@@ -7,6 +7,7 @@
#define __DMA_BUF_MAP_H__
#include <linux/io.h>
+#include <linux/string.h>
/**
* DOC: overview
@@ -32,6 +33,14 @@
* accessing the buffer. Use the returned instance and the helper functions
* to access the buffer's memory in the correct way.
*
+ * The type :c:type:`struct dma_buf_map <dma_buf_map>` and its helpers are
+ * actually independent from the dma-buf infrastructure. When sharing buffers
+ * among devices, drivers have to know the location of the memory to access
+ * the buffers in a safe way. :c:type:`struct dma_buf_map <dma_buf_map>`
+ * solves this problem for dma-buf and its users. If other drivers or
+ * sub-systems require similar functionality, the type could be generalized
+ * and moved to a more prominent header file.
+ *
* Open-coding access to :c:type:`struct dma_buf_map <dma_buf_map>` is
* considered bad style. Rather then accessing its fields directly, use one
* of the provided helper functions, or implement your own. For example,
@@ -51,6 +60,14 @@
*
* dma_buf_map_set_vaddr_iomem(&map. 0xdeadbeaf);
*
+ * Instances of struct dma_buf_map do not have to be cleaned up, but
+ * can be cleared to NULL with dma_buf_map_clear(). Cleared mappings
+ * always refer to system memory.
+ *
+ * .. code-block:: c
+ *
+ * dma_buf_map_clear(&map);
+ *
* Test if a mapping is valid with either dma_buf_map_is_set() or
* dma_buf_map_is_null().
*
@@ -73,17 +90,19 @@
* if (dma_buf_map_is_equal(&sys_map, &io_map))
* // always false
*
- * Instances of struct dma_buf_map do not have to be cleaned up, but
- * can be cleared to NULL with dma_buf_map_clear(). Cleared mappings
- * always refer to system memory.
+ * A set up instance of struct dma_buf_map can be used to access or manipulate
+ * the buffer memory. Depending on the location of the memory, the provided
+ * helpers will pick the correct operations. Data can be copied into the memory
+ * with dma_buf_map_memcpy_to(). The address can be manipulated with
+ * dma_buf_map_incr().
*
- * The type :c:type:`struct dma_buf_map <dma_buf_map>` and its helpers are
- * actually independent from the dma-buf infrastructure. When sharing buffers
- * among devices, drivers have to know the location of the memory to access
- * the buffers in a safe way. :c:type:`struct dma_buf_map <dma_buf_map>`
- * solves this problem for dma-buf and its users. If other drivers or
- * sub-systems require similar functionality, the type could be generalized
- * and moved to a more prominent header file.
+ * .. code-block:: c
+ *
+ * const void *src = ...; // source buffer
+ * size_t len = ...; // length of src
+ *
+ * dma_buf_map_memcpy_to(&map, src, len);
+ * dma_buf_map_incr(&map, len); // go to first byte after the memcpy
*/
/**
@@ -210,4 +229,38 @@ static inline void dma_buf_map_clear(struct dma_buf_map *map)
}
}
+/**
+ * dma_buf_map_memcpy_to - Memcpy into dma-buf mapping
+ * @dst: The dma-buf mapping structure
+ * @src: The source buffer
+ * @len: The number of byte in src
+ *
+ * Copies data into a dma-buf mapping. The source buffer is in system
+ * memory. Depending on the buffer's location, the helper picks the correct
+ * method of accessing the memory.
+ */
+static inline void dma_buf_map_memcpy_to(struct dma_buf_map *dst, const void *src, size_t len)
+{
+ if (dst->is_iomem)
+ memcpy_toio(dst->vaddr_iomem, src, len);
+ else
+ memcpy(dst->vaddr, src, len);
+}
+
+/**
+ * dma_buf_map_incr - Increments the address stored in a dma-buf mapping
+ * @map: The dma-buf mapping structure
+ * @incr: The number of bytes to increment
+ *
+ * Increments the address stored in a dma-buf mapping. Depending on the
+ * buffer's location, the correct value will be updated.
+ */
+static inline void dma_buf_map_incr(struct dma_buf_map *map, size_t incr)
+{
+ if (map->is_iomem)
+ map->vaddr_iomem += incr;
+ else
+ map->vaddr += incr;
+}
+
#endif /* __DMA_BUF_MAP_H__ */