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https://github.com/torvalds/linux
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a8463d4b0e
We are going to require dma_ops for several common drivers, even for systems that do have an identity mapping. Lets provide some minimal no-op dma_ops that can be used for that purpose. Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Reviewed-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
75 lines
1.7 KiB
C
75 lines
1.7 KiB
C
/*
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* lib/dma-noop.c
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*
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* Simple DMA noop-ops that map 1:1 with 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_noop_alloc(struct device *dev, size_t size,
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dma_addr_t *dma_handle, gfp_t gfp,
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struct dma_attrs *attrs)
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{
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void *ret;
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ret = (void *)__get_free_pages(gfp, get_order(size));
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if (ret)
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*dma_handle = virt_to_phys(ret);
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return ret;
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}
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static void dma_noop_free(struct device *dev, size_t size,
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void *cpu_addr, dma_addr_t dma_addr,
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struct dma_attrs *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_noop_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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struct dma_attrs *attrs)
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{
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return page_to_phys(page) + offset;
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}
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static int dma_noop_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
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enum dma_data_direction dir, struct dma_attrs *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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void *va;
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BUG_ON(!sg_page(sg));
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va = sg_virt(sg);
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sg_dma_address(sg) = (dma_addr_t)virt_to_phys(va);
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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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static int dma_noop_mapping_error(struct device *dev, dma_addr_t dma_addr)
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{
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return 0;
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}
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static int dma_noop_supported(struct device *dev, u64 mask)
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{
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return 1;
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}
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struct dma_map_ops dma_noop_ops = {
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.alloc = dma_noop_alloc,
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.free = dma_noop_free,
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.map_page = dma_noop_map_page,
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.map_sg = dma_noop_map_sg,
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.mapping_error = dma_noop_mapping_error,
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.dma_supported = dma_noop_supported,
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};
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EXPORT_SYMBOL(dma_noop_ops);
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