Post by Okash Khawajaenable acess to tty device from kernel module
You need much more explanations, and also this is based on a patch from
Alan Cox
(http://www.mail-archive.com/linux-***@vger.kernel.org/msg1215095.html),
so you should integrate the explanations, something like:
“
tty_port: allow a port to be opened with a tty that has no file handle
Let us create tty objects entirely in kernel space.
With this a kernel created non file backed tty object could be used to handle
data, and set terminal modes. Not all ldiscs can cope with this as N_TTY in
particular has to work back to the fs/tty layer.
The tty_port code is however otherwise clean of file handles as far as I can
tell as is the low level tty port write path used by the ldisc, the
configuration low level interfaces and most of the ldiscs.
Currently you don't have any exposure to see tty hangups because those are
built around the file layer. However a) it's a fixed port so you probably
don't care about that b) if you do we can add a callback and c) you almost
certainly don't want the userspace tear down/rebuild behaviour anyway.
This should however be sufficient if we wanted for example to enumerate all
the bluetooth bound fixed ports via ACPI and make them directly available.
It doesn't deal with the case of a user opening a port that's also kernel
opened and that would need some locking out (so it returned EBUSY if bound
to a kernel device of some kind). That needs resolving along with how you
"up" or "down" your new bluetooth device, or enumerate it while providing
the existing tty API to avoid regressions (and to debug).
”
You'll need to have Alan Cox in Cc when actually submitting the patch,
so he gets to comment on it. You'll then have to add your Signed-off-By
along his own, see linux/Documentation/SubmittingPatches for the
details.
Samuel