xref: /netbsd-src/sys/arch/sgimips/dev/scn.c (revision b610ccb0d6fb85d0833c5ef7e784b0e8a2d210bb)
1 /*	$NetBSD: scn.c,v 1.1 2009/02/10 06:04:56 rumble Exp $ */
2 
3 /*
4  * Resurrected from the old pc532 port 1/18/2009.
5  *
6  * XXX- The locking in this is probably totally broken. I haven't attempted
7  *      to get it right, but it seems to work okay anyhow.
8  */
9 
10 /*
11  * Copyright (c) 1991, 1992, 1993
12  *	The Regents of the University of California.  All rights reserved.
13  *
14  * Portions of this software were developed by the Computer Systems
15  * Engineering group at Lawrence Berkeley Laboratory under DARPA
16  * contract BG 91-66 and contributed to Berkeley.
17  *
18  * All advertising materials mentioning features or use of this software
19  * must display the following acknowledgement:
20  *	This product includes software developed by the University of
21  *	California, Lawrence Berkeley Laboratory.
22  *
23  * Redistribution and use in source and binary forms, with or without
24  * modification, are permitted provided that the following conditions
25  * are met:
26  * 1. Redistributions of source code must retain the above copyright
27  *    notice, this list of conditions and the following disclaimer.
28  * 2. Redistributions in binary form must reproduce the above copyright
29  *    notice, this list of conditions and the following disclaimer in the
30  *    documentation and/or other materials provided with the distribution.
31  * 3. Neither the name of the University nor the names of its contributors
32  *    may be used to endorse or promote products derived from this software
33  *    without specific prior written permission.
34  *
35  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
36  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
37  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
38  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
39  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
40  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
41  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
42  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
43  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
44  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
45  * SUCH DAMAGE.
46  *
47  *	from: @(#)com.c	7.5 (Berkeley) 5/16/91
48  */
49 
50 /*
51  * Copyright (c) 1996, 1997 Philip L. Budne.
52  * Copyright (c) 1993 Philip A. Nelson.
53  *
54  * Portions of this software were developed by the Computer Systems
55  * Engineering group at Lawrence Berkeley Laboratory under DARPA
56  * contract BG 91-66 and contributed to Berkeley.
57  *
58  * All advertising materials mentioning features or use of this software
59  * must display the following acknowledgement:
60  *	This product includes software developed by the University of
61  *	California, Lawrence Berkeley Laboratory.
62  *
63  * Redistribution and use in source and binary forms, with or without
64  * modification, are permitted provided that the following conditions
65  * are met:
66  * 1. Redistributions of source code must retain the above copyright
67  *    notice, this list of conditions and the following disclaimer.
68  * 2. Redistributions in binary form must reproduce the above copyright
69  *    notice, this list of conditions and the following disclaimer in the
70  *    documentation and/or other materials provided with the distribution.
71  * 3. All advertising materials mentioning features or use of this software
72  *    must display the following acknowledgement:
73  *	This product includes software developed by the University of
74  *	California, Berkeley and its contributors.
75  * 4. Neither the name of the University nor the names of its contributors
76  *    may be used to endorse or promote products derived from this software
77  *    without specific prior written permission.
78  *
79  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
80  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
81  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
82  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
83  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
84  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
85  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
86  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
87  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
88  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
89  * SUCH DAMAGE.
90  *
91  *	from: @(#)com.c	7.5 (Berkeley) 5/16/91
92  */
93 
94 #include <sys/cdefs.h>
95 __KERNEL_RCSID(0, "$NetBSD: scn.c,v 1.1 2009/02/10 06:04:56 rumble Exp $");
96 
97 #include "opt_ddb.h"
98 #include "opt_kgdb.h"
99 #include "scn.h"
100 
101 #include <sys/param.h>
102 #include <sys/systm.h>
103 #include <sys/ioctl.h>
104 #include <sys/select.h>
105 #include <sys/tty.h>
106 #include <sys/proc.h>
107 #include <sys/user.h>
108 #include <sys/file.h>
109 #include <sys/uio.h>
110 #include <sys/kernel.h>
111 #include <sys/syslog.h>
112 #include <sys/types.h>
113 #include <sys/device.h>
114 #include <sys/malloc.h>
115 #include <sys/conf.h>
116 #include <sys/intr.h>
117 #ifdef KGDB
118 #include <sys/kgdb.h>
119 #endif
120 #include <sys/kauth.h>
121 
122 #include <dev/cons.h>
123 
124 #include <machine/autoconf.h>
125 #include <machine/machtype.h>
126 
127 #include <sgimips/dev/scnreg.h>
128 #include <sgimips/dev/scnvar.h>
129 
130 int     scn_match(device_t, struct cfdata *, void *);
131 void    scn_attach(device_t, device_t, void *);
132 int     scnparam(struct tty *, struct termios *);
133 void    scnstart(struct tty *);
134 int     scnhwiflow(struct tty *, int);
135 
136 void	scncnprobe(struct consdev *);
137 void	scncninit(struct consdev *);
138 int     scncngetc(dev_t);
139 void    scncnputc(dev_t, int);
140 void	scncnpollc(dev_t, int);
141 int	scninit(dev_t, int);
142 void	scncnreinit(void *);
143 
144 CFATTACH_DECL(scn, sizeof(struct scn_softc),
145     scn_match, scn_attach, NULL, NULL);
146 
147 extern struct cfdriver scn_cd;
148 
149 dev_type_open(scnopen);
150 dev_type_close(scnclose);
151 dev_type_read(scnread);
152 dev_type_write(scnwrite);
153 dev_type_ioctl(scnioctl);
154 dev_type_stop(scnstop);
155 dev_type_tty(scntty);
156 dev_type_poll(scnpoll);
157 
158 const struct cdevsw scn_cdevsw = {
159 	scnopen, scnclose, scnread, scnwrite, scnioctl,
160 	scnstop, scntty, scnpoll, nommap, ttykqfilter, D_TTY
161 };
162 
163 struct consdev scn_cn = {
164 	scncnprobe,
165 	scncninit,
166 	scncngetc,
167 	scncnputc,
168 	scncnpollc,
169 	NULL,
170 	NULL,
171 	NULL,
172 	NODEV,
173 	CN_NORMAL
174 };
175 
176 #ifndef CONSOLE_SPEED
177 #define CONSOLE_SPEED TTYDEF_SPEED
178 #endif
179 
180 #ifndef SCNDEF_CFLAG
181 #define SCNDEF_CFLAG TTYDEF_CFLAG
182 #endif
183 
184 #ifdef CPU30MHZ
185 #define RECOVER()	__asm volatile("bispsrw 0x800" : : : "cc")
186 #else
187 #define RECOVER()
188 #endif
189 
190 int     scndefaultrate = TTYDEF_SPEED;
191 int     scnconsrate = CONSOLE_SPEED;
192 
193 static inline struct scn_softc *
194 SOFTC(int unit)
195 {
196 	if (unit < 0 || unit >= scn_cd.cd_ndevs)
197 		return (NULL);
198 	return ((struct scn_softc *)scn_cd.cd_devs[unit]);
199 }
200 
201 static int	scnintr(void *);
202 static void	scnrxintr(void *);
203 static int	scn_rxintr(struct scn_softc *);
204 static void	scnsoft(void *);
205 static void	scn_setchip(struct scn_softc *sc);
206 static int	scniter(int *, int, int*, int*, struct chan *, int);
207 static int	scn_config(int, int, int, int, u_char, u_char);
208 static void	scn_rxenable(struct scn_softc *);
209 static void	scn_rxdisable(struct scn_softc *);
210 static void	dcd_int(struct scn_softc *, struct tty *, u_char);
211 static void	scnoverrun(int, long *, const char *);
212 static u_char	opbits(struct scn_softc *, int);
213 
214 static void *scnsir = NULL;		/* s/w intr cookie */
215 #define setsoftscn()	softint_schedule(scnsir)
216 
217 #ifdef SCN_TIMING
218 /*
219  * Keep timing info on latency of software interrupt used by
220  * the ringbuf code to empty ring buffer.
221  * "getinfo" program reads data from /dev/kmem.
222  */
223 static struct timeval tstart;
224 #define NJITTER 100
225 int     scn_njitter = NJITTER;
226 int     scn_jitter[NJITTER];
227 #endif
228 
229 #define SCN_CLOCK	3686400		/* input clock */
230 
231 /* speed table groups ACR[7] */
232 #define GRP_A	0
233 #define GRP_B	ACR_BRG
234 
235 /* combo of MR0[2:0] and ACR[7] */
236 #define MODE0A	MR0_MODE_0
237 #define MODE0B	(MR0_MODE_0|ACR_BRG)
238 #define MODE1A	MR0_MODE_1
239 #define MODE1B	(MR0_MODE_1|ACR_BRG)
240 #define MODE2A	MR0_MODE_2
241 #define MODE2B	(MR0_MODE_2|ACR_BRG)
242 
243 #define ANYMODE	-1
244 #define DEFMODE(C92) MODE0A		/* use MODE4A if 26c92? */
245 
246 /* speed code for Counter/Timer (all modes, groups) */
247 #define USE_CT 0xd
248 
249 /*
250  * Rate table, ordered by speed, then mode.
251  * NOTE: ordering of modes must be done carefully!
252  */
253 struct tabent {
254 	int32_t speed;
255 	int16_t code;
256 	int16_t mode;
257 } table[] = {
258 	{     50, 0x0, MODE0A },
259 	{     75, 0x0, MODE0B },
260 	{    110, 0x1, MODE0A },
261 	{    110, 0x1, MODE0B },
262 	{    110, 0x1, MODE1A },
263 	{    110, 0x1, MODE1B },
264 	{    134, 0x2, MODE0A },	/* 134.5 */
265 	{    134, 0x2, MODE0B },	/* 134.5 */
266 	{    134, 0x2, MODE1A },	/* 134.5 */
267 	{    134, 0x2, MODE1B },	/* 134.5 */
268 	{    150, 0x3, MODE0A },
269 	{    150, 0x3, MODE0A },
270 	{    200, 0x3, MODE0A },
271 	{    300, 0x4, MODE0A },
272 	{    300, 0x4, MODE0B },
273 	{    300, 0x0, MODE1A },
274 	{    450, 0x0, MODE1B },
275 	{    600, 0x5, MODE0A },
276 	{    600, 0x5, MODE0B },
277 	{    880, 0x1, MODE2A },
278 	{    880, 0x1, MODE2B },
279 	{    900, 0x3, MODE1B },
280 	{   1050, 0x7, MODE0A },
281 	{   1050, 0x7, MODE1A },
282 	{   1076, 0x2, MODE2A },
283 	{   1076, 0x2, MODE2B },
284 	{   1200, 0x6, MODE0A },
285 	{   1200, 0x6, MODE0B },
286 	{   1200, 0x3, MODE1A },
287 	{   1800, 0xa, MODE0B },
288 	{   1800, 0x4, MODE1A },
289 	{   1800, 0x4, MODE1B },
290 	{   2000, 0x7, MODE0B },
291 	{   2000, 0x7, MODE1B },
292 	{   2400, 0x8, MODE0A },
293 	{   2400, 0x8, MODE0B },
294 	{   3600, 0x5, MODE1A },
295 	{   3600, 0x5, MODE1B },
296 	{   4800, 0x9, MODE2A },
297 	{   4800, 0x9, MODE2B },
298 	{   4800, 0x9, MODE0A },
299 	{   4800, 0x9, MODE0B },
300 	{   7200, 0xa, MODE0A },
301 	{   7200, 0x0, MODE2B },
302 	{   7200, 0x6, MODE1A },
303 	{   7200, 0x6, MODE1B },
304 	{   9600, 0xb, MODE2A },
305 	{   9600, 0xb, MODE2B },
306 	{   9600, 0xb, MODE0A },
307 	{   9600, 0xb, MODE0B },
308 	{   9600, 0xd, MODE1A },	/* use C/T as entre' to mode1 */
309 	{   9600, 0xd, MODE1B },	/* use C/T as entre' to mode1 */
310 	{  14400, 0x3, MODE2B },
311 	{  14400, 0x8, MODE1A },
312 	{  14400, 0x8, MODE1B },
313 	{  19200, 0x3, MODE2A },
314 	{  19200, 0xc, MODE2B },
315 	{  19200, 0xc, MODE0B },
316 	{  19200, 0xd, MODE1A },	/* use C/T as entre' to mode1 */
317 	{  19200, 0xd, MODE1B },	/* use C/T as entre' to mode1 */
318 	{  28800, 0x4, MODE2A },
319 	{  28800, 0x4, MODE2B },
320 	{  28800, 0x9, MODE1A },
321 	{  28800, 0x9, MODE1B },
322 	{  38400, 0xc, MODE2A },
323 	{  38400, 0xc, MODE0A },
324 	{  57600, 0x5, MODE2A },
325 	{  57600, 0x5, MODE2B },
326 	{  57600, 0xb, MODE1A },
327 	{  57600, 0xb, MODE1B },
328 	{ 115200, 0x6, MODE2A },
329 	{ 115200, 0x6, MODE2B },
330 	{ 115200, 0xc, MODE1B },
331 	{ 230400, 0xc, MODE1A }
332 };
333 #define TABENTRIES (sizeof(table)/sizeof(table[0]))
334 
335 /*
336  * boolean for speed codes which are identical in both A/B BRG groups
337  * in all modes
338  */
339 static u_char bothgroups[16] = {
340 	0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 0, 1, 0, 1, 1, 1
341 };
342 
343 /*
344  * Manually constructed divisors table
345  * for minimum error (from some of Dave Rand's code)
346  */
347 const struct {
348 	uint16_t speed;
349 	uint16_t div;
350 } divs[] = {
351 	{    50, 2303 },	/* 2304 is exact?? */
352 	{   110, 1047 },	/* Should be 1047.27 */
353 	{   134, 857 },		/* Should be 856.505576 */
354 	{  1050, 110 },		/* Should be 109.7142857 */
355 	{  2000, 57 }		/* Should be 57.6 */
356 };
357 #define DIVS (sizeof(divs)/sizeof(divs[0]))
358 
359 /*
360  * minor unit bit decode:
361  * CxxxUUU
362  *
363  * C - carrier
364  *	0 - delay open until carrier high
365  *	1 - allow open with carrier low
366  * UUU - unit 0-7
367  */
368 
369 #define DEV_UNIT(x)	(minor(x) & 0x7)
370 #define DEV_DIALOUT(x)	(minor(x) & 0x80)
371 
372 extern struct tty *constty;
373 
374 #define SCN_MAXDUART 4
375 static struct duart scn_duart[SCN_MAXDUART];
376 
377 #ifdef KGDB
378 extern int kgdb_dev;
379 extern int kgdb_rate;
380 extern int kgdb_debug_init;
381 #endif
382 
383 /* XXXXX - fix this */
384 #define splrtty() spltty()
385 
386 /* RS-232 configuration routines */
387 
388 /*
389  * set chip parameters, or mark for delayed change.
390  * called at spltty() or on TxEMPTY interrupt.
391  *
392  * Reads current values to avoid glitches from redundant sets.
393  * Perhaps should save last value set to avoid read/write?  NOTE:
394  * Would still need to do read if write not needed to advance MR
395  * pointer.
396  *
397  * new 2/97 -plb
398  */
399 
400 static void
401 scn_setchip(struct scn_softc *sc)
402 {
403 	struct duart *dp;
404 	u_char acr, csr, mr1, mr2;
405 	int chan;
406 
407 	if (sc->sc_tty && (sc->sc_tty->t_state & TS_BUSY)) {
408 		sc->sc_heldchanges = 1;
409 		return;
410 	}
411 
412 	chan = sc->sc_channel;
413 	dp = sc->sc_duart;
414 	if (dp->type == SC26C92) {
415 		u_char nmr0a, mr0a;
416 
417 		/* input rate high enough so 64 bit time watchdog not
418 		 * onerous? */
419 		if (dp->chan[chan].ispeed >= 1200) {
420 			/* set FIFO threshold at 6 for other
421 			 * thresholds we could have to set MR1_FFULL
422 			 */
423 			dp->chan[chan].mr0 |= MR0_RXWD | MR0_RXINT;
424 		} else {
425 			dp->chan[chan].mr0 &= ~(MR0_RXWD | MR0_RXINT);
426 		}
427 
428 		/* select BRG mode (MR0A only) */
429 		nmr0a = dp->chan[0].mr0 | (dp->mode & MR0_MODE);
430 
431 		dp->base[CH_CR] = CR_CMD_MR0;
432 		RECOVER();
433 
434 		mr0a = dp->base[CH_MR];
435 		if (mr0a != nmr0a) {
436 			dp->base[CH_CR] = CR_CMD_MR0;
437 			RECOVER();
438 			dp->base[CH_MR] = nmr0a;
439 		}
440 
441 		if (chan) {	 /* channel B? */
442 			u_char mr0b;
443 
444 			sc->sc_chbase[CH_CR] = CR_CMD_MR0;
445 			RECOVER();
446 			mr0b = dp->base[CH_MR];
447 
448 			if (dp->chan[chan].mr0 != mr0b) {
449 				sc->sc_chbase[CH_CR] = CR_CMD_MR0;
450 				RECOVER();
451 				sc->sc_chbase[CH_MR] = dp->chan[chan].mr0;
452 			}
453 		}
454 	} else {
455 		sc->sc_chbase[CH_CR] = CR_CMD_MR1;
456 		RECOVER();
457 	}
458 
459 	mr1 = sc->sc_chbase[CH_MR];
460 	mr2 = sc->sc_chbase[CH_MR];
461 	if (mr1 != dp->chan[chan].new_mr1 ||
462 	    mr2 != dp->chan[chan].new_mr2) {
463 		sc->sc_chbase[CH_CR] = CR_CMD_MR1;
464 		RECOVER();
465 		sc->sc_chbase[CH_MR] = dp->chan[chan].new_mr1;
466 		sc->sc_chbase[CH_MR] = dp->chan[chan].new_mr2;
467 	}
468 
469 	acr = dp->acr | (dp->mode & ACR_BRG);
470 	dp->base[DU_ACR] = acr;		/* write-only reg! */
471 
472 	/* set speed codes */
473 	csr = (dp->chan[chan].icode<<4) | dp->chan[chan].ocode;
474 	if (sc->sc_chbase[CH_CSR] != csr) {
475 		sc->sc_chbase[CH_CSR] = csr;
476 	}
477 
478 	/* see if counter/timer in use */
479 	if (dp->counter &&
480 	    (dp->chan[0].icode == USE_CT || dp->chan[0].ocode == USE_CT ||
481 	     dp->chan[1].icode == USE_CT || dp->chan[1].ocode == USE_CT)) {
482 
483 		/* program counter/timer only if necessary */
484 		if (dp->counter != dp->ocounter) {
485 			uint16_t div;
486 #ifdef DIVS
487 			int i;
488 
489 			/* look for precalculated rate, for minimum error */
490 			for (i = 0; i < DIVS && divs[i].speed <= dp->counter; i++) {
491 				if (divs[i].speed == dp->counter) {
492 					div = divs[i].div;
493 					goto found;
494 				}
495 			}
496 #endif
497 
498 			/* not found in table; calculate a value (rounding up) */
499 			div = ((long)SCN_CLOCK/16/2 + dp->counter/2) / dp->counter;
500 
501 		found:
502 			/* halt before loading? may ALWAYS glitch?
503 			 * reload race may only sometimes glitch??
504 			 */
505 			dp->base[DU_CTUR] = div >> 8;
506 			dp->base[DU_CTLR] = div & 255;
507 			if (dp->ocounter == 0) {
508 				/* not previously used? */
509 				u_char temp;
510 				/* start C/T running */
511 				temp = dp->base[DU_CSTRT];
512 			}
513 			dp->ocounter = dp->counter;
514 		}
515 	} else {
516 		/* counter not in use; mark as free */
517 		dp->counter = 0;
518 	}
519 	sc->sc_heldchanges = 0;
520 
521 	/*
522 	 * delay a tiny bit to try and avoid tx glitching.
523 	 * I know we're at spltty(), but this is much better than the
524 	 * old version used DELAY((96000 / out_speed) * 10000)
525 	 * -plb
526 	 */
527 	DELAY(10);
528 }
529 
530 /*
531  * iterator function for speeds.
532  * (could be called "findnextcode")
533  * Returns sequence of possible speed codes for a given rate.
534  * should set index to zero before first call.
535  *
536  * Could be implemented as a "checkspeed()" function called
537  * to evaluate table entries, BUT this allows more variety in
538  * use of C/T with fewer table entries.
539  */
540 
541 static int
542 scniter(int *index, int wanted, int *counter, int *mode, struct chan *other,
543     int c92)
544 {
545 
546 	while (*index < TABENTRIES) {
547 		struct tabent *tp;
548 
549 		tp = table + (*index)++;
550 		if (tp->speed != wanted)
551 			continue;
552 
553 		/* if not a 26C92 only look at MODE0 entries */
554 		if (!c92 && (tp->mode & MR0_MODE) != MR0_MODE_0)
555 			continue;
556 
557 		/*
558 		 * check mode;
559 		 * OK if this table entry for current mode, or mode not
560 		 * yet set, or other channel's rates are available in both
561 		 * A and B groups.
562 		 */
563 
564 		if (tp->mode == *mode || *mode == ANYMODE ||
565 		    (other != NULL && (tp->mode & MR0_MODE) == (*mode & MR0_MODE) &&
566 		     bothgroups[other->icode] && bothgroups[other->ocode])) {
567 			/*
568 			 * for future table entries specifying
569 			 * use of counter/timer
570 			 */
571 			if (tp->code == USE_CT) {
572 				if (*counter != wanted && *counter != 0)
573 					continue;	/* counter busy */
574 				*counter = wanted;
575 			}
576 			*mode = tp->mode;
577 			return tp->code;
578 		}
579 	}
580 
581 	/* here after returning all applicable table entries */
582 	/* XXX return sequence of USE_CT with all possible modes?? */
583 	if ((*index)++ == TABENTRIES) {
584 		/* Max C/T rate (even on 26C92?) is 57600 */
585 		if (wanted <= 57600 && (*counter == wanted || *counter == 0)) {
586 			*counter = wanted;
587 			return USE_CT;
588 		}
589 	}
590 
591 	return -1;			/* FAIL */
592 }
593 
594 /*
595  * calculate configuration
596  * rewritten 2/97 -plb
597  */
598 static int
599 scn_config(int unit, int chan, int ispeed, int ospeed, u_char mr1, u_char mr2)
600 {
601 	struct scn_softc *sc;
602 	struct duart *dp;
603 	int other;		/* opposite of chan */
604 	int mode;
605 	int counter;
606 	int i, o;		/* input, output iterator indexes */
607 	int ic, oc;		/* input, output codes */
608 	struct chan *ocp;	/* other duart channel */
609 	struct tty *otp;	/* other channel tty struct */
610 	int c92;		/* true if duart is sc26c92 */
611 	int s;
612 
613 	/* Set up softc pointer. */
614 	if (unit >= scn_cd.cd_ndevs)
615 		return ENXIO;
616 	sc = SOFTC(unit);
617 	chan = sc->sc_channel;
618 	other = chan ^ 1;
619 	dp = sc->sc_duart;
620 	ocp = &dp->chan[other];
621 	otp = ocp->tty;
622 	c92 = (dp->type == SC26C92);
623 
624 	/*
625 	 * Right now the first combination that works is used.
626 	 * Perhaps it should search entire solution space for "best"
627 	 * combination. For example, use heuristic weighting of mode
628 	 * preferences, and use of counter timer?
629 	 *
630 	 * For example right now with 2681/2692 when default rate is
631 	 * 9600 and other channel is closed setting 19200 will pick
632 	 * mode 0a and use counter/timer.  Better solution might be
633 	 * mode 0b, leaving counter/timer free!
634 	 *
635 	 * When other channel is open might want to prefer
636 	 * leaving counter timer free, or not flipping A/B group?
637 	 */
638 	if (otp && (otp->t_state & TS_ISOPEN)) {
639 
640 		/*
641 		 * Other channel open;
642 		 * Find speed codes compatible with current mode/counter.
643 		 */
644 
645 		i = 0;
646 		for (;;) {
647 			mode = dp->mode;
648 			counter = dp->counter;
649 
650 			/* NOTE: pass other chan pointer to allow group flipping */
651 			ic = scniter(&i, ispeed, &counter, &mode, ocp, c92);
652 			if (ic == -1)
653 				break;
654 
655 			o = 0;
656 			if ((oc = scniter(&o, ospeed, &counter,
657 					  &mode, NULL, c92)) != -1) {
658 				/*
659 				 * take first match
660 				 *
661 				 * Perhaps calculate heuristic "score",
662 				 * save score,codes,mode,counter if score
663 				 * better than previous best?
664 				 */
665 				goto gotit;
666 			}
667 		}
668 		/* XXX try looping for ospeed? */
669 	} else {
670 		/* other channel closed */
671 		int oo, oi;	/* other input, output iterators */
672 		int oic, ooc;	/* other input, output codes */
673 
674 		/*
675 		 * Here when other channel closed.  Finds first
676 		 * combination that will allow other channel to be opened
677 		 * (with defaults) and fits our needs.
678 		 */
679 		oi = 0;
680 		for (;;) {
681 			mode = ANYMODE;
682 			counter = 0;
683 
684 			oic = scniter(&oi, ocp->ispeed, &counter, &mode, NULL, c92);
685 			if (oic == -1)
686 				break;
687 
688 			oo = 0;
689 			while ((ooc = scniter(&oo, ocp->ospeed, &counter,
690 					   &mode, NULL, c92)) != -1) {
691 				i = 0;
692 				while ((ic = scniter(&i, ispeed, &counter,
693 						  &mode, NULL, c92)) != -1) {
694 					o = 0;
695 					if ((oc = scniter(&o, ospeed, &counter,
696 						       &mode, NULL, c92)) != -1) {
697 						/*
698 						 * take first match
699 						 *
700 						 * Perhaps calculate heuristic
701 						 * "score", save
702 						 *     score,codes,mode,counter
703 						 * if score better than
704 						 * previous best?
705 						 */
706 						s = spltty();
707 						dp->chan[other].icode = oic;
708 						dp->chan[other].ocode = ooc;
709 						goto gotit2;
710 					}
711 				}
712 			}
713 		}
714 	}
715 	return EINVAL;
716 
717  gotit:
718 	s = spltty();
719  gotit2:
720 	dp->chan[chan].new_mr1 = mr1;
721 	dp->chan[chan].new_mr2 = mr2;
722 	dp->chan[chan].ispeed = ispeed;
723 	dp->chan[chan].ospeed = ospeed;
724 	dp->chan[chan].icode = ic;
725 	dp->chan[chan].ocode = oc;
726 	if (mode == ANYMODE)		/* no mode selected?? */
727 		mode = DEFMODE(c92);
728 	dp->mode = mode;
729 	dp->counter = counter;
730 
731 	scn_setchip(sc);		/* set chip now, if possible */
732 	splx(s);
733 	return (0);
734 }
735 
736 int
737 scn_match(device_t parent, struct cfdata *cf, void *aux)
738 {
739 	struct mainbus_attach_args *ma = aux;
740 
741 	if ((mach_type == MACH_SGI_IP6 || mach_type == MACH_SGI_IP10) &&
742 	    ma->ma_addr == 0x1fb80004)
743 		return (1);
744 
745 	return (0);
746 }
747 
748 /*
749  * No need to make scn_rx{en,dis}able too efficient,
750  * they're only called on setup, open & close!
751  */
752 static inline void
753 scn_rxenable(struct scn_softc *sc)
754 {
755 	struct duart *dp;
756 	int channel;
757 
758 	dp = sc->sc_duart;
759 	channel = sc->sc_channel;
760 
761 	/* Outputs wire-ored and connected to ICU input for fast rx interrupt. */
762 	if (channel == 0)
763 		dp->opcr |= OPCR_OP4_RXRDYA;
764 	else
765 		dp->opcr |= OPCR_OP5_RXRDYB;
766 	dp->base[DU_OPCR] = dp->opcr;
767 	dp->imr |= sc->sc_rx_int;
768 	dp->base[DU_IMR] = dp->imr;
769 }
770 
771 static inline void
772 scn_rxdisable(struct scn_softc *sc)
773 {
774 	struct duart *dp;
775 	int channel;
776 
777 	dp = sc->sc_duart;
778 	channel = sc->sc_channel;
779 
780 	/* Outputs wire-ored and connected to ICU input for fast rx interrupt. */
781 	if (channel == 0)
782 		dp->opcr &= ~OPCR_OP4_RXRDYA;
783 	else
784 		dp->opcr &= ~OPCR_OP5_RXRDYB;
785 	dp->base[DU_OPCR] = dp->opcr;
786 	dp->imr &= ~sc->sc_rx_int;
787 	dp->base[DU_IMR] = dp->imr;
788 }
789 
790 void
791 scn_attach(device_t parent, device_t self, void *aux)
792 {
793 	struct mainbus_attach_args *ma = aux;
794 	struct scn_softc *sc;
795 	struct duart *duart;
796 	volatile u_char *ch_base;
797 	volatile u_char *duart_base;
798 	int channel;
799 	int speed;
800 	int s;
801 	int maj;
802 	u_char unit;
803 	u_char duartno;
804 	u_char delim = ':';
805 	u_char mr1, mr2;
806 	enum scntype scntype = SCNUNK;
807 	const char *duart_type = "Unknown";
808 	char *intrname;
809 	bool console, first;
810 	devmajor_t major;
811 
812 	(void)major;
813 
814 	sc = device_private(self);
815 	unit = device_unit(self);
816 
817 	/* XXX - hard-coded */
818 	if (ma->ma_addr == 0x1fb80004)
819 		duartno = 1;
820 	else
821 		duartno = 0;
822 	channel = 0;
823 	console = 1;
824 
825 	duart = sc->sc_duart = &scn_duart[duartno];
826 	duart->chan[channel].sc = sc;
827 	first =	(duart->base == NULL);
828 
829 	if (console) {
830 		sc->sc_isconsole = 1;
831 		sc->sc_swflags |= SCN_SW_SOFTCAR;	/* ignore carrier */
832 	}
833 
834 	duart_base = (volatile u_char *)MIPS_PHYS_TO_KSEG1(ma->ma_addr);
835 	ch_base    = duart_base; /* XXX */
836 
837 	if (first) {
838 		/* Probe DUART type */
839 		s = spltty();
840 		if (console) {
841 			ch_base[CH_CR] = CR_DIS_TX;
842 			delay(5 * 10000);
843 		}
844 		ch_base[CH_CR] = CR_CMD_MR1;
845 		RECOVER();
846 		mr1 = ch_base[CH_MR];
847 		mr2 = ch_base[CH_MR];
848 		ch_base[CH_CR] = CR_CMD_MR1;
849 		RECOVER();
850 		ch_base[CH_MR] = 1;
851 		ch_base[CH_MR] = 0;
852 		ch_base[CH_CR] = CR_CMD_MR1;
853 		RECOVER();
854 		if (ch_base[CH_MR] == 1) {
855 			/* MR 2 selected */
856 			ch_base[CH_CR] = CR_CMD_MR0;
857 			RECOVER();
858 			/* if 2681, MR2 still selected */
859 			ch_base[CH_MR] = 1;
860 			ch_base[CH_CR] = CR_CMD_MR1;
861 			RECOVER();
862 			ch_base[CH_MR] = 0; /* MR1 */
863 			ch_base[CH_MR] = 0; /* MR2 */
864 			ch_base[CH_CR] = CR_CMD_MR0;
865 			RECOVER();
866 			/* if 2681, MR2 still selected */
867 			if((ch_base[CH_MR] & 1) == 1) {
868 				duart_type = "sc26c92";
869 				scntype = SC26C92;
870 			} else {
871 				/* 2681 treats as MR1 Select */
872 				ch_base[CH_CR] = CR_CMD_RTS_OFF;
873 				RECOVER();
874 				ch_base[CH_MR] = 1;
875 				ch_base[CH_MR] = 0;
876 				ch_base[CH_CR] = CR_CMD_RTS_OFF;
877 				RECOVER();
878 				if (ch_base[CH_MR] == 1) {
879 					duart_type = "scn2681";
880 					scntype = SCN2681;
881 				} else {
882 					duart_type = "scn2692";
883 					scntype = SCN2692;
884 				}
885 			}
886 		}
887 
888 		/* If a 2681, the CR_CMD_MR0 is interpreted as a TX_RESET */
889 		if (console) {
890 			ch_base[CH_CR] = CR_ENA_TX;
891 			RECOVER();
892 		}
893 		ch_base[CH_CR] = CR_CMD_MR1;
894 		RECOVER();
895 		ch_base[CH_MR] = mr1;
896 		ch_base[CH_MR] = mr2;
897 		splx(s);
898 
899 		intrname = malloc(sizeof("scnXX"), M_DEVBUF, M_NOWAIT);
900 		snprintf(intrname, sizeof("scnXX"), "scn%d", unit);
901 
902 		/*
903 		 * On IP6 the console chip is duart1. The keyboard/mouse
904 		 * is duart0. Each chip has two channels and the channels
905 		 * share an interrupt. Duart0 is interrupt 0, duart1 is
906 		 * interrupt 1.
907 		 */
908 		if (duartno != 0 && duartno != 1)
909 			panic("scn_attach: bad duartno: %d", duartno);
910 		cpu_intr_establish(duartno, IPL_TTY, scnintr, duart);
911 
912 		printf("%c %s", delim, duart_type);
913 		delim = ',';
914 
915 		duart->base = duart_base;
916 		duart->type = scntype;
917 	}
918 	/* Record channel, uart */
919 	sc->sc_channel = channel;
920 	sc->sc_chbase = ch_base;
921 
922 	/* Initialize modem/interrupt bit masks */
923 	if (channel == 0) {
924 		sc->sc_op_rts = OP_RTSA;
925 		sc->sc_op_dtr = OP_DTRA;
926 		sc->sc_ip_cts = IP_CTSA;
927 		sc->sc_ip_dcd = IP_DCDA;
928 
929 		sc->sc_tx_int = INT_TXA;
930 		sc->sc_rx_int = INT_RXA;
931 	} else {
932 		sc->sc_op_rts = OP_RTSB;
933 		sc->sc_op_dtr = OP_DTRB;
934 		sc->sc_ip_cts = IP_CTSB;
935 		sc->sc_ip_dcd = IP_DCDB;
936 
937 		sc->sc_tx_int = INT_TXB;
938 		sc->sc_rx_int = INT_RXB;
939 	}
940 
941 	/* Initialize counters */
942 	sc->sc_framing_errors = 0;
943 	sc->sc_fifo_overruns = 0;
944 	sc->sc_parity_errors = 0;
945 	sc->sc_breaks = 0;
946 
947 	if (console) {
948 		DELAY(5 * 10000);	/* Let the output go out.... */
949 	}
950 
951 	/*
952 	 * Set up the hardware to a base state, in particular:
953 	 * o reset transmitter and receiver
954 	 * o set speeds and configurations
955 	 * o receiver interrupts only (RxRDY and BREAK)
956 	 */
957 
958 	s = spltty();
959 	/* RTS off... */
960 	SCN_OP_BIC(sc, sc->sc_op_rts);	/* "istop" */
961 
962 	ch_base[CH_CR] = CR_DIS_RX | CR_DIS_TX;
963 	RECOVER();
964 	ch_base[CH_CR] = CR_CMD_RESET_RX;
965 	RECOVER();
966 	ch_base[CH_CR] = CR_CMD_RESET_TX;
967 	RECOVER();
968 	ch_base[CH_CR] = CR_CMD_RESET_ERR;
969 	RECOVER();
970 	ch_base[CH_CR] = CR_CMD_RESET_BRK;
971 	RECOVER();
972 	ch_base[CH_CR] = CR_CMD_MR1;
973 	RECOVER();
974 
975 	/* No receiver control of RTS. */
976 	ch_base[CH_MR] = 0;
977 	ch_base[CH_MR] = 0;
978 
979 	/* Initialize the uart structure if this is channel A. */
980 	if (first) {
981 		/* Disable all interrupts. */
982 		duart_base[DU_IMR] = duart->imr = 0;
983 
984 		/* Output port config */
985 		duart_base[DU_OPCR] = duart->opcr = 0;
986 
987 		/* Speeds... */
988 		duart->mode = 0;
989 
990 		/*
991 		 * Set initial speed to an illegal code that can be changed to
992 		 * any other baud.
993 		 */
994 		duart->chan[0].icode = duart->chan[0].ocode = 0x2f;
995 		duart->chan[1].icode = duart->chan[1].ocode = 0x2f;
996 		duart->chan[0].ispeed = duart->chan[0].ospeed = 0;
997 		duart->chan[1].ispeed = duart->chan[1].ospeed = 0;
998 
999 		duart->acr = 0;
1000 		duart->acr |= ACR_CT_TCLK1;	/* timer mode 1x clk */
1001 	}
1002 
1003 	if (channel == 0) {
1004 		duart->acr |= ACR_DELTA_DCDA;	/* Set CD int */
1005 	} else {
1006 		duart->acr |= ACR_DELTA_DCDB;	/* Set CD int */
1007 	}
1008 
1009 	if (scnsir == NULL) {
1010 		/* software intr: calls tty code, hence IPL_TTY */
1011 		scnsir = softint_establish(SOFTINT_SERIAL, scnsoft, NULL);
1012 	}
1013 
1014 	duart_base[DU_ACR] = (duart->mode & ACR_BRG) | duart->acr;
1015 
1016 	if (console)
1017 		speed = scnconsrate;
1018 	else
1019 		speed = scndefaultrate;
1020 
1021 	scn_config(unit, channel, speed, speed, MR1_PNONE | MR1_CS8, MR2_STOP1);
1022 	if (console) {
1023 		maj = cdevsw_lookup_major(&scn_cdevsw);
1024 		KASSERT(maj != NODEVMAJOR);
1025 		shutdownhook_establish(scncnreinit, NULL);
1026 		/* Make sure console can do scncngetc */
1027 		duart_base[DU_OPSET] = channel ? (OP_RTSB | OP_DTRB) :
1028 			(OP_RTSA | OP_DTRA);
1029 	}
1030 
1031 	/* Turn on the receiver and transmitters */
1032 	ch_base[CH_CR] = CR_ENA_RX | CR_ENA_TX;
1033 
1034 	/* Set up the interrupts. */
1035 	duart->imr |= INT_IP;
1036 	scn_rxdisable(sc);
1037 	splx(s);
1038 
1039 	if (sc->sc_swflags) {
1040 		printf("%c flags %d", delim, sc->sc_swflags);
1041 		delim = ',';
1042 	}
1043 
1044 #ifdef KGDB
1045 	major = cdevsw_lookup_major(&scn_cdevsw);
1046 	KASSERT(major != NODEVMAJOR);
1047 	if (kgdb_dev == makedev(major, unit)) {
1048 		if (console)
1049 			kgdb_dev = NODEV; /* can't debug over console port */
1050 		else {
1051 			scninit(kgdb_dev, kgdb_rate);
1052 			scn_rxenable(sc);
1053 			scn->sc_iskgdb = 1;
1054 			kgdb_attach(scncngetc, scncnputc, kgdb_dev);
1055 			if (kgdb_debug_init) {
1056 				printf("%c ", delim);
1057 				kgdb_connect(1);
1058 			} else
1059 				printf("%c kgdb enabled", delim);
1060 			delim = ',';
1061 		}
1062 	}
1063 #endif
1064 	printf("\n");
1065 }
1066 
1067 /* ARGSUSED */
1068 int
1069 scnopen(dev_t dev, int flags, int mode, struct lwp *l)
1070 {
1071 	struct tty *tp;
1072 	int unit = DEV_UNIT(dev);
1073 	struct scn_softc *sc;
1074 	int error = 0;
1075 	int hwset = 0;
1076 
1077 	if (unit >= scn_cd.cd_ndevs)
1078 		return ENXIO;
1079 	sc = SOFTC(unit);
1080 	if (!sc)
1081 		return ENXIO;
1082 
1083 	tp = sc->sc_tty;
1084 	if (!tp) {
1085 		tp = ttymalloc();
1086 		sc->sc_tty = sc->sc_duart->chan[sc->sc_channel].tty = tp;
1087 		tty_attach(tp);
1088 	}
1089 
1090 	tp->t_oproc = scnstart;
1091 	tp->t_param = scnparam;
1092 	tp->t_hwiflow = scnhwiflow;
1093 	tp->t_dev = dev;
1094 
1095 	if (kauth_authorize_device_tty(l->l_cred, KAUTH_DEVICE_TTY_OPEN, tp))
1096 		return (EBUSY);
1097 
1098 	mutex_spin_enter(&tty_lock);
1099 
1100 	if ((tp->t_state & TS_ISOPEN) == 0 && tp->t_wopen == 0) {
1101 		ttychars(tp);
1102 		tp->t_iflag = TTYDEF_IFLAG;
1103 		tp->t_oflag = TTYDEF_OFLAG;
1104 		tp->t_cflag = SCNDEF_CFLAG;
1105 
1106 		sc->sc_rx_blocked = 0;
1107 
1108 		if (sc->sc_swflags & SCN_SW_CLOCAL)
1109 			tp->t_cflag |= CLOCAL;
1110 		if (sc->sc_swflags & SCN_SW_CRTSCTS)
1111 			tp->t_cflag |= CCTS_OFLOW | CRTS_IFLOW;
1112 		tp->t_lflag = TTYDEF_LFLAG;
1113 		if (sc->sc_isconsole)
1114 			tp->t_ispeed = tp->t_ospeed = scnconsrate;
1115 		else
1116 			tp->t_ispeed = tp->t_ospeed = scndefaultrate;
1117 		scnparam(tp, &tp->t_termios);
1118 		ttsetwater(tp);
1119 
1120 		/* Turn on DTR and RTS. */
1121 		SCN_OP_BIS(sc, sc->sc_op_rts | sc->sc_op_dtr);
1122 
1123 		/* enable receiver interrupts */
1124 		scn_rxenable(sc);
1125 		hwset = 1;
1126 
1127 		/* set carrier state; */
1128 		if ((sc->sc_swflags & SCN_SW_SOFTCAR) || /* check ttyflags */
1129 		    SCN_DCD(sc) ||			 /* check h/w */
1130 		    DEV_DIALOUT(dev))
1131 			tp->t_state |= TS_CARR_ON;
1132 		else
1133 			tp->t_state &= ~TS_CARR_ON;
1134 	}
1135 
1136 	mutex_spin_exit(&tty_lock);
1137 
1138 	error = ttyopen(tp, SCN_DIALOUT(sc), flags & O_NONBLOCK);
1139 if (error) printf("ttyopen failed line %d, error %d\n", __LINE__, error);
1140 	if (error)
1141 		goto bad;
1142 
1143 	error = (*tp->t_linesw->l_open) (dev, tp);
1144 if (error) printf("l_open failed line %d, error %d\n", __LINE__, error);
1145 	if (error)
1146 		goto bad;
1147 
1148 	return (0);
1149 
1150 bad:
1151 	if ((tp->t_state & TS_ISOPEN) == 0 && tp->t_wopen == 0) {
1152 		scn_rxdisable(sc);
1153 		SCN_OP_BIC(sc, sc->sc_op_rts | sc->sc_op_dtr);
1154 	}
1155 
1156 	return (error);
1157 }
1158 
1159 
1160 /*ARGSUSED*/
1161 int
1162 scnclose(dev_t dev, int flags, int mode, struct lwp *l)
1163 {
1164 	int unit = DEV_UNIT(dev);
1165 	struct scn_softc *sc = SOFTC(unit);
1166 	struct tty *tp = sc->sc_tty;
1167 	devmajor_t major;
1168 
1169 	(void)major;
1170 
1171 	if ((tp->t_state & TS_ISOPEN) == 0)
1172 		return 0;
1173 
1174 	(*tp->t_linesw->l_close) (tp, flags);
1175 
1176 #ifdef KGDB
1177 	/* do not disable interrupts if debugging */
1178 	major = cdevsw_lookup_major(&scn_devsw);
1179 	KASSERT(major != cdevsw_lookup_major);
1180 	if (kgdb_dev != makedev(major, unit))
1181 #endif
1182 		if ((tp->t_state & TS_ISOPEN) == 0) {
1183 			scn_rxdisable(sc);
1184 		}
1185 	if ((tp->t_cflag & HUPCL) && (sc->sc_swflags & SCN_SW_SOFTCAR) == 0) {
1186 		SCN_OP_BIC(sc, sc->sc_op_dtr);
1187 		/* hold low for 1 second */
1188 		tsleep(sc, TTIPRI, ttclos, hz);
1189 	}
1190 	SCN_CLRDIALOUT(sc);
1191 	ttyclose(tp);
1192 
1193 #if 0
1194 	if ((tp->t_state & TS_ISOPEN) == 0) {
1195 		ttyfree(tp);
1196 		sc->sc_tty = (struct tty *) NULL;
1197 	}
1198 #endif
1199 
1200 	return (0);
1201 }
1202 
1203 int
1204 scnread(dev_t dev, struct uio *uio, int flags)
1205 {
1206 	struct scn_softc *sc = SOFTC(DEV_UNIT(dev));
1207 	struct tty *tp = sc->sc_tty;
1208 
1209 	return ((*tp->t_linesw->l_read) (tp, uio, flags));
1210 }
1211 
1212 int
1213 scnwrite(dev_t dev, struct uio *uio, int flags)
1214 {
1215 	struct scn_softc *sc = SOFTC(DEV_UNIT(dev));
1216 	struct tty *tp = sc->sc_tty;
1217 
1218 	return ((*tp->t_linesw->l_write) (tp, uio, flags));
1219 }
1220 
1221 int
1222 scnpoll(dev_t dev, int events, struct lwp *l)
1223 {
1224 	struct scn_softc *sc = SOFTC(DEV_UNIT(dev));
1225 	struct tty *tp = sc->sc_tty;
1226 
1227 	return ((*tp->t_linesw->l_poll)(tp, events, l));
1228 }
1229 
1230 struct tty *
1231 scntty(dev_t dev)
1232 {
1233 	struct scn_softc *sc = SOFTC(DEV_UNIT(dev));
1234 
1235 	return sc->sc_tty;
1236 }
1237 
1238 /* Worker routines for interrupt processing */
1239 static inline void
1240 dcd_int(struct scn_softc *sc, struct tty *tp, u_char new)
1241 {
1242 
1243 	if (sc->sc_swflags & SCN_SW_SOFTCAR)
1244 		return;
1245 
1246 #if 0
1247 	printf("scn%d: dcd_int ip %x SCN_DCD %x new %x ipcr %x\n",
1248 	    sc->unit,
1249 	    sc->sc_duart->base[DU_IP],
1250 	    SCN_DCD(sc),
1251 	    new,
1252 	    sc->sc_duart->base[DU_IPCR]
1253 	    );
1254 #endif
1255 
1256 /* XXX set some flag to have some lower (soft) int call line discipline? */
1257 	if (!(*tp->t_linesw->l_modem) (tp, new == 0? 1: 0)) {
1258 		SCN_OP_BIC(sc, sc->sc_op_rts | sc->sc_op_dtr);
1259 	}
1260 }
1261 
1262 /*
1263  * Print out a ring or fifo overrun error message.
1264  */
1265 static void
1266 scnoverrun(int unit, long *ptime, const char *what)
1267 {
1268 
1269 	if (*ptime != time_second) {
1270 		*ptime = time_second;
1271 		log(LOG_WARNING, "scn%d: %s overrun\n", unit, what);
1272 	}
1273 }
1274 
1275 /*
1276  * Try to block or unblock input using hardware flow-control.
1277  * This is called by kern/tty.c if MDMBUF|CRTSCTS is set, and
1278  * if this function returns non-zero, the TS_TBLOCK flag will
1279  * be set or cleared according to the "stop" arg passed.
1280  */
1281 int
1282 scnhwiflow(struct tty *tp, int stop)
1283 {
1284 	int unit = DEV_UNIT(tp->t_dev);
1285 	struct scn_softc *sc = SOFTC(unit);
1286 	int s;
1287 
1288 	s = splrtty();
1289 	if (!stop) {
1290 		if (sc->sc_rbput - sc->sc_rbget - 1) {
1291 			setsoftscn();
1292 		}
1293 	}
1294 	splx(s);
1295 	return 1;
1296 }
1297 
1298 static int
1299 scnintr(void *arg)
1300 {
1301 	struct duart *duart = arg;
1302 	struct scn_softc *sc0 = duart->chan[0].sc;
1303 	struct scn_softc *sc1 = duart->chan[1].sc;
1304 
1305 	struct tty *tp0 = (sc0 != NULL) ? sc0->sc_tty : NULL;
1306 	struct tty *tp1 = (sc1 != NULL) ? sc1->sc_tty : NULL;
1307 
1308 	char rs_work;
1309 	u_char rs_stat;
1310 	u_char rs_ipcr;
1311 
1312 	/* Check for RX interrupts first, since we cannot distinguish by irq. */
1313 	scnrxintr(duart);
1314 
1315 	do {
1316 		/* Loop to pick up ALL pending interrupts for device. */
1317 		rs_work = false;
1318 		rs_stat = duart->base[DU_ISR];
1319 
1320 /* channel a */
1321 		if (tp0 != NULL) {
1322 			if ((rs_stat & INT_TXA) && (tp0->t_state & TS_BUSY)) {
1323 				/* output char done. */
1324 				tp0->t_state &= ~(TS_BUSY | TS_FLUSH);
1325 
1326 				/* disable tx ints */
1327 				duart->imr &= ~sc0->sc_tx_int;
1328 				duart->base[DU_IMR] = duart->imr;
1329 
1330 				if (sc0->sc_heldchanges) {
1331 					scn_setchip(sc0);
1332 				}
1333 
1334 				(*tp0->t_linesw->l_start) (tp0);
1335 				rs_work = true;
1336 			}
1337 		}
1338 		/* channel b */
1339 		if (tp1 != NULL) {
1340 			if ((rs_stat & INT_TXB) && (tp1->t_state & TS_BUSY)) {
1341 				/* output char done. */
1342 				tp1->t_state &= ~(TS_BUSY | TS_FLUSH);
1343 
1344 				/* disable tx ints */
1345 				duart->imr &= ~sc1->sc_tx_int;
1346 				duart->base[DU_IMR] = duart->imr;
1347 
1348 				if (sc1->sc_heldchanges) {
1349 					scn_setchip(sc1);
1350 				}
1351 
1352 				(*tp1->t_linesw->l_start) (tp1);
1353 				rs_work = true;
1354 			}
1355 		}
1356 		if (rs_stat & INT_IP) {
1357 			rs_work = true;
1358 			rs_ipcr = duart->base[DU_IPCR];
1359 
1360 			if (rs_ipcr & IPCR_DELTA_DCDA && tp0 != NULL) {
1361 				dcd_int(sc0, tp0, rs_ipcr & IPCR_DCDA);
1362 			}
1363 			if (rs_ipcr & IPCR_DELTA_DCDB && tp1 != NULL) {
1364 				dcd_int(sc1, tp1, rs_ipcr & IPCR_DCDB);
1365 			}
1366 		}
1367 	} while (rs_work);
1368 
1369 	return (1);	/* ? */
1370 }
1371 
1372 /*
1373  * Handle rxrdy/ffull interrupt: QUICKLY poll both channels (checking
1374  * status first) and stash data in a ring buffer.  Ring buffer scheme
1375  * borowed from sparc/zs.c requires NO interlock on data!
1376  *
1377  * This interrupt should NOT be included in spltty() mask since it
1378  * invokes NO tty code!  The whole point is to allow tty input as much
1379  * of the time as possible, while deferring "heavy" character
1380  * processing until later.
1381  *
1382  * see scn.hw.README and scnsoft() for more info.
1383  *
1384  * THIS ROUTINE SHOULD BE KEPT AS CLEAN AS POSSIBLE!!
1385  * IT'S A CANDIDATE FOR RECODING IN ASSEMBLER!!
1386  */
1387 static inline int
1388 scn_rxintr(struct scn_softc *sc)
1389 {
1390 	char sr;
1391 	int i, n;
1392 	int work;
1393 
1394 	work = 0;
1395 	i = sc->sc_rbput;
1396 	while (work <= 10) {
1397 #define SCN_GETCH(SC) \
1398 		sr = (SC)->sc_chbase[CH_SR]; \
1399 		if ((sr & SR_RX_RDY) == 0) \
1400 			break; \
1401 		if (sr & (SR_PARITY | SR_FRAME | SR_BREAK | SR_OVERRUN)) \
1402 			goto exception; \
1403 		work++; \
1404 		(SC)->sc_rbuf[i++ & SCN_RING_MASK] = (SC)->sc_chbase[CH_DAT]
1405 
1406 		SCN_GETCH(sc); SCN_GETCH(sc); SCN_GETCH(sc);
1407 		/* XXX more here if 26C92? -plb */
1408 		continue;
1409 	exception:
1410 #if defined(DDB)
1411 		if (sc->sc_isconsole && (sr & SR_BREAK)) {
1412 			Debugger();
1413 			sr = sc->sc_chbase[CH_SR];
1414 		}
1415 #endif
1416 #if defined(KGDB)
1417 		if (sc->sc_iskgdb && (sr & SR_RX_RDY)) {
1418 			kgdb_connect(1);
1419 			sr = sc->sc_chbase[CH_SR];
1420 		}
1421 #endif
1422 		work++;
1423 		sc->sc_rbuf[i++ & SCN_RING_MASK] = (sr << 8) | sc->sc_chbase[CH_DAT];
1424 		sc->sc_chbase[CH_CR] = CR_CMD_RESET_ERR;	/* resets break? */
1425 		RECOVER();
1426 	}
1427 	/*
1428 	 * If ring is getting too full, try to block input.
1429 	 */
1430 	n = i - sc->sc_rbget;
1431 	if (sc->sc_rbhiwat && (n > sc->sc_rbhiwat)) {
1432 		/* If not CRTSCTS sc_rbhiwat is such that this
1433 		 *  never happens.
1434 		 * Clear RTS
1435 		 */
1436 		SCN_OP_BIC(sc, sc->sc_op_rts);
1437 		sc->sc_rx_blocked = 1;
1438 	}
1439 	sc->sc_rbput = i;
1440 
1441 	return work;
1442 }
1443 
1444 static void
1445 scnrxintr(void *arg)
1446 {
1447 	struct duart *duart = arg;
1448 	int work = 0;
1449 
1450 	if (duart->chan[0].sc != NULL)
1451 		work += scn_rxintr(duart->chan[0].sc);
1452 	if (duart->chan[1].sc != NULL)
1453 		work += scn_rxintr(duart->chan[1].sc);
1454 	if (work > 0) {
1455 		setsoftscn();	/* trigger s/w intr */
1456 #ifdef SCN_TIMING
1457 		microtime(&tstart);
1458 #endif
1459 	}
1460 }
1461 
1462 /*
1463  * Here on soft interrupt (at spltty) to empty ring buffers.
1464  *
1465  * Dave's original scheme was to use the DUART receiver timeout
1466  * interrupt. This requires 2692's (which my board doesn't have), and
1467  * I also liked the idea of using the C/T to generate alternate and/or
1468  * arbitrary bauds. -plb
1469  *
1470  * The ringbuffer code comes from Chris Torek's SPARC 44bsd zs driver
1471  * (hence the LBL notice on top of this file), DOES NOT require
1472  * interlocking with interrupt levels!
1473  *
1474  * The 44bsd sparc/zs driver reads the ring buffer from a separate
1475  * zssoftint, while the SunOS 4.x zs driver appears to use
1476  * timeout()'s.  timeouts seem to be too slow to deal with high data
1477  * rates.  I know, I tried them.
1478  * -plb.
1479  */
1480 static void
1481 scnsoft(void *arg)
1482 {
1483 	int s, unit;
1484 #ifdef SCN_TIMING
1485 	struct timeval tend;
1486 	u_long  t;
1487 
1488 	microtime(&tend);
1489 	t = (tend.tv_sec - tstart.tv_sec) * 1000000 + (tend.tv_usec - tstart.tv_usec);
1490 	t = (t + tick / 20) / (tick / 10);
1491 	if (t >= NJITTER - 1) {
1492 		t = NJITTER - 1;
1493 	}
1494 	scn_jitter[t]++;
1495 #endif
1496 
1497 	for (unit = 0; unit < scn_cd.cd_ndevs; unit++) {
1498 		struct scn_softc *sc;
1499 		struct tty *tp;
1500 		int n, get;
1501 
1502 		sc = SOFTC(unit);
1503 		if (sc == NULL) {
1504 			continue;
1505 		}
1506 		tp = sc->sc_tty;
1507 #ifdef KGDB
1508 		if (tp == NULL) {
1509 			sc->sc_rbget = sc->sc_rbput;
1510 			continue;
1511 		}
1512 #endif
1513 		if (tp == NULL || tp->t_state & TS_TBLOCK) {
1514 			continue;
1515 		}
1516 
1517 
1518 		get = sc->sc_rbget;
1519 
1520 		/* NOTE: fetch from rbput is atomic */
1521 		while (get != (n = sc->sc_rbput)) {
1522 			/*
1523 			 * Compute the number of interrupts in the receive ring.
1524 			 * If the count is overlarge, we lost some events, and
1525 			 * must advance to the first valid one.  It may get
1526 			 * overwritten if more data are arriving, but this is
1527 			 * too expensive to check and gains nothing (we already
1528 			 * lost out; all we can do at this point is trade one
1529 			 * kind of loss for another).
1530 			 */
1531 			n -= get;
1532 			if (n > SCN_RING_SIZE) {
1533 				scnoverrun(unit, &sc->sc_rotime, "ring");
1534 				get += n - SCN_RING_SIZE;
1535 				n = SCN_RING_SIZE;
1536 				sc->sc_ring_overruns++;
1537 			}
1538 			while (--n >= 0) {
1539 				int c, sr;
1540 
1541 				if (tp->t_state & TS_TBLOCK) {
1542 					sc->sc_rbget = get;
1543 					goto done;
1544 				}
1545 				/* Race to keep ahead of incoming interrupts. */
1546 				c = sc->sc_rbuf[get++ & SCN_RING_MASK];
1547 
1548 				sr = c >> 8;	/* extract status */
1549 				c &= 0xff;	/* leave just character */
1550 
1551 				if (sr & SR_OVERRUN) {
1552 					scnoverrun(unit, &sc->sc_fotime, "fifo");
1553 					sc->sc_fifo_overruns++;
1554 				}
1555 				if (sr & SR_PARITY) {
1556 					c |= TTY_PE;
1557 					sc->sc_parity_errors++;
1558 				}
1559 				if (sr & SR_FRAME) {
1560 					c |= TTY_FE;
1561 					sc->sc_framing_errors++;
1562 				}
1563 				if (sr & SR_BREAK) {
1564 #if 0
1565 					/*
1566 					 * See DDB_CHECK() comments in
1567 					 * scnrxintr()
1568 					 */
1569 					if (sc->sc_isconsole)
1570 						Debugger();
1571 #endif
1572 					c = TTY_FE | 0;
1573 					sc->sc_breaks++;
1574 				}
1575 
1576 				(*tp->t_linesw->l_rint) (c, tp);
1577 
1578 				if (sc->sc_rx_blocked && n < SCN_RING_THRESH) {
1579 					s = splrtty();
1580 					sc->sc_rx_blocked = 0;
1581 					SCN_OP_BIS(sc, sc->sc_op_rts);
1582 					splx(s);
1583 				}
1584 
1585 			}
1586 			sc->sc_rbget = get;
1587 		}
1588 	done: ;
1589 	}
1590 }
1591 
1592 /* Convert TIOCM_xxx bits to output port bits. */
1593 static unsigned char
1594 opbits(struct scn_softc *sc, int tioc_bits)
1595 {
1596 
1597 	return ((((tioc_bits) & TIOCM_DTR) ? sc->sc_op_dtr : 0) |
1598 	    (((tioc_bits) & TIOCM_RTS) ? sc->sc_op_rts : 0));
1599 }
1600 
1601 int
1602 scnioctl(dev_t dev, u_long cmd, void *data, int flags, struct lwp *l)
1603 {
1604 	int unit = DEV_UNIT(dev);
1605 	struct scn_softc *sc = SOFTC(unit);
1606 	struct tty *tp = sc->sc_tty;
1607 	int error;
1608 
1609 	error = (*tp->t_linesw->l_ioctl) (tp, cmd, data, flags, l);
1610 	if (error != EPASSTHROUGH)
1611 		return (error);
1612 
1613 	error = ttioctl(tp, cmd, data, flags, l);
1614 	if (error != EPASSTHROUGH)
1615 		return (error);
1616 
1617 	switch (cmd) {
1618 	case TIOCSBRK:
1619 		sc->sc_chbase[CH_CR] = CR_CMD_START_BRK;
1620 		break;
1621 
1622 	case TIOCCBRK:
1623 		sc->sc_chbase[CH_CR] = CR_CMD_STOP_BRK;
1624 		break;
1625 
1626 	case TIOCSDTR:
1627 		SCN_OP_BIS(sc, sc->sc_op_dtr | sc->sc_op_rts);
1628 		break;
1629 
1630 	case TIOCCDTR:
1631 		SCN_OP_BIC(sc, sc->sc_op_dtr | sc->sc_op_rts);
1632 		break;
1633 
1634 	case TIOCMSET: {
1635 			int     s;
1636 			unsigned char sbits, cbits;
1637 
1638 			/* set bits */
1639 			sbits = opbits(sc, *(int *) data);
1640 
1641 			/* get bits to clear */
1642 			cbits = ~sbits & (sc->sc_op_dtr | sc->sc_op_rts);
1643 
1644 			s = spltty();
1645 			if (sbits) {
1646 				SCN_OP_BIS(sc, sbits);
1647 			}
1648 			if (cbits) {
1649 				SCN_OP_BIC(sc, cbits);
1650 			}
1651 			splx(s);
1652 			break;
1653 		}
1654 
1655 	case TIOCMBIS:
1656 		SCN_OP_BIS(sc, opbits(sc, *(int *) data));
1657 		break;
1658 
1659 	case TIOCMBIC:
1660 		SCN_OP_BIC(sc, opbits(sc, *(int *) data));
1661 		break;
1662 
1663 	case TIOCMGET: {
1664 			int     bits;
1665 			unsigned char ip, op;
1666 
1667 			/* s = spltty(); */
1668 			ip = sc->sc_duart->base[DU_IP];
1669 			/*
1670 			 * XXX sigh; cannot get op current state!! even if
1671 			 * maintained in private, RTS is done in h/w!!
1672 			 */
1673 			op = 0;
1674 			/* splx(s); */
1675 
1676 			bits = 0;
1677 			if (ip & sc->sc_ip_dcd)
1678 				bits |= TIOCM_CD;
1679 			if (ip & sc->sc_ip_cts)
1680 				bits |= TIOCM_CTS;
1681 
1682 #if 0
1683 			if (op & sc->sc_op_dtr)
1684 				bits |= TIOCM_DTR;
1685 			if (op & sc->sc_op_rts)
1686 				bits |= TIOCM_RTS;
1687 #endif
1688 
1689 			*(int *) data = bits;
1690 			break;
1691 		}
1692 
1693 	case TIOCGFLAGS:{
1694 			int     bits = 0;
1695 
1696 			if (sc->sc_swflags & SCN_SW_SOFTCAR)
1697 				bits |= TIOCFLAG_SOFTCAR;
1698 			if (sc->sc_swflags & SCN_SW_CLOCAL)
1699 				bits |= TIOCFLAG_CLOCAL;
1700 			if (sc->sc_swflags & SCN_SW_CRTSCTS)
1701 				bits |= TIOCFLAG_CRTSCTS;
1702 			if (sc->sc_swflags & SCN_SW_MDMBUF)
1703 				bits |= TIOCFLAG_MDMBUF;
1704 
1705 			*(int *) data = bits;
1706 			break;
1707 		}
1708 	case TIOCSFLAGS:{
1709 			int     userbits, driverbits = 0;
1710 
1711 			error = kauth_authorize_device_tty(l->l_cred,
1712 			    KAUTH_DEVICE_TTY_PRIVSET, tp);
1713 			if (error != 0)
1714 				return (EPERM);
1715 
1716 			userbits = *(int *) data;
1717 			if (userbits & TIOCFLAG_SOFTCAR)
1718 				driverbits |= SCN_SW_SOFTCAR;
1719 			if (userbits & TIOCFLAG_CLOCAL)
1720 				driverbits |= SCN_SW_CLOCAL;
1721 			if (userbits & TIOCFLAG_CRTSCTS)
1722 				driverbits |= SCN_SW_CRTSCTS;
1723 			if (userbits & TIOCFLAG_MDMBUF)
1724 				driverbits |= SCN_SW_MDMBUF;
1725 
1726 			sc->sc_swflags = driverbits;
1727 
1728 			break;
1729 		}
1730 
1731 	default:
1732 		return (EPASSTHROUGH);
1733 	}
1734 	return (0);
1735 }
1736 
1737 int
1738 scnparam(struct tty *tp, struct termios *t)
1739 {
1740 	int cflag = t->c_cflag;
1741 	int unit = DEV_UNIT(tp->t_dev);
1742 	char mr1, mr2;
1743 	int error;
1744 	struct scn_softc *sc = SOFTC(unit);
1745 
1746 	/* Is this a hang up? */
1747 	if (t->c_ospeed == B0) {
1748 		SCN_OP_BIC(sc, sc->sc_op_dtr);
1749 		/* leave DTR down. see comment in scnclose() -plb */
1750 		return (0);
1751 	}
1752 	mr1 = mr2 = 0;
1753 
1754 	/* Parity? */
1755 	if (cflag & PARENB) {
1756 		if ((cflag & PARODD) == 0)
1757 			mr1 |= MR1_PEVEN;
1758 		else
1759 			mr1 |= MR1_PODD;
1760 	} else
1761 		mr1 |= MR1_PNONE;
1762 
1763 	/* Stop bits. */
1764 	if (cflag & CSTOPB)
1765 		mr2 |= MR2_STOP2;
1766 	else
1767 		mr2 |= MR2_STOP1;
1768 
1769 	/* Data bits. */
1770 	switch (cflag & CSIZE) {
1771 	case CS5:
1772 		mr1 |= MR1_CS5;
1773 		break;
1774 	case CS6:
1775 		mr1 |= MR1_CS6;
1776 		break;
1777 	case CS7:
1778 		mr1 |= MR1_CS7;
1779 		break;
1780 	case CS8:
1781 	default:
1782 		mr1 |= MR1_CS8;
1783 		break;
1784 	}
1785 
1786 	if (cflag & CCTS_OFLOW)
1787 		mr2 |= MR2_TXCTS;
1788 
1789 	if (cflag & CRTS_IFLOW) {
1790 		mr1 |= MR1_RXRTS;
1791 		sc->sc_rbhiwat = SCN_RING_HIWAT;
1792 	} else {
1793 		sc->sc_rbhiwat = 0;
1794 	}
1795 
1796 	error = scn_config(unit, sc->sc_channel, t->c_ispeed,
1797 	    t->c_ospeed, mr1, mr2);
1798 
1799 	/* If successful, copy to tty */
1800 	if (!error) {
1801 		tp->t_ispeed = t->c_ispeed;
1802 		tp->t_ospeed = t->c_ospeed;
1803 		tp->t_cflag = cflag;
1804 	}
1805 	return (error);
1806 }
1807 
1808 /*
1809  * Start or restart a transmission.
1810  */
1811 void
1812 scnstart(struct tty *tp)
1813 {
1814 	int s, c;
1815 	int unit = DEV_UNIT(tp->t_dev);
1816 	struct scn_softc *sc = SOFTC(unit);
1817 
1818 	s = spltty();
1819 	if (tp->t_state & (TS_BUSY | TS_TIMEOUT | TS_TTSTOP))
1820 		goto out;
1821 	if (!ttypull(tp))
1822 		goto out;
1823 
1824 	tp->t_state |= TS_BUSY;
1825 
1826 	while (sc->sc_chbase[CH_SR] & SR_TX_RDY) {
1827 		if ((c = getc(&tp->t_outq)) == -1)
1828 			break;
1829 		sc->sc_chbase[CH_DAT] = c;
1830 	}
1831 	sc->sc_duart->imr |= (sc->sc_tx_int | sc->sc_rx_int);
1832 	sc->sc_duart->base[DU_IMR] = sc->sc_duart->imr;
1833 
1834 out:
1835 	splx(s);
1836 }
1837 
1838 /*
1839  * Stop output on a line.
1840  */
1841 /*ARGSUSED*/
1842 void
1843 scnstop(struct tty *tp, int flags)
1844 {
1845 	int s;
1846 
1847 	s = spltty();
1848 	if (tp->t_state & TS_BUSY) {
1849 		if ((tp->t_state & TS_TTSTOP) == 0)
1850 			tp->t_state |= TS_FLUSH;
1851 	}
1852 	splx(s);
1853 }
1854 
1855 /*
1856  * Following are all routines needed for SCN to act as console.
1857  */
1858 
1859 void
1860 scncnprobe(struct consdev *cn)
1861 {
1862 }
1863 
1864 void
1865 scncnreinit(void *v)
1866 {
1867 	volatile u_char *du_base =
1868 	    (volatile u_char *)MIPS_PHYS_TO_KSEG1(0x1fb80004);
1869 
1870 	du_base[DU_OPSET] =
1871 	    SCN_CONSCHAN ? (OP_RTSB | OP_DTRB) : (OP_RTSA | OP_DTRA);
1872 }
1873 
1874 void
1875 scncninit(struct consdev *cn)
1876 {
1877 	devmajor_t major;
1878 
1879 	/* initialize required fields */
1880 	major = cdevsw_lookup_major(&scn_cdevsw);
1881 	KASSERT(major != NODEV);
1882 	cn->cn_dev = makedev(major, SCN_CONSOLE);
1883 	cn->cn_pri = CN_REMOTE;
1884 
1885 	scninit(cn->cn_dev, scnconsrate);
1886 }
1887 
1888 /* Used by scncninit and kgdb startup. */
1889 int
1890 scninit(dev_t dev, int rate)
1891 {
1892 /* XXX - maintain PROM's settings */
1893 #if 0
1894 	volatile u_char *du_base =
1895 	    (volatile u_char *)MIPS_PHYS_TO_KSEG1(0x1fb80004);
1896 	int unit = DEV_UNIT(dev);
1897 
1898 	du_base[DU_OPSET] =
1899 	    SCN_CONSCHAN ? (OP_RTSB | OP_DTRB) : (OP_RTSA | OP_DTRA);
1900 	scn_config(unit, SCN_CONSCHAN, rate, rate,
1901 	    MR1_PNONE | MR1_CS8, MR2_STOP1);
1902 #endif
1903 	return (0);
1904 }
1905 
1906 /*
1907  * Console kernel input character routine.
1908  */
1909 int
1910 scncngetc(dev_t dev)
1911 {
1912 	volatile u_char *ch_base =
1913 	    (volatile u_char *)MIPS_PHYS_TO_KSEG1(0x1fb80004);
1914 	char c;
1915 	int s;
1916 
1917 	s = spltty();
1918 
1919 	while ((ch_base[CH_SR] & SR_RX_RDY) == 0)
1920 		;
1921 	c = ch_base[CH_DAT];
1922 
1923 	splx(s);
1924 	return c;
1925 }
1926 
1927 void
1928 scncnpollc(dev_t dev, int on)
1929 {
1930 }
1931 
1932 /*
1933  * Console kernel output character routine.
1934  */
1935 void
1936 scncnputc(dev_t dev, int c)
1937 {
1938 	volatile u_char *ch_base =
1939 	    (volatile u_char *)MIPS_PHYS_TO_KSEG1(0x1fb80004);
1940 	volatile u_char *du_base =
1941 	    (volatile u_char *)MIPS_PHYS_TO_KSEG1(0x1fb80004);
1942 	int s;
1943 
1944 	s = spltty();
1945 
1946 	if (c == '\n')
1947 		scncnputc(dev, '\r');
1948 
1949 	while ((ch_base[CH_SR] & SR_TX_RDY) == 0)
1950 		;
1951 	ch_base[CH_DAT] = c;
1952 	while ((ch_base[CH_SR] & SR_TX_RDY) == 0)
1953 		;
1954 	du_base[DU_ISR];
1955 
1956 	splx(s);
1957 }
1958