Re: [Xen-devel] swiotlb-xen question

[Oleksandr Dmytryshyn <oleksandr.dmytryshyn@xxxxxxxxxxxxxxx>]

From f52bafc1ba51324ca5044df22778aacf815c59bf Mon Sep 17 00:00:00 2001
From: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Date: Fri, 4 Apr 2014 12:16:27 +0300
Subject: [PATCH] swiotlb-xen: implement xen_swiotlb_dma_mmap callback

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

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Signed-off-by: Oleksandr Dmytryshyn <oleksandr.dmytryshyn@xxxxxxxxxxxxxxx>

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,

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