accel/habanalabs: Allow single timestamp registration request at a time

Protect against concurrency of user requesting to register a timestamp
offset (where the driver fills the timestamp when the command submission
has finished executing) to a specific user interrupt ID. The
protection is basically to allow only one timestamp registration
request to be handled at a time.

This is needed because the user can decide to re-use a timestamp
offset (register an already registered offset, to a different
interrupt ID). This means the request will cause the timestamp node to
move from one interrupt list to another interrupt list. In such
scenario, without proper protection, we could end up adding the same
node twice to the interrupts wait lists.

Signed-off-by: farah kassabri <fkassabri@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>

accel/habanalabs: print task name upon creation of a user context

It is useful for debug to know which user process have acquired the
device.
Add this info to the relevant debug print, in addition to the already
printed user context's ASID.

Signed-off-by: Tomer Tayar <ttayar@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>

habanalabs: move driver to accel subsystem

Now that we have a subsystem for compute accelerators, move the
habanalabs driver to it.

This patch only moves the files and fixes the Makefiles. Future
patches will change the existing code to register to the accel
subsystem and expose the accel device char files instead of the
habanalabs device char files.

Update the MAINTAINERS file to reflect this change.

Signed-off-by: Oded Gabbay <ogabbay@kernel.org>