RFC Genericise the IOVA allocator

Hi all,

I've been implementing IOMMU DMA mapping for arm64, based on tidied-up parts of the existing arch/arm/mm/dma-mapping.c with a clear divide between the arch-specific parts and the general DMA-API to IOMMU-API layer so that that can be shared; similar to what Ritesh started before and was unable to complete[1], but working in the other direction.

The first part of that tidy-up involved ripping out the homebrewed IOVA allocator and plumbing in iova.c, necessitating the changes presented here. The rest is currently sat under arch/arm64 for the sake of getting it working quickly with minimal impact - ideally I'd move it out and port arch/arm before merging, but I don't know quite how impatient people are. Regardless of that decision, this bit stands alone, so here it is.

Feel free to ignore patches 1 and 2, since I see Sakari has recently posted a more thorough series for that[2], that frankly looks nicer ;) I've merely left them in as context here.

[1]:http://thread.gmane.org/gmane.linux.ports.arm.kernel/331299 [2]:http://article.gmane.org/gmane.linux.kernel.iommu/7436

Robin Murphy (4):
iommu: build iova.c for any IOMMU
iommu: consolidate IOVA allocator code
iommu: make IOVA domain low limit flexible
iommu: make IOVA domain page size explicit