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2012-03-07DMA: sa11x0: add SA-11x0 DMA driverRussell King1-0/+24
Add support for the SA-11x0 DMA driver, which replaces the private API version in arch/arm/mach-sa1100/dma.c. We model this as a set of virtual DMA channels, one for each request signal, and assign the virtual DMA channel to a physical DMA channel when there is work to be done. This allows DMA users to claim their channels, and hold them while not in use, without affecting the availability of the physical channels. Another advantage over this approach, compared to the private version, is that a channel can be reconfigured on the fly without having to release and re-request it - which for the IrDA driver, allows us to use DMA for SIR mode transmit without eating up three physical channels. As IrDA is half-duplex, we actually only need one physical channel, and this architecture allows us to achieve that. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>