xref: /freebsd/sys/dev/dcons/dcons_os.c (revision d056fa046c6a91b90cd98165face0e42a33a5173)
1 /*-
2  * Copyright (C) 2003,2004
3  * 	Hidetoshi Shimokawa. All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. All advertising materials mentioning features or use of this software
14  *    must display the following acknowledgement:
15  *
16  *	This product includes software developed by Hidetoshi Shimokawa.
17  *
18  * 4. Neither the name of the author nor the names of its contributors
19  *    may be used to endorse or promote products derived from this software
20  *    without specific prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  *
34  * $FreeBSD$
35  */
36 
37 #include <sys/param.h>
38 #if __FreeBSD_version >= 502122
39 #include <sys/kdb.h>
40 #include <gdb/gdb.h>
41 #endif
42 #include <sys/kernel.h>
43 #include <sys/module.h>
44 #include <sys/systm.h>
45 #include <sys/types.h>
46 #include <sys/conf.h>
47 #include <sys/cons.h>
48 #include <sys/consio.h>
49 #include <sys/tty.h>
50 #include <sys/malloc.h>
51 #include <sys/proc.h>
52 #include <sys/ucred.h>
53 
54 #include <machine/bus.h>
55 
56 #ifdef __DragonFly__
57 #include "dcons.h"
58 #include "dcons_os.h"
59 #else
60 #include <dev/dcons/dcons.h>
61 #include <dev/dcons/dcons_os.h>
62 #endif
63 
64 #include <ddb/ddb.h>
65 #include <sys/reboot.h>
66 
67 #include <sys/sysctl.h>
68 
69 #include <vm/vm.h>
70 #include <vm/vm_param.h>
71 #include <vm/pmap.h>
72 
73 #include "opt_ddb.h"
74 #include "opt_comconsole.h"
75 #include "opt_dcons.h"
76 
77 #ifndef DCONS_POLL_HZ
78 #define DCONS_POLL_HZ	100
79 #endif
80 
81 #ifndef DCONS_BUF_SIZE
82 #define DCONS_BUF_SIZE (16*1024)
83 #endif
84 
85 #ifndef DCONS_FORCE_CONSOLE
86 #define DCONS_FORCE_CONSOLE	0	/* Mostly for FreeBSD-4/DragonFly */
87 #endif
88 
89 #ifndef DCONS_FORCE_GDB
90 #define DCONS_FORCE_GDB	1
91 #endif
92 
93 #if __FreeBSD_version >= 500101
94 #define CONS_NODEV	1
95 #if __FreeBSD_version < 502122
96 static struct consdev gdbconsdev;
97 #endif
98 #endif
99 
100 static d_open_t		dcons_open;
101 static d_close_t	dcons_close;
102 #if defined(__DragonFly__) || __FreeBSD_version < 500104
103 static d_ioctl_t	dcons_ioctl;
104 #endif
105 
106 static struct cdevsw dcons_cdevsw = {
107 #ifdef __DragonFly__
108 #define CDEV_MAJOR      184
109 	"dcons", CDEV_MAJOR, D_TTY, NULL, 0,
110 	dcons_open, dcons_close, ttyread, ttywrite, dcons_ioctl,
111 	ttypoll, nommap, nostrategy, nodump, nopsize,
112 #elif __FreeBSD_version >= 500104
113 	.d_version =	D_VERSION,
114 	.d_open =	dcons_open,
115 	.d_close =	dcons_close,
116 	.d_name =	"dcons",
117 	.d_flags =	D_TTY | D_NEEDGIANT,
118 #else
119 #define CDEV_MAJOR      184
120 	/* open */	dcons_open,
121 	/* close */	dcons_close,
122 	/* read */	ttyread,
123 	/* write */	ttywrite,
124 	/* ioctl */	dcons_ioctl,
125 	/* poll */	ttypoll,
126 	/* mmap */	nommap,
127 	/* strategy */	nostrategy,
128 	/* name */	"dcons",
129 	/* major */	CDEV_MAJOR,
130 	/* dump */	nodump,
131 	/* psize */	nopsize,
132 	/* flags */	D_TTY,
133 #endif
134 };
135 
136 #ifndef KLD_MODULE
137 static char bssbuf[DCONS_BUF_SIZE];	/* buf in bss */
138 #endif
139 
140 /* global data */
141 static struct dcons_global dg;
142 struct dcons_global *dcons_conf;
143 static int poll_hz = DCONS_POLL_HZ;
144 
145 static struct dcons_softc sc[DCONS_NPORT];
146 
147 SYSCTL_NODE(_kern, OID_AUTO, dcons, CTLFLAG_RD, 0, "Dumb Console");
148 SYSCTL_INT(_kern_dcons, OID_AUTO, poll_hz, CTLFLAG_RW, &poll_hz, 0,
149 				"dcons polling rate");
150 
151 static int drv_init = 0;
152 static struct callout dcons_callout;
153 struct dcons_buf *dcons_buf;		/* for local dconschat */
154 
155 #ifdef __DragonFly__
156 #define DEV	dev_t
157 #define THREAD	d_thread_t
158 #elif __FreeBSD_version < 500000
159 #define DEV	dev_t
160 #define THREAD	struct proc
161 #else
162 #define DEV	struct cdev *
163 #define THREAD	struct thread
164 #endif
165 
166 
167 static void	dcons_tty_start(struct tty *);
168 static int	dcons_tty_param(struct tty *, struct termios *);
169 static void	dcons_timeout(void *);
170 static int	dcons_drv_init(int);
171 
172 static cn_probe_t	dcons_cnprobe;
173 static cn_init_t	dcons_cninit;
174 static cn_term_t	dcons_cnterm;
175 static cn_getc_t	dcons_cngetc;
176 static cn_putc_t	dcons_cnputc;
177 
178 CONSOLE_DRIVER(dcons);
179 
180 #if __FreeBSD_version >= 502122
181 static gdb_probe_f dcons_dbg_probe;
182 static gdb_init_f dcons_dbg_init;
183 static gdb_term_f dcons_dbg_term;
184 static gdb_getc_f dcons_dbg_getc;
185 static gdb_putc_f dcons_dbg_putc;
186 
187 GDB_DBGPORT(dcons, dcons_dbg_probe, dcons_dbg_init, dcons_dbg_term,
188     dcons_dbg_getc, dcons_dbg_putc);
189 
190 extern struct gdb_dbgport *gdb_cur;
191 #endif
192 
193 #if (defined(KDB) || defined(DDB)) && defined(ALT_BREAK_TO_DEBUGGER)
194 static int
195 dcons_check_break(struct dcons_softc *dc, int c)
196 {
197 	if (c < 0)
198 		return (c);
199 
200 #if __FreeBSD_version >= 502122
201 	if (kdb_alt_break(c, &dc->brk_state)) {
202 		if ((dc->flags & DC_GDB) != 0) {
203 			if (gdb_cur == &dcons_gdb_dbgport) {
204 				kdb_dbbe_select("gdb");
205 				breakpoint();
206 			}
207 		} else
208 			breakpoint();
209 	}
210 #else
211 	switch (dc->brk_state) {
212 	case STATE1:
213 		if (c == KEY_TILDE)
214 			dc->brk_state = STATE2;
215 		else
216 			dc->brk_state = STATE0;
217 		break;
218 	case STATE2:
219 		dc->brk_state = STATE0;
220 		if (c == KEY_CTRLB) {
221 #if DCONS_FORCE_GDB
222 			if (dc->flags & DC_GDB)
223 				boothowto |= RB_GDB;
224 #endif
225 			breakpoint();
226 		}
227 	}
228 	if (c == KEY_CR)
229 		dc->brk_state = STATE1;
230 #endif
231 	return (c);
232 }
233 #else
234 #define	dcons_check_break(dc, c)	(c)
235 #endif
236 
237 static int
238 dcons_os_checkc(struct dcons_softc *dc)
239 {
240 	int c;
241 
242 	if (dg.dma_tag != NULL)
243 		bus_dmamap_sync(dg.dma_tag, dg.dma_map, BUS_DMASYNC_POSTREAD);
244 
245 	c = dcons_check_break(dc, dcons_checkc(dc));
246 
247 	if (dg.dma_tag != NULL)
248 		bus_dmamap_sync(dg.dma_tag, dg.dma_map, BUS_DMASYNC_PREREAD);
249 
250 	return (c);
251 }
252 
253 static int
254 dcons_os_getc(struct dcons_softc *dc)
255 {
256 	int c;
257 
258 	while ((c = dcons_os_checkc(dc)) == -1);
259 
260 	return (c & 0xff);
261 }
262 
263 static void
264 dcons_os_putc(struct dcons_softc *dc, int c)
265 {
266 	if (dg.dma_tag != NULL)
267 		bus_dmamap_sync(dg.dma_tag, dg.dma_map, BUS_DMASYNC_POSTWRITE);
268 
269 	dcons_putc(dc, c);
270 
271 	if (dg.dma_tag != NULL)
272 		bus_dmamap_sync(dg.dma_tag, dg.dma_map, BUS_DMASYNC_PREWRITE);
273 }
274 static int
275 dcons_open(DEV dev, int flag, int mode, THREAD *td)
276 {
277 	struct tty *tp;
278 	int unit, error, s;
279 
280 	unit = minor(dev);
281 	if (unit != 0)
282 		return (ENXIO);
283 
284 	tp = dev->si_tty;
285 	tp->t_oproc = dcons_tty_start;
286 	tp->t_param = dcons_tty_param;
287 	tp->t_stop = nottystop;
288 	tp->t_dev = dev;
289 
290 	error = 0;
291 
292 	s = spltty();
293 	if ((tp->t_state & TS_ISOPEN) == 0) {
294 		tp->t_state |= TS_CARR_ON;
295 		ttyconsolemode(tp, 0);
296 	} else if ((tp->t_state & TS_XCLUDE) && suser(td)) {
297 		splx(s);
298 		return (EBUSY);
299 	}
300 	splx(s);
301 
302 #if __FreeBSD_version < 502113
303 	error = (*linesw[tp->t_line].l_open)(dev, tp);
304 #else
305 	error = ttyld_open(tp, dev);
306 #endif
307 
308 	return (error);
309 }
310 
311 static int
312 dcons_close(DEV dev, int flag, int mode, THREAD *td)
313 {
314 	int	unit;
315 	struct	tty *tp;
316 
317 	unit = minor(dev);
318 	if (unit != 0)
319 		return (ENXIO);
320 
321 	tp = dev->si_tty;
322 	if (tp->t_state & TS_ISOPEN) {
323 #if __FreeBSD_version < 502113
324 		(*linesw[tp->t_line].l_close)(tp, flag);
325 		ttyclose(tp);
326 #else
327 		ttyld_close(tp, flag);
328 		tty_close(tp);
329 #endif
330 	}
331 
332 	return (0);
333 }
334 
335 #if defined(__DragonFly__) || __FreeBSD_version < 500104
336 static int
337 dcons_ioctl(DEV dev, u_long cmd, caddr_t data, int flag, THREAD *td)
338 {
339 	int	unit;
340 	struct	tty *tp;
341 	int	error;
342 
343 	unit = minor(dev);
344 	if (unit != 0)
345 		return (ENXIO);
346 
347 	tp = dev->si_tty;
348 	error = (*linesw[tp->t_line].l_ioctl)(tp, cmd, data, flag, td);
349 	if (error != ENOIOCTL)
350 		return (error);
351 
352 	error = ttioctl(tp, cmd, data, flag);
353 	if (error != ENOIOCTL)
354 		return (error);
355 
356 	return (ENOTTY);
357 }
358 #endif
359 
360 static int
361 dcons_tty_param(struct tty *tp, struct termios *t)
362 {
363 	tp->t_ispeed = t->c_ispeed;
364 	tp->t_ospeed = t->c_ospeed;
365 	tp->t_cflag = t->c_cflag;
366 	return 0;
367 }
368 
369 static void
370 dcons_tty_start(struct tty *tp)
371 {
372 	struct dcons_softc *dc;
373 	int s;
374 
375 	dc = (struct dcons_softc *)tp->t_dev->si_drv1;
376 	s = spltty();
377 	if (tp->t_state & (TS_TIMEOUT | TS_TTSTOP)) {
378 		ttwwakeup(tp);
379 		return;
380 	}
381 
382 	tp->t_state |= TS_BUSY;
383 	while (tp->t_outq.c_cc != 0)
384 		dcons_os_putc(dc, getc(&tp->t_outq));
385 	tp->t_state &= ~TS_BUSY;
386 
387 	ttwwakeup(tp);
388 	splx(s);
389 }
390 
391 static void
392 dcons_timeout(void *v)
393 {
394 	struct	tty *tp;
395 	struct dcons_softc *dc;
396 	int i, c, polltime;
397 
398 	for (i = 0; i < DCONS_NPORT; i ++) {
399 		dc = &sc[i];
400 		tp = ((DEV)dc->dev)->si_tty;
401 		while ((c = dcons_os_checkc(dc)) != -1)
402 			if (tp->t_state & TS_ISOPEN)
403 #if __FreeBSD_version < 502113
404 				(*linesw[tp->t_line].l_rint)(c, tp);
405 #else
406 				ttyld_rint(tp, c);
407 #endif
408 	}
409 	polltime = hz / poll_hz;
410 	if (polltime < 1)
411 		polltime = 1;
412 	callout_reset(&dcons_callout, polltime, dcons_timeout, tp);
413 }
414 
415 static void
416 dcons_cnprobe(struct consdev *cp)
417 {
418 #ifdef __DragonFly__
419 	cp->cn_dev = make_dev(&dcons_cdevsw, DCONS_CON,
420 	    UID_ROOT, GID_WHEEL, 0600, "dcons");
421 #elif __FreeBSD_version >= 501109
422 	sprintf(cp->cn_name, "dcons");
423 #else
424 	cp->cn_dev = makedev(CDEV_MAJOR, DCONS_CON);
425 #endif
426 #if DCONS_FORCE_CONSOLE
427 	cp->cn_pri = CN_REMOTE;
428 #else
429 	cp->cn_pri = CN_NORMAL;
430 #endif
431 }
432 
433 static void
434 dcons_cninit(struct consdev *cp)
435 {
436 	dcons_drv_init(0);
437 #if CONS_NODEV
438 	cp->cn_arg
439 #else
440 	cp->cn_dev->si_drv1
441 #endif
442 		= (void *)&sc[DCONS_CON]; /* share port0 with unit0 */
443 }
444 
445 static void
446 dcons_cnterm(struct consdev *cp)
447 {
448 }
449 
450 #if CONS_NODEV
451 static int
452 dcons_cngetc(struct consdev *cp)
453 {
454 	struct dcons_softc *dc = (struct dcons_softc *)cp->cn_arg;
455 	return (dcons_os_checkc(dc));
456 }
457 static void
458 dcons_cnputc(struct consdev *cp, int c)
459 {
460 	struct dcons_softc *dc = (struct dcons_softc *)cp->cn_arg;
461 	dcons_os_putc(dc, c);
462 }
463 #else
464 static int
465 dcons_cngetc(DEV dev)
466 {
467 	struct dcons_softc *dc = (struct dcons_softc *)dev->si_drv1;
468 	return (dcons_os_getc(dc));
469 }
470 static int
471 dcons_cncheckc(DEV dev)
472 {
473 	struct dcons_softc *dc = (struct dcons_softc *)dev->si_drv1;
474 	return (dcons_os_checkc(dc));
475 }
476 static void
477 dcons_cnputc(DEV dev, int c)
478 {
479 	struct dcons_softc *dc = (struct dcons_softc *)dev->si_drv1;
480 	dcons_os_putc(dc, c);
481 }
482 #endif
483 
484 static int
485 dcons_drv_init(int stage)
486 {
487 #if defined(__i386__) || defined(__amd64__)
488 	quad_t addr, size;
489 #endif
490 
491 	if (drv_init)
492 		return(drv_init);
493 
494 	drv_init = -1;
495 
496 	bzero(&dg, sizeof(dg));
497 	dcons_conf = &dg;
498 	dg.cdev = &dcons_consdev;
499 	dg.buf = NULL;
500 	dg.size = DCONS_BUF_SIZE;
501 
502 #if defined(__i386__) || defined(__amd64__)
503 	if (getenv_quad("dcons.addr", &addr) > 0 &&
504 	    getenv_quad("dcons.size", &size) > 0) {
505 #ifdef __i386__
506 		vm_paddr_t pa;
507 		/*
508 		 * Allow read/write access to dcons buffer.
509 		 */
510 		for (pa = trunc_page(addr); pa < addr + size; pa += PAGE_SIZE)
511 			*vtopte(KERNBASE + pa) |= PG_RW;
512 		invltlb();
513 #endif
514 		/* XXX P to V */
515 		dg.buf = (struct dcons_buf *)(vm_offset_t)(KERNBASE + addr);
516 		dg.size = size;
517 		if (dcons_load_buffer(dg.buf, dg.size, sc) < 0)
518 			dg.buf = NULL;
519 	}
520 #endif
521 	if (dg.buf != NULL)
522 		goto ok;
523 
524 #ifndef KLD_MODULE
525 	if (stage == 0) { /* XXX or cold */
526 		/*
527 		 * DCONS_FORCE_CONSOLE == 1 and statically linked.
528 		 * called from cninit(). can't use contigmalloc yet .
529 		 */
530 		dg.buf = (struct dcons_buf *) bssbuf;
531 		dcons_init(dg.buf, dg.size, sc);
532 	} else
533 #endif
534 	{
535 		/*
536 		 * DCONS_FORCE_CONSOLE == 0 or kernel module case.
537 		 * if the module is loaded after boot,
538 		 * bssbuf could be non-continuous.
539 		 */
540 		dg.buf = (struct dcons_buf *) contigmalloc(dg.size,
541 			M_DEVBUF, 0, 0x10000, 0xffffffff, PAGE_SIZE, 0ul);
542 		dcons_init(dg.buf, dg.size, sc);
543 	}
544 
545 ok:
546 	dcons_buf = dg.buf;
547 
548 #if __FreeBSD_version < 502122
549 #if defined(DDB) && DCONS_FORCE_GDB
550 #if CONS_NODEV
551 	gdbconsdev.cn_arg = (void *)&sc[DCONS_GDB];
552 #if __FreeBSD_version >= 501109
553 	sprintf(gdbconsdev.cn_name, "dgdb");
554 #endif
555 	gdb_arg = &gdbconsdev;
556 #elif defined(__DragonFly__)
557 	gdbdev = make_dev(&dcons_cdevsw, DCONS_GDB,
558 	    UID_ROOT, GID_WHEEL, 0600, "dgdb");
559 #else
560 	gdbdev = makedev(CDEV_MAJOR, DCONS_GDB);
561 #endif
562 	gdb_getc = dcons_cngetc;
563 	gdb_putc = dcons_cnputc;
564 #endif
565 #endif
566 	drv_init = 1;
567 
568 	return 0;
569 }
570 
571 
572 static int
573 dcons_attach_port(int port, char *name, int flags)
574 {
575 	struct dcons_softc *dc;
576 	struct tty *tp;
577 	DEV dev;
578 
579 	dc = &sc[port];
580 	dc->flags = flags;
581 	dev = make_dev(&dcons_cdevsw, port,
582 			UID_ROOT, GID_WHEEL, 0600, name);
583 	dc->dev = (void *)dev;
584 	tp = ttyalloc();
585 
586 	dev->si_drv1 = (void *)dc;
587 	dev->si_tty = tp;
588 
589 	tp->t_oproc = dcons_tty_start;
590 	tp->t_param = dcons_tty_param;
591 	tp->t_stop = nottystop;
592 	tp->t_dev = dc->dev;
593 
594 	return(0);
595 }
596 
597 static int
598 dcons_attach(void)
599 {
600 	int polltime;
601 
602 #ifdef __DragonFly__
603 	cdevsw_add(&dcons_cdevsw, -1, 0);
604 #endif
605 	dcons_attach_port(DCONS_CON, "dcons", 0);
606 	dcons_attach_port(DCONS_GDB, "dgdb", DC_GDB);
607 #if __FreeBSD_version < 500000
608 	callout_init(&dcons_callout);
609 #else
610 	callout_init(&dcons_callout, 0);
611 #endif
612 	polltime = hz / poll_hz;
613 	if (polltime < 1)
614 		polltime = 1;
615 	callout_reset(&dcons_callout, polltime, dcons_timeout, NULL);
616 	return(0);
617 }
618 
619 static int
620 dcons_detach(int port)
621 {
622 	struct	tty *tp;
623 	struct dcons_softc *dc;
624 
625 	dc = &sc[port];
626 
627 	tp = ((DEV)dc->dev)->si_tty;
628 
629 	if (tp->t_state & TS_ISOPEN) {
630 		printf("dcons: still opened\n");
631 #if __FreeBSD_version < 502113
632 		(*linesw[tp->t_line].l_close)(tp, 0);
633 		tp->t_gen++;
634 		ttyclose(tp);
635 		ttwakeup(tp);
636 		ttwwakeup(tp);
637 #else
638 		ttyld_close(tp, 0);
639 		tty_close(tp);
640 #endif
641 	}
642 	/* XXX
643 	 * must wait until all device are closed.
644 	 */
645 #ifdef __DragonFly__
646 	tsleep((void *)dc, 0, "dcodtc", hz/4);
647 #else
648 	tsleep((void *)dc, PWAIT, "dcodtc", hz/4);
649 #endif
650 	destroy_dev(dc->dev);
651 
652 	return(0);
653 }
654 
655 
656 /* cnXXX works only for FreeBSD-5 */
657 static int
658 dcons_modevent(module_t mode, int type, void *data)
659 {
660 	int err = 0, ret;
661 
662 	switch (type) {
663 	case MOD_LOAD:
664 		ret = dcons_drv_init(1);
665 		dcons_attach();
666 #if __FreeBSD_version >= 500000
667 		if (ret == 0) {
668 			dcons_cnprobe(&dcons_consdev);
669 			dcons_cninit(&dcons_consdev);
670 			cnadd(&dcons_consdev);
671 		}
672 #endif
673 		break;
674 	case MOD_UNLOAD:
675 		printf("dcons: unload\n");
676 		callout_stop(&dcons_callout);
677 #if __FreeBSD_version < 502122
678 #if defined(DDB) && DCONS_FORCE_GDB
679 #if CONS_NODEV
680 		gdb_arg = NULL;
681 #else
682 		gdbdev = NULL;
683 #endif
684 #endif
685 #endif
686 #if __FreeBSD_version >= 500000
687 		cnremove(&dcons_consdev);
688 #endif
689 		dcons_detach(DCONS_CON);
690 		dcons_detach(DCONS_GDB);
691 		dg.buf->magic = 0;
692 
693 		contigfree(dg.buf, DCONS_BUF_SIZE, M_DEVBUF);
694 
695 		break;
696 	case MOD_SHUTDOWN:
697 		dg.buf->magic = 0;
698 		break;
699 	default:
700 		err = EOPNOTSUPP;
701 		break;
702 	}
703 	return(err);
704 }
705 
706 #if __FreeBSD_version >= 502122
707 /* Debugger interface */
708 
709 static int
710 dcons_dbg_probe(void)
711 {
712 	return(DCONS_FORCE_GDB);
713 }
714 
715 static void
716 dcons_dbg_init(void)
717 {
718 }
719 
720 static void
721 dcons_dbg_term(void)
722 {
723 }
724 
725 static void
726 dcons_dbg_putc(int c)
727 {
728 	struct dcons_softc *dc = &sc[DCONS_GDB];
729 	dcons_os_putc(dc, c);
730 }
731 
732 static int
733 dcons_dbg_getc(void)
734 {
735 	struct dcons_softc *dc = &sc[DCONS_GDB];
736 	return (dcons_os_getc(dc));
737 }
738 #endif
739 
740 DEV_MODULE(dcons, dcons_modevent, NULL);
741 MODULE_VERSION(dcons, DCONS_VERSION);
742