[src/trunk]: src/sys/arch/powerpc/ibm4xx Fix hard freeze in pic_handle_intr()...

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

details:   https://anonhg.NetBSD.org/src/rev/9981bdb4a730
branches:  trunk
changeset: 953292:9981bdb4a730
user:      rin <rin%NetBSD.org@localhost>
date:      Fri Mar 05 05:35:50 2021 +0000

description:
Fix hard freeze in pic_handle_intr() for PPC_IBM403.

Not clearly documented in reference manual, but DCR_EXISR register is
not updated immediately after some bits are cleared by mtdcr, no matter
whether sync (= eieio) and/or isync are issued.

Therefore, we have to manage our own status mask in the interrupt handler.
This is what we did in obsoleted powerpc/ibm4xx/intr.c.

With this change, my Explora 451 works just fine with serial console!
Fix for framebuffer console will be committed soon.

diffstat:

 sys/arch/powerpc/ibm4xx/pic_uic.c |  30 +++++++++++++++++++++++++++---
 1 files changed, 27 insertions(+), 3 deletions(-)

diffs (66 lines):

diff -r dd0b3ee2fa54 -r 9981bdb4a730 sys/arch/powerpc/ibm4xx/pic_uic.c
--- a/sys/arch/powerpc/ibm4xx/pic_uic.c Fri Mar 05 02:58:13 2021 +0000
+++ b/sys/arch/powerpc/ibm4xx/pic_uic.c Fri Mar 05 05:35:50 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: pic_uic.c,v 1.8 2021/02/27 20:43:58 rin Exp $  */
+/*     $NetBSD: pic_uic.c,v 1.9 2021/03/05 05:35:50 rin Exp $  */
 
 /*
  * Copyright 2002 Wasabi Systems, Inc.
@@ -36,7 +36,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: pic_uic.c,v 1.8 2021/02/27 20:43:58 rin Exp $");
+__KERNEL_RCSID(0, "$NetBSD: pic_uic.c,v 1.9 2021/03/05 05:35:50 rin Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_ppcarch.h"
@@ -73,6 +73,19 @@
 
 struct uic {
        uint32_t uic_intr_enable;       /* cached intr enable mask */
+#ifdef PPC_IBM403
+       /*
+        * Not clearly documented in reference manual, but DCR_EXISR
+        * register is not updated immediately after some bits are
+        * cleared by mtdcr, no matter whether sync (= eieio) and/or
+        * isync are issued.
+        *
+        * Therefore, we have to manage our own status mask in the
+        * interrupt handler; see uic_{ack,get}_irq() for more details.
+        * This is what we did in obsoleted powerpc/ibm4xx/intr.c.
+        */
+       uint32_t uic_intr_status;
+#endif
        uint32_t (*uic_mf_intr_status)(void);
        uint32_t (*uic_mf_intr_enable)(void);
        void (*uic_mt_intr_enable)(uint32_t);
@@ -356,15 +369,26 @@
        struct uic * const uic = pic->pic_cookie;
        const uint32_t irqmask = IRQ_TO_MASK(irq);
 
+#ifdef PPC_IBM403
+       uic->uic_intr_status &= ~irqmask;
+#endif
+
        (*uic->uic_mt_intr_ack)(irqmask);
 }
 
 static int
-uic_get_irq(struct pic_ops *pic, int dummy)
+uic_get_irq(struct pic_ops *pic, int req)
 {
        struct uic * const uic = pic->pic_cookie;
 
+#ifdef PPC_IBM403
+       if (req == PIC_GET_IRQ)
+               uic->uic_intr_status = (*uic->uic_mf_intr_status)();
+       const uint32_t irqmask = uic->uic_intr_status;
+#else
        const uint32_t irqmask = (*uic->uic_mf_intr_status)();
+#endif
+
        if (irqmask == 0)
                return 255;
        return IRQ_OF_MASK(irqmask);