Home | History | Annotate | Line # | Download | only in dev
ms.c revision 1.36
      1 /*	$NetBSD: ms.c,v 1.36 2021/04/24 16:24:14 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  * 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 1.36 2021/04/24 16:24:14 tsutsui 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 #include <sys/mutex.h>
     61 
     62 #include <dev/ic/z8530reg.h>
     63 #include <machine/z8530var.h>
     64 
     65 #include <arch/x68k/dev/event_var.h>
     66 #include <machine/vuid_event.h>
     67 #include <arch/x68k/dev/mfp.h>
     68 
     69 #include "ioconf.h"
     70 #include "locators.h"
     71 
     72 /*
     73  * How many input characters we can buffer.
     74  * The port-specific var.h may override this.
     75  * Note: must be a power of two!
     76  */
     77 #define	MS_RX_RING_SIZE	256
     78 #define MS_RX_RING_MASK (MS_RX_RING_SIZE-1)
     79 /*
     80  * Output buffer.  Only need a few chars.
     81  */
     82 #define	MS_TX_RING_SIZE	16
     83 #define MS_TX_RING_MASK (MS_TX_RING_SIZE-1)
     84 /*
     85  * Mouse serial line is fixed at 4800 bps.
     86  */
     87 #define MS_BPS 4800
     88 
     89 /*
     90  * Send mouse commands per MS_TICK.
     91  */
     92 #ifndef HZ
     93 #define HZ		100
     94 #endif
     95 #define MS_TICK		2
     96 #define MS_TIMEOUT_SEC	5
     97 #define MS_TIMEOUT	((MS_TIMEOUT_SEC * HZ) / MS_TICK)
     98 
     99 /*
    100  * Mouse state.  A SHARP X1/X680x0 mouse is a fairly simple device,
    101  * producing three-byte blobs of the form:
    102  *
    103  *	b dx dy
    104  *
    105  * where b is the button state, encoded as 0x80|(buttons)---there are
    106  * two buttons (2=left, 1=right)---and dx,dy are X and Y delta values.
    107  *
    108  * It needs a trigger for the transmission.  When zs RTS negated, the
    109  * mouse begins the sequence.  RTS assertion has no effect.
    110  */
    111 struct ms_softc {
    112 	device_t ms_dev;		/* required first: base device */
    113 	struct	zs_chanstate *ms_cs;
    114 
    115 	struct callout ms_modem_ch;
    116 
    117 	/* Flags to communicate with ms_softintr() */
    118 	volatile int ms_intr_flags;
    119 #define	INTR_RX_OVERRUN 1
    120 #define INTR_TX_EMPTY   2
    121 #define INTR_ST_CHECK   4
    122 
    123 	/*
    124 	 * The receive ring buffer.
    125 	 */
    126 	u_int	ms_rbget;	/* ring buffer `get' index */
    127 	volatile u_int	ms_rbput;	/* ring buffer `put' index */
    128 	u_short	ms_rbuf[MS_RX_RING_SIZE]; /* rr1, data pairs */
    129 
    130 	/*
    131 	 * State of input translator
    132 	 */
    133 	short	ms_byteno;		/* input byte number, for decode */
    134 	char	ms_mb;			/* mouse button state */
    135 	char	ms_ub;			/* user button state */
    136 	int	ms_dx;			/* delta-x */
    137 	int	ms_dy;			/* delta-y */
    138 	int	ms_rts;			/* MSCTRL */
    139 	int	ms_nodata;
    140 
    141 	/*
    142 	 * State of upper interface.
    143 	 */
    144 	volatile int ms_ready;		/* event queue is ready */
    145 	struct	evvar ms_events;	/* event queue state */
    146 	kmutex_t ms_lock;
    147 } ms_softc;
    148 
    149 static int ms_match(device_t, cfdata_t, void *);
    150 static void ms_attach(device_t, device_t, void *);
    151 static void ms_trigger(struct zs_chanstate *, int);
    152 void ms_modem(void *);
    153 
    154 CFATTACH_DECL_NEW(ms, sizeof(struct ms_softc),
    155     ms_match, ms_attach, NULL, NULL);
    156 
    157 static void ms_rxint(struct zs_chanstate *);
    158 static void ms_stint(struct zs_chanstate *, int);
    159 static void ms_txint(struct zs_chanstate *);
    160 static void ms_softint(struct zs_chanstate *);
    161 static void ms_input(struct ms_softc *, int);
    162 
    163 struct zsops zsops_ms = {
    164 	ms_rxint,	/* receive char available */
    165 	ms_stint,	/* external/status */
    166 	ms_txint,	/* xmit buffer empty */
    167 	ms_softint,	/* process software interrupt */
    168 };
    169 
    170 dev_type_open(msopen);
    171 dev_type_close(msclose);
    172 dev_type_read(msread);
    173 dev_type_ioctl(msioctl);
    174 dev_type_poll(mspoll);
    175 dev_type_kqfilter(mskqfilter);
    176 
    177 const struct cdevsw ms_cdevsw ={
    178 	.d_open = msopen,
    179 	.d_close = msclose,
    180 	.d_read = msread,
    181 	.d_write = nowrite,
    182 	.d_ioctl = msioctl,
    183 	.d_stop = nostop,
    184 	.d_tty = notty,
    185 	.d_poll = mspoll,
    186 	.d_mmap = nommap,
    187 	.d_kqfilter = mskqfilter,
    188 	.d_discard = nodiscard,
    189 	.d_flag = 0
    190 };
    191 
    192 /*
    193  * ms_match: how is this zs channel configured?
    194  */
    195 int
    196 ms_match(device_t parent, cfdata_t cf, void *aux)
    197 {
    198 	struct zsc_attach_args *args = aux;
    199 	struct zsc_softc *zsc = device_private(parent);
    200 
    201 	/* Exact match required for the mouse. */
    202 	if (cf->cf_loc[ZSCCF_CHANNEL] != args->channel)
    203 		return 0;
    204 	if (args->channel != 1)
    205 		return 0;
    206 	if (&zsc->zsc_addr->zs_chan_b != (struct zschan *)ZSMS_PHYSADDR)
    207 		return 0;
    208 
    209 	return 2;
    210 }
    211 
    212 void
    213 ms_attach(device_t parent, device_t self, void *aux)
    214 {
    215 	struct ms_softc *ms = device_private(self);
    216 	struct zsc_softc *zsc = device_private(parent);
    217 	struct zs_chanstate *cs;
    218 	int reset;
    219 
    220 	ms->ms_dev = self;
    221 	callout_init(&ms->ms_modem_ch, 0);
    222 	mutex_init(&ms->ms_lock, MUTEX_DEFAULT, IPL_SERIAL);
    223 
    224 	cs = zsc->zsc_cs[1];
    225 	cs->cs_private = ms;
    226 	cs->cs_ops = &zsops_ms;
    227 	ms->ms_cs = cs;
    228 
    229 	/* Initialize the speed, etc. */
    230 	/* May need reset... */
    231 	reset = ZSWR9_B_RESET;
    232 	zs_write_reg(cs, 9, reset);
    233 	/* We don't care about status or tx interrupts. */
    234 	cs->cs_preg[1] = ZSWR1_RIE;
    235 	cs->cs_preg[4] = ZSWR4_CLK_X16 | ZSWR4_TWOSB;
    236 	(void)zs_set_speed(cs, MS_BPS);
    237 	zs_loadchannelregs(cs);
    238 
    239 	/* Initialize translator. */
    240 	ms->ms_ready = 0;
    241 
    242 	aprint_normal("\n");
    243 }
    244 
    245 /****************************************************************
    246  *  Entry points for /dev/mouse
    247  *  (open,close,read,write,...)
    248  ****************************************************************/
    249 
    250 int
    251 msopen(dev_t dev, int flags, int mode, struct lwp *l)
    252 {
    253 	struct ms_softc *ms;
    254 
    255 	ms = device_lookup_private(&ms_cd, minor(dev));
    256 	if (ms == NULL)
    257 		return ENXIO;
    258 
    259 	/* This is an exclusive open device. */
    260 	if (ms->ms_events.ev_io)
    261 		return EBUSY;
    262 	ms->ms_events.ev_io = l->l_proc;
    263 	ev_init(&ms->ms_events, device_xname(ms->ms_dev), &ms->ms_lock);
    264 
    265 	ms->ms_ready = 1;		/* start accepting events */
    266 	ms->ms_rts = 1;
    267 	ms->ms_byteno = -1;
    268 	ms->ms_nodata = 0;
    269 
    270 	/* start sequencer */
    271 	callout_reset(&ms->ms_modem_ch, MS_TICK, ms_modem, ms);
    272 
    273 	return 0;
    274 }
    275 
    276 int
    277 msclose(dev_t dev, int flags, int mode, struct lwp *l)
    278 {
    279 	struct ms_softc *ms;
    280 
    281 	ms = device_lookup_private(&ms_cd, minor(dev));
    282 	ms->ms_ready = 0;		/* stop accepting events */
    283 	callout_stop(&ms->ms_modem_ch);
    284 	ev_fini(&ms->ms_events);
    285 
    286 	ms->ms_events.ev_io = NULL;
    287 	return 0;
    288 }
    289 
    290 int
    291 msread(dev_t dev, struct uio *uio, int flags)
    292 {
    293 	struct ms_softc *ms;
    294 
    295 	ms = device_lookup_private(&ms_cd, minor(dev));
    296 	return ev_read(&ms->ms_events, uio, flags);
    297 }
    298 
    299 int
    300 msioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
    301 {
    302 	struct ms_softc *ms;
    303 
    304 	ms = device_lookup_private(&ms_cd, minor(dev));
    305 
    306 	switch (cmd) {
    307 
    308 	case FIONBIO:		/* we will remove this someday (soon???) */
    309 		return 0;
    310 
    311 	case FIOASYNC:
    312 		ms->ms_events.ev_async = *(int *)data != 0;
    313 		return 0;
    314 
    315 	case FIOSETOWN:
    316 		if (-*(int *)data != ms->ms_events.ev_io->p_pgid
    317 		    && *(int *)data != ms->ms_events.ev_io->p_pid)
    318 			return EPERM;
    319 		return 0;
    320 
    321 	case TIOCSPGRP:
    322 		if (*(int *)data != ms->ms_events.ev_io->p_pgid)
    323 			return EPERM;
    324 		return 0;
    325 
    326 	case VUIDGFORMAT:
    327 		/* we only do firm_events */
    328 		*(int *)data = VUID_FIRM_EVENT;
    329 		return 0;
    330 
    331 	case VUIDSFORMAT:
    332 		if (*(int *)data != VUID_FIRM_EVENT)
    333 			return EINVAL;
    334 		return 0;
    335 	}
    336 	return ENOTTY;
    337 }
    338 
    339 int
    340 mspoll(dev_t dev, int events, struct lwp *l)
    341 {
    342 	struct ms_softc *ms;
    343 
    344 	ms = device_lookup_private(&ms_cd, minor(dev));
    345 	return ev_poll(&ms->ms_events, events, l);
    346 }
    347 
    348 int
    349 mskqfilter(dev_t dev, struct knote *kn)
    350 {
    351 	struct ms_softc *ms;
    352 
    353 	ms = device_lookup_private(&ms_cd, minor(dev));
    354 	return ev_kqfilter(&ms->ms_events, kn);
    355 }
    356 
    357 /****************************************************************
    358  * Middle layer (translator)
    359  ****************************************************************/
    360 
    361 /*
    362  * Called by our ms_softint() routine on input.
    363  */
    364 static void
    365 ms_input(struct ms_softc *ms, int c)
    366 {
    367 	struct firm_event *fe;
    368 	int mb, ub, d, get, put, any;
    369 	static const char to_one[] = { 1, 2, 2 };
    370 	static const int to_id[] = { MS_LEFT, MS_RIGHT };
    371 
    372 	/*
    373 	 * Discard input if not ready.  Drop sync on parity or framing
    374 	 * error; gain sync on button byte.
    375 	 */
    376 	if (ms->ms_ready == 0)
    377 		return;
    378 
    379 	ms->ms_nodata = 0;
    380 	/*
    381 	 * Run the decode loop, adding to the current information.
    382 	 * We add, rather than replace, deltas, so that if the event queue
    383 	 * fills, we accumulate data for when it opens up again.
    384 	 */
    385 	switch (ms->ms_byteno) {
    386 
    387 	case -1:
    388 		return;
    389 
    390 	case 0:
    391 		/* buttons */
    392 		ms->ms_byteno = 1;
    393 		ms->ms_mb = c & 0x3;
    394 		return;
    395 
    396 	case 1:
    397 		/* delta-x */
    398 		ms->ms_byteno = 2;
    399 		ms->ms_dx += (char)c;
    400 		return;
    401 
    402 	case 2:
    403 		/* delta-y */
    404 		ms->ms_byteno = -1;
    405 		ms->ms_dy += (char)c;
    406 		break;
    407 
    408 	default:
    409 		panic("ms_input");
    410 		/* NOTREACHED */
    411 	}
    412 
    413 	/*
    414 	 * We have at least one event (mouse button, delta-X, or
    415 	 * delta-Y; possibly all three, and possibly two separate
    416 	 * button events).  Deliver these events until we are out
    417 	 * of changes or out of room.  As events get delivered,
    418 	 * mark them `unchanged'.
    419 	 */
    420 	any = 0;
    421 	get = ms->ms_events.ev_get;
    422 	put = ms->ms_events.ev_put;
    423 	fe = &ms->ms_events.ev_q[put];
    424 
    425 	/* NEXT prepares to put the next event, backing off if necessary */
    426 #define	NEXT \
    427 	if ((++put) % EV_QSIZE == get) { \
    428 		put--; \
    429 		goto out; \
    430 	}
    431 	/* ADVANCE completes the `put' of the event */
    432 #define	ADVANCE \
    433 	fe++; \
    434 	if (put >= EV_QSIZE) { \
    435 		put = 0; \
    436 		fe = &ms->ms_events.ev_q[0]; \
    437 	} \
    438 
    439 	mb = ms->ms_mb;
    440 	ub = ms->ms_ub;
    441 	while ((d = mb ^ ub) != 0) {
    442 		/*
    443 		 * Mouse button change.  Convert up to two changes
    444 		 * to the `first' change, and drop it into the event queue.
    445 		 */
    446 		NEXT;
    447 		d = to_one[d - 1];		/* from 1..3 to {1,2} */
    448 		fe->id = to_id[d - 1];		/* from {1,2} to ID */
    449 		fe->value = mb & d ? VKEY_DOWN : VKEY_UP;
    450 		firm_gettime(fe);
    451 		ADVANCE;
    452 		ub ^= d;
    453 		any++;
    454 	}
    455 	if (ms->ms_dx) {
    456 		NEXT;
    457 		fe->id = LOC_X_DELTA;
    458 		fe->value = ms->ms_dx;
    459 		firm_gettime(fe);
    460 		ADVANCE;
    461 		ms->ms_dx = 0;
    462 		any++;
    463 	}
    464 	if (ms->ms_dy) {
    465 		NEXT;
    466 		fe->id = LOC_Y_DELTA;
    467 		fe->value = -ms->ms_dy;	/* XXX? */
    468 		firm_gettime(fe);
    469 		ADVANCE;
    470 		ms->ms_dy = 0;
    471 		any++;
    472 	}
    473 out:
    474 	if (any) {
    475 		ms->ms_ub = ub;
    476 		ms->ms_events.ev_put = put;
    477 		ev_wakeup(&ms->ms_events);
    478 	}
    479 }
    480 
    481 /****************************************************************
    482  * Interface to the lower layer (zscc)
    483  ****************************************************************/
    484 
    485 static void
    486 ms_rxint(struct zs_chanstate *cs)
    487 {
    488 	struct ms_softc *ms;
    489 	int put, put_next;
    490 	u_char c, rr1;
    491 
    492 	ms = cs->cs_private;
    493 	put = ms->ms_rbput;
    494 
    495 	/*
    496 	 * First read the status, because reading the received char
    497 	 * destroys the status of this char.
    498 	 */
    499 	rr1 = zs_read_reg(cs, 1);
    500 	c = zs_read_data(cs);
    501 
    502 	if (rr1 & (ZSRR1_FE | ZSRR1_DO | ZSRR1_PE)) {
    503 		/* Clear the receive error. */
    504 		zs_write_csr(cs, ZSWR0_RESET_ERRORS);
    505 	}
    506 
    507 	ms->ms_rbuf[put] = (c << 8) | rr1;
    508 	put_next = (put + 1) & MS_RX_RING_MASK;
    509 
    510 	/* Would overrun if increment makes (put==get). */
    511 	if (put_next == ms->ms_rbget) {
    512 		ms->ms_intr_flags |= INTR_RX_OVERRUN;
    513 	} else {
    514 		/* OK, really increment. */
    515 		put = put_next;
    516 	}
    517 
    518 	/* Done reading. */
    519 	ms->ms_rbput = put;
    520 
    521 	/* Ask for softint() call. */
    522 	cs->cs_softreq = 1;
    523 }
    524 
    525 
    526 static void
    527 ms_txint(struct zs_chanstate *cs)
    528 {
    529 	struct ms_softc *ms;
    530 
    531 	ms = cs->cs_private;
    532 	zs_write_csr(cs, ZSWR0_RESET_TXINT);
    533 	ms->ms_intr_flags |= INTR_TX_EMPTY;
    534 	/* Ask for softint() call. */
    535 	cs->cs_softreq = 1;
    536 }
    537 
    538 
    539 static void
    540 ms_stint(struct zs_chanstate *cs, int force)
    541 {
    542 	struct ms_softc *ms;
    543 	int rr0;
    544 
    545 	ms = cs->cs_private;
    546 
    547 	rr0 = zs_read_csr(cs);
    548 	zs_write_csr(cs, ZSWR0_RESET_STATUS);
    549 
    550 	/*
    551 	 * We have to accumulate status line changes here.
    552 	 * Otherwise, if we get multiple status interrupts
    553 	 * before the softint runs, we could fail to notice
    554 	 * some status line changes in the softint routine.
    555 	 * Fix from Bill Studenmund, October 1996.
    556 	 */
    557 	cs->cs_rr0_delta |= (cs->cs_rr0 ^ rr0);
    558 	cs->cs_rr0 = rr0;
    559 	ms->ms_intr_flags |= INTR_ST_CHECK;
    560 
    561 	/* Ask for softint() call. */
    562 	cs->cs_softreq = 1;
    563 }
    564 
    565 
    566 static void
    567 ms_softint(struct zs_chanstate *cs)
    568 {
    569 	struct ms_softc *ms;
    570 	int get, c;
    571 	int intr_flags;
    572 	u_short ring_data;
    573 
    574 	ms = cs->cs_private;
    575 
    576 	mutex_enter(&ms->ms_lock);
    577 	intr_flags = ms->ms_intr_flags;
    578 	ms->ms_intr_flags = 0;
    579 
    580 	/*
    581 	 * Copy data from the receive ring to the event layer.
    582 	 */
    583 	get = ms->ms_rbget;
    584 	while (get != ms->ms_rbput) {
    585 		ring_data = ms->ms_rbuf[get];
    586 		mutex_exit(&ms->ms_lock);
    587 		get = (get + 1) & MS_RX_RING_MASK;
    588 
    589 		/* low byte of ring_data is rr1 */
    590 		c = (ring_data >> 8) & 0xff;
    591 
    592 		if (ring_data & ZSRR1_DO)
    593 			intr_flags |= INTR_RX_OVERRUN;
    594 		if (ring_data & (ZSRR1_FE | ZSRR1_PE)) {
    595 			log(LOG_ERR, "%s: input error (0x%x)\n",
    596 			    device_xname(ms->ms_dev), ring_data);
    597 			c = -1;	/* signal input error */
    598 		}
    599 
    600 		/* Pass this up to the "middle" layer. */
    601 		ms_input(ms, c);
    602 		mutex_enter(&ms->ms_lock);
    603 	}
    604 	mutex_exit(&ms->ms_lock);
    605 
    606 	if (intr_flags & INTR_RX_OVERRUN) {
    607 		log(LOG_ERR, "%s: input overrun\n",
    608 		    device_xname(ms->ms_dev));
    609 	}
    610 	ms->ms_rbget = get;
    611 
    612 	if (intr_flags & INTR_TX_EMPTY) {
    613 		/*
    614 		 * Transmit done.  (Not expected.)
    615 		 */
    616 		log(LOG_ERR, "%s: transmit interrupt?\n",
    617 		    device_xname(ms->ms_dev));
    618 	}
    619 
    620 	if (intr_flags & INTR_ST_CHECK) {
    621 		/*
    622 		 * Status line change.  (Not expected.)
    623 		 */
    624 		log(LOG_ERR, "%s: status interrupt?\n",
    625 		    device_xname(ms->ms_dev));
    626 		mutex_enter(&ms->ms_lock);
    627 		cs->cs_rr0_delta = 0;
    628 		mutex_exit(&ms->ms_lock);
    629 	}
    630 }
    631 
    632 
    633 static void
    634 ms_trigger(struct zs_chanstate *cs, int onoff)
    635 {
    636 	/* for front connected one */
    637 	if (onoff)
    638 		cs->cs_preg[5] |= ZSWR5_RTS;
    639 	else
    640 		cs->cs_preg[5] &= ~ZSWR5_RTS;
    641 	cs->cs_creg[5] = cs->cs_preg[5];
    642 	zs_write_reg(cs, 5, cs->cs_preg[5]);
    643 
    644 	/* for keyborad connected one */
    645 	mfp_send_usart(onoff | 0x40);
    646 }
    647 
    648 /*
    649  * mouse timer interrupt.
    650  * called after system tick interrupt is done.
    651  */
    652 void
    653 ms_modem(void *arg)
    654 {
    655 	struct ms_softc *ms = arg;
    656 
    657 	if (!ms->ms_ready)
    658 		return;
    659 
    660 	mutex_enter(&ms->ms_lock);
    661 
    662 	if (ms->ms_nodata++ > MS_TIMEOUT) {
    663 		log(LOG_ERR, "%s: no data for %d secs. resetting.\n",
    664 		    device_xname(ms->ms_dev), MS_TIMEOUT_SEC);
    665 		ms->ms_byteno = -1;
    666 		ms->ms_nodata = 0;
    667 		ms->ms_rts = 0;
    668 	}
    669 
    670 	if (ms->ms_rts) {
    671 		if (ms->ms_byteno == -1) {
    672 			/* start next sequence */
    673 			ms->ms_rts = 0;
    674 			ms_trigger(ms->ms_cs, ms->ms_rts);
    675 			ms->ms_byteno = 0;
    676 		}
    677 	} else {
    678 		ms->ms_rts = 1;
    679 		ms_trigger(ms->ms_cs, ms->ms_rts);
    680 	}
    681 
    682 	mutex_exit(&ms->ms_lock);
    683 	callout_schedule(&ms->ms_modem_ch, MS_TICK);
    684 }
    685