Some rpmsg backends support holding on to and redelivering messages upon
failed handling of them, so provide a way for the callback to report and
error and allow the backends to handle this.
Signed-off-by: NBjorn Andersson <bjorn.andersson@linaro.org>

Move virtio rpmsg implementation details from the public header file to
the virtio rpmsg implementation.
Signed-off-by: NBjorn Andersson <bjorn.andersson@linaro.org>

Create a container struct virtio_rpmsg_channel around the rpmsg_channel
to keep virtio backend information separate from the rpmsg and public
API. This makes the public structures independant of virtio.
Signed-off-by: NBjorn Andersson <bjorn.andersson@linaro.org>

Move the device and endpoint indirection tables to the rpmsg internal
header file, to hide them from the public API.
Signed-off-by: NBjorn Andersson <bjorn.andersson@linaro.org>

Move the rpmsg_send() and rpmsg_destroy_ept() interface to the rpmsg
core, so that we eventually can hide the rpmsg_endpoint ops from the
public API.
Signed-off-by: NBjorn Andersson <bjorn.andersson@linaro.org>

Add indirection table for rpmsg_endpoint related operations and move
virtio implementation behind this, this finishes of the decoupling of
the virtio implementation from the public API.
Signed-off-by: NBjorn Andersson <bjorn.andersson@linaro.org>

To allow for multiple backend implementations add an indireection table
for rpmsg_device related operations and move the virtio implementation
behind this table.
Signed-off-by: NBjorn Andersson <bjorn.andersson@linaro.org>

The rpmsg device representing struct is called rpmsg_channel and the
variable name used throughout is rpdev, with the communication happening
on endpoints it's clearer to just call this a "device" in a public API.
Signed-off-by: NBjorn Andersson <bjorn.andersson@linaro.org>

As we introduce support for additional rpmsg backends, some of these
only supports point-to-point "links" represented by a name. By making
rpmsg_create_ept() take a channel_info struct we allow for these
backends to either be passed a source address, a destination address or
a name identifier.
Signed-off-by: NBjorn Andersson <bjorn.andersson@linaro.org>

The rpmsg_send() operations has been taking a rpmsg_device, but this
forces users of secondary rpmsg_endpoints to use the rpmsg_sendto()
interface - by extracting source and destination from the given data
structures. If we instead pass the rpmsg_endpoint to these functions a
service can use rpmsg_sendto() to respond to messages, even on secondary
endpoints.

In addition this would allow us to support operations on multiple
channels in future backends that does not support off-channel
operations.
Signed-off-by: NBjorn Andersson <bjorn.andersson@linaro.org>

The (un)register_rpmsg_device() functions never made it to mainline, so
drop them for now.
Signed-off-by: NBjorn Andersson <bjorn.andersson@linaro.org>

This patch fixes most of the existing alignment checkpatch check
warnings of the type "Alignment should match open parenthesis"
in the virtio rpmsg bus code. A couple of them have been left as
is to not exceed the 80-char limit.
Signed-off-by: NSuman Anna <s-anna@ti.com>
Signed-off-by: NBjorn Andersson <bjorn.andersson@linaro.org>

This patch introduces the module_rpmsg_driver macro which is a
convenience macro for rpmsg driver modules similar to
module_platform_driver. It is intended to be used by drivers which
init/exit section does nothing but register/unregister the rpmsg driver.
By using this macro it is possible to eliminate a few lines of
boilerplate code per rpmsg driver.
Signed-off-by: NAndrew F. Davis <afd@ti.com>
Signed-off-by: NBjorn Andersson <bjorn.andersson@linaro.org>

Add register_rpmsg_driver helper macro that adds THIS_MODULE to
rpmsg_driver for the registering driver. We rename and modify
the existing register_rpmsg_driver to enable this.
Signed-off-by: NAndrew F. Davis <afd@ti.com>
Acked-by: NSuman Anna <s-anna@ti.com>
Signed-off-by: NBjorn Andersson <bjorn.andersson@linaro.org>

When inbound messages arrive, rpmsg core looks up their associated
endpoint (by destination address) and then invokes their callback.

We've made sure that endpoints will never be de-allocated after they
were found by rpmsg core, but we also need to protect against the
(rare) scenario where the rpmsg driver was just removed, and its
callback function isn't available anymore.

This is achieved by introducing a callback mutex, which must be taken
before the callback is invoked, and, obviously, before it is removed.

Cc: stable <stable@vger.kernel.org>
Reported-by: NFernando Guzman Lugo <fernando.lugo@ti.com>
Signed-off-by: NOhad Ben-Cohen <ohad@wizery.com>

When an inbound message arrives, the rpmsg core looks up its
associated endpoint and invokes the registered callback.

If a message arrives while its endpoint is being removed (because
the rpmsg driver was removed, or a recovery of a remote processor
has kicked in) we must ensure atomicity, i.e.:

- Either the ept is removed before it is found

or

- The ept is found but will not be freed until the callback returns

This is achieved by maintaining a per-ept reference count, which,
when drops to zero, will trigger deallocation of the ept.

With this in hand, it is now forbidden to directly deallocate
epts once they have been added to the endpoints idr.

Cc: stable <stable@vger.kernel.org>
Reported-by: NFernando Guzman Lugo <fernando.lugo@ti.com>
Signed-off-by: NOhad Ben-Cohen <ohad@wizery.com>

Add a virtio-based inter-processor communication bus, which enables
kernel drivers to communicate with entities, running on remote
processors, over shared memory using a simple messaging protocol.

Every pair of AMP processors share two vrings, which are used to send
and receive the messages over shared memory.

The header of every message sent on the rpmsg bus contains src and dst
addresses, which make it possible to multiplex several rpmsg channels on
the same vring.

Every rpmsg channel is a device on this bus. When a channel is added,
and an appropriate rpmsg driver is found and probed, it is also assigned
a local rpmsg address, which is then bound to the driver's callback.

When inbound messages carry the local address of a bound driver,
its callback is invoked by the bus.

This patch provides a kernel interface only; user space interfaces
will be later exposed by kernel users of this rpmsg bus.

Designed with Brian Swetland <swetland@google.com>.
Signed-off-by: NOhad Ben-Cohen <ohad@wizery.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au> (virtio_ids.h)
Cc: Brian Swetland <swetland@google.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg KH <greg@kroah.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>