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efa70f2fdc
This API is the equivalent of alloc_pages, except that the returned memory is guaranteed to be DMA addressable by the passed in device. The implementation will also be used to provide a more sensible replacement for DMA_ATTR_NON_CONSISTENT flag. Additionally dma_alloc_noncoherent is switched over to use dma_alloc_pages as its backend. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de> (MIPS part)
62 lines
1.5 KiB
C
62 lines
1.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* DMA operations that map to virtual addresses without flushing memory.
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*/
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#include <linux/export.h>
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#include <linux/mm.h>
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#include <linux/dma-mapping.h>
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#include <linux/scatterlist.h>
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static void *dma_virt_alloc(struct device *dev, size_t size,
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dma_addr_t *dma_handle, gfp_t gfp,
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unsigned long attrs)
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{
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void *ret;
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ret = (void *)__get_free_pages(gfp | __GFP_ZERO, get_order(size));
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if (ret)
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*dma_handle = (uintptr_t)ret;
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return ret;
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}
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static void dma_virt_free(struct device *dev, size_t size,
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void *cpu_addr, dma_addr_t dma_addr,
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unsigned long attrs)
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{
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free_pages((unsigned long)cpu_addr, get_order(size));
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}
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static dma_addr_t dma_virt_map_page(struct device *dev, struct page *page,
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unsigned long offset, size_t size,
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enum dma_data_direction dir,
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unsigned long attrs)
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{
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return (uintptr_t)(page_address(page) + offset);
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}
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static int dma_virt_map_sg(struct device *dev, struct scatterlist *sgl,
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int nents, enum dma_data_direction dir,
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unsigned long attrs)
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{
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int i;
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struct scatterlist *sg;
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for_each_sg(sgl, sg, nents, i) {
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BUG_ON(!sg_page(sg));
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sg_dma_address(sg) = (uintptr_t)sg_virt(sg);
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sg_dma_len(sg) = sg->length;
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}
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return nents;
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}
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const struct dma_map_ops dma_virt_ops = {
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.alloc = dma_virt_alloc,
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.free = dma_virt_free,
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.map_page = dma_virt_map_page,
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.map_sg = dma_virt_map_sg,
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.alloc_pages = dma_common_alloc_pages,
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.free_pages = dma_common_free_pages,
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};
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EXPORT_SYMBOL(dma_virt_ops);
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