dma-buf-map: Add memcpy and pointer-increment interfaces

#define __DMA_BUF_MAP_H__

#include <linux/io.h>

#include <linux/string.h>

/**

 * DOC: overview

 * 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,

 *

 *	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().

 *

 *	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

 */

/**

	}

}

/**

 * 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__ */