xref: /netbsd-src/sys/arch/luna68k/dev/lunafb.c (revision f466d0ae583ff3e2a46e3a04e8ad6d11902367df)
1 /* $NetBSD: lunafb.c,v 1.49 2022/10/03 17:42:35 tsutsui Exp $ */
2 
3 /*-
4  * Copyright (c) 2000 The NetBSD Foundation, Inc.
5  * All rights reserved.
6  *
7  * This code is derived from software contributed to The NetBSD Foundation
8  * by Tohru Nishimura.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29  * POSSIBILITY OF SUCH DAMAGE.
30  */
31 
32 #include <sys/cdefs.h>			/* RCS ID & Copyright macro defns */
33 
34 __KERNEL_RCSID(0, "$NetBSD: lunafb.c,v 1.49 2022/10/03 17:42:35 tsutsui Exp $");
35 
36 #include <sys/param.h>
37 #include <sys/systm.h>
38 #include <sys/conf.h>
39 #include <sys/device.h>
40 #include <sys/ioctl.h>
41 #include <sys/kmem.h>
42 #include <sys/mman.h>
43 #include <sys/proc.h>
44 #include <sys/tty.h>
45 #include <sys/errno.h>
46 #include <sys/buf.h>
47 
48 #include <uvm/uvm_extern.h>
49 
50 #include <dev/wscons/wsconsio.h>
51 #include <dev/wscons/wsdisplayvar.h>
52 #include <dev/rasops/rasops.h>
53 
54 #include <machine/cpu.h>
55 #include <machine/autoconf.h>
56 
57 #include <arch/luna68k/dev/omrasopsvar.h>
58 
59 #include "ioconf.h"
60 
61 struct bt454 {
62 	volatile uint8_t bt_addr;	/* map address register */
63 	volatile uint8_t bt_cmap;	/* colormap data register */
64 };
65 
66 struct bt458 {
67 	volatile uint8_t bt_addr;	/* map address register */
68 	uint8_t          pad0[3];
69 	volatile uint8_t bt_cmap;	/* colormap data register */
70 	uint8_t          pad1[3];
71 	volatile uint8_t bt_ctrl;	/* control register */
72 	uint8_t          pad2[3];
73 	volatile uint8_t bt_omap;	/* overlay (cursor) map register */
74 	uint8_t          pad3[3];
75 };
76 
77 #define	OMFB_RFCNT	BMAP_RFCNT	/* video h-origin/v-origin */
78 #define	OMFB_RAMDAC	BMAP_PALLET2	/* Bt454/Bt458 RAMDAC */
79 #define	OMFB_FB_WADDR	(BMAP_BMP + 8)	/* common bitmap plane */
80 #define	OMFB_FB_RADDR	(BMAP_BMAP0 + 8)/* bitmap plane #0 */
81 
82 #define	OMFB_SIZE	(BMAP_FN0 - BMAP_BMP + PAGE_SIZE)
83 
84 struct hwcmap {
85 #define CMAP_SIZE 256
86 	uint8_t r[CMAP_SIZE];
87 	uint8_t g[CMAP_SIZE];
88 	uint8_t b[CMAP_SIZE];
89 };
90 
91 static const struct {
92 	uint8_t r;
93 	uint8_t g;
94 	uint8_t b;
95 } ansicmap[16] = {
96 	{    0,    0,    0},
97 	{ 0x80,    0,    0},
98 	{    0, 0x80,    0},
99 	{ 0x80, 0x80,    0},
100 	{    0,    0, 0x80},
101 	{ 0x80,    0, 0x80},
102 	{    0, 0x80, 0x80},
103 	{ 0xc0, 0xc0, 0xc0},
104 	{ 0x80, 0x80, 0x80},
105 	{ 0xff,    0,    0},
106 	{    0, 0xff,    0},
107 	{ 0xff, 0xff,    0},
108 	{    0,    0, 0xff},
109 	{ 0xff,    0, 0xff},
110 	{    0, 0xff, 0xff},
111 	{ 0xff, 0xff, 0xff},
112 };
113 
114 struct om_hwdevconfig {
115 	int	dc_wid;			/* width of frame buffer */
116 	int	dc_ht;			/* height of frame buffer */
117 	int	dc_depth;		/* depth, bits per pixel */
118 	int	dc_rowbytes;		/* bytes in a FB scan line */
119 	int	dc_cmsize;		/* colormap size */
120 	struct hwcmap dc_cmap;		/* software copy of colormap */
121 	vaddr_t	dc_videobase;		/* base of flat frame buffer */
122 	struct rasops_info dc_ri;	/* raster blitter variables */
123 };
124 
125 struct omfb_softc {
126 	device_t sc_dev;		/* base device */
127 	struct om_hwdevconfig *sc_dc;	/* device configuration */
128 	int sc_nscreens;
129 	int sc_mode;
130 };
131 
132 static int  omgetcmap(struct omfb_softc *, struct wsdisplay_cmap *);
133 static int  omsetcmap(struct omfb_softc *, struct wsdisplay_cmap *);
134 
135 static struct om_hwdevconfig omfb_console_dc;
136 static void omfb_resetcmap(struct om_hwdevconfig *);
137 static void omfb_getdevconfig(paddr_t, struct om_hwdevconfig *);
138 
139 static struct wsscreen_descr omfb_stdscreen = {
140 	.name = "std"
141 };
142 
143 static const struct wsscreen_descr *_omfb_scrlist[] = {
144 	&omfb_stdscreen,
145 };
146 
147 static const struct wsscreen_list omfb_screenlist = {
148 	sizeof(_omfb_scrlist) / sizeof(struct wsscreen_descr *), _omfb_scrlist
149 };
150 
151 static int   omfbioctl(void *, void *, u_long, void *, int, struct lwp *);
152 static paddr_t omfbmmap(void *, void *, off_t, int);
153 static int   omfb_alloc_screen(void *, const struct wsscreen_descr *,
154 			       void **, int *, int *, long *);
155 static void  omfb_free_screen(void *, void *);
156 static int   omfb_show_screen(void *, void *, int,
157 			      void (*) (void *, int, int), void *);
158 
159 static const struct wsdisplay_accessops omfb_accessops = {
160 	.ioctl        = omfbioctl,
161 	.mmap         = omfbmmap,
162 	.alloc_screen = omfb_alloc_screen,
163 	.free_screen  = omfb_free_screen,
164 	.show_screen  = omfb_show_screen,
165 	.load_font    = NULL,
166 	.pollc        = NULL,
167 	.scroll       = NULL
168 };
169 
170 static int  omfbmatch(device_t, cfdata_t, void *);
171 static void omfbattach(device_t, device_t, void *);
172 
173 CFATTACH_DECL_NEW(fb, sizeof(struct omfb_softc),
174     omfbmatch, omfbattach, NULL, NULL);
175 
176 extern int hwplanemask;	/* hardware planemask; retrieved at boot */
177 
178 static int omfb_console;
179 int  omfb_cnattach(void);
180 
181 static int
omfbmatch(device_t parent,cfdata_t cf,void * aux)182 omfbmatch(device_t parent, cfdata_t cf, void *aux)
183 {
184 	struct mainbus_attach_args *ma = aux;
185 
186 	if (strcmp(ma->ma_name, fb_cd.cd_name))
187 		return 0;
188 #if 0	/* XXX badaddr() bombs if no framebuffer is installed */
189 	if (badaddr((void *)ma->ma_addr, 4))
190 		return 0;
191 #else
192 	if (hwplanemask == 0)
193 		return 0;
194 #endif
195 	return 1;
196 }
197 
198 static void
omfbattach(device_t parent,device_t self,void * args)199 omfbattach(device_t parent, device_t self, void *args)
200 {
201 	struct omfb_softc *sc = device_private(self);
202 	struct wsemuldisplaydev_attach_args waa;
203 
204 	sc->sc_dev = self;
205 
206 	if (omfb_console) {
207 		sc->sc_dc = &omfb_console_dc;
208 		sc->sc_nscreens = 1;
209 	} else {
210 		sc->sc_dc = kmem_zalloc(sizeof(struct om_hwdevconfig),
211 		    KM_SLEEP);
212 		omfb_getdevconfig(OMFB_FB_WADDR, sc->sc_dc);
213 	}
214 	aprint_normal(": %d x %d, %dbpp\n", sc->sc_dc->dc_wid, sc->sc_dc->dc_ht,
215 	    sc->sc_dc->dc_depth);
216 
217 	sc->sc_mode = WSDISPLAYIO_MODE_EMUL;
218 	waa.console = omfb_console;
219 	waa.scrdata = &omfb_screenlist;
220 	waa.accessops = &omfb_accessops;
221 	waa.accesscookie = sc;
222 
223 	config_found(self, &waa, wsemuldisplaydevprint, CFARGS_NONE);
224 }
225 
226 /* EXPORT */ int
omfb_cnattach(void)227 omfb_cnattach(void)
228 {
229 	struct om_hwdevconfig *dc = &omfb_console_dc;
230 	struct rasops_info *ri = &dc->dc_ri;
231 	long defattr;
232 
233 	omfb_getdevconfig(OMFB_FB_WADDR, dc);
234 	(*ri->ri_ops.allocattr)(ri, 0, 0, 0, &defattr);
235 	wsdisplay_cnattach(&omfb_stdscreen, ri, 0, 0, defattr);
236 	omfb_console = 1;
237 	return 0;
238 }
239 
240 static int
omfbioctl(void * v,void * vs,u_long cmd,void * data,int flag,struct lwp * l)241 omfbioctl(void *v, void *vs, u_long cmd, void *data, int flag, struct lwp *l)
242 {
243 	struct omfb_softc *sc = v;
244 	struct om_hwdevconfig *dc = sc->sc_dc;
245 	int new_mode;
246 
247 	switch (cmd) {
248 	case WSDISPLAYIO_GTYPE:
249 		*(u_int *)data = WSDISPLAY_TYPE_LUNA;
250 		return 0;
251 
252 	case WSDISPLAYIO_GINFO:
253 #define	wsd_fbip ((struct wsdisplay_fbinfo *)data)
254 		wsd_fbip->height = dc->dc_ht;
255 		wsd_fbip->width = dc->dc_wid;
256 		wsd_fbip->depth = dc->dc_depth;
257 		wsd_fbip->cmsize = dc->dc_cmsize;
258 #undef wsd_fbip
259 		return 0;
260 
261 	case WSDISPLAYIO_LINEBYTES:
262 		*(u_int *)data = dc->dc_rowbytes;
263 		return 0;
264 
265 	case WSDISPLAYIO_GETCMAP:
266 		return omgetcmap(sc, (struct wsdisplay_cmap *)data);
267 
268 	case WSDISPLAYIO_PUTCMAP:
269 		return omsetcmap(sc, (struct wsdisplay_cmap *)data);
270 
271 	case WSDISPLAYIO_SMODE:
272 		new_mode = *(int *)data;
273 		if (new_mode != sc->sc_mode) {
274 			sc->sc_mode = new_mode;
275 			if (new_mode == WSDISPLAYIO_MODE_EMUL)
276 				omfb_resetcmap(dc);
277 		}
278 		return 0;
279 
280 	case WSDISPLAYIO_SVIDEO:
281 	case WSDISPLAYIO_GVIDEO:
282 	case WSDISPLAYIO_GCURPOS:
283 	case WSDISPLAYIO_SCURPOS:
284 	case WSDISPLAYIO_GCURMAX:
285 	case WSDISPLAYIO_GCURSOR:
286 	case WSDISPLAYIO_SCURSOR:
287 		break;
288 	}
289 	return EPASSTHROUGH;
290 }
291 
292 /*
293  * Return the address that would map the given device at the given
294  * offset, allowing for the given protection, or return -1 for error.
295  */
296 static paddr_t
omfbmmap(void * v,void * vs,off_t offset,int prot)297 omfbmmap(void *v, void *vs, off_t offset, int prot)
298 {
299 	struct omfb_softc *sc = v;
300 	struct om_hwdevconfig *dc = sc->sc_dc;
301 	paddr_t cookie = -1;
302 
303 	switch (sc->sc_mode) {
304 #if 0
305 	case WSDISPLAYIO_MODE_MAPPED:
306 		if (offset >= 0 && offset < OMFB_SIZE)
307 			cookie = m68k_btop(m68k_trunc_page(dc->dc_videobase) +
308 			    offset);
309 		break;
310 #endif
311 	case WSDISPLAYIO_MODE_DUMBFB:
312 		if (offset >= 0 &&
313 		    offset < m68k_page_offset(OMFB_FB_RADDR) +
314 		    dc->dc_rowbytes * dc->dc_ht * dc->dc_depth)
315 			cookie = m68k_btop(m68k_trunc_page(OMFB_FB_RADDR) +
316 			    offset);
317 		break;
318 	}
319 
320 	return cookie;
321 }
322 
323 static int
omgetcmap(struct omfb_softc * sc,struct wsdisplay_cmap * p)324 omgetcmap(struct omfb_softc *sc, struct wsdisplay_cmap *p)
325 {
326 	u_int index = p->index, count = p->count;
327 	u_int cmsize;
328 	int error;
329 
330 	cmsize = sc->sc_dc->dc_cmsize;
331 	if (index >= cmsize || count > cmsize - index)
332 		return EINVAL;
333 
334 	error = copyout(&sc->sc_dc->dc_cmap.r[index], p->red, count);
335 	if (error != 0)
336 		return error;
337 	error = copyout(&sc->sc_dc->dc_cmap.g[index], p->green, count);
338 	if (error != 0)
339 		return error;
340 	error = copyout(&sc->sc_dc->dc_cmap.b[index], p->blue, count);
341 	if (error != 0)
342 		return error;
343 
344 	return 0;
345 }
346 
347 static int
omsetcmap(struct omfb_softc * sc,struct wsdisplay_cmap * p)348 omsetcmap(struct omfb_softc *sc, struct wsdisplay_cmap *p)
349 {
350 	struct hwcmap cmap;
351 	u_int index = p->index, count = p->count;
352 	u_int cmsize;
353 	int i, error;
354 
355 	cmsize = sc->sc_dc->dc_cmsize;
356 
357 	if (index >= cmsize || count > cmsize - index)
358 		return EINVAL;
359 
360 	error = copyin(p->red, &cmap.r[index], count);
361 	if (error != 0)
362 		return error;
363 	error = copyin(p->green, &cmap.g[index], count);
364 	if (error != 0)
365 		return error;
366 	error = copyin(p->blue, &cmap.b[index], count);
367 	if (error != 0)
368 		return error;
369 
370 	memcpy(&sc->sc_dc->dc_cmap.r[index], &cmap.r[index], count);
371 	memcpy(&sc->sc_dc->dc_cmap.g[index], &cmap.g[index], count);
372 	memcpy(&sc->sc_dc->dc_cmap.b[index], &cmap.b[index], count);
373 	if (hwplanemask == 0x0f) {
374 		struct bt454 *odac = (struct bt454 *)OMFB_RAMDAC;
375 		odac->bt_addr = index;
376 		for (i = index; i < index + count; i++) {
377 			odac->bt_cmap = sc->sc_dc->dc_cmap.r[i];
378 			odac->bt_cmap = sc->sc_dc->dc_cmap.g[i];
379 			odac->bt_cmap = sc->sc_dc->dc_cmap.b[i];
380 		}
381 	} else if (hwplanemask == 0xff) {
382 		struct bt458 *ndac = (struct bt458 *)OMFB_RAMDAC;
383 		ndac->bt_addr = index;
384 		for (i = index; i < index + count; i++) {
385 			ndac->bt_cmap = sc->sc_dc->dc_cmap.r[i];
386 			ndac->bt_cmap = sc->sc_dc->dc_cmap.g[i];
387 			ndac->bt_cmap = sc->sc_dc->dc_cmap.b[i];
388 		}
389 	}
390 	return 0;
391 }
392 
393 static void
omfb_resetcmap(struct om_hwdevconfig * dc)394 omfb_resetcmap(struct om_hwdevconfig *dc)
395 {
396 	int i;
397 
398 	if (hwplanemask == 0x01) {
399 		struct bt454 *odac = (struct bt454 *)OMFB_RAMDAC;
400 
401 		/*
402 		 * On 1bpp framebuffer, only plane P0 has framebuffer memory
403 		 * and other planes seems pulled up, i.e. always 1.
404 		 * Set white only for a palette (P0,P1,P2,P3) = (1,1,1,1).
405 		 */
406 		odac->bt_addr = 0;
407 		for (i = 0; i < 15; i++) {
408 			odac->bt_cmap = dc->dc_cmap.r[i] = 0;
409 			odac->bt_cmap = dc->dc_cmap.g[i] = 0;
410 			odac->bt_cmap = dc->dc_cmap.b[i] = 0;
411 		}
412 		/*
413 		 * The B/W video connector is connected to IOG of Bt454,
414 		 * and IOR and IOB are unused.
415 		 */
416 		odac->bt_cmap = dc->dc_cmap.r[15] = 0;
417 		odac->bt_cmap = dc->dc_cmap.g[15] = 255;
418 		odac->bt_cmap = dc->dc_cmap.b[15] = 0;
419 	} else if (hwplanemask == 0x0f) {
420 		struct bt454 *odac = (struct bt454 *)OMFB_RAMDAC;
421 
422 		odac->bt_addr = 0;
423 		for (i = 0; i < 16; i++) {
424 			odac->bt_cmap = dc->dc_cmap.r[i] = ansicmap[i].r;
425 			odac->bt_cmap = dc->dc_cmap.g[i] = ansicmap[i].g;
426 			odac->bt_cmap = dc->dc_cmap.b[i] = ansicmap[i].b;
427 		}
428 	} else if (hwplanemask == 0xff) {
429 		struct bt458 *ndac = (struct bt458 *)OMFB_RAMDAC;
430 
431 		/*
432 		 * Initialize the Bt458.  When we write to control registers,
433 		 * the address is not incremented automatically. So we specify
434 		 * it ourselves for each control register.
435 		 */
436 		ndac->bt_addr = 0x04;
437 		ndac->bt_ctrl = 0xff; /* all planes will be read */
438 		ndac->bt_addr = 0x05;
439 		ndac->bt_ctrl = 0x00; /* all planes have non-blink */
440 		ndac->bt_addr = 0x06;
441 		ndac->bt_ctrl = 0x40; /* palette enabled, ovly plane disabled */
442 		ndac->bt_addr = 0x07;
443 		ndac->bt_ctrl = 0x00; /* no test mode */
444 
445 		/*
446 		 * Set ANSI 16 colors.  We only supports 4bpp console right
447 		 * now, repeat 16 colors in 256 colormap.
448 		 */
449 		ndac->bt_addr = 0;
450 		for (i = 0; i < 256; i++) {
451 			ndac->bt_cmap = dc->dc_cmap.r[i] = ansicmap[i % 16].r;
452 			ndac->bt_cmap = dc->dc_cmap.g[i] = ansicmap[i % 16].g;
453 			ndac->bt_cmap = dc->dc_cmap.b[i] = ansicmap[i % 16].b;
454 		}
455 	}
456 }
457 
458 static void
omfb_getdevconfig(paddr_t paddr,struct om_hwdevconfig * dc)459 omfb_getdevconfig(paddr_t paddr, struct om_hwdevconfig *dc)
460 {
461 	int bpp, i;
462 	struct rasops_info *ri;
463 	union {
464 		struct { short h, v; } p;
465 		uint32_t u;
466 	} rfcnt;
467 
468 	switch (hwplanemask) {
469 	case 0xff:
470 		bpp = 8;	/* XXX check monochrome bit in DIPSW */
471 		break;
472 	default:
473 	case 0x0f:
474 		bpp = 4;	/* XXX check monochrome bit in DIPSW */
475 		break;
476 	case 1:
477 		bpp = 1;
478 		break;
479 	}
480 	dc->dc_wid = 1280;
481 	dc->dc_ht = 1024;
482 	dc->dc_depth = bpp;
483 	dc->dc_rowbytes = 2048 / 8;
484 	dc->dc_cmsize = (bpp == 1) ? 0 : 1 << bpp;
485 	dc->dc_videobase = paddr;
486 
487 	omfb_resetcmap(dc);
488 
489 	/* adjust h/v origin on screen */
490 	rfcnt.p.h = 7;
491 	rfcnt.p.v = -27;
492 	/* single write of 0x007ffe6 */
493 	*(volatile uint32_t *)OMFB_RFCNT = rfcnt.u;
494 
495 	/* clear the screen */
496 	*(volatile uint32_t *)OMFB_PLANEMASK = 0xff;
497 	((volatile uint32_t *)OMFB_ROPFUNC)[5] = ~0;	/* ROP copy */
498 	for (i = 0; i < dc->dc_ht * dc->dc_rowbytes / sizeof(uint32_t); i++)
499 		*((volatile uint32_t *)dc->dc_videobase + i) = 0;
500 	*(volatile uint32_t *)OMFB_PLANEMASK = 0x01;
501 
502 	/* initialize the raster */
503 	ri = &dc->dc_ri;
504 	ri->ri_width = dc->dc_wid;
505 	ri->ri_height = dc->dc_ht;
506 	ri->ri_depth = dc->dc_depth;
507 	ri->ri_stride = dc->dc_rowbytes;
508 	ri->ri_bits = (void *)dc->dc_videobase;
509 	ri->ri_flg = RI_CENTER;
510 	if (dc == &omfb_console_dc)
511 		ri->ri_flg |= RI_NO_AUTO;
512 	ri->ri_hw = dc;
513 
514 	if (bpp == 4 || bpp == 8)
515 		omrasops4_init(ri, 34, 80);
516 	else
517 		omrasops1_init(ri, 34, 80);
518 
519 	omfb_stdscreen.nrows = ri->ri_rows;
520 	omfb_stdscreen.ncols = ri->ri_cols;
521 	omfb_stdscreen.textops = &ri->ri_ops;
522 	omfb_stdscreen.capabilities = ri->ri_caps;
523 	omfb_stdscreen.fontwidth = ri->ri_font->fontwidth;
524 	omfb_stdscreen.fontheight = ri->ri_font->fontheight;
525 }
526 
527 static int
omfb_alloc_screen(void * v,const struct wsscreen_descr * type,void ** cookiep,int * curxp,int * curyp,long * attrp)528 omfb_alloc_screen(void *v, const struct wsscreen_descr *type, void **cookiep,
529     int *curxp, int *curyp, long *attrp)
530 {
531 	struct omfb_softc *sc = v;
532 	struct rasops_info *ri = &sc->sc_dc->dc_ri;
533 
534 	if (sc->sc_nscreens > 0)
535 		return ENOMEM;
536 
537 	*cookiep = ri;
538 	*curxp = 0;
539 	*curyp = 0;
540 	(*ri->ri_ops.allocattr)(ri, 0, 0, 0, attrp);
541 	sc->sc_nscreens++;
542 	return 0;
543 }
544 
545 static void
omfb_free_screen(void * v,void * cookie)546 omfb_free_screen(void *v, void *cookie)
547 {
548 	struct omfb_softc *sc = v;
549 
550 	if (sc->sc_dc == &omfb_console_dc)
551 		panic("omfb_free_screen: console");
552 
553 	sc->sc_nscreens--;
554 }
555 
556 static int
omfb_show_screen(void * v,void * cookie,int waitok,void (* cb)(void *,int,int),void * cbarg)557 omfb_show_screen(void *v, void *cookie, int waitok,
558     void (*cb)(void *, int, int), void *cbarg)
559 {
560 
561 	return 0;
562 }
563