Damien George 0c0807e084 stm32/dma: Add functions for external users of DMA to enable clock.
Any external user of DMA (eg a board with a custom DMA driver) must call
dma_external_acquire() for their DMA controller/stream to ensure that the
DMA clock is not automatically turned off while it's still being used
externally.

Signed-off-by: Damien George <damien@micropython.org>
2021-09-16 13:01:43 +10:00
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