Add support for cyclic DMA's periodic callbacks. Drivers are expected
to call vchan_cyclic_callback() when a period has completed, which will
schedule the tasklet to make the callback into the driver.
As callbacks are made from tasklet context, it is important to realise
that we don't guarantee a callback for each completed period, but for
N completed periods where N may be greater than one.
Tested-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Add a function to find a descriptor within the depths of the
virtualized DMA channel support. Needed for tx_status functionality.
Tested-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Split the virtual slave channel DMA support from the sa11x0 driver so
this code can be shared with other slave DMA engine drivers.
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
