The ffa_linux_errmap buffer access index is supposed to range from 0-8
but it ranges from 1-9 instead. It reads one element out of bounds. It
also changes the success into -EINVAL though ffa_to_linux_errno is never
used in case of success, it is expected to work for success case too.

It is slightly confusing code as the negative of the error code
is used as index to the buffer. Fix it by negating it at the start and
make it more readable.

Link: https://lore.kernel.org/r/20210707134739.1869481-1-sudeep.holla@arm.com
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

clang produces the following warning:

    drivers/firmware/arm_ffa/driver.c:123: warning: expecting
    prototype for FF(). Prototype was for FFA_PAGE_SIZE() instead

    This comment starts with '/**', but isn't a kernel-doc comment.
    Refer Documentation/doc-guide/kernel-doc.rst

Fix the same by removing the kernel-doc style comment here.

Link: https://lore.kernel.org/r/20210622162202.3485866-1-sudeep.holla@arm.com
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

When the driver core calls the probe callback it already checked that
the devices match, so there is no need to call the match callback again.

Link: https://lore.kernel.org/r/20210621201652.127611-2-u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

The bus probe callback calls the driver callback without further
checking. Better be safe than sorry and refuse registration of a driver
without a probe function to prevent a NULL pointer exception.

Link: https://lore.kernel.org/r/20210621201652.127611-1-u.kleine-koenig@pengutronix.de
Fixes: e781858488b9 ("firmware: arm_ffa: Add initial FFA bus support for device enumeration")
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

Most of the MEM_* APIs share the same parameters, so they can be
generalised. Currently only MEM_SHARE is implemented and the user space
interface for that is not added yet.

Link: https://lore.kernel.org/r/20210521151033.181846-6-sudeep.holla@arm.com
Tested-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

Parse the FFA nodes from the device-tree and register all the partitions
whose services will be used in the kernel.

In order to also enable in-kernel users of FFA interface, let us add
simple set of operations for such devices.

The in-kernel users are registered without the character device interface.

Link: https://lore.kernel.org/r/20210521151033.181846-5-sudeep.holla@arm.com
Tested-by: Jens Wiklander <jens.wiklander@linaro.org>
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

There are requests to keep the transport separate in order to allow
other possible transports like virtio. So let us keep the SMCCC transport
specific routines abstracted.

It is kept simple for now. Once we add another transport, we can develop
better abstraction.

Link: https://lore.kernel.org/r/20210521151033.181846-4-sudeep.holla@arm.com
Tested-by: Jens Wiklander <jens.wiklander@linaro.org>
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

This just add a basic driver that sets up the transport(e.g. SMCCC),
checks the FFA version implemented, get the partition ID for self and
sets up the Tx/Rx buffers for communication.

Link: https://lore.kernel.org/r/20210521151033.181846-3-sudeep.holla@arm.com
Tested-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

The Arm FF for Armv8-A specification has concept of endpoints or
partitions. In the Normal world, a partition could be a VM when
the Virtualization extension is enabled or the kernel itself.

In order to handle multiple partitions, we can create a FFA device for
each such partition on a dedicated FFA bus. Similarly, different drivers
requiring FFA transport can be registered on the same bus. We can match
the device and drivers using UUID. This is mostly for the in-kernel
users with FFA drivers.

Link: https://lore.kernel.org/r/20210521151033.181846-2-sudeep.holla@arm.com
Tested-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>