NetBSD/sys/arch/pmax/dev/mfb.c

798 lines
20 KiB
C

/* $NetBSD: mfb.c,v 1.51 2003/10/31 03:32:19 simonb Exp $ */
/*-
* Copyright (c) 1992, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Ralph Campbell and Rick Macklem.
*
* 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. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
*
* @(#)mfb.c 8.1 (Berkeley) 6/10/93
*/
/*
* Mach Operating System
* Copyright (c) 1991,1990,1989 Carnegie Mellon University
* All Rights Reserved.
*
* Permission to use, copy, modify and distribute this software and its
* documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie the
* rights to redistribute these changes.
*/
/*
* devGraphics.c --
*
* This file contains machine-dependent routines for the graphics device.
*
* Copyright (C) 1989 Digital Equipment Corporation.
* Permission to use, copy, modify, and distribute this software and
* its documentation for any purpose and without fee is hereby granted,
* provided that the above copyright notice appears in all copies.
* Digital Equipment Corporation makes no representations about the
* suitability of this software for any purpose. It is provided "as is"
* without express or implied warranty.
*
* from: Header: /sprite/src/kernel/dev/ds3100.md/RCS/devGraphics.c,
* v 9.2 90/02/13 22:16:24 shirriff Exp SPRITE (DECWRL)";
*/
#include <sys/cdefs.h> /* RCS ID & Copyright macro defns */
__KERNEL_RCSID(0, "$NetBSD: mfb.c,v 1.51 2003/10/31 03:32:19 simonb Exp $");
#include <sys/param.h>
#include <sys/device.h>
#include <sys/systm.h>
#include <dev/tc/tcvar.h>
#include <machine/autoconf.h>
#include <machine/pmioctl.h>
#include <dev/sun/fbio.h>
#include <machine/fbvar.h>
#include <pmax/dev/mfbreg.h>
#include <pmax/dev/mfbvar.h>
#include <pmax/dev/fbreg.h>
/*
* These need to be mapped into user space.
*/
static struct fbuaccess mfbu;
static struct pmax_fbtty mfbfb;
static struct fbinfo *mfb_fi;
static void mfbPosCursor __P((struct fbinfo *fi, int x, int y));
#if 1 /* these go away when we use the abstracted-out chip drivers */
static void mfbLoadCursor __P((struct fbinfo *fi, u_short *ptr));
static void mfbRestoreCursorColor __P((struct fbinfo *fi));
static void mfbCursorColor __P((struct fbinfo *fi, u_int *color));
static void mfbInitColorMapBlack __P((struct fbinfo *fi, int blackpix));
static void mfbInitColorMap __P((struct fbinfo *fi));
static int mfbLoadColorMap __P((struct fbinfo *fi, u_char *mapbits,
int index, int count));
static int mfbLoadColorMapNoop __P((struct fbinfo *fi,
const u_char *mapbits, int index, int count));
#endif /* 1 */
/* new-style raster-cons "driver" methods */
static int mfbGetColorMap __P((struct fbinfo *fi, u_char *, int, int));
static int bt455_video_on __P((struct fbinfo *));
static int bt455_video_off __P((struct fbinfo *));
static void bt431_init __P((bt431_regmap_t *regs));
static void bt431_select_reg __P((bt431_regmap_t *regs, int regno));
static void bt431_write_reg __P((bt431_regmap_t *regs, int regno, int val));
#ifdef notused
static u_char bt431_read_reg __P((bt431_regmap_t *regs, int regno));
#endif
static void bt431_cursor_off __P((struct fbinfo *fi));
static void bt431_cursor_on __P((struct fbinfo *fi));
/*
* The default cursor.
*/
static u_short defCursor[32] = {
/* plane A */ 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF,
0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF,
/* plane B */ 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF,
0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF, 0x00FF
};
/*
* "driver" (member functions) for the raster-console (rcons) pseudo-device.
*/
struct fbdriver mfb_driver = {
bt455_video_on,
bt455_video_off,
mfbInitColorMap,
mfbGetColorMap,
mfbLoadColorMapNoop, /*LoadColorMap,*/
mfbPosCursor,
mfbLoadCursor,
mfbCursorColor
};
/*
* Register offsets
*/
#define MFB_OFFSET_VRAM 0x200000 /* from module's base */
#define MFB_OFFSET_BT431 0x180000 /* Bt431 registers */
#define MFB_OFFSET_BT455 0x100000 /* Bt455 registers */
#define MFB_OFFSET_IREQ 0x080000 /* Interrupt req. control */
#define MFB_OFFSET_ROM 0x0 /* Diagnostic ROM */
#define MFB_FB_SIZE 0x200000 /* frame buffer size */
/*
* driver frontend declaration for autoconfiguration.
*/
static int mfbmatch __P((struct device *, struct cfdata *, void *));
static void mfbattach __P((struct device *, struct device *, void *));
static int mfbinit __P((struct fbinfo *, caddr_t, int, int));
static int mfb_intr __P((void *sc));
CFATTACH_DECL(mfb, sizeof(struct fbinfo),
mfbmatch, mfbattach, NULL, NULL);
int
mfb_cnattach(addr)
paddr_t addr;
{
struct fbinfo *fi;
caddr_t base;
base = (caddr_t)MIPS_PHYS_TO_KSEG1(addr);
fbcnalloc(&fi);
if (mfbinit(fi, base, 0, 1) < 0)
return (0);
mfb_fi = fi;
return (1);
}
static int
mfbmatch(parent, match, aux)
struct device *parent;
struct cfdata *match;
void *aux;
{
struct tc_attach_args *ta = aux;
/* make sure that we're looking for this type of device. */
if (!TC_BUS_MATCHNAME(ta, "PMAG-AA "))
return (0);
return (1);
}
static void
mfbattach(parent, self, aux)
struct device *parent;
struct device *self;
void *aux;
{
struct tc_attach_args *ta = aux;
caddr_t mfbaddr = (caddr_t)ta->ta_addr;
int unit = self->dv_unit;
struct fbinfo *fi;
if (mfb_fi)
fi = mfb_fi;
else {
if (fballoc(&fi) < 0 || mfbinit(fi, mfbaddr, unit, 0) < 0)
return /* failed */;
}
((struct fbsoftc *)self)->sc_fi = fi;
printf(": %dx%dx%d%s",
fi->fi_type.fb_width,
fi->fi_type.fb_height,
fi->fi_type.fb_depth,
(mfb_fi) ? " console" : "");
/*
* 3MIN does not mask un-established TC option interrupts,
* so establish a handler.
* XXX Should store cmap updates in softc and apply in the
* interrupt handler, which interrupts during vertical-retrace.
*/
tc_intr_establish(parent, ta->ta_cookie, TC_IPL_NONE, mfb_intr, fi);
printf("\n");
}
/*
* Initialization
*/
int
mfbinit(fi, mfbaddr, unit, silent)
struct fbinfo *fi;
caddr_t mfbaddr;
int unit;
int silent;
{
int isconsole = 0;
/* check for no frame buffer */
if (badaddr(mfbaddr, 4)) {
printf("mfb: bad address 0x%p\n", mfbaddr);
return (0);
}
/* Fill in main frame buffer info struct. */
fi->fi_unit = unit;
fi->fi_pixels = (caddr_t)(mfbaddr + MFB_OFFSET_VRAM);
fi->fi_pixelsize = 2048 * 1024;
fi->fi_base = (caddr_t)(mfbaddr + MFB_OFFSET_BT431);
fi->fi_vdac = (caddr_t)(mfbaddr + MFB_OFFSET_BT455);
fi->fi_size = (fi->fi_pixels + MFB_FB_SIZE) - fi->fi_base;
fi->fi_linebytes = 2048; /* inter-line stride (blitting) */
fi->fi_driver = &mfb_driver;
fi->fi_blanked = 0;
/* Fill in Frame Buffer Type struct. */
fi->fi_type.fb_type = PMAX_FBTYPE_MFB;
fi->fi_type.fb_width = 1280; /* visible screen pixels */
fi->fi_type.fb_height = 1024;
fi->fi_type.fb_depth = 8;
fi->fi_type.fb_cmsize = 0;
fi->fi_type.fb_size = MFB_FB_SIZE;
/*
* Reset the video chip.
*/
bt431_init ((bt431_regmap_t *) fi->fi_base);
mfbLoadCursor(fi, defCursor); /*XXX*/ /* Is this necessary? */
/*
* qvss/pm-style mmap()ed event queue compatibility glue
*/
/*
* Must be in Uncached space since the fbuaccess structure is
* mapped into the user's address space uncached.
*/
fi->fi_fbu = (struct fbuaccess *)
MIPS_PHYS_TO_KSEG1(MIPS_KSEG0_TO_PHYS(&mfbu));
/* This is glass-tty state but it's in the shared structure. Ick. */
fi->fi_fbu->scrInfo.max_row = 67;
fi->fi_fbu->scrInfo.max_col = 80;
init_pmaxfbu(fi);
/*
* Initialize old-style pmax glass-tty screen info.
*/
fi->fi_glasstty = &mfbfb;
/*
* Initialize the color map, the screen, and the mouse.
*/
if (tb_kbdmouseconfig(fi))
return (-1);
/*
* black-on-white during first initialization of console,
* white-on-black otherwise.
*/
mfbInitColorMapBlack(fi, isconsole);
/*
* Connect to the raster-console pseudo-driver.
*/
fbconnect(fi);
return (0);
}
static u_char cursor_RGB[6]; /* cursor color 2 & 3 */
static void
bt431_cursor_on(fi)
struct fbinfo *fi;
{
mfbRestoreCursorColor(fi);
}
static void
bt431_cursor_off(fi)
struct fbinfo *fi;
{
u_char cursor_save [6];
/* Stash the current cursor color (and overlay). */
memcpy(cursor_save, cursor_RGB, sizeof(cursor_RGB));
/* Zero the cursor colors. */
memset(cursor_RGB, 0, sizeof(cursor_RGB));
/* Write the zeroed colors to the hardware and fb color map. */
mfbRestoreCursorColor (fi);
/*
* Replace stashed colors, so the cursor will be visible next
* time the cursor color map is restored.
*/
memcpy(cursor_RGB, cursor_save, sizeof(cursor_RGB));
}
/*
* There are actually 2 Bt431 cursor sprite chips that each generate 1 bit
* of each cursor pixel for a 2bit 64x64 cursor sprite. The corresponding
* registers for these two chips live in adjacent bytes of the shorts that
* are defined in bt431_regmap_t.
*/
static void
mfbLoadCursor(fi, cursor)
struct fbinfo *fi;
u_short *cursor;
{
int i, j, k, pos;
u_short ap, bp, out;
bt431_regmap_t *regs;
regs = (bt431_regmap_t *)(fi -> fi_base);
/*
* Fill in the cursor sprite using the A and B planes, as provided
* for the pmax.
* XXX This will have to change when the X server knows that this
* is not a pmax display. (ie. Not the Xcfbpmax server.)
*/
pos = 0;
bt431_select_reg(regs, BT431_REG_CRAM_BASE);
for (k = 0; k < 16; k++) {
ap = *cursor;
bp = *(cursor + 16);
j = 0;
while (j < 2) {
out = 0;
for (i = 0; i < 8; i++) {
out = (out << 1) | ((bp & 0x1) << 8) |
(ap & 0x1);
ap >>= 1;
bp >>= 1;
}
BT431_WRITE_CMAP_AUTOI(regs, out);
pos++;
j++;
}
while (j < 8) {
BT431_WRITE_CMAP_AUTOI(regs, 0);
pos++;
j++;
}
cursor++;
}
while (pos < 512) {
BT431_WRITE_CMAP_AUTOI(regs, 0);
pos++;
}
/* Turn on the cmap entries used for the cursor. */
bt431_cursor_on(fi);
}
/* Restore the color of the cursor. */
static void
mfbRestoreCursorColor (fi)
struct fbinfo *fi;
{
bt455_regmap_t *regs = (bt455_regmap_t *)(fi -> fi_vdac);
u_char cm [3];
u_char fg;
if (cursor_RGB[0] || cursor_RGB[1] || cursor_RGB[2])
cm [0] = cm [1] = cm [2] = 0xff;
else
cm [0] = cm [1] = cm [2] = 0;
mfbLoadColorMap(fi, cm, 8, 1);
mfbLoadColorMap(fi, cm, 9, 1);
if (cursor_RGB[3] || cursor_RGB[4] || cursor_RGB[5])
fg = 0xf;
else
fg = 0;
regs->addr_ovly = fg;
tc_wmb();
regs->addr_ovly = fg;
tc_wmb();
regs->addr_ovly = fg;
tc_wmb();
}
/* Set the color of the cursor. */
static void
mfbCursorColor(fi, color)
struct fbinfo *fi;
unsigned int color[];
{
int i;
for (i = 0; i < 6; i++)
cursor_RGB[i] = (u_char)(color[i] >> 8);
mfbRestoreCursorColor (fi);
}
/* Position the cursor. */
static void
mfbPosCursor(fi, x, y)
struct fbinfo *fi;
int x, y;
{
bt431_regmap_t *regs = (bt431_regmap_t *)(fi -> fi_base);
#ifdef MELLON
if (y < 0)
y = 0;
else if (y > fi -> fi_type.fb_height - fi -> fi_cursor.height - 1)
y = fi -> fi_type.fb_height - fi -> fi_cursor.height - 1;
if (x < 0)
x = 0;
else if (x > fi -> fi_type.fb_width - fi -> fi_cursor.width - 1)
x = fi -> fi_type.fb_width - fi -> fi_cursor.width - 1;
#else /* old-style pmax glass tty */
if (y < fi->fi_fbu->scrInfo.min_cur_y ||
y > fi->fi_fbu->scrInfo.max_cur_y)
y = fi->fi_fbu->scrInfo.max_cur_y;
if (x < fi->fi_fbu->scrInfo.min_cur_x ||
x > fi->fi_fbu->scrInfo.max_cur_x)
x = fi->fi_fbu->scrInfo.max_cur_x;
#endif /* old-style pmax glass tty */
fi -> fi_cursor.x = x;
fi -> fi_cursor.y = y;
#define lo(v) ((v)&0xff)
#define hi(v) (((v)&0xf00)>>8)
/*
* Cx = x + D + H - P
* P = 37 if 1:1, 52 if 4:1, 57 if 5:1
* D = pixel skew between outdata and external data
* H = pixels between HSYNCH falling and active video
*
* Cy = y + V - 32
* V = scanlines between HSYNCH falling, two or more
* clocks after VSYNCH falling, and active video
*/
bt431_write_reg(regs, BT431_REG_CXLO, lo(x + 360));
BT431_WRITE_REG_AUTOI(regs, hi(x + 360));
BT431_WRITE_REG_AUTOI(regs, lo(y + 36));
BT431_WRITE_REG_AUTOI(regs, hi(y + 36));
}
/*
* Initialize the colormap to the default state.
* For the text console, entry zero is black and all other entries are
* full white.
* During the first console initialization, and when the framebuffer
* device is open, entry zero is full white and all other entries are
* black.
* The hardware cursor is turned off.
*/
static void
mfbInitColorMapBlack(fi, blackpix)
struct fbinfo *fi;
int blackpix;
{
u_char rgb [3];
int i;
if (blackpix)
rgb [0] = rgb [1] = rgb [2] = 0xff;
else
rgb [0] = rgb [1] = rgb [2] = 0;
mfbLoadColorMap(fi, rgb, 0, 1);
if (blackpix)
rgb [0] = rgb [1] = rgb [2] = 0;
else
rgb [0] = rgb [1] = rgb [2] = 0xff;
for (i = 1; i < 16; i++) {
mfbLoadColorMap(fi, rgb, i, 1);
}
/* initialize cmap entries for cursor sprite value and mask */
for (i = 0; i < 3; i++) {
cursor_RGB[i] = 0;
cursor_RGB[i + 3] = 0xff;
}
bt431_cursor_off(fi);
}
/* set colormap for open/close */
static void
mfbInitColorMap(fi)
struct fbinfo *fi;
{
mfbInitColorMapBlack(fi, fi->fi_open);
}
/* Load the color map. */
static int
mfbLoadColorMap(fi, bits, index, count)
struct fbinfo *fi;
u_char *bits;
int index, count;
{
bt455_regmap_t *regs = (bt455_regmap_t *)(fi -> fi_vdac);
u_char *cmap_bits;
u_char *cmap;
int i;
if (count < 0 || index < 0 || index + count > 15)
return EINVAL;
/* We will read COUNT red, green, and blue values from cmap_bits */
cmap_bits = (u_char *)bits;
/*
* We will save these rgb values in our local palette, starting
* at the correct offset for color map entry to be changed,
* which is specified in INDEX.
*/
cmap = (u_char *)(fi -> fi_cmap_bits) + index * 3;
/* Select the correct starting hardware register for entry INDEX. */
BT455_SELECT_ENTRY(regs, index);
/*
* We iterate through this loop three times for each changed
* color map entry (once for red, once for green, once for blue.)
* On each pass we stash away the user-specified intensity in
* CMAP (which is already based at the correct offset for the
* first color map entry to be changed!) Then *after* saving
* the value we shift right by 4 bits and write it to the
* (auto-incremented) hardware register. The right-shift has the
* effect of making "low" intensities be zero values, and "high"
* intensities non-zero values, which is the best we can do on
* the black-and-white mfb.
* If the framebuffer is blanked, no changes are written to the
* hardware at this time.
*/
for (i = 0; i < (count * 3); i++) {
cmap[i] = cmap_bits[i];
if (! fi->fi_blanked) {
regs->addr_cmap_data = cmap [i] >> 4;
tc_wmb();
}
}
return 0;
}
/* stub for driver */
static int
mfbLoadColorMapNoop(fi, bits, index, count)
struct fbinfo *fi;
const u_char *bits;
int index, count;
{
return 0;
}
/* Get the color map. */
static int
mfbGetColorMap(fi, bits, index, count)
struct fbinfo *fi;
u_char *bits;
int index, count;
{
/*bt455_regmap_t *regs = (bt455_regmap_t *)(fi -> fi_vdac);*/
u_char *cmap_bits;
u_char *cmap;
if (index > 15 || index < 0 || index + count > 15)
return EINVAL;
cmap_bits = (u_char *)bits;
cmap = (u_char *)(fi -> fi_cmap_bits) + index * 3;
memcpy(cmap_bits, cmap, count * 3);
return 0;
}
/* Enable the video display. */
static int
bt455_video_on(fi)
struct fbinfo *fi;
{
int i;
bt455_regmap_t *regs = (bt455_regmap_t *)(fi -> fi_vdac);
u_char *cmap;
if (!fi -> fi_blanked)
return 0;
fi -> fi_blanked = 0;
cmap = (u_char *)(fi -> fi_cmap_bits);
/* restore old color map entries 0 and 1 */
BT455_SELECT_ENTRY(regs, 0);
for (i = 0; i < 6; i++) {
regs->addr_cmap_data = cmap [i] >> 4;
tc_wmb();
}
mfbRestoreCursorColor (fi);
return 0;
}
/*
* ----------------------------------------------------------------------------
*
* bt455_video_off
*
* Disable the video display.
*
* Results:
* None.
*
* Side effects:
* The display is disabled.
*
* ----------------------------------------------------------------------------
*/
static int
bt455_video_off(fi)
struct fbinfo *fi;
{
int i;
bt455_regmap_t *regs = (bt455_regmap_t *)(fi -> fi_vdac);
if (fi -> fi_blanked)
return 0;
/* Zap colormap entries 0 (background) and 1 (foreground) */
BT455_SELECT_ENTRY(regs, 0);
for (i = 0; i < 6; i++) {
regs->addr_cmap_data = 0;
tc_wmb();
}
/* and the cursor.. */
bt431_cursor_off(fi);
fi -> fi_blanked = 1;
return 0;
}
/*
* Generic register access
*/
static void
bt431_select_reg(regs, regno)
bt431_regmap_t *regs;
{
regs->addr_lo = SET_VALUE(regno & 0xff);
regs->addr_hi = SET_VALUE((regno >> 8) & 0xff);
tc_wmb();
}
static void
bt431_write_reg(regs, regno, val)
bt431_regmap_t *regs;
{
bt431_select_reg(regs, regno);
regs->addr_reg = SET_VALUE(val);
tc_wmb();
}
#ifdef notused
static u_char
bt431_read_reg(regs, regno)
bt431_regmap_t *regs;
{
bt431_select_reg(regs, regno);
return (GET_VALUE(regs->addr_reg));
}
#endif
static void
bt431_init(regs)
bt431_regmap_t *regs;
{
/* use 4:1 input mux */
bt431_write_reg(regs, BT431_REG_CMD,
BT431_CMD_CURS_ENABLE|BT431_CMD_OR_CURSORS|
BT431_CMD_4_1_MUX|BT431_CMD_THICK_1);
/* home cursor */
BT431_WRITE_REG_AUTOI(regs, 0x00);
BT431_WRITE_REG_AUTOI(regs, 0x00);
BT431_WRITE_REG_AUTOI(regs, 0x00);
BT431_WRITE_REG_AUTOI(regs, 0x00);
/* no crosshair window */
BT431_WRITE_REG_AUTOI(regs, 0x00);
BT431_WRITE_REG_AUTOI(regs, 0x00);
BT431_WRITE_REG_AUTOI(regs, 0x00);
BT431_WRITE_REG_AUTOI(regs, 0x00);
BT431_WRITE_REG_AUTOI(regs, 0x00);
BT431_WRITE_REG_AUTOI(regs, 0x00);
BT431_WRITE_REG_AUTOI(regs, 0x00);
BT431_WRITE_REG_AUTOI(regs, 0x00);
}
/*
* copied from cfb_intr
*/
static int
mfb_intr(sc)
void *sc;
{
struct fbinfo *fi;
volatile int junk;
char *slot_addr;
fi = (struct fbinfo *)sc;
slot_addr = (((char *)fi->fi_base) - MFB_OFFSET_BT431);
/* reset vertical-retrace interrupt by writing a dont-care */
junk = *(volatile int*) (slot_addr + MFB_OFFSET_IREQ);
*(volatile int*) (slot_addr + MFB_OFFSET_IREQ) = 0;
return (0);
}