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/* $OpenBSD: fpu.c,v 1.5 1996/10/14 01:15:52 briggs Exp $ */
/* $NetBSD: fpu.c,v 1.16 1996/06/11 02:56:22 scottr 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 (MC68881/882/040)
* 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/psl.h>
#include <machine/cpu.h>
#include <machine/frame.h>
/*
* FPU type; emulator uses FPU_NONE
*/
int fputype;
extern int *nofault;
static int fpu_match __P((struct device *, void *, void *));
static void fpu_attach __P((struct device *, struct device *, void *));
static int fpu_probe __P((void));
struct cfattach fpu_ca = {
sizeof(struct device), fpu_match, fpu_attach
};
struct cfdriver fpu_cd = {
NULL, "fpu", DV_DULL, 0
};
static int
fpu_match(pdp, match, auxp)
struct device *pdp;
void *match, *auxp;
{
return 1;
}
static char *fpu_descr[] = {
#ifdef FPU_EMULATE
"emulator", /* 0 */
#else
"no math support", /* 0 */
#endif
"mc68881", /* 1 */
"mc68882", /* 2 */
"mc68040", /* 3 */
"mc68060", /* 4 */
"unknown" };
static void
fpu_attach(parent, self, args)
struct device *parent;
struct device *self;
void *args;
{
char *descr;
fputype = fpu_probe();
if ((0 <= fputype) && (fputype <= 3))
descr = fpu_descr[fputype];
else
descr = "unknown type";
printf(" (%s)\n", descr);
}
static int
fpu_probe()
{
/*
* A 68881 idle frame is 28 bytes and a 68882's is 60 bytes.
* We, of course, need to have enough room for either.
*/
int fpframe[60 / sizeof(int)];
label_t faultbuf;
u_char b;
nofault = (int *) &faultbuf;
if (setjmp(&faultbuf)) {
nofault = (int *) 0;
return (FPU_NONE);
}
/*
* Synchronize FPU or cause a fault.
* This should leave the 881/882 in the IDLE state,
* state, so we can determine which we have by
* examining the size of the FP state frame
*/
asm("fnop");
nofault = (int *) 0;
/*
* Presumably, if we're an 040 and did not take exception
* above, we have an FPU. Don't bother probing.
*/
if (mmutype == MMU_68040)
return (FPU_68040);
/*
* Presumably, this will not cause a fault--the fnop should
* have if this will. We save the state in order to get the
* size of the frame.
*/
asm("movl %0, a0; fsave a0@" : : "a" (fpframe) : "a0" );
b = *((u_char *) fpframe + 1);
/*
* Now, restore a NULL state to reset the FPU.
*/
fpframe[0] = fpframe[1] = 0;
m68881_restore((struct fpframe *) fpframe);
/*
* The size of a 68881 IDLE frame is 0x18
* and a 68882 frame is 0x38
*/
if (b == 0x18)
return (FPU_68881);
if (b == 0x38)
return (FPU_68882);
/*
* If it's not one of the above, we have no clue what it is.
*/
return (FPU_UNKNOWN);
}
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