path: root/sys/arch/sparc/dev/cgfourteen.c

/*	$OpenBSD: cgfourteen.c,v 1.36 2008/12/26 22:30:21 miod Exp $	*/
/*	$NetBSD: cgfourteen.c,v 1.7 1997/05/24 20:16:08 pk Exp $ */

/*
 * Copyright (c) 2002, 2003, 2005 Miodrag Vallat.
 *
 * 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.
 *
 * 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.
 *
 *
 * Copyright (c) 1996
 *	The President and Fellows of Harvard College. All rights reserved.
 * Copyright (c) 1992, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This software was developed by the Computer Systems Engineering group
 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
 * contributed to Berkeley.
 *
 * All advertising materials mentioning features or use of this software
 * must display the following acknowledgement:
 *	This product includes software developed by Harvard University.
 *	This product includes software developed by the University of
 *	California, Lawrence Berkeley Laboratory.
 *
 * 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 the University of
 *	California, Berkeley and its contributors.
 *	This product includes software developed by Harvard University and
 *	its contributors.
 * 4. 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.
 *
 *   Based on:
 *	NetBSD: cgthree.c,v 1.28 1996/05/31 09:59:22 pk Exp
 *	NetBSD: cgsix.c,v 1.25 1996/04/01 17:30:00 christos Exp
 */

/*
 * Driver for Campus-II on-board mbus-based video (cgfourteen).
 *
 * XXX should bring hardware cursor code back
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/buf.h>
#include <sys/device.h>
#include <sys/ioctl.h>
#include <sys/malloc.h>
#include <sys/mman.h>
#include <sys/tty.h>
#include <sys/conf.h>

#include <uvm/uvm_extern.h>

#include <machine/autoconf.h>
#include <machine/pmap.h>
#include <machine/cpu.h>
#include <machine/conf.h>

#include <dev/wscons/wsconsio.h>
#include <dev/wscons/wsdisplayvar.h>
#include <dev/rasops/rasops.h>
#include <machine/fbvar.h>

#include <sparc/dev/cgfourteenreg.h>

#include <dev/cons.h>	/* for prom console hook */

/*
 * Per-display variables/state
 */

union cgfourteen_cmap {
	u_char  	cm_map[256][4];	/* 256 R/G/B/A entries (B is high)*/
	u_int32_t   	cm_chip[256];	/* the way the chip gets loaded */
};

struct cgfourteen_softc {
	struct	sunfb sc_sunfb;		/* common base part */

	struct 	rom_reg	sc_phys;	/* phys address of frame buffer */
	union	cgfourteen_cmap sc_cmap; /* current colormap */
	u_int	sc_cmap_start, sc_cmap_count;	/* deferred cmap range */

	/* registers mappings */
	struct	cg14ctl  *sc_ctl;
	struct	cg14curs *sc_hwc;
	struct 	cg14dac	 *sc_dac;
	struct	cg14xlut *sc_xlut;
	struct 	cg14clut *sc_clut1;
	struct	cg14clut *sc_clut2;
	struct	cg14clut *sc_clut3;
	u_int32_t *sc_autoincr;

	int	sc_rev;			/* VSIMM revision */
	int	sc_32;			/* can do 32bit at this resolution */
	size_t	sc_vramsize;		/* total video memory size */

	struct	intrhand sc_ih;
};

int	cgfourteen_ioctl(void *, u_long, caddr_t, int, struct proc *);
paddr_t	cgfourteen_mmap(void *, off_t, int);
void	cgfourteen_reset(struct cgfourteen_softc *, int);
void	cgfourteen_burner(void *, u_int, u_int);

int	cgfourteen_getcmap(union cgfourteen_cmap *, struct wsdisplay_cmap *);
int	cgfourteen_intr(void *);
void	cgfourteen_loadcmap_deferred(struct cgfourteen_softc *, u_int, u_int);
void	cgfourteen_loadcmap_immediate(struct cgfourteen_softc *, u_int, u_int);
void	cgfourteen_prom(void *);
int	cgfourteen_putcmap(union cgfourteen_cmap *, struct wsdisplay_cmap *);
void	cgfourteen_setcolor(void *, u_int, u_int8_t, u_int8_t, u_int8_t);

struct wsdisplay_accessops cgfourteen_accessops = {
	cgfourteen_ioctl,
	cgfourteen_mmap,
	NULL,	/* alloc_screen */
	NULL,	/* free_screen */
	NULL,	/* show_screen */
	NULL,	/* load_font */
	NULL,	/* scrollback */
	NULL,	/* getchar */
	cgfourteen_burner,
	NULL	/* pollc */
};

void	cgfourteenattach(struct device *, struct device *, void *);
int	cgfourteenmatch(struct device *, void *, void *);

struct cfattach cgfourteen_ca = {
	sizeof(struct cgfourteen_softc), cgfourteenmatch, cgfourteenattach
};

struct cfdriver cgfourteen_cd = {
	NULL, "cgfourteen", DV_DULL
};

/*
 * Match a cgfourteen.
 */
int
cgfourteenmatch(struct device *parent, void *vcf, void *aux)
{
	struct cfdata *cf = vcf;
	struct confargs *ca = aux;
	struct romaux *ra = &ca->ca_ra;

	if (strcmp(cf->cf_driver->cd_name, ra->ra_name))
		return (0);

	/*
	 * This driver should not be attached without an "addr" locator,
	 * as this is the only way to differentiate the main and secondary
	 * VSIMM.
	 */
	if (cf->cf_loc[0] != -1 && cf->cf_loc[0] != (int)ra->ra_paddr)
		return (0);

	/*
	 * The cgfourteen is a local-bus video adaptor, accessed directly
	 * via the processor, and not through device space or an external
	 * bus. Thus we look _only_ at the obio bus.
	 * Additionally, these things exist only on the Sun4m.
	 */
	if (CPU_ISSUN4M && ca->ca_bustype == BUS_OBIO)
		return (1);

	return (0);
}

/*
 * Attach a display.
 */
void
cgfourteenattach(struct device *parent, struct device *self, void *args)
{
	struct cgfourteen_softc *sc = (struct cgfourteen_softc *)self;
	struct confargs *ca = args;
	int node, pri, i;
	u_int32_t *lut;
	int isconsole;
	char *nam;

	pri = ca->ca_ra.ra_intr[0].int_pri;
	printf(" pri %d: ", pri);

	/*
	 * Sanity checks
	 */
	if (ca->ca_ra.ra_len < 0x10000) {
		printf("expected %x bytes of control registers, got %x\n",
		    0x10000, ca->ca_ra.ra_len);
		return;
	}
	if (ca->ca_ra.ra_nreg < CG14_NREG) {
		printf("expected %d registers, got %d\n",
		    CG14_NREG, ca->ca_ra.ra_nreg);
		return;
	}
	if (ca->ca_ra.ra_nintr != 1) {
		printf("expected 1 interrupt, got %d\n", ca->ca_ra.ra_nintr);
		return;
	}

	node = ca->ca_ra.ra_node;
	nam = getpropstring(node, "model");
	if (*nam != '\0')
		printf("%s, ", nam);

	isconsole = node == fbnode;

	/*
	 * Map in the 8 useful pages of registers
	 */
	sc->sc_ctl = (struct cg14ctl *) mapiodev(
	    &ca->ca_ra.ra_reg[CG14_REG_CONTROL], 0, ca->ca_ra.ra_len);

	sc->sc_hwc = (struct cg14curs *) ((u_int)sc->sc_ctl +
					  CG14_OFFSET_CURS);
	sc->sc_dac = (struct cg14dac *) ((u_int)sc->sc_ctl +
					 CG14_OFFSET_DAC);
	sc->sc_xlut = (struct cg14xlut *) ((u_int)sc->sc_ctl +
					   CG14_OFFSET_XLUT);
	sc->sc_clut1 = (struct cg14clut *) ((u_int)sc->sc_ctl +
					    CG14_OFFSET_CLUT1);
	sc->sc_clut2 = (struct cg14clut *) ((u_int)sc->sc_ctl +
					    CG14_OFFSET_CLUT2);
	sc->sc_clut3 = (struct cg14clut *) ((u_int)sc->sc_ctl +
					    CG14_OFFSET_CLUT3);
	sc->sc_autoincr = (u_int32_t *) ((u_int)sc->sc_ctl +
				     CG14_OFFSET_AUTOINCR);

	sc->sc_rev =
	    (sc->sc_ctl->ctl_rsr & CG14_RSR_REVMASK) >> CG14_RSR_REVSHIFT;

	printf("%dMB, rev %d.%d", ca->ca_ra.ra_reg[CG14_REG_VRAM].rr_len >> 20,
	    sc->sc_rev, sc->sc_ctl->ctl_rsr & CG14_RSR_IMPLMASK);

	sc->sc_phys = ca->ca_ra.ra_reg[CG14_REG_VRAM];

	fb_setsize(&sc->sc_sunfb, 8, 1152, 900, node, ca->ca_bustype);

	/*
	 * The prom will report depth == 8, since this is the mode it will
	 * get initialized in.
	 * Check if we will be able to use 32 bit mode later (i.e. if it will
	 * fit in the video memory. Note that, if this is not the case, the
	 * VSIMM will usually not appear in the OBP device tree!
	 */
	sc->sc_vramsize = ca->ca_ra.ra_reg[CG14_REG_VRAM].rr_len;
	sc->sc_32 = sc->sc_sunfb.sf_fbsize * 4 <= sc->sc_vramsize;

	sc->sc_sunfb.sf_ro.ri_bits = mapiodev(&ca->ca_ra.ra_reg[CG14_REG_VRAM],
	    0,	/* CHUNKY_XBGR */
	    sc->sc_vramsize);

	printf(", %dx%d\n", sc->sc_sunfb.sf_width, sc->sc_sunfb.sf_height);

	sc->sc_ih.ih_fun = cgfourteen_intr;
	sc->sc_ih.ih_arg = sc;
	intr_establish(pri, &sc->sc_ih, IPL_FB, self->dv_xname);

	/*
	 * Reset frame buffer controls
	 */
	sc->sc_sunfb.sf_depth = 0;	/* force action */
	cgfourteen_reset(sc, 8);

	/*
	 * Grab the initial colormap
	 */
	lut = (u_int32_t *)sc->sc_clut1->clut_lut;
	for (i = 0; i < CG14_CLUT_SIZE; i++)
		sc->sc_cmap.cm_chip[i] = lut[i];

	/*
	 * Enable the video.
	 */
	cgfourteen_burner(sc, 1, 0);

	sc->sc_sunfb.sf_ro.ri_hw = sc;
	fbwscons_init(&sc->sc_sunfb, isconsole);
	fbwscons_setcolormap(&sc->sc_sunfb, cgfourteen_setcolor);

	if (isconsole) {
		fbwscons_console_init(&sc->sc_sunfb, -1);
		shutdownhook_establish(cgfourteen_prom, sc);
	}

	fbwscons_attach(&sc->sc_sunfb, &cgfourteen_accessops, isconsole);
}

int
cgfourteen_ioctl(void *dev, u_long cmd, caddr_t data, int flags, struct proc *p)
{
	struct cgfourteen_softc *sc = dev;
	struct wsdisplay_cmap *cm;
	struct wsdisplay_fbinfo *wdf;
	int error;

	/*
	 * Note that, although the emulation (text) mode is running in a
	 * 8-bit plane, we advertize the frame buffer as 32-bit if it can
	 * support this mode.
	 */
	switch (cmd) {
	case WSDISPLAYIO_GTYPE:
		*(u_int *)data = WSDISPLAY_TYPE_SUNCG14;
		break;
	case WSDISPLAYIO_GINFO:
		wdf = (struct wsdisplay_fbinfo *)data;
		wdf->height = sc->sc_sunfb.sf_height;
		wdf->width = sc->sc_sunfb.sf_width;
		wdf->depth = sc->sc_32 ? 32 : 8;
		wdf->cmsize = sc->sc_32 ? 0 : 256;
		break;
	case WSDISPLAYIO_GETSUPPORTEDDEPTH:
		if (sc->sc_32)
			*(u_int *)data = WSDISPLAYIO_DEPTH_24_32;
		else
			return (-1);
		break;
	case WSDISPLAYIO_LINEBYTES:
		if (sc->sc_32)
			*(u_int *)data = sc->sc_sunfb.sf_linebytes * 4;
		else
			*(u_int *)data = sc->sc_sunfb.sf_linebytes;
		break;

	case WSDISPLAYIO_GETCMAP:
		if (sc->sc_32 == 0) {
			cm = (struct wsdisplay_cmap *)data;
			error = cgfourteen_getcmap(&sc->sc_cmap, cm);
			if (error)
				return (error);
		}
		break;
	case WSDISPLAYIO_PUTCMAP:
		if (sc->sc_32 == 0) {
			cm = (struct wsdisplay_cmap *)data;
			error = cgfourteen_putcmap(&sc->sc_cmap, cm);
			if (error)
				return (error);
			cgfourteen_loadcmap_deferred(sc, cm->index, cm->count);
		}
		break;

	case WSDISPLAYIO_SMODE:
		if (*(int *)data == WSDISPLAYIO_MODE_EMUL) {
			/* Back from X11 to text mode */
			cgfourteen_reset(sc, 8);
		} else {
			/* Starting X11, try to switch to 32 bit mode */
			if (sc->sc_32)
				cgfourteen_reset(sc, 32);
		}
		break;

	case WSDISPLAYIO_GVIDEO:
	case WSDISPLAYIO_SVIDEO:
		break;

	default:
		return (-1);	/* not supported yet */
	}
	return (0);
}

/*
 * Return the address that would map the given device at the given
 * offset, allowing for the given protection, or return -1 for error.
 */
paddr_t
cgfourteen_mmap(void *v, off_t offset, int prot)
{
	struct cgfourteen_softc *sc = v;
	
	if (offset & PGOFSET || offset < 0)
		return (-1);

	/* Allow mapping as a dumb framebuffer from offset 0 */
	if (offset < sc->sc_sunfb.sf_fbsize * (sc->sc_32 ? 4 : 1)) {
		return (REG2PHYS(&sc->sc_phys, offset) | PMAP_NC);
	}

	return (-1);
}

/* Initialize the framebuffer, storing away useful state for later reset */
void
cgfourteen_reset(struct cgfourteen_softc *sc, int depth)
{
	u_int i;

	if (sc->sc_sunfb.sf_depth != depth) {
		if (depth == 8) {
			/*
			 * Enable the video and put it in 8 bit mode
			 */
			if (sc->sc_rev == 0)
				sc->sc_ctl->ctl_mctl = CG14_MCTL_R0_ENABLEHW |
				    CG14_MCTL_PIXMODE_8;
			else
				sc->sc_ctl->ctl_mctl = CG14_MCTL_R1_ENABLEHW |
				    CG14_MCTL_R1_ENABLEVID |
				    CG14_MCTL_PIXMODE_8;

			fbwscons_setcolormap(&sc->sc_sunfb,
			    cgfourteen_setcolor);
		} else {
			/*
			 * Clear the screen to black
			 */
			bzero(sc->sc_sunfb.sf_ro.ri_bits,
			    sc->sc_sunfb.sf_fbsize);

			/*
			 * Enable the video, and put in 32 bit mode
			 */
			if (sc->sc_rev == 0)
				sc->sc_ctl->ctl_mctl = CG14_MCTL_R0_ENABLEHW |
				    CG14_MCTL_PIXMODE_32;
			else
				sc->sc_ctl->ctl_mctl = CG14_MCTL_R1_ENABLEHW |
				    CG14_MCTL_R1_ENABLEVID |
				    CG14_MCTL_PIXMODE_32;

			/*
			 * Zero the xlut to enable direct-color mode
			 */
			sc->sc_xlut->xlut_lutinc[0] = 0;
			for (i = CG14_CLUT_SIZE; i; i--)
				*sc->sc_autoincr = 0;
		}
	}

	sc->sc_cmap_count = 0;
	sc->sc_sunfb.sf_depth = depth;
}

void
cgfourteen_prom(void *v)
{
	struct cgfourteen_softc *sc = v;
	extern struct consdev consdev_prom;

	if (sc->sc_sunfb.sf_depth != 8) {
		/*
		 * Go back to 8-bit mode.
		 */
		cgfourteen_reset(sc, 8);

		/*
		 * Go back to prom output for the last few messages, so they
		 * will be displayed correctly.
		 */
		cn_tab = &consdev_prom;
	}
}

void
cgfourteen_burner(void *v, u_int on, u_int flags)
{
	struct cgfourteen_softc *sc = v;
	u_int bits;

	/*
	 * We can only use DPMS to power down the display if the chip revision
	 * is greater than 0.
	 */
	if (sc->sc_rev == 0)
		bits = CG14_MCTL_R0_ENABLEHW;
	else
		bits = CG14_MCTL_R1_ENABLEHW | CG14_MCTL_R1_ENABLEVID;

	if (on) {
		sc->sc_ctl->ctl_mctl |= bits;
	} else {
		sc->sc_ctl->ctl_mctl &= ~bits;
	}
}

/* Read the software shadow colormap */
int
cgfourteen_getcmap(union cgfourteen_cmap *cm, struct wsdisplay_cmap *rcm)
{
	u_int index = rcm->index, count = rcm->count, i;
	int error;

	if (index >= CG14_CLUT_SIZE || count > CG14_CLUT_SIZE - index)
                return (EINVAL);

	for (i = 0; i < count; i++) {
		if ((error = copyout(&cm->cm_map[index + i][3],
		    &rcm->red[i], 1)) != 0)
			return (error);
		if ((error = copyout(&cm->cm_map[index + i][2],
		    &rcm->green[i], 1)) != 0)
			return (error);
		if ((error = copyout(&cm->cm_map[index + i][1],
		    &rcm->blue[i], 1)) != 0)
			return (error);
	}
	return (0);
}

/* Write the software shadow colormap */
int
cgfourteen_putcmap(union cgfourteen_cmap *cm, struct wsdisplay_cmap *rcm)
{
	u_int index = rcm->index, count = rcm->count, i;
	int error;

	if (index >= CG14_CLUT_SIZE || count > CG14_CLUT_SIZE - index)
                return (EINVAL);

	for (i = 0; i < count; i++) {
		if ((error = copyin(&rcm->red[i],
		    &cm->cm_map[index + i][3], 1)) != 0)
			return (error);
		if ((error = copyin(&rcm->green[i],
		    &cm->cm_map[index + i][2], 1)) != 0)
			return (error);
		if ((error = copyin(&rcm->blue[i],
		    &cm->cm_map[index + i][1], 1)) != 0)
			return (error);
		cm->cm_map[index +i][0] = 0;	/* no alpha channel */
	}
	return (0);
}

void
cgfourteen_loadcmap_deferred(struct cgfourteen_softc *sc, u_int start,
    u_int ncolors)
{
	u_int end;

	/* Grow the deferred colormap update range if necessary */
	if (sc->sc_cmap_count == 0) {
		sc->sc_cmap_start = start;
		sc->sc_cmap_count = ncolors;
	} else {
		end = MAX(start + ncolors,
		    sc->sc_cmap_start + sc->sc_cmap_count);
		sc->sc_cmap_start = min(sc->sc_cmap_start, start);
		sc->sc_cmap_count = end - sc->sc_cmap_start;
	}

	/* Enable interrupts */
	sc->sc_ctl->ctl_mctl |= CG14_MCTL_ENABLEINTR;
}

void
cgfourteen_loadcmap_immediate(struct cgfourteen_softc *sc, u_int start,
    u_int ncolors)
{
	u_int32_t *colp = &sc->sc_cmap.cm_chip[start];

	sc->sc_clut1->clut_lutinc[start] = 0;
	while (ncolors-- != 0)
		*sc->sc_autoincr = *colp++;
}

void
cgfourteen_setcolor(void *v, u_int index, u_int8_t r, u_int8_t g, u_int8_t b)
{
	struct cgfourteen_softc *sc = v;

	sc->sc_cmap.cm_map[index][3] = r;
	sc->sc_cmap.cm_map[index][2] = g;
	sc->sc_cmap.cm_map[index][1] = b;
	sc->sc_cmap.cm_map[index][0] = 0;	/* no alpha channel */
	
	cgfourteen_loadcmap_immediate(sc, index, 1);
}

int
cgfourteen_intr(void *v)
{
	struct cgfourteen_softc *sc = v;
	u_int msr;
	int claim = 0;

	msr = sc->sc_ctl->ctl_msr;

	/* check that the interrupt is ours */
	if (!ISSET(msr, CG14_MSR_PENDING) ||
	    !ISSET(sc->sc_ctl->ctl_mctl, CG14_MCTL_ENABLEINTR)) {
		return (0);
	}

	/* vertical retrace interrupt */
	if (ISSET(msr, CG14_MSR_VRETRACE)) {
		/* acknowledge by writing to the (read only) msr */
		sc->sc_ctl->ctl_msr = 0;

		/* disable interrupts until next colormap change */
		sc->sc_ctl->ctl_mctl &= ~CG14_MCTL_ENABLEINTR;

		cgfourteen_loadcmap_immediate(sc,
		    sc->sc_cmap_start, sc->sc_cmap_count);

		claim = 1;
	}

	/* engine fault */
	if (ISSET(msr, CG14_MSR_FAULT)) {
		/* acknowledge by reading the fault status register */
		claim = 1 | sc->sc_ctl->ctl_fsr;
	}

	if (claim == 0) {
#ifdef DEBUG
		printf("%s: unknown interrupt cause, msr=%x\n",
		    sc->sc_sunfb.sf_dev.dv_xname, msr);
#endif
		claim = 1;	/* claim anyway */
	}

	return (claim & 1);
}