提交 56f55f8b 编写于 作者: R Russell King 提交者: Russell King

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

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: NRussell King <rmk+kernel@arm.linux.org.uk>
上级 afd1a321
......@@ -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
......
......@@ -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
......
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