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[ARM] dma: provide a better dma_map_page() implementation

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We can translate a struct page directly to a DMA address using
page_to_dma().  No need to use page_address() followed by
virt_to_dma().

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Russell King 2008-09-25 20:59:12 +01:00 committed by Russell King
parent afd1a321c4
commit 56f55f8b58
2 changed files with 23 additions and 1 deletions
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13
arch/arm/common/dmabounce.c
View File

@ -412,6 +412,19 @@ dma_map_single(struct device *dev, void *ptr, size_t size,
return dma_addr;
}
dma_addr_t dma_map_page(struct device *dev, struct page *page,
unsigned long offset, size_t size,
enum dma_data_direction dir)
{
dev_dbg(dev, "%s(page=%p,off=%#lx,size=%zx,dir=%x)\n",
__func__, page, offset, size, dir);
BUG_ON(dir == DMA_NONE);
return map_single(dev, page_address(page) + offset, size, dir);
}
EXPORT_SYMBOL(dma_map_page);
/*
* see if a mapped address was really a "safe" buffer and if so, copy
* the data from the safe buffer back to the unsafe buffer and free up

11
arch/arm/include/asm/dma-mapping.h
View File

@ -227,13 +227,22 @@ extern dma_addr_t dma_map_single(struct device *,void *, size_t, enum dma_data_d
* can regain ownership by calling dma_unmap_page() or
* dma_sync_single_for_cpu().
*/
#ifndef CONFIG_DMABOUNCE
static inline dma_addr_t
dma_map_page(struct device *dev, struct page *page,
unsigned long offset, size_t size,
enum dma_data_direction dir)
{
return dma_map_single(dev, page_address(page) + offset, size, dir);
if (!arch_is_coherent())
dma_cache_maint(page_address(page) + offset, size, dir);
return page_to_dma(dev, page) + offset;
}
#else
extern dma_addr_t dma_map_page(struct device *dev, struct page *page,
unsigned long offset, size_t size,
enum dma_data_direction dir);
#endif
/**
* dma_unmap_single - unmap a single buffer previously mapped