forked from luck/tmp_suning_uos_patched
545d29272f
Add a new file that contains helpers for misc DMA ops, which is only built when CONFIG_DMA_OPS is set. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Robin Murphy <robin.murphy@arm.com>
52 lines
1.4 KiB
C
52 lines
1.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Helpers for DMA ops implementations. These generally rely on the fact that
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* the allocated memory contains normal pages in the direct kernel mapping.
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*/
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#include <linux/dma-noncoherent.h>
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/*
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* Create scatter-list for the already allocated DMA buffer.
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*/
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int dma_common_get_sgtable(struct device *dev, struct sg_table *sgt,
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void *cpu_addr, dma_addr_t dma_addr, size_t size,
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unsigned long attrs)
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{
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struct page *page = virt_to_page(cpu_addr);
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int ret;
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ret = sg_alloc_table(sgt, 1, GFP_KERNEL);
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if (!ret)
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sg_set_page(sgt->sgl, page, PAGE_ALIGN(size), 0);
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return ret;
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}
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/*
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* Create userspace mapping for the DMA-coherent memory.
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*/
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int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
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void *cpu_addr, dma_addr_t dma_addr, size_t size,
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unsigned long attrs)
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{
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#ifdef CONFIG_MMU
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unsigned long user_count = vma_pages(vma);
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unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
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unsigned long off = vma->vm_pgoff;
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int ret = -ENXIO;
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vma->vm_page_prot = dma_pgprot(dev, vma->vm_page_prot, attrs);
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if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))
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return ret;
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if (off >= count || user_count > count - off)
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return -ENXIO;
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return remap_pfn_range(vma, vma->vm_start,
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page_to_pfn(virt_to_page(cpu_addr)) + vma->vm_pgoff,
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user_count << PAGE_SHIFT, vma->vm_page_prot);
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#else
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return -ENXIO;
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#endif /* CONFIG_MMU */
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}
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