1 files changed, 45 insertions, 2 deletions

diff --git a/drivers/base/dma-coherent.c b/drivers/base/dma-coherent.c
index f369e279598..7d6e84a5142 100644
--- a/drivers/base/dma-coherent.c
+++ b/drivers/base/dma-coherent.c
@@ -4,17 +4,19 @@
  */
 #include <linux/slab.h>
 #include <linux/kernel.h>
+#include <linux/module.h>
 #include <linux/dma-mapping.h>
 
 struct dma_coherent_mem {
 	void		*virt_base;
 	dma_addr_t	device_base;
+	unsigned long	pfn_base;
 	int		size;
 	int		flags;
 	unsigned long	*bitmap;
 };
 
-int dma_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr,
+int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
 				dma_addr_t device_addr, size_t size, int flags)
 {
 	void __iomem *mem_base = NULL;
@@ -30,7 +32,7 @@ int dma_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr,
 
 	/* FIXME: this routine just ignores DMA_MEMORY_INCLUDES_CHILDREN */
 
-	mem_base = ioremap(bus_addr, size);
+	mem_base = ioremap(phys_addr, size);
 	if (!mem_base)
 		goto out;
 
@@ -43,6 +45,7 @@ int dma_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr,
 
 	dev->dma_mem->virt_base = mem_base;
 	dev->dma_mem->device_base = device_addr;
+	dev->dma_mem->pfn_base = PFN_DOWN(phys_addr);
 	dev->dma_mem->size = pages;
 	dev->dma_mem->flags = flags;
 
@@ -175,3 +178,43 @@ int dma_release_from_coherent(struct device *dev, int order, void *vaddr)
 	return 0;
 }
 EXPORT_SYMBOL(dma_release_from_coherent);
+
+/**
+ * dma_mmap_from_coherent() - try to mmap the memory allocated from
+ * per-device coherent memory pool to userspace
+ * @dev:	device from which the memory was allocated
+ * @vma:	vm_area for the userspace memory
+ * @vaddr:	cpu address returned by dma_alloc_from_coherent
+ * @size:	size of the memory buffer allocated by dma_alloc_from_coherent
+ * @ret:	result from remap_pfn_range()
+ *
+ * This checks whether the memory was allocated from the per-device
+ * coherent memory pool and if so, maps that memory to the provided vma.
+ *
+ * Returns 1 if we correctly mapped the memory, or 0 if the caller should
+ * proceed with mapping memory from generic pools.
+ */
+int dma_mmap_from_coherent(struct device *dev, struct vm_area_struct *vma,
+			   void *vaddr, size_t size, int *ret)
+{
+	struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
+
+	if (mem && vaddr >= mem->virt_base && vaddr + size <=
+		   (mem->virt_base + (mem->size << PAGE_SHIFT))) {
+		unsigned long off = vma->vm_pgoff;
+		int start = (vaddr - mem->virt_base) >> PAGE_SHIFT;
+		int user_count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
+		int count = size >> PAGE_SHIFT;
+
+		*ret = -ENXIO;
+		if (off < count && user_count <= count - off) {
+			unsigned long pfn = mem->pfn_base + start + off;
+			*ret = remap_pfn_range(vma, vma->vm_start, pfn,
+					       user_count << PAGE_SHIFT,
+					       vma->vm_page_prot);
+		}
+		return 1;
+	}
+	return 0;
+}
+EXPORT_SYMBOL(dma_mmap_from_coherent);