/* $NetBSD: fpu.c,v 1.25 2008/04/28 20:23:38 martin Exp $ */ /*- * Copyright (c) 1996 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Gordon W. Ross. * * 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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. */ /* * Floating Point Unit (MC68881/882) * Probe for the FPU at autoconfig time. */ #include <sys/cdefs.h> __KERNEL_RCSID(0, "$NetBSD: fpu.c,v 1.25 2008/04/28 20:23:38 martin Exp $"); #include "opt_fpu_emulate.h" #include <sys/param.h> #include <sys/systm.h> #include <machine/cpu.h> #include <machine/frame.h> #include <sun3/sun3/machdep.h> static int fpu_probe(void); static const char *fpu_descr[] = { #ifdef FPU_EMULATE "emulator", /* 0 */ #else "no math support", /* 0 */ #endif "mc68881", /* 1 */ "mc68882", /* 2 */ "mc68040 internal", /* 3 */ "mc68060 internal", /* 4 */ "unknown type" }; /* 5 */ void initfpu(void) { const char *descr; int maxtype = sizeof(fpu_descr) / sizeof(fpu_descr[0]) - 1; /* Set the FPU bit in the "system enable register" */ enable_fpu(1); fputype = fpu_probe(); if (fputype < 0 || fputype > maxtype) fputype = FPU_UNKNOWN; descr = fpu_descr[fputype]; printf("fpu: %s\n", descr); if (fputype == FPU_NONE) { /* Might as well turn the enable bit back off. */ enable_fpu(0); } else m68k_make_fpu_idle_frame(); } static int fpu_probe(void) { label_t faultbuf; struct fpframe fpframe; u_char b; nofault = &faultbuf; if (setjmp(&faultbuf)) { nofault = NULL; return FPU_NONE; } /* * Synchronize FPU or cause a fault. * This should leave the 881/882 in the IDLE state, * so we can determine which we have by * examining the size of the FP state frame. */ __asm("fnop"); nofault = NULL; /* 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("fsave %0@" : : "a" (&fpframe) : "memory"); b = fpframe.fpf_fsize; /* * Now, restore a NULL state to reset the FPU. */ fpframe.fpf_null = 0; fpframe.fpf_idle.fpf_ccr = 0; m68881_restore(&fpframe); /* * The size of a 68881 IDLE frame is 0x18 * and 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; }