tree 140cfeea7a9de27387285ff4c4fc7c3728758034
parent 06e7bd1f9bd86a47e1824f02a821b198eafeb7b6
author Paul Gortmaker <paul.gortmaker@windriver.com> 1444777590 -0400
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1445141910 -0700

tty: disable unbind for old 74xx based serial/mpsc console port

We recently got rid of some modular code in this driver and also
got rid of the unused ".remove" function at the same time.  Thierry
noted that it was however possible to force the remove through the
bind/unbind interface.

Since this is a console device used on 2005 vintage 74xx based
powerpc embedded targets, and is essentially always used in
conjunction with SERIAL_MPSC_CONSOLE=y -- there is no sane reason
anyone would ever want to unbind the builtin driver and lose the
console.  So we just explicitly block bind/unbind operations and
prevent root from shooting themselves in the foot.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: linux-serial@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>