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ms.c revision 1.19
      1 /*	$NetBSD: ms.c,v 1.19 2003/09/21 19:16:53 jdolecek 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  * All advertising materials mentioning features or use of this software
     12  * must display the following acknowledgement:
     13  *	This product includes software developed by the University of
     14  *	California, Lawrence Berkeley Laboratory.
     15  *
     16  * Redistribution and use in source and binary forms, with or without
     17  * modification, are permitted provided that the following conditions
     18  * are met:
     19  * 1. Redistributions of source code must retain the above copyright
     20  *    notice, this list of conditions and the following disclaimer.
     21  * 2. Redistributions in binary form must reproduce the above copyright
     22  *    notice, this list of conditions and the following disclaimer in the
     23  *    documentation and/or other materials provided with the distribution.
     24  * 3. Neither the name of the University nor the names of its contributors
     25  *    may be used to endorse or promote products derived from this software
     26  *    without specific prior written permission.
     27  *
     28  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     29  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     30  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     31  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     32  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     33  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     34  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     35  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     36  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     37  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     38  * SUCH DAMAGE.
     39  *
     40  *	@(#)ms.c	8.1 (Berkeley) 6/11/93
     41  */
     42 
     43 /*
     44  * X68k mouse driver.
     45  */
     46 
     47 #include <sys/cdefs.h>
     48 __KERNEL_RCSID(0, "$NetBSD: ms.c,v 1.19 2003/09/21 19:16:53 jdolecek Exp $");
     49 
     50 #include <sys/param.h>
     51 #include <sys/conf.h>
     52 #include <sys/ioctl.h>
     53 #include <sys/kernel.h>
     54 #include <sys/proc.h>
     55 #include <sys/syslog.h>
     56 #include <sys/systm.h>
     57 #include <sys/tty.h>
     58 #include <sys/device.h>
     59 #include <sys/signalvar.h>
     60 
     61 #include <dev/ic/z8530reg.h>
     62 #include <machine/z8530var.h>
     63 
     64 #include <arch/x68k/dev/event_var.h>
     65 #include <machine/vuid_event.h>
     66 #include <arch/x68k/dev/mfp.h>
     67 
     68 #include "locators.h"
     69 
     70 /*
     71  * How many input characters we can buffer.
     72  * The port-specific var.h may override this.
     73  * Note: must be a power of two!
     74  */
     75 #define	MS_RX_RING_SIZE	256
     76 #define MS_RX_RING_MASK (MS_RX_RING_SIZE-1)
     77 /*
     78  * Output buffer.  Only need a few chars.
     79  */
     80 #define	MS_TX_RING_SIZE	16
     81 #define MS_TX_RING_MASK (MS_TX_RING_SIZE-1)
     82 /*
     83  * Mouse serial line is fixed at 4800 bps.
     84  */
     85 #define MS_BPS 4800
     86 
     87 /*
     88  * Mouse state.  A SHARP X1/X680x0 mouse is a fairly simple device,
     89  * producing three-byte blobs of the form:
     90  *
     91  *	b dx dy
     92  *
     93  * where b is the button state, encoded as 0x80|(buttons)---there are
     94  * two buttons (2=left, 1=right)---and dx,dy are X and Y delta values.
     95  *
     96  * It needs a trigger for the transmission.  When zs RTS negated, the
     97  * mouse begins the sequence.  RTS assertion has no effect.
     98  */
     99 struct ms_softc {
    100 	struct	device ms_dev;		/* required first: base device */
    101 	struct	zs_chanstate *ms_cs;
    102 
    103 	struct callout ms_modem_ch;
    104 
    105 	/* Flags to communicate with ms_softintr() */
    106 	volatile int ms_intr_flags;
    107 #define	INTR_RX_OVERRUN 1
    108 #define INTR_TX_EMPTY   2
    109 #define INTR_ST_CHECK   4
    110 
    111 	/*
    112 	 * The receive ring buffer.
    113 	 */
    114 	u_int	ms_rbget;	/* ring buffer `get' index */
    115 	volatile u_int	ms_rbput;	/* ring buffer `put' index */
    116 	u_short	ms_rbuf[MS_RX_RING_SIZE]; /* rr1, data pairs */
    117 
    118 	/*
    119 	 * State of input translator
    120 	 */
    121 	short	ms_byteno;		/* input byte number, for decode */
    122 	char	ms_mb;			/* mouse button state */
    123 	char	ms_ub;			/* user button state */
    124 	int	ms_dx;			/* delta-x */
    125 	int	ms_dy;			/* delta-y */
    126 	int	ms_rts;			/* MSCTRL */
    127 	int	ms_nodata;
    128 
    129 	/*
    130 	 * State of upper interface.
    131 	 */
    132 	volatile int ms_ready;		/* event queue is ready */
    133 	struct	evvar ms_events;	/* event queue state */
    134 } ms_softc;
    135 
    136 static int ms_match __P((struct device*, struct cfdata*, void*));
    137 static void ms_attach __P((struct device*, struct device*, void*));
    138 static void ms_trigger __P((struct zs_chanstate*, int));
    139 void ms_modem __P((void *));
    140 
    141 CFATTACH_DECL(ms, sizeof(struct ms_softc),
    142     ms_match, ms_attach, NULL, NULL);
    143 
    144 extern struct zsops zsops_ms;
    145 extern struct cfdriver ms_cd;
    146 
    147 dev_type_open(msopen);
    148 dev_type_close(msclose);
    149 dev_type_read(msread);
    150 dev_type_ioctl(msioctl);
    151 dev_type_poll(mspoll);
    152 dev_type_kqfilter(mskqfilter);
    153 
    154 const struct cdevsw ms_cdevsw ={
    155 	msopen, msclose, msread, nowrite, msioctl,
    156 	nostop, notty, mspoll, nommap, mskqfilter,
    157 };
    158 
    159 /*
    160  * ms_match: how is this zs channel configured?
    161  */
    162 int
    163 ms_match(parent, cf, aux)
    164 	struct device *parent;
    165 	struct cfdata *cf;
    166 	void   *aux;
    167 {
    168 	struct zsc_attach_args *args = aux;
    169 	struct zsc_softc *zsc = (void*) parent;
    170 
    171 	/* Exact match required for the mouse. */
    172 	if (cf->cf_loc[ZSCCF_CHANNEL] != args->channel)
    173 		return 0;
    174 	if (args->channel != 1)
    175 		return 0;
    176 	if (&zsc->zsc_addr->zs_chan_b != (struct zschan *) ZSMS_PHYSADDR)
    177 		return 0;
    178 
    179 	return 2;
    180 }
    181 
    182 void
    183 ms_attach(parent, self, aux)
    184 	struct device *parent, *self;
    185 	void   *aux;
    186 
    187 {
    188 	struct zsc_softc *zsc = (void *) parent;
    189 	struct ms_softc *ms = (void *) self;
    190 	struct zs_chanstate *cs;
    191 	struct cfdata *cf;
    192 	int reset, s;
    193 
    194 	callout_init(&ms->ms_modem_ch);
    195 
    196 	cf = ms->ms_dev.dv_cfdata;
    197 	cs = zsc->zsc_cs[1];
    198 	cs->cs_private = ms;
    199 	cs->cs_ops = &zsops_ms;
    200 	ms->ms_cs = cs;
    201 
    202 	/* Initialize the speed, etc. */
    203 	s = splzs();
    204 	/* May need reset... */
    205 	reset = ZSWR9_B_RESET;
    206 	zs_write_reg(cs, 9, reset);
    207 	/* We don't care about status or tx interrupts. */
    208 	cs->cs_preg[1] = ZSWR1_RIE;
    209 	cs->cs_preg[4] = ZSWR4_CLK_X16 | ZSWR4_TWOSB;
    210 	(void) zs_set_speed(cs, MS_BPS);
    211 	zs_loadchannelregs(cs);
    212 	splx(s);
    213 
    214 	/* Initialize translator. */
    215 	ms->ms_ready = 0;
    216 
    217 	printf ("\n");
    218 }
    219 
    220 /****************************************************************
    221  *  Entry points for /dev/mouse
    222  *  (open,close,read,write,...)
    223  ****************************************************************/
    224 
    225 int
    226 msopen(dev, flags, mode, p)
    227 	dev_t dev;
    228 	int flags, mode;
    229 	struct proc *p;
    230 {
    231 	struct ms_softc *ms;
    232 	int unit;
    233 
    234 	unit = minor(dev);
    235 	if (unit >= ms_cd.cd_ndevs)
    236 		return (ENXIO);
    237 	ms = ms_cd.cd_devs[unit];
    238 	if (ms == NULL)
    239 		return (ENXIO);
    240 
    241 	/* This is an exclusive open device. */
    242 	if (ms->ms_events.ev_io)
    243 		return (EBUSY);
    244 	ms->ms_events.ev_io = p;
    245 	ev_init(&ms->ms_events);	/* may cause sleep */
    246 
    247 	ms->ms_ready = 1;		/* start accepting events */
    248 	ms->ms_rts = 1;
    249 	ms->ms_byteno = -1;
    250 	ms->ms_nodata = 0;
    251 
    252 	/* start sequencer */
    253 	ms_modem(ms);
    254 
    255 	return (0);
    256 }
    257 
    258 int
    259 msclose(dev, flags, mode, p)
    260 	dev_t dev;
    261 	int flags, mode;
    262 	struct proc *p;
    263 {
    264 	struct ms_softc *ms;
    265 
    266 	ms = ms_cd.cd_devs[minor(dev)];
    267 	ms->ms_ready = 0;		/* stop accepting events */
    268 	callout_stop(&ms->ms_modem_ch);
    269 	ev_fini(&ms->ms_events);
    270 
    271 	ms->ms_events.ev_io = NULL;
    272 	return (0);
    273 }
    274 
    275 int
    276 msread(dev, uio, flags)
    277 	dev_t dev;
    278 	struct uio *uio;
    279 	int flags;
    280 {
    281 	struct ms_softc *ms;
    282 
    283 	ms = ms_cd.cd_devs[minor(dev)];
    284 	return (ev_read(&ms->ms_events, uio, flags));
    285 }
    286 
    287 int
    288 msioctl(dev, cmd, data, flag, p)
    289 	dev_t dev;
    290 	u_long cmd;
    291 	register caddr_t data;
    292 	int flag;
    293 	struct proc *p;
    294 {
    295 	struct ms_softc *ms;
    296 
    297 	ms = ms_cd.cd_devs[minor(dev)];
    298 
    299 	switch (cmd) {
    300 
    301 	case FIONBIO:		/* we will remove this someday (soon???) */
    302 		return (0);
    303 
    304 	case FIOASYNC:
    305 		ms->ms_events.ev_async = *(int *)data != 0;
    306 		return (0);
    307 
    308 	case FIOSETOWN:
    309 		if (-*(int *)data != ms->ms_events.ev_io->p_pgid
    310 		    && *(int *)data != ms->ms_events.ev_io->p_pid)
    311 			return (EPERM);
    312 		return(0);
    313 
    314 	case TIOCSPGRP:
    315 		if (*(int *)data != ms->ms_events.ev_io->p_pgid)
    316 			return (EPERM);
    317 		return (0);
    318 
    319 	case VUIDGFORMAT:
    320 		/* we only do firm_events */
    321 		*(int *)data = VUID_FIRM_EVENT;
    322 		return (0);
    323 
    324 	case VUIDSFORMAT:
    325 		if (*(int *)data != VUID_FIRM_EVENT)
    326 			return (EINVAL);
    327 		return (0);
    328 	}
    329 	return (ENOTTY);
    330 }
    331 
    332 int
    333 mspoll(dev, events, p)
    334 	dev_t dev;
    335 	int events;
    336 	struct proc *p;
    337 {
    338 	struct ms_softc *ms;
    339 
    340 	ms = ms_cd.cd_devs[minor(dev)];
    341 	return (ev_poll(&ms->ms_events, events, p));
    342 }
    343 
    344 int
    345 mskqfilter(dev_t dev, struct knote *kn)
    346 {
    347 	struct ms_softc *ms;
    348 
    349 	ms = ms_cd.cd_devs[minor(dev)];
    350 	return (ev_kqfilter(&ms->ms_events, kn));
    351 }
    352 
    353 /****************************************************************
    354  * Middle layer (translator)
    355  ****************************************************************/
    356 
    357 static void ms_input __P((struct ms_softc *, int c));
    358 
    359 
    360 /*
    361  * Called by our ms_softint() routine on input.
    362  */
    363 static void
    364 ms_input(ms, c)
    365 	register struct ms_softc *ms;
    366 	register int c;
    367 {
    368 	register struct firm_event *fe;
    369 	register int mb, ub, d, get, put, any;
    370 	static const char to_one[] = { 1, 2, 3 };
    371 	static const int to_id[] = { MS_LEFT, MS_RIGHT, MS_MIDDLE };
    372 
    373 	/*
    374 	 * Discard input if not ready.  Drop sync on parity or framing
    375 	 * error; gain sync on button byte.
    376 	 */
    377 	if (ms->ms_ready == 0)
    378 		return;
    379 
    380 	ms->ms_nodata = 0;
    381 	/*
    382 	 * Run the decode loop, adding to the current information.
    383 	 * We add, rather than replace, deltas, so that if the event queue
    384 	 * fills, we accumulate data for when it opens up again.
    385 	 */
    386 	switch (ms->ms_byteno) {
    387 
    388 	case -1:
    389 		return;
    390 
    391 	case 0:
    392 		/* buttons */
    393 		ms->ms_byteno = 1;
    394 		ms->ms_mb = c & 0x3;
    395 		return;
    396 
    397 	case 1:
    398 		/* delta-x */
    399 		ms->ms_byteno = 2;
    400 		ms->ms_dx += (char)c;
    401 		return;
    402 
    403 	case 2:
    404 		/* delta-y */
    405 		ms->ms_byteno = -1;
    406 		ms->ms_dy += (char)c;
    407 		break;
    408 
    409 	default:
    410 		panic("ms_input");
    411 		/* NOTREACHED */
    412 	}
    413 
    414 	/*
    415 	 * We have at least one event (mouse button, delta-X, or
    416 	 * delta-Y; possibly all three, and possibly three separate
    417 	 * button events).  Deliver these events until we are out
    418 	 * of changes or out of room.  As events get delivered,
    419 	 * mark them `unchanged'.
    420 	 */
    421 	any = 0;
    422 	get = ms->ms_events.ev_get;
    423 	put = ms->ms_events.ev_put;
    424 	fe = &ms->ms_events.ev_q[put];
    425 
    426 	/* NEXT prepares to put the next event, backing off if necessary */
    427 #define	NEXT \
    428 	if ((++put) % EV_QSIZE == get) { \
    429 		put--; \
    430 		goto out; \
    431 	}
    432 	/* ADVANCE completes the `put' of the event */
    433 #define	ADVANCE \
    434 	fe++; \
    435 	if (put >= EV_QSIZE) { \
    436 		put = 0; \
    437 		fe = &ms->ms_events.ev_q[0]; \
    438 	} \
    439 
    440 	mb = ms->ms_mb;
    441 	ub = ms->ms_ub;
    442 	while ((d = mb ^ ub) != 0) {
    443 		/*
    444 		 * Mouse button change.  Convert up to three changes
    445 		 * to the `first' change, and drop it into the event queue.
    446 		 */
    447 		NEXT;
    448 		d = to_one[d - 1];		/* from 1..7 to {1,2,4} */
    449 		fe->id = to_id[d - 1];		/* from {1,2,4} to ID */
    450 		fe->value = mb & d ? VKEY_DOWN : VKEY_UP;
    451 		fe->time = time;
    452 		ADVANCE;
    453 		ub ^= d;
    454 		any++;
    455 	}
    456 	if (ms->ms_dx) {
    457 		NEXT;
    458 		fe->id = LOC_X_DELTA;
    459 		fe->value = ms->ms_dx;
    460 		fe->time = time;
    461 		ADVANCE;
    462 		ms->ms_dx = 0;
    463 		any++;
    464 	}
    465 	if (ms->ms_dy) {
    466 		NEXT;
    467 		fe->id = LOC_Y_DELTA;
    468 		fe->value = -ms->ms_dy;	/* XXX? */
    469 		fe->time = time;
    470 		ADVANCE;
    471 		ms->ms_dy = 0;
    472 		any++;
    473 	}
    474 out:
    475 	if (any) {
    476 		ms->ms_ub = ub;
    477 		ms->ms_events.ev_put = put;
    478 		EV_WAKEUP(&ms->ms_events);
    479 	}
    480 }
    481 
    482 /****************************************************************
    483  * Interface to the lower layer (zscc)
    484  ****************************************************************/
    485 
    486 static void ms_rxint __P((struct zs_chanstate *));
    487 static void ms_stint __P((struct zs_chanstate *, int));
    488 static void ms_txint __P((struct zs_chanstate *));
    489 static void ms_softint __P((struct zs_chanstate *));
    490 
    491 static void
    492 ms_rxint(cs)
    493 	register struct zs_chanstate *cs;
    494 {
    495 	register struct ms_softc *ms;
    496 	register int put, put_next;
    497 	register u_char c, rr1;
    498 
    499 	ms = cs->cs_private;
    500 	put = ms->ms_rbput;
    501 
    502 	/*
    503 	 * First read the status, because reading the received char
    504 	 * destroys the status of this char.
    505 	 */
    506 	rr1 = zs_read_reg(cs, 1);
    507 	c = zs_read_data(cs);
    508 
    509 	if (rr1 & (ZSRR1_FE | ZSRR1_DO | ZSRR1_PE)) {
    510 		/* Clear the receive error. */
    511 		zs_write_csr(cs, ZSWR0_RESET_ERRORS);
    512 	}
    513 
    514 	ms->ms_rbuf[put] = (c << 8) | rr1;
    515 	put_next = (put + 1) & MS_RX_RING_MASK;
    516 
    517 	/* Would overrun if increment makes (put==get). */
    518 	if (put_next == ms->ms_rbget) {
    519 		ms->ms_intr_flags |= INTR_RX_OVERRUN;
    520 	} else {
    521 		/* OK, really increment. */
    522 		put = put_next;
    523 	}
    524 
    525 	/* Done reading. */
    526 	ms->ms_rbput = put;
    527 
    528 	/* Ask for softint() call. */
    529 	cs->cs_softreq = 1;
    530 }
    531 
    532 
    533 static void
    534 ms_txint(cs)
    535 	register struct zs_chanstate *cs;
    536 {
    537 	register struct ms_softc *ms;
    538 
    539 	ms = cs->cs_private;
    540 	zs_write_csr(cs, ZSWR0_RESET_TXINT);
    541 	ms->ms_intr_flags |= INTR_TX_EMPTY;
    542 	/* Ask for softint() call. */
    543 	cs->cs_softreq = 1;
    544 }
    545 
    546 
    547 static void
    548 ms_stint(cs, force)
    549 	register struct zs_chanstate *cs;
    550 	int force;
    551 {
    552 	register struct ms_softc *ms;
    553 	register int rr0;
    554 
    555 	ms = cs->cs_private;
    556 
    557 	rr0 = zs_read_csr(cs);
    558 	zs_write_csr(cs, ZSWR0_RESET_STATUS);
    559 
    560 	/*
    561 	 * We have to accumulate status line changes here.
    562 	 * Otherwise, if we get multiple status interrupts
    563 	 * before the softint runs, we could fail to notice
    564 	 * some status line changes in the softint routine.
    565 	 * Fix from Bill Studenmund, October 1996.
    566 	 */
    567 	cs->cs_rr0_delta |= (cs->cs_rr0 ^ rr0);
    568 	cs->cs_rr0 = rr0;
    569 	ms->ms_intr_flags |= INTR_ST_CHECK;
    570 
    571 	/* Ask for softint() call. */
    572 	cs->cs_softreq = 1;
    573 }
    574 
    575 
    576 static void
    577 ms_softint(cs)
    578 	struct zs_chanstate *cs;
    579 {
    580 	register struct ms_softc *ms;
    581 	register int get, c, s;
    582 	int intr_flags;
    583 	register u_short ring_data;
    584 
    585 	ms = cs->cs_private;
    586 
    587 	/* Atomically get and clear flags. */
    588 	s = splzs();
    589 	intr_flags = ms->ms_intr_flags;
    590 	ms->ms_intr_flags = 0;
    591 
    592 	/* Now lower to spltty for the rest. */
    593 	(void) spltty();
    594 
    595 	/*
    596 	 * Copy data from the receive ring to the event layer.
    597 	 */
    598 	get = ms->ms_rbget;
    599 	while (get != ms->ms_rbput) {
    600 		ring_data = ms->ms_rbuf[get];
    601 		get = (get + 1) & MS_RX_RING_MASK;
    602 
    603 		/* low byte of ring_data is rr1 */
    604 		c = (ring_data >> 8) & 0xff;
    605 
    606 		if (ring_data & ZSRR1_DO)
    607 			intr_flags |= INTR_RX_OVERRUN;
    608 		if (ring_data & (ZSRR1_FE | ZSRR1_PE)) {
    609 			log(LOG_ERR, "%s: input error (0x%x)\n",
    610 				ms->ms_dev.dv_xname, ring_data);
    611 			c = -1;	/* signal input error */
    612 		}
    613 
    614 		/* Pass this up to the "middle" layer. */
    615 		ms_input(ms, c);
    616 	}
    617 	if (intr_flags & INTR_RX_OVERRUN) {
    618 		log(LOG_ERR, "%s: input overrun\n",
    619 		    ms->ms_dev.dv_xname);
    620 	}
    621 	ms->ms_rbget = get;
    622 
    623 	if (intr_flags & INTR_TX_EMPTY) {
    624 		/*
    625 		 * Transmit done.  (Not expected.)
    626 		 */
    627 		log(LOG_ERR, "%s: transmit interrupt?\n",
    628 		    ms->ms_dev.dv_xname);
    629 	}
    630 
    631 	if (intr_flags & INTR_ST_CHECK) {
    632 		/*
    633 		 * Status line change.  (Not expected.)
    634 		 */
    635 		log(LOG_ERR, "%s: status interrupt?\n",
    636 		    ms->ms_dev.dv_xname);
    637 		cs->cs_rr0_delta = 0;
    638 	}
    639 
    640 	splx(s);
    641 }
    642 
    643 struct zsops zsops_ms = {
    644 	ms_rxint,	/* receive char available */
    645 	ms_stint,	/* external/status */
    646 	ms_txint,	/* xmit buffer empty */
    647 	ms_softint,	/* process software interrupt */
    648 };
    649 
    650 
    651 static void
    652 ms_trigger (cs, onoff)
    653 	struct zs_chanstate *cs;
    654 	int onoff;
    655 {
    656 	/* for front connected one */
    657 	if (onoff)
    658 		cs->cs_preg[5] |= ZSWR5_RTS;
    659 	else
    660 		cs->cs_preg[5] &= ~ZSWR5_RTS;
    661 	cs->cs_creg[5] = cs->cs_preg[5];
    662 	zs_write_reg(cs, 5, cs->cs_preg[5]);
    663 
    664 	/* for keyborad connected one */
    665 	mfp_send_usart (onoff | 0x40);
    666 }
    667 
    668 /*
    669  * mouse timer interrupt.
    670  * called after system tick interrupt is done.
    671  */
    672 void
    673 ms_modem(arg)
    674 	void *arg;
    675 {
    676 	struct ms_softc *ms = arg;
    677 	int s;
    678 
    679 	if (!ms->ms_ready)
    680 		return;
    681 
    682 	s = splzs();
    683 
    684 	if (ms->ms_nodata++ > 250) { /* XXX */
    685 		log(LOG_ERR, "%s: no data for 5 secs. resetting.\n",
    686 		    ms->ms_dev.dv_xname);
    687 		ms->ms_byteno = -1;
    688 		ms->ms_nodata = 0;
    689 		ms->ms_rts = 0;
    690 	}
    691 
    692 	if (ms->ms_rts) {
    693 		if (ms->ms_byteno == -1) {
    694 			/* start next sequence */
    695 			ms->ms_rts = 0;
    696 			ms_trigger(ms->ms_cs, ms->ms_rts);
    697 			ms->ms_byteno = 0;
    698 		}
    699 	} else {
    700 		ms->ms_rts = 1;
    701 		ms_trigger(ms->ms_cs, ms->ms_rts);
    702 	}
    703 
    704 	(void) splx(s);
    705 	callout_reset(&ms->ms_modem_ch, 2, ms_modem, ms);
    706 }
    707