From 00085f1efa387a8ce100e3734920f7639c80caa3 Mon Sep 17 00:00:00 2001 From: Krzysztof Kozlowski Date: Wed, 3 Aug 2016 13:46:00 -0700 Subject: 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 Acked-by: Vineet Gupta Acked-by: Robin Murphy Acked-by: Hans-Christian Noren Egtvedt Acked-by: Mark Salter [c6x] Acked-by: Jesper Nilsson [cris] Acked-by: Daniel Vetter [drm] Reviewed-by: Bart Van Assche Acked-by: Joerg Roedel [iommu] Acked-by: Fabien Dessenne [bdisp] Reviewed-by: Marek Szyprowski [vb2-core] Acked-by: David Vrabel [xen] Acked-by: Konrad Rzeszutek Wilk [xen swiotlb] Acked-by: Joerg Roedel [iommu] Acked-by: Richard Kuo [hexagon] Acked-by: Geert Uytterhoeven [m68k] Acked-by: Gerald Schaefer [s390] Acked-by: Bjorn Andersson Acked-by: Hans-Christian Noren Egtvedt [avr32] Acked-by: Vineet Gupta [arc] Acked-by: Robin Murphy [arm64 and dma-iommu] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/DMA-API.txt | 33 ++++++++++++++------------------- 1 file changed, 14 insertions(+), 19 deletions(-) (limited to 'Documentation/DMA-API.txt') diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt index 45ef3f279c3b..1d26eeb6b5f6 100644 --- a/Documentation/DMA-API.txt +++ b/Documentation/DMA-API.txt @@ -369,35 +369,32 @@ See also dma_map_single(). 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 @@ As an example of the use of the *_attrs functions, here's how you could pass an attribute DMA_ATTR_FOO when mapping memory for DMA: -#include -/* DMA_ATTR_FOO should be defined in linux/dma-attrs.h and +#include +/* 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 @@ routines, e.g.: 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 */ .... -- cgit v1.2.3