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lunafb.c revision 1.30.2.1
      1 /* $NetBSD: lunafb.c,v 1.30.2.1 2014/08/10 06:54:00 tls 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 1.30.2.1 2014/08/10 06:54:00 tls 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	0xB1000000	/* video h-origin/v-origin */
     78 #define	OMFB_PLANEMASK	0xB1040000	/* planemask register */
     79 #define	OMFB_FB_WADDR	0xB1080008	/* common plane */
     80 #define	OMFB_FB_RADDR	0xB10C0008	/* plane #0 */
     81 #define	OMFB_ROPFUNC	0xB12C0000	/* ROP function code */
     82 #define	OMFB_RAMDAC	0xC1100000	/* Bt454/Bt458 RAMDAC */
     83 #define	OMFB_SIZE	(0xB1300000 - 0xB1080000 + PAGE_SIZE)
     84 
     85 struct hwcmap {
     86 #define CMAP_SIZE 256
     87 	uint8_t r[CMAP_SIZE];
     88 	uint8_t g[CMAP_SIZE];
     89 	uint8_t b[CMAP_SIZE];
     90 };
     91 
     92 static const struct {
     93 	uint8_t r;
     94 	uint8_t g;
     95 	uint8_t b;
     96 } ansicmap[16] = {
     97 	{    0,    0,    0},
     98 	{ 0x80,    0,    0},
     99 	{    0, 0x80,    0},
    100 	{ 0x80, 0x80,    0},
    101 	{    0,    0, 0x80},
    102 	{ 0x80,    0, 0x80},
    103 	{    0, 0x80, 0x80},
    104 	{ 0xc0, 0xc0, 0xc0},
    105 	{ 0x80, 0x80, 0x80},
    106 	{ 0xff,    0,    0},
    107 	{    0, 0xff,    0},
    108 	{ 0xff, 0xff,    0},
    109 	{    0,    0, 0xff},
    110 	{ 0xff,    0, 0xff},
    111 	{    0, 0xff, 0xff},
    112 	{ 0xff, 0xff, 0xff},
    113 };
    114 
    115 struct om_hwdevconfig {
    116 	int	dc_wid;			/* width of frame buffer */
    117 	int	dc_ht;			/* height of frame buffer */
    118 	int	dc_depth;		/* depth, bits per pixel */
    119 	int	dc_rowbytes;		/* bytes in a FB scan line */
    120 	int	dc_cmsize;		/* colormap size */
    121 	struct hwcmap dc_cmap;		/* software copy of colormap */
    122 	vaddr_t	dc_videobase;		/* base of flat frame buffer */
    123 	struct rasops_info dc_ri;	/* raster blitter variables */
    124 };
    125 
    126 struct omfb_softc {
    127 	device_t sc_dev;		/* base device */
    128 	struct om_hwdevconfig *sc_dc;	/* device configuration */
    129 	int sc_nscreens;
    130 	int sc_mode;
    131 };
    132 
    133 static int  omgetcmap(struct omfb_softc *, struct wsdisplay_cmap *);
    134 static int  omsetcmap(struct omfb_softc *, struct wsdisplay_cmap *);
    135 
    136 static struct om_hwdevconfig omfb_console_dc;
    137 static void omfb_resetcmap(struct om_hwdevconfig *);
    138 static void omfb_getdevconfig(paddr_t, struct om_hwdevconfig *);
    139 
    140 static struct wsscreen_descr omfb_stdscreen = {
    141 	.name = "std"
    142 };
    143 
    144 static const struct wsscreen_descr *_omfb_scrlist[] = {
    145 	&omfb_stdscreen,
    146 };
    147 
    148 static const struct wsscreen_list omfb_screenlist = {
    149 	sizeof(_omfb_scrlist) / sizeof(struct wsscreen_descr *), _omfb_scrlist
    150 };
    151 
    152 static int   omfbioctl(void *, void *, u_long, void *, int, struct lwp *);
    153 static paddr_t omfbmmap(void *, void *, off_t, int);
    154 static int   omfb_alloc_screen(void *, const struct wsscreen_descr *,
    155 			       void **, int *, int *, long *);
    156 static void  omfb_free_screen(void *, void *);
    157 static int   omfb_show_screen(void *, void *, int,
    158 			      void (*) (void *, int, int), void *);
    159 
    160 static const struct wsdisplay_accessops omfb_accessops = {
    161 	.ioctl        = omfbioctl,
    162 	.mmap         = omfbmmap,
    163 	.alloc_screen = omfb_alloc_screen,
    164 	.free_screen  = omfb_free_screen,
    165 	.show_screen  = omfb_show_screen,
    166 	.load_font    = NULL,
    167 	.pollc        = NULL,
    168 	.scroll       = NULL
    169 };
    170 
    171 static int  omfbmatch(device_t, cfdata_t, void *);
    172 static void omfbattach(device_t, device_t, void *);
    173 
    174 CFATTACH_DECL_NEW(fb, sizeof(struct omfb_softc),
    175     omfbmatch, omfbattach, NULL, NULL);
    176 
    177 extern int hwplanemask;	/* hardware planemask; retrieved at boot */
    178 
    179 static int omfb_console;
    180 int  omfb_cnattach(void);
    181 
    182 static int
    183 omfbmatch(device_t parent, cfdata_t cf, void *aux)
    184 {
    185 	struct mainbus_attach_args *ma = aux;
    186 
    187 	if (strcmp(ma->ma_name, fb_cd.cd_name))
    188 		return 0;
    189 #if 0	/* XXX badaddr() bombs if no framebuffer is installed */
    190 	if (badaddr((void *)ma->ma_addr, 4))
    191 		return 0;
    192 #else
    193 	if (hwplanemask == 0)
    194 		return 0;
    195 #endif
    196 	return 1;
    197 }
    198 
    199 static void
    200 omfbattach(device_t parent, device_t self, void *args)
    201 {
    202 	struct omfb_softc *sc = device_private(self);
    203 	struct wsemuldisplaydev_attach_args waa;
    204 
    205 	sc->sc_dev = self;
    206 
    207 	if (omfb_console) {
    208 		sc->sc_dc = &omfb_console_dc;
    209 		sc->sc_nscreens = 1;
    210 	} else {
    211 		sc->sc_dc = kmem_zalloc(sizeof(struct om_hwdevconfig),
    212 		    KM_SLEEP);
    213 		omfb_getdevconfig(OMFB_FB_WADDR, sc->sc_dc);
    214 	}
    215 	aprint_normal(": %d x %d, %dbpp\n", sc->sc_dc->dc_wid, sc->sc_dc->dc_ht,
    216 	    sc->sc_dc->dc_depth);
    217 
    218 	sc->sc_mode = WSDISPLAYIO_MODE_EMUL;
    219 	waa.console = omfb_console;
    220 	waa.scrdata = &omfb_screenlist;
    221 	waa.accessops = &omfb_accessops;
    222 	waa.accesscookie = sc;
    223 
    224 	config_found(self, &waa, wsemuldisplaydevprint);
    225 }
    226 
    227 /* EXPORT */ int
    228 omfb_cnattach(void)
    229 {
    230 	struct om_hwdevconfig *dc = &omfb_console_dc;
    231 	struct rasops_info *ri = &dc->dc_ri;
    232 	long defattr;
    233 
    234 	omfb_getdevconfig(OMFB_FB_WADDR, dc);
    235 	(*ri->ri_ops.allocattr)(ri, 0, 0, 0, &defattr);
    236 	wsdisplay_cnattach(&omfb_stdscreen, ri, 0, 0, defattr);
    237 	omfb_console = 1;
    238 	return 0;
    239 }
    240 
    241 static int
    242 omfbioctl(void *v, void *vs, u_long cmd, void *data, int flag, struct lwp *l)
    243 {
    244 	struct omfb_softc *sc = v;
    245 	struct om_hwdevconfig *dc = sc->sc_dc;
    246 	int new_mode;
    247 
    248 	switch (cmd) {
    249 	case WSDISPLAYIO_GTYPE:
    250 		*(u_int *)data = WSDISPLAY_TYPE_LUNA;
    251 		return 0;
    252 
    253 	case WSDISPLAYIO_GINFO:
    254 #define	wsd_fbip ((struct wsdisplay_fbinfo *)data)
    255 		wsd_fbip->height = dc->dc_ht;
    256 		wsd_fbip->width = dc->dc_wid;
    257 		wsd_fbip->depth = dc->dc_depth;
    258 		wsd_fbip->cmsize = dc->dc_cmsize;
    259 #undef fbt
    260 		return 0;
    261 
    262 	case WSDISPLAYIO_LINEBYTES:
    263 		*(u_int *)data = dc->dc_rowbytes;
    264 		return 0;
    265 
    266 	case WSDISPLAYIO_GETCMAP:
    267 		return omgetcmap(sc, (struct wsdisplay_cmap *)data);
    268 
    269 	case WSDISPLAYIO_PUTCMAP:
    270 		return omsetcmap(sc, (struct wsdisplay_cmap *)data);
    271 
    272 	case WSDISPLAYIO_SMODE:
    273 		new_mode = *(int *)data;
    274 		if (new_mode != sc->sc_mode) {
    275 			sc->sc_mode = new_mode;
    276 			if (new_mode == WSDISPLAYIO_MODE_EMUL)
    277 				omfb_resetcmap(dc);
    278 		}
    279 		return 0;
    280 
    281 	case WSDISPLAYIO_SVIDEO:
    282 	case WSDISPLAYIO_GVIDEO:
    283 	case WSDISPLAYIO_GCURPOS:
    284 	case WSDISPLAYIO_SCURPOS:
    285 	case WSDISPLAYIO_GCURMAX:
    286 	case WSDISPLAYIO_GCURSOR:
    287 	case WSDISPLAYIO_SCURSOR:
    288 		break;
    289 	}
    290 	return EPASSTHROUGH;
    291 }
    292 
    293 /*
    294  * Return the address that would map the given device at the given
    295  * offset, allowing for the given protection, or return -1 for error.
    296  */
    297 static paddr_t
    298 omfbmmap(void *v, void *vs, off_t offset, int prot)
    299 {
    300 	struct omfb_softc *sc = v;
    301 	struct om_hwdevconfig *dc = sc->sc_dc;
    302 	paddr_t cookie = -1;
    303 
    304 	switch (sc->sc_mode) {
    305 #if 0
    306 	case WSDISPLAYIO_MODE_MAPPED:
    307 		if (offset >= 0 && offset < OMFB_SIZE)
    308 			cookie = m68k_btop(m68k_trunc_page(dc->dc_videobase) +
    309 			    offset);
    310 		break;
    311 #endif
    312 	case WSDISPLAYIO_MODE_DUMBFB:
    313 		if (offset >= 0 &&
    314 		    offset < 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
    324 omgetcmap(struct omfb_softc *sc, struct wsdisplay_cmap *p)
    325 {
    326 	u_int index = p->index, count = p->count;
    327 	int cmsize, error;
    328 
    329 	cmsize = sc->sc_dc->dc_cmsize;
    330 	if (index >= cmsize || count > cmsize - index)
    331 		return EINVAL;
    332 
    333 	error = copyout(&sc->sc_dc->dc_cmap.r[index], p->red, count);
    334 	if (error)
    335 		return error;
    336 	error = copyout(&sc->sc_dc->dc_cmap.g[index], p->green, count);
    337 	if (error)
    338 		return error;
    339 	error = copyout(&sc->sc_dc->dc_cmap.b[index], p->blue, count);
    340 	return error;
    341 }
    342 
    343 static int
    344 omsetcmap(struct omfb_softc *sc, struct wsdisplay_cmap *p)
    345 {
    346 	struct hwcmap cmap;
    347 	u_int index = p->index, count = p->count;
    348 	int cmsize, i, error;
    349 
    350 	cmsize = sc->sc_dc->dc_cmsize;
    351 	if (index >= cmsize || (index + count) > cmsize)
    352 		return (EINVAL);
    353 
    354 	error = copyin(p->red, &cmap.r[index], count);
    355 	if (error)
    356 		return error;
    357 	error = copyin(p->green, &cmap.g[index], count);
    358 	if (error)
    359 		return error;
    360 	error = copyin(p->blue, &cmap.b[index], count);
    361 	if (error)
    362 		return error;
    363 
    364 	memcpy(&sc->sc_dc->dc_cmap.r[index], &cmap.r[index], count);
    365 	memcpy(&sc->sc_dc->dc_cmap.g[index], &cmap.g[index], count);
    366 	memcpy(&sc->sc_dc->dc_cmap.b[index], &cmap.b[index], count);
    367 	if (hwplanemask == 0x0f) {
    368 		struct bt454 *odac = (struct bt454 *)OMFB_RAMDAC;
    369 		odac->bt_addr = index;
    370 		for (i = index; i < index + count; i++) {
    371 			odac->bt_cmap = sc->sc_dc->dc_cmap.r[i];
    372 			odac->bt_cmap = sc->sc_dc->dc_cmap.g[i];
    373 			odac->bt_cmap = sc->sc_dc->dc_cmap.b[i];
    374 		}
    375 	} else if (hwplanemask == 0xff) {
    376 		struct bt458 *ndac = (struct bt458 *)OMFB_RAMDAC;
    377 		ndac->bt_addr = index;
    378 		for (i = index; i < index + count; i++) {
    379 			ndac->bt_cmap = sc->sc_dc->dc_cmap.r[i];
    380 			ndac->bt_cmap = sc->sc_dc->dc_cmap.g[i];
    381 			ndac->bt_cmap = sc->sc_dc->dc_cmap.b[i];
    382 		}
    383 	}
    384 	return 0;
    385 }
    386 
    387 static void
    388 omfb_resetcmap(struct om_hwdevconfig *dc)
    389 {
    390 	int i;
    391 
    392 	if (hwplanemask == 0x01) {
    393 		struct bt454 *odac = (struct bt454 *)OMFB_RAMDAC;
    394 
    395 		/*
    396 		 * On 1bpp framebuffer, only plane P0 has framebuffer memory
    397 		 * and other planes seems pulled up, i.e. always 1.
    398 		 * Set white only for a palette (P0,P1,P2,P3) = (1,1,1,1).
    399 		 */
    400 		odac->bt_addr = 0;
    401 		for (i = 0; i < 15; i++) {
    402 			odac->bt_cmap = dc->dc_cmap.r[i] = 0;
    403 			odac->bt_cmap = dc->dc_cmap.g[i] = 0;
    404 			odac->bt_cmap = dc->dc_cmap.b[i] = 0;
    405 		}
    406 		/*
    407 		 * The B/W video connector is connected to IOG of Bt454,
    408 		 * and IOR and IOB are unused.
    409 		 */
    410 		odac->bt_cmap = dc->dc_cmap.r[15] = 0;
    411 		odac->bt_cmap = dc->dc_cmap.g[15] = 255;
    412 		odac->bt_cmap = dc->dc_cmap.b[15] = 0;
    413 	} else if (hwplanemask == 0x0f) {
    414 		struct bt454 *odac = (struct bt454 *)OMFB_RAMDAC;
    415 
    416 		odac->bt_addr = 0;
    417 		for (i = 0; i < 16; i++) {
    418 			odac->bt_cmap = dc->dc_cmap.r[i] = ansicmap[i].r;
    419 			odac->bt_cmap = dc->dc_cmap.g[i] = ansicmap[i].g;
    420 			odac->bt_cmap = dc->dc_cmap.b[i] = ansicmap[i].b;
    421 		}
    422 	} else if (hwplanemask == 0xff) {
    423 		struct bt458 *ndac = (struct bt458 *)OMFB_RAMDAC;
    424 
    425 		/*
    426 		 * Initialize the Bt458.  When we write to control registers,
    427 		 * the address is not incremented automatically. So we specify
    428 		 * it ourselves for each control register.
    429 		 */
    430 		ndac->bt_addr = 0x04;
    431 		ndac->bt_ctrl = 0xff; /* all planes will be read */
    432 		ndac->bt_addr = 0x05;
    433 		ndac->bt_ctrl = 0x00; /* all planes have non-blink */
    434 		ndac->bt_addr = 0x06;
    435 		ndac->bt_ctrl = 0x40; /* pallete enabled, ovly plane disabled */
    436 		ndac->bt_addr = 0x07;
    437 		ndac->bt_ctrl = 0x00; /* no test mode */
    438 
    439 		/*
    440 		 * Set ANSI 16 colors.  We only supports 4bpp console right
    441 		 * now, repeat 16 colors in 256 colormap.
    442 		 */
    443 		ndac->bt_addr = 0;
    444 		for (i = 0; i < 256; i++) {
    445 			ndac->bt_cmap = dc->dc_cmap.r[i] = ansicmap[i % 16].r;
    446 			ndac->bt_cmap = dc->dc_cmap.g[i] = ansicmap[i % 16].g;
    447 			ndac->bt_cmap = dc->dc_cmap.b[i] = ansicmap[i % 16].b;
    448 		}
    449 	}
    450 }
    451 
    452 static void
    453 omfb_getdevconfig(paddr_t paddr, struct om_hwdevconfig *dc)
    454 {
    455 	int bpp, i;
    456 	struct rasops_info *ri;
    457 	union {
    458 		struct { short h, v; } p;
    459 		uint32_t u;
    460 	} rfcnt;
    461 
    462 	switch (hwplanemask) {
    463 	case 0xff:
    464 		bpp = 8;	/* XXX check monochrome bit in DIPSW */
    465 		break;
    466 	default:
    467 	case 0x0f:
    468 		bpp = 4;	/* XXX check monochrome bit in DIPSW */
    469 		break;
    470 	case 1:
    471 		bpp = 1;
    472 		break;
    473 	}
    474 	dc->dc_wid = 1280;
    475 	dc->dc_ht = 1024;
    476 	dc->dc_depth = bpp;
    477 	dc->dc_rowbytes = 2048 / 8;
    478 	dc->dc_cmsize = (bpp == 1) ? 0 : 1 << bpp;
    479 	dc->dc_videobase = paddr;
    480 
    481 	omfb_resetcmap(dc);
    482 
    483 	/* adjust h/v origin on screen */
    484 	rfcnt.p.h = 7;
    485 	rfcnt.p.v = -27;
    486 	/* single write of 0x007ffe6 */
    487 	*(volatile uint32_t *)OMFB_RFCNT = rfcnt.u;
    488 
    489 	/* clear the screen */
    490 	*(volatile uint32_t *)OMFB_PLANEMASK = 0xff;
    491 	((volatile uint32_t *)OMFB_ROPFUNC)[5] = ~0;	/* ROP copy */
    492 	for (i = 0; i < dc->dc_ht * dc->dc_rowbytes / sizeof(uint32_t); i++)
    493 		*((volatile uint32_t *)dc->dc_videobase + i) = 0;
    494 	*(volatile uint32_t *)OMFB_PLANEMASK = 0x01;
    495 
    496 	/* initialize the raster */
    497 	ri = &dc->dc_ri;
    498 	ri->ri_width = dc->dc_wid;
    499 	ri->ri_height = dc->dc_ht;
    500 	ri->ri_depth = 1;       /* since planes are independently addressed */
    501 	ri->ri_stride = dc->dc_rowbytes;
    502 	ri->ri_bits = (void *)dc->dc_videobase;
    503 	ri->ri_flg = RI_CENTER;
    504 	if (dc == &omfb_console_dc)
    505 		ri->ri_flg |= RI_NO_AUTO;
    506 	ri->ri_hw = dc;
    507 
    508 	if (bpp == 4 || bpp == 8)
    509 		omrasops4_init(ri, 34, 80);
    510 	else
    511 		omrasops1_init(ri, 34, 80);
    512 
    513 	omfb_stdscreen.nrows = ri->ri_rows;
    514 	omfb_stdscreen.ncols = ri->ri_cols;
    515 	omfb_stdscreen.textops = &ri->ri_ops;
    516 	omfb_stdscreen.capabilities = ri->ri_caps;
    517 	omfb_stdscreen.fontwidth = ri->ri_font->fontwidth;
    518 	omfb_stdscreen.fontheight = ri->ri_font->fontheight;
    519 }
    520 
    521 static int
    522 omfb_alloc_screen(void *v, const struct wsscreen_descr *type, void **cookiep,
    523     int *curxp, int *curyp, long *attrp)
    524 {
    525 	struct omfb_softc *sc = v;
    526 	struct rasops_info *ri = &sc->sc_dc->dc_ri;
    527 
    528 	if (sc->sc_nscreens > 0)
    529 		return ENOMEM;
    530 
    531 	*cookiep = ri;
    532 	*curxp = 0;
    533 	*curyp = 0;
    534 	(*ri->ri_ops.allocattr)(ri, 0, 0, 0, attrp);
    535 	sc->sc_nscreens++;
    536 	return 0;
    537 }
    538 
    539 static void
    540 omfb_free_screen(void *v, void *cookie)
    541 {
    542 	struct omfb_softc *sc = v;
    543 
    544 	if (sc->sc_dc == &omfb_console_dc)
    545 		panic("omfb_free_screen: console");
    546 
    547 	sc->sc_nscreens--;
    548 }
    549 
    550 static int
    551 omfb_show_screen(void *v, void *cookie, int waitok,
    552     void (*cb)(void *, int, int), void *cbarg)
    553 {
    554 
    555 	return 0;
    556 }
    557