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The sysFS and Perf access methods can't be allowed to interfere
with one another.  As such introducing guards to access
functions that prevents moving forward if a TMC is already
being used.
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>