Add a driver that attaches to the gpio node of macio and allows you to enter

DDB when the interrupt button (aka the "programmer's switch") is pressed.

This isn't unfortunately an NMI, but it's a handy way to get into DDB
quickly if needed.

sys/conf/files.powerpc

@@ -73,6 +73,7 @@ powerpc/ofw/ofw_pcib_pci.c	optional	pci
 powerpc/powermac/uninorth.c	optional	powermac pci
 powerpc/powermac/macio.c	optional	powermac pci
 powerpc/powermac/ata_macio.c	optional	powermac ata
+powerpc/powermac/pswitch.c	optional	pswitch powermac
 
 powerpc/psim/iobus.c 		optional psim
 powerpc/psim/ata_iobus.c	optional ata psim

sys/powerpc/powermac/macio.c

@@ -137,7 +137,6 @@ struct macio_quirk_entry {
 static struct macio_quirk_entry macio_quirks[] = {
 	{ "interrupt-controller",	MACIO_QUIRK_IGNORE },
 	{ "escc-legacy",		MACIO_QUIRK_IGNORE },
-	{ "gpio",			MACIO_QUIRK_IGNORE },
 	{ "timer",			MACIO_QUIRK_IGNORE },
 	{ "escc",			MACIO_QUIRK_CHILD_HAS_INTR },
         { NULL,				0 }

sys/powerpc/powermac/pswitch.c

@@ -0,0 +1,143 @@
+/*
+ * Copyright (C) 2002 Benno Rice.
+ * All rights reserved.
+ *
+ * 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 Benno Rice ``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 TOOLS GMBH 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.
+ *
+ * $FreeBSD$
+ */
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/kernel.h>
+#include <sys/malloc.h>
+#include <sys/bus.h>
+#include <machine/bus.h>
+#include <sys/rman.h>
+
+#include <machine/resource.h>
+
+#include <dev/ofw/openfirm.h>
+
+#include <powerpc/powermac/maciovar.h>
+
+struct pswitch_softc {
+	int	sc_irqrid;
+	struct	resource *sc_irq;
+	void	*sc_ih;
+};
+
+static int	pswitch_probe(device_t);
+static int	pswitch_attach(device_t);
+
+static void	pswitch_intr(void *);
+
+static device_method_t pswitch_methods[] = {
+	/* Device interface */
+	DEVMETHOD(device_probe,		pswitch_probe),
+	DEVMETHOD(device_attach,	pswitch_attach),
+
+	{ 0, 0 }
+};
+
+static driver_t pswitch_driver = {
+	"pswitch",
+	pswitch_methods,
+	sizeof(struct pswitch_softc)
+};
+
+static devclass_t pswitch_devclass;
+
+DRIVER_MODULE(pswitch, macio, pswitch_driver, pswitch_devclass, 0, 0);
+
+static int
+pswitch_probe(device_t dev)
+{
+	char	*type = macio_get_devtype(dev);
+
+	if (strcmp(type, "gpio") != 0)
+		return (ENXIO);
+
+	device_set_desc(dev, "GPIO Programmer's Switch");
+	return (0);
+}
+
+static int
+pswitch_attach(device_t dev)
+{
+	struct		pswitch_softc *sc;
+	phandle_t	node, child;
+	char		type[32];
+	u_int		irq[2];
+
+	sc = device_get_softc(dev);
+	node = macio_get_node(dev);
+
+	for (child = OF_child(node); child != 0; child = OF_peer(child)) {
+		if (OF_getprop(child, "device_type", type, 32) == -1)
+			continue;
+
+		if (strcmp(type, "programmer-switch") == 0)
+			break;
+	}
+
+	if (child == 0) {
+		device_printf(dev, "could not find correct node\n");
+		return (ENXIO);
+	}
+
+	if (OF_getprop(child, "interrupts", irq, sizeof(irq)) == -1) {
+		device_printf(dev, "could not get interrupt\n");
+		return (ENXIO);
+	}
+
+	sc->sc_irqrid = 0;
+	sc->sc_irq = bus_alloc_resource(dev, SYS_RES_IRQ, &sc->sc_irqrid,
+	    irq[0], irq[0], 1, RF_ACTIVE);
+	if (sc->sc_irq == NULL) {
+		device_printf(dev, "could not allocate interrupt\n");
+		return (ENXIO);
+	}
+
+	if (bus_setup_intr(dev, sc->sc_irq, INTR_TYPE_MISC | INTR_FAST,
+	    pswitch_intr, dev, &sc->sc_ih) != 0) {
+		device_printf(dev, "could not setup interrupt\n");
+		bus_release_resource(dev, SYS_RES_IRQ, sc->sc_irqrid,
+		    sc->sc_irq);
+		return (ENXIO);
+	}
+
+	return (0);
+}
+
+static void
+pswitch_intr(void *arg)
+{
+	device_t	dev;
+
+	dev = (device_t)arg;
+
+#ifdef DDB
+	Debugger(device_get_nameunit(dev));
+#else
+	device_printf(dev, "close, but no debugger\n");
+#endif
+}