iommu/arm-smmu: lock clock enabling and reference counting

Ensure that clock enabling and reference counting is done atomically
to avoid any potential race conditions.

An example of a potential race condition is that while thread one is
enabling the clocks thread two could enter and then exit the clock
enabling function early because of reference counting. This could
lead to thread two attempting to access registers before the clocks
are enabled.

Have removed the regulator reference because enabling the regulators
involves the use of a mutex so spin locks cannot be used to protect
the reference count. Also the use of a regulator reference count is
of limited benefit since there is only one regulator to enable.

Change-Id: I7215bbf9157907fde24c94841e347370769423c8
Signed-off-by: Liam Mark <lmark@codeaurora.org>

0 files changed, 0 insertions, 0 deletions