[Xen-devel] [PATCH] swiotlb-xen: implement xen_swiotlb_dma_mmap callback

[Oleksandr Dmytryshyn <oleksandr.dmytryshyn@xxxxxxxxxxxxxxx>]

From: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>

This function creates userspace mapping for the DMA-coherent memory.

Change-Id: If22f75996278063394f628f57869ccd3ca09de7c
Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Signed-off-by: Oleksandr Dmytryshyn <oleksandr.dmytryshyn@xxxxxxxxxxxxxxx>
---
 arch/arm/xen/mm.c         |  1 +
 drivers/xen/swiotlb-xen.c | 36 ++++++++++++++++++++++++++++++++++++
 include/xen/swiotlb-xen.h |  5 +++++
 3 files changed, 42 insertions(+)

diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c
index b0e77de..91408b1 100644
--- a/arch/arm/xen/mm.c
+++ b/arch/arm/xen/mm.c
@@ -48,6 +48,7 @@ static struct dma_map_ops xen_swiotlb_dma_ops = {
        .sync_sg_for_device = xen_swiotlb_sync_sg_for_device,
        .map_sg = xen_swiotlb_map_sg_attrs,
        .unmap_sg = xen_swiotlb_unmap_sg_attrs,
+       .mmap = xen_swiotlb_dma_mmap,
        .map_page = xen_swiotlb_map_page,
        .unmap_page = xen_swiotlb_unmap_page,
        .dma_supported = xen_swiotlb_dma_supported,
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 5403855..acf0c06 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -407,6 +407,42 @@ dma_addr_t xen_swiotlb_map_page(struct device *dev, struct 
page *page,
 EXPORT_SYMBOL_GPL(xen_swiotlb_map_page);
 
 /*
+ * Create userspace mapping for the DMA-coherent memory.
+ */
+int xen_swiotlb_dma_mmap(struct device *dev, struct vm_area_struct *vma,
+                        void *cpu_addr, dma_addr_t dma_addr, size_t size,
+                        struct dma_attrs *attrs)
+{
+       int ret = -ENXIO;
+#ifdef CONFIG_MMU
+       unsigned long nr_vma_pages = (vma->vm_end - vma->vm_start) >> 
PAGE_SHIFT;
+       unsigned long nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
+       unsigned long pfn = PFN_DOWN(xen_bus_to_phys(dma_addr));
+       unsigned long off = vma->vm_pgoff;
+       pgprot_t prot = vma->vm_page_prot;
+
+       prot = dma_get_attr(DMA_ATTR_WRITE_COMBINE, attrs) ?
+                           pgprot_writecombine(prot) :
+                           pgprot_dmacoherent(prot);
+
+       vma->vm_page_prot = prot;
+
+       if (dma_mmap_from_coherent(dev, vma, cpu_addr, size, &ret))
+               return ret;
+
+       if (off < nr_pages && nr_vma_pages <= (nr_pages - off)) {
+               ret = remap_pfn_range(vma, vma->vm_start,
+                                       pfn + off,
+                                       vma->vm_end - vma->vm_start,
+                                       vma->vm_page_prot);
+       }
+#endif  /* CONFIG_MMU */
+
+       return ret;
+}
+EXPORT_SYMBOL_GPL(xen_swiotlb_dma_mmap);
+
+/*
  * Unmap a single streaming mode DMA translation.  The dma_addr and size must
  * match what was provided for in a previous xen_swiotlb_map_page call.  All
  * other usages are undefined.
diff --git a/include/xen/swiotlb-xen.h b/include/xen/swiotlb-xen.h
index 7b64465..930fa94 100644
--- a/include/xen/swiotlb-xen.h
+++ b/include/xen/swiotlb-xen.h
@@ -15,6 +15,11 @@ xen_swiotlb_free_coherent(struct device *hwdev, size_t size,
                          void *vaddr, dma_addr_t dma_handle,
                          struct dma_attrs *attrs);
 
+extern int
+xen_swiotlb_dma_mmap(struct device *dev, struct vm_area_struct *vma,
+                    void *cpu_addr, dma_addr_t dma_addr, size_t size,
+                    struct dma_attrs *attrs);
+
 extern dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
                                       unsigned long offset, size_t size,
                                       enum dma_data_direction dir,
-- 
1.8.2.rc2


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