Signed-off-by: Gerd Hoffmann kraxel@redhat.com --- include/uapi/linux/udmabuf.h | 52 ++++++++++++++++++++++++++-- Documentation/driver-api/dma-buf.rst | 8 +++++ 2 files changed, 57 insertions(+), 3 deletions(-)

diff --git a/include/uapi/linux/udmabuf.h b/include/uapi/linux/udmabuf.h index 46b6532ed855..9fe440abf2f9 100644 --- a/include/uapi/linux/udmabuf.h +++ b/include/uapi/linux/udmabuf.h @@ -5,8 +5,39 @@ #include <linux/types.h> #include <linux/ioctl.h>

+/** + * DOC: udmabuf + * + * udmabuf is a device driver which allows userspace to create + * dmabufs. The memory used for these dmabufs must be backed by + * memfd. The memfd must have F_SEAL_SHRINK and it must not have + * F_SEAL_WRITE. + * + * The driver has two ioctls, one to create a dmabuf from a single + * memory block and one to create a dmabuf from a list of memory + * blocks. + * + * UDMABUF_CREATE - _IOW('u', 0x42, udmabuf_create) + * + * UDMABUF_CREATE_LIST - _IOW('u', 0x43, udmabuf_create_list) + */ + +#define UDMABUF_CREATE _IOW('u', 0x42, struct udmabuf_create) +#define UDMABUF_CREATE_LIST _IOW('u', 0x43, struct udmabuf_create_list) + #define UDMABUF_FLAGS_CLOEXEC 0x01

+/** + * struct udmabuf_create - create a dmabuf from a single memory block. + * + * @memfd: The file handle. + * @offset: Start of the buffer (from memfd start). + * Must be page aligned. + * @size: Size of the buffer. Must be rounded to page size. + * + * @flags: + * UDMABUF_FLAGS_CLOEXEC: set CLOEXEC flag for the dmabuf. + */ struct udmabuf_create { __u32 memfd; __u32 flags; @@ -14,6 +45,15 @@ struct udmabuf_create { __u64 size; };

+/** + * struct udmabuf_create_item - one memory block list item. + * + * @memfd: The file handle. + * @__pad: Padding field (unused). + * @offset: Start of the buffer (from memfd start). + * Must be page aligned. + * @size: Size of the buffer. Must be rounded to page size. + */ struct udmabuf_create_item { __u32 memfd; __u32 __pad; @@ -21,13 +61,19 @@ struct udmabuf_create_item { __u64 size; };

+/** + * struct udmabuf_create_list - create a dmabuf from a memory block list. + * + * @count: The number of list elements. + * @list: The memory block list + * + * @flags: + * UDMABUF_FLAGS_CLOEXEC: set CLOEXEC flag for the dmabuf. + */ struct udmabuf_create_list { __u32 flags; __u32 count; struct udmabuf_create_item list[]; };

-#define UDMABUF_CREATE _IOW('u', 0x42, struct udmabuf_create) -#define UDMABUF_CREATE_LIST _IOW('u', 0x43, struct udmabuf_create_list) - #endif /* _UAPI_LINUX_UDMABUF_H */ diff --git a/Documentation/driver-api/dma-buf.rst b/Documentation/driver-api/dma-buf.rst index b541e97c7ab1..1f62c30a14b0 100644 --- a/Documentation/driver-api/dma-buf.rst +++ b/Documentation/driver-api/dma-buf.rst @@ -166,3 +166,11 @@ DMA Fence uABI/Sync File .. kernel-doc:: include/linux/sync_file.h :internal:

+Userspace DMA Buffer driver +~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +.. kernel-doc:: include/uapi/linux/udmabuf.h + :doc: udmabuf + +.. kernel-doc:: include/uapi/linux/udmabuf.h + :internal: