zs.c revision 1.81
1/*	$NetBSD: zs.c,v 1.81 2023/01/06 10:28:28 tsutsui 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 *
60 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
61 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
62 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
63 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
64 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
65 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
66 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
67 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
68 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
69 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
70 * POSSIBILITY OF SUCH DAMAGE.
71 */
72
73/*
74 * Zilog Z8530 (ZSCC) driver.
75 *
76 * Runs two tty ports (modem2 and serial2) on zs0.
77 *
78 * This driver knows far too much about chip to usage mappings.
79 */
80
81#include <sys/cdefs.h>
82__KERNEL_RCSID(0, "$NetBSD: zs.c,v 1.81 2023/01/06 10:28:28 tsutsui Exp $");
83
84#include <sys/param.h>
85#include <sys/systm.h>
86#include <sys/proc.h>
87#include <sys/device.h>
88#include <sys/conf.h>
89#include <sys/file.h>
90#include <sys/ioctl.h>
91#include <sys/kmem.h>
92#include <sys/tty.h>
93#include <sys/time.h>
94#include <sys/kernel.h>
95#include <sys/syslog.h>
96#include <sys/kauth.h>
97
98#include <machine/cpu.h>
99#include <machine/iomap.h>
100#include <machine/scu.h>
101#include <machine/mfp.h>
102#include <atari/dev/ym2149reg.h>
103
104#include <dev/ic/z8530reg.h>
105#include <atari/dev/zsvar.h>
106
107#include "ioconf.h"
108
109#include "zs.h"
110#if NZS > 1
111#error "This driver supports only 1 85C30!"
112#endif
113
114#if NZS > 0
115
116#define PCLK	(8053976)	/* PCLK pin input clock rate */
117#define PCLK_HD	(9600 * 1536)	/* PCLK on Hades pin input clock rate */
118
119#define splzs	spl5
120
121/*
122 * Software state per found chip.
123 */
124struct zs_softc {
125	device_t sc_dev;		/* base device */
126	struct zs_chanstate *sc_cs[2];	/* chan A and B software state */
127
128	struct zs_chanstate sc_cs_store[2];
129	void *sc_sicookie;		/* for callback */
130};
131
132/*
133 * Define the registers for a closed port
134 */
135static uint8_t zs_init_regs[16] = {
136/*  0 */	0,
137/*  1 */	0,
138/*  2 */	0x60,
139/*  3 */	0,
140/*  4 */	0,
141/*  5 */	0,
142/*  6 */	0,
143/*  7 */	0,
144/*  8 */	0,
145/*  9 */	ZSWR9_MASTER_IE | ZSWR9_VECTOR_INCL_STAT,
146/* 10 */	ZSWR10_NRZ,
147/* 11 */	ZSWR11_TXCLK_BAUD | ZSWR11_RXCLK_BAUD,
148/* 12 */	0,
149/* 13 */	0,
150/* 14 */	ZSWR14_BAUD_FROM_PCLK | ZSWR14_BAUD_ENA,
151/* 15 */	0
152};
153
154/*
155 * Define the machine dependent clock frequencies
156 * If BRgen feeds sender/receiver we always use a
157 * divisor 16; therefore the division by 16 can as
158 * well be done here.
159 */
160static const u_long zs_freqs_tt[] = {
161	/*
162	 * Atari TT, RTxCB is generated by TT-MFP timer C,
163	 * which is set to 307.2 kHz during initialisation
164	 * and never changed afterwards.
165	 */
166	PCLK/16,	/* BRgen, PCLK,  divisor 16	*/
167	 229500,	/* BRgen, RTxCA, divisor 16	*/
168	3672000,	/* RTxCA, from PCLK4		*/
169	      0,	/* TRxCA, external		*/
170
171	PCLK/16,	/* BRgen, PCLK,  divisor 16	*/
172	  19200,	/* BRgen, RTxCB, divisor 16	*/
173	 307200,	/* RTxCB, from TT-MFP TCO	*/
174	2457600		/* TRxCB, from BCLK		*/
175};
176
177static const u_long zs_freqs_falcon[] = {
178	/*
179	 * Atari Falcon, XXX no specs available, this might be wrong
180	 */
181	PCLK/16,	/* BRgen, PCLK,  divisor 16	*/
182	 229500,	/* BRgen, RTxCA, divisor 16	*/
183	3672000,	/* RTxCA, ???			*/
184	      0,	/* TRxCA, external		*/
185
186	PCLK/16,	/* BRgen, PCLK,  divisor 16	*/
187	 229500,	/* BRgen, RTxCB, divisor 16	*/
188	3672000,	/* RTxCB, ???			*/
189	2457600		/* TRxCB, ???			*/
190};
191
192static const u_long zs_freqs_hades[] = {
193	/*
194	 * XXX: Channel-A unchecked!!!!!
195	 */
196     PCLK_HD/16,	/* BRgen, PCLK,  divisor 16	*/
197	 229500,	/* BRgen, RTxCA, divisor 16	*/
198	3672000,	/* RTxCA, from PCLK4		*/
199	      0,	/* TRxCA, external		*/
200
201     PCLK_HD/16,	/* BRgen, PCLK,  divisor 16	*/
202	 235550,	/* BRgen, RTxCB, divisor 16	*/
203	3768800,	/* RTxCB, 3.7688MHz		*/
204	3768800		/* TRxCB, 3.7688MHz		*/
205};
206
207static const u_long zs_freqs_generic[] = {
208	/*
209	 * other machines, assume only PCLK is available
210	 */
211	PCLK/16,	/* BRgen, PCLK,  divisor 16	*/
212	      0,	/* BRgen, RTxCA, divisor 16	*/
213	      0,	/* RTxCA, unknown		*/
214	      0,	/* TRxCA, unknown		*/
215
216	PCLK/16,	/* BRgen, PCLK,  divisor 16	*/
217	      0,	/* BRgen, RTxCB, divisor 16	*/
218	      0,	/* RTxCB, unknown		*/
219	      0		/* TRxCB, unknown		*/
220};
221static const u_long *zs_frequencies;
222
223/* Definition of the driver for autoconfig. */
224static int	zsmatch(device_t, cfdata_t, void *);
225static void	zsattach(device_t, device_t, void *);
226
227CFATTACH_DECL_NEW(zs, sizeof(struct zs_softc),
228    zsmatch, zsattach, NULL, NULL);
229
230/* {b,c}devsw[] function prototypes */
231static dev_type_open(zsopen);
232static dev_type_close(zsclose);
233static dev_type_read(zsread);
234static dev_type_write(zswrite);
235static dev_type_ioctl(zsioctl);
236static dev_type_stop(zsstop);
237static dev_type_tty(zstty);
238static dev_type_poll(zspoll);
239
240const struct cdevsw zs_cdevsw = {
241	.d_open = zsopen,
242	.d_close = zsclose,
243	.d_read = zsread,
244	.d_write = zswrite,
245	.d_ioctl = zsioctl,
246	.d_stop = zsstop,
247	.d_tty = zstty,
248	.d_poll = zspoll,
249	.d_mmap = nommap,
250	.d_kqfilter = ttykqfilter,
251	.d_discard = nodiscard,
252	.d_flag = D_TTY
253};
254
255/* Interrupt handlers. */
256static int	zshard(void *);
257static int	zssoft(void *);
258static int	zsrint(struct zs_chanstate *, struct zschan *);
259static int	zsxint(struct zs_chanstate *, struct zschan *);
260static int	zssint(struct zs_chanstate *, struct zschan *);
261
262/* Routines called from other code. */
263static void	zsstart(struct tty *);
264
265/* Routines purely local to this driver. */
266static void	zsoverrun(int, long *, const char *);
267static int	zsparam(struct tty *, struct termios *);
268static int	zsbaudrate(int, int, int *, int *, int *, int *);
269static int	zs_modem(struct zs_chanstate *, int, int);
270static void	zs_loadchannelregs(struct zschan *, uint8_t *);
271static void	zs_shutdown(struct zs_chanstate *);
272
273static int
274zsmatch(device_t parent, cfdata_t cf, void *aux)
275{
276	static int zs_matched = 0;
277
278	if (strcmp("zs", aux) || zs_matched)
279		return 0;
280	zs_matched = 1;
281	return 1;
282}
283
284/*
285 * Attach a found zs.
286 */
287static void
288zsattach(device_t parent, device_t self, void *aux)
289{
290	struct zs_softc *sc;
291	struct zsdevice *zs;
292	struct zschan *zc;
293	struct zs_chanstate *cs;
294	int channel;
295
296	sc = device_private(self);
297	sc->sc_dev = self;
298
299	printf(": serial2 on channel a and modem2 on channel b\n");
300
301	zs = (struct zsdevice *)AD_SCC;
302
303	for (channel = 0; channel < 2; channel++) {
304		cs = &sc->sc_cs_store[channel];
305		sc->sc_cs[channel] = cs;
306
307		cs->cs_unit = channel;
308		cs->cs_zc = zc =
309		    (channel == 0) ?  &zs->zs_chan_a : &zs->zs_chan_b;
310		/*
311		 * Get the command register into a known state.
312		 */
313		(void)zc->zc_csr;
314		(void)zc->zc_csr;
315
316		/*
317		 * Do a hardware reset.
318		 */
319		if (channel == 0) {
320			ZS_WRITE(zc, 9, ZSWR9_HARD_RESET);
321			delay(50000);	/* enough ? */
322			ZS_WRITE(zc, 9, 0);
323		}
324
325		/*
326		 * Initialize channel
327		 */
328		zs_loadchannelregs(zc, zs_init_regs);
329	}
330
331	if (machineid & ATARI_TT) {
332		/*
333		 * ininitialise TT-MFP timer C: 307200Hz
334		 * timer C and D share one control register:
335		 *	bits 0-2 control timer D
336		 *	bits 4-6 control timer C
337		 */
338		int cr = MFP2->mf_tcdcr & 7;
339		MFP2->mf_tcdcr = cr;		/* stop timer C  */
340		MFP2->mf_tcdr  = 1;		/* counter 1     */
341		cr |= T_Q004 << 4;		/* divisor 4     */
342		MFP2->mf_tcdcr = cr;		/* start timer C */
343		/*
344		 * enable scc related interrupts
345		 */
346		SCU->vme_mask |= SCU_SCC;
347
348		zs_frequencies = zs_freqs_tt;
349	} else if (machineid & ATARI_FALCON) {
350		zs_frequencies = zs_freqs_falcon;
351	} else if (machineid & ATARI_HADES) {
352		zs_frequencies = zs_freqs_hades;
353	} else {
354		zs_frequencies = zs_freqs_generic;
355	}
356
357	if (intr_establish(36, USER_VEC, 0, (hw_ifun_t)zshard, sc) == NULL)
358		aprint_error_dev(self,
359		    "Can't establish interrupt (Rx chan B)\n");
360	if (intr_establish(32, USER_VEC, 0, (hw_ifun_t)zshard, sc) == NULL)
361		aprint_error_dev(self,
362		    "Can't establish interrupt (Tx empty chan B)\n");
363	if (intr_establish(34, USER_VEC, 0, (hw_ifun_t)zshard, sc) == NULL)
364		aprint_error_dev(self,
365		    "Can't establish interrupt (Ext./Status chan B)\n");
366	if (intr_establish(38, USER_VEC, 0, (hw_ifun_t)zshard, sc) == NULL)
367		aprint_error_dev(self,
368		    "Can't establish interrupt (Special Rx cond. chan B)\n");
369	if (intr_establish(44, USER_VEC, 0, (hw_ifun_t)zshard, sc) == NULL)
370		aprint_error_dev(self,
371		    "Can't establish interrupt (Rx chan A)\n");
372	if (intr_establish(40, USER_VEC, 0, (hw_ifun_t)zshard, sc) == NULL)
373		aprint_error_dev(self,
374		    "Can't establish interrupt (Tx empty chan A)\n");
375	if (intr_establish(42, USER_VEC, 0, (hw_ifun_t)zshard, sc) == NULL)
376		aprint_error_dev(self,
377		    "Can't establish interrupt (Ext./Status chan A)\n");
378	if (intr_establish(46, USER_VEC, 0, (hw_ifun_t)zshard, sc) == NULL)
379		aprint_error_dev(self,
380		    "Can't establish interrupt (Special Rx cond. chan A)\n");
381
382	sc->sc_sicookie = softint_establish(SOFTINT_SERIAL,
383	    (void (*)(void *))zssoft, sc);
384}
385
386/*
387 * Open a zs serial port.
388 */
389static int
390zsopen(dev_t dev, int flags, int mode, struct lwp *l)
391{
392	struct tty *tp;
393	struct zs_chanstate *cs;
394	struct zs_softc *sc;
395	int unit = ZS_UNIT(dev);
396	int zs = unit >> 1;
397	int error, s;
398
399	sc = device_lookup_private(&zs_cd, zs);
400	if (sc == NULL)
401		return ENXIO;
402	cs = sc->sc_cs[unit & 1];
403
404	/*
405	 * When port A (ser02) is selected on the TT, make sure
406	 * the port is enabled.
407	 */
408	if ((machineid & ATARI_TT) && !(unit & 1))
409		ym2149_ser2(1);
410
411	if (cs->cs_rbuf == NULL) {
412		cs->cs_rbuf = kmem_alloc(ZLRB_RING_SIZE * sizeof(int),
413		    KM_SLEEP);
414	}
415
416	tp = cs->cs_ttyp;
417	if (tp == NULL) {
418		cs->cs_ttyp = tp = tty_alloc();
419		tty_attach(tp);
420		tp->t_dev   = dev;
421		tp->t_oproc = zsstart;
422		tp->t_param = zsparam;
423	}
424
425	if (kauth_authorize_device_tty(l->l_cred, KAUTH_DEVICE_TTY_OPEN, tp))
426		return EBUSY;
427
428	s  = spltty();
429
430	/*
431	 * Do the following iff this is a first open.
432	 */
433	if ((tp->t_state & TS_ISOPEN) == 0 && tp->t_wopen == 0) {
434		if (tp->t_ispeed == 0) {
435			tp->t_iflag = TTYDEF_IFLAG;
436			tp->t_oflag = TTYDEF_OFLAG;
437			tp->t_cflag = TTYDEF_CFLAG;
438			tp->t_lflag = TTYDEF_LFLAG;
439			tp->t_ispeed = tp->t_ospeed = TTYDEF_SPEED;
440		}
441		ttychars(tp);
442		ttsetwater(tp);
443
444		(void)zsparam(tp, &tp->t_termios);
445
446		/*
447		 * Turn on DTR.  We must always do this, even if carrier is not
448		 * present, because otherwise we'd have to use TIOCSDTR
449		 * immediately after setting CLOCAL, which applications do not
450		 * expect.  We always assert DTR while the device is open
451		 * unless explicitly requested to deassert it.
452		 */
453		zs_modem(cs, ZSWR5_RTS|ZSWR5_DTR, DMSET);
454		/* May never get a status intr. if DCD already on. -gwr */
455		if (((cs->cs_rr0 = cs->cs_zc->zc_csr) & ZSRR0_DCD) != 0)
456			tp->t_state |= TS_CARR_ON;
457		if (cs->cs_softcar)
458			tp->t_state |= TS_CARR_ON;
459	}
460
461	splx(s);
462
463	error = ttyopen(tp, ZS_DIALOUT(dev), (flags & O_NONBLOCK));
464	if (error)
465		goto bad;
466
467	error = tp->t_linesw->l_open(dev, tp);
468	if (error)
469		goto bad;
470	return 0;
471
472bad:
473	if ((tp->t_state & TS_ISOPEN) == 0 && tp->t_wopen == 0) {
474		/*
475		 * We failed to open the device, and nobody else had it opened.
476		 * Clean up the state as appropriate.
477		 */
478		zs_shutdown(cs);
479	}
480	return error;
481}
482
483/*
484 * Close a zs serial port.
485 */
486static int
487zsclose(dev_t dev, int flags, int mode, struct lwp *l)
488{
489	struct zs_chanstate *cs;
490	struct tty *tp;
491	struct zs_softc *sc;
492	int unit = ZS_UNIT(dev);
493
494	sc = device_lookup_private(&zs_cd, unit >> 1);
495	cs = sc->sc_cs[unit & 1];
496	tp = cs->cs_ttyp;
497
498	tp->t_linesw->l_close(tp, flags);
499	ttyclose(tp);
500
501	if ((tp->t_state & TS_ISOPEN) == 0 && tp->t_wopen == 0) {
502		/*
503		 * Although we got a last close, the device may still be in
504		 * use; e.g. if this was the dialout node, and there are still
505		 * processes waiting for carrier on the non-dialout node.
506		 */
507		zs_shutdown(cs);
508	}
509	return 0;
510}
511
512/*
513 * Read/write zs serial port.
514 */
515static int
516zsread(dev_t dev, struct uio *uio, int flags)
517{
518	struct zs_chanstate *cs;
519	struct zs_softc *sc;
520	struct tty *tp;
521	int unit;
522
523	unit = ZS_UNIT(dev);
524	sc   = device_lookup_private(&zs_cd, unit >> 1);
525	cs   = sc->sc_cs[unit & 1];
526	tp   = cs->cs_ttyp;
527
528	return (*tp->t_linesw->l_read)(tp, uio, flags);
529}
530
531static int
532zswrite(dev_t dev, struct uio *uio, int flags)
533{
534	struct zs_chanstate *cs;
535	struct zs_softc *sc;
536	struct tty *tp;
537	int unit;
538
539	unit = ZS_UNIT(dev);
540	sc   = device_lookup_private(&zs_cd, unit >> 1);
541	cs   = sc->sc_cs[unit & 1];
542	tp   = cs->cs_ttyp;
543
544	return (*tp->t_linesw->l_write)(tp, uio, flags);
545}
546
547static int
548zspoll(dev_t dev, int events, struct lwp *l)
549{
550	struct zs_chanstate *cs;
551	struct zs_softc *sc;
552	struct tty *tp;
553	int unit;
554
555	unit = ZS_UNIT(dev);
556	sc   = device_lookup_private(&zs_cd, unit >> 1);
557	cs   = sc->sc_cs[unit & 1];
558	tp   = cs->cs_ttyp;
559
560	return (*tp->t_linesw->l_poll)(tp, events, l);
561}
562
563static struct tty *
564zstty(dev_t dev)
565{
566	struct zs_chanstate *cs;
567	struct zs_softc *sc;
568	int unit;
569
570	unit = ZS_UNIT(dev);
571	sc   = device_lookup_private(&zs_cd, unit >> 1);
572	cs   = sc->sc_cs[unit & 1];
573	return cs->cs_ttyp;
574}
575
576/*
577 * ZS hardware interrupt.  Scan all ZS channels.  NB: we know here that
578 * channels are kept in (A,B) pairs.
579 *
580 * Do just a little, then get out; set a software interrupt if more
581 * work is needed.
582 *
583 * We deliberately ignore the vectoring Zilog gives us, and match up
584 * only the number of `reset interrupt under service' operations, not
585 * the order.
586 */
587
588int
589zshard(void *arg)
590{
591	struct zs_softc *sc;
592	struct zs_chanstate *cs0, *cs1;
593	struct zschan *zc;
594	int intflags, v, i;
595	uint8_t rr3;
596
597	sc = arg;
598	intflags = 0;
599	cs0 = sc->sc_cs[0];
600	cs1 = sc->sc_cs[1];
601
602	do {
603		intflags &= ~4;
604		rr3 = ZS_READ(cs0->cs_zc, 3);
605		if (rr3 & (ZSRR3_IP_A_RX | ZSRR3_IP_A_TX | ZSRR3_IP_A_STAT)) {
606			intflags |= 4 | 2;
607			zc = cs0->cs_zc;
608			i  = cs0->cs_rbput;
609			if ((rr3 & ZSRR3_IP_A_RX) != 0 &&
610			    (v = zsrint(cs0, zc)) != 0) {
611				cs0->cs_rbuf[i++ & ZLRB_RING_MASK] = v;
612				intflags |= 1;
613			}
614			if ((rr3 & ZSRR3_IP_A_TX) != 0 &&
615			    (v = zsxint(cs0, zc)) != 0) {
616				cs0->cs_rbuf[i++ & ZLRB_RING_MASK] = v;
617				intflags |= 1;
618			}
619			if ((rr3 & ZSRR3_IP_A_STAT) != 0 &&
620			    (v = zssint(cs0, zc)) != 0) {
621				cs0->cs_rbuf[i++ & ZLRB_RING_MASK] = v;
622				intflags |= 1;
623			}
624			cs0->cs_rbput = i;
625		}
626		if (rr3 & (ZSRR3_IP_B_RX | ZSRR3_IP_B_TX | ZSRR3_IP_B_STAT)) {
627			intflags |= 4 | 2;
628			zc = cs1->cs_zc;
629			i  = cs1->cs_rbput;
630			if ((rr3 & ZSRR3_IP_B_RX) != 0 &&
631			    (v = zsrint(cs1, zc)) != 0) {
632				cs1->cs_rbuf[i++ & ZLRB_RING_MASK] = v;
633				intflags |= 1;
634			}
635			if ((rr3 & ZSRR3_IP_B_TX) != 0 &&
636			    (v = zsxint(cs1, zc)) != 0) {
637				cs1->cs_rbuf[i++ & ZLRB_RING_MASK] = v;
638				intflags |= 1;
639			}
640			if ((rr3 & ZSRR3_IP_B_STAT) != 0 &&
641			    (v = zssint(cs1, zc)) != 0) {
642				cs1->cs_rbuf[i++ & ZLRB_RING_MASK] = v;
643				intflags |= 1;
644			}
645			cs1->cs_rbput = i;
646		}
647	} while (intflags & 4);
648
649	if (intflags & 1)
650		softint_schedule(sc->sc_sicookie);
651
652	return intflags & 2;
653}
654
655static int
656zsrint(struct zs_chanstate *cs, struct zschan *zc)
657{
658	int c;
659
660	/*
661	 * First read the status, because read of the received char
662	 * destroy the status of this char.
663	 */
664	c = ZS_READ(zc, 1);
665	c |= (zc->zc_data << 8);
666
667	/* clear receive error & interrupt condition */
668	zc->zc_csr = ZSWR0_RESET_ERRORS;
669	zc->zc_csr = ZSWR0_CLR_INTR;
670
671	return ZRING_MAKE(ZRING_RINT, c);
672}
673
674static int
675zsxint(struct zs_chanstate *cs, struct zschan *zc)
676{
677	int i = cs->cs_tbc;
678
679	if (i == 0) {
680		zc->zc_csr = ZSWR0_RESET_TXINT;
681		zc->zc_csr = ZSWR0_CLR_INTR;
682		return ZRING_MAKE(ZRING_XINT, 0);
683	}
684	cs->cs_tbc = i - 1;
685	zc->zc_data = *cs->cs_tba++;
686	zc->zc_csr = ZSWR0_CLR_INTR;
687	return 0;
688}
689
690static int
691zssint(struct zs_chanstate *cs, struct zschan *zc)
692{
693	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	} else {
712		if (cs->cs_creg[3] & ZSWR3_HFC) {
713			cs->cs_creg[3] &= ~ZSWR3_HFC;
714			ZS_WRITE(zc, 3, cs->cs_creg[3]);
715		}
716	}
717	return ZRING_MAKE(ZRING_SINT, rr0);
718}
719
720/*
721 * Print out a ring or fifo overrun error message.
722 */
723static void
724zsoverrun(int unit, long *ptime, const char *what)
725{
726	time_t cur_sec = time_second;
727
728	if (*ptime != cur_sec) {
729		*ptime = cur_sec;
730		log(LOG_WARNING, "zs%d%c: %s overrun\n", unit >> 1,
731		    (unit & 1) + 'a', what);
732	}
733}
734
735/*
736 * ZS software interrupt.  Scan all channels for deferred interrupts.
737 */
738int
739zssoft(void *arg)
740{
741	struct zs_softc *sc;
742	struct zs_chanstate *cs;
743	struct zschan *zc;
744	struct linesw *line;
745	struct tty *tp;
746	int chan, get, n, c, cc, s;
747	int retval = 0;
748
749	sc = arg;
750	s = spltty();
751	for (chan = 0; chan < 2; chan++) {
752		cs = sc->sc_cs[chan];
753		get = cs->cs_rbget;
754again:
755		n = cs->cs_rbput;	/* atomic			*/
756		if (get == n)		/* nothing more on this line	*/
757			continue;
758		retval = 1;
759		zc     = cs->cs_zc;
760		tp     = cs->cs_ttyp;
761		line   = tp->t_linesw;
762		/*
763		 * Compute the number of interrupts in the receive ring.
764		 * If the count is overlarge, we lost some events, and
765		 * must advance to the first valid one.  It may get
766		 * overwritten if more data are arriving, but this is
767		 * too expensive to check and gains nothing (we already
768		 * lost out; all we can do at this point is trade one
769		 * kind of loss for another).
770		 */
771		n -= get;
772		if (n > ZLRB_RING_SIZE) {
773			zsoverrun(chan, &cs->cs_rotime, "ring");
774			get += n - ZLRB_RING_SIZE;
775			n    = ZLRB_RING_SIZE;
776		}
777		while (--n >= 0) {
778			/* race to keep ahead of incoming interrupts */
779			c = cs->cs_rbuf[get++ & ZLRB_RING_MASK];
780			switch (ZRING_TYPE(c)) {
781
782			case ZRING_RINT:
783				c = ZRING_VALUE(c);
784				if ((c & ZSRR1_DO) != 0)
785					zsoverrun(chan, &cs->cs_fotime, "fifo");
786				cc = c >> 8;
787				if ((c & ZSRR1_FE) != 0)
788					cc |= TTY_FE;
789				if ((c & ZSRR1_PE) != 0)
790					cc |= TTY_PE;
791				line->l_rint(cc, tp);
792				break;
793
794			case ZRING_XINT:
795				/*
796				 * Transmit done: change registers and resume,
797				 * or clear BUSY.
798				 */
799				if (cs->cs_heldchange) {
800					int sps;
801
802					sps = splzs();
803					c = zc->zc_csr;
804					if ((c & ZSRR0_DCD) == 0)
805						cs->cs_preg[3] &= ~ZSWR3_HFC;
806					memcpy((void *)cs->cs_creg,
807					    (void *)cs->cs_preg, 16);
808					zs_loadchannelregs(zc, cs->cs_creg);
809					splx(sps);
810					cs->cs_heldchange = 0;
811					if (cs->cs_heldtbc &&
812					    (tp->t_state & TS_TTSTOP) == 0) {
813						cs->cs_tbc = cs->cs_heldtbc - 1;
814						zc->zc_data = *cs->cs_tba++;
815						goto again;
816					}
817				}
818				tp->t_state &= ~TS_BUSY;
819				if ((tp->t_state & TS_FLUSH) != 0)
820					tp->t_state &= ~TS_FLUSH;
821				else
822					ndflush(&tp->t_outq,
823					    cs->cs_tba - tp->t_outq.c_cf);
824				line->l_start(tp);
825				break;
826
827			case ZRING_SINT:
828				/*
829				 * Status line change.  HFC bit is run in
830				 * hardware interrupt, to avoid locking
831				 * at splzs here.
832				 */
833				c = ZRING_VALUE(c);
834				if (((c ^ cs->cs_rr0) & ZSRR0_DCD) != 0) {
835					cc = (c & ZSRR0_DCD) != 0;
836					if (line->l_modem(tp, cc) == 0)
837						zs_modem(cs,
838						    ZSWR5_RTS | ZSWR5_DTR,
839						    cc ? DMBIS : DMBIC);
840				}
841				cs->cs_rr0 = c;
842				break;
843
844			default:
845				log(LOG_ERR, "zs%d%c: bad ZRING_TYPE (%x)\n",
846				    chan >> 1, (chan & 1) + 'a', c);
847				break;
848			}
849		}
850		cs->cs_rbget = get;
851		goto again;
852	}
853	splx(s);
854	return retval;
855}
856
857static int
858zsioctl(dev_t dev, u_long cmd, void * data, int flag, struct lwp *l)
859{
860	int unit = ZS_UNIT(dev);
861	struct zs_softc *sc = device_lookup_private(&zs_cd, unit >> 1);
862	struct zs_chanstate *cs = sc->sc_cs[unit & 1];
863	struct tty *tp = cs->cs_ttyp;
864	int error, s;
865
866	error = tp->t_linesw->l_ioctl(tp, cmd, data, flag, l);
867	if (error != EPASSTHROUGH)
868		return error;
869
870	error = ttioctl(tp, cmd, data, flag, l);
871	if (error !=EPASSTHROUGH)
872		return error;
873
874	switch (cmd) {
875	case TIOCSBRK:
876		s = splzs();
877		cs->cs_preg[5] |= ZSWR5_BREAK;
878		cs->cs_creg[5] |= ZSWR5_BREAK;
879		ZS_WRITE(cs->cs_zc, 5, cs->cs_creg[5]);
880		splx(s);
881		break;
882	case TIOCCBRK:
883		s = splzs();
884		cs->cs_preg[5] &= ~ZSWR5_BREAK;
885		cs->cs_creg[5] &= ~ZSWR5_BREAK;
886		ZS_WRITE(cs->cs_zc, 5, cs->cs_creg[5]);
887		splx(s);
888		break;
889	case TIOCGFLAGS: {
890		int bits = 0;
891
892		if (cs->cs_softcar)
893			bits |= TIOCFLAG_SOFTCAR;
894		if ((cs->cs_creg[15] & ZSWR15_DCD_IE) != 0)
895			bits |= TIOCFLAG_CLOCAL;
896		if ((cs->cs_creg[3] & ZSWR3_HFC) != 0)
897			bits |= TIOCFLAG_CRTSCTS;
898		*(int *)data = bits;
899		break;
900	}
901	case TIOCSFLAGS: {
902		int userbits = 0;
903
904		error = kauth_authorize_device_tty(l->l_cred,
905		    KAUTH_DEVICE_TTY_PRIVSET, tp);
906		if (error != 0)
907			return EPERM;
908
909		userbits = *(int *)data;
910
911		/*
912		 * can have `local' or `softcar', and `rtscts' or `mdmbuf'
913		 # defaulting to software flow control.
914		 */
915		if ((userbits & TIOCFLAG_SOFTCAR) != 0 &&
916		    (userbits & TIOCFLAG_CLOCAL) != 0)
917			return EINVAL;
918		if ((userbits & TIOCFLAG_MDMBUF) != 0)
919			/* don't support this (yet?) */
920			return ENODEV;
921
922		s = splzs();
923		if ((userbits & TIOCFLAG_SOFTCAR) != 0) {
924			cs->cs_softcar = 1;	/* turn on softcar */
925			cs->cs_preg[15] &= ~ZSWR15_DCD_IE; /* turn off dcd */
926			cs->cs_creg[15] &= ~ZSWR15_DCD_IE;
927			ZS_WRITE(cs->cs_zc, 15, cs->cs_creg[15]);
928		} else if ((userbits & TIOCFLAG_CLOCAL) != 0) {
929			cs->cs_softcar = 0;	/* turn off softcar */
930			cs->cs_preg[15] |= ZSWR15_DCD_IE; /* turn on dcd */
931			cs->cs_creg[15] |= ZSWR15_DCD_IE;
932			ZS_WRITE(cs->cs_zc, 15, cs->cs_creg[15]);
933			tp->t_termios.c_cflag |= CLOCAL;
934		}
935		if ((userbits & TIOCFLAG_CRTSCTS) != 0) {
936			cs->cs_preg[15] |= ZSWR15_CTS_IE;
937			cs->cs_creg[15] |= ZSWR15_CTS_IE;
938			ZS_WRITE(cs->cs_zc, 15, cs->cs_creg[15]);
939			cs->cs_preg[3] |= ZSWR3_HFC;
940			cs->cs_creg[3] |= ZSWR3_HFC;
941			ZS_WRITE(cs->cs_zc, 3, cs->cs_creg[3]);
942			tp->t_termios.c_cflag |= CRTSCTS;
943		} else {
944			/* no mdmbuf, so we must want software flow control */
945			cs->cs_preg[15] &= ~ZSWR15_CTS_IE;
946			cs->cs_creg[15] &= ~ZSWR15_CTS_IE;
947			ZS_WRITE(cs->cs_zc, 15, cs->cs_creg[15]);
948			cs->cs_preg[3] &= ~ZSWR3_HFC;
949			cs->cs_creg[3] &= ~ZSWR3_HFC;
950			ZS_WRITE(cs->cs_zc, 3, cs->cs_creg[3]);
951			tp->t_termios.c_cflag &= ~CRTSCTS;
952		}
953		splx(s);
954		break;
955	}
956	case TIOCSDTR:
957		zs_modem(cs, ZSWR5_DTR, DMBIS);
958		break;
959	case TIOCCDTR:
960		zs_modem(cs, ZSWR5_DTR, DMBIC);
961		break;
962	case TIOCMGET:
963		zs_modem(cs, 0, DMGET);
964		break;
965	case TIOCMSET:
966	case TIOCMBIS:
967	case TIOCMBIC:
968	default:
969		return EPASSTHROUGH;
970	}
971	return 0;
972}
973
974/*
975 * Start or restart transmission.
976 */
977static void
978zsstart(struct tty *tp)
979{
980	struct zs_chanstate *cs;
981	int s, nch;
982	int unit = ZS_UNIT(tp->t_dev);
983	struct zs_softc *sc = device_lookup_private(&zs_cd, unit >> 1);
984
985	cs = sc->sc_cs[unit & 1];
986	s  = spltty();
987
988	/*
989	 * If currently active or delaying, no need to do anything.
990	 */
991	if ((tp->t_state & (TS_TIMEOUT | TS_BUSY | TS_TTSTOP)) != 0)
992		goto out;
993
994	/*
995	 * If there are sleepers, and output has drained below low
996	 * water mark, awaken.
997	 */
998	ttypull(tp);
999
1000	nch = ndqb(&tp->t_outq, 0);	/* XXX */
1001	if (nch) {
1002		char *p = tp->t_outq.c_cf;
1003
1004		/* mark busy, enable tx done interrupts, & send first byte */
1005		tp->t_state |= TS_BUSY;
1006		(void)splzs();
1007		cs->cs_preg[1] |= ZSWR1_TIE;
1008		cs->cs_creg[1] |= ZSWR1_TIE;
1009		ZS_WRITE(cs->cs_zc, 1, cs->cs_creg[1]);
1010		cs->cs_zc->zc_data = *p;
1011		cs->cs_tba = p + 1;
1012		cs->cs_tbc = nch - 1;
1013	} else {
1014		/*
1015		 * Nothing to send, turn off transmit done interrupts.
1016		 * This is useful if something is doing polled output.
1017		 */
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	}
1023out:
1024	splx(s);
1025}
1026
1027/*
1028 * Stop output, e.g., for ^S or output flush.
1029 */
1030static void
1031zsstop(struct tty *tp, int flag)
1032{
1033	struct zs_chanstate *cs;
1034	int s, unit = ZS_UNIT(tp->t_dev);
1035	struct zs_softc *sc = device_lookup_private(&zs_cd, unit >> 1);
1036
1037	cs = sc->sc_cs[unit & 1];
1038	s  = splzs();
1039	if ((tp->t_state & TS_BUSY) != 0) {
1040		/*
1041		 * Device is transmitting; must stop it.
1042		 */
1043		cs->cs_tbc = 0;
1044		if ((tp->t_state & TS_TTSTOP) == 0)
1045			tp->t_state |= TS_FLUSH;
1046	}
1047	splx(s);
1048}
1049
1050static void
1051zs_shutdown(struct zs_chanstate *cs)
1052{
1053	struct tty *tp = cs->cs_ttyp;
1054	int s;
1055
1056	s = splzs();
1057
1058	/*
1059	 * Hang up if necessary.  Wait a bit, so the other side has time to
1060	 * notice even if we immediately open the port again.
1061	 */
1062	if ((tp->t_cflag & HUPCL) != 0) {
1063		zs_modem(cs, 0, DMSET);
1064		(void)tsleep((void *)cs, TTIPRI, ttclos, hz);
1065	}
1066
1067	/* Clear any break condition set with TIOCSBRK. */
1068	if ((cs->cs_creg[5] & ZSWR5_BREAK) != 0) {
1069		cs->cs_preg[5] &= ~ZSWR5_BREAK;
1070		cs->cs_creg[5] &= ~ZSWR5_BREAK;
1071		ZS_WRITE(cs->cs_zc, 5, cs->cs_creg[5]);
1072	}
1073
1074	/*
1075	 * Drop all lines and cancel interrupts
1076	 */
1077	zs_loadchannelregs(cs->cs_zc, zs_init_regs);
1078	splx(s);
1079}
1080
1081/*
1082 * Set ZS tty parameters from termios.
1083 *
1084 * This routine makes use of the fact that only registers
1085 * 1, 3, 4, 5, 9, 10, 11, 12, 13, 14, and 15 are written.
1086 */
1087static int
1088zsparam(struct tty *tp, struct termios *t)
1089{
1090	int unit = ZS_UNIT(tp->t_dev);
1091	struct zs_softc *sc = device_lookup_private(&zs_cd, unit >> 1);
1092	struct zs_chanstate *cs = sc->sc_cs[unit & 1];
1093	int cdiv = 0;	/* XXX gcc4 -Wuninitialized */
1094	int clkm = 0;	/* XXX gcc4 -Wuninitialized */
1095	int brgm = 0;	/* XXX gcc4 -Wuninitialized */
1096	int tcon = 0;	/* XXX gcc4 -Wuninitialized */
1097	int tmp, tmp5, cflag, s;
1098
1099	tmp  = t->c_ospeed;
1100	tmp5 = t->c_ispeed;
1101	if (tmp < 0 || (tmp5 && tmp5 != tmp))
1102		return EINVAL;
1103	if (tmp == 0) {
1104		/* stty 0 => drop DTR and RTS */
1105		zs_modem(cs, 0, DMSET);
1106		return 0;
1107	}
1108	tmp = zsbaudrate(unit, tmp, &cdiv, &clkm, &brgm, &tcon);
1109	if (tmp < 0)
1110		return EINVAL;
1111	tp->t_ispeed = tp->t_ospeed = tmp;
1112
1113	cflag = tp->t_cflag = t->c_cflag;
1114	if ((cflag & CSTOPB) != 0)
1115		cdiv |= ZSWR4_TWOSB;
1116	else
1117		cdiv |= ZSWR4_ONESB;
1118	if ((cflag & PARODD) == 0)
1119		cdiv |= ZSWR4_EVENP;
1120	if ((cflag & PARENB) != 0)
1121		cdiv |= ZSWR4_PARENB;
1122
1123	switch (cflag & CSIZE) {
1124	case CS5:
1125		tmp  = ZSWR3_RX_5;
1126		tmp5 = ZSWR5_TX_5;
1127		break;
1128	case CS6:
1129		tmp  = ZSWR3_RX_6;
1130		tmp5 = ZSWR5_TX_6;
1131		break;
1132	case CS7:
1133		tmp  = ZSWR3_RX_7;
1134		tmp5 = ZSWR5_TX_7;
1135		break;
1136	case CS8:
1137	default:
1138		tmp  = ZSWR3_RX_8;
1139		tmp5 = ZSWR5_TX_8;
1140		break;
1141	}
1142	tmp  |= ZSWR3_RX_ENABLE;
1143	tmp5 |= ZSWR5_TX_ENABLE | ZSWR5_DTR | ZSWR5_RTS;
1144
1145	/*
1146	 * Block interrupts so that state will not
1147	 * be altered until we are done setting it up.
1148	 */
1149	s = splzs();
1150	cs->cs_preg[4]  = cdiv;
1151	cs->cs_preg[11] = clkm;
1152	cs->cs_preg[12] = tcon;
1153	cs->cs_preg[13] = tcon >> 8;
1154	cs->cs_preg[14] = brgm;
1155	cs->cs_preg[1]  = ZSWR1_RIE | ZSWR1_TIE | ZSWR1_SIE;
1156	cs->cs_preg[9]  = ZSWR9_MASTER_IE | ZSWR9_VECTOR_INCL_STAT;
1157	cs->cs_preg[10] = ZSWR10_NRZ;
1158	cs->cs_preg[15] = ZSWR15_BREAK_IE | ZSWR15_DCD_IE;
1159
1160	/*
1161	 * Output hardware flow control on the chip is horrendous: if
1162	 * carrier detect drops, the receiver is disabled.  Hence we
1163	 * can only do this when the carrier is on.
1164	 */
1165	if ((cflag & CCTS_OFLOW) != 0 &&
1166	    (cs->cs_zc->zc_csr & ZSRR0_DCD) != 0)
1167		tmp |= ZSWR3_HFC;
1168	cs->cs_preg[3] = tmp;
1169	cs->cs_preg[5] = tmp5;
1170
1171	/*
1172	 * If nothing is being transmitted, set up new current values,
1173	 * else mark them as pending.
1174	 */
1175	if (cs->cs_heldchange == 0) {
1176		if ((cs->cs_ttyp->t_state & TS_BUSY) != 0) {
1177			cs->cs_heldtbc = cs->cs_tbc;
1178			cs->cs_tbc = 0;
1179			cs->cs_heldchange = 1;
1180		} else {
1181			memcpy((void *)cs->cs_creg, (void *)cs->cs_preg, 16);
1182			zs_loadchannelregs(cs->cs_zc, cs->cs_creg);
1183		}
1184	}
1185	splx(s);
1186	return 0;
1187}
1188
1189/*
1190 * search for the best matching baudrate
1191 */
1192static int
1193zsbaudrate(int unit, int wanted, int *divisor, int *clockmode, int *brgenmode,
1194    int *timeconst)
1195{
1196	int bestdiff, bestbps, source;
1197
1198	bestdiff = bestbps = 0;
1199	unit = (unit & 1) << 2;
1200	for (source = 0; source < 4; ++source) {
1201		u_long freq = zs_frequencies[unit + source];
1202		int diff, bps, div, clkm, brgm, tcon;
1203
1204		bps = div = clkm = brgm = tcon = 0;
1205		switch (source) {
1206		case 0:	/* BRgen, PCLK */
1207			brgm = ZSWR14_BAUD_ENA|ZSWR14_BAUD_FROM_PCLK;
1208			break;
1209		case 1:	/* BRgen, RTxC */
1210			brgm = ZSWR14_BAUD_ENA;
1211			break;
1212		case 2: /* RTxC */
1213			clkm = ZSWR11_RXCLK_RTXC|ZSWR11_TXCLK_RTXC;
1214			break;
1215		case 3: /* TRxC */
1216			clkm = ZSWR11_RXCLK_TRXC|ZSWR11_TXCLK_TRXC;
1217			break;
1218		}
1219		switch (source) {
1220		case 0:
1221		case 1:
1222			div  = ZSWR4_CLK_X16;
1223			clkm = ZSWR11_RXCLK_BAUD|ZSWR11_TXCLK_BAUD;
1224			tcon = BPS_TO_TCONST(freq, wanted);
1225			if (tcon < 0)
1226				tcon = 0;
1227			bps  = TCONST_TO_BPS(freq, tcon);
1228			break;
1229		case 2:
1230		case 3:
1231		    {
1232			int b1 = freq / 16, d1 = abs(b1 - wanted);
1233			int b2 = freq / 32, d2 = abs(b2 - wanted);
1234			int b3 = freq / 64, d3 = abs(b3 - wanted);
1235
1236			if (d1 < d2 && d1 < d3) {
1237				div = ZSWR4_CLK_X16;
1238				bps = b1;
1239			} else if (d2 < d3 && d2 < d1) {
1240				div = ZSWR4_CLK_X32;
1241				bps = b2;
1242			} else {
1243				div = ZSWR4_CLK_X64;
1244				bps = b3;
1245			}
1246			brgm = tcon = 0;
1247			break;
1248		    }
1249		}
1250		diff = abs(bps - wanted);
1251		if (!source || diff < bestdiff) {
1252			*divisor   = div;
1253			*clockmode = clkm;
1254			*brgenmode = brgm;
1255			*timeconst = tcon;
1256			bestbps    = bps;
1257			bestdiff   = diff;
1258			if (diff == 0)
1259				break;
1260		}
1261	}
1262	/* Allow deviations upto 5% */
1263	if (20 * bestdiff > wanted)
1264		return -1;
1265	return bestbps;
1266}
1267
1268/*
1269 * Raise or lower modem control (DTR/RTS) signals.  If a character is
1270 * in transmission, the change is deferred.
1271 */
1272static int
1273zs_modem(struct zs_chanstate *cs, int bits, int how)
1274{
1275	int s, mbits;
1276
1277	bits  &= ZSWR5_DTR | ZSWR5_RTS;
1278
1279	s = splzs();
1280	mbits  = cs->cs_preg[5] &  (ZSWR5_DTR | ZSWR5_RTS);
1281
1282	switch (how) {
1283	case DMSET:
1284		mbits  = bits;
1285		break;
1286	case DMBIS:
1287		mbits |= bits;
1288		break;
1289	case DMBIC:
1290		mbits &= ~bits;
1291		break;
1292	case DMGET:
1293		splx(s);
1294		return mbits;
1295	}
1296
1297	cs->cs_preg[5] = (cs->cs_preg[5] & ~(ZSWR5_DTR | ZSWR5_RTS)) | mbits;
1298	if (cs->cs_heldchange == 0) {
1299		if ((cs->cs_ttyp->t_state & TS_BUSY) != 0) {
1300			cs->cs_heldtbc = cs->cs_tbc;
1301			cs->cs_tbc = 0;
1302			cs->cs_heldchange = 1;
1303		} else {
1304			ZS_WRITE(cs->cs_zc, 5, cs->cs_creg[5]);
1305		}
1306	}
1307	splx(s);
1308	return 0;
1309}
1310
1311/*
1312 * Write the given register set to the given zs channel in the proper order.
1313 * The channel must not be transmitting at the time.  The receiver will
1314 * be disabled for the time it takes to write all the registers.
1315 */
1316static void
1317zs_loadchannelregs(struct zschan *zc, uint8_t *reg)
1318{
1319	int i;
1320
1321	zc->zc_csr = ZSM_RESET_ERR;	/* reset error condition */
1322	i = zc->zc_data;		/* drain fifo */
1323	i = zc->zc_data;
1324	i = zc->zc_data;
1325	ZS_WRITE(zc,  4, reg[4]);
1326	ZS_WRITE(zc, 10, reg[10]);
1327	ZS_WRITE(zc,  3, reg[3] & ~ZSWR3_RX_ENABLE);
1328	ZS_WRITE(zc,  5, reg[5] & ~ZSWR5_TX_ENABLE);
1329	ZS_WRITE(zc,  1, reg[1]);
1330	ZS_WRITE(zc,  9, reg[9]);
1331	ZS_WRITE(zc, 11, reg[11]);
1332	ZS_WRITE(zc, 12, reg[12]);
1333	ZS_WRITE(zc, 13, reg[13]);
1334	ZS_WRITE(zc, 14, reg[14]);
1335	ZS_WRITE(zc, 15, reg[15]);
1336	ZS_WRITE(zc,  3, reg[3]);
1337	ZS_WRITE(zc,  5, reg[5]);
1338	__USE(i);
1339}
1340#endif /* NZS > 1 */
1341