pmu: add adb_autopoll_block() and adb_autopoll_unblock() functions

Ensure that the PMU buffer is protected from autopoll requests overwriting
its contents whilst existing PMU requests are in progress.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Tested-by: Finn Thain <fthain@telegraphics.com.au>
Acked-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20200623204936.24064-18-mark.cave-ayland@ilande.co.uk>
1 file changed