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authorChristoph Hellwig <hch@lst.de>2020-08-18 10:30:44 +0300
committerChristoph Hellwig <hch@lst.de>2020-09-11 10:14:56 +0300
commit545d29272f38ba4791cca2a5a86fe6766f462f18 (patch)
tree3977606168e9b428a34072b39d14a98d38a9777b /kernel/dma/ops_helpers.c
parent5ceda74093a5c1c3f42a02b894df031f3bbc9af1 (diff)
downloadlinux-545d29272f38ba4791cca2a5a86fe6766f462f18.tar.xz
dma-mapping: move dma_common_{mmap,get_sgtable} out of mapping.c
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>
Diffstat (limited to 'kernel/dma/ops_helpers.c')
-rw-r--r--kernel/dma/ops_helpers.c51
1 files changed, 51 insertions, 0 deletions
diff --git a/kernel/dma/ops_helpers.c b/kernel/dma/ops_helpers.c
new file mode 100644
index 000000000000..e443c69be429
--- /dev/null
+++ b/kernel/dma/ops_helpers.c
@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Helpers for DMA ops implementations. These generally rely on the fact that
+ * the allocated memory contains normal pages in the direct kernel mapping.
+ */
+#include <linux/dma-noncoherent.h>
+
+/*
+ * Create scatter-list for the already allocated DMA buffer.
+ */
+int dma_common_get_sgtable(struct device *dev, struct sg_table *sgt,
+ void *cpu_addr, dma_addr_t dma_addr, size_t size,
+ unsigned long attrs)
+{
+ struct page *page = virt_to_page(cpu_addr);
+ int ret;
+
+ ret = sg_alloc_table(sgt, 1, GFP_KERNEL);
+ if (!ret)
+ sg_set_page(sgt->sgl, page, PAGE_ALIGN(size), 0);
+ return ret;
+}
+
+/*
+ * Create userspace mapping for the DMA-coherent memory.
+ */
+int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
+ void *cpu_addr, dma_addr_t dma_addr, size_t size,
+ unsigned long attrs)
+{
+#ifdef CONFIG_MMU
+ unsigned long user_count = vma_pages(vma);
+ unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
+ unsigned long off = vma->vm_pgoff;
+ int ret = -ENXIO;
+
+ vma->vm_page_prot = dma_pgprot(dev, vma->vm_page_prot, attrs);
+
+ if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))
+ return ret;
+
+ if (off >= count || user_count > count - off)
+ return -ENXIO;
+
+ return remap_pfn_range(vma, vma->vm_start,
+ page_to_pfn(virt_to_page(cpu_addr)) + vma->vm_pgoff,
+ user_count << PAGE_SHIFT, vma->vm_page_prot);
+#else
+ return -ENXIO;
+#endif /* CONFIG_MMU */
+}