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Commit 00085f1e authored by Krzysztof Kozlowski's avatar Krzysztof Kozlowski Committed by Linus Torvalds
Browse files

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: default avatarKrzysztof Kozlowski <k.kozlowski@samsung.com>
Acked-by: default avatarVineet Gupta <vgupta@synopsys.com>
Acked-by: default avatarRobin Murphy <robin.murphy@arm.com>
Acked-by: default avatarHans-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: default avatarBart 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: default avatarBjorn 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1605d271

Documentation/DMA-API.txt

+14 −19
Original line number Diff line number Diff line
@@ -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 <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 @@ 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 */

	....

Documentation/DMA-attributes.txt

+1 −1
Original line number Diff line number Diff line
@@ -2,7 +2,7 @@ 
			==============



This document describes the semantics of the DMA attributes that are

defined in linux/dma-attrs.h.

defined in linux/dma-mapping.h.



DMA_ATTR_WRITE_BARRIER

----------------------

arch/alpha/include/asm/dma-mapping.h

+0 −2
Original line number Diff line number Diff line 
#ifndef _ALPHA_DMA_MAPPING_H

#define _ALPHA_DMA_MAPPING_H



#include <linux/dma-attrs.h>



extern struct dma_map_ops *dma_ops;



static inline struct dma_map_ops *get_dma_ops(struct device *dev)

arch/alpha/kernel/pci-noop.c

+1 −1
Original line number Diff line number Diff line
@@ -109,7 +109,7 @@ sys_pciconfig_write(unsigned long bus, unsigned long dfn, 


static void *alpha_noop_alloc_coherent(struct device *dev, size_t size,

				       dma_addr_t *dma_handle, gfp_t gfp,

				       struct dma_attrs *attrs)

				       unsigned long attrs)

{

	void *ret;

arch/alpha/kernel/pci_iommu.c

+6 −6
Original line number Diff line number Diff line
@@ -349,7 +349,7 @@ static struct pci_dev *alpha_gendev_to_pci(struct device *dev) 
static dma_addr_t alpha_pci_map_page(struct device *dev, struct page *page,

				     unsigned long offset, size_t size,

				     enum dma_data_direction dir,

				     struct dma_attrs *attrs)

				     unsigned long attrs)

{

	struct pci_dev *pdev = alpha_gendev_to_pci(dev);

	int dac_allowed;
@@ -369,7 +369,7 @@ static dma_addr_t alpha_pci_map_page(struct device *dev, struct page *page, 


static void alpha_pci_unmap_page(struct device *dev, dma_addr_t dma_addr,

				 size_t size, enum dma_data_direction dir,

				 struct dma_attrs *attrs)

				 unsigned long attrs)

{

	unsigned long flags;

	struct pci_dev *pdev = alpha_gendev_to_pci(dev);
@@ -433,7 +433,7 @@ static void alpha_pci_unmap_page(struct device *dev, dma_addr_t dma_addr, 


static void *alpha_pci_alloc_coherent(struct device *dev, size_t size,

				      dma_addr_t *dma_addrp, gfp_t gfp,

				      struct dma_attrs *attrs)

				      unsigned long attrs)

{

	struct pci_dev *pdev = alpha_gendev_to_pci(dev);

	void *cpu_addr;
@@ -478,7 +478,7 @@ static void *alpha_pci_alloc_coherent(struct device *dev, size_t size, 


static void alpha_pci_free_coherent(struct device *dev, size_t size,

				    void *cpu_addr, dma_addr_t dma_addr,

				    struct dma_attrs *attrs)

				    unsigned long attrs)

{

	struct pci_dev *pdev = alpha_gendev_to_pci(dev);

	pci_unmap_single(pdev, dma_addr, size, PCI_DMA_BIDIRECTIONAL);
@@ -651,7 +651,7 @@ sg_fill(struct device *dev, struct scatterlist *leader, struct scatterlist *end, 


static int alpha_pci_map_sg(struct device *dev, struct scatterlist *sg,

			    int nents, enum dma_data_direction dir,

			    struct dma_attrs *attrs)

			    unsigned long attrs)

{

	struct pci_dev *pdev = alpha_gendev_to_pci(dev);

	struct scatterlist *start, *end, *out;
@@ -729,7 +729,7 @@ static int alpha_pci_map_sg(struct device *dev, struct scatterlist *sg, 


static void alpha_pci_unmap_sg(struct device *dev, struct scatterlist *sg,

			       int nents, enum dma_data_direction dir,

			       struct dma_attrs *attrs)

			       unsigned long attrs)

{

	struct pci_dev *pdev = alpha_gendev_to_pci(dev);

	unsigned long flags;