firmware: arm_scmi: Fix chan_free cleanup on SMC

[ Upstream commit d1ff11d7 ]

SCMI transport based on SMC can optionally use an additional IRQ to
signal message completion. The associated interrupt handler is currently
allocated using devres but on shutdown the core SCMI stack will call
.chan_free() well before any managed cleanup is invoked by devres.
As a consequence, the arrival of a late reply to an in-flight pending
transaction could still trigger the interrupt handler well after the
SCMI core has cleaned up the channels, with unpleasant results.

Inhibit further message processing on the IRQ path by explicitly freeing
the IRQ inside .chan_free() callback itself.

Fixes: dd820ee2

 ("firmware: arm_scmi: Augment SMC/HVC to allow optional interrupt")
Reported-by: Bjorn Andersson <andersson@kernel.org>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20230719173533.2739319-1-cristian.marussi@arm.com


Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>