1 files changed, 31 insertions, 0 deletions

diff --git a/drivers/base/dma-mapping.c b/drivers/base/dma-mapping.c
index 6f3676f1559f..db5db02e885f 100644
--- a/drivers/base/dma-mapping.c
+++ b/drivers/base/dma-mapping.c
@@ -10,6 +10,7 @@
 #include <linux/dma-mapping.h>
 #include <linux/export.h>
 #include <linux/gfp.h>
+#include <asm-generic/dma-coherent.h>
 
 /*
  * Managed DMA API
@@ -218,3 +219,33 @@ void dmam_release_declared_memory(struct device *dev)
 EXPORT_SYMBOL(dmam_release_declared_memory);
 
 #endif
+
+/*
+ * 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)
+{
+        int ret = -ENXIO;
+#ifdef CONFIG_MMU
+        unsigned long user_count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
+        unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
+        unsigned long pfn = page_to_pfn(virt_to_page(cpu_addr));
+        unsigned long off = vma->vm_pgoff;
+
+        vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+
+        if (dma_mmap_from_coherent(dev, vma, cpu_addr, size, &ret))
+                return ret;
+
+        if (off < count && user_count <= (count - off)) {
+                ret = remap_pfn_range(vma, vma->vm_start,
+                                      pfn + off,
+                                      user_count << PAGE_SHIFT,
+                                      vma->vm_page_prot);
+        }
+#endif  /* CONFIG_MMU */
+
+        return ret;
+}
+EXPORT_SYMBOL(dma_common_mmap);