xref: /src/sys/arch/sparc64/dev/ffb.c

/*	$NetBSD: ffb.c,v 1.13 2005/05/15 16:41:25 martin Exp $	*/
/*	$OpenBSD: creator.c,v 1.20 2002/07/30 19:48:15 jason Exp $	*/

/*
 * Copyright (c) 2002 Jason L. Wright (jason (at) thought.net)
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by Jason L. Wright
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: ffb.c,v 1.13 2005/05/15 16:41:25 martin Exp $");

#include <sys/types.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/device.h>
#include <sys/conf.h>

#include <machine/bus.h>
#include <machine/autoconf.h>
#include <machine/openfirm.h>
#include <machine/vmparam.h>

#include <dev/wscons/wsconsio.h>
#include <dev/sun/fbio.h>
#include <dev/sun/fbvar.h>

#include <sparc64/dev/ffbreg.h>
#include <sparc64/dev/ffbvar.h>

extern struct cfdriver ffb_cd;

struct wsscreen_descr ffb_stdscreen = {
	"sunffb",
	0, 0,	/* will be filled in -- XXX shouldn't, it's global. */
	0,
	0, 0,
	WSSCREEN_REVERSE | WSSCREEN_WSCOLORS
};

const struct wsscreen_descr *ffb_scrlist[] = {
	&ffb_stdscreen,
	/* XXX other formats? */
};

struct wsscreen_list ffb_screenlist = {
	sizeof(ffb_scrlist) / sizeof(struct wsscreen_descr *),
	    ffb_scrlist
};

int	ffb_ioctl(void *, u_long, caddr_t, int, struct proc *);
int	ffb_alloc_screen(void *, const struct wsscreen_descr *, void **,
	    int *, int *, long *);
static int ffb_blank(struct ffb_softc *, u_long, u_int *);
void	ffb_free_screen(void *, void *);
int	ffb_show_screen(void *, void *, int, void (*cb)(void *, int, int),
	    void *);
paddr_t ffb_mmap(void *, off_t, int);
void	ffb_ras_fifo_wait(struct ffb_softc *, int);
void	ffb_ras_wait(struct ffb_softc *);
void	ffb_ras_init(struct ffb_softc *);
void	ffb_ras_copyrows(void *, int, int, int);
void	ffb_ras_erasecols(void *, int, int, int, long int);
void	ffb_ras_eraserows(void *, int, int, long int);
void	ffb_ras_do_cursor(struct rasops_info *);
void	ffb_ras_fill(struct ffb_softc *);
void	ffb_ras_setfg(struct ffb_softc *, int32_t);

/* frame buffer generic driver */
static void ffbfb_unblank(struct device*);
dev_type_open(ffbfb_open);
dev_type_close(ffbfb_close);
dev_type_ioctl(ffbfb_ioctl);
dev_type_mmap(ffbfb_mmap);
static struct fbdriver ffb_fbdriver = {
        ffbfb_unblank, ffbfb_open, ffbfb_close, ffbfb_ioctl, nopoll,
	ffbfb_mmap, nokqfilter
};

struct wsdisplay_accessops ffb_accessops = {
	ffb_ioctl,
	ffb_mmap,
	ffb_alloc_screen,
	ffb_free_screen,
	ffb_show_screen,
	NULL,	/* load font */
	NULL,	/* pollc */
	NULL,	/* getwschar */
	NULL,	/* putwschar */
	NULL,	/* scroll */
};

void
ffb_attach(struct ffb_softc *sc)
{
	struct wsemuldisplaydev_attach_args waa;
	char *model;
	int btype;
	int maxrow, maxcol;
	u_int blank = WSDISPLAYIO_VIDEO_ON;
	char buf[6+1];

	printf(":");

	if (sc->sc_type == FFB_CREATOR) {
		btype = prom_getpropint(sc->sc_node, "board_type", 0);
		if ((btype & 7) == 3)
			printf(" Creator3D");
		else
			printf(" Creator");
	} else
		printf(" Elite3D");

	model = prom_getpropstring(sc->sc_node, "model");
	if (model == NULL || strlen(model) == 0)
		model = "unknown";

	sc->sc_depth = 24;
	sc->sc_linebytes = 8192;
	sc->sc_height = prom_getpropint(sc->sc_node, "height", 0);
	sc->sc_width = prom_getpropint(sc->sc_node, "width", 0);

	sc->sc_fb.fb_rinfo.ri_depth = 32;
	sc->sc_fb.fb_rinfo.ri_stride = sc->sc_linebytes;
	sc->sc_fb.fb_rinfo.ri_flg = RI_CENTER;
	sc->sc_fb.fb_rinfo.ri_bits = (void *)bus_space_vaddr(sc->sc_bt,
	    sc->sc_pixel_h);

	sc->sc_fb.fb_rinfo.ri_width = sc->sc_width;
	sc->sc_fb.fb_rinfo.ri_height = sc->sc_height;
	sc->sc_fb.fb_rinfo.ri_hw = sc;

	maxcol = (prom_getoption("screen-#columns", buf, sizeof buf) == 0)
		? strtoul(buf, NULL, 10)
		: 80;

	maxrow = (prom_getoption("screen-#rows", buf, sizeof buf) != 0)
		? strtoul(buf, NULL, 10)
		: 34;

	rasops_init(&sc->sc_fb.fb_rinfo, maxrow, maxcol);

	if ((sc->sc_dv.dv_cfdata->cf_flags & FFB_CFFLAG_NOACCEL) == 0) {
		sc->sc_fb.fb_rinfo.ri_hw = sc;
		sc->sc_fb.fb_rinfo.ri_ops.eraserows = ffb_ras_eraserows;
		sc->sc_fb.fb_rinfo.ri_ops.erasecols = ffb_ras_erasecols;
		sc->sc_fb.fb_rinfo.ri_ops.copyrows = ffb_ras_copyrows;
		ffb_ras_init(sc);
	}

	ffb_stdscreen.nrows = sc->sc_fb.fb_rinfo.ri_rows;
	ffb_stdscreen.ncols = sc->sc_fb.fb_rinfo.ri_cols;
	ffb_stdscreen.textops = &sc->sc_fb.fb_rinfo.ri_ops;

	/* collect DAC version, as Elite3D cursor enable bit is reversed */
	DAC_WRITE(sc, FFB_DAC_TYPE, FFB_DAC_GVERS);
	sc->sc_dacrev = DAC_READ(sc, FFB_DAC_VALUE) >> 28;

	if (sc->sc_type == FFB_AFB)
		sc->sc_dacrev = 10;
	printf(", model %s, dac %u\n", model, sc->sc_dacrev);

	ffb_blank(sc, WSDISPLAYIO_SVIDEO, &blank);

	sc->sc_fb.fb_driver = &ffb_fbdriver;
	sc->sc_fb.fb_type.fb_cmsize = 0;
	sc->sc_fb.fb_type.fb_size = maxrow * sc->sc_linebytes;
	sc->sc_fb.fb_type.fb_type = FBTYPE_CREATOR;
	sc->sc_fb.fb_type.fb_width = sc->sc_width;
	sc->sc_fb.fb_type.fb_depth = sc->sc_depth;
	sc->sc_fb.fb_type.fb_height = sc->sc_height;
	sc->sc_fb.fb_device = &sc->sc_dv;
	fb_attach(&sc->sc_fb, sc->sc_console);

	if (sc->sc_console) {
		int *ccolp, *crowp;
		long defattr;

		if (romgetcursoraddr(&crowp, &ccolp))
			ccolp = crowp = NULL;
		if (ccolp != NULL)
			sc->sc_fb.fb_rinfo.ri_ccol = *ccolp;
		if (crowp != NULL)
			sc->sc_fb.fb_rinfo.ri_crow = *crowp;

		sc->sc_fb.fb_rinfo.ri_ops.allocattr(&sc->sc_fb.fb_rinfo,
		    0, 0, 0, &defattr);

		wsdisplay_cnattach(&ffb_stdscreen, &sc->sc_fb.fb_rinfo,
		    sc->sc_fb.fb_rinfo.ri_ccol, sc->sc_fb.fb_rinfo.ri_crow, defattr);
	}

	waa.console = sc->sc_console;
	waa.scrdata = &ffb_screenlist;
	waa.accessops = &ffb_accessops;
	waa.accesscookie = sc;
	config_found(&sc->sc_dv, &waa, wsemuldisplaydevprint);
}

int
ffb_ioctl(void *v, u_long cmd, caddr_t data, int flags, struct proc *p)
{
	struct ffb_softc *sc = v;
	struct wsdisplay_fbinfo *wdf;

#ifdef FFBDEBUG
	printf("ffb_ioctl: %s cmd _IO%s%s('%c', %lu)\n",
	       sc->sc_dv.dv_xname,
	       (cmd & IOC_IN) ? "W" : "", (cmd & IOC_OUT) ? "R" : "",
	       (char)IOCGROUP(cmd), cmd & 0xff);
#endif

	switch (cmd) {
	case FBIOGTYPE:
		*(struct fbtype *)data = sc->sc_fb.fb_type;
		break;
	case FBIOGATTR:
#define fba ((struct fbgattr *)data)
		fba->real_type = sc->sc_fb.fb_type.fb_type;
		fba->owner = 0; 	/* XXX ??? */
		fba->fbtype = sc->sc_fb.fb_type;
		fba->sattr.flags = 0;
		fba->sattr.emu_type = sc->sc_fb.fb_type.fb_type;
		fba->sattr.dev_specific[0] = -1;
		fba->emu_types[0] = sc->sc_fb.fb_type.fb_type;
		fba->emu_types[1] = -1;
#undef fba
		break;

	case FBIOGETCMAP:
	case FBIOPUTCMAP:
		return EIO;

	case FBIOGVIDEO:
	case FBIOSVIDEO:
		return ffb_blank(sc, cmd == FBIOGVIDEO?
		    WSDISPLAYIO_GVIDEO : WSDISPLAYIO_SVIDEO,
		    (u_int *)data);
		break;
	case FBIOGCURSOR:
	case FBIOSCURSOR:
		/* the console driver is not using the hardware cursor */
		break;
	case FBIOGCURPOS:
		printf("%s: FBIOGCURPOS not implemented\n", sc->sc_dv.dv_xname);
		return EIO;
	case FBIOSCURPOS:
		printf("%s: FBIOSCURPOS not implemented\n", sc->sc_dv.dv_xname);
		return EIO;
	case FBIOGCURMAX:
		printf("%s: FBIOGCURMAX not implemented\n", sc->sc_dv.dv_xname);
		return EIO;

	case WSDISPLAYIO_GTYPE:
		*(u_int *)data = WSDISPLAY_TYPE_SUNFFB;
		break;
	case WSDISPLAYIO_SMODE:
		sc->sc_mode = *(u_int *)data;
		break;
	case WSDISPLAYIO_GINFO:
		wdf = (void *)data;
		wdf->height = sc->sc_height;
		wdf->width  = sc->sc_width;
		wdf->depth  = 32;
		wdf->cmsize = 256; /* XXX */
		break;
#ifdef WSDISPLAYIO_LINEBYTES
	case WSDISPLAYIO_LINEBYTES:
		*(u_int *)data = sc->sc_linebytes;
		break;
#endif
	case WSDISPLAYIO_GETCMAP:
		break;/* XXX */

	case WSDISPLAYIO_PUTCMAP:
		break;/* XXX */

	case WSDISPLAYIO_SVIDEO:
	case WSDISPLAYIO_GVIDEO:
		return(ffb_blank(sc, cmd, (u_int *)data));
		break;
	case WSDISPLAYIO_GCURPOS:
	case WSDISPLAYIO_SCURPOS:
	case WSDISPLAYIO_GCURMAX:
	case WSDISPLAYIO_GCURSOR:
	case WSDISPLAYIO_SCURSOR:
		return EIO; /* not supported yet */
	default:
		return EPASSTHROUGH;
        }

	return (0);
}

int
ffb_alloc_screen(void *v, const struct wsscreen_descr *type, void **cookiep,
    int *curxp, int *curyp, long *attrp)
{
	struct ffb_softc *sc = v;

	if (sc->sc_nscreens > 0)
		return (ENOMEM);

	*cookiep = &sc->sc_fb.fb_rinfo;
	*curyp = 0;
	*curxp = 0;

	sc->sc_fb.fb_rinfo.ri_ops.allocattr(&sc->sc_fb.fb_rinfo, 0, 0, 0, attrp);

	sc->sc_nscreens++;
	return (0);
}

/* blank/unblank the screen */
static int
ffb_blank(struct ffb_softc *sc, u_long cmd, u_int *data)
{
	u_int val;

	DAC_WRITE(sc, FFB_DAC_TYPE, FFB_DAC_GSBLANK);
	val = DAC_READ(sc, FFB_DAC_VALUE);

	switch (cmd) {
	case WSDISPLAYIO_GVIDEO:
		*data = val & 1;
		return(0);
		break;
	case WSDISPLAYIO_SVIDEO:
		if (*data == WSDISPLAYIO_VIDEO_OFF)
			val &= ~1;
		else if (*data == WSDISPLAYIO_VIDEO_ON)
			val |= 1;
		else
			return(EINVAL);
		break;
	default:
		return(EINVAL);
	}

	DAC_WRITE(sc, FFB_DAC_TYPE, FFB_DAC_GSBLANK);
	DAC_WRITE(sc, FFB_DAC_VALUE, val);

	return(0);
}

void
ffb_free_screen(void *v, void *cookie)
{
	struct ffb_softc *sc = v;

	sc->sc_nscreens--;
}

int
ffb_show_screen(void *v, void *cookie, int waitok,
    void (*cb)(void *, int, int), void *cbarg)
{
	return (0);
}

paddr_t
ffb_mmap(void *vsc, off_t off, int prot)
{
	struct ffb_softc *sc = vsc;
	int i;

	switch (sc->sc_mode) {
	case WSDISPLAYIO_MODE_MAPPED:
		for (i = 0; i < sc->sc_nreg; i++) {
			/* Before this set? */
			if (off < sc->sc_addrs[i])
				continue;
			/* After this set? */
			if (off >= (sc->sc_addrs[i] + sc->sc_sizes[i]))
				continue;

			return (bus_space_mmap(sc->sc_bt, sc->sc_addrs[i],
			    off - sc->sc_addrs[i], prot, BUS_SPACE_MAP_LINEAR));
		}
		break;
#ifdef WSDISPLAYIO_MODE_DUMBFB
	case WSDISPLAYIO_MODE_DUMBFB:
		if (sc->sc_nreg < FFB_REG_DFB24)
			break;
		if (off >= 0 && off < sc->sc_sizes[FFB_REG_DFB24])
			return (bus_space_mmap(sc->sc_bt,
			    sc->sc_addrs[FFB_REG_DFB24], off, prot,
			    BUS_SPACE_MAP_LINEAR));
		break;
#endif
	}

	return (-1);
}

void
ffb_ras_fifo_wait(struct ffb_softc *sc, int n)
{
	int32_t cache = sc->sc_fifo_cache;

	if (cache < n) {
		do {
			cache = FBC_READ(sc, FFB_FBC_UCSR);
			cache = (cache & FBC_UCSR_FIFO_MASK) - 8;
		} while (cache < n);
	}
	sc->sc_fifo_cache = cache - n;
}

void
ffb_ras_wait(struct ffb_softc *sc)
{
	u_int32_t ucsr, r;

	while (1) {
		ucsr = FBC_READ(sc, FFB_FBC_UCSR);
		if ((ucsr & (FBC_UCSR_FB_BUSY|FBC_UCSR_RP_BUSY)) == 0)
			break;
		r = ucsr & (FBC_UCSR_READ_ERR | FBC_UCSR_FIFO_OVFL);
		if (r != 0)
			FBC_WRITE(sc, FFB_FBC_UCSR, r);
	}
}

void
ffb_ras_init(struct ffb_softc *sc)
{
	ffb_ras_fifo_wait(sc, 7);
	FBC_WRITE(sc, FFB_FBC_PPC,
	    FBC_PPC_VCE_DIS | FBC_PPC_TBE_OPAQUE |
	    FBC_PPC_APE_DIS | FBC_PPC_CS_CONST);
	FBC_WRITE(sc, FFB_FBC_FBC,
	    FFB_FBC_WB_A | FFB_FBC_RB_A | FFB_FBC_SB_BOTH |
	    FFB_FBC_XE_OFF | FFB_FBC_RGBE_MASK);
	FBC_WRITE(sc, FFB_FBC_ROP, FBC_ROP_NEW);
	FBC_WRITE(sc, FFB_FBC_DRAWOP, FBC_DRAWOP_RECTANGLE);
	FBC_WRITE(sc, FFB_FBC_PMASK, 0xffffffff);
	FBC_WRITE(sc, FFB_FBC_FONTINC, 0x10000);
	sc->sc_fg_cache = 0;
	FBC_WRITE(sc, FFB_FBC_FG, sc->sc_fg_cache);
	ffb_ras_wait(sc);
}

void
ffb_ras_eraserows(void *cookie, int row, int n, long attr)
{
	struct rasops_info *ri = cookie;
	struct ffb_softc *sc = ri->ri_hw;

	if (row < 0) {
		n += row;
		row = 0;
	}
	if (row + n > ri->ri_rows)
		n = ri->ri_rows - row;
	if (n <= 0)
		return;

	ffb_ras_fill(sc);
	ffb_ras_setfg(sc, ri->ri_devcmap[(attr >> 16) & 0xf]);
	ffb_ras_fifo_wait(sc, 4);
	if ((n == ri->ri_rows) && (ri->ri_flg & RI_FULLCLEAR)) {
		FBC_WRITE(sc, FFB_FBC_BY, 0);
		FBC_WRITE(sc, FFB_FBC_BX, 0);
		FBC_WRITE(sc, FFB_FBC_BH, ri->ri_height);
		FBC_WRITE(sc, FFB_FBC_BW, ri->ri_width);
	} else {
		row *= ri->ri_font->fontheight;
		FBC_WRITE(sc, FFB_FBC_BY, ri->ri_yorigin + row);
		FBC_WRITE(sc, FFB_FBC_BX, ri->ri_xorigin);
		FBC_WRITE(sc, FFB_FBC_BH, n * ri->ri_font->fontheight);
		FBC_WRITE(sc, FFB_FBC_BW, ri->ri_emuwidth);
	}
	ffb_ras_wait(sc);
}

void
ffb_ras_erasecols(void *cookie, int row, int col, int n, long attr)
{
	struct rasops_info *ri = cookie;
	struct ffb_softc *sc = ri->ri_hw;

	if ((row < 0) || (row >= ri->ri_rows))
		return;
	if (col < 0) {
		n += col;
		col = 0;
	}
	if (col + n > ri->ri_cols)
		n = ri->ri_cols - col;
	if (n <= 0)
		return;
	n *= ri->ri_font->fontwidth;
	col *= ri->ri_font->fontwidth;
	row *= ri->ri_font->fontheight;

	ffb_ras_fill(sc);
	ffb_ras_setfg(sc, ri->ri_devcmap[(attr >> 16) & 0xf]);
	ffb_ras_fifo_wait(sc, 4);
	FBC_WRITE(sc, FFB_FBC_BY, ri->ri_yorigin + row);
	FBC_WRITE(sc, FFB_FBC_BX, ri->ri_xorigin + col);
	FBC_WRITE(sc, FFB_FBC_BH, ri->ri_font->fontheight);
	FBC_WRITE(sc, FFB_FBC_BW, n - 1);
	ffb_ras_wait(sc);
}

void
ffb_ras_fill(struct ffb_softc *sc)
{
	ffb_ras_fifo_wait(sc, 2);
	FBC_WRITE(sc, FFB_FBC_ROP, FBC_ROP_NEW);
	FBC_WRITE(sc, FFB_FBC_DRAWOP, FBC_DRAWOP_RECTANGLE);
	ffb_ras_wait(sc);
}

void
ffb_ras_copyrows(void *cookie, int src, int dst, int n)
{
	struct rasops_info *ri = cookie;
	struct ffb_softc *sc = ri->ri_hw;

	if (dst == src)
		return;
	if (src < 0) {
		n += src;
		src = 0;
	}
	if ((src + n) > ri->ri_rows)
		n = ri->ri_rows - src;
	if (dst < 0) {
		n += dst;
		dst = 0;
	}
	if ((dst + n) > ri->ri_rows)
		n = ri->ri_rows - dst;
	if (n <= 0)
		return;
	n *= ri->ri_font->fontheight;
	src *= ri->ri_font->fontheight;
	dst *= ri->ri_font->fontheight;

	ffb_ras_fifo_wait(sc, 8);
	FBC_WRITE(sc, FFB_FBC_ROP, FBC_ROP_OLD | (FBC_ROP_OLD << 8));
	FBC_WRITE(sc, FFB_FBC_DRAWOP, FBC_DRAWOP_VSCROLL);
	FBC_WRITE(sc, FFB_FBC_BY, ri->ri_yorigin + src);
	FBC_WRITE(sc, FFB_FBC_BX, ri->ri_xorigin);
	FBC_WRITE(sc, FFB_FBC_DY, ri->ri_yorigin + dst);
	FBC_WRITE(sc, FFB_FBC_DX, ri->ri_xorigin);
	FBC_WRITE(sc, FFB_FBC_BH, n);
	FBC_WRITE(sc, FFB_FBC_BW, ri->ri_emuwidth);
	ffb_ras_wait(sc);
}

void
ffb_ras_setfg(struct ffb_softc *sc, int32_t fg)
{
	ffb_ras_fifo_wait(sc, 1);
	if (fg == sc->sc_fg_cache)
		return;
	sc->sc_fg_cache = fg;
	FBC_WRITE(sc, FFB_FBC_FG, fg);
	ffb_ras_wait(sc);
}

/* frame buffer generic driver support functions */
static void
ffbfb_unblank(struct device *dev)
{
	/* u_int on = 1; */

	if (dev && dev->dv_xname)
		printf("%s: ffbfb_unblank\n", dev->dv_xname);
	else
		printf("ffbfb_unblank(%p)n", dev);
	/* ffb_blank((struct ffb_softc*)dev, WSDISPLAYIO_SVIDEO, &on); */
}

int
ffbfb_open(dev_t dev, int flags, int mode, struct proc *p)
{
	int unit = minor(dev);

	if (unit >= ffb_cd.cd_ndevs || ffb_cd.cd_devs[unit] == NULL)
		return ENXIO;

	return 0;
}

int
ffbfb_close(dev_t dev, int flags, int mode, struct proc *p)
{
	return 0;
}

int
ffbfb_ioctl(dev_t dev, u_long cmd, caddr_t data, int flags, struct proc *p)
{
	struct ffb_softc *sc = ffb_cd.cd_devs[minor(dev)];

	return ffb_ioctl(sc, cmd, data, flags, p);
}

paddr_t
ffbfb_mmap(dev_t dev, off_t off, int prot)
{
	struct ffb_softc *sc = ffb_cd.cd_devs[minor(dev)];
	int i, reg;
	off_t o;

	/*
	 * off is a magic cookie (see xfree86/drivers/sunffb/ffb.h),
	 * which we map to an index into the "reg" property, and use
	 * our copy of the firmware data as arguments for the real
	 * mapping.
	 */
	static struct { unsigned long voff; int reg; } map[] = {
		{ 0x00000000, FFB_REG_SFB8R },
		{ 0x00400000, FFB_REG_SFB8G },
		{ 0x00800000, FFB_REG_SFB8B },
		{ 0x00c00000, FFB_REG_SFB8X },
		{ 0x01000000, FFB_REG_SFB32 },
		{ 0x02000000, FFB_REG_SFB64  },
		{ 0x04000000, FFB_REG_FBC },
		{ 0x04004000, FFB_REG_DFB8R },
		{ 0x04404000, FFB_REG_DFB8G },
		{ 0x04804000, FFB_REG_DFB8B },
		{ 0x04c04000, FFB_REG_DFB8X },
		{ 0x05004000, FFB_REG_DFB24 },
		{ 0x06004000, FFB_REG_DFB32 },
		{ 0x07004000, FFB_REG_DFB422A },
		{ 0x0bc06000, FFB_REG_DAC },
		{ 0x0bc08000, FFB_REG_PROM },
	};

	/* special value "FFB_EXP_VOFF" - not backed by any "reg" entry */
	if (off == 0x0bc18000)
		return bus_space_mmap(sc->sc_bt, sc->sc_addrs[FFB_REG_PROM],
		    0x00200000, prot, BUS_SPACE_MAP_LINEAR);

#define NELEMS(arr) (sizeof(arr)/sizeof((arr)[0]))

	/* the map is ordered by voff */
	for (i = 0; i < NELEMS(map); i++) {
		if (map[i].voff > off)
			break;		/* beyound */
		reg = map[i].reg;
		if (map[i].voff + sc->sc_sizes[reg] < off)
			continue;	/* not there yet */
		if (off > map[i].voff + sc->sc_sizes[reg])
			break;		/* out of range */
		o = off - map[i].voff;
		return bus_space_mmap(sc->sc_bt, sc->sc_addrs[reg], o, prot,
		    BUS_SPACE_MAP_LINEAR);
	}

	return -1;
}