[src/trunk]: src/sys/arch/arm Query the media and vfp feature registers to de...

[matt <matt%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/aa172c5365a7
branches:  trunk
changeset: 793997:aa172c5365a7
user:      matt <matt%NetBSD.org@localhost>
date:      Mon Mar 03 08:45:18 2014 +0000

description:
Query the media and vfp feature registers to determine what our default
mode should be and what bits in the fpscr can be changed.
Print what features are supported:
vfp0 at cpu0: NEON MPE (VFP 3.0+), rounding, NaN propogation, denormals

diffstat:

 sys/arch/arm/arm32/sys_machdep.c |   7 +++--
 sys/arch/arm/vfp/vfp_init.c      |  46 +++++++++++++++++++++++++++++----------
 2 files changed, 38 insertions(+), 15 deletions(-)

diffs (116 lines):

diff -r 45368dad37a3 -r aa172c5365a7 sys/arch/arm/arm32/sys_machdep.c
--- a/sys/arch/arm/arm32/sys_machdep.c  Mon Mar 03 08:15:36 2014 +0000
+++ b/sys/arch/arm/arm32/sys_machdep.c  Mon Mar 03 08:45:18 2014 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: sys_machdep.c,v 1.19 2013/08/23 14:39:50 matt Exp $    */
+/*     $NetBSD: sys_machdep.c,v 1.20 2014/03/03 08:45:18 matt Exp $    */
 
 /*
  * Copyright (c) 1995-1997 Mark Brinicombe.
@@ -41,7 +41,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: sys_machdep.c,v 1.19 2013/08/23 14:39:50 matt Exp $");
+__KERNEL_RCSID(0, "$NetBSD: sys_machdep.c,v 1.20 2014/03/03 08:45:18 matt Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -106,11 +106,12 @@
 
        retval[0] = pcb->pcb_vfp.vfp_fpscr;
        if (uap) {
+               extern uint32_t vfp_fpscr_changable;
                struct arm_vfp_fpscr_args ua;
                int error;
                if ((error = copyin(uap, &ua, sizeof(ua))) != 0)
                        return (error);
-               if (((ua.fpscr_clear|ua.fpscr_set) & ~VFP_FPSCR_RMODE) != 0)
+               if ((ua.fpscr_clear|ua.fpscr_set) & ~vfp_fpscr_changable)
                        return EINVAL;
                pcb->pcb_vfp.vfp_fpscr &= ~ua.fpscr_clear;
                pcb->pcb_vfp.vfp_fpscr |= ua.fpscr_set;
diff -r 45368dad37a3 -r aa172c5365a7 sys/arch/arm/vfp/vfp_init.c
--- a/sys/arch/arm/vfp/vfp_init.c       Mon Mar 03 08:15:36 2014 +0000
+++ b/sys/arch/arm/vfp/vfp_init.c       Mon Mar 03 08:45:18 2014 +0000
@@ -1,4 +1,4 @@
-/*      $NetBSD: vfp_init.c,v 1.33 2014/01/25 17:30:56 skrll Exp $ */
+/*      $NetBSD: vfp_init.c,v 1.34 2014/03/03 08:45:18 matt Exp $ */
 
 /*
  * Copyright (c) 2008 ARM Ltd
@@ -148,6 +148,11 @@
 struct evcnt vfpevent_reuse;
 struct evcnt vfpevent_fpe;
 
+/* determine what bits can be changed */
+uint32_t vfp_fpscr_changable = VFP_FPSCR_CSUM;
+/* default to run fast */
+uint32_t vfp_fpscr_default = (VFP_FPSCR_DN | VFP_FPSCR_FZ | VFP_FPSCR_RN);
+
 /*
  * Used to test for a VFP. The following function is installed as a coproc10
  * handler on the undefined instruction vector and then we issue a VFP
@@ -208,10 +213,8 @@
        if (insn & 0x00100000) {
                *regp = pcb->pcb_vfp.vfp_fpscr;
        } else {
-               register_t tmp = *regp;
-               if (!(cpu_media_and_vfp_features[0] & ARM_MVFR0_EXCEPT_MASK))
-                       tmp &= ~VFP_FPSCR_ESUM;
-               pcb->pcb_vfp.vfp_fpscr = tmp;
+               pcb->pcb_vfp.vfp_fpscr &= ~vfp_fpscr_changable;
+               pcb->pcb_vfp.vfp_fpscr |= *regp & vfp_fpscr_changable;
        }
 
        vfp_fpscr_ev.ev_count++;
@@ -345,14 +348,34 @@
        cpu_media_and_vfp_features[0] = armreg_mvfr0_read();
        cpu_media_and_vfp_features[1] = armreg_mvfr1_read();
        if (fpsid != 0) {
-               aprint_normal("vfp%d at %s: %s\n",
+               uint32_t f0 = armreg_mvfr0_read();
+               uint32_t f1 = armreg_mvfr0_read();
+               aprint_normal("vfp%d at %s: %s%s%s%s%s\n",
                    device_unit(curcpu()->ci_dev),
                    device_xname(curcpu()->ci_dev),
-                   model);
+                   model,
+                   ((f0 & ARM_MVFR0_ROUNDING_MASK) ? ", rounding" : ""),
+                   ((f0 & ARM_MVFR0_EXCEPT_MASK) ? ", exceptions" : ""),
+                   ((f1 & ARM_MVFR1_D_NAN_MASK) ? ", NaN propogation" : ""),
+                   ((f1 & ARM_MVFR1_FTZ_MASK) ? ", denormals" : ""));
                aprint_verbose("vfp%d: mvfr: [0]=%#x [1]=%#x\n",
-                   device_unit(curcpu()->ci_dev), 
-                   cpu_media_and_vfp_features[0],
-                   cpu_media_and_vfp_features[1]);
+                   device_unit(curcpu()->ci_dev), f0, f1);
+               if (cpu_media_and_vfp_features[0] & ARM_MVFR0_ROUNDING_MASK) {
+                       vfp_fpscr_changable |= VFP_FPSCR_RMODE;
+               }
+               if (cpu_media_and_vfp_features[0] & ARM_MVFR0_EXCEPT_MASK) {
+                       vfp_fpscr_changable |= VFP_FPSCR_ESUM;
+               }
+               // If hardware supports propogation of NaNs, select it.
+               if (cpu_media_and_vfp_features[1] & ARM_MVFR1_D_NAN_MASK) {
+                       vfp_fpscr_default &= ~VFP_FPSCR_DN;
+                       vfp_fpscr_changable |= VFP_FPSCR_DN;
+               }
+               // If hardware supports denormalized numbers, use it.
+               if (cpu_media_and_vfp_features[1] & ARM_MVFR1_FTZ_MASK) {
+                       vfp_fpscr_default &= ~VFP_FPSCR_FZ;
+                       vfp_fpscr_changable |= VFP_FPSCR_FZ;
+               }
        }
        evcnt_attach_dynamic(&vfpevent_use, EVCNT_TYPE_MISC, NULL,
            "VFP", "coproc use");
@@ -505,8 +528,7 @@
        if (__predict_false((flags & PCU_LOADED) == 0)) {
                KASSERT(flags & PCU_RELOAD);
                vfpevent_use.ev_count++;
-               pcb->pcb_vfp.vfp_fpscr =
-                   (VFP_FPSCR_DN | VFP_FPSCR_FZ | VFP_FPSCR_RN); /* Runfast */
+               pcb->pcb_vfp.vfp_fpscr = vfp_fpscr_default;
        } else {
                vfpevent_reuse.ev_count++;
        }