xref: /netbsd-src/sys/dev/ic/z8530tty.c (revision e5548b402ae4c44fb816de42c7bba9581ce23ef5)
1 /*	$NetBSD: z8530tty.c,v 1.101 2005/12/11 12:21:29 christos Exp $	*/
2 
3 /*-
4  * Copyright (c) 1993, 1994, 1995, 1996, 1997, 1998, 1999
5  *	Charles M. Hannum.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. All advertising materials mentioning features or use of this software
16  *    must display the following acknowledgement:
17  *	This product includes software developed by Charles M. Hannum.
18  * 4. The name of the author may not be used to endorse or promote products
19  *    derived from this software without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
23  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
24  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
25  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
26  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
30  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31  */
32 
33 /*
34  * Copyright (c) 1992, 1993
35  *	The Regents of the University of California.  All rights reserved.
36  *
37  * This software was developed by the Computer Systems Engineering group
38  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
39  * contributed to Berkeley.
40  *
41  * All advertising materials mentioning features or use of this software
42  * must display the following acknowledgement:
43  *	This product includes software developed by the University of
44  *	California, Lawrence Berkeley Laboratory.
45  *
46  * Redistribution and use in source and binary forms, with or without
47  * modification, are permitted provided that the following conditions
48  * are met:
49  * 1. Redistributions of source code must retain the above copyright
50  *    notice, this list of conditions and the following disclaimer.
51  * 2. Redistributions in binary form must reproduce the above copyright
52  *    notice, this list of conditions and the following disclaimer in the
53  *    documentation and/or other materials provided with the distribution.
54  * 3. Neither the name of the University nor the names of its contributors
55  *    may be used to endorse or promote products derived from this software
56  *    without specific prior written permission.
57  *
58  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
59  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
60  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
61  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
62  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
63  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
64  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
65  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
66  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
67  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
68  * SUCH DAMAGE.
69  *
70  *	@(#)zs.c	8.1 (Berkeley) 7/19/93
71  */
72 
73 /*
74  * Copyright (c) 1994 Gordon W. Ross
75  *
76  * This software was developed by the Computer Systems Engineering group
77  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
78  * contributed to Berkeley.
79  *
80  * All advertising materials mentioning features or use of this software
81  * must display the following acknowledgement:
82  *	This product includes software developed by the University of
83  *	California, Lawrence Berkeley Laboratory.
84  *
85  * Redistribution and use in source and binary forms, with or without
86  * modification, are permitted provided that the following conditions
87  * are met:
88  * 1. Redistributions of source code must retain the above copyright
89  *    notice, this list of conditions and the following disclaimer.
90  * 2. Redistributions in binary form must reproduce the above copyright
91  *    notice, this list of conditions and the following disclaimer in the
92  *    documentation and/or other materials provided with the distribution.
93  * 3. All advertising materials mentioning features or use of this software
94  *    must display the following acknowledgement:
95  *	This product includes software developed by the University of
96  *	California, Berkeley and its contributors.
97  * 4. Neither the name of the University nor the names of its contributors
98  *    may be used to endorse or promote products derived from this software
99  *    without specific prior written permission.
100  *
101  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
102  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
103  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
104  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
105  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
106  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
107  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
108  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
109  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
110  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
111  * SUCH DAMAGE.
112  *
113  *	@(#)zs.c	8.1 (Berkeley) 7/19/93
114  */
115 
116 /*
117  * Zilog Z8530 Dual UART driver (tty interface)
118  *
119  * This is the "slave" driver that will be attached to
120  * the "zsc" driver for plain "tty" async. serial lines.
121  *
122  * Credits, history:
123  *
124  * The original version of this code was the sparc/dev/zs.c driver
125  * as distributed with the Berkeley 4.4 Lite release.  Since then,
126  * Gordon Ross reorganized the code into the current parent/child
127  * driver scheme, separating the Sun keyboard and mouse support
128  * into independent child drivers.
129  *
130  * RTS/CTS flow-control support was a collaboration of:
131  *	Gordon Ross <gwr@NetBSD.org>,
132  *	Bill Studenmund <wrstuden@loki.stanford.edu>
133  *	Ian Dall <Ian.Dall@dsto.defence.gov.au>
134  *
135  * The driver was massively overhauled in November 1997 by Charles Hannum,
136  * fixing *many* bugs, and substantially improving performance.
137  */
138 
139 #include <sys/cdefs.h>
140 __KERNEL_RCSID(0, "$NetBSD: z8530tty.c,v 1.101 2005/12/11 12:21:29 christos Exp $");
141 
142 #include "opt_kgdb.h"
143 #include "opt_ntp.h"
144 
145 #include <sys/param.h>
146 #include <sys/systm.h>
147 #include <sys/proc.h>
148 #include <sys/device.h>
149 #include <sys/conf.h>
150 #include <sys/file.h>
151 #include <sys/ioctl.h>
152 #include <sys/malloc.h>
153 #include <sys/timepps.h>
154 #include <sys/tty.h>
155 #include <sys/time.h>
156 #include <sys/kernel.h>
157 #include <sys/syslog.h>
158 
159 #include <dev/ic/z8530reg.h>
160 #include <machine/z8530var.h>
161 
162 #include <dev/cons.h>
163 
164 #include "locators.h"
165 
166 /*
167  * How many input characters we can buffer.
168  * The port-specific var.h may override this.
169  * Note: must be a power of two!
170  */
171 #ifndef	ZSTTY_RING_SIZE
172 #define	ZSTTY_RING_SIZE	2048
173 #endif
174 
175 static struct cnm_state zstty_cnm_state;
176 /*
177  * Make this an option variable one can patch.
178  * But be warned:  this must be a power of 2!
179  */
180 u_int zstty_rbuf_size = ZSTTY_RING_SIZE;
181 
182 /* Stop input when 3/4 of the ring is full; restart when only 1/4 is full. */
183 u_int zstty_rbuf_hiwat = (ZSTTY_RING_SIZE * 1) / 4;
184 u_int zstty_rbuf_lowat = (ZSTTY_RING_SIZE * 3) / 4;
185 
186 static int zsppscap =
187 	PPS_TSFMT_TSPEC |
188 	PPS_CAPTUREASSERT |
189 	PPS_CAPTURECLEAR |
190 	PPS_OFFSETASSERT | PPS_OFFSETCLEAR;
191 
192 struct zstty_softc {
193 	struct	device zst_dev;		/* required first: base device */
194 	struct  tty *zst_tty;
195 	struct	zs_chanstate *zst_cs;
196 
197 	struct callout zst_diag_ch;
198 
199 	u_int zst_overflows,
200 	      zst_floods,
201 	      zst_errors;
202 
203 	int zst_hwflags,	/* see z8530var.h */
204 	    zst_swflags;	/* TIOCFLAG_SOFTCAR, ... <ttycom.h> */
205 
206 	u_int zst_r_hiwat,
207 	      zst_r_lowat;
208 	u_char *volatile zst_rbget,
209 	       *volatile zst_rbput;
210 	volatile u_int zst_rbavail;
211 	u_char *zst_rbuf,
212 	       *zst_ebuf;
213 
214 	/*
215 	 * The transmit byte count and address are used for pseudo-DMA
216 	 * output in the hardware interrupt code.  PDMA can be suspended
217 	 * to get pending changes done; heldtbc is used for this.  It can
218 	 * also be stopped for ^S; this sets TS_TTSTOP in tp->t_state.
219 	 */
220 	u_char *zst_tba;		/* transmit buffer address */
221 	u_int zst_tbc,			/* transmit byte count */
222 	      zst_heldtbc;		/* held tbc while xmission stopped */
223 
224 	/* Flags to communicate with zstty_softint() */
225 	volatile u_char zst_rx_flags,	/* receiver blocked */
226 #define	RX_TTY_BLOCKED		0x01
227 #define	RX_TTY_OVERFLOWED	0x02
228 #define	RX_IBUF_BLOCKED		0x04
229 #define	RX_IBUF_OVERFLOWED	0x08
230 #define	RX_ANY_BLOCK		0x0f
231 			zst_tx_busy,	/* working on an output chunk */
232 			zst_tx_done,	/* done with one output chunk */
233 			zst_tx_stopped,	/* H/W level stop (lost CTS) */
234 			zst_st_check,	/* got a status interrupt */
235 			zst_rx_ready;
236 
237 	/* PPS signal on DCD, with or without inkernel clock disciplining */
238 	u_char  zst_ppsmask;			/* pps signal mask */
239 	u_char  zst_ppsassert;			/* pps leading edge */
240 	u_char  zst_ppsclear;			/* pps trailing edge */
241 	pps_info_t ppsinfo;
242 	pps_params_t ppsparam;
243 };
244 
245 /* Macros to clear/set/test flags. */
246 #define SET(t, f)	(t) |= (f)
247 #define CLR(t, f)	(t) &= ~(f)
248 #define ISSET(t, f)	((t) & (f))
249 
250 /* Definition of the driver for autoconfig. */
251 static int	zstty_match(struct device *, struct cfdata *, void *);
252 static void	zstty_attach(struct device *, struct device *, void *);
253 
254 CFATTACH_DECL(zstty, sizeof(struct zstty_softc),
255     zstty_match, zstty_attach, NULL, NULL);
256 
257 extern struct cfdriver zstty_cd;
258 
259 dev_type_open(zsopen);
260 dev_type_close(zsclose);
261 dev_type_read(zsread);
262 dev_type_write(zswrite);
263 dev_type_ioctl(zsioctl);
264 dev_type_stop(zsstop);
265 dev_type_tty(zstty);
266 dev_type_poll(zspoll);
267 
268 const struct cdevsw zstty_cdevsw = {
269 	zsopen, zsclose, zsread, zswrite, zsioctl,
270 	zsstop, zstty, zspoll, nommap, ttykqfilter, D_TTY
271 };
272 
273 struct zsops zsops_tty;
274 
275 static void zs_shutdown(struct zstty_softc *);
276 static void	zsstart(struct tty *);
277 static int	zsparam(struct tty *, struct termios *);
278 static void zs_modem(struct zstty_softc *, int);
279 static void tiocm_to_zs(struct zstty_softc *, u_long, int);
280 static int  zs_to_tiocm(struct zstty_softc *);
281 static int    zshwiflow(struct tty *, int);
282 static void  zs_hwiflow(struct zstty_softc *);
283 static void zs_maskintr(struct zstty_softc *);
284 
285 /* Low-level routines. */
286 static void zstty_rxint  (struct zs_chanstate *);
287 static void zstty_stint  (struct zs_chanstate *, int);
288 static void zstty_txint  (struct zs_chanstate *);
289 static void zstty_softint(struct zs_chanstate *);
290 
291 #define	ZSUNIT(x)	(minor(x) & 0x7ffff)
292 #define	ZSDIALOUT(x)	(minor(x) & 0x80000)
293 
294 struct tty *zstty_get_tty_from_dev(struct device *);
295 
296 /*
297  * XXX get the (struct tty *) out of a (struct device *) we trust to be a
298  * (struct zstty_softc *) - needed by sparc/dev/zs.c, sparc64/dev/zs.c,
299  * sun3/dev/zs.c and sun2/dev/zs.c will probably need it at some point
300  */
301 
302 struct tty *
303 zstty_get_tty_from_dev(struct device *dev)
304 {
305 	struct zstty_softc *sc = (struct zstty_softc *)dev;
306 
307 	return sc->zst_tty;
308 }
309 
310 /*
311  * zstty_match: how is this zs channel configured?
312  */
313 int
314 zstty_match(parent, cf, aux)
315 	struct device *parent;
316 	struct cfdata *cf;
317 	void   *aux;
318 {
319 	struct zsc_attach_args *args = aux;
320 
321 	/* Exact match is better than wildcard. */
322 	if (cf->zsccf_channel == args->channel)
323 		return 2;
324 
325 	/* This driver accepts wildcard. */
326 	if (cf->zsccf_channel == ZSCCF_CHANNEL_DEFAULT)
327 		return 1;
328 
329 	return 0;
330 }
331 
332 void
333 zstty_attach(parent, self, aux)
334 	struct device *parent, *self;
335 	void   *aux;
336 
337 {
338 	struct zsc_softc *zsc = (void *) parent;
339 	struct zstty_softc *zst = (void *) self;
340 	struct cfdata *cf = self->dv_cfdata;
341 	struct zsc_attach_args *args = aux;
342 	struct zs_chanstate *cs;
343 	struct tty *tp;
344 	int channel, s, tty_unit;
345 	dev_t dev;
346 	const char *i, *o;
347 	int dtr_on;
348 	int resetbit;
349 
350 	callout_init(&zst->zst_diag_ch);
351 	cn_init_magic(&zstty_cnm_state);
352 
353 	tty_unit = zst->zst_dev.dv_unit;
354 	channel = args->channel;
355 	cs = zsc->zsc_cs[channel];
356 	cs->cs_private = zst;
357 	cs->cs_ops = &zsops_tty;
358 
359 	zst->zst_cs = cs;
360 	zst->zst_swflags = cf->cf_flags;	/* softcar, etc. */
361 	zst->zst_hwflags = args->hwflags;
362 	dev = makedev(cdevsw_lookup_major(&zstty_cdevsw), tty_unit);
363 
364 	if (zst->zst_swflags)
365 		printf(" flags 0x%x", zst->zst_swflags);
366 
367 	/*
368 	 * Check whether we serve as a console device.
369 	 * XXX - split console input/output channels aren't
370 	 *	 supported yet on /dev/console
371 	 */
372 	i = o = NULL;
373 	if ((zst->zst_hwflags & ZS_HWFLAG_CONSOLE_INPUT) != 0) {
374 		i = "input";
375 		if ((args->hwflags & ZS_HWFLAG_USE_CONSDEV) != 0) {
376 			args->consdev->cn_dev = dev;
377 			cn_tab->cn_pollc = args->consdev->cn_pollc;
378 			cn_tab->cn_getc = args->consdev->cn_getc;
379 		}
380 		cn_tab->cn_dev = dev;
381 		/* Set console magic to BREAK */
382 		cn_set_magic("\047\001");
383 	}
384 	if ((zst->zst_hwflags & ZS_HWFLAG_CONSOLE_OUTPUT) != 0) {
385 		o = "output";
386 		if ((args->hwflags & ZS_HWFLAG_USE_CONSDEV) != 0) {
387 			cn_tab->cn_putc = args->consdev->cn_putc;
388 		}
389 		cn_tab->cn_dev = dev;
390 	}
391 	if (i != NULL || o != NULL)
392 		printf(" (console %s)", i ? (o ? "i/o" : i) : o);
393 
394 #ifdef KGDB
395 	if (zs_check_kgdb(cs, dev)) {
396 		/*
397 		 * Allow kgdb to "take over" this port.  Returns true
398 		 * if this serial port is in-use by kgdb.
399 		 */
400 		printf(" (kgdb)\n");
401 		/*
402 		 * This is the kgdb port (exclusive use)
403 		 * so skip the normal attach code.
404 		 */
405 		return;
406 	}
407 #endif
408 	printf("\n");
409 
410 	tp = ttymalloc();
411 	tp->t_dev = dev;
412 	tp->t_oproc = zsstart;
413 	tp->t_param = zsparam;
414 	tp->t_hwiflow = zshwiflow;
415 	tty_attach(tp);
416 
417 	zst->zst_tty = tp;
418 	zst->zst_rbuf = malloc(zstty_rbuf_size << 1, M_DEVBUF, M_WAITOK);
419 	zst->zst_ebuf = zst->zst_rbuf + (zstty_rbuf_size << 1);
420 	/* Disable the high water mark. */
421 	zst->zst_r_hiwat = 0;
422 	zst->zst_r_lowat = 0;
423 	zst->zst_rbget = zst->zst_rbput = zst->zst_rbuf;
424 	zst->zst_rbavail = zstty_rbuf_size;
425 
426 	/* if there are no enable/disable functions, assume the device
427 	   is always enabled */
428 	if (!cs->enable)
429 		cs->enabled = 1;
430 
431 	/*
432 	 * Hardware init
433 	 */
434 	dtr_on = 0;
435 	resetbit = 0;
436 	if (ISSET(zst->zst_hwflags, ZS_HWFLAG_CONSOLE)) {
437 		/* Call zsparam similar to open. */
438 		struct termios t;
439 
440 		/* Wait a while for previous console output to complete */
441 		DELAY(10000);
442 
443 		/* Setup the "new" parameters in t. */
444 		t.c_ispeed = 0;
445 		t.c_ospeed = cs->cs_defspeed;
446 		t.c_cflag = cs->cs_defcflag;
447 
448 		/*
449 		 * Turn on receiver and status interrupts.
450 		 * We defer the actual write of the register to zsparam(),
451 		 * but we must make sure status interrupts are turned on by
452 		 * the time zsparam() reads the initial rr0 state.
453 		 */
454 		SET(cs->cs_preg[1], ZSWR1_RIE | ZSWR1_SIE);
455 
456 		/* Make sure zsparam will see changes. */
457 		tp->t_ospeed = 0;
458 		(void) zsparam(tp, &t);
459 
460 		/* Make sure DTR is on now. */
461 		dtr_on = 1;
462 
463 	} else if (!ISSET(zst->zst_hwflags, ZS_HWFLAG_NORESET)) {
464 		/* Not the console; may need reset. */
465 		resetbit = (channel == 0) ? ZSWR9_A_RESET : ZSWR9_B_RESET;
466 	}
467 
468 	s = splzs();
469 	simple_lock(&cs->cs_lock);
470 	if (resetbit)
471 		zs_write_reg(cs, 9, resetbit);
472 	zs_modem(zst, dtr_on);
473 	simple_unlock(&cs->cs_lock);
474 	splx(s);
475 }
476 
477 
478 /*
479  * Return pointer to our tty.
480  */
481 struct tty *
482 zstty(dev)
483 	dev_t dev;
484 {
485 	struct zstty_softc *zst = device_lookup(&zstty_cd, ZSUNIT(dev));
486 
487 	return (zst->zst_tty);
488 }
489 
490 
491 void
492 zs_shutdown(zst)
493 	struct zstty_softc *zst;
494 {
495 	struct zs_chanstate *cs = zst->zst_cs;
496 	struct tty *tp = zst->zst_tty;
497 	int s;
498 
499 	s = splzs();
500 	simple_lock(&cs->cs_lock);
501 
502 	/* If we were asserting flow control, then deassert it. */
503 	SET(zst->zst_rx_flags, RX_IBUF_BLOCKED);
504 	zs_hwiflow(zst);
505 
506 	/* Clear any break condition set with TIOCSBRK. */
507 	zs_break(cs, 0);
508 
509 	/* Turn off PPS capture on last close. */
510 	zst->zst_ppsmask = 0;
511 	zst->ppsparam.mode = 0;
512 
513 	/*
514 	 * Hang up if necessary.  Wait a bit, so the other side has time to
515 	 * notice even if we immediately open the port again.
516 	 */
517 	if (ISSET(tp->t_cflag, HUPCL)) {
518 		zs_modem(zst, 0);
519 		simple_unlock(&cs->cs_lock);
520 		splx(s);
521 		/*
522 		 * XXX -    another process is not prevented from opening
523 		 *	    the device during our sleep.
524 		 */
525 		(void) tsleep(cs, TTIPRI, ttclos, hz);
526 		/* Re-check state in case we were opened during our sleep */
527 		if (ISSET(tp->t_state, TS_ISOPEN) || tp->t_wopen != 0)
528 			return;
529 
530 		s = splzs();
531 		simple_lock(&cs->cs_lock);
532 	}
533 
534 	/* Turn off interrupts if not the console. */
535 	if (!ISSET(zst->zst_hwflags, ZS_HWFLAG_CONSOLE)) {
536 		CLR(cs->cs_preg[1], ZSWR1_RIE | ZSWR1_SIE);
537 		cs->cs_creg[1] = cs->cs_preg[1];
538 		zs_write_reg(cs, 1, cs->cs_creg[1]);
539 	}
540 
541 	/* Call the power management hook. */
542 	if (cs->disable) {
543 #ifdef DIAGNOSTIC
544 		if (!cs->enabled)
545 			panic("zs_shutdown: not enabled?");
546 #endif
547 		(*cs->disable)(zst->zst_cs);
548 	}
549 
550 	simple_unlock(&cs->cs_lock);
551 	splx(s);
552 }
553 
554 /*
555  * Open a zs serial (tty) port.
556  */
557 int
558 zsopen(dev, flags, mode, l)
559 	dev_t dev;
560 	int flags;
561 	int mode;
562 	struct lwp *l;
563 {
564 	struct zstty_softc *zst;
565 	struct zs_chanstate *cs;
566 	struct tty *tp;
567 	struct proc *p;
568 	int s, s2;
569 	int error;
570 
571 	zst = device_lookup(&zstty_cd, ZSUNIT(dev));
572 	if (zst == NULL)
573 		return (ENXIO);
574 
575 	tp = zst->zst_tty;
576 	cs = zst->zst_cs;
577 	p = l->l_proc;
578 
579 	/* If KGDB took the line, then tp==NULL */
580 	if (tp == NULL)
581 		return (EBUSY);
582 
583 	if (ISSET(tp->t_state, TS_ISOPEN) &&
584 	    ISSET(tp->t_state, TS_XCLUDE) &&
585 	    suser(p->p_ucred, &p->p_acflag) != 0)
586 		return (EBUSY);
587 
588 	s = spltty();
589 
590 	/*
591 	 * Do the following iff this is a first open.
592 	 */
593 	if (!ISSET(tp->t_state, TS_ISOPEN) && tp->t_wopen == 0) {
594 		struct termios t;
595 
596 		tp->t_dev = dev;
597 
598 		/* Call the power management hook. */
599 		if (cs->enable) {
600 			if ((*cs->enable)(cs)) {
601 				splx(s);
602 				printf("%s: device enable failed\n",
603 			       	zst->zst_dev.dv_xname);
604 				return (EIO);
605 			}
606 		}
607 
608 		/*
609 		 * Initialize the termios status to the defaults.  Add in the
610 		 * sticky bits from TIOCSFLAGS.
611 		 */
612 		t.c_ispeed = 0;
613 		t.c_ospeed = cs->cs_defspeed;
614 		t.c_cflag = cs->cs_defcflag;
615 		if (ISSET(zst->zst_swflags, TIOCFLAG_CLOCAL))
616 			SET(t.c_cflag, CLOCAL);
617 		if (ISSET(zst->zst_swflags, TIOCFLAG_CRTSCTS))
618 			SET(t.c_cflag, CRTSCTS);
619 		if (ISSET(zst->zst_swflags, TIOCFLAG_CDTRCTS))
620 			SET(t.c_cflag, CDTRCTS);
621 		if (ISSET(zst->zst_swflags, TIOCFLAG_MDMBUF))
622 			SET(t.c_cflag, MDMBUF);
623 
624 		s2 = splzs();
625 		simple_lock(&cs->cs_lock);
626 
627 		/*
628 		 * Turn on receiver and status interrupts.
629 		 * We defer the actual write of the register to zsparam(),
630 		 * but we must make sure status interrupts are turned on by
631 		 * the time zsparam() reads the initial rr0 state.
632 		 */
633 		SET(cs->cs_preg[1], ZSWR1_RIE | ZSWR1_SIE);
634 
635 		/* Clear PPS capture state on first open. */
636 		zst->zst_ppsmask = 0;
637 		zst->ppsparam.mode = 0;
638 
639 		simple_unlock(&cs->cs_lock);
640 		splx(s2);
641 
642 		/* Make sure zsparam will see changes. */
643 		tp->t_ospeed = 0;
644 		(void) zsparam(tp, &t);
645 
646 		/*
647 		 * Note: zsparam has done: cflag, ispeed, ospeed
648 		 * so we just need to do: iflag, oflag, lflag, cc
649 		 * For "raw" mode, just leave all zeros.
650 		 */
651 		if (!ISSET(zst->zst_hwflags, ZS_HWFLAG_RAW)) {
652 			tp->t_iflag = TTYDEF_IFLAG;
653 			tp->t_oflag = TTYDEF_OFLAG;
654 			tp->t_lflag = TTYDEF_LFLAG;
655 		} else {
656 			tp->t_iflag = 0;
657 			tp->t_oflag = 0;
658 			tp->t_lflag = 0;
659 		}
660 		ttychars(tp);
661 		ttsetwater(tp);
662 
663 		s2 = splzs();
664 		simple_lock(&cs->cs_lock);
665 
666 		/*
667 		 * Turn on DTR.  We must always do this, even if carrier is not
668 		 * present, because otherwise we'd have to use TIOCSDTR
669 		 * immediately after setting CLOCAL, which applications do not
670 		 * expect.  We always assert DTR while the device is open
671 		 * unless explicitly requested to deassert it.
672 		 */
673 		zs_modem(zst, 1);
674 
675 		/* Clear the input ring, and unblock. */
676 		zst->zst_rbget = zst->zst_rbput = zst->zst_rbuf;
677 		zst->zst_rbavail = zstty_rbuf_size;
678 		zs_iflush(cs);
679 		CLR(zst->zst_rx_flags, RX_ANY_BLOCK);
680 		zs_hwiflow(zst);
681 
682 		simple_unlock(&cs->cs_lock);
683 		splx(s2);
684 	}
685 
686 	splx(s);
687 
688 	error = ttyopen(tp, ZSDIALOUT(dev), ISSET(flags, O_NONBLOCK));
689 	if (error)
690 		goto bad;
691 
692 	error = (*tp->t_linesw->l_open)(dev, tp);
693 	if (error)
694 		goto bad;
695 
696 	return (0);
697 
698 bad:
699 	if (!ISSET(tp->t_state, TS_ISOPEN) && tp->t_wopen == 0) {
700 		/*
701 		 * We failed to open the device, and nobody else had it opened.
702 		 * Clean up the state as appropriate.
703 		 */
704 		zs_shutdown(zst);
705 	}
706 
707 	return (error);
708 }
709 
710 /*
711  * Close a zs serial port.
712  */
713 int
714 zsclose(dev, flags, mode, l)
715 	dev_t dev;
716 	int flags;
717 	int mode;
718 	struct lwp *l;
719 {
720 	struct zstty_softc *zst = device_lookup(&zstty_cd, ZSUNIT(dev));
721 	struct tty *tp = zst->zst_tty;
722 
723 	/* XXX This is for cons.c. */
724 	if (!ISSET(tp->t_state, TS_ISOPEN))
725 		return 0;
726 
727 	(*tp->t_linesw->l_close)(tp, flags);
728 	ttyclose(tp);
729 
730 	if (!ISSET(tp->t_state, TS_ISOPEN) && tp->t_wopen == 0) {
731 		/*
732 		 * Although we got a last close, the device may still be in
733 		 * use; e.g. if this was the dialout node, and there are still
734 		 * processes waiting for carrier on the non-dialout node.
735 		 */
736 		zs_shutdown(zst);
737 	}
738 
739 	return (0);
740 }
741 
742 /*
743  * Read/write zs serial port.
744  */
745 int
746 zsread(dev, uio, flags)
747 	dev_t dev;
748 	struct uio *uio;
749 	int flags;
750 {
751 	struct zstty_softc *zst = device_lookup(&zstty_cd, ZSUNIT(dev));
752 	struct tty *tp = zst->zst_tty;
753 
754 	return ((*tp->t_linesw->l_read)(tp, uio, flags));
755 }
756 
757 int
758 zswrite(dev, uio, flags)
759 	dev_t dev;
760 	struct uio *uio;
761 	int flags;
762 {
763 	struct zstty_softc *zst = device_lookup(&zstty_cd, ZSUNIT(dev));
764 	struct tty *tp = zst->zst_tty;
765 
766 	return ((*tp->t_linesw->l_write)(tp, uio, flags));
767 }
768 
769 int
770 zspoll(dev, events, l)
771 	dev_t dev;
772 	int events;
773 	struct lwp *l;
774 {
775 	struct zstty_softc *zst = device_lookup(&zstty_cd, ZSUNIT(dev));
776 	struct tty *tp = zst->zst_tty;
777 
778 	return ((*tp->t_linesw->l_poll)(tp, events, l));
779 }
780 
781 int
782 zsioctl(dev, cmd, data, flag, l)
783 	dev_t dev;
784 	u_long cmd;
785 	caddr_t data;
786 	int flag;
787 	struct lwp *l;
788 {
789 	struct zstty_softc *zst = device_lookup(&zstty_cd, ZSUNIT(dev));
790 	struct zs_chanstate *cs = zst->zst_cs;
791 	struct tty *tp = zst->zst_tty;
792 	struct proc *p = l->l_proc;
793 	int error;
794 	int s;
795 
796 	error = (*tp->t_linesw->l_ioctl)(tp, cmd, data, flag, l);
797 	if (error != EPASSTHROUGH)
798 		return (error);
799 
800 	error = ttioctl(tp, cmd, data, flag, l);
801 	if (error != EPASSTHROUGH)
802 		return (error);
803 
804 #ifdef	ZS_MD_IOCTL
805 	error = ZS_MD_IOCTL(cs, cmd, data);
806 	if (error != EPASSTHROUGH)
807 		return (error);
808 #endif	/* ZS_MD_IOCTL */
809 
810 	error = 0;
811 
812 	s = splzs();
813 	simple_lock(&cs->cs_lock);
814 
815 	switch (cmd) {
816 	case TIOCSBRK:
817 		zs_break(cs, 1);
818 		break;
819 
820 	case TIOCCBRK:
821 		zs_break(cs, 0);
822 		break;
823 
824 	case TIOCGFLAGS:
825 		*(int *)data = zst->zst_swflags;
826 		break;
827 
828 	case TIOCSFLAGS:
829 		error = suser(p->p_ucred, &p->p_acflag);
830 		if (error)
831 			break;
832 		zst->zst_swflags = *(int *)data;
833 		break;
834 
835 	case TIOCSDTR:
836 		zs_modem(zst, 1);
837 		break;
838 
839 	case TIOCCDTR:
840 		zs_modem(zst, 0);
841 		break;
842 
843 	case TIOCMSET:
844 	case TIOCMBIS:
845 	case TIOCMBIC:
846 		tiocm_to_zs(zst, cmd, *(int *)data);
847 		break;
848 
849 	case TIOCMGET:
850 		*(int *)data = zs_to_tiocm(zst);
851 		break;
852 
853 	case PPS_IOC_CREATE:
854 		break;
855 
856 	case PPS_IOC_DESTROY:
857 		break;
858 
859 	case PPS_IOC_GETPARAMS: {
860 		pps_params_t *pp;
861 		pp = (pps_params_t *)data;
862 		*pp = zst->ppsparam;
863 		break;
864 	}
865 
866 	case PPS_IOC_SETPARAMS: {
867 		pps_params_t *pp;
868 		int mode;
869 		if (cs->cs_rr0_pps == 0) {
870 			error = EINVAL;
871 			break;
872 		}
873 		pp = (pps_params_t *)data;
874 		if (pp->mode & ~zsppscap) {
875 			error = EINVAL;
876 			break;
877 		}
878 		zst->ppsparam = *pp;
879 		/*
880 		 * compute masks from user-specified timestamp state.
881 		 */
882 		mode = zst->ppsparam.mode;
883 		switch (mode & PPS_CAPTUREBOTH) {
884 		case 0:
885 			zst->zst_ppsmask = 0;
886 			break;
887 
888 		case PPS_CAPTUREASSERT:
889 			zst->zst_ppsmask = ZSRR0_DCD;
890 			zst->zst_ppsassert = ZSRR0_DCD;
891 			zst->zst_ppsclear = -1;
892 			break;
893 
894 		case PPS_CAPTURECLEAR:
895 			zst->zst_ppsmask = ZSRR0_DCD;
896 			zst->zst_ppsassert = -1;
897 			zst->zst_ppsclear = 0;
898 			break;
899 
900 		case PPS_CAPTUREBOTH:
901 			zst->zst_ppsmask = ZSRR0_DCD;
902 			zst->zst_ppsassert = ZSRR0_DCD;
903 			zst->zst_ppsclear = 0;
904 			break;
905 
906 		default:
907 			error = EINVAL;
908 			break;
909 		}
910 
911 		/*
912 		 * Now update interrupts.
913 		 */
914 		zs_maskintr(zst);
915 		/*
916 		 * If nothing is being transmitted, set up new current values,
917 		 * else mark them as pending.
918 		 */
919 		if (!cs->cs_heldchange) {
920 			if (zst->zst_tx_busy) {
921 				zst->zst_heldtbc = zst->zst_tbc;
922 				zst->zst_tbc = 0;
923 				cs->cs_heldchange = 1;
924 			} else
925 				zs_loadchannelregs(cs);
926 		}
927 
928 		break;
929 	}
930 
931 	case PPS_IOC_GETCAP:
932 		*(int *)data = zsppscap;
933 		break;
934 
935 	case PPS_IOC_FETCH: {
936 		pps_info_t *pi;
937 		pi = (pps_info_t *)data;
938 		*pi = zst->ppsinfo;
939 		break;
940 	}
941 
942 #ifdef PPS_SYNC
943 	case PPS_IOC_KCBIND: {
944 		int edge = (*(int *)data) & PPS_CAPTUREBOTH;
945 
946 		if (edge == 0) {
947 			/*
948 			 * remove binding for this source; ignore
949 			 * the request if this is not the current
950 			 * hardpps source
951 			 */
952 			if (pps_kc_hardpps_source == zst) {
953 				pps_kc_hardpps_source = NULL;
954 				pps_kc_hardpps_mode = 0;
955 			}
956 		} else {
957 			/*
958 			 * bind hardpps to this source, replacing any
959 			 * previously specified source or edges
960 			 */
961 			pps_kc_hardpps_source = zst;
962 			pps_kc_hardpps_mode = edge;
963 		}
964 		break;
965 	}
966 #endif /* PPS_SYNC */
967 
968 	case TIOCDCDTIMESTAMP:	/* XXX old, overloaded  API used by xntpd v3 */
969 		if (cs->cs_rr0_pps == 0) {
970 			error = EINVAL;
971 			break;
972 		}
973 		/*
974 		 * Some GPS clocks models use the falling rather than
975 		 * rising edge as the on-the-second signal.
976 		 * The old API has no way to specify PPS polarity.
977 		 */
978 		zst->zst_ppsmask = ZSRR0_DCD;
979 #ifndef	PPS_TRAILING_EDGE
980 		zst->zst_ppsassert = ZSRR0_DCD;
981 		zst->zst_ppsclear = -1;
982 		TIMESPEC_TO_TIMEVAL((struct timeval *)data,
983 			&zst->ppsinfo.assert_timestamp);
984 #else
985 		zst->zst_ppsassert = -1;
986 		zst->zst_ppsclear = 01;
987 		TIMESPEC_TO_TIMEVAL((struct timeval *)data,
988 			&zst->ppsinfo.clear_timestamp);
989 #endif
990 		/*
991 		 * Now update interrupts.
992 		 */
993 		zs_maskintr(zst);
994 		/*
995 		 * If nothing is being transmitted, set up new current values,
996 		 * else mark them as pending.
997 		 */
998 		if (!cs->cs_heldchange) {
999 			if (zst->zst_tx_busy) {
1000 				zst->zst_heldtbc = zst->zst_tbc;
1001 				zst->zst_tbc = 0;
1002 				cs->cs_heldchange = 1;
1003 			} else
1004 				zs_loadchannelregs(cs);
1005 		}
1006 
1007 		break;
1008 
1009 	default:
1010 		error = EPASSTHROUGH;
1011 		break;
1012 	}
1013 
1014 	simple_unlock(&cs->cs_lock);
1015 	splx(s);
1016 
1017 	return (error);
1018 }
1019 
1020 /*
1021  * Start or restart transmission.
1022  */
1023 static void
1024 zsstart(tp)
1025 	struct tty *tp;
1026 {
1027 	struct zstty_softc *zst = device_lookup(&zstty_cd, ZSUNIT(tp->t_dev));
1028 	struct zs_chanstate *cs = zst->zst_cs;
1029 	int s;
1030 
1031 	s = spltty();
1032 	if (ISSET(tp->t_state, TS_BUSY | TS_TIMEOUT | TS_TTSTOP))
1033 		goto out;
1034 	if (zst->zst_tx_stopped)
1035 		goto out;
1036 
1037 	if (tp->t_outq.c_cc <= tp->t_lowat) {
1038 		if (ISSET(tp->t_state, TS_ASLEEP)) {
1039 			CLR(tp->t_state, TS_ASLEEP);
1040 			wakeup((caddr_t)&tp->t_outq);
1041 		}
1042 		selwakeup(&tp->t_wsel);
1043 		if (tp->t_outq.c_cc == 0)
1044 			goto out;
1045 	}
1046 
1047 	/* Grab the first contiguous region of buffer space. */
1048 	{
1049 		u_char *tba;
1050 		int tbc;
1051 
1052 		tba = tp->t_outq.c_cf;
1053 		tbc = ndqb(&tp->t_outq, 0);
1054 
1055 		(void) splzs();
1056 		simple_lock(&cs->cs_lock);
1057 
1058 		zst->zst_tba = tba;
1059 		zst->zst_tbc = tbc;
1060 	}
1061 
1062 	SET(tp->t_state, TS_BUSY);
1063 	zst->zst_tx_busy = 1;
1064 
1065 	/* Enable transmit completion interrupts if necessary. */
1066 	if (!ISSET(cs->cs_preg[1], ZSWR1_TIE)) {
1067 		SET(cs->cs_preg[1], ZSWR1_TIE);
1068 		cs->cs_creg[1] = cs->cs_preg[1];
1069 		zs_write_reg(cs, 1, cs->cs_creg[1]);
1070 	}
1071 
1072 	/* Output the first character of the contiguous buffer. */
1073 	{
1074 		zs_write_data(cs, *zst->zst_tba);
1075 		zst->zst_tbc--;
1076 		zst->zst_tba++;
1077 	}
1078 	simple_unlock(&cs->cs_lock);
1079 out:
1080 	splx(s);
1081 	return;
1082 }
1083 
1084 /*
1085  * Stop output, e.g., for ^S or output flush.
1086  */
1087 void
1088 zsstop(tp, flag)
1089 	struct tty *tp;
1090 	int flag;
1091 {
1092 	struct zstty_softc *zst = device_lookup(&zstty_cd, ZSUNIT(tp->t_dev));
1093 	int s;
1094 
1095 	s = splzs();
1096 	if (ISSET(tp->t_state, TS_BUSY)) {
1097 		/* Stop transmitting at the next chunk. */
1098 		zst->zst_tbc = 0;
1099 		zst->zst_heldtbc = 0;
1100 		if (!ISSET(tp->t_state, TS_TTSTOP))
1101 			SET(tp->t_state, TS_FLUSH);
1102 	}
1103 	splx(s);
1104 }
1105 
1106 /*
1107  * Set ZS tty parameters from termios.
1108  * XXX - Should just copy the whole termios after
1109  * making sure all the changes could be done.
1110  */
1111 static int
1112 zsparam(tp, t)
1113 	struct tty *tp;
1114 	struct termios *t;
1115 {
1116 	struct zstty_softc *zst = device_lookup(&zstty_cd, ZSUNIT(tp->t_dev));
1117 	struct zs_chanstate *cs = zst->zst_cs;
1118 	int ospeed;
1119 	tcflag_t cflag;
1120 	u_char tmp3, tmp4, tmp5;
1121 	int s, error;
1122 
1123 	ospeed = t->c_ospeed;
1124 	cflag = t->c_cflag;
1125 
1126 	/* Check requested parameters. */
1127 	if (ospeed < 0)
1128 		return (EINVAL);
1129 	if (t->c_ispeed && t->c_ispeed != ospeed)
1130 		return (EINVAL);
1131 
1132 	/*
1133 	 * For the console, always force CLOCAL and !HUPCL, so that the port
1134 	 * is always active.
1135 	 */
1136 	if (ISSET(zst->zst_swflags, TIOCFLAG_SOFTCAR) ||
1137 	    ISSET(zst->zst_hwflags, ZS_HWFLAG_CONSOLE)) {
1138 		SET(cflag, CLOCAL);
1139 		CLR(cflag, HUPCL);
1140 	}
1141 
1142 	/*
1143 	 * Only whack the UART when params change.
1144 	 * Some callers need to clear tp->t_ospeed
1145 	 * to make sure initialization gets done.
1146 	 */
1147 	if (tp->t_ospeed == ospeed &&
1148 	    tp->t_cflag == cflag)
1149 		return (0);
1150 
1151 	/*
1152 	 * Call MD functions to deal with changed
1153 	 * clock modes or H/W flow control modes.
1154 	 * The BRG divisor is set now. (reg 12,13)
1155 	 */
1156 	error = zs_set_speed(cs, ospeed);
1157 	if (error)
1158 		return (error);
1159 	error = zs_set_modes(cs, cflag);
1160 	if (error)
1161 		return (error);
1162 
1163 	/*
1164 	 * Block interrupts so that state will not
1165 	 * be altered until we are done setting it up.
1166 	 *
1167 	 * Initial values in cs_preg are set before
1168 	 * our attach routine is called.  The master
1169 	 * interrupt enable is handled by zsc.c
1170 	 *
1171 	 */
1172 	s = splzs();
1173 	simple_lock(&cs->cs_lock);
1174 
1175 	/*
1176 	 * Recalculate which status ints to enable.
1177 	 */
1178 	zs_maskintr(zst);
1179 
1180 	/* Recompute character size bits. */
1181 	tmp3 = cs->cs_preg[3];
1182 	tmp5 = cs->cs_preg[5];
1183 	CLR(tmp3, ZSWR3_RXSIZE);
1184 	CLR(tmp5, ZSWR5_TXSIZE);
1185 	switch (ISSET(cflag, CSIZE)) {
1186 	case CS5:
1187 		SET(tmp3, ZSWR3_RX_5);
1188 		SET(tmp5, ZSWR5_TX_5);
1189 		break;
1190 	case CS6:
1191 		SET(tmp3, ZSWR3_RX_6);
1192 		SET(tmp5, ZSWR5_TX_6);
1193 		break;
1194 	case CS7:
1195 		SET(tmp3, ZSWR3_RX_7);
1196 		SET(tmp5, ZSWR5_TX_7);
1197 		break;
1198 	case CS8:
1199 		SET(tmp3, ZSWR3_RX_8);
1200 		SET(tmp5, ZSWR5_TX_8);
1201 		break;
1202 	}
1203 	cs->cs_preg[3] = tmp3;
1204 	cs->cs_preg[5] = tmp5;
1205 
1206 	/*
1207 	 * Recompute the stop bits and parity bits.  Note that
1208 	 * zs_set_speed() may have set clock selection bits etc.
1209 	 * in wr4, so those must preserved.
1210 	 */
1211 	tmp4 = cs->cs_preg[4];
1212 	CLR(tmp4, ZSWR4_SBMASK | ZSWR4_PARMASK);
1213 	if (ISSET(cflag, CSTOPB))
1214 		SET(tmp4, ZSWR4_TWOSB);
1215 	else
1216 		SET(tmp4, ZSWR4_ONESB);
1217 	if (!ISSET(cflag, PARODD))
1218 		SET(tmp4, ZSWR4_EVENP);
1219 	if (ISSET(cflag, PARENB))
1220 		SET(tmp4, ZSWR4_PARENB);
1221 	cs->cs_preg[4] = tmp4;
1222 
1223 	/* And copy to tty. */
1224 	tp->t_ispeed = 0;
1225 	tp->t_ospeed = ospeed;
1226 	tp->t_cflag = cflag;
1227 
1228 	/*
1229 	 * If nothing is being transmitted, set up new current values,
1230 	 * else mark them as pending.
1231 	 */
1232 	if (!cs->cs_heldchange) {
1233 		if (zst->zst_tx_busy) {
1234 			zst->zst_heldtbc = zst->zst_tbc;
1235 			zst->zst_tbc = 0;
1236 			cs->cs_heldchange = 1;
1237 		} else
1238 			zs_loadchannelregs(cs);
1239 	}
1240 
1241 	/*
1242 	 * If hardware flow control is disabled, turn off the buffer water
1243 	 * marks and unblock any soft flow control state.  Otherwise, enable
1244 	 * the water marks.
1245 	 */
1246 	if (!ISSET(cflag, CHWFLOW)) {
1247 		zst->zst_r_hiwat = 0;
1248 		zst->zst_r_lowat = 0;
1249 		if (ISSET(zst->zst_rx_flags, RX_TTY_OVERFLOWED)) {
1250 			CLR(zst->zst_rx_flags, RX_TTY_OVERFLOWED);
1251 			zst->zst_rx_ready = 1;
1252 			cs->cs_softreq = 1;
1253 		}
1254 		if (ISSET(zst->zst_rx_flags, RX_TTY_BLOCKED|RX_IBUF_BLOCKED)) {
1255 			CLR(zst->zst_rx_flags, RX_TTY_BLOCKED|RX_IBUF_BLOCKED);
1256 			zs_hwiflow(zst);
1257 		}
1258 	} else {
1259 		zst->zst_r_hiwat = zstty_rbuf_hiwat;
1260 		zst->zst_r_lowat = zstty_rbuf_lowat;
1261 	}
1262 
1263 	/*
1264 	 * Force a recheck of the hardware carrier and flow control status,
1265 	 * since we may have changed which bits we're looking at.
1266 	 */
1267 	zstty_stint(cs, 1);
1268 
1269 	simple_unlock(&cs->cs_lock);
1270 	splx(s);
1271 
1272 	/*
1273 	 * If hardware flow control is disabled, unblock any hard flow control
1274 	 * state.
1275 	 */
1276 	if (!ISSET(cflag, CHWFLOW)) {
1277 		if (zst->zst_tx_stopped) {
1278 			zst->zst_tx_stopped = 0;
1279 			zsstart(tp);
1280 		}
1281 	}
1282 
1283 	zstty_softint(cs);
1284 
1285 	return (0);
1286 }
1287 
1288 /*
1289  * Compute interrupt enable bits and set in the pending bits. Called both
1290  * in zsparam() and when PPS (pulse per second timing) state changes.
1291  * Must be called at splzs().
1292  */
1293 static void
1294 zs_maskintr(zst)
1295 	struct zstty_softc *zst;
1296 {
1297 	struct zs_chanstate *cs = zst->zst_cs;
1298 	int tmp15;
1299 
1300 	cs->cs_rr0_mask = cs->cs_rr0_cts | cs->cs_rr0_dcd;
1301 	if (zst->zst_ppsmask != 0)
1302 		cs->cs_rr0_mask |= cs->cs_rr0_pps;
1303 	tmp15 = cs->cs_preg[15];
1304 	if (ISSET(cs->cs_rr0_mask, ZSRR0_DCD))
1305 		SET(tmp15, ZSWR15_DCD_IE);
1306 	else
1307 		CLR(tmp15, ZSWR15_DCD_IE);
1308 	if (ISSET(cs->cs_rr0_mask, ZSRR0_CTS))
1309 		SET(tmp15, ZSWR15_CTS_IE);
1310 	else
1311 		CLR(tmp15, ZSWR15_CTS_IE);
1312 	cs->cs_preg[15] = tmp15;
1313 }
1314 
1315 
1316 /*
1317  * Raise or lower modem control (DTR/RTS) signals.  If a character is
1318  * in transmission, the change is deferred.
1319  * Called at splzs() and with the channel lock held.
1320  */
1321 static void
1322 zs_modem(zst, onoff)
1323 	struct zstty_softc *zst;
1324 	int onoff;
1325 {
1326 	struct zs_chanstate *cs = zst->zst_cs, *ccs;
1327 
1328 	if (cs->cs_wr5_dtr == 0)
1329 		return;
1330 
1331 	ccs = (cs->cs_ctl_chan != NULL ? cs->cs_ctl_chan : cs);
1332 
1333 	if (onoff)
1334 		SET(ccs->cs_preg[5], cs->cs_wr5_dtr);
1335 	else
1336 		CLR(ccs->cs_preg[5], cs->cs_wr5_dtr);
1337 
1338 	if (!cs->cs_heldchange) {
1339 		if (zst->zst_tx_busy) {
1340 			zst->zst_heldtbc = zst->zst_tbc;
1341 			zst->zst_tbc = 0;
1342 			cs->cs_heldchange = 1;
1343 		} else
1344 			zs_loadchannelregs(cs);
1345 	}
1346 }
1347 
1348 /*
1349  * Set modem bits.
1350  * Called at splzs() and with the channel lock held.
1351  */
1352 static void
1353 tiocm_to_zs(zst, how, ttybits)
1354 	struct zstty_softc *zst;
1355 	u_long how;
1356 	int ttybits;
1357 {
1358 	struct zs_chanstate *cs = zst->zst_cs, *ccs;
1359 	u_char zsbits;
1360 
1361 	ccs = (cs->cs_ctl_chan != NULL ? cs->cs_ctl_chan : cs);
1362 
1363 	zsbits = 0;
1364 	if (ISSET(ttybits, TIOCM_DTR))
1365 		SET(zsbits, ZSWR5_DTR);
1366 	if (ISSET(ttybits, TIOCM_RTS))
1367 		SET(zsbits, ZSWR5_RTS);
1368 
1369 	switch (how) {
1370 	case TIOCMBIC:
1371 		CLR(ccs->cs_preg[5], zsbits);
1372 		break;
1373 
1374 	case TIOCMBIS:
1375 		SET(ccs->cs_preg[5], zsbits);
1376 		break;
1377 
1378 	case TIOCMSET:
1379 		CLR(ccs->cs_preg[5], ZSWR5_RTS | ZSWR5_DTR);
1380 		SET(ccs->cs_preg[5], zsbits);
1381 		break;
1382 	}
1383 
1384 	if (!cs->cs_heldchange) {
1385 		if (zst->zst_tx_busy) {
1386 			zst->zst_heldtbc = zst->zst_tbc;
1387 			zst->zst_tbc = 0;
1388 			cs->cs_heldchange = 1;
1389 		} else
1390 			zs_loadchannelregs(cs);
1391 	}
1392 }
1393 
1394 /*
1395  * Get modem bits.
1396  * Called at splzs() and with the channel lock held.
1397  */
1398 static int
1399 zs_to_tiocm(zst)
1400 	struct zstty_softc *zst;
1401 {
1402 	struct zs_chanstate *cs = zst->zst_cs, *ccs;
1403 	u_char zsbits;
1404 	int ttybits = 0;
1405 
1406 	ccs = (cs->cs_ctl_chan != NULL ? cs->cs_ctl_chan : cs);
1407 
1408 	zsbits = ccs->cs_preg[5];
1409 	if (ISSET(zsbits, ZSWR5_DTR))
1410 		SET(ttybits, TIOCM_DTR);
1411 	if (ISSET(zsbits, ZSWR5_RTS))
1412 		SET(ttybits, TIOCM_RTS);
1413 
1414 	zsbits = cs->cs_rr0;
1415 	if (ISSET(zsbits, ZSRR0_DCD))
1416 		SET(ttybits, TIOCM_CD);
1417 	if (ISSET(zsbits, ZSRR0_CTS))
1418 		SET(ttybits, TIOCM_CTS);
1419 
1420 	return (ttybits);
1421 }
1422 
1423 /*
1424  * Try to block or unblock input using hardware flow-control.
1425  * This is called by kern/tty.c if MDMBUF|CRTSCTS is set, and
1426  * if this function returns non-zero, the TS_TBLOCK flag will
1427  * be set or cleared according to the "block" arg passed.
1428  */
1429 int
1430 zshwiflow(tp, block)
1431 	struct tty *tp;
1432 	int block;
1433 {
1434 	struct zstty_softc *zst = device_lookup(&zstty_cd, ZSUNIT(tp->t_dev));
1435 	struct zs_chanstate *cs = zst->zst_cs;
1436 	int s;
1437 
1438 	if (cs->cs_wr5_rts == 0)
1439 		return (0);
1440 
1441 	s = splzs();
1442 	simple_lock(&cs->cs_lock);
1443 	if (block) {
1444 		if (!ISSET(zst->zst_rx_flags, RX_TTY_BLOCKED)) {
1445 			SET(zst->zst_rx_flags, RX_TTY_BLOCKED);
1446 			zs_hwiflow(zst);
1447 		}
1448 	} else {
1449 		if (ISSET(zst->zst_rx_flags, RX_TTY_OVERFLOWED)) {
1450 			CLR(zst->zst_rx_flags, RX_TTY_OVERFLOWED);
1451 			zst->zst_rx_ready = 1;
1452 			cs->cs_softreq = 1;
1453 		}
1454 		if (ISSET(zst->zst_rx_flags, RX_TTY_BLOCKED)) {
1455 			CLR(zst->zst_rx_flags, RX_TTY_BLOCKED);
1456 			zs_hwiflow(zst);
1457 		}
1458 	}
1459 	simple_unlock(&cs->cs_lock);
1460 	splx(s);
1461 	return (1);
1462 }
1463 
1464 /*
1465  * Internal version of zshwiflow
1466  * Called at splzs() and with the channel lock held.
1467  */
1468 static void
1469 zs_hwiflow(zst)
1470 	struct zstty_softc *zst;
1471 {
1472 	struct zs_chanstate *cs = zst->zst_cs, *ccs;
1473 
1474 	if (cs->cs_wr5_rts == 0)
1475 		return;
1476 
1477 	ccs = (cs->cs_ctl_chan != NULL ? cs->cs_ctl_chan : cs);
1478 
1479 	if (ISSET(zst->zst_rx_flags, RX_ANY_BLOCK)) {
1480 		CLR(ccs->cs_preg[5], cs->cs_wr5_rts);
1481 		CLR(ccs->cs_creg[5], cs->cs_wr5_rts);
1482 	} else {
1483 		SET(ccs->cs_preg[5], cs->cs_wr5_rts);
1484 		SET(ccs->cs_creg[5], cs->cs_wr5_rts);
1485 	}
1486 	zs_write_reg(ccs, 5, ccs->cs_creg[5]);
1487 }
1488 
1489 
1490 /****************************************************************
1491  * Interface to the lower layer (zscc)
1492  ****************************************************************/
1493 
1494 #define	integrate	static inline
1495 integrate void zstty_rxsoft(struct zstty_softc *, struct tty *);
1496 integrate void zstty_txsoft(struct zstty_softc *, struct tty *);
1497 integrate void zstty_stsoft(struct zstty_softc *, struct tty *);
1498 static void zstty_diag(void *);
1499 
1500 /*
1501  * Receiver Ready interrupt.
1502  * Called at splzs() and with the channel lock held.
1503  */
1504 static void
1505 zstty_rxint(cs)
1506 	struct zs_chanstate *cs;
1507 {
1508 	struct zstty_softc *zst = cs->cs_private;
1509 	u_char *put, *end;
1510 	u_int cc;
1511 	u_char rr0, rr1, c;
1512 
1513 	end = zst->zst_ebuf;
1514 	put = zst->zst_rbput;
1515 	cc = zst->zst_rbavail;
1516 
1517 	while (cc > 0) {
1518 		/*
1519 		 * First read the status, because reading the received char
1520 		 * destroys the status of this char.
1521 		 */
1522 		rr1 = zs_read_reg(cs, 1);
1523 		c = zs_read_data(cs);
1524 
1525 		if (ISSET(rr1, ZSRR1_FE | ZSRR1_DO | ZSRR1_PE)) {
1526 			/* Clear the receive error. */
1527 			zs_write_csr(cs, ZSWR0_RESET_ERRORS);
1528 		}
1529 
1530 		cn_check_magic(zst->zst_tty->t_dev, c, zstty_cnm_state);
1531 		put[0] = c;
1532 		put[1] = rr1;
1533 		put += 2;
1534 		if (put >= end)
1535 			put = zst->zst_rbuf;
1536 		cc--;
1537 
1538 		rr0 = zs_read_csr(cs);
1539 		if (!ISSET(rr0, ZSRR0_RX_READY))
1540 			break;
1541 	}
1542 
1543 	/*
1544 	 * Current string of incoming characters ended because
1545 	 * no more data was available or we ran out of space.
1546 	 * Schedule a receive event if any data was received.
1547 	 * If we're out of space, turn off receive interrupts.
1548 	 */
1549 	zst->zst_rbput = put;
1550 	zst->zst_rbavail = cc;
1551 	if (!ISSET(zst->zst_rx_flags, RX_TTY_OVERFLOWED)) {
1552 		zst->zst_rx_ready = 1;
1553 		cs->cs_softreq = 1;
1554 	}
1555 
1556 	/*
1557 	 * See if we are in danger of overflowing a buffer. If
1558 	 * so, use hardware flow control to ease the pressure.
1559 	 */
1560 	if (!ISSET(zst->zst_rx_flags, RX_IBUF_BLOCKED) &&
1561 	    cc < zst->zst_r_hiwat) {
1562 		SET(zst->zst_rx_flags, RX_IBUF_BLOCKED);
1563 		zs_hwiflow(zst);
1564 	}
1565 
1566 	/*
1567 	 * If we're out of space, disable receive interrupts
1568 	 * until the queue has drained a bit.
1569 	 */
1570 	if (!cc) {
1571 		SET(zst->zst_rx_flags, RX_IBUF_OVERFLOWED);
1572 		CLR(cs->cs_preg[1], ZSWR1_RIE);
1573 		cs->cs_creg[1] = cs->cs_preg[1];
1574 		zs_write_reg(cs, 1, cs->cs_creg[1]);
1575 	}
1576 
1577 #if 0
1578 	printf("%xH%04d\n", zst->zst_rx_flags, zst->zst_rbavail);
1579 #endif
1580 }
1581 
1582 /*
1583  * Transmitter Ready interrupt.
1584  * Called at splzs() and with the channel lock held.
1585  */
1586 static void
1587 zstty_txint(cs)
1588 	struct zs_chanstate *cs;
1589 {
1590 	struct zstty_softc *zst = cs->cs_private;
1591 
1592 	/*
1593 	 * If we've delayed a parameter change, do it now, and restart
1594 	 * output.
1595 	 */
1596 	if (cs->cs_heldchange) {
1597 		zs_loadchannelregs(cs);
1598 		cs->cs_heldchange = 0;
1599 		zst->zst_tbc = zst->zst_heldtbc;
1600 		zst->zst_heldtbc = 0;
1601 	}
1602 
1603 	/* Output the next character in the buffer, if any. */
1604 	if (zst->zst_tbc > 0) {
1605 		zs_write_data(cs, *zst->zst_tba);
1606 		zst->zst_tbc--;
1607 		zst->zst_tba++;
1608 	} else {
1609 		/* Disable transmit completion interrupts if necessary. */
1610 		if (ISSET(cs->cs_preg[1], ZSWR1_TIE)) {
1611 			CLR(cs->cs_preg[1], ZSWR1_TIE);
1612 			cs->cs_creg[1] = cs->cs_preg[1];
1613 			zs_write_reg(cs, 1, cs->cs_creg[1]);
1614 		}
1615 		if (zst->zst_tx_busy) {
1616 			zst->zst_tx_busy = 0;
1617 			zst->zst_tx_done = 1;
1618 			cs->cs_softreq = 1;
1619 		}
1620 	}
1621 }
1622 
1623 /*
1624  * Status Change interrupt.
1625  * Called at splzs() and with the channel lock held.
1626  */
1627 static void
1628 zstty_stint(cs, force)
1629 	struct zs_chanstate *cs;
1630 	int force;
1631 {
1632 	struct zstty_softc *zst = cs->cs_private;
1633 	u_char rr0, delta;
1634 
1635 	rr0 = zs_read_csr(cs);
1636 	zs_write_csr(cs, ZSWR0_RESET_STATUS);
1637 
1638 	/*
1639 	 * Check here for console break, so that we can abort
1640 	 * even when interrupts are locking up the machine.
1641 	 */
1642 	if (ISSET(rr0, ZSRR0_BREAK))
1643 		cn_check_magic(zst->zst_tty->t_dev, CNC_BREAK, zstty_cnm_state);
1644 
1645 	if (!force)
1646 		delta = rr0 ^ cs->cs_rr0;
1647 	else
1648 		delta = cs->cs_rr0_mask;
1649 	cs->cs_rr0 = rr0;
1650 
1651 	if (ISSET(delta, cs->cs_rr0_mask)) {
1652 		SET(cs->cs_rr0_delta, delta);
1653 
1654 		/*
1655 		 * Pulse-per-second clock signal on edge of DCD?
1656 		 */
1657 		if (ISSET(delta, zst->zst_ppsmask)) {
1658 			struct timeval tv;
1659 			if (ISSET(rr0, zst->zst_ppsmask) == zst->zst_ppsassert) {
1660 				/* XXX nanotime() */
1661 				microtime(&tv);
1662 				TIMEVAL_TO_TIMESPEC(&tv,
1663 					&zst->ppsinfo.assert_timestamp);
1664 				if (zst->ppsparam.mode & PPS_OFFSETASSERT) {
1665 					timespecadd(&zst->ppsinfo.assert_timestamp,
1666 					    &zst->ppsparam.assert_offset,
1667 					    &zst->ppsinfo.assert_timestamp);
1668 				}
1669 
1670 #ifdef PPS_SYNC
1671 				if (pps_kc_hardpps_source == zst &&
1672 				    pps_kc_hardpps_mode & PPS_CAPTUREASSERT) {
1673 					hardpps(&tv, tv.tv_usec);
1674 				}
1675 #endif
1676 				zst->ppsinfo.assert_sequence++;
1677 				zst->ppsinfo.current_mode = zst->ppsparam.mode;
1678 			} else if (ISSET(rr0, zst->zst_ppsmask) ==
1679 						zst->zst_ppsclear) {
1680 				/* XXX nanotime() */
1681 				microtime(&tv);
1682 				TIMEVAL_TO_TIMESPEC(&tv,
1683 					&zst->ppsinfo.clear_timestamp);
1684 				if (zst->ppsparam.mode & PPS_OFFSETCLEAR) {
1685 					timespecadd(&zst->ppsinfo.clear_timestamp,
1686 						&zst->ppsparam.clear_offset,
1687 						&zst->ppsinfo.clear_timestamp);
1688 				}
1689 
1690 #ifdef PPS_SYNC
1691 				if (pps_kc_hardpps_source == zst &&
1692 				    pps_kc_hardpps_mode & PPS_CAPTURECLEAR) {
1693 					hardpps(&tv, tv.tv_usec);
1694 				}
1695 #endif
1696 				zst->ppsinfo.clear_sequence++;
1697 				zst->ppsinfo.current_mode = zst->ppsparam.mode;
1698 			}
1699 		}
1700 
1701 		/*
1702 		 * Stop output immediately if we lose the output
1703 		 * flow control signal or carrier detect.
1704 		 */
1705 		if (ISSET(~rr0, cs->cs_rr0_mask)) {
1706 			zst->zst_tbc = 0;
1707 			zst->zst_heldtbc = 0;
1708 		}
1709 
1710 		zst->zst_st_check = 1;
1711 		cs->cs_softreq = 1;
1712 	}
1713 }
1714 
1715 void
1716 zstty_diag(arg)
1717 	void *arg;
1718 {
1719 	struct zstty_softc *zst = arg;
1720 	int overflows, floods;
1721 	int s;
1722 
1723 	s = splzs();
1724 	overflows = zst->zst_overflows;
1725 	zst->zst_overflows = 0;
1726 	floods = zst->zst_floods;
1727 	zst->zst_floods = 0;
1728 	zst->zst_errors = 0;
1729 	splx(s);
1730 
1731 	log(LOG_WARNING, "%s: %d silo overflow%s, %d ibuf flood%s\n",
1732 	    zst->zst_dev.dv_xname,
1733 	    overflows, overflows == 1 ? "" : "s",
1734 	    floods, floods == 1 ? "" : "s");
1735 }
1736 
1737 integrate void
1738 zstty_rxsoft(zst, tp)
1739 	struct zstty_softc *zst;
1740 	struct tty *tp;
1741 {
1742 	struct zs_chanstate *cs = zst->zst_cs;
1743 	int (*rint)(int, struct tty *) = tp->t_linesw->l_rint;
1744 	u_char *get, *end;
1745 	u_int cc, scc;
1746 	u_char rr1;
1747 	int code;
1748 	int s;
1749 
1750 	end = zst->zst_ebuf;
1751 	get = zst->zst_rbget;
1752 	scc = cc = zstty_rbuf_size - zst->zst_rbavail;
1753 
1754 	if (cc == zstty_rbuf_size) {
1755 		zst->zst_floods++;
1756 		if (zst->zst_errors++ == 0)
1757 			callout_reset(&zst->zst_diag_ch, 60 * hz,
1758 			    zstty_diag, zst);
1759 	}
1760 
1761 	/* If not yet open, drop the entire buffer content here */
1762 	if (!ISSET(tp->t_state, TS_ISOPEN)) {
1763 		get += cc << 1;
1764 		if (get >= end)
1765 			get -= zstty_rbuf_size << 1;
1766 		cc = 0;
1767 	}
1768 	while (cc) {
1769 		code = get[0];
1770 		rr1 = get[1];
1771 		if (ISSET(rr1, ZSRR1_DO | ZSRR1_FE | ZSRR1_PE)) {
1772 			if (ISSET(rr1, ZSRR1_DO)) {
1773 				zst->zst_overflows++;
1774 				if (zst->zst_errors++ == 0)
1775 					callout_reset(&zst->zst_diag_ch,
1776 					    60 * hz, zstty_diag, zst);
1777 			}
1778 			if (ISSET(rr1, ZSRR1_FE))
1779 				SET(code, TTY_FE);
1780 			if (ISSET(rr1, ZSRR1_PE))
1781 				SET(code, TTY_PE);
1782 		}
1783 		if ((*rint)(code, tp) == -1) {
1784 			/*
1785 			 * The line discipline's buffer is out of space.
1786 			 */
1787 			if (!ISSET(zst->zst_rx_flags, RX_TTY_BLOCKED)) {
1788 				/*
1789 				 * We're either not using flow control, or the
1790 				 * line discipline didn't tell us to block for
1791 				 * some reason.  Either way, we have no way to
1792 				 * know when there's more space available, so
1793 				 * just drop the rest of the data.
1794 				 */
1795 				get += cc << 1;
1796 				if (get >= end)
1797 					get -= zstty_rbuf_size << 1;
1798 				cc = 0;
1799 			} else {
1800 				/*
1801 				 * Don't schedule any more receive processing
1802 				 * until the line discipline tells us there's
1803 				 * space available (through comhwiflow()).
1804 				 * Leave the rest of the data in the input
1805 				 * buffer.
1806 				 */
1807 				SET(zst->zst_rx_flags, RX_TTY_OVERFLOWED);
1808 			}
1809 			break;
1810 		}
1811 		get += 2;
1812 		if (get >= end)
1813 			get = zst->zst_rbuf;
1814 		cc--;
1815 	}
1816 
1817 	if (cc != scc) {
1818 		zst->zst_rbget = get;
1819 		s = splzs();
1820 		simple_lock(&cs->cs_lock);
1821 		cc = zst->zst_rbavail += scc - cc;
1822 		/* Buffers should be ok again, release possible block. */
1823 		if (cc >= zst->zst_r_lowat) {
1824 			if (ISSET(zst->zst_rx_flags, RX_IBUF_OVERFLOWED)) {
1825 				CLR(zst->zst_rx_flags, RX_IBUF_OVERFLOWED);
1826 				SET(cs->cs_preg[1], ZSWR1_RIE);
1827 				cs->cs_creg[1] = cs->cs_preg[1];
1828 				zs_write_reg(cs, 1, cs->cs_creg[1]);
1829 			}
1830 			if (ISSET(zst->zst_rx_flags, RX_IBUF_BLOCKED)) {
1831 				CLR(zst->zst_rx_flags, RX_IBUF_BLOCKED);
1832 				zs_hwiflow(zst);
1833 			}
1834 		}
1835 		simple_unlock(&cs->cs_lock);
1836 		splx(s);
1837 	}
1838 
1839 #if 0
1840 	printf("%xS%04d\n", zst->zst_rx_flags, zst->zst_rbavail);
1841 #endif
1842 }
1843 
1844 integrate void
1845 zstty_txsoft(zst, tp)
1846 	struct zstty_softc *zst;
1847 	struct tty *tp;
1848 {
1849 	struct zs_chanstate *cs = zst->zst_cs;
1850 	int s;
1851 
1852 	s = splzs();
1853 	simple_lock(&cs->cs_lock);
1854 	CLR(tp->t_state, TS_BUSY);
1855 	if (ISSET(tp->t_state, TS_FLUSH))
1856 		CLR(tp->t_state, TS_FLUSH);
1857 	else
1858 		ndflush(&tp->t_outq, (int)(zst->zst_tba - tp->t_outq.c_cf));
1859 	simple_unlock(&cs->cs_lock);
1860 	splx(s);
1861 	(*tp->t_linesw->l_start)(tp);
1862 }
1863 
1864 integrate void
1865 zstty_stsoft(zst, tp)
1866 	struct zstty_softc *zst;
1867 	struct tty *tp;
1868 {
1869 	struct zs_chanstate *cs = zst->zst_cs;
1870 	u_char rr0, delta;
1871 	int s;
1872 
1873 	s = splzs();
1874 	simple_lock(&cs->cs_lock);
1875 	rr0 = cs->cs_rr0;
1876 	delta = cs->cs_rr0_delta;
1877 	cs->cs_rr0_delta = 0;
1878 	simple_unlock(&cs->cs_lock);
1879 	splx(s);
1880 
1881 	if (ISSET(delta, cs->cs_rr0_dcd)) {
1882 		/*
1883 		 * Inform the tty layer that carrier detect changed.
1884 		 */
1885 		(void) (*tp->t_linesw->l_modem)(tp, ISSET(rr0, ZSRR0_DCD));
1886 	}
1887 
1888 	if (ISSET(delta, cs->cs_rr0_cts)) {
1889 		/* Block or unblock output according to flow control. */
1890 		if (ISSET(rr0, cs->cs_rr0_cts)) {
1891 			zst->zst_tx_stopped = 0;
1892 			(*tp->t_linesw->l_start)(tp);
1893 		} else {
1894 			zst->zst_tx_stopped = 1;
1895 		}
1896 	}
1897 }
1898 
1899 /*
1900  * Software interrupt.  Called at zssoft
1901  *
1902  * The main job to be done here is to empty the input ring
1903  * by passing its contents up to the tty layer.  The ring is
1904  * always emptied during this operation, therefore the ring
1905  * must not be larger than the space after "high water" in
1906  * the tty layer, or the tty layer might drop our input.
1907  *
1908  * Note: an "input blockage" condition is assumed to exist if
1909  * EITHER the TS_TBLOCK flag or zst_rx_blocked flag is set.
1910  */
1911 static void
1912 zstty_softint(cs)
1913 	struct zs_chanstate *cs;
1914 {
1915 	struct zstty_softc *zst = cs->cs_private;
1916 	struct tty *tp = zst->zst_tty;
1917 	int s;
1918 
1919 	s = spltty();
1920 
1921 	if (zst->zst_rx_ready) {
1922 		zst->zst_rx_ready = 0;
1923 		zstty_rxsoft(zst, tp);
1924 	}
1925 
1926 	if (zst->zst_st_check) {
1927 		zst->zst_st_check = 0;
1928 		zstty_stsoft(zst, tp);
1929 	}
1930 
1931 	if (zst->zst_tx_done) {
1932 		zst->zst_tx_done = 0;
1933 		zstty_txsoft(zst, tp);
1934 	}
1935 
1936 	splx(s);
1937 }
1938 
1939 struct zsops zsops_tty = {
1940 	zstty_rxint,	/* receive char available */
1941 	zstty_stint,	/* external/status */
1942 	zstty_txint,	/* xmit buffer empty */
1943 	zstty_softint,	/* process software interrupt */
1944 };
1945