common: add dma_mmap_from_coherent() function

Add a common helper for dma-mapping core for mapping a coherent buffer to userspace. 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>

common: add dma_mmap_from_coherent() function
Add a common helper for dma-mapping core for mapping a coherent buffer to userspace. 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>
Marek Szyprowski
1 parent 76e10d158e
Showing 2 changed files with 45 additions and 1 deletions Side-by-side Diff
drivers/base/dma-coherent.c
include/asm-generic/dma-coherent.h
@@ -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;
  
@@ -176,4 +178,44 @@
 	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);
@@ -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
  */
...	...	@@ -10,6 +10,7 @@
10	10	struct dma_coherent_mem {
11	11	void *virt_base;
12	12	dma_addr_t device_base;
	13	+ phys_addr_t pfn_base;
13	14	int size;
14	15	int flags;
15	16	unsigned long *bitmap;
...	...	@@ -44,6 +45,7 @@
44	45
45	46	dev->dma_mem->virt_base = mem_base;
46	47	dev->dma_mem->device_base = device_addr;
	48	+ dev->dma_mem->pfn_base = PFN_DOWN(bus_addr);
47	49	dev->dma_mem->size = pages;
48	50	dev->dma_mem->flags = flags;
49	51
...	...	@@ -176,4 +178,44 @@
176	178	return 0;
177	179	}
178	180	EXPORT_SYMBOL(dma_release_from_coherent);
	181	+
	182	+/**
	183	+ * dma_mmap_from_coherent() - try to mmap the memory allocated from
	184	+ * per-device coherent memory pool to userspace
	185	+ * @dev: device from which the memory was allocated
	186	+ * @vma: vm_area for the userspace memory
	187	+ * @vaddr: cpu address returned by dma_alloc_from_coherent
	188	+ * @size: size of the memory buffer allocated by dma_alloc_from_coherent
	189	+ *
	190	+ * This checks whether the memory was allocated from the per-device
	191	+ * coherent memory pool and if so, maps that memory to the provided vma.
	192	+ *
	193	+ * Returns 1 if we correctly mapped the memory, or 0 if
	194	+ * dma_release_coherent() should proceed with mapping memory from
	195	+ * generic pools.
	196	+ */
	197	+int dma_mmap_from_coherent(struct device dev, struct vm_area_struct vma,
	198	+ void vaddr, size_t size, int ret)
	199	+{
	200	+ struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
	201	+
	202	+ if (mem && vaddr >= mem->virt_base && vaddr + size <=
	203	+ (mem->virt_base + (mem->size << PAGE_SHIFT))) {
	204	+ unsigned long off = vma->vm_pgoff;
	205	+ int start = (vaddr - mem->virt_base) >> PAGE_SHIFT;
	206	+ int user_count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
	207	+ int count = size >> PAGE_SHIFT;
	208	+
	209	+ *ret = -ENXIO;
	210	+ if (off < count && user_count <= count - off) {
	211	+ unsigned pfn = mem->pfn_base + start + off;
	212	+ *ret = remap_pfn_range(vma, vma->vm_start, pfn,
	213	+ user_count << PAGE_SHIFT,
	214	+ vma->vm_page_prot);
	215	+ }
	216	+ return 1;
	217	+ }
	218	+ return 0;
	219	+}
	220	+EXPORT_SYMBOL(dma_mmap_from_coherent);
...	...	@@ -3,13 +3,15 @@
3	3
4	4	#ifdef CONFIG_HAVE_GENERIC_DMA_COHERENT
5	5	/*
6		- * These two functions are only for dma allocator.
	6	+ * These three functions are only for dma allocator.
7	7	* Don't use them in device drivers.
8	8	*/
9	9	int dma_alloc_from_coherent(struct device *dev, ssize_t size,
10	10	dma_addr_t dma_handle, void *ret);
11	11	int dma_release_from_coherent(struct device dev, int order, void vaddr);
12	12
	13	+int dma_mmap_from_coherent(struct device dev, struct vm_area_struct vma,
	14	+ void cpu_addr, size_t size, int ret);
13	15	/*
14	16	* Standard interface
15	17	*/