[src/trunk]: src/sys/dev/eisa Don't blindly establish our interrupt handler a...

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

details:   https://anonhg.NetBSD.org/src/rev/476b34ec32ed
branches:  trunk
changeset: 984807:476b34ec32ed
user:      thorpej <thorpej%NetBSD.org@localhost>
date:      Sat Jul 24 15:52:16 2021 +0000

description:
Don't blindly establish our interrupt handler as IST_LEVEL.  If the INTDEF
register has the INTHIGH bit set, the controller is going to keep the
line low when *not* asserting an interrupt, and since EISA level-tiggered
interrupts are active-low, this would result in a forever-interrupt-storm.

So, if INTHIGH is set in INTDEF, establish our interrupt handler as
IST_EDGE, which will program the EISA PIC to detect the interrupt on
the rising edge of the IRQ line.

diffstat:

 sys/dev/eisa/ahb.c |  32 ++++++++++++++++++++++++++------
 1 files changed, 26 insertions(+), 6 deletions(-)

diffs (88 lines):

diff -r 1e46be7cf011 -r 476b34ec32ed sys/dev/eisa/ahb.c
--- a/sys/dev/eisa/ahb.c        Sat Jul 24 15:44:16 2021 +0000
+++ b/sys/dev/eisa/ahb.c        Sat Jul 24 15:52:16 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: ahb.c,v 1.66 2021/04/24 23:36:53 thorpej Exp $ */
+/*     $NetBSD: ahb.c,v 1.67 2021/07/24 15:52:16 thorpej Exp $ */
 
 /*-
  * Copyright (c) 1997, 1998 The NetBSD Foundation, Inc.
@@ -46,7 +46,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: ahb.c,v 1.66 2021/04/24 23:36:53 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: ahb.c,v 1.67 2021/07/24 15:52:16 thorpej Exp $");
 
 #include "opt_ddb.h"
 
@@ -112,6 +112,7 @@
 
 struct ahb_probe_data {
        int sc_irq;
+       int sc_ist;
        int sc_scsi_dev;
 };
 
@@ -251,7 +252,7 @@
                return;
        }
        intrstr = eisa_intr_string(ec, ih, intrbuf, sizeof(intrbuf));
-       sc->sc_ih = eisa_intr_establish(ec, ih, IST_LEVEL, IPL_BIO,
+       sc->sc_ih = eisa_intr_establish(ec, ih, apd.sc_ist, IPL_BIO,
            ahbintr, sc);
        if (sc->sc_ih == NULL) {
                aprint_error_dev(sc->sc_dev, "couldn't establish interrupt");
@@ -260,8 +261,11 @@
                aprint_error("\n");
                return;
        }
-       if (intrstr != NULL)
-               aprint_normal_dev(sc->sc_dev, "interrupting at %s\n", intrstr);
+       if (intrstr != NULL) {
+               aprint_normal_dev(sc->sc_dev,
+                   "interrupting at %s (%s trigger)\n", intrstr,
+                   apd.sc_ist == IST_EDGE ? "edge" : "level");
+       }
 
        /*
         * ask the adapter what subunits are present
@@ -609,7 +613,7 @@
     struct ahb_probe_data *sc)
 {
        u_char intdef;
-       int i, irq, busid;
+       int i, irq, ist, busid;
        int wait = 1000;        /* 1 sec enough? */
 
        bus_space_write_1(iot, ioh, PORTADDR, PORTADDR_ENHANCED);
@@ -676,6 +680,21 @@
                return EIO;
        }
 
+       /*
+        * On EISA, edge triggered interrupts are signalled by the rising
+        * edge of the interrupt signal, while level tiggered interrupts
+        * are signalled so long as the interrupt signal is driven low.
+        *
+        * So, if the controller is configured for active-high interrupts,
+        * that is "edge trigger" in our parlance, while active-low would
+        * be "level trigger".
+        */
+       if (intdef & INTHIGH) {
+               ist = IST_EDGE;
+       } else {
+               ist = IST_LEVEL;
+       }
+
        bus_space_write_1(iot, ioh, INTDEF, (intdef | INTEN));  /* make sure we can interrupt */
 
        /* who are we on the scsi bus? */
@@ -684,6 +703,7 @@
        /* if we want to return data, do so now */
        if (sc) {
                sc->sc_irq = irq;
+               sc->sc_ist = ist;
                sc->sc_scsi_dev = busid;
        }