common: add dma_mmap_from_coherent() function
Add a common helper for dma-mapping core for mapping a coherent buffer
to userspace.
Change-Id: I9b67d53b50f4761455ff66634d65e6510faa62de
Reported-by: Subash Patel <subashrp@gmail.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Tested-By: Subash Patel <subash.ramaswamy@linaro.org>
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
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 @@
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 @@
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);