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Actually probe for 881 vs. 882. Also add a case for 040, although it's

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really lip-service at the moment.
This commit is contained in:
briggs 1995-05-10 03:19:00 +00:00
parent 5abf82e236
commit 725cb78165
1 changed files with 60 additions and 13 deletions
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73
sys/arch/mac68k/mac68k/fpu.c
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@ -1,4 +1,4 @@
/* $NetBSD: fpu.c,v 1.7 1995/05/06 18:33:19 briggs Exp $ */
/* $NetBSD: fpu.c,v 1.8 1995/05/10 03:19:00 briggs Exp $ */
/*
* Copyright (c) 1995 Gordon W. Ross
@ -31,7 +31,7 @@
*/
/*
* Floating Point Unit (MC68881)
* Floating Point Unit (MC68881/882/040)
* Probe for the FPU at autoconfig time.
*/
@ -50,10 +50,9 @@
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();
extern int matchbyname();
extern int matchbyname __P((struct device *, void *, void *));
static void fpu_attach __P((struct device *, struct device *, void *));
static int fpu_probe __P((void));
struct cfdriver fpucd = {
NULL, "fpu", matchbyname, fpu_attach,
@ -67,9 +66,11 @@ static char *fpu_descr[] = {
#endif
"mc68881", /* 1 */
"mc68882", /* 2 */
"mc68040", /* 3 */
"?" };
void fpu_attach(parent, self, args)
static void
fpu_attach(parent, self, args)
struct device *parent;
struct device *self;
void *args;
@ -86,19 +87,65 @@ void fpu_attach(parent, self, args)
printf(" (%s)\n", descr);
}
int fpu_probe()
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)];
jmp_buf faultbuf;
int null_fpframe[2];
u_char b;
nofault = (int *) &faultbuf;
if (setjmp(nofault)) {
nofault = (int *) 0;
return(0);
}
null_fpframe[0] = 0;
null_fpframe[1] = 0;
m68881_restore(null_fpframe);
/*
* 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;
return(1);
/*
* Presumably, if we're an 040 and did not take exception
* above, we have an FPU. Don't bother probing.
*/
if (cpu040) {
return 3;
}
/*
* 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(fpframe);
/*
* The size of a 68881 IDLE frame is 0x18
* and a 68882 frame is 0x38
*/
if (b == 0x18) return 1;
if (b == 0x38) return 2;
/*
* If it's not one of the above, we have no clue what it is.
*/
return 4;
}