xref: /netbsd-src/sys/arch/atari/dev/zs.c (revision 23c8222edbfb0f0932d88a8351d3a0cf817dfb9e)
1 /*	$NetBSD: zs.c,v 1.42 2004/03/25 10:17:19 leo Exp $	*/
2 
3 /*
4  * Copyright (c) 1992, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * This software was developed by the Computer Systems Engineering group
8  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
9  * contributed to Berkeley.
10  *
11  *
12  * All advertising materials mentioning features or use of this software
13  * must display the following acknowledgement:
14  *	This product includes software developed by the University of
15  *	California, Lawrence Berkeley Laboratory.
16  *
17  * Redistribution and use in source and binary forms, with or without
18  * modification, are permitted provided that the following conditions
19  * are met:
20  * 1. Redistributions of source code must retain the above copyright
21  *    notice, this list of conditions and the following disclaimer.
22  * 2. Redistributions in binary form must reproduce the above copyright
23  *    notice, this list of conditions and the following disclaimer in the
24  *    documentation and/or other materials provided with the distribution.
25  * 3. Neither the name of the University nor the names of its contributors
26  *    may be used to endorse or promote products derived from this software
27  *    without specific prior written permission.
28  *
29  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
30  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
31  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
32  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
33  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
34  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
35  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
36  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
37  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
38  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
39  * SUCH DAMAGE.
40  *
41  *	@(#)zs.c	8.1 (Berkeley) 7/19/93
42  */
43 
44 /*-
45  * Copyright (c) 1995 The NetBSD Foundation, Inc. (Atari modifications)
46  * All rights reserved.
47  *
48  * This code is derived from software contributed to The NetBSD Foundation
49  * by Leo Weppelman.
50  *
51  * Redistribution and use in source and binary forms, with or without
52  * modification, are permitted provided that the following conditions
53  * are met:
54  * 1. Redistributions of source code must retain the above copyright
55  *    notice, this list of conditions and the following disclaimer.
56  * 2. Redistributions in binary form must reproduce the above copyright
57  *    notice, this list of conditions and the following disclaimer in the
58  *    documentation and/or other materials provided with the distribution.
59  * 3. Neither the name of The NetBSD Foundation nor the names of its
60  *    contributors may be used to endorse or promote products derived
61  *    from this software without specific prior written permission.
62  *
63  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
64  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
65  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
66  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
67  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
68  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
69  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
70  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
71  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
72  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
73  * POSSIBILITY OF SUCH DAMAGE.
74  */
75 
76 /*
77  * Zilog Z8530 (ZSCC) driver.
78  *
79  * Runs two tty ports (modem2 and serial2) on zs0.
80  *
81  * This driver knows far too much about chip to usage mappings.
82  */
83 
84 #include <sys/cdefs.h>
85 __KERNEL_RCSID(0, "$NetBSD: zs.c,v 1.42 2004/03/25 10:17:19 leo Exp $");
86 
87 #include <sys/param.h>
88 #include <sys/systm.h>
89 #include <sys/proc.h>
90 #include <sys/device.h>
91 #include <sys/conf.h>
92 #include <sys/file.h>
93 #include <sys/ioctl.h>
94 #include <sys/malloc.h>
95 #include <sys/tty.h>
96 #include <sys/time.h>
97 #include <sys/kernel.h>
98 #include <sys/syslog.h>
99 
100 #include <machine/cpu.h>
101 #include <machine/iomap.h>
102 #include <machine/scu.h>
103 #include <machine/mfp.h>
104 #include <atari/dev/ym2149reg.h>
105 
106 #include <dev/ic/z8530reg.h>
107 #include <atari/dev/zsvar.h>
108 #include "zs.h"
109 #if NZS > 1
110 #error "This driver supports only 1 85C30!"
111 #endif
112 
113 #if NZS > 0
114 
115 #define PCLK	(8053976)	/* PCLK pin input clock rate */
116 #define PCLK_HD	(9600 * 1536)	/* PCLK on Hades pin input clock rate */
117 
118 #define splzs	spl5
119 
120 /*
121  * Software state per found chip.
122  */
123 struct zs_softc {
124     struct	device		zi_dev;    /* base device		  */
125     volatile struct zsdevice	*zi_zs;    /* chip registers		  */
126     struct	zs_chanstate	zi_cs[2];  /* chan A and B software state */
127 };
128 
129 static u_char	cb_scheduled = 0;	/* Already asked for callback? */
130 /*
131  * Define the registers for a closed port
132  */
133 static u_char zs_init_regs[16] = {
134 /*  0 */	0,
135 /*  1 */	0,
136 /*  2 */	0x60,
137 /*  3 */	0,
138 /*  4 */	0,
139 /*  5 */	0,
140 /*  6 */	0,
141 /*  7 */	0,
142 /*  8 */	0,
143 /*  9 */	ZSWR9_MASTER_IE | ZSWR9_VECTOR_INCL_STAT,
144 /* 10 */	ZSWR10_NRZ,
145 /* 11 */	ZSWR11_TXCLK_BAUD | ZSWR11_RXCLK_BAUD,
146 /* 12 */	0,
147 /* 13 */	0,
148 /* 14 */	ZSWR14_BAUD_FROM_PCLK | ZSWR14_BAUD_ENA,
149 /* 15 */	0
150 };
151 
152 /*
153  * Define the machine dependant clock frequencies
154  * If BRgen feeds sender/receiver we always use a
155  * divisor 16, therefor the division by 16 can as
156  * well be done here.
157  */
158 static u_long zs_freqs_tt[] = {
159 	/*
160 	 * Atari TT, RTxCB is generated by TT-MFP timer C,
161 	 * which is set to 307.2KHz during initialisation
162 	 * and never changed afterwards.
163 	 */
164 	PCLK/16,	/* BRgen, PCLK,  divisor 16	*/
165 	 229500,	/* BRgen, RTxCA, divisor 16	*/
166 	3672000,	/* RTxCA, from PCLK4		*/
167 	      0,	/* TRxCA, external		*/
168 
169 	PCLK/16,	/* BRgen, PCLK,  divisor 16	*/
170 	  19200,	/* BRgen, RTxCB, divisor 16	*/
171 	 307200,	/* RTxCB, from TT-MFP TCO	*/
172 	2457600		/* TRxCB, from BCLK		*/
173 };
174 
175 static u_long zs_freqs_falcon[] = {
176 	/*
177 	 * Atari Falcon, XXX no specs available, this might be wrong
178 	 */
179 	PCLK/16,	/* BRgen, PCLK,  divisor 16	*/
180 	 229500,	/* BRgen, RTxCA, divisor 16	*/
181 	3672000,	/* RTxCA, ???			*/
182 	      0,	/* TRxCA, external		*/
183 
184 	PCLK/16,	/* BRgen, PCLK,  divisor 16	*/
185 	 229500,	/* BRgen, RTxCB, divisor 16	*/
186 	3672000,	/* RTxCB, ???			*/
187 	2457600		/* TRxCB, ???			*/
188 };
189 
190 static u_long zs_freqs_hades[] = {
191 	/*
192 	 * XXX: Channel-A unchecked!!!!!
193 	 */
194      PCLK_HD/16,	/* BRgen, PCLK,  divisor 16	*/
195 	 229500,	/* BRgen, RTxCA, divisor 16	*/
196 	3672000,	/* RTxCA, from PCLK4		*/
197 	      0,	/* TRxCA, external		*/
198 
199      PCLK_HD/16,	/* BRgen, PCLK,  divisor 16	*/
200 	 235550,	/* BRgen, RTxCB, divisor 16	*/
201 	3768800,	/* RTxCB, 3.7688MHz		*/
202 	3768800		/* TRxCB, 3.7688MHz		*/
203 };
204 
205 static u_long zs_freqs_generic[] = {
206 	/*
207 	 * other machines, assume only PCLK is available
208 	 */
209 	PCLK/16,	/* BRgen, PCLK,  divisor 16	*/
210 	      0,	/* BRgen, RTxCA, divisor 16	*/
211 	      0,	/* RTxCA, unknown		*/
212 	      0,	/* TRxCA, unknown		*/
213 
214 	PCLK/16,	/* BRgen, PCLK,  divisor 16	*/
215 	      0,	/* BRgen, RTxCB, divisor 16	*/
216 	      0,	/* RTxCB, unknown		*/
217 	      0		/* TRxCB, unknown		*/
218 };
219 static u_long *zs_frequencies;
220 
221 /* Definition of the driver for autoconfig. */
222 static int	zsmatch __P((struct device *, struct cfdata *, void *));
223 static void	zsattach __P((struct device *, struct device *, void *));
224 
225 CFATTACH_DECL(zs, sizeof(struct zs_softc),
226     zsmatch, zsattach, NULL, NULL);
227 
228 extern struct cfdriver zs_cd;
229 
230 /* {b,c}devsw[] function prototypes */
231 dev_type_open(zsopen);
232 dev_type_close(zsclose);
233 dev_type_read(zsread);
234 dev_type_write(zswrite);
235 dev_type_ioctl(zsioctl);
236 dev_type_stop(zsstop);
237 dev_type_tty(zstty);
238 dev_type_poll(zspoll);
239 
240 const struct cdevsw zs_cdevsw = {
241 	zsopen, zsclose, zsread, zswrite, zsioctl,
242 	zsstop, zstty, zspoll, nommap, ttykqfilter, D_TTY
243 };
244 
245 /* Interrupt handlers. */
246 int		zshard __P((long));
247 static int	zssoft __P((long));
248 static int	zsrint __P((struct zs_chanstate *, volatile struct zschan *));
249 static int	zsxint __P((struct zs_chanstate *, volatile struct zschan *));
250 static int	zssint __P((struct zs_chanstate *, volatile struct zschan *));
251 
252 static struct zs_chanstate *zslist;
253 
254 /* Routines called from other code. */
255 static void	zsstart __P((struct tty *));
256 
257 /* Routines purely local to this driver. */
258 static void	zsoverrun __P((int, long *, char *));
259 static int	zsparam __P((struct tty *, struct termios *));
260 static int	zsbaudrate __P((int, int, int *, int *, int *, int *));
261 static int	zs_modem __P((struct zs_chanstate *, int, int));
262 static void	zs_loadchannelregs __P((volatile struct zschan *, u_char *));
263 static void	zs_shutdown __P((struct zs_chanstate *));
264 
265 static int zsshortcuts;	/* number of "shortcut" software interrupts */
266 
267 static int
268 zsmatch(pdp, cfp, auxp)
269 struct device	*pdp;
270 struct cfdata	*cfp;
271 void		*auxp;
272 {
273 	static int	zs_matched = 0;
274 
275 	if(strcmp("zs", auxp) || zs_matched)
276 		return(0);
277 	zs_matched = 1;
278 	return(1);
279 }
280 
281 /*
282  * Attach a found zs.
283  */
284 static void
285 zsattach(parent, dev, aux)
286 struct device	*parent;
287 struct device	*dev;
288 void		*aux;
289 {
290 	register struct zs_softc		*zi;
291 	register struct zs_chanstate		*cs;
292 	register volatile struct zsdevice	*addr;
293 		 char				tmp;
294 
295 	addr      = (struct zsdevice *)AD_SCC;
296 	zi        = (struct zs_softc *)dev;
297 	zi->zi_zs = addr;
298 	cs        = zi->zi_cs;
299 
300 	/*
301 	 * Get the command register into a known state.
302 	 */
303 	tmp = addr->zs_chan[ZS_CHAN_A].zc_csr;
304 	tmp = addr->zs_chan[ZS_CHAN_A].zc_csr;
305 	tmp = addr->zs_chan[ZS_CHAN_B].zc_csr;
306 	tmp = addr->zs_chan[ZS_CHAN_B].zc_csr;
307 
308 	/*
309 	 * Do a hardware reset.
310 	 */
311 	ZS_WRITE(&addr->zs_chan[ZS_CHAN_A], 9, ZSWR9_HARD_RESET);
312 	delay(50000);	/*enough ? */
313 	ZS_WRITE(&addr->zs_chan[ZS_CHAN_A], 9, 0);
314 
315 	/*
316 	 * Initialize both channels
317 	 */
318 	zs_loadchannelregs(&addr->zs_chan[ZS_CHAN_A], zs_init_regs);
319 	zs_loadchannelregs(&addr->zs_chan[ZS_CHAN_B], zs_init_regs);
320 
321 	if(machineid & ATARI_TT) {
322 		/*
323 		 * ininitialise TT-MFP timer C: 307200Hz
324 		 * timer C and D share one control register:
325 		 *	bits 0-2 control timer D
326 		 *	bits 4-6 control timer C
327 		 */
328 		int cr = MFP2->mf_tcdcr & 7;
329 		MFP2->mf_tcdcr = cr;		/* stop timer C  */
330 		MFP2->mf_tcdr  = 1;		/* counter 1     */
331 		cr |= T_Q004 << 4;		/* divisor 4     */
332 		MFP2->mf_tcdcr = cr;		/* start timer C */
333 		/*
334 		 * enable scc related interrupts
335 		 */
336 		SCU->vme_mask |= SCU_SCC;
337 
338 		zs_frequencies = zs_freqs_tt;
339 	} else if (machineid & ATARI_FALCON) {
340 		zs_frequencies = zs_freqs_falcon;
341 	} else if (machineid & ATARI_HADES) {
342 		zs_frequencies = zs_freqs_hades;
343 	} else {
344 		zs_frequencies = zs_freqs_generic;
345 	}
346 
347 	/* link into interrupt list with order (A,B) (B=A+1) */
348 	cs[0].cs_next = &cs[1];
349 	cs[1].cs_next = zslist;
350 	zslist        = cs;
351 
352 	cs->cs_unit  = 0;
353 	cs->cs_zc    = &addr->zs_chan[ZS_CHAN_A];
354 	cs++;
355 	cs->cs_unit  = 1;
356 	cs->cs_zc    = &addr->zs_chan[ZS_CHAN_B];
357 
358 	printf(": serial2 on channel a and modem2 on channel b\n");
359 }
360 
361 /*
362  * Open a zs serial port.
363  */
364 int
365 zsopen(dev, flags, mode, p)
366 dev_t		dev;
367 int		flags;
368 int		mode;
369 struct proc	*p;
370 {
371 	register struct tty		*tp;
372 	register struct zs_chanstate	*cs;
373 		 struct zs_softc	*zi;
374 		 int			unit = ZS_UNIT(dev);
375 		 int			zs = unit >> 1;
376 		 int			error, s;
377 
378 	if(zs >= zs_cd.cd_ndevs || (zi = zs_cd.cd_devs[zs]) == NULL)
379 		return (ENXIO);
380 	cs = &zi->zi_cs[unit & 1];
381 
382 	/*
383 	 * When port A (ser02) is selected on the TT, make sure
384 	 * the port is enabled.
385 	 */
386 	if((machineid & ATARI_TT) && !(unit & 1))
387 		ym2149_ser2(1);
388 
389 	if (cs->cs_rbuf == NULL) {
390 		cs->cs_rbuf = malloc(ZLRB_RING_SIZE * sizeof(int), M_DEVBUF,
391 								   M_WAITOK);
392 	}
393 
394 	tp = cs->cs_ttyp;
395 	if(tp == NULL) {
396 		cs->cs_ttyp = tp = ttymalloc();
397 		tty_attach(tp);
398 		tp->t_dev   = dev;
399 		tp->t_oproc = zsstart;
400 		tp->t_param = zsparam;
401 	}
402 
403 	if ((tp->t_state & TS_ISOPEN) &&
404 	    (tp->t_state & TS_XCLUDE) &&
405 	    p->p_ucred->cr_uid != 0)
406 		return (EBUSY);
407 
408 	s  = spltty();
409 
410 	/*
411 	 * Do the following iff this is a first open.
412 	 */
413 	if (!(tp->t_state & TS_ISOPEN) && tp->t_wopen == 0) {
414 		if(tp->t_ispeed == 0) {
415 			tp->t_iflag = TTYDEF_IFLAG;
416 			tp->t_oflag = TTYDEF_OFLAG;
417 			tp->t_cflag = TTYDEF_CFLAG;
418 			tp->t_lflag = TTYDEF_LFLAG;
419 			tp->t_ispeed = tp->t_ospeed = TTYDEF_SPEED;
420 		}
421 		ttychars(tp);
422 		ttsetwater(tp);
423 
424 		(void)zsparam(tp, &tp->t_termios);
425 
426 		/*
427 		 * Turn on DTR.  We must always do this, even if carrier is not
428 		 * present, because otherwise we'd have to use TIOCSDTR
429 		 * immediately after setting CLOCAL, which applications do not
430 		 * expect.  We always assert DTR while the device is open
431 		 * unless explicitly requested to deassert it.
432 		 */
433 		zs_modem(cs, ZSWR5_RTS|ZSWR5_DTR, DMSET);
434 		/* May never get a status intr. if DCD already on. -gwr */
435 		if((cs->cs_rr0 = cs->cs_zc->zc_csr) & ZSRR0_DCD)
436 			tp->t_state |= TS_CARR_ON;
437 		if(cs->cs_softcar)
438 			tp->t_state |= TS_CARR_ON;
439 	}
440 
441 	splx(s);
442 
443 	error = ttyopen(tp, ZS_DIALOUT(dev), (flags & O_NONBLOCK));
444 	if (error)
445 		goto bad;
446 
447 	error = tp->t_linesw->l_open(dev, tp);
448 	if(error)
449 		goto bad;
450 	return (0);
451 
452 bad:
453 	if (!(tp->t_state & TS_ISOPEN) && tp->t_wopen == 0) {
454 		/*
455 		 * We failed to open the device, and nobody else had it opened.
456 		 * Clean up the state as appropriate.
457 		 */
458 		zs_shutdown(cs);
459 	}
460 	return(error);
461 }
462 
463 /*
464  * Close a zs serial port.
465  */
466 int
467 zsclose(dev, flags, mode, p)
468 dev_t		dev;
469 int		flags;
470 int		mode;
471 struct proc	*p;
472 {
473 	register struct zs_chanstate	*cs;
474 	register struct tty		*tp;
475 		 struct zs_softc	*zi;
476 		 int			unit = ZS_UNIT(dev);
477 
478 	zi = zs_cd.cd_devs[unit >> 1];
479 	cs = &zi->zi_cs[unit & 1];
480 	tp = cs->cs_ttyp;
481 
482 	tp->t_linesw->l_close(tp, flags);
483 	ttyclose(tp);
484 
485 	if (!(tp->t_state & TS_ISOPEN) && tp->t_wopen == 0) {
486 		/*
487 		 * Although we got a last close, the device may still be in
488 		 * use; e.g. if this was the dialout node, and there are still
489 		 * processes waiting for carrier on the non-dialout node.
490 		 */
491 		zs_shutdown(cs);
492 	}
493 	return (0);
494 }
495 
496 /*
497  * Read/write zs serial port.
498  */
499 int
500 zsread(dev, uio, flags)
501 dev_t		dev;
502 struct uio	*uio;
503 int		flags;
504 {
505 	register struct zs_chanstate	*cs;
506 	register struct zs_softc	*zi;
507 	register struct tty		*tp;
508 		 int			unit;
509 
510 	unit = ZS_UNIT(dev);
511 	zi   = zs_cd.cd_devs[unit >> 1];
512 	cs   = &zi->zi_cs[unit & 1];
513 	tp   = cs->cs_ttyp;
514 
515 	return(tp->t_linesw->l_read(tp, uio, flags));
516 }
517 
518 int
519 zswrite(dev, uio, flags)
520 dev_t		dev;
521 struct uio	*uio;
522 int		flags;
523 {
524 	register struct zs_chanstate	*cs;
525 	register struct zs_softc	*zi;
526 	register struct tty		*tp;
527 		 int			unit;
528 
529 	unit = ZS_UNIT(dev);
530 	zi   = zs_cd.cd_devs[unit >> 1];
531 	cs   = &zi->zi_cs[unit & 1];
532 	tp   = cs->cs_ttyp;
533 
534 	return(tp->t_linesw->l_write(tp, uio, flags));
535 }
536 
537 int
538 zspoll(dev, events, p)
539 dev_t		dev;
540 int		events;
541 struct proc	*p;
542 {
543 	register struct zs_chanstate	*cs;
544 	register struct zs_softc	*zi;
545 	register struct tty		*tp;
546 		 int			unit;
547 
548 	unit = ZS_UNIT(dev);
549 	zi   = zs_cd.cd_devs[unit >> 1];
550 	cs   = &zi->zi_cs[unit & 1];
551 	tp   = cs->cs_ttyp;
552 
553 	return ((*tp->t_linesw->l_poll)(tp, events, p));
554 }
555 
556 struct tty *
557 zstty(dev)
558 dev_t	dev;
559 {
560 	register struct zs_chanstate	*cs;
561 	register struct zs_softc	*zi;
562 		 int			unit;
563 
564 	unit = ZS_UNIT(dev);
565 	zi   = zs_cd.cd_devs[unit >> 1];
566 	cs   = &zi->zi_cs[unit & 1];
567 	return(cs->cs_ttyp);
568 }
569 
570 /*
571  * ZS hardware interrupt.  Scan all ZS channels.  NB: we know here that
572  * channels are kept in (A,B) pairs.
573  *
574  * Do just a little, then get out; set a software interrupt if more
575  * work is needed.
576  *
577  * We deliberately ignore the vectoring Zilog gives us, and match up
578  * only the number of `reset interrupt under service' operations, not
579  * the order.
580  */
581 
582 int
583 zshard(sr)
584 long sr;
585 {
586 	register struct zs_chanstate	*a;
587 #define	b (a + 1)
588 	register volatile struct zschan *zc;
589 	register int			rr3, intflags = 0, v, i;
590 
591 	do {
592 	    intflags &= ~4;
593 	    for(a = zslist; a != NULL; a = b->cs_next) {
594 		rr3 = ZS_READ(a->cs_zc, 3);
595 		if(rr3 & (ZSRR3_IP_A_RX|ZSRR3_IP_A_TX|ZSRR3_IP_A_STAT)) {
596 			intflags |= 4|2;
597 			zc = a->cs_zc;
598 			i  = a->cs_rbput;
599 			if(rr3 & ZSRR3_IP_A_RX && (v = zsrint(a, zc)) != 0) {
600 				a->cs_rbuf[i++ & ZLRB_RING_MASK] = v;
601 				intflags |= 1;
602 			}
603 			if(rr3 & ZSRR3_IP_A_TX && (v = zsxint(a, zc)) != 0) {
604 				a->cs_rbuf[i++ & ZLRB_RING_MASK] = v;
605 				intflags |= 1;
606 			}
607 			if(rr3 & ZSRR3_IP_A_STAT && (v = zssint(a, zc)) != 0) {
608 				a->cs_rbuf[i++ & ZLRB_RING_MASK] = v;
609 				intflags |= 1;
610 			}
611 			a->cs_rbput = i;
612 		}
613 		if(rr3 & (ZSRR3_IP_B_RX|ZSRR3_IP_B_TX|ZSRR3_IP_B_STAT)) {
614 			intflags |= 4|2;
615 			zc = b->cs_zc;
616 			i  = b->cs_rbput;
617 			if(rr3 & ZSRR3_IP_B_RX && (v = zsrint(b, zc)) != 0) {
618 				b->cs_rbuf[i++ & ZLRB_RING_MASK] = v;
619 				intflags |= 1;
620 			}
621 			if(rr3 & ZSRR3_IP_B_TX && (v = zsxint(b, zc)) != 0) {
622 				b->cs_rbuf[i++ & ZLRB_RING_MASK] = v;
623 				intflags |= 1;
624 			}
625 			if(rr3 & ZSRR3_IP_B_STAT && (v = zssint(b, zc)) != 0) {
626 				b->cs_rbuf[i++ & ZLRB_RING_MASK] = v;
627 				intflags |= 1;
628 			}
629 			b->cs_rbput = i;
630 		}
631 	    }
632 	} while(intflags & 4);
633 #undef b
634 
635 	if(intflags & 1) {
636 		if(BASEPRI(sr)) {
637 			spl1();
638 			zsshortcuts++;
639 			return(zssoft(sr));
640 		}
641 		else if(!cb_scheduled) {
642 			cb_scheduled++;
643 			add_sicallback((si_farg)zssoft, 0, 0);
644 		}
645 	}
646 	return(intflags & 2);
647 }
648 
649 static int
650 zsrint(cs, zc)
651 register struct zs_chanstate	*cs;
652 register volatile struct zschan	*zc;
653 {
654 	register int c;
655 
656 	/*
657 	 * First read the status, because read of the received char
658 	 * destroy the status of this char.
659 	 */
660 	c = ZS_READ(zc, 1);
661 	c |= (zc->zc_data << 8);
662 
663 	/* clear receive error & interrupt condition */
664 	zc->zc_csr = ZSWR0_RESET_ERRORS;
665 	zc->zc_csr = ZSWR0_CLR_INTR;
666 
667 	return(ZRING_MAKE(ZRING_RINT, c));
668 }
669 
670 static int
671 zsxint(cs, zc)
672 register struct zs_chanstate	*cs;
673 register volatile struct zschan	*zc;
674 {
675 	register int i = cs->cs_tbc;
676 
677 	if(i == 0) {
678 		zc->zc_csr = ZSWR0_RESET_TXINT;
679 		zc->zc_csr = ZSWR0_CLR_INTR;
680 		return(ZRING_MAKE(ZRING_XINT, 0));
681 	}
682 	cs->cs_tbc = i - 1;
683 	zc->zc_data = *cs->cs_tba++;
684 	zc->zc_csr = ZSWR0_CLR_INTR;
685 	return (0);
686 }
687 
688 static int
689 zssint(cs, zc)
690 register struct zs_chanstate	*cs;
691 register volatile struct zschan	*zc;
692 {
693 	register int rr0;
694 
695 	rr0 = zc->zc_csr;
696 	zc->zc_csr = ZSWR0_RESET_STATUS;
697 	zc->zc_csr = ZSWR0_CLR_INTR;
698 	/*
699 	 * The chip's hardware flow control is, as noted in zsreg.h,
700 	 * busted---if the DCD line goes low the chip shuts off the
701 	 * receiver (!).  If we want hardware CTS flow control but do
702 	 * not have it, and carrier is now on, turn HFC on; if we have
703 	 * HFC now but carrier has gone low, turn it off.
704 	 */
705 	if(rr0 & ZSRR0_DCD) {
706 		if(cs->cs_ttyp->t_cflag & CCTS_OFLOW &&
707 		    (cs->cs_creg[3] & ZSWR3_HFC) == 0) {
708 			cs->cs_creg[3] |= ZSWR3_HFC;
709 			ZS_WRITE(zc, 3, cs->cs_creg[3]);
710 		}
711 	}
712 	else {
713 		if (cs->cs_creg[3] & ZSWR3_HFC) {
714 			cs->cs_creg[3] &= ~ZSWR3_HFC;
715 			ZS_WRITE(zc, 3, cs->cs_creg[3]);
716 		}
717 	}
718 	return(ZRING_MAKE(ZRING_SINT, rr0));
719 }
720 
721 /*
722  * Print out a ring or fifo overrun error message.
723  */
724 static void
725 zsoverrun(unit, ptime, what)
726 int	unit;
727 long	*ptime;
728 char	*what;
729 {
730 
731 	if(*ptime != time.tv_sec) {
732 		*ptime = time.tv_sec;
733 		log(LOG_WARNING, "zs%d%c: %s overrun\n", unit >> 1,
734 		    (unit & 1) + 'a', what);
735 	}
736 }
737 
738 /*
739  * ZS software interrupt.  Scan all channels for deferred interrupts.
740  */
741 int
742 zssoft(sr)
743 long sr;
744 {
745     register struct zs_chanstate	*cs;
746     register volatile struct zschan	*zc;
747     register struct linesw		*line;
748     register struct tty			*tp;
749     register int			get, n, c, cc, unit, s;
750  	     int			retval = 0;
751 
752     cb_scheduled = 0;
753     s = spltty();
754     for(cs = zslist; cs != NULL; cs = cs->cs_next) {
755 	get = cs->cs_rbget;
756 again:
757 	n = cs->cs_rbput;	/* atomic			*/
758 	if(get == n)		/* nothing more on this line	*/
759 		continue;
760 	retval = 1;
761 	unit   = cs->cs_unit;	/* set up to handle interrupts	*/
762 	zc     = cs->cs_zc;
763 	tp     = cs->cs_ttyp;
764 	line   = tp->t_linesw;
765 	/*
766 	 * Compute the number of interrupts in the receive ring.
767 	 * If the count is overlarge, we lost some events, and
768 	 * must advance to the first valid one.  It may get
769 	 * overwritten if more data are arriving, but this is
770 	 * too expensive to check and gains nothing (we already
771 	 * lost out; all we can do at this point is trade one
772 	 * kind of loss for another).
773 	 */
774 	n -= get;
775 	if(n > ZLRB_RING_SIZE) {
776 		zsoverrun(unit, &cs->cs_rotime, "ring");
777 		get += n - ZLRB_RING_SIZE;
778 		n    = ZLRB_RING_SIZE;
779 	}
780 	while(--n >= 0) {
781 		/* race to keep ahead of incoming interrupts */
782 		c = cs->cs_rbuf[get++ & ZLRB_RING_MASK];
783 		switch (ZRING_TYPE(c)) {
784 
785 		case ZRING_RINT:
786 			c = ZRING_VALUE(c);
787 			if(c & ZSRR1_DO)
788 				zsoverrun(unit, &cs->cs_fotime, "fifo");
789 			cc = c >> 8;
790 			if(c & ZSRR1_FE)
791 				cc |= TTY_FE;
792 			if(c & ZSRR1_PE)
793 				cc |= TTY_PE;
794 			line->l_rint(cc, tp);
795 			break;
796 
797 		case ZRING_XINT:
798 			/*
799 			 * Transmit done: change registers and resume,
800 			 * or clear BUSY.
801 			 */
802 			if(cs->cs_heldchange) {
803 				int sps;
804 
805 				sps = splzs();
806 				c = zc->zc_csr;
807 				if((c & ZSRR0_DCD) == 0)
808 					cs->cs_preg[3] &= ~ZSWR3_HFC;
809 				bcopy((caddr_t)cs->cs_preg,
810 				    (caddr_t)cs->cs_creg, 16);
811 				zs_loadchannelregs(zc, cs->cs_creg);
812 				splx(sps);
813 				cs->cs_heldchange = 0;
814 				if(cs->cs_heldtbc
815 					&& (tp->t_state & TS_TTSTOP) == 0) {
816 					cs->cs_tbc = cs->cs_heldtbc - 1;
817 					zc->zc_data = *cs->cs_tba++;
818 					goto again;
819 				}
820 			}
821 			tp->t_state &= ~TS_BUSY;
822 			if(tp->t_state & TS_FLUSH)
823 				tp->t_state &= ~TS_FLUSH;
824 			else ndflush(&tp->t_outq,cs->cs_tba
825 						- (caddr_t)tp->t_outq.c_cf);
826 			line->l_start(tp);
827 			break;
828 
829 		case ZRING_SINT:
830 			/*
831 			 * Status line change.  HFC bit is run in
832 			 * hardware interrupt, to avoid locking
833 			 * at splzs here.
834 			 */
835 			c = ZRING_VALUE(c);
836 			if((c ^ cs->cs_rr0) & ZSRR0_DCD) {
837 				cc = (c & ZSRR0_DCD) != 0;
838 				if(line->l_modem(tp, cc) == 0)
839 					zs_modem(cs, ZSWR5_RTS|ZSWR5_DTR,
840 							cc ? DMBIS : DMBIC);
841 			}
842 			cs->cs_rr0 = c;
843 			break;
844 
845 		default:
846 			log(LOG_ERR, "zs%d%c: bad ZRING_TYPE (%x)\n",
847 			    unit >> 1, (unit & 1) + 'a', c);
848 			break;
849 		}
850 	}
851 	cs->cs_rbget = get;
852 	goto again;
853     }
854     splx(s);
855     return (retval);
856 }
857 
858 int
859 zsioctl(dev, cmd, data, flag, p)
860 dev_t		dev;
861 u_long		cmd;
862 caddr_t		data;
863 int		flag;
864 struct proc	*p;
865 {
866 		 int			unit = ZS_UNIT(dev);
867 		 struct zs_softc	*zi = zs_cd.cd_devs[unit >> 1];
868 	register struct tty		*tp = zi->zi_cs[unit & 1].cs_ttyp;
869 	register int			error, s;
870 	register struct zs_chanstate	*cs = &zi->zi_cs[unit & 1];
871 
872 	error = tp->t_linesw->l_ioctl(tp, cmd, data, flag, p);
873 	if(error != EPASSTHROUGH)
874 		return(error);
875 
876 	error = ttioctl(tp, cmd, data, flag, p);
877 	if(error !=EPASSTHROUGH)
878 		return (error);
879 
880 	switch (cmd) {
881 	case TIOCSBRK:
882 		s = splzs();
883 		cs->cs_preg[5] |= ZSWR5_BREAK;
884 		cs->cs_creg[5] |= ZSWR5_BREAK;
885 		ZS_WRITE(cs->cs_zc, 5, cs->cs_creg[5]);
886 		splx(s);
887 		break;
888 	case TIOCCBRK:
889 		s = splzs();
890 		cs->cs_preg[5] &= ~ZSWR5_BREAK;
891 		cs->cs_creg[5] &= ~ZSWR5_BREAK;
892 		ZS_WRITE(cs->cs_zc, 5, cs->cs_creg[5]);
893 		splx(s);
894 		break;
895 	case TIOCGFLAGS: {
896 		int bits = 0;
897 
898 		if(cs->cs_softcar)
899 			bits |= TIOCFLAG_SOFTCAR;
900 		if(cs->cs_creg[15] & ZSWR15_DCD_IE)
901 			bits |= TIOCFLAG_CLOCAL;
902 		if(cs->cs_creg[3] & ZSWR3_HFC)
903 			bits |= TIOCFLAG_CRTSCTS;
904 		*(int *)data = bits;
905 		break;
906 	}
907 	case TIOCSFLAGS: {
908 		int userbits = 0;
909 
910 		error = suser(p->p_ucred, &p->p_acflag);
911 		if(error != 0)
912 			return (EPERM);
913 
914 		userbits = *(int *)data;
915 
916 		/*
917 		 * can have `local' or `softcar', and `rtscts' or `mdmbuf'
918 		 # defaulting to software flow control.
919 		 */
920 		if(userbits & TIOCFLAG_SOFTCAR && userbits & TIOCFLAG_CLOCAL)
921 			return(EINVAL);
922 		if(userbits & TIOCFLAG_MDMBUF)	/* don't support this (yet?) */
923 			return(ENODEV);
924 
925 		s = splzs();
926 		if((userbits & TIOCFLAG_SOFTCAR)) {
927 			cs->cs_softcar = 1;	/* turn on softcar */
928 			cs->cs_preg[15] &= ~ZSWR15_DCD_IE; /* turn off dcd */
929 			cs->cs_creg[15] &= ~ZSWR15_DCD_IE;
930 			ZS_WRITE(cs->cs_zc, 15, cs->cs_creg[15]);
931 		}
932 		else if(userbits & TIOCFLAG_CLOCAL) {
933 			cs->cs_softcar = 0; 	/* turn off softcar */
934 			cs->cs_preg[15] |= ZSWR15_DCD_IE; /* turn on dcd */
935 			cs->cs_creg[15] |= ZSWR15_DCD_IE;
936 			ZS_WRITE(cs->cs_zc, 15, cs->cs_creg[15]);
937 			tp->t_termios.c_cflag |= CLOCAL;
938 		}
939 		if(userbits & TIOCFLAG_CRTSCTS) {
940 			cs->cs_preg[15] |= ZSWR15_CTS_IE;
941 			cs->cs_creg[15] |= ZSWR15_CTS_IE;
942 			ZS_WRITE(cs->cs_zc, 15, cs->cs_creg[15]);
943 			cs->cs_preg[3] |= ZSWR3_HFC;
944 			cs->cs_creg[3] |= ZSWR3_HFC;
945 			ZS_WRITE(cs->cs_zc, 3, cs->cs_creg[3]);
946 			tp->t_termios.c_cflag |= CRTSCTS;
947 		}
948 		else {
949 			/* no mdmbuf, so we must want software flow control */
950 			cs->cs_preg[15] &= ~ZSWR15_CTS_IE;
951 			cs->cs_creg[15] &= ~ZSWR15_CTS_IE;
952 			ZS_WRITE(cs->cs_zc, 15, cs->cs_creg[15]);
953 			cs->cs_preg[3] &= ~ZSWR3_HFC;
954 			cs->cs_creg[3] &= ~ZSWR3_HFC;
955 			ZS_WRITE(cs->cs_zc, 3, cs->cs_creg[3]);
956 			tp->t_termios.c_cflag &= ~CRTSCTS;
957 		}
958 		splx(s);
959 		break;
960 	}
961 	case TIOCSDTR:
962 		zs_modem(cs, ZSWR5_DTR, DMBIS);
963 		break;
964 	case TIOCCDTR:
965 		zs_modem(cs, ZSWR5_DTR, DMBIC);
966 		break;
967 	case TIOCMGET:
968 		zs_modem(cs, 0, DMGET);
969 		break;
970 	case TIOCMSET:
971 	case TIOCMBIS:
972 	case TIOCMBIC:
973 	default:
974 		return (EPASSTHROUGH);
975 	}
976 	return (0);
977 }
978 
979 /*
980  * Start or restart transmission.
981  */
982 static void
983 zsstart(tp)
984 register struct tty *tp;
985 {
986 	register struct zs_chanstate	*cs;
987 	register int			s, nch;
988 		 int			unit = ZS_UNIT(tp->t_dev);
989 		 struct zs_softc	*zi = zs_cd.cd_devs[unit >> 1];
990 
991 	cs = &zi->zi_cs[unit & 1];
992 	s  = spltty();
993 
994 	/*
995 	 * If currently active or delaying, no need to do anything.
996 	 */
997 	if(tp->t_state & (TS_TIMEOUT | TS_BUSY | TS_TTSTOP))
998 		goto out;
999 
1000 	/*
1001 	 * If there are sleepers, and output has drained below low
1002 	 * water mark, awaken.
1003 	 */
1004 	if(tp->t_outq.c_cc <= tp->t_lowat) {
1005 		if(tp->t_state & TS_ASLEEP) {
1006 			tp->t_state &= ~TS_ASLEEP;
1007 			wakeup((caddr_t)&tp->t_outq);
1008 		}
1009 		selwakeup(&tp->t_wsel);
1010 	}
1011 
1012 	nch = ndqb(&tp->t_outq, 0);	/* XXX */
1013 	if(nch) {
1014 		register char *p = tp->t_outq.c_cf;
1015 
1016 		/* mark busy, enable tx done interrupts, & send first byte */
1017 		tp->t_state |= TS_BUSY;
1018 		(void) splzs();
1019 		cs->cs_preg[1] |= ZSWR1_TIE;
1020 		cs->cs_creg[1] |= ZSWR1_TIE;
1021 		ZS_WRITE(cs->cs_zc, 1, cs->cs_creg[1]);
1022 		cs->cs_zc->zc_data = *p;
1023 		cs->cs_tba = p + 1;
1024 		cs->cs_tbc = nch - 1;
1025 	} else {
1026 		/*
1027 		 * Nothing to send, turn off transmit done interrupts.
1028 		 * This is useful if something is doing polled output.
1029 		 */
1030 		(void) splzs();
1031 		cs->cs_preg[1] &= ~ZSWR1_TIE;
1032 		cs->cs_creg[1] &= ~ZSWR1_TIE;
1033 		ZS_WRITE(cs->cs_zc, 1, cs->cs_creg[1]);
1034 	}
1035 out:
1036 	splx(s);
1037 }
1038 
1039 /*
1040  * Stop output, e.g., for ^S or output flush.
1041  */
1042 void
1043 zsstop(tp, flag)
1044 register struct tty	*tp;
1045 	 int		flag;
1046 {
1047 	register struct zs_chanstate	*cs;
1048 	register int			s, unit = ZS_UNIT(tp->t_dev);
1049 		 struct zs_softc	*zi = zs_cd.cd_devs[unit >> 1];
1050 
1051 	cs = &zi->zi_cs[unit & 1];
1052 	s  = splzs();
1053 	if(tp->t_state & TS_BUSY) {
1054 		/*
1055 		 * Device is transmitting; must stop it.
1056 		 */
1057 		cs->cs_tbc = 0;
1058 		if ((tp->t_state & TS_TTSTOP) == 0)
1059 			tp->t_state |= TS_FLUSH;
1060 	}
1061 	splx(s);
1062 }
1063 
1064 static void
1065 zs_shutdown(cs)
1066 	struct zs_chanstate	*cs;
1067 {
1068 	struct tty	*tp = cs->cs_ttyp;
1069 	int		s;
1070 
1071 	s = splzs();
1072 
1073 	/*
1074 	 * Hang up if necessary.  Wait a bit, so the other side has time to
1075 	 * notice even if we immediately open the port again.
1076 	 */
1077 	if(tp->t_cflag & HUPCL) {
1078 		zs_modem(cs, 0, DMSET);
1079 		(void)tsleep((caddr_t)cs, TTIPRI, ttclos, hz);
1080 	}
1081 
1082 	/* Clear any break condition set with TIOCSBRK. */
1083 	if(cs->cs_creg[5] & ZSWR5_BREAK) {
1084 		cs->cs_preg[5] &= ~ZSWR5_BREAK;
1085 		cs->cs_creg[5] &= ~ZSWR5_BREAK;
1086 		ZS_WRITE(cs->cs_zc, 5, cs->cs_creg[5]);
1087 	}
1088 
1089 	/*
1090 	 * Drop all lines and cancel interrupts
1091 	 */
1092 	zs_loadchannelregs(cs->cs_zc, zs_init_regs);
1093 	splx(s);
1094 }
1095 
1096 /*
1097  * Set ZS tty parameters from termios.
1098  *
1099  * This routine makes use of the fact that only registers
1100  * 1, 3, 4, 5, 9, 10, 11, 12, 13, 14, and 15 are written.
1101  */
1102 static int
1103 zsparam(tp, t)
1104 register struct tty	*tp;
1105 register struct termios	*t;
1106 {
1107 		 int			unit = ZS_UNIT(tp->t_dev);
1108 		 struct zs_softc	*zi = zs_cd.cd_devs[unit >> 1];
1109 	register struct zs_chanstate	*cs = &zi->zi_cs[unit & 1];
1110 		 int			cdiv, clkm, brgm, tcon;
1111 	register int			tmp, tmp5, cflag, s;
1112 
1113 	tmp  = t->c_ospeed;
1114 	tmp5 = t->c_ispeed;
1115 	if(tmp < 0 || (tmp5 && tmp5 != tmp))
1116 		return(EINVAL);
1117 	if(tmp == 0) {
1118 		/* stty 0 => drop DTR and RTS */
1119 		zs_modem(cs, 0, DMSET);
1120 		return(0);
1121 	}
1122 	tmp = zsbaudrate(unit, tmp, &cdiv, &clkm, &brgm, &tcon);
1123 	if (tmp < 0)
1124 		return(EINVAL);
1125 	tp->t_ispeed = tp->t_ospeed = tmp;
1126 
1127 	cflag = tp->t_cflag = t->c_cflag;
1128 	if (cflag & CSTOPB)
1129 		cdiv |= ZSWR4_TWOSB;
1130 	else
1131 		cdiv |= ZSWR4_ONESB;
1132 	if (!(cflag & PARODD))
1133 		cdiv |= ZSWR4_EVENP;
1134 	if (cflag & PARENB)
1135 		cdiv |= ZSWR4_PARENB;
1136 
1137 	switch(cflag & CSIZE) {
1138 	case CS5:
1139 		tmp  = ZSWR3_RX_5;
1140 		tmp5 = ZSWR5_TX_5;
1141 		break;
1142 	case CS6:
1143 		tmp  = ZSWR3_RX_6;
1144 		tmp5 = ZSWR5_TX_6;
1145 		break;
1146 	case CS7:
1147 		tmp  = ZSWR3_RX_7;
1148 		tmp5 = ZSWR5_TX_7;
1149 		break;
1150 	case CS8:
1151 	default:
1152 		tmp  = ZSWR3_RX_8;
1153 		tmp5 = ZSWR5_TX_8;
1154 		break;
1155 	}
1156 	tmp  |= ZSWR3_RX_ENABLE;
1157 	tmp5 |= ZSWR5_TX_ENABLE | ZSWR5_DTR | ZSWR5_RTS;
1158 
1159 	/*
1160 	 * Block interrupts so that state will not
1161 	 * be altered until we are done setting it up.
1162 	 */
1163 	s = splzs();
1164 	cs->cs_preg[4]  = cdiv;
1165 	cs->cs_preg[11] = clkm;
1166 	cs->cs_preg[12] = tcon;
1167 	cs->cs_preg[13] = tcon >> 8;
1168 	cs->cs_preg[14] = brgm;
1169 	cs->cs_preg[1]  = ZSWR1_RIE | ZSWR1_TIE | ZSWR1_SIE;
1170 	cs->cs_preg[9]  = ZSWR9_MASTER_IE | ZSWR9_VECTOR_INCL_STAT;
1171 	cs->cs_preg[10] = ZSWR10_NRZ;
1172 	cs->cs_preg[15] = ZSWR15_BREAK_IE | ZSWR15_DCD_IE;
1173 
1174 	/*
1175 	 * Output hardware flow control on the chip is horrendous: if
1176 	 * carrier detect drops, the receiver is disabled.  Hence we
1177 	 * can only do this when the carrier is on.
1178 	 */
1179 	if(cflag & CCTS_OFLOW && cs->cs_zc->zc_csr & ZSRR0_DCD)
1180 		tmp |= ZSWR3_HFC;
1181 	cs->cs_preg[3] = tmp;
1182 	cs->cs_preg[5] = tmp5;
1183 
1184 	/*
1185 	 * If nothing is being transmitted, set up new current values,
1186 	 * else mark them as pending.
1187 	 */
1188 	if(cs->cs_heldchange == 0) {
1189 		if (cs->cs_ttyp->t_state & TS_BUSY) {
1190 			cs->cs_heldtbc = cs->cs_tbc;
1191 			cs->cs_tbc = 0;
1192 			cs->cs_heldchange = 1;
1193 		} else {
1194 			bcopy((caddr_t)cs->cs_preg, (caddr_t)cs->cs_creg, 16);
1195 			zs_loadchannelregs(cs->cs_zc, cs->cs_creg);
1196 		}
1197 	}
1198 	splx(s);
1199 	return (0);
1200 }
1201 
1202 /*
1203  * search for the best matching baudrate
1204  */
1205 static int
1206 zsbaudrate(unit, wanted, divisor, clockmode, brgenmode, timeconst)
1207 int	unit, wanted, *divisor, *clockmode, *brgenmode, *timeconst;
1208 {
1209 	int	bestdiff, bestbps, source;
1210 
1211 	bestdiff = bestbps = 0;
1212 	unit = (unit & 1) << 2;
1213 	for (source = 0; source < 4; ++source) {
1214 		long	freq = zs_frequencies[unit + source];
1215 		int	diff, bps, div, clkm, brgm, tcon;
1216 
1217 		bps = div = clkm = brgm = tcon = 0;
1218 		switch (source) {
1219 			case 0:	/* BRgen, PCLK */
1220 				brgm = ZSWR14_BAUD_ENA|ZSWR14_BAUD_FROM_PCLK;
1221 				break;
1222 			case 1:	/* BRgen, RTxC */
1223 				brgm = ZSWR14_BAUD_ENA;
1224 				break;
1225 			case 2: /* RTxC */
1226 				clkm = ZSWR11_RXCLK_RTXC|ZSWR11_TXCLK_RTXC;
1227 				break;
1228 			case 3: /* TRxC */
1229 				clkm = ZSWR11_RXCLK_TRXC|ZSWR11_TXCLK_TRXC;
1230 				break;
1231 		}
1232 		switch (source) {
1233 			case 0:
1234 			case 1:
1235 				div  = ZSWR4_CLK_X16;
1236 				clkm = ZSWR11_RXCLK_BAUD|ZSWR11_TXCLK_BAUD;
1237 				tcon = BPS_TO_TCONST(freq, wanted);
1238 				if (tcon < 0)
1239 					tcon = 0;
1240 				bps  = TCONST_TO_BPS(freq, tcon);
1241 				break;
1242 			case 2:
1243 			case 3:
1244 			{	int	b1 = freq / 16, d1 = abs(b1 - wanted);
1245 				int	b2 = freq / 32, d2 = abs(b2 - wanted);
1246 				int	b3 = freq / 64, d3 = abs(b3 - wanted);
1247 
1248 				if (d1 < d2 && d1 < d3) {
1249 					div = ZSWR4_CLK_X16;
1250 					bps = b1;
1251 				} else if (d2 < d3 && d2 < d1) {
1252 					div = ZSWR4_CLK_X32;
1253 					bps = b2;
1254 				} else {
1255 					div = ZSWR4_CLK_X64;
1256 					bps = b3;
1257 				}
1258 				brgm = tcon = 0;
1259 				break;
1260 			}
1261 		}
1262 		diff = abs(bps - wanted);
1263 		if (!source || diff < bestdiff) {
1264 			*divisor   = div;
1265 			*clockmode = clkm;
1266 			*brgenmode = brgm;
1267 			*timeconst = tcon;
1268 			bestbps    = bps;
1269 			bestdiff   = diff;
1270 			if (diff == 0)
1271 				break;
1272 		}
1273 	}
1274 	/* Allow deviations upto 5% */
1275 	if (20 * bestdiff > wanted)
1276 		return -1;
1277 	return bestbps;
1278 }
1279 
1280 /*
1281  * Raise or lower modem control (DTR/RTS) signals.  If a character is
1282  * in transmission, the change is deferred.
1283  */
1284 static int
1285 zs_modem(cs, bits, how)
1286 struct zs_chanstate	*cs;
1287 int			bits, how;
1288 {
1289 	int s, mbits;
1290 
1291 	bits  &= ZSWR5_DTR | ZSWR5_RTS;
1292 
1293 	s = splzs();
1294 	mbits  = cs->cs_preg[5] &  (ZSWR5_DTR | ZSWR5_RTS);
1295 
1296 	switch(how) {
1297 		case DMSET:
1298 				mbits  = bits;
1299 				break;
1300 		case DMBIS:
1301 				mbits |= bits;
1302 				break;
1303 		case DMBIC:
1304 				mbits &= ~bits;
1305 				break;
1306 		case DMGET:
1307 				splx(s);
1308 				return(mbits);
1309 	}
1310 
1311 	cs->cs_preg[5] = (cs->cs_preg[5] & ~(ZSWR5_DTR | ZSWR5_RTS)) | mbits;
1312 	if(cs->cs_heldchange == 0) {
1313 		if(cs->cs_ttyp->t_state & TS_BUSY) {
1314 			cs->cs_heldtbc = cs->cs_tbc;
1315 			cs->cs_tbc = 0;
1316 			cs->cs_heldchange = 1;
1317 		}
1318 		else {
1319 			ZS_WRITE(cs->cs_zc, 5, cs->cs_creg[5]);
1320 		}
1321 	}
1322 	splx(s);
1323 	return(0);
1324 }
1325 
1326 /*
1327  * Write the given register set to the given zs channel in the proper order.
1328  * The channel must not be transmitting at the time.  The receiver will
1329  * be disabled for the time it takes to write all the registers.
1330  */
1331 static void
1332 zs_loadchannelregs(zc, reg)
1333 volatile struct zschan	*zc;
1334 u_char			*reg;
1335 {
1336 	int i;
1337 
1338 	zc->zc_csr = ZSM_RESET_ERR;	/* reset error condition */
1339 	i = zc->zc_data;		/* drain fifo */
1340 	i = zc->zc_data;
1341 	i = zc->zc_data;
1342 	ZS_WRITE(zc,  4, reg[4]);
1343 	ZS_WRITE(zc, 10, reg[10]);
1344 	ZS_WRITE(zc,  3, reg[3] & ~ZSWR3_RX_ENABLE);
1345 	ZS_WRITE(zc,  5, reg[5] & ~ZSWR5_TX_ENABLE);
1346 	ZS_WRITE(zc,  1, reg[1]);
1347 	ZS_WRITE(zc,  9, reg[9]);
1348 	ZS_WRITE(zc, 11, reg[11]);
1349 	ZS_WRITE(zc, 12, reg[12]);
1350 	ZS_WRITE(zc, 13, reg[13]);
1351 	ZS_WRITE(zc, 14, reg[14]);
1352 	ZS_WRITE(zc, 15, reg[15]);
1353 	ZS_WRITE(zc,  3, reg[3]);
1354 	ZS_WRITE(zc,  5, reg[5]);
1355 }
1356 #endif /* NZS > 1 */
1357