mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-06 02:50:43 +00:00
dma-buf-map: Add memcpy and pointer-increment interfaces
To do framebuffer updates, one needs memcpy from system memory and a pointer-increment function. Add both interfaces with documentation. v5: * include <linux/string.h> to build on sparc64 (Sam) Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> Reviewed-by: Sam Ravnborg <sam@ravnborg.org> Tested-by: Sam Ravnborg <sam@ravnborg.org> Link: https://patchwork.freedesktop.org/patch/msgid/20201103093015.1063-10-tzimmermann@suse.de
This commit is contained in:
parent
a859555689
commit
b4e7090c24
1 changed files with 63 additions and 10 deletions
|
@ -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__ */
|
||||
|
|
Loading…
Reference in a new issue