linux.git/include/linux/dma-direct.h, branch v5.7-rc2

dma-mapping: treat dev->bus_dma_mask as a DMA limit

2019-11-21T17:14:35+00:00

Using a mask to represent bus DMA constraints has a set of limitations.
The biggest one being it can only hold a power of two (minus one). The
DMA mapping code is already aware of this and treats dev->bus_dma_mask
as a limit. This quirk is already used by some architectures although
still rare.

With the introduction of the Raspberry Pi 4 we've found a new contender
for the use of bus DMA limits, as its PCIe bus can only address the
lower 3GB of memory (of a total of 4GB). This is impossible to represent
with a mask. To make things worse the device-tree code rounds non power
of two bus DMA limits to the next power of two, which is unacceptable in
this case.

In the light of this, rename dev->bus_dma_mask to dev->bus_dma_limit all
over the tree and treat it as such. Note that dev->bus_dma_limit should
contain the higher accessible DMA address.

Signed-off-by: Nicolas Saenz Julienne 
Reviewed-by: Robin Murphy 
Signed-off-by: Christoph Hellwig

Merge branch 'for-next/zone-dma' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux into dma-mapping-for-next

2019-11-21T17:13:03+00:00

Pull in a stable branch from the arm64 tree that adds the zone_dma_bits
variable to avoid creating hard to resolve conflicts with that addition.

dma-direct: exclude dma_direct_map_resource from the min_low_pfn check

2019-11-20T19:31:41+00:00

The valid memory address check in dma_capable only makes sense when mapping
normal memory, not when using dma_map_resource to map a device resource.
Add a new boolean argument to dma_capable to exclude that check for the
dma_map_resource case.

Fixes: b12d66278dd6 ("dma-direct: check for overflows on 32 bit DMA addresses")
Reported-by: Marek Szyprowski 
Signed-off-by: Christoph Hellwig 
Acked-by: Marek Szyprowski 
Tested-by: Marek Szyprowski

dma-direct: avoid a forward declaration for phys_to_dma

2019-11-20T19:31:40+00:00

Move dma_capable down a bit so that we don't need a forward declaration
for phys_to_dma.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Nicolas Saenz Julienne

dma-direct: unify the dma_capable definitions

2019-11-20T19:31:40+00:00

Currently each architectures that wants to override dma_to_phys and
phys_to_dma also has to provide dma_capable.  But there isn't really
any good reason for that.  powerpc and mips just have copies of the
generic one minus the latests fix, and the arm one was the inspiration
for said fix, but misses the bus_dma_mask handling.
Make all architectures use the generic version instead.

Signed-off-by: Christoph Hellwig 
Acked-by: Michael Ellerman  (powerpc)
Reviewed-by: Nicolas Saenz Julienne

dma-direct: check for overflows on 32 bit DMA addresses

2019-11-11T09:52:18+00:00

As seen on the new Raspberry Pi 4 and sta2x11's DMA implementation it is
possible for a device configured with 32 bit DMA addresses and a partial
DMA mapping located at the end of the address space to overflow. It
happens when a higher physical address, not DMAable, is translated to
it's DMA counterpart.

For example the Raspberry Pi 4, configurable up to 4 GB of memory, has
an interconnect capable of addressing the lower 1 GB of physical memory
with a DMA offset of 0xc0000000. It transpires that, any attempt to
translate physical addresses higher than the first GB will result in an
overflow which dma_capable() can't detect as it only checks for
addresses bigger then the maximum allowed DMA address.

Fix this by verifying in dma_capable() if the DMA address range provided
is at any point lower than the minimum possible DMA address on the bus.

Signed-off-by: Nicolas Saenz Julienne 
Signed-off-by: Christoph Hellwig

dma-direct: provide mmap and get_sgtable method overrides

2019-11-11T09:52:15+00:00

For dma-direct we know that the DMA address is an encoding of the
physical address that we can trivially decode.  Use that fact to
provide implementations that do not need the arch_dma_coherent_to_pfn
architecture hook.  Note that we still can only support mmap of
non-coherent memory only if the architecture provides a way to set an
uncached bit in the page tables.  This must be true for architectures
that use the generic remap helpers, but other architectures can also
manually select it.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Max Filippov

dma-direct: remove the dma_handle argument to __dma_direct_alloc_pages

2019-11-07T16:25:57+00:00

The argument isn't used anywhere, so stop passing it.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Max Filippov

dma-direct: remove __dma_direct_free_pages

2019-11-07T16:25:40+00:00

We can just call dma_free_contiguous directly instead of wrapping it.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Max Filippov

dma/direct: turn ARCH_ZONE_DMA_BITS into a variable

2019-11-01T09:41:18+00:00

Some architectures, notably ARM, are interested in tweaking this
depending on their runtime DMA addressing limitations.

Acked-by: Christoph Hellwig 
Signed-off-by: Nicolas Saenz Julienne 
Signed-off-by: Catalin Marinas