174 lines
4.5 KiB
C
174 lines
4.5 KiB
C
/* $NetBSD: fpu.c,v 1.21 1996/12/16 16:17:16 scottr Exp $ */
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/*-
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* Copyright (c) 1996 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Gordon W. Ross.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the NetBSD
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* Foundation, Inc. and its contributors.
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* 4. Neither the name of The NetBSD Foundation nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* Floating Point Unit (MC68881/882/040)
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* Probe for the FPU at autoconfig time.
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/time.h>
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#include <sys/kernel.h>
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#include <sys/device.h>
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#include <machine/psl.h>
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#include <machine/cpu.h>
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#include <machine/frame.h>
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/*
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* FPU type; emulator uses FPU_NONE
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*/
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int fputype;
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extern int *nofault;
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static int fpu_match __P((struct device *, struct cfdata *, void *));
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static void fpu_attach __P((struct device *, struct device *, void *));
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static int fpu_probe __P((void));
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struct cfattach fpu_ca = {
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sizeof(struct device), fpu_match, fpu_attach
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};
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struct cfdriver fpu_cd = {
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NULL, "fpu", DV_DULL, 0
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};
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static int
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fpu_match(parent, cf, aux)
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struct device *parent;
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struct cfdata *cf;
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void *aux;
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{
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return 1;
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}
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static char *fpu_descr[] = {
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#ifdef FPU_EMULATE
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"emulator", /* 0 */
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#else
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"no math support", /* 0 */
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#endif
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"mc68881", /* 1 */
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"mc68882", /* 2 */
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"mc68040", /* 3 */
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"mc68060", /* 4 */
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"unknown" };
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static void
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fpu_attach(parent, self, args)
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struct device *parent;
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struct device *self;
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void *args;
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{
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char *descr;
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fputype = fpu_probe();
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if ((0 <= fputype) && (fputype <= 3))
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descr = fpu_descr[fputype];
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else
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descr = "unknown type";
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printf(" (%s)\n", descr);
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}
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static int
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fpu_probe()
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{
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/*
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* A 68881 idle frame is 28 bytes and a 68882's is 60 bytes.
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* We, of course, need to have enough room for either.
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*/
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int fpframe[60 / sizeof(int)];
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label_t faultbuf;
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u_char b;
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nofault = (int *) &faultbuf;
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if (setjmp(&faultbuf)) {
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nofault = (int *) 0;
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return (FPU_NONE);
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}
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/*
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* Synchronize FPU or cause a fault.
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* This should leave the 881/882 in the IDLE state,
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* state, so we can determine which we have by
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* examining the size of the FP state frame
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*/
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asm("fnop");
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nofault = (int *) 0;
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/*
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* Presumably, if we're an 040 and did not take exception
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* above, we have an FPU. Don't bother probing.
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*/
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if (mmutype == MMU_68040)
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return (FPU_68040);
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/*
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* Presumably, this will not cause a fault--the fnop should
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* have if this will. We save the state in order to get the
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* size of the frame.
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*/
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asm("movl %0, a0; fsave a0@" : : "a" (fpframe) : "a0" );
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b = *((u_char *) fpframe + 1);
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/*
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* Now, restore a NULL state to reset the FPU.
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*/
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fpframe[0] = fpframe[1] = 0;
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m68881_restore((struct fpframe *) fpframe);
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/*
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* The size of a 68881 IDLE frame is 0x18
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* and a 68882 frame is 0x38
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*/
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if (b == 0x18)
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return (FPU_68881);
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if (b == 0x38)
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return (FPU_68882);
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/*
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* If it's not one of the above, we have no clue what it is.
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*/
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return (FPU_UNKNOWN);
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}
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