dma-mapping: use unsigned long for dma_attrs
The dma-mapping core and the implementations do not change the DMA
attributes passed by pointer. Thus the pointer can point to const data.
However the attributes do not have to be a bitfield. Instead unsigned
long will do fine:
1. This is just simpler. Both in terms of reading the code and setting
attributes. Instead of initializing local attributes on the stack
and passing pointer to it to dma_set_attr(), just set the bits.
2. It brings safeness and checking for const correctness because the
attributes are passed by value.
Semantic patches for this change (at least most of them):
virtual patch
virtual context
@r@
identifier f, attrs;
@@
f(...,
- struct dma_attrs *attrs
+ unsigned long attrs
, ...)
{
...
}
@@
identifier r.f;
@@
f(...,
- NULL
+ 0
)
and
// Options: --all-includes
virtual patch
virtual context
@r@
identifier f, attrs;
type t;
@@
t f(..., struct dma_attrs *attrs);
@@
identifier r.f;
@@
f(...,
- NULL
+ 0
)
Link: http://lkml.kernel.org/r/1468399300-5399-2-git-send-email-k.kozlowski@samsung.com
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Acked-by: Vineet Gupta <vgupta@synopsys.com>
Acked-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Hans-Christian Noren Egtvedt <egtvedt@samfundet.no>
Acked-by: Mark Salter <msalter@redhat.com> [c6x]
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com> [cris]
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> [drm]
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Acked-by: Joerg Roedel <jroedel@suse.de> [iommu]
Acked-by: Fabien Dessenne <fabien.dessenne@st.com> [bdisp]
Reviewed-by: Marek Szyprowski <m.szyprowski@samsung.com> [vb2-core]
Acked-by: David Vrabel <david.vrabel@citrix.com> [xen]
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> [xen swiotlb]
Acked-by: Joerg Roedel <jroedel@suse.de> [iommu]
Acked-by: Richard Kuo <rkuo@codeaurora.org> [hexagon]
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> [m68k]
Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390]
Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Acked-by: Hans-Christian Noren Egtvedt <egtvedt@samfundet.no> [avr32]
Acked-by: Vineet Gupta <vgupta@synopsys.com> [arc]
Acked-by: Robin Murphy <robin.murphy@arm.com> [arm64 and dma-iommu]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
index 45ef3f2..1d26eeb6 100644
--- a/Documentation/DMA-API.txt
+++ b/Documentation/DMA-API.txt
@@ -369,35 +369,32 @@
dma_addr_t
dma_map_single_attrs(struct device *dev, void *cpu_addr, size_t size,
enum dma_data_direction dir,
- struct dma_attrs *attrs)
+ unsigned long attrs)
void
dma_unmap_single_attrs(struct device *dev, dma_addr_t dma_addr,
size_t size, enum dma_data_direction dir,
- struct dma_attrs *attrs)
+ unsigned long attrs)
int
dma_map_sg_attrs(struct device *dev, struct scatterlist *sgl,
int nents, enum dma_data_direction dir,
- struct dma_attrs *attrs)
+ unsigned long attrs)
void
dma_unmap_sg_attrs(struct device *dev, struct scatterlist *sgl,
int nents, enum dma_data_direction dir,
- struct dma_attrs *attrs)
+ unsigned long attrs)
The four functions above are just like the counterpart functions
without the _attrs suffixes, except that they pass an optional
-struct dma_attrs*.
-
-struct dma_attrs encapsulates a set of "DMA attributes". For the
-definition of struct dma_attrs see linux/dma-attrs.h.
+dma_attrs.
The interpretation of DMA attributes is architecture-specific, and
each attribute should be documented in Documentation/DMA-attributes.txt.
-If struct dma_attrs* is NULL, the semantics of each of these
-functions is identical to those of the corresponding function
+If dma_attrs are 0, the semantics of each of these functions
+is identical to those of the corresponding function
without the _attrs suffix. As a result dma_map_single_attrs()
can generally replace dma_map_single(), etc.
@@ -405,15 +402,15 @@
you could pass an attribute DMA_ATTR_FOO when mapping memory
for DMA:
-#include <linux/dma-attrs.h>
-/* DMA_ATTR_FOO should be defined in linux/dma-attrs.h and
+#include <linux/dma-mapping.h>
+/* DMA_ATTR_FOO should be defined in linux/dma-mapping.h and
* documented in Documentation/DMA-attributes.txt */
...
- DEFINE_DMA_ATTRS(attrs);
- dma_set_attr(DMA_ATTR_FOO, &attrs);
+ unsigned long attr;
+ attr |= DMA_ATTR_FOO;
....
- n = dma_map_sg_attrs(dev, sg, nents, DMA_TO_DEVICE, &attr);
+ n = dma_map_sg_attrs(dev, sg, nents, DMA_TO_DEVICE, attr);
....
Architectures that care about DMA_ATTR_FOO would check for its
@@ -422,12 +419,10 @@
void whizco_dma_map_sg_attrs(struct device *dev, dma_addr_t dma_addr,
size_t size, enum dma_data_direction dir,
- struct dma_attrs *attrs)
+ unsigned long attrs)
{
....
- int foo = dma_get_attr(DMA_ATTR_FOO, attrs);
- ....
- if (foo)
+ if (attrs & DMA_ATTR_FOO)
/* twizzle the frobnozzle */
....
