Use the same method for detecting actual presence of AT-style keyboard

controller as we use in boot blocks (querying status register until
bit 1 goes off). If that doesn't happed during reasonable period assume
that the hardware doesn't have AT-style keyboard controller. This makes
FreeBSD working almost OOB on MacBook Pro (still there are issues with
putting second CPU core on-line, but since installation CD comes with
UP kernel with this change one should be able to install FreeBSD without
playing tricks with hints). Other legacy-free hardware (e.g. IBM NetVista
S40) should benefit from this as well, but since I don't have any I can't
verify.

It should make no difference on the ordinary i386 hardware (since in
that case that hardware already would be having an issues with A20
routines in boot blocks). I don't know much about AT-style keyboard
controller on other platforms (and don't have dedicated access to one),
therefore, the code is restricted to i386 for now. I suspect that amd64
may need this as well, but I would rather leave this decision to someone
who knows better about the platform(s) in question.

I have tested this change on as many "ordinary i386 boxes" as I can get
my hands on, and it doesn't create any false negatives on hardware with
AT-style keyboard present.

MFC after:	1 month

1 files changed, 31 insertions, 0 deletions

diff --git a/sys/dev/atkbdc/atkbdc_isa.c b/sys/dev/atkbdc/atkbdc_isa.c
index deeb7a0..96abfb5 100644
--- a/sys/dev/atkbdc/atkbdc_isa.c
+++ b/sys/dev/atkbdc/atkbdc_isa.c
@@ -93,6 +93,12 @@ atkbdc_isa_probe(device_t dev)
 	u_long		count;
 	int		error;
 	int		rid;
+#if defined(__i386__)
+	bus_space_tag_t	tag;
+	bus_space_handle_t ioh1;
+	volatile int	i;
+	register_t	flags;
+#endif
 
 	/* check PnP IDs */
 	if (ISA_PNP_PROBE(device_get_parent(dev), dev, atkbdc_ids) == ENXIO)
@@ -127,6 +133,31 @@ atkbdc_isa_probe(device_t dev)
 		bus_release_resource(dev, SYS_RES_IOPORT, 0, port0);
 		return ENXIO;
 	}
+
+#if defined(__i386__)
+	/*
+	 * Check if we really have AT keyboard controller. Poll status
+	 * register until we get "all clear" indication. If no such
+	 * indication comes, it probably means that there is no AT
+	 * keyboard controller present. Give up in such case. Check relies
+	 * on the fact that reading from non-existing in/out port returns
+	 * 0xff on i386. May or may not be true on other platforms.
+	 */
+	tag = rman_get_bustag(port0);
+	ioh1 = rman_get_bushandle(port1);
+	flags = intr_disable();
+	for (i = 0; i != 65535; i++) {
+		if ((bus_space_read_1(tag, ioh1, 0) & 0x2) == 0)
+			break;
+	}
+	intr_restore(flags);
+	if (i == 65535) {
+		bus_release_resource(dev, SYS_RES_IOPORT, 0, port0);
+		bus_release_resource(dev, SYS_RES_IOPORT, 1, port1);
+		return ENXIO;
+	}
+#endif
+
 	device_verbose(dev);
 
 	error = atkbdc_probe_unit(device_get_unit(dev), port0, port1);