xref: /netbsd-src/sys/arch/atari/dev/zs.c (revision 08c81a9c2dc8c7300e893321eb65c0925d60871c)
1 /*	$NetBSD: zs.c,v 1.36 2002/09/06 13:18:43 gehenna Exp $	*/
2 
3 /*
4  * Copyright (c) 1995 L. Weppelman (Atari modifications)
5  * Copyright (c) 1992, 1993
6  *	The Regents of the University of California.  All rights reserved.
7  *
8  * This software was developed by the Computer Systems Engineering group
9  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
10  * contributed to Berkeley.
11  *
12  *
13  * All advertising materials mentioning features or use of this software
14  * must display the following acknowledgement:
15  *	This product includes software developed by the University of
16  *	California, Lawrence Berkeley Laboratory.
17  *
18  * Redistribution and use in source and binary forms, with or without
19  * modification, are permitted provided that the following conditions
20  * are met:
21  * 1. Redistributions of source code must retain the above copyright
22  *    notice, this list of conditions and the following disclaimer.
23  * 2. Redistributions in binary form must reproduce the above copyright
24  *    notice, this list of conditions and the following disclaimer in the
25  *    documentation and/or other materials provided with the distribution.
26  * 3. All advertising materials mentioning features or use of this software
27  *    must display the following acknowledgement:
28  *	This product includes software developed by the University of
29  *	California, Berkeley and its contributors.
30  * 4. Neither the name of the University nor the names of its contributors
31  *    may be used to endorse or promote products derived from this software
32  *    without specific prior written permission.
33  *
34  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
35  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
36  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
37  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
38  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
39  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
40  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
41  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
42  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
43  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
44  * SUCH DAMAGE.
45  *
46  *	@(#)zs.c	8.1 (Berkeley) 7/19/93
47  */
48 
49 /*
50  * Zilog Z8530 (ZSCC) driver.
51  *
52  * Runs two tty ports (modem2 and serial2) on zs0.
53  *
54  * This driver knows far too much about chip to usage mappings.
55  */
56 #include <sys/param.h>
57 #include <sys/systm.h>
58 #include <sys/proc.h>
59 #include <sys/device.h>
60 #include <sys/conf.h>
61 #include <sys/file.h>
62 #include <sys/ioctl.h>
63 #include <sys/malloc.h>
64 #include <sys/tty.h>
65 #include <sys/time.h>
66 #include <sys/kernel.h>
67 #include <sys/syslog.h>
68 
69 #include <machine/cpu.h>
70 #include <machine/iomap.h>
71 #include <machine/scu.h>
72 #include <machine/mfp.h>
73 #include <atari/dev/ym2149reg.h>
74 
75 #include <dev/ic/z8530reg.h>
76 #include <atari/dev/zsvar.h>
77 #include "zs.h"
78 #if NZS > 1
79 #error "This driver supports only 1 85C30!"
80 #endif
81 
82 #if NZS > 0
83 
84 #define PCLK	(8053976)	/* PCLK pin input clock rate */
85 #define PCLK_HD	(9600 * 1536)	/* PCLK on Hades pin input clock rate */
86 
87 #define splzs	spl5
88 
89 /*
90  * Software state per found chip.
91  */
92 struct zs_softc {
93     struct	device		zi_dev;    /* base device		  */
94     volatile struct zsdevice	*zi_zs;    /* chip registers		  */
95     struct	zs_chanstate	zi_cs[2];  /* chan A and B software state */
96 };
97 
98 static u_char	cb_scheduled = 0;	/* Already asked for callback? */
99 /*
100  * Define the registers for a closed port
101  */
102 static u_char zs_init_regs[16] = {
103 /*  0 */	0,
104 /*  1 */	0,
105 /*  2 */	0x60,
106 /*  3 */	0,
107 /*  4 */	0,
108 /*  5 */	0,
109 /*  6 */	0,
110 /*  7 */	0,
111 /*  8 */	0,
112 /*  9 */	ZSWR9_MASTER_IE | ZSWR9_VECTOR_INCL_STAT,
113 /* 10 */	ZSWR10_NRZ,
114 /* 11 */	ZSWR11_TXCLK_BAUD | ZSWR11_RXCLK_BAUD,
115 /* 12 */	0,
116 /* 13 */	0,
117 /* 14 */	ZSWR14_BAUD_FROM_PCLK | ZSWR14_BAUD_ENA,
118 /* 15 */	0
119 };
120 
121 /*
122  * Define the machine dependant clock frequencies
123  * If BRgen feeds sender/receiver we always use a
124  * divisor 16, therefor the division by 16 can as
125  * well be done here.
126  */
127 static u_long zs_freqs_tt[] = {
128 	/*
129 	 * Atari TT, RTxCB is generated by TT-MFP timer C,
130 	 * which is set to 307.2KHz during initialisation
131 	 * and never changed afterwards.
132 	 */
133 	PCLK/16,	/* BRgen, PCLK,  divisor 16	*/
134 	 229500,	/* BRgen, RTxCA, divisor 16	*/
135 	3672000,	/* RTxCA, from PCLK4		*/
136 	      0,	/* TRxCA, external		*/
137 
138 	PCLK/16,	/* BRgen, PCLK,  divisor 16	*/
139 	  19200,	/* BRgen, RTxCB, divisor 16	*/
140 	 307200,	/* RTxCB, from TT-MFP TCO	*/
141 	2457600		/* TRxCB, from BCLK		*/
142 };
143 
144 static u_long zs_freqs_falcon[] = {
145 	/*
146 	 * Atari Falcon, XXX no specs available, this might be wrong
147 	 */
148 	PCLK/16,	/* BRgen, PCLK,  divisor 16	*/
149 	 229500,	/* BRgen, RTxCA, divisor 16	*/
150 	3672000,	/* RTxCA, ???			*/
151 	      0,	/* TRxCA, external		*/
152 
153 	PCLK/16,	/* BRgen, PCLK,  divisor 16	*/
154 	 229500,	/* BRgen, RTxCB, divisor 16	*/
155 	3672000,	/* RTxCB, ???			*/
156 	2457600		/* TRxCB, ???			*/
157 };
158 
159 static u_long zs_freqs_hades[] = {
160 	/*
161 	 * XXX: Channel-A unchecked!!!!!
162 	 */
163      PCLK_HD/16,	/* BRgen, PCLK,  divisor 16	*/
164 	 229500,	/* BRgen, RTxCA, divisor 16	*/
165 	3672000,	/* RTxCA, from PCLK4		*/
166 	      0,	/* TRxCA, external		*/
167 
168      PCLK_HD/16,	/* BRgen, PCLK,  divisor 16	*/
169 	 235550,	/* BRgen, RTxCB, divisor 16	*/
170 	3768800,	/* RTxCB, 3.7688MHz		*/
171 	3768800		/* TRxCB, 3.7688MHz		*/
172 };
173 
174 static u_long zs_freqs_generic[] = {
175 	/*
176 	 * other machines, assume only PCLK is available
177 	 */
178 	PCLK/16,	/* BRgen, PCLK,  divisor 16	*/
179 	      0,	/* BRgen, RTxCA, divisor 16	*/
180 	      0,	/* RTxCA, unknown		*/
181 	      0,	/* TRxCA, unknown		*/
182 
183 	PCLK/16,	/* BRgen, PCLK,  divisor 16	*/
184 	      0,	/* BRgen, RTxCB, divisor 16	*/
185 	      0,	/* RTxCB, unknown		*/
186 	      0		/* TRxCB, unknown		*/
187 };
188 static u_long *zs_frequencies;
189 
190 /* Definition of the driver for autoconfig. */
191 static int	zsmatch __P((struct device *, struct cfdata *, void *));
192 static void	zsattach __P((struct device *, struct device *, void *));
193 
194 struct cfattach zs_ca = {
195 	sizeof(struct zs_softc), zsmatch, zsattach
196 };
197 
198 extern struct cfdriver zs_cd;
199 
200 /* {b,c}devsw[] function prototypes */
201 dev_type_open(zsopen);
202 dev_type_close(zsclose);
203 dev_type_read(zsread);
204 dev_type_write(zswrite);
205 dev_type_ioctl(zsioctl);
206 dev_type_stop(zsstop);
207 dev_type_tty(zstty);
208 dev_type_poll(zspoll);
209 
210 const struct cdevsw zs_cdevsw = {
211 	zsopen, zsclose, zsread, zswrite, zsioctl,
212 	zsstop, zstty, zspoll, nommap, D_TTY
213 };
214 
215 /* Interrupt handlers. */
216 int		zshard __P((long));
217 static int	zssoft __P((long));
218 static int	zsrint __P((struct zs_chanstate *, volatile struct zschan *));
219 static int	zsxint __P((struct zs_chanstate *, volatile struct zschan *));
220 static int	zssint __P((struct zs_chanstate *, volatile struct zschan *));
221 
222 static struct zs_chanstate *zslist;
223 
224 /* Routines called from other code. */
225 static void	zsstart __P((struct tty *));
226 
227 /* Routines purely local to this driver. */
228 static void	zsoverrun __P((int, long *, char *));
229 static int	zsparam __P((struct tty *, struct termios *));
230 static int	zsbaudrate __P((int, int, int *, int *, int *, int *));
231 static int	zs_modem __P((struct zs_chanstate *, int, int));
232 static void	zs_loadchannelregs __P((volatile struct zschan *, u_char *));
233 static void	zs_shutdown __P((struct zs_chanstate *));
234 
235 static int zsshortcuts;	/* number of "shortcut" software interrupts */
236 
237 static int
238 zsmatch(pdp, cfp, auxp)
239 struct device	*pdp;
240 struct cfdata	*cfp;
241 void		*auxp;
242 {
243 	static int	zs_matched = 0;
244 
245 	if(strcmp("zs", auxp) || zs_matched)
246 		return(0);
247 	zs_matched = 1;
248 	return(1);
249 }
250 
251 /*
252  * Attach a found zs.
253  */
254 static void
255 zsattach(parent, dev, aux)
256 struct device	*parent;
257 struct device	*dev;
258 void		*aux;
259 {
260 	register struct zs_softc		*zi;
261 	register struct zs_chanstate		*cs;
262 	register volatile struct zsdevice	*addr;
263 		 char				tmp;
264 
265 	addr      = (struct zsdevice *)AD_SCC;
266 	zi        = (struct zs_softc *)dev;
267 	zi->zi_zs = addr;
268 	cs        = zi->zi_cs;
269 
270 	/*
271 	 * Get the command register into a known state.
272 	 */
273 	tmp = addr->zs_chan[ZS_CHAN_A].zc_csr;
274 	tmp = addr->zs_chan[ZS_CHAN_A].zc_csr;
275 	tmp = addr->zs_chan[ZS_CHAN_B].zc_csr;
276 	tmp = addr->zs_chan[ZS_CHAN_B].zc_csr;
277 
278 	/*
279 	 * Do a hardware reset.
280 	 */
281 	ZS_WRITE(&addr->zs_chan[ZS_CHAN_A], 9, ZSWR9_HARD_RESET);
282 	delay(50000);	/*enough ? */
283 	ZS_WRITE(&addr->zs_chan[ZS_CHAN_A], 9, 0);
284 
285 	/*
286 	 * Initialize both channels
287 	 */
288 	zs_loadchannelregs(&addr->zs_chan[ZS_CHAN_A], zs_init_regs);
289 	zs_loadchannelregs(&addr->zs_chan[ZS_CHAN_B], zs_init_regs);
290 
291 	if(machineid & ATARI_TT) {
292 		/*
293 		 * ininitialise TT-MFP timer C: 307200Hz
294 		 * timer C and D share one control register:
295 		 *	bits 0-2 control timer D
296 		 *	bits 4-6 control timer C
297 		 */
298 		int cr = MFP2->mf_tcdcr & 7;
299 		MFP2->mf_tcdcr = cr;		/* stop timer C  */
300 		MFP2->mf_tcdr  = 1;		/* counter 1     */
301 		cr |= T_Q004 << 4;		/* divisor 4     */
302 		MFP2->mf_tcdcr = cr;		/* start timer C */
303 		/*
304 		 * enable scc related interrupts
305 		 */
306 		SCU->vme_mask |= SCU_SCC;
307 
308 		zs_frequencies = zs_freqs_tt;
309 	} else if (machineid & ATARI_FALCON) {
310 		zs_frequencies = zs_freqs_falcon;
311 	} else if (machineid & ATARI_HADES) {
312 		zs_frequencies = zs_freqs_hades;
313 	} else {
314 		zs_frequencies = zs_freqs_generic;
315 	}
316 
317 	/* link into interrupt list with order (A,B) (B=A+1) */
318 	cs[0].cs_next = &cs[1];
319 	cs[1].cs_next = zslist;
320 	zslist        = cs;
321 
322 	cs->cs_unit  = 0;
323 	cs->cs_zc    = &addr->zs_chan[ZS_CHAN_A];
324 	cs++;
325 	cs->cs_unit  = 1;
326 	cs->cs_zc    = &addr->zs_chan[ZS_CHAN_B];
327 
328 	printf(": serial2 on channel a and modem2 on channel b\n");
329 }
330 
331 /*
332  * Open a zs serial port.
333  */
334 int
335 zsopen(dev, flags, mode, p)
336 dev_t		dev;
337 int		flags;
338 int		mode;
339 struct proc	*p;
340 {
341 	register struct tty		*tp;
342 	register struct zs_chanstate	*cs;
343 		 struct zs_softc	*zi;
344 		 int			unit = ZS_UNIT(dev);
345 		 int			zs = unit >> 1;
346 		 int			error, s;
347 
348 	if(zs >= zs_cd.cd_ndevs || (zi = zs_cd.cd_devs[zs]) == NULL)
349 		return (ENXIO);
350 	cs = &zi->zi_cs[unit & 1];
351 
352 	/*
353 	 * When port A (ser02) is selected on the TT, make sure
354 	 * the port is enabled.
355 	 */
356 	if((machineid & ATARI_TT) && !(unit & 1))
357 		ym2149_ser2(1);
358 
359 	if (cs->cs_rbuf == NULL) {
360 		cs->cs_rbuf = malloc(ZLRB_RING_SIZE * sizeof(int), M_DEVBUF,
361 								   M_WAITOK);
362 	}
363 
364 	tp = cs->cs_ttyp;
365 	if(tp == NULL) {
366 		cs->cs_ttyp = tp = ttymalloc();
367 		tty_attach(tp);
368 		tp->t_dev   = dev;
369 		tp->t_oproc = zsstart;
370 		tp->t_param = zsparam;
371 	}
372 
373 	if ((tp->t_state & TS_ISOPEN) &&
374 	    (tp->t_state & TS_XCLUDE) &&
375 	    p->p_ucred->cr_uid != 0)
376 		return (EBUSY);
377 
378 	s  = spltty();
379 
380 	/*
381 	 * Do the following iff this is a first open.
382 	 */
383 	if (!(tp->t_state & TS_ISOPEN) && tp->t_wopen == 0) {
384 		if(tp->t_ispeed == 0) {
385 			tp->t_iflag = TTYDEF_IFLAG;
386 			tp->t_oflag = TTYDEF_OFLAG;
387 			tp->t_cflag = TTYDEF_CFLAG;
388 			tp->t_lflag = TTYDEF_LFLAG;
389 			tp->t_ispeed = tp->t_ospeed = TTYDEF_SPEED;
390 		}
391 		ttychars(tp);
392 		ttsetwater(tp);
393 
394 		(void)zsparam(tp, &tp->t_termios);
395 
396 		/*
397 		 * Turn on DTR.  We must always do this, even if carrier is not
398 		 * present, because otherwise we'd have to use TIOCSDTR
399 		 * immediately after setting CLOCAL, which applications do not
400 		 * expect.  We always assert DTR while the device is open
401 		 * unless explicitly requested to deassert it.
402 		 */
403 		zs_modem(cs, ZSWR5_RTS|ZSWR5_DTR, DMSET);
404 		/* May never get a status intr. if DCD already on. -gwr */
405 		if((cs->cs_rr0 = cs->cs_zc->zc_csr) & ZSRR0_DCD)
406 			tp->t_state |= TS_CARR_ON;
407 		if(cs->cs_softcar)
408 			tp->t_state |= TS_CARR_ON;
409 	}
410 
411 	splx(s);
412 
413 	error = ttyopen(tp, ZS_DIALOUT(dev), (flags & O_NONBLOCK));
414 	if (error)
415 		goto bad;
416 
417 	error = tp->t_linesw->l_open(dev, tp);
418 	if(error)
419 		goto bad;
420 	return (0);
421 
422 bad:
423 	if (!(tp->t_state & TS_ISOPEN) && tp->t_wopen == 0) {
424 		/*
425 		 * We failed to open the device, and nobody else had it opened.
426 		 * Clean up the state as appropriate.
427 		 */
428 		zs_shutdown(cs);
429 	}
430 	return(error);
431 }
432 
433 /*
434  * Close a zs serial port.
435  */
436 int
437 zsclose(dev, flags, mode, p)
438 dev_t		dev;
439 int		flags;
440 int		mode;
441 struct proc	*p;
442 {
443 	register struct zs_chanstate	*cs;
444 	register struct tty		*tp;
445 		 struct zs_softc	*zi;
446 		 int			unit = ZS_UNIT(dev);
447 
448 	zi = zs_cd.cd_devs[unit >> 1];
449 	cs = &zi->zi_cs[unit & 1];
450 	tp = cs->cs_ttyp;
451 
452 	tp->t_linesw->l_close(tp, flags);
453 	ttyclose(tp);
454 
455 	if (!(tp->t_state & TS_ISOPEN) && tp->t_wopen == 0) {
456 		/*
457 		 * Although we got a last close, the device may still be in
458 		 * use; e.g. if this was the dialout node, and there are still
459 		 * processes waiting for carrier on the non-dialout node.
460 		 */
461 		zs_shutdown(cs);
462 	}
463 	return (0);
464 }
465 
466 /*
467  * Read/write zs serial port.
468  */
469 int
470 zsread(dev, uio, flags)
471 dev_t		dev;
472 struct uio	*uio;
473 int		flags;
474 {
475 	register struct zs_chanstate	*cs;
476 	register struct zs_softc	*zi;
477 	register struct tty		*tp;
478 		 int			unit;
479 
480 	unit = ZS_UNIT(dev);
481 	zi   = zs_cd.cd_devs[unit >> 1];
482 	cs   = &zi->zi_cs[unit & 1];
483 	tp   = cs->cs_ttyp;
484 
485 	return(tp->t_linesw->l_read(tp, uio, flags));
486 }
487 
488 int
489 zswrite(dev, uio, flags)
490 dev_t		dev;
491 struct uio	*uio;
492 int		flags;
493 {
494 	register struct zs_chanstate	*cs;
495 	register struct zs_softc	*zi;
496 	register struct tty		*tp;
497 		 int			unit;
498 
499 	unit = ZS_UNIT(dev);
500 	zi   = zs_cd.cd_devs[unit >> 1];
501 	cs   = &zi->zi_cs[unit & 1];
502 	tp   = cs->cs_ttyp;
503 
504 	return(tp->t_linesw->l_write(tp, uio, flags));
505 }
506 
507 int
508 zspoll(dev, events, p)
509 dev_t		dev;
510 int		events;
511 struct proc	*p;
512 {
513 	register struct zs_chanstate	*cs;
514 	register struct zs_softc	*zi;
515 	register struct tty		*tp;
516 		 int			unit;
517 
518 	unit = ZS_UNIT(dev);
519 	zi   = zs_cd.cd_devs[unit >> 1];
520 	cs   = &zi->zi_cs[unit & 1];
521 	tp   = cs->cs_ttyp;
522 
523 	return ((*tp->t_linesw->l_poll)(tp, events, p));
524 }
525 
526 struct tty *
527 zstty(dev)
528 dev_t	dev;
529 {
530 	register struct zs_chanstate	*cs;
531 	register struct zs_softc	*zi;
532 		 int			unit;
533 
534 	unit = ZS_UNIT(dev);
535 	zi   = zs_cd.cd_devs[unit >> 1];
536 	cs   = &zi->zi_cs[unit & 1];
537 	return(cs->cs_ttyp);
538 }
539 
540 /*
541  * ZS hardware interrupt.  Scan all ZS channels.  NB: we know here that
542  * channels are kept in (A,B) pairs.
543  *
544  * Do just a little, then get out; set a software interrupt if more
545  * work is needed.
546  *
547  * We deliberately ignore the vectoring Zilog gives us, and match up
548  * only the number of `reset interrupt under service' operations, not
549  * the order.
550  */
551 
552 int
553 zshard(sr)
554 long sr;
555 {
556 	register struct zs_chanstate	*a;
557 #define	b (a + 1)
558 	register volatile struct zschan *zc;
559 	register int			rr3, intflags = 0, v, i;
560 
561 	do {
562 	    intflags &= ~4;
563 	    for(a = zslist; a != NULL; a = b->cs_next) {
564 		rr3 = ZS_READ(a->cs_zc, 3);
565 		if(rr3 & (ZSRR3_IP_A_RX|ZSRR3_IP_A_TX|ZSRR3_IP_A_STAT)) {
566 			intflags |= 4|2;
567 			zc = a->cs_zc;
568 			i  = a->cs_rbput;
569 			if(rr3 & ZSRR3_IP_A_RX && (v = zsrint(a, zc)) != 0) {
570 				a->cs_rbuf[i++ & ZLRB_RING_MASK] = v;
571 				intflags |= 1;
572 			}
573 			if(rr3 & ZSRR3_IP_A_TX && (v = zsxint(a, zc)) != 0) {
574 				a->cs_rbuf[i++ & ZLRB_RING_MASK] = v;
575 				intflags |= 1;
576 			}
577 			if(rr3 & ZSRR3_IP_A_STAT && (v = zssint(a, zc)) != 0) {
578 				a->cs_rbuf[i++ & ZLRB_RING_MASK] = v;
579 				intflags |= 1;
580 			}
581 			a->cs_rbput = i;
582 		}
583 		if(rr3 & (ZSRR3_IP_B_RX|ZSRR3_IP_B_TX|ZSRR3_IP_B_STAT)) {
584 			intflags |= 4|2;
585 			zc = b->cs_zc;
586 			i  = b->cs_rbput;
587 			if(rr3 & ZSRR3_IP_B_RX && (v = zsrint(b, zc)) != 0) {
588 				b->cs_rbuf[i++ & ZLRB_RING_MASK] = v;
589 				intflags |= 1;
590 			}
591 			if(rr3 & ZSRR3_IP_B_TX && (v = zsxint(b, zc)) != 0) {
592 				b->cs_rbuf[i++ & ZLRB_RING_MASK] = v;
593 				intflags |= 1;
594 			}
595 			if(rr3 & ZSRR3_IP_B_STAT && (v = zssint(b, zc)) != 0) {
596 				b->cs_rbuf[i++ & ZLRB_RING_MASK] = v;
597 				intflags |= 1;
598 			}
599 			b->cs_rbput = i;
600 		}
601 	    }
602 	} while(intflags & 4);
603 #undef b
604 
605 	if(intflags & 1) {
606 		if(BASEPRI(sr)) {
607 			spl1();
608 			zsshortcuts++;
609 			return(zssoft(sr));
610 		}
611 		else if(!cb_scheduled) {
612 			cb_scheduled++;
613 			add_sicallback((si_farg)zssoft, 0, 0);
614 		}
615 	}
616 	return(intflags & 2);
617 }
618 
619 static int
620 zsrint(cs, zc)
621 register struct zs_chanstate	*cs;
622 register volatile struct zschan	*zc;
623 {
624 	register int c;
625 
626 	/*
627 	 * First read the status, because read of the received char
628 	 * destroy the status of this char.
629 	 */
630 	c = ZS_READ(zc, 1);
631 	c |= (zc->zc_data << 8);
632 
633 	/* clear receive error & interrupt condition */
634 	zc->zc_csr = ZSWR0_RESET_ERRORS;
635 	zc->zc_csr = ZSWR0_CLR_INTR;
636 
637 	return(ZRING_MAKE(ZRING_RINT, c));
638 }
639 
640 static int
641 zsxint(cs, zc)
642 register struct zs_chanstate	*cs;
643 register volatile struct zschan	*zc;
644 {
645 	register int i = cs->cs_tbc;
646 
647 	if(i == 0) {
648 		zc->zc_csr = ZSWR0_RESET_TXINT;
649 		zc->zc_csr = ZSWR0_CLR_INTR;
650 		return(ZRING_MAKE(ZRING_XINT, 0));
651 	}
652 	cs->cs_tbc = i - 1;
653 	zc->zc_data = *cs->cs_tba++;
654 	zc->zc_csr = ZSWR0_CLR_INTR;
655 	return (0);
656 }
657 
658 static int
659 zssint(cs, zc)
660 register struct zs_chanstate	*cs;
661 register volatile struct zschan	*zc;
662 {
663 	register int rr0;
664 
665 	rr0 = zc->zc_csr;
666 	zc->zc_csr = ZSWR0_RESET_STATUS;
667 	zc->zc_csr = ZSWR0_CLR_INTR;
668 	/*
669 	 * The chip's hardware flow control is, as noted in zsreg.h,
670 	 * busted---if the DCD line goes low the chip shuts off the
671 	 * receiver (!).  If we want hardware CTS flow control but do
672 	 * not have it, and carrier is now on, turn HFC on; if we have
673 	 * HFC now but carrier has gone low, turn it off.
674 	 */
675 	if(rr0 & ZSRR0_DCD) {
676 		if(cs->cs_ttyp->t_cflag & CCTS_OFLOW &&
677 		    (cs->cs_creg[3] & ZSWR3_HFC) == 0) {
678 			cs->cs_creg[3] |= ZSWR3_HFC;
679 			ZS_WRITE(zc, 3, cs->cs_creg[3]);
680 		}
681 	}
682 	else {
683 		if (cs->cs_creg[3] & ZSWR3_HFC) {
684 			cs->cs_creg[3] &= ~ZSWR3_HFC;
685 			ZS_WRITE(zc, 3, cs->cs_creg[3]);
686 		}
687 	}
688 	return(ZRING_MAKE(ZRING_SINT, rr0));
689 }
690 
691 /*
692  * Print out a ring or fifo overrun error message.
693  */
694 static void
695 zsoverrun(unit, ptime, what)
696 int	unit;
697 long	*ptime;
698 char	*what;
699 {
700 
701 	if(*ptime != time.tv_sec) {
702 		*ptime = time.tv_sec;
703 		log(LOG_WARNING, "zs%d%c: %s overrun\n", unit >> 1,
704 		    (unit & 1) + 'a', what);
705 	}
706 }
707 
708 /*
709  * ZS software interrupt.  Scan all channels for deferred interrupts.
710  */
711 int
712 zssoft(sr)
713 long sr;
714 {
715     register struct zs_chanstate	*cs;
716     register volatile struct zschan	*zc;
717     register struct linesw		*line;
718     register struct tty			*tp;
719     register int			get, n, c, cc, unit, s;
720  	     int			retval = 0;
721 
722     cb_scheduled = 0;
723     s = spltty();
724     for(cs = zslist; cs != NULL; cs = cs->cs_next) {
725 	get = cs->cs_rbget;
726 again:
727 	n = cs->cs_rbput;	/* atomic			*/
728 	if(get == n)		/* nothing more on this line	*/
729 		continue;
730 	retval = 1;
731 	unit   = cs->cs_unit;	/* set up to handle interrupts	*/
732 	zc     = cs->cs_zc;
733 	tp     = cs->cs_ttyp;
734 	line   = tp->t_linesw;
735 	/*
736 	 * Compute the number of interrupts in the receive ring.
737 	 * If the count is overlarge, we lost some events, and
738 	 * must advance to the first valid one.  It may get
739 	 * overwritten if more data are arriving, but this is
740 	 * too expensive to check and gains nothing (we already
741 	 * lost out; all we can do at this point is trade one
742 	 * kind of loss for another).
743 	 */
744 	n -= get;
745 	if(n > ZLRB_RING_SIZE) {
746 		zsoverrun(unit, &cs->cs_rotime, "ring");
747 		get += n - ZLRB_RING_SIZE;
748 		n    = ZLRB_RING_SIZE;
749 	}
750 	while(--n >= 0) {
751 		/* race to keep ahead of incoming interrupts */
752 		c = cs->cs_rbuf[get++ & ZLRB_RING_MASK];
753 		switch (ZRING_TYPE(c)) {
754 
755 		case ZRING_RINT:
756 			c = ZRING_VALUE(c);
757 			if(c & ZSRR1_DO)
758 				zsoverrun(unit, &cs->cs_fotime, "fifo");
759 			cc = c >> 8;
760 			if(c & ZSRR1_FE)
761 				cc |= TTY_FE;
762 			if(c & ZSRR1_PE)
763 				cc |= TTY_PE;
764 			line->l_rint(cc, tp);
765 			break;
766 
767 		case ZRING_XINT:
768 			/*
769 			 * Transmit done: change registers and resume,
770 			 * or clear BUSY.
771 			 */
772 			if(cs->cs_heldchange) {
773 				int sps;
774 
775 				sps = splzs();
776 				c = zc->zc_csr;
777 				if((c & ZSRR0_DCD) == 0)
778 					cs->cs_preg[3] &= ~ZSWR3_HFC;
779 				bcopy((caddr_t)cs->cs_preg,
780 				    (caddr_t)cs->cs_creg, 16);
781 				zs_loadchannelregs(zc, cs->cs_creg);
782 				splx(sps);
783 				cs->cs_heldchange = 0;
784 				if(cs->cs_heldtbc
785 					&& (tp->t_state & TS_TTSTOP) == 0) {
786 					cs->cs_tbc = cs->cs_heldtbc - 1;
787 					zc->zc_data = *cs->cs_tba++;
788 					goto again;
789 				}
790 			}
791 			tp->t_state &= ~TS_BUSY;
792 			if(tp->t_state & TS_FLUSH)
793 				tp->t_state &= ~TS_FLUSH;
794 			else ndflush(&tp->t_outq,cs->cs_tba
795 						- (caddr_t)tp->t_outq.c_cf);
796 			line->l_start(tp);
797 			break;
798 
799 		case ZRING_SINT:
800 			/*
801 			 * Status line change.  HFC bit is run in
802 			 * hardware interrupt, to avoid locking
803 			 * at splzs here.
804 			 */
805 			c = ZRING_VALUE(c);
806 			if((c ^ cs->cs_rr0) & ZSRR0_DCD) {
807 				cc = (c & ZSRR0_DCD) != 0;
808 				if(line->l_modem(tp, cc) == 0)
809 					zs_modem(cs, ZSWR5_RTS|ZSWR5_DTR,
810 							cc ? DMBIS : DMBIC);
811 			}
812 			cs->cs_rr0 = c;
813 			break;
814 
815 		default:
816 			log(LOG_ERR, "zs%d%c: bad ZRING_TYPE (%x)\n",
817 			    unit >> 1, (unit & 1) + 'a', c);
818 			break;
819 		}
820 	}
821 	cs->cs_rbget = get;
822 	goto again;
823     }
824     splx(s);
825     return (retval);
826 }
827 
828 int
829 zsioctl(dev, cmd, data, flag, p)
830 dev_t		dev;
831 u_long		cmd;
832 caddr_t		data;
833 int		flag;
834 struct proc	*p;
835 {
836 		 int			unit = ZS_UNIT(dev);
837 		 struct zs_softc	*zi = zs_cd.cd_devs[unit >> 1];
838 	register struct tty		*tp = zi->zi_cs[unit & 1].cs_ttyp;
839 	register int			error, s;
840 	register struct zs_chanstate	*cs = &zi->zi_cs[unit & 1];
841 
842 	error = tp->t_linesw->l_ioctl(tp, cmd, data, flag, p);
843 	if(error != EPASSTHROUGH)
844 		return(error);
845 
846 	error = ttioctl(tp, cmd, data, flag, p);
847 	if(error !=EPASSTHROUGH)
848 		return (error);
849 
850 	switch (cmd) {
851 	case TIOCSBRK:
852 		s = splzs();
853 		cs->cs_preg[5] |= ZSWR5_BREAK;
854 		cs->cs_creg[5] |= ZSWR5_BREAK;
855 		ZS_WRITE(cs->cs_zc, 5, cs->cs_creg[5]);
856 		splx(s);
857 		break;
858 	case TIOCCBRK:
859 		s = splzs();
860 		cs->cs_preg[5] &= ~ZSWR5_BREAK;
861 		cs->cs_creg[5] &= ~ZSWR5_BREAK;
862 		ZS_WRITE(cs->cs_zc, 5, cs->cs_creg[5]);
863 		splx(s);
864 		break;
865 	case TIOCGFLAGS: {
866 		int bits = 0;
867 
868 		if(cs->cs_softcar)
869 			bits |= TIOCFLAG_SOFTCAR;
870 		if(cs->cs_creg[15] & ZSWR15_DCD_IE)
871 			bits |= TIOCFLAG_CLOCAL;
872 		if(cs->cs_creg[3] & ZSWR3_HFC)
873 			bits |= TIOCFLAG_CRTSCTS;
874 		*(int *)data = bits;
875 		break;
876 	}
877 	case TIOCSFLAGS: {
878 		int userbits = 0;
879 
880 		error = suser(p->p_ucred, &p->p_acflag);
881 		if(error != 0)
882 			return (EPERM);
883 
884 		userbits = *(int *)data;
885 
886 		/*
887 		 * can have `local' or `softcar', and `rtscts' or `mdmbuf'
888 		 # defaulting to software flow control.
889 		 */
890 		if(userbits & TIOCFLAG_SOFTCAR && userbits & TIOCFLAG_CLOCAL)
891 			return(EINVAL);
892 		if(userbits & TIOCFLAG_MDMBUF)	/* don't support this (yet?) */
893 			return(ENODEV);
894 
895 		s = splzs();
896 		if((userbits & TIOCFLAG_SOFTCAR)) {
897 			cs->cs_softcar = 1;	/* turn on softcar */
898 			cs->cs_preg[15] &= ~ZSWR15_DCD_IE; /* turn off dcd */
899 			cs->cs_creg[15] &= ~ZSWR15_DCD_IE;
900 			ZS_WRITE(cs->cs_zc, 15, cs->cs_creg[15]);
901 		}
902 		else if(userbits & TIOCFLAG_CLOCAL) {
903 			cs->cs_softcar = 0; 	/* turn off softcar */
904 			cs->cs_preg[15] |= ZSWR15_DCD_IE; /* turn on dcd */
905 			cs->cs_creg[15] |= ZSWR15_DCD_IE;
906 			ZS_WRITE(cs->cs_zc, 15, cs->cs_creg[15]);
907 			tp->t_termios.c_cflag |= CLOCAL;
908 		}
909 		if(userbits & TIOCFLAG_CRTSCTS) {
910 			cs->cs_preg[15] |= ZSWR15_CTS_IE;
911 			cs->cs_creg[15] |= ZSWR15_CTS_IE;
912 			ZS_WRITE(cs->cs_zc, 15, cs->cs_creg[15]);
913 			cs->cs_preg[3] |= ZSWR3_HFC;
914 			cs->cs_creg[3] |= ZSWR3_HFC;
915 			ZS_WRITE(cs->cs_zc, 3, cs->cs_creg[3]);
916 			tp->t_termios.c_cflag |= CRTSCTS;
917 		}
918 		else {
919 			/* no mdmbuf, so we must want software flow control */
920 			cs->cs_preg[15] &= ~ZSWR15_CTS_IE;
921 			cs->cs_creg[15] &= ~ZSWR15_CTS_IE;
922 			ZS_WRITE(cs->cs_zc, 15, cs->cs_creg[15]);
923 			cs->cs_preg[3] &= ~ZSWR3_HFC;
924 			cs->cs_creg[3] &= ~ZSWR3_HFC;
925 			ZS_WRITE(cs->cs_zc, 3, cs->cs_creg[3]);
926 			tp->t_termios.c_cflag &= ~CRTSCTS;
927 		}
928 		splx(s);
929 		break;
930 	}
931 	case TIOCSDTR:
932 		zs_modem(cs, ZSWR5_DTR, DMBIS);
933 		break;
934 	case TIOCCDTR:
935 		zs_modem(cs, ZSWR5_DTR, DMBIC);
936 		break;
937 	case TIOCMGET:
938 		zs_modem(cs, 0, DMGET);
939 		break;
940 	case TIOCMSET:
941 	case TIOCMBIS:
942 	case TIOCMBIC:
943 	default:
944 		return (EPASSTHROUGH);
945 	}
946 	return (0);
947 }
948 
949 /*
950  * Start or restart transmission.
951  */
952 static void
953 zsstart(tp)
954 register struct tty *tp;
955 {
956 	register struct zs_chanstate	*cs;
957 	register int			s, nch;
958 		 int			unit = ZS_UNIT(tp->t_dev);
959 		 struct zs_softc	*zi = zs_cd.cd_devs[unit >> 1];
960 
961 	cs = &zi->zi_cs[unit & 1];
962 	s  = spltty();
963 
964 	/*
965 	 * If currently active or delaying, no need to do anything.
966 	 */
967 	if(tp->t_state & (TS_TIMEOUT | TS_BUSY | TS_TTSTOP))
968 		goto out;
969 
970 	/*
971 	 * If there are sleepers, and output has drained below low
972 	 * water mark, awaken.
973 	 */
974 	if(tp->t_outq.c_cc <= tp->t_lowat) {
975 		if(tp->t_state & TS_ASLEEP) {
976 			tp->t_state &= ~TS_ASLEEP;
977 			wakeup((caddr_t)&tp->t_outq);
978 		}
979 		selwakeup(&tp->t_wsel);
980 	}
981 
982 	nch = ndqb(&tp->t_outq, 0);	/* XXX */
983 	if(nch) {
984 		register char *p = tp->t_outq.c_cf;
985 
986 		/* mark busy, enable tx done interrupts, & send first byte */
987 		tp->t_state |= TS_BUSY;
988 		(void) splzs();
989 		cs->cs_preg[1] |= ZSWR1_TIE;
990 		cs->cs_creg[1] |= ZSWR1_TIE;
991 		ZS_WRITE(cs->cs_zc, 1, cs->cs_creg[1]);
992 		cs->cs_zc->zc_data = *p;
993 		cs->cs_tba = p + 1;
994 		cs->cs_tbc = nch - 1;
995 	} else {
996 		/*
997 		 * Nothing to send, turn off transmit done interrupts.
998 		 * This is useful if something is doing polled output.
999 		 */
1000 		(void) splzs();
1001 		cs->cs_preg[1] &= ~ZSWR1_TIE;
1002 		cs->cs_creg[1] &= ~ZSWR1_TIE;
1003 		ZS_WRITE(cs->cs_zc, 1, cs->cs_creg[1]);
1004 	}
1005 out:
1006 	splx(s);
1007 }
1008 
1009 /*
1010  * Stop output, e.g., for ^S or output flush.
1011  */
1012 void
1013 zsstop(tp, flag)
1014 register struct tty	*tp;
1015 	 int		flag;
1016 {
1017 	register struct zs_chanstate	*cs;
1018 	register int			s, unit = ZS_UNIT(tp->t_dev);
1019 		 struct zs_softc	*zi = zs_cd.cd_devs[unit >> 1];
1020 
1021 	cs = &zi->zi_cs[unit & 1];
1022 	s  = splzs();
1023 	if(tp->t_state & TS_BUSY) {
1024 		/*
1025 		 * Device is transmitting; must stop it.
1026 		 */
1027 		cs->cs_tbc = 0;
1028 		if ((tp->t_state & TS_TTSTOP) == 0)
1029 			tp->t_state |= TS_FLUSH;
1030 	}
1031 	splx(s);
1032 }
1033 
1034 static void
1035 zs_shutdown(cs)
1036 	struct zs_chanstate	*cs;
1037 {
1038 	struct tty	*tp = cs->cs_ttyp;
1039 	int		s;
1040 
1041 	s = splzs();
1042 
1043 	/*
1044 	 * Hang up if necessary.  Wait a bit, so the other side has time to
1045 	 * notice even if we immediately open the port again.
1046 	 */
1047 	if(tp->t_cflag & HUPCL) {
1048 		zs_modem(cs, 0, DMSET);
1049 		(void)tsleep((caddr_t)cs, TTIPRI, ttclos, hz);
1050 	}
1051 
1052 	/* Clear any break condition set with TIOCSBRK. */
1053 	if(cs->cs_creg[5] & ZSWR5_BREAK) {
1054 		cs->cs_preg[5] &= ~ZSWR5_BREAK;
1055 		cs->cs_creg[5] &= ~ZSWR5_BREAK;
1056 		ZS_WRITE(cs->cs_zc, 5, cs->cs_creg[5]);
1057 	}
1058 
1059 	/*
1060 	 * Drop all lines and cancel interrupts
1061 	 */
1062 	zs_loadchannelregs(cs->cs_zc, zs_init_regs);
1063 	splx(s);
1064 }
1065 
1066 /*
1067  * Set ZS tty parameters from termios.
1068  *
1069  * This routine makes use of the fact that only registers
1070  * 1, 3, 4, 5, 9, 10, 11, 12, 13, 14, and 15 are written.
1071  */
1072 static int
1073 zsparam(tp, t)
1074 register struct tty	*tp;
1075 register struct termios	*t;
1076 {
1077 		 int			unit = ZS_UNIT(tp->t_dev);
1078 		 struct zs_softc	*zi = zs_cd.cd_devs[unit >> 1];
1079 	register struct zs_chanstate	*cs = &zi->zi_cs[unit & 1];
1080 		 int			cdiv, clkm, brgm, tcon;
1081 	register int			tmp, tmp5, cflag, s;
1082 
1083 	tmp  = t->c_ospeed;
1084 	tmp5 = t->c_ispeed;
1085 	if(tmp < 0 || (tmp5 && tmp5 != tmp))
1086 		return(EINVAL);
1087 	if(tmp == 0) {
1088 		/* stty 0 => drop DTR and RTS */
1089 		zs_modem(cs, 0, DMSET);
1090 		return(0);
1091 	}
1092 	tmp = zsbaudrate(unit, tmp, &cdiv, &clkm, &brgm, &tcon);
1093 	if (tmp < 0)
1094 		return(EINVAL);
1095 	tp->t_ispeed = tp->t_ospeed = tmp;
1096 
1097 	cflag = tp->t_cflag = t->c_cflag;
1098 	if (cflag & CSTOPB)
1099 		cdiv |= ZSWR4_TWOSB;
1100 	else
1101 		cdiv |= ZSWR4_ONESB;
1102 	if (!(cflag & PARODD))
1103 		cdiv |= ZSWR4_EVENP;
1104 	if (cflag & PARENB)
1105 		cdiv |= ZSWR4_PARENB;
1106 
1107 	switch(cflag & CSIZE) {
1108 	case CS5:
1109 		tmp  = ZSWR3_RX_5;
1110 		tmp5 = ZSWR5_TX_5;
1111 		break;
1112 	case CS6:
1113 		tmp  = ZSWR3_RX_6;
1114 		tmp5 = ZSWR5_TX_6;
1115 		break;
1116 	case CS7:
1117 		tmp  = ZSWR3_RX_7;
1118 		tmp5 = ZSWR5_TX_7;
1119 		break;
1120 	case CS8:
1121 	default:
1122 		tmp  = ZSWR3_RX_8;
1123 		tmp5 = ZSWR5_TX_8;
1124 		break;
1125 	}
1126 	tmp  |= ZSWR3_RX_ENABLE;
1127 	tmp5 |= ZSWR5_TX_ENABLE | ZSWR5_DTR | ZSWR5_RTS;
1128 
1129 	/*
1130 	 * Block interrupts so that state will not
1131 	 * be altered until we are done setting it up.
1132 	 */
1133 	s = splzs();
1134 	cs->cs_preg[4]  = cdiv;
1135 	cs->cs_preg[11] = clkm;
1136 	cs->cs_preg[12] = tcon;
1137 	cs->cs_preg[13] = tcon >> 8;
1138 	cs->cs_preg[14] = brgm;
1139 	cs->cs_preg[1]  = ZSWR1_RIE | ZSWR1_TIE | ZSWR1_SIE;
1140 	cs->cs_preg[9]  = ZSWR9_MASTER_IE | ZSWR9_VECTOR_INCL_STAT;
1141 	cs->cs_preg[10] = ZSWR10_NRZ;
1142 	cs->cs_preg[15] = ZSWR15_BREAK_IE | ZSWR15_DCD_IE;
1143 
1144 	/*
1145 	 * Output hardware flow control on the chip is horrendous: if
1146 	 * carrier detect drops, the receiver is disabled.  Hence we
1147 	 * can only do this when the carrier is on.
1148 	 */
1149 	if(cflag & CCTS_OFLOW && cs->cs_zc->zc_csr & ZSRR0_DCD)
1150 		tmp |= ZSWR3_HFC;
1151 	cs->cs_preg[3] = tmp;
1152 	cs->cs_preg[5] = tmp5;
1153 
1154 	/*
1155 	 * If nothing is being transmitted, set up new current values,
1156 	 * else mark them as pending.
1157 	 */
1158 	if(cs->cs_heldchange == 0) {
1159 		if (cs->cs_ttyp->t_state & TS_BUSY) {
1160 			cs->cs_heldtbc = cs->cs_tbc;
1161 			cs->cs_tbc = 0;
1162 			cs->cs_heldchange = 1;
1163 		} else {
1164 			bcopy((caddr_t)cs->cs_preg, (caddr_t)cs->cs_creg, 16);
1165 			zs_loadchannelregs(cs->cs_zc, cs->cs_creg);
1166 		}
1167 	}
1168 	splx(s);
1169 	return (0);
1170 }
1171 
1172 /*
1173  * search for the best matching baudrate
1174  */
1175 static int
1176 zsbaudrate(unit, wanted, divisor, clockmode, brgenmode, timeconst)
1177 int	unit, wanted, *divisor, *clockmode, *brgenmode, *timeconst;
1178 {
1179 	int	bestdiff, bestbps, source;
1180 
1181 	bestdiff = bestbps = 0;
1182 	unit = (unit & 1) << 2;
1183 	for (source = 0; source < 4; ++source) {
1184 		long	freq = zs_frequencies[unit + source];
1185 		int	diff, bps, div, clkm, brgm, tcon;
1186 
1187 		bps = div = clkm = brgm = tcon = 0;
1188 		switch (source) {
1189 			case 0:	/* BRgen, PCLK */
1190 				brgm = ZSWR14_BAUD_ENA|ZSWR14_BAUD_FROM_PCLK;
1191 				break;
1192 			case 1:	/* BRgen, RTxC */
1193 				brgm = ZSWR14_BAUD_ENA;
1194 				break;
1195 			case 2: /* RTxC */
1196 				clkm = ZSWR11_RXCLK_RTXC|ZSWR11_TXCLK_RTXC;
1197 				break;
1198 			case 3: /* TRxC */
1199 				clkm = ZSWR11_RXCLK_TRXC|ZSWR11_TXCLK_TRXC;
1200 				break;
1201 		}
1202 		switch (source) {
1203 			case 0:
1204 			case 1:
1205 				div  = ZSWR4_CLK_X16;
1206 				clkm = ZSWR11_RXCLK_BAUD|ZSWR11_TXCLK_BAUD;
1207 				tcon = BPS_TO_TCONST(freq, wanted);
1208 				if (tcon < 0)
1209 					tcon = 0;
1210 				bps  = TCONST_TO_BPS(freq, tcon);
1211 				break;
1212 			case 2:
1213 			case 3:
1214 			{	int	b1 = freq / 16, d1 = abs(b1 - wanted);
1215 				int	b2 = freq / 32, d2 = abs(b2 - wanted);
1216 				int	b3 = freq / 64, d3 = abs(b3 - wanted);
1217 
1218 				if (d1 < d2 && d1 < d3) {
1219 					div = ZSWR4_CLK_X16;
1220 					bps = b1;
1221 				} else if (d2 < d3 && d2 < d1) {
1222 					div = ZSWR4_CLK_X32;
1223 					bps = b2;
1224 				} else {
1225 					div = ZSWR4_CLK_X64;
1226 					bps = b3;
1227 				}
1228 				brgm = tcon = 0;
1229 				break;
1230 			}
1231 		}
1232 		diff = abs(bps - wanted);
1233 		if (!source || diff < bestdiff) {
1234 			*divisor   = div;
1235 			*clockmode = clkm;
1236 			*brgenmode = brgm;
1237 			*timeconst = tcon;
1238 			bestbps    = bps;
1239 			bestdiff   = diff;
1240 			if (diff == 0)
1241 				break;
1242 		}
1243 	}
1244 	/* Allow deviations upto 5% */
1245 	if (20 * bestdiff > wanted)
1246 		return -1;
1247 	return bestbps;
1248 }
1249 
1250 /*
1251  * Raise or lower modem control (DTR/RTS) signals.  If a character is
1252  * in transmission, the change is deferred.
1253  */
1254 static int
1255 zs_modem(cs, bits, how)
1256 struct zs_chanstate	*cs;
1257 int			bits, how;
1258 {
1259 	int s, mbits;
1260 
1261 	bits  &= ZSWR5_DTR | ZSWR5_RTS;
1262 
1263 	s = splzs();
1264 	mbits  = cs->cs_preg[5] &  (ZSWR5_DTR | ZSWR5_RTS);
1265 
1266 	switch(how) {
1267 		case DMSET:
1268 				mbits  = bits;
1269 				break;
1270 		case DMBIS:
1271 				mbits |= bits;
1272 				break;
1273 		case DMBIC:
1274 				mbits &= ~bits;
1275 				break;
1276 		case DMGET:
1277 				splx(s);
1278 				return(mbits);
1279 	}
1280 
1281 	cs->cs_preg[5] = (cs->cs_preg[5] & ~(ZSWR5_DTR | ZSWR5_RTS)) | mbits;
1282 	if(cs->cs_heldchange == 0) {
1283 		if(cs->cs_ttyp->t_state & TS_BUSY) {
1284 			cs->cs_heldtbc = cs->cs_tbc;
1285 			cs->cs_tbc = 0;
1286 			cs->cs_heldchange = 1;
1287 		}
1288 		else {
1289 			ZS_WRITE(cs->cs_zc, 5, cs->cs_creg[5]);
1290 		}
1291 	}
1292 	splx(s);
1293 	return(0);
1294 }
1295 
1296 /*
1297  * Write the given register set to the given zs channel in the proper order.
1298  * The channel must not be transmitting at the time.  The receiver will
1299  * be disabled for the time it takes to write all the registers.
1300  */
1301 static void
1302 zs_loadchannelregs(zc, reg)
1303 volatile struct zschan	*zc;
1304 u_char			*reg;
1305 {
1306 	int i;
1307 
1308 	zc->zc_csr = ZSM_RESET_ERR;	/* reset error condition */
1309 	i = zc->zc_data;		/* drain fifo */
1310 	i = zc->zc_data;
1311 	i = zc->zc_data;
1312 	ZS_WRITE(zc,  4, reg[4]);
1313 	ZS_WRITE(zc, 10, reg[10]);
1314 	ZS_WRITE(zc,  3, reg[3] & ~ZSWR3_RX_ENABLE);
1315 	ZS_WRITE(zc,  5, reg[5] & ~ZSWR5_TX_ENABLE);
1316 	ZS_WRITE(zc,  1, reg[1]);
1317 	ZS_WRITE(zc,  9, reg[9]);
1318 	ZS_WRITE(zc, 11, reg[11]);
1319 	ZS_WRITE(zc, 12, reg[12]);
1320 	ZS_WRITE(zc, 13, reg[13]);
1321 	ZS_WRITE(zc, 14, reg[14]);
1322 	ZS_WRITE(zc, 15, reg[15]);
1323 	ZS_WRITE(zc,  3, reg[3]);
1324 	ZS_WRITE(zc,  5, reg[5]);
1325 }
1326 #endif /* NZS > 1 */
1327