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Subject[PATCH v3 1/3] udmabuf: add documentation
Date
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
include/uapi/linux/udmabuf.h | 51 +++++++++++++++++++++++++++++++++---
Documentation/driver-api/dma-buf.rst | 8 ++++++
2 files changed, 56 insertions(+), 3 deletions(-)

diff --git a/include/uapi/linux/udmabuf.h b/include/uapi/linux/udmabuf.h
index 46b6532ed8..281e2c52f1 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 +45,14 @@ struct udmabuf_create {
__u64 size;
};

+/**
+ * struct udmabuf_create_item - one memory block list item.
+ *
+ * @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.
+ */
struct udmabuf_create_item {
__u32 memfd;
__u32 __pad;
@@ -21,13 +60,19 @@ 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 b541e97c7a..1f62c30a14 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:
--
2.9.3
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