Commit a227fb92 authored by Marek Szyprowski's avatar Marek Szyprowski
Browse files

ARM: dma-mapping: remove offset parameter to prepare for generic dma_ops 



This patch removes the need for the offset parameter in dma bounce
functions. This is required to let dma-mapping framework on ARM
architecture to use common, generic dma_map_ops based dma-mapping
helpers.

Background and more detailed explaination:

dma_*_range_* functions are available from the early days of the dma
mapping api. They are the correct way of doing a partial syncs on the
buffer (usually used by the network device drivers). This patch changes
only the internal implementation of the dma bounce functions to let
them tunnel through dma_map_ops structure. The driver api stays
unchanged, so driver are obliged to call dma_*_range_* functions to
keep code clean and easy to understand.

The only drawback from this patch is reduced detection of the dma api
abuse. Let us consider the following code:

dma_addr = dma_map_single(dev, ptr, 64, DMA_TO_DEVICE);
dma_sync_single_range_for_cpu(dev, dma_addr+16, 0, 32, DMA_TO_DEVICE);

Without the patch such code fails, because dma bounce code is unable
to find the bounce buffer for the given dma_address. After the patch
the above sync call will be equivalent to:

dma_sync_single_range_for_cpu(dev, dma_addr, 16, 32, DMA_TO_DEVICE);

which succeeds.

I don't consider this as a real problem, because DMA API abuse should be
caught by debug_dma_* function family. This patch lets us to simplify
the internal low-level implementation without chaning the driver visible
API.

Signed-off-by: default avatarMarek Szyprowski <m.szyprowski@samsung.com>
Acked-by: default avatarKyungmin Park <kyungmin.park@samsung.com>
Tested-By: default avatarSubash Patel <subash.ramaswamy@linaro.org>
parent 553ac788

arch/arm/common/dmabounce.c

+10 −3
Original line number Diff line number Diff line
@@ -173,7 +173,8 @@ find_safe_buffer(struct dmabounce_device_info *device_info, dma_addr_t safe_dma_ 
	read_lock_irqsave(&device_info->lock, flags);



	list_for_each_entry(b, &device_info->safe_buffers, node)

		if (b->safe_dma_addr == safe_dma_addr) {

		if (b->safe_dma_addr <= safe_dma_addr &&

		    b->safe_dma_addr + b->size > safe_dma_addr) {

			rb = b;

			break;

		}
@@ -362,9 +363,10 @@ void __dma_unmap_page(struct device *dev, dma_addr_t dma_addr, size_t size, 
EXPORT_SYMBOL(__dma_unmap_page);



int dmabounce_sync_for_cpu(struct device *dev, dma_addr_t addr,

		unsigned long off, size_t sz, enum dma_data_direction dir)

		size_t sz, enum dma_data_direction dir)

{

	struct safe_buffer *buf;

	unsigned long off;



	dev_dbg(dev, "%s(dma=%#x,off=%#lx,sz=%zx,dir=%x)\n",

		__func__, addr, off, sz, dir);
@@ -373,6 +375,8 @@ int dmabounce_sync_for_cpu(struct device *dev, dma_addr_t addr, 
	if (!buf)

		return 1;



	off = addr - buf->safe_dma_addr;



	BUG_ON(buf->direction != dir);



	dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
@@ -391,9 +395,10 @@ int dmabounce_sync_for_cpu(struct device *dev, dma_addr_t addr, 
EXPORT_SYMBOL(dmabounce_sync_for_cpu);



int dmabounce_sync_for_device(struct device *dev, dma_addr_t addr,

		unsigned long off, size_t sz, enum dma_data_direction dir)

		size_t sz, enum dma_data_direction dir)

{

	struct safe_buffer *buf;

	unsigned long off;



	dev_dbg(dev, "%s(dma=%#x,off=%#lx,sz=%zx,dir=%x)\n",

		__func__, addr, off, sz, dir);
@@ -402,6 +407,8 @@ int dmabounce_sync_for_device(struct device *dev, dma_addr_t addr, 
	if (!buf)

		return 1;



	off = addr - buf->safe_dma_addr;



	BUG_ON(buf->direction != dir);



	dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",

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

+33 −34
Original line number Diff line number Diff line
@@ -266,19 +266,17 @@ extern void __dma_unmap_page(struct device *, dma_addr_t, size_t, 
/*

 * Private functions

 */

int dmabounce_sync_for_cpu(struct device *, dma_addr_t, unsigned long,

		size_t, enum dma_data_direction);

int dmabounce_sync_for_device(struct device *, dma_addr_t, unsigned long,

		size_t, enum dma_data_direction);

int dmabounce_sync_for_cpu(struct device *, dma_addr_t, size_t, enum dma_data_direction);

int dmabounce_sync_for_device(struct device *, dma_addr_t, size_t, enum dma_data_direction);

#else

static inline int dmabounce_sync_for_cpu(struct device *d, dma_addr_t addr,

	unsigned long offset, size_t size, enum dma_data_direction dir)

	size_t size, enum dma_data_direction dir)

{

	return 1;

}



static inline int dmabounce_sync_for_device(struct device *d, dma_addr_t addr,

	unsigned long offset, size_t size, enum dma_data_direction dir)

	size_t size, enum dma_data_direction dir)

{

	return 1;

}
@@ -401,6 +399,33 @@ static inline void dma_unmap_page(struct device *dev, dma_addr_t handle, 
	__dma_unmap_page(dev, handle, size, dir);

}





static inline void dma_sync_single_for_cpu(struct device *dev,

		dma_addr_t handle, size_t size, enum dma_data_direction dir)

{

	BUG_ON(!valid_dma_direction(dir));



	debug_dma_sync_single_for_cpu(dev, handle, size, dir);



	if (!dmabounce_sync_for_cpu(dev, handle, size, dir))

		return;



	__dma_single_dev_to_cpu(dma_to_virt(dev, handle), size, dir);

}



static inline void dma_sync_single_for_device(struct device *dev,

		dma_addr_t handle, size_t size, enum dma_data_direction dir)

{

	BUG_ON(!valid_dma_direction(dir));



	debug_dma_sync_single_for_device(dev, handle, size, dir);



	if (!dmabounce_sync_for_device(dev, handle, size, dir))

		return;



	__dma_single_cpu_to_dev(dma_to_virt(dev, handle), size, dir);

}



/**

 * dma_sync_single_range_for_cpu

 * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
@@ -423,40 +448,14 @@ static inline void dma_sync_single_range_for_cpu(struct device *dev, 
		dma_addr_t handle, unsigned long offset, size_t size,

		enum dma_data_direction dir)

{

	BUG_ON(!valid_dma_direction(dir));



	debug_dma_sync_single_for_cpu(dev, handle + offset, size, dir);



	if (!dmabounce_sync_for_cpu(dev, handle, offset, size, dir))

		return;



	__dma_single_dev_to_cpu(dma_to_virt(dev, handle) + offset, size, dir);

	dma_sync_single_for_cpu(dev, handle + offset, size, dir);

}



static inline void dma_sync_single_range_for_device(struct device *dev,

		dma_addr_t handle, unsigned long offset, size_t size,

		enum dma_data_direction dir)

{

	BUG_ON(!valid_dma_direction(dir));



	debug_dma_sync_single_for_device(dev, handle + offset, size, dir);



	if (!dmabounce_sync_for_device(dev, handle, offset, size, dir))

		return;



	__dma_single_cpu_to_dev(dma_to_virt(dev, handle) + offset, size, dir);

}



static inline void dma_sync_single_for_cpu(struct device *dev,

		dma_addr_t handle, size_t size, enum dma_data_direction dir)

{

	dma_sync_single_range_for_cpu(dev, handle, 0, size, dir);

}



static inline void dma_sync_single_for_device(struct device *dev,

		dma_addr_t handle, size_t size, enum dma_data_direction dir)

{

	dma_sync_single_range_for_device(dev, handle, 0, size, dir);

	dma_sync_single_for_device(dev, handle + offset, size, dir);

}



/*

arch/arm/mm/dma-mapping.c

+2 −2
Original line number Diff line number Diff line
@@ -660,7 +660,7 @@ void dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg, 
	int i;



	for_each_sg(sg, s, nents, i) {

		if (!dmabounce_sync_for_cpu(dev, sg_dma_address(s), 0,

		if (!dmabounce_sync_for_cpu(dev, sg_dma_address(s),

					    sg_dma_len(s), dir))

			continue;
@@ -686,7 +686,7 @@ void dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, 
	int i;



	for_each_sg(sg, s, nents, i) {

		if (!dmabounce_sync_for_device(dev, sg_dma_address(s), 0,

		if (!dmabounce_sync_for_device(dev, sg_dma_address(s),

					sg_dma_len(s), dir))

			continue;

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