xref: /csrg-svn/sys/hp/dev/dca.c (revision 52389)
1 /*
2  * Copyright (c) 1982, 1986, 1990 The Regents of the University of California.
3  * All rights reserved.
4  *
5  * %sccs.include.redist.c%
6  *
7  *	@(#)dca.c	7.13 (Berkeley) 02/05/92
8  */
9 
10 #include "dca.h"
11 #if NDCA > 0
12 /*
13  *  98626/98644/internal serial interface
14  *  uses National Semiconductor INS8250/NS16550AF UART
15  */
16 #include "sys/param.h"
17 #include "sys/systm.h"
18 #include "sys/ioctl.h"
19 #include "sys/tty.h"
20 #include "sys/proc.h"
21 #include "sys/conf.h"
22 #include "sys/file.h"
23 #include "sys/uio.h"
24 #include "sys/kernel.h"
25 #include "sys/syslog.h"
26 
27 #include "device.h"
28 #include "dcareg.h"
29 #include "machine/cpu.h"
30 #include "../hp300/isr.h"
31 
32 int	dcaprobe();
33 struct	driver dcadriver = {
34 	dcaprobe, "dca",
35 };
36 
37 void	dcastart();
38 int	dcaparam(), dcaintr();
39 int	dcasoftCAR;
40 int	dca_active;
41 int	dca_hasfifo;
42 int	ndca = NDCA;
43 #ifdef DCACONSOLE
44 int	dcaconsole = DCACONSOLE;
45 #else
46 int	dcaconsole = -1;
47 #endif
48 int	dcaconsinit;
49 int	dcadefaultrate = TTYDEF_SPEED;
50 int	dcamajor;
51 struct	dcadevice *dca_addr[NDCA];
52 struct	tty dca_tty[NDCA];
53 struct	isr dcaisr[NDCA];
54 
55 struct speedtab dcaspeedtab[] = {
56 	0,	0,
57 	50,	DCABRD(50),
58 	75,	DCABRD(75),
59 	110,	DCABRD(110),
60 	134,	DCABRD(134),
61 	150,	DCABRD(150),
62 	200,	DCABRD(200),
63 	300,	DCABRD(300),
64 	600,	DCABRD(600),
65 	1200,	DCABRD(1200),
66 	1800,	DCABRD(1800),
67 	2400,	DCABRD(2400),
68 	4800,	DCABRD(4800),
69 	9600,	DCABRD(9600),
70 	19200,	DCABRD(19200),
71 	38400,	DCABRD(38400),
72 	-1,	-1
73 };
74 
75 extern	struct tty *constty;
76 #ifdef KGDB
77 #include "machine/remote-sl.h"
78 
79 extern dev_t kgdb_dev;
80 extern int kgdb_rate;
81 extern int kgdb_debug_init;
82 #endif
83 
84 #define	UNIT(x)		minor(x)
85 
86 #ifdef DEBUG
87 long	fifoin[17];
88 long	fifoout[17];
89 long	dcaintrcount[16];
90 long	dcamintcount[16];
91 #endif
92 
93 dcaprobe(hd)
94 	register struct hp_device *hd;
95 {
96 	register struct dcadevice *dca;
97 	register int unit;
98 
99 	dca = (struct dcadevice *)hd->hp_addr;
100 	if (dca->dca_irid != DCAID0 &&
101 	    dca->dca_irid != DCAREMID0 &&
102 	    dca->dca_irid != DCAID1 &&
103 	    dca->dca_irid != DCAREMID1)
104 		return (0);
105 	unit = hd->hp_unit;
106 	if (unit == dcaconsole)
107 		DELAY(100000);
108 	dca->dca_irid = 0xFF;
109 	DELAY(100);
110 
111 	/* look for a NS 16550AF UART with FIFOs */
112 	dca->dca_fifo = FIFO_ENABLE|FIFO_RCV_RST|FIFO_XMT_RST|FIFO_TRIGGER_14;
113 	DELAY(100);
114 	if ((dca->dca_iir & IIR_FIFO_MASK) == IIR_FIFO_MASK)
115 		dca_hasfifo |= 1 << unit;
116 
117 	hd->hp_ipl = DCAIPL(dca->dca_ic);
118 	dcaisr[unit].isr_ipl = hd->hp_ipl;
119 	dcaisr[unit].isr_arg = unit;
120 	dcaisr[unit].isr_intr = dcaintr;
121 	dca_addr[unit] = dca;
122 	dca_active |= 1 << unit;
123 	dcasoftCAR = hd->hp_flags;
124 	isrlink(&dcaisr[unit]);
125 #ifdef KGDB
126 	if (kgdb_dev == makedev(dcamajor, unit)) {
127 		if (dcaconsole == unit)
128 			kgdb_dev = NODEV; /* can't debug over console port */
129 		else {
130 			(void) dcainit(unit, kgdb_rate);
131 			dcaconsinit = 1;	/* don't re-init in dcaputc */
132 			if (kgdb_debug_init) {
133 				/*
134 				 * Print prefix of device name,
135 				 * let kgdb_connect print the rest.
136 				 */
137 				printf("dca%d: ", unit);
138 				kgdb_connect(1);
139 			} else
140 				printf("dca%d: kgdb enabled\n", unit);
141 		}
142 	}
143 #endif
144 	dca->dca_ic = IC_IE;
145 	/*
146 	 * Need to reset baud rate, etc. of next print so reset dcaconsinit.
147 	 * Also make sure console is always "hardwired."
148 	 */
149 	if (unit == dcaconsole) {
150 		dcaconsinit = 0;
151 		dcasoftCAR |= (1 << unit);
152 	}
153 	return (1);
154 }
155 
156 /* ARGSUSED */
157 #ifdef __STDC__
158 dcaopen(dev_t dev, int flag, int mode, struct proc *p)
159 #else
160 dcaopen(dev, flag, mode, p)
161 	dev_t dev;
162 	int flag, mode;
163 	struct proc *p;
164 #endif
165 {
166 	register struct tty *tp;
167 	register int unit;
168 	int error = 0;
169 
170 	unit = UNIT(dev);
171 	if (unit >= NDCA || (dca_active & (1 << unit)) == 0)
172 		return (ENXIO);
173 	tp = &dca_tty[unit];
174 	tp->t_oproc = dcastart;
175 	tp->t_param = dcaparam;
176 	tp->t_dev = dev;
177 	if ((tp->t_state & TS_ISOPEN) == 0) {
178 		tp->t_state |= TS_WOPEN;
179 		ttychars(tp);
180 		if (tp->t_ispeed == 0) {
181 			tp->t_iflag = TTYDEF_IFLAG;
182 			tp->t_oflag = TTYDEF_OFLAG;
183 			tp->t_cflag = TTYDEF_CFLAG;
184 			tp->t_lflag = TTYDEF_LFLAG;
185 			tp->t_ispeed = tp->t_ospeed = dcadefaultrate;
186 		}
187 		dcaparam(tp, &tp->t_termios);
188 		ttsetwater(tp);
189 	} else if (tp->t_state&TS_XCLUDE && p->p_ucred->cr_uid != 0)
190 		return (EBUSY);
191 	(void) dcamctl(dev, MCR_DTR | MCR_RTS, DMSET);
192 	if ((dcasoftCAR & (1 << unit)) || (dcamctl(dev, 0, DMGET) & MSR_DCD))
193 		tp->t_state |= TS_CARR_ON;
194 	(void) spltty();
195 	while ((flag&O_NONBLOCK) == 0 && (tp->t_cflag&CLOCAL) == 0 &&
196 	       (tp->t_state & TS_CARR_ON) == 0) {
197 		tp->t_state |= TS_WOPEN;
198 		if (error = ttysleep(tp, (caddr_t)&tp->t_rawq, TTIPRI | PCATCH,
199 		    ttopen, 0))
200 			break;
201 	}
202 	(void) spl0();
203 	if (error == 0)
204 		error = (*linesw[tp->t_line].l_open)(dev, tp);
205 	return (error);
206 }
207 
208 /*ARGSUSED*/
209 dcaclose(dev, flag, mode, p)
210 	dev_t dev;
211 	int flag, mode;
212 	struct proc *p;
213 {
214 	register struct tty *tp;
215 	register struct dcadevice *dca;
216 	register int unit;
217 
218 	unit = UNIT(dev);
219 	dca = dca_addr[unit];
220 	tp = &dca_tty[unit];
221 	(*linesw[tp->t_line].l_close)(tp, flag);
222 	dca->dca_cfcr &= ~CFCR_SBREAK;
223 #ifdef KGDB
224 	/* do not disable interrupts if debugging */
225 	if (dev != kgdb_dev)
226 #endif
227 	dca->dca_ier = 0;
228 	if (tp->t_cflag&HUPCL || tp->t_state&TS_WOPEN ||
229 	    (tp->t_state&TS_ISOPEN) == 0)
230 		(void) dcamctl(dev, 0, DMSET);
231 	ttyclose(tp);
232 	return (0);
233 }
234 
235 dcaread(dev, uio, flag)
236 	dev_t dev;
237 	struct uio *uio;
238 {
239 	register struct tty *tp = &dca_tty[UNIT(dev)];
240 
241 	return ((*linesw[tp->t_line].l_read)(tp, uio, flag));
242 }
243 
244 dcawrite(dev, uio, flag)
245 	dev_t dev;
246 	struct uio *uio;
247 {
248 	int unit = UNIT(dev);
249 	register struct tty *tp = &dca_tty[unit];
250 
251 	/*
252 	 * (XXX) We disallow virtual consoles if the physical console is
253 	 * a serial port.  This is in case there is a display attached that
254 	 * is not the console.  In that situation we don't need/want the X
255 	 * server taking over the console.
256 	 */
257 	if (constty && unit == dcaconsole)
258 		constty = NULL;
259 	return ((*linesw[tp->t_line].l_write)(tp, uio, flag));
260 }
261 
262 dcaintr(unit)
263 	register int unit;
264 {
265 	register struct dcadevice *dca;
266 	register u_char code;
267 	register struct tty *tp;
268 
269 	dca = dca_addr[unit];
270 	if ((dca->dca_ic & IC_IR) == 0)
271 		return (0);
272 	while (1) {
273 		code = dca->dca_iir;
274 #ifdef DEBUG
275 		dcaintrcount[code & IIR_IMASK]++;
276 #endif
277 		switch (code & IIR_IMASK) {
278 		case IIR_NOPEND:
279 			return (1);
280 		case IIR_RXTOUT:
281 		case IIR_RXRDY:
282 			/* do time-critical read in-line */
283 			tp = &dca_tty[unit];
284 /*
285  * Process a received byte.  Inline for speed...
286  */
287 #ifdef KGDB
288 #define	RCVBYTE() \
289 			code = dca->dca_data; \
290 			if ((tp->t_state & TS_ISOPEN) == 0) { \
291 				if (code == FRAME_END && \
292 				    kgdb_dev == makedev(dcamajor, unit)) \
293 					kgdb_connect(0); /* trap into kgdb */ \
294 			} else \
295 				(*linesw[tp->t_line].l_rint)(code, tp)
296 #else
297 #define	RCVBYTE() \
298 			code = dca->dca_data; \
299 			if ((tp->t_state & TS_ISOPEN) != 0) \
300 				(*linesw[tp->t_line].l_rint)(code, tp)
301 #endif
302 			RCVBYTE();
303 			if (dca_hasfifo & (1 << unit)) {
304 #ifdef DEBUG
305 				register int fifocnt = 1;
306 #endif
307 				while ((code = dca->dca_lsr) & LSR_RCV_MASK) {
308 					if (code == LSR_RXRDY) {
309 						RCVBYTE();
310 					} else
311 						dcaeint(unit, code, dca);
312 #ifdef DEBUG
313 					fifocnt++;
314 #endif
315 				}
316 #ifdef DEBUG
317 				if (fifocnt > 16)
318 					fifoin[0]++;
319 				else
320 					fifoin[fifocnt]++;
321 #endif
322 			}
323 			break;
324 		case IIR_TXRDY:
325 			tp = &dca_tty[unit];
326 			tp->t_state &=~ (TS_BUSY|TS_FLUSH);
327 			if (tp->t_line)
328 				(*linesw[tp->t_line].l_start)(tp);
329 			else
330 				dcastart(tp);
331 			break;
332 		case IIR_RLS:
333 			dcaeint(unit, dca->dca_lsr, dca);
334 			break;
335 		default:
336 			if (code & IIR_NOPEND)
337 				return (1);
338 			log(LOG_WARNING, "dca%d: weird interrupt: 0x%x\n",
339 			    unit, code);
340 			/* fall through */
341 		case IIR_MLSC:
342 			dcamint(unit, dca);
343 			break;
344 		}
345 	}
346 }
347 
348 dcaeint(unit, stat, dca)
349 	register int unit, stat;
350 	register struct dcadevice *dca;
351 {
352 	register struct tty *tp;
353 	register int c;
354 
355 	tp = &dca_tty[unit];
356 	c = dca->dca_data;
357 	if ((tp->t_state & TS_ISOPEN) == 0) {
358 #ifdef KGDB
359 		/* we don't care about parity errors */
360 		if (((stat & (LSR_BI|LSR_FE|LSR_PE)) == LSR_PE) &&
361 		    kgdb_dev == makedev(dcamajor, unit) && c == FRAME_END)
362 			kgdb_connect(0); /* trap into kgdb */
363 #endif
364 		return;
365 	}
366 	if (stat & (LSR_BI | LSR_FE))
367 		c |= TTY_FE;
368 	else if (stat & LSR_PE)
369 		c |= TTY_PE;
370 	else if (stat & LSR_OE)
371 		log(LOG_WARNING, "dca%d: silo overflow\n", unit);
372 	(*linesw[tp->t_line].l_rint)(c, tp);
373 }
374 
375 dcamint(unit, dca)
376 	register int unit;
377 	register struct dcadevice *dca;
378 {
379 	register struct tty *tp;
380 	register int stat;
381 
382 	tp = &dca_tty[unit];
383 	stat = dca->dca_msr;
384 #ifdef DEBUG
385 	dcamintcount[stat & 0xf]++;
386 #endif
387 	if ((stat & MSR_DDCD) && (dcasoftCAR & (1 << unit)) == 0) {
388 		if (stat & MSR_DCD)
389 			(void)(*linesw[tp->t_line].l_modem)(tp, 1);
390 		else if ((*linesw[tp->t_line].l_modem)(tp, 0) == 0)
391 			dca->dca_mcr &= ~(MCR_DTR | MCR_RTS);
392 	} else if ((stat & MSR_DCTS) && (tp->t_state & TS_ISOPEN) &&
393 		   (tp->t_flags & CRTSCTS)) {
394 		/* the line is up and we want to do rts/cts flow control */
395 		if (stat & MSR_CTS) {
396 			tp->t_state &=~ TS_TTSTOP;
397 			ttstart(tp);
398 		} else
399 			tp->t_state |= TS_TTSTOP;
400 	}
401 }
402 
403 dcaioctl(dev, cmd, data, flag)
404 	dev_t dev;
405 	caddr_t data;
406 {
407 	register struct tty *tp;
408 	register int unit = UNIT(dev);
409 	register struct dcadevice *dca;
410 	register int error;
411 
412 	tp = &dca_tty[unit];
413 	error = (*linesw[tp->t_line].l_ioctl)(tp, cmd, data, flag);
414 	if (error >= 0)
415 		return (error);
416 	error = ttioctl(tp, cmd, data, flag);
417 	if (error >= 0)
418 		return (error);
419 
420 	dca = dca_addr[unit];
421 	switch (cmd) {
422 
423 	case TIOCSBRK:
424 		dca->dca_cfcr |= CFCR_SBREAK;
425 		break;
426 
427 	case TIOCCBRK:
428 		dca->dca_cfcr &= ~CFCR_SBREAK;
429 		break;
430 
431 	case TIOCSDTR:
432 		(void) dcamctl(dev, MCR_DTR | MCR_RTS, DMBIS);
433 		break;
434 
435 	case TIOCCDTR:
436 		(void) dcamctl(dev, MCR_DTR | MCR_RTS, DMBIC);
437 		break;
438 
439 	case TIOCMSET:
440 		(void) dcamctl(dev, *(int *)data, DMSET);
441 		break;
442 
443 	case TIOCMBIS:
444 		(void) dcamctl(dev, *(int *)data, DMBIS);
445 		break;
446 
447 	case TIOCMBIC:
448 		(void) dcamctl(dev, *(int *)data, DMBIC);
449 		break;
450 
451 	case TIOCMGET:
452 		*(int *)data = dcamctl(dev, 0, DMGET);
453 		break;
454 
455 	default:
456 		return (ENOTTY);
457 	}
458 	return (0);
459 }
460 
461 dcaparam(tp, t)
462 	register struct tty *tp;
463 	register struct termios *t;
464 {
465 	register struct dcadevice *dca;
466 	register int cfcr, cflag = t->c_cflag;
467 	int unit = UNIT(tp->t_dev);
468 	int ospeed = ttspeedtab(t->c_ospeed, dcaspeedtab);
469 
470 	/* check requested parameters */
471         if (ospeed < 0 || (t->c_ispeed && t->c_ispeed != t->c_ospeed))
472                 return (EINVAL);
473         /* and copy to tty */
474         tp->t_ispeed = t->c_ispeed;
475         tp->t_ospeed = t->c_ospeed;
476         tp->t_cflag = cflag;
477 
478 	dca = dca_addr[unit];
479 	dca->dca_ier = IER_ERXRDY | IER_ETXRDY | IER_ERLS | IER_EMSC;
480 	if (ospeed == 0) {
481 		(void) dcamctl(unit, 0, DMSET);	/* hang up line */
482 		return (0);
483 	}
484 	dca->dca_cfcr |= CFCR_DLAB;
485 	dca->dca_data = ospeed & 0xFF;
486 	dca->dca_ier = ospeed >> 8;
487 	switch (cflag&CSIZE) {
488 	case CS5:
489 		cfcr = CFCR_5BITS; break;
490 	case CS6:
491 		cfcr = CFCR_6BITS; break;
492 	case CS7:
493 		cfcr = CFCR_7BITS; break;
494 	case CS8:
495 		cfcr = CFCR_8BITS; break;
496 	}
497 	if (cflag&PARENB) {
498 		cfcr |= CFCR_PENAB;
499 		if ((cflag&PARODD) == 0)
500 			cfcr |= CFCR_PEVEN;
501 	}
502 	if (cflag&CSTOPB)
503 		cfcr |= CFCR_STOPB;
504 	dca->dca_cfcr = cfcr;
505 	if (dca_hasfifo & (1 << unit))
506 		dca->dca_fifo = FIFO_ENABLE | FIFO_TRIGGER_14;
507 	return (0);
508 }
509 
510 void
511 dcastart(tp)
512 	register struct tty *tp;
513 {
514 	register struct dcadevice *dca;
515 	int s, unit, c;
516 
517 	unit = UNIT(tp->t_dev);
518 	dca = dca_addr[unit];
519 	s = spltty();
520 	if (tp->t_state & (TS_TIMEOUT|TS_TTSTOP))
521 		goto out;
522 	if (tp->t_outq.c_cc <= tp->t_lowat) {
523 		if (tp->t_state&TS_ASLEEP) {
524 			tp->t_state &= ~TS_ASLEEP;
525 			wakeup((caddr_t)&tp->t_outq);
526 		}
527 		if (tp->t_wsel) {
528 			selwakeup(tp->t_wsel, tp->t_state & TS_WCOLL);
529 			tp->t_wsel = 0;
530 			tp->t_state &= ~TS_WCOLL;
531 		}
532 	}
533 	if (tp->t_outq.c_cc == 0)
534 		goto out;
535 	if (dca->dca_lsr & LSR_TXRDY) {
536 		c = getc(&tp->t_outq);
537 		tp->t_state |= TS_BUSY;
538 		dca->dca_data = c;
539 		if (dca_hasfifo & (1 << unit)) {
540 			for (c = 1; c < 16 && tp->t_outq.c_cc; ++c)
541 				dca->dca_data = getc(&tp->t_outq);
542 #ifdef DEBUG
543 			if (c > 16)
544 				fifoout[0]++;
545 			else
546 				fifoout[c]++;
547 #endif
548 		}
549 	}
550 out:
551 	splx(s);
552 }
553 
554 /*
555  * Stop output on a line.
556  */
557 /*ARGSUSED*/
558 dcastop(tp, flag)
559 	register struct tty *tp;
560 {
561 	register int s;
562 
563 	s = spltty();
564 	if (tp->t_state & TS_BUSY) {
565 		if ((tp->t_state&TS_TTSTOP)==0)
566 			tp->t_state |= TS_FLUSH;
567 	}
568 	splx(s);
569 }
570 
571 dcamctl(dev, bits, how)
572 	dev_t dev;
573 	int bits, how;
574 {
575 	register struct dcadevice *dca;
576 	register int unit;
577 	int s;
578 
579 	unit = UNIT(dev);
580 	dca = dca_addr[unit];
581 	s = spltty();
582 	switch (how) {
583 
584 	case DMSET:
585 		dca->dca_mcr = bits;
586 		break;
587 
588 	case DMBIS:
589 		dca->dca_mcr |= bits;
590 		break;
591 
592 	case DMBIC:
593 		dca->dca_mcr &= ~bits;
594 		break;
595 
596 	case DMGET:
597 		bits = dca->dca_msr;
598 		break;
599 	}
600 	(void) splx(s);
601 	return (bits);
602 }
603 
604 /*
605  * Following are all routines needed for DCA to act as console
606  */
607 #include "../hp300/cons.h"
608 
609 dcacnprobe(cp)
610 	struct consdev *cp;
611 {
612 	int unit;
613 
614 	/* locate the major number */
615 	for (dcamajor = 0; dcamajor < nchrdev; dcamajor++)
616 		if (cdevsw[dcamajor].d_open == dcaopen)
617 			break;
618 
619 	/* XXX: ick */
620 	unit = CONUNIT;
621 	dca_addr[CONUNIT] = (struct dcadevice *) sctova(CONSCODE);
622 
623 	/* make sure hardware exists */
624 	if (badaddr((short *)dca_addr[unit])) {
625 		cp->cn_pri = CN_DEAD;
626 		return;
627 	}
628 
629 	/* initialize required fields */
630 	cp->cn_dev = makedev(dcamajor, unit);
631 	cp->cn_tp = &dca_tty[unit];
632 	switch (dca_addr[unit]->dca_irid) {
633 	case DCAID0:
634 	case DCAID1:
635 		cp->cn_pri = CN_NORMAL;
636 		break;
637 	case DCAREMID0:
638 	case DCAREMID1:
639 		cp->cn_pri = CN_REMOTE;
640 		break;
641 	default:
642 		cp->cn_pri = CN_DEAD;
643 		break;
644 	}
645 	/*
646 	 * If dcaconsole is initialized, raise our priority.
647 	 */
648 	if (dcaconsole == unit)
649 		cp->cn_pri = CN_REMOTE;
650 #ifdef KGDB
651 	if (major(kgdb_dev) == 1)			/* XXX */
652 		kgdb_dev = makedev(dcamajor, minor(kgdb_dev));
653 #endif
654 }
655 
656 dcacninit(cp)
657 	struct consdev *cp;
658 {
659 	int unit = UNIT(cp->cn_dev);
660 
661 	dcainit(unit, dcadefaultrate);
662 	dcaconsole = unit;
663 	dcaconsinit = 1;
664 }
665 
666 dcainit(unit, rate)
667 	int unit, rate;
668 {
669 	register struct dcadevice *dca;
670 	int s;
671 	short stat;
672 
673 #ifdef lint
674 	stat = unit; if (stat) return;
675 #endif
676 	dca = dca_addr[unit];
677 	s = splhigh();
678 	dca->dca_irid = 0xFF;
679 	DELAY(100);
680 	dca->dca_ic = IC_IE;
681 	dca->dca_cfcr = CFCR_DLAB;
682 	rate = ttspeedtab(rate, dcaspeedtab);
683 	dca->dca_data = rate & 0xFF;
684 	dca->dca_ier = rate >> 8;
685 	dca->dca_cfcr = CFCR_8BITS;
686 	dca->dca_ier = IER_ERXRDY | IER_ETXRDY;
687 	dca->dca_fifo = FIFO_ENABLE|FIFO_RCV_RST|FIFO_XMT_RST|FIFO_TRIGGER_14;
688 	stat = dca->dca_iir;
689 	splx(s);
690 }
691 
692 dcacngetc(dev)
693 {
694 	register struct dcadevice *dca = dca_addr[UNIT(dev)];
695 	short stat;
696 	int c, s;
697 
698 #ifdef lint
699 	stat = dev; if (stat) return (0);
700 #endif
701 	s = splhigh();
702 	while (((stat = dca->dca_lsr) & LSR_RXRDY) == 0)
703 		;
704 	c = dca->dca_data;
705 	stat = dca->dca_iir;
706 	splx(s);
707 	return (c);
708 }
709 
710 /*
711  * Console kernel output character routine.
712  */
713 dcacnputc(dev, c)
714 	dev_t dev;
715 	register int c;
716 {
717 	register struct dcadevice *dca = dca_addr[UNIT(dev)];
718 	register int timo;
719 	short stat;
720 	int s = splhigh();
721 
722 #ifdef lint
723 	stat = dev; if (stat) return;
724 #endif
725 	if (dcaconsinit == 0) {
726 		(void) dcainit(UNIT(dev), dcadefaultrate);
727 		dcaconsinit = 1;
728 	}
729 	/* wait for any pending transmission to finish */
730 	timo = 50000;
731 	while (((stat = dca->dca_lsr) & LSR_TXRDY) == 0 && --timo)
732 		;
733 	dca->dca_data = c;
734 	/* wait for this transmission to complete */
735 	timo = 1500000;
736 	while (((stat = dca->dca_lsr) & LSR_TXRDY) == 0 && --timo)
737 		;
738 	/* clear any interrupts generated by this transmission */
739 	stat = dca->dca_iir;
740 	splx(s);
741 }
742 #endif
743