The x86 busdma subsystem allows using multiple implementations.
By default the classic bounce buffer approach is used, however
on systems with IOMMU it could be in runtime switched to more
efficient hardware accelerated implementation.
This commit adds ARM64 port of the x86 busdma framework and bounce
buffer backend. It is ready to use on IO coherent systems. If the
IO coherency cannot be guaranteed, the cache management operations have
to be added to this code in places marked by /* XXX ARM64TODO (...) */
comments. Also IOMMU support might be added by registering another
busdma implementation like it is already done on the x86.
Reviewed by: andrew, emaste
Obtained from: Semihalf
Sponsored by: The FreeBSD Foundation
This is only the minimum set of files needed to boot in qemu. As such it is
missing a few things.
The bus_dma code is currently only stub functions with a full implementation
from the development tree to follow.
The gic driver has been copied as the interrupt framework is different. It
is expected the two drivers will be merged by the arm intrng project,
however this will need to be imported into the tree and support for arm64
would need to be added.
This includes code developed by myself, SemiHalf, Ed Maste, and Robin
Randhawa from ARM. This has been funded by the FreeBSD Foundation, with
early development by myself in my spare time with assistance from Robin.
Differential Revision: https://reviews.freebsd.org/D2199
Reviewed by: emaste, imp
Relnotes: yes
Sponsored by: The FreeBSD Foundation
