Add a common helper for dma-mapping core for mapping a coherent buffer
to userspace.
Reported-by: Subash Patel <subashrp@xxxxxxxxx>
Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Acked-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
---
drivers/base/dma-coherent.c | 42 ++++++++++++++++++++++++++++++++++++
include/asm-generic/dma-coherent.h | 4 ++-
2 files changed, 45 insertions(+), 1 deletions(-)
diff --git a/drivers/base/dma-coherent.c b/drivers/base/dma-coherent.c
index bb0025c..1b85949 100644
--- a/drivers/base/dma-coherent.c
+++ b/drivers/base/dma-coherent.c
@@ -10,6 +10,7 @@
struct dma_coherent_mem {
void *virt_base;
dma_addr_t device_base;
+ phys_addr_t pfn_base;
int size;
int flags;
unsigned long *bitmap;
@@ -44,6 +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(bus_addr);
dev->dma_mem->size = pages;
dev->dma_mem->flags = flags;
@@ -176,3 +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
+ *
+ * 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
+ * dma_release_coherent() 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 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);
diff --git a/include/asm-generic/dma-coherent.h b/include/asm-generic/dma-coherent.h
index 85a3ffa..abfb268 100644
--- a/include/asm-generic/dma-coherent.h
+++ b/include/asm-generic/dma-coherent.h
@@ -3,13 +3,15 @@
#ifdef CONFIG_HAVE_GENERIC_DMA_COHERENT
/*
- * These two functions are only for dma allocator.
+ * These three functions are only for dma allocator.
* Don't use them in device drivers.
*/
int dma_alloc_from_coherent(struct device *dev, ssize_t size,
dma_addr_t *dma_handle, void **ret);
int dma_release_from_coherent(struct device *dev, int order, void *vaddr);
+int dma_mmap_from_coherent(struct device *dev, struct vm_area_struct *vma,
+ void *cpu_addr, size_t size, int *ret);
/*
* Standard interface
*/
--
1.7.1.569.g6f426
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