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, 6 insertions, 5 deletions

diff --git a/sys/dev/atkbdc/atkbd.c b/sys/dev/atkbdc/atkbd.c
index eedc469..9987787 100644
--- a/sys/dev/atkbdc/atkbd.c
+++ b/sys/dev/atkbdc/atkbd.c
@@ -282,11 +282,12 @@ atkbd_configure(int flags)
 	int arg[2];
 	int i;
 
-	/* probe the keyboard controller */
-	atkbdc_configure();
-
-	/* if the driver is disabled, unregister the keyboard if any */
-	if (resource_disabled("atkbd", ATKBD_DEFAULT)) {
+	/*
+	 * Probe the keyboard controller, if not present or if the driver
+	 * is disabled, unregister the keyboard if any.
+	 */
+	if (atkbdc_configure() != 0 ||
+	    resource_disabled("atkbd", ATKBD_DEFAULT)) {
 		i = kbd_find_keyboard(ATKBD_DRIVER_NAME, ATKBD_DEFAULT);
 		if (i >= 0) {
 			kbd = kbd_get_keyboard(i);