/*	$NetBSD: fpu.c,v 1.1 1995/03/24 17:27:37 gwr Exp $	*/

/*
 * Copyright (c) 1995 Gordon W. Ross
 * 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. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 * 4. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Gordon Ross
 *
 * 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.
 */

/*
 * Floating Point Unit (MC68881)
 * Probe for the FPU at autoconfig time.
 */

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

#include <machine/autoconf.h>
#include <machine/psl.h>
#include <machine/cpu.h>
#include <machine/frame.h>
#include <machine/mon.h>
#include <machine/control.h>

#include <setjmp.h>

#include "interreg.h"

extern int fpu_type;
extern int *nofault;

int fpu_match __P((struct device *, void *vcf, void *args));
void fpu_attach __P((struct device *, struct device *, void *));
int fpu_probe();

struct cfdriver fpucd = {
	NULL, "fpu", fpu_match, fpu_attach,
	DV_DULL, sizeof(struct device), 0 };

int fpu_match(parent, vcf, args)
    struct device *parent;
    void *vcf, *args;
{
    struct cfdata *cf = vcf;
	struct confargs *ca = args;

	/* This driver only supports one unit. */
	if (cf->cf_unit != 0)
		return (0);

	return (1);
}

static char *fpu_descr[] = {
#ifdef	FPU_EMULATE
	"emulator", 		/* 0 */
#else
	"no math support",	/* 0 */
#endif
	"mc68881",			/* 1 */
	"mc68882",			/* 2 */
	"?" };

void fpu_attach(parent, self, args)
	struct device *parent;
	struct device *self;
	void *args;
{
	struct confargs *ca = args;
	char *descr;
	int enab_reg;

	/* Set the FPU bit in the "system enable register" */
	enab_reg = get_control_byte((char *) SYSTEM_ENAB);
	enab_reg |= SYSTEM_ENAB_FPP;
	set_control_byte((char *) SYSTEM_ENAB, enab_reg);

	fpu_type = fpu_probe();
	if ((0 <= fpu_type) && (fpu_type <= 2))
		descr = fpu_descr[fpu_type];
	else
		descr = "unknown type";

	printf(" (%s)\n", descr);

	if (fpu_type == 0) {
		/* Might as well turn the enable bit back off. */
		enab_reg = get_control_byte((char *) SYSTEM_ENAB);
		enab_reg &= ~SYSTEM_ENAB_FPP;
		set_control_byte((char *) SYSTEM_ENAB, enab_reg);
	}
}

int fpu_probe()
{
	jmp_buf	faultbuf;
	int null_fpframe[2];

	nofault = (int *) &faultbuf;
	if (setjmp(nofault)) {
		nofault = (int *) 0;
		return(0);
	}
	null_fpframe[0] = 0;
	null_fpframe[1] = 0;
	m68881_restore(null_fpframe);
	nofault = (int *) 0;
	return(1);
}