn_pri = CN_DEAD;
		break;
	}
}

dcmcninit(cp)
	struct consdev *cp;
{
	dcminit(cp->cn_dev, dcmdefaultrate);
	dcmconsole = UNIT(cp->cn_dev);
}

dcminit(dev, rate)
	dev_t dev;
	int rate;
{
	register struct dcmdevice *dcm = dcm_addr[BOARD(dev)];
	int s, mode, port;

	port = PORT(dev);
	mode = LC_8BITS | LC_1STOP;
	s = splhigh();
	/*
	 * Wait for transmitter buffer to empty.
	 */
	while (dcm->dcm_thead[port].ptr != dcm->dcm_ttail[port].ptr)
		DELAY(DCM_USPERCH(rate));
	/*
	 * Make changes known to hardware.
	 */
	dcm->dcm_data[port].dcm_baud = ttspeedtab(rate, dcmspeedtab);
	dcm->dcm_data[port].dcm_conf = mode;
	SEM_LOCK(dcm);
	dcm->dcm_cmdtab[port].dcm_data |= CT_CON;
	dcm->dcm_cr |= (1 << port);
	SEM_UNLOCK(dcm);
	/*
	 * Delay for config change to take place. Weighted by buad.
	 * XXX why do we do this?
	 */
	DELAY(16 * DCM_USPERCH(rate));
	splx(s);
}

dcmcngetc(dev)
	dev_t dev;
{
	register struct dcmdevice *dcm = dcm_addr[BOARD(dev)];
	register struct dcmrfifo *fifo;
	register struct dcmpreg *pp;
	register unsigned head;
	int s, c, stat, port;

	port = PORT(dev);
	pp = dcm_preg(dcm, port);
	s = splhigh();
	head = pp->r_head & RX_MASK;
	fifo = &dcm->dcm_rfifos[3-port][head>>1];
	while (head == (pp->r_tail & RX_MASK))
		;
	/*
	 * If board interrupts are enabled, just let our received char
	 * interrupt through in case some other port on the board was
	 * busy.  Otherwise we must clear the interrupt.
	 */
	SEM_LOCK(dcm);
	if ((dcm->dcm_ic & IC_IE) == 0)
		stat = dcm->dcm_iir;
	SEM_UNLOCK(dcm);
	c = fifo->data_char;
	stat = fifo->data_stat;
	pp->r_head = (head + 2) & RX_MASK;
	splx(s);
	return(c);
}

/*
 * Console kernel output character routine.
 */
dcmcnputc(dev, c)
	dev_t dev;
	int c;
{
	register struct dcmdevice *dcm = dcm_addr[BOARD(dev)];
	register struct dcmpreg *pp;
	unsigned tail;
	int s, port, stat;

	port = PORT(dev);
	pp = dcm_preg(dcm, port);
	s = splhigh();
#ifdef KGDB
	if (dev != kgdb_dev)
#endif
	if (dcmconsole == -1) {
		(void) dcminit(dev, dcmdefaultrate);
		dcmconsole = UNIT(dev);
	}
	tail = pp->t_tail & TX_MASK;
	while (tail != (pp->t_head & TX_MASK))
		;
	dcm->dcm_tfifos[3-port][tail].data_char = c;
	pp->t_tail = tail = (tail + 1) & TX_MASK;
	SEM_LOCK(dcm);
	dcm->dcm_cmdtab[port].dcm_data |= CT_TX;
	dcm->dcm_cr |= (1 << port);
	SEM_UNLOCK(dcm);
	while (tail != (pp->t_head & TX_MASK))
		;
	/*
	 * If board interrupts are enabled, just let our completion
	 * interrupt through in case some other port on the board
	 * was busy.  Otherwise we must clear the interrupt.
	 */
	if ((dcm->dcm_ic & IC_IE) == 0) {
		SEM_LOCK(dcm);
		stat = dcm->dcm_iir;
		SEM_UNLOCK(dcm);
	}
	splx(s);
}
#endif