arc dma mapping cleanups/fixes and generic noncohernt dma code

[Alexey.Brodkin@synopsys.com (Alexey Brodkin)]

Hi Christoph,

On Fri, 2018-05-18@15:45 +0200, Christoph Hellwig wrote:
> Hi all,
> 
> this series continues consolidating the dma-mapping code, with a focus
> on architectures that do not (always) provide cache coherence for DMA.
> Three architectures (arm, mips and powerpc) are still left to be
> converted later due to complexity of their dma ops selection.
> 
> The dma-noncoherent ops calls the dma-direct ops for the actual
> translation of streaming mappins and allow the architecture to provide
> any cache flushing required for cpu to device and/or device to cpu
> ownership transfers.  The dma coherent allocator is for now still left
> entirely to architecture supplied implementations due the amount of
> variations.  Hopefully we can do some consolidation for them later on
> as well.
> 
> Because this series sits on top of two previously submitted series
> a git tree might be useful to actually test it.  It is provided here:
> 
>     git://git.infradead.org/users/hch/misc.git arc-dma
> 
> Gitweb:
> 
>     https://urldefense.proofpoint.com/v2/url?u=http-3A__git.infradead.org_users_hch_misc.git_shortlog_refs_heads_arc-2Ddma&d=DwIBAg&c=DPL6_X_6JkXFx7
> AXWqB0tg&r=lqdeeSSEes0GFDDl656eViXO7breS55ytWkhpk5R81I&m=QNC0zOG4bRotSxdjQfFXl0dAQJCtnxtF9435wAuJlu0&s=Wad1ptsFpknoSn0ebr3_QMJn9G_D3eIS-LYMwGfOJ-
> I&e=
> 
> Changes since previous bigger series:
>  - take the offset into account in noncoherent_dma_map_page (Alexey Brodkin)
>  - fix dma directions in arc (Alexey Brodkin)
>  - split arc changes into smaller patches

I really like this series especially how it trimmed down arch/arc/mm/dma.c:
---------------------------->8----------------------------
git diff --stat HEAD~4
 arch/arc/Kconfig                   |   4 +++
 arch/arc/include/asm/Kbuild        |   1 +
 arch/arc/include/asm/dma-mapping.h |  21 ---------------
 arch/arc/mm/cache.c                |   2 +-
 arch/arc/mm/dma.c                  | 162 ++++++++++------------------------------------------------------------------------------------------------
---------
---------------------------->8----------------------------

So if we set aside my complaints about direction in arch_sync_dma_for_{device|cpu}()...

Tested-by: Alexey Brodkin <abrodkin at synopsys.com>

Let's still wait for Vineet's ack as he's the chief maintainer for ARC :)

-Alexey