[PATCH 2/6] v4l: add buffer exporting via shrbuf

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From: Tomasz Stanislawski <t.stanislaws@xxxxxxxxxxx>

This patch adds extension to V4L2 api. It allow to export a mmap buffer as file descriptor. New ioctl VIDIOC_EXPBUF is added. It takes a buffer offset used by
mmap and return a file descriptor on success.

Signed-off-by: Tomasz Stanislawski <t.stanislaws@xxxxxxxxxxx>
Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
---
 drivers/media/video/v4l2-ioctl.c |   10 ++++++++++
 include/linux/videodev2.h        |    8 ++++++++
 include/media/v4l2-ioctl.h       |    1 +
 3 files changed, 19 insertions(+), 0 deletions(-)

diff --git a/drivers/media/video/v4l2-ioctl.c b/drivers/media/video/v4l2-ioctl.c
index 660b486..0a19fd4 100644
--- a/drivers/media/video/v4l2-ioctl.c
+++ b/drivers/media/video/v4l2-ioctl.c
@@ -1145,6 +1145,16 @@ static long __video_do_ioctl(struct file *file,
             dbgbuf(cmd, vfd, p);
         break;
     }
+    case VIDIOC_EXPBUF:
+    {
+        unsigned int *p = arg;
+
+        if (!ops->vidioc_expbuf)
+            break;
+
+        ret = ops->vidioc_expbuf(file, fh, *p);
+        break;
+    }
     case VIDIOC_DQBUF:
     {
         struct v4l2_buffer *p = arg;
diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
index 7c77c4e..cae7908 100644
--- a/include/linux/videodev2.h
+++ b/include/linux/videodev2.h
@@ -185,6 +185,7 @@ enum v4l2_memory {
     V4L2_MEMORY_MMAP             = 1,
     V4L2_MEMORY_USERPTR          = 2,
     V4L2_MEMORY_OVERLAY          = 3,
+    V4L2_MEMORY_SHRBUF           = 4,
 };

 /* see also http://vektor.theorem.ca/graphics/ycbcr/ */
@@ -564,6 +565,8 @@ struct v4l2_requestbuffers {
  *            should be passed to mmap() called on the video node)
* @userptr: when memory is V4L2_MEMORY_USERPTR, a userspace pointer
  *            pointing to this plane
+ * @fd:            when memory is V4L2_MEMORY_SHRBUF, a userspace file
+ *            descriptor associated with this plane
  * @data_offset:    offset in the plane to the start of data; usually 0,
  *            unless there is a header in front of the data
  *
@@ -578,6 +581,7 @@ struct v4l2_plane {
     union {
         __u32        mem_offset;
         unsigned long    userptr;
+        int fd;
     } m;
     __u32            data_offset;
     __u32            reserved[11];
@@ -600,6 +604,8 @@ struct v4l2_plane {
  *        (or a "cookie" that should be passed to mmap() as offset)
* @userptr: for non-multiplanar buffers with memory == V4L2_MEMORY_USERPTR;
  *        a userspace pointer pointing to this buffer
+ * @fd: for non-multiplanar buffers with memory == V4L2_MEMORY_SHRBUF;
+ *        a userspace file descriptor associated with this buffer
* @planes: for multiplanar buffers; userspace pointer to the array of plane
  *        info structs for this buffer
* @length: size in bytes of the buffer (NOT its payload) for single-plane
@@ -626,6 +632,7 @@ struct v4l2_buffer {
         __u32           offset;
         unsigned long   userptr;
         struct v4l2_plane *planes;
+        int fd;
     } m;
     __u32            length;
     __u32            input;
@@ -1868,6 +1875,7 @@ struct v4l2_dbg_chip_ident {
 #define VIDIOC_S_FBUF         _IOW('V', 11, struct v4l2_framebuffer)
 #define VIDIOC_OVERLAY         _IOW('V', 14, int)
 #define VIDIOC_QBUF        _IOWR('V', 15, struct v4l2_buffer)
+#define VIDIOC_EXPBUF        _IOWR('V', 16, unsigned int)
 #define VIDIOC_DQBUF        _IOWR('V', 17, struct v4l2_buffer)
 #define VIDIOC_STREAMON         _IOW('V', 18, int)
 #define VIDIOC_STREAMOFF     _IOW('V', 19, int)
diff --git a/include/media/v4l2-ioctl.h b/include/media/v4l2-ioctl.h
index dd9f1e7..20932e3 100644
--- a/include/media/v4l2-ioctl.h
+++ b/include/media/v4l2-ioctl.h
@@ -121,6 +121,7 @@ struct v4l2_ioctl_ops {
int (*vidioc_querybuf)(struct file *file, void *fh, struct v4l2_buffer *b); int (*vidioc_qbuf) (struct file *file, void *fh, struct v4l2_buffer *b); int (*vidioc_dqbuf) (struct file *file, void *fh, struct v4l2_buffer *b); + int (*vidioc_expbuf) (struct file *file, void *fh, unsigned int offset);


     int (*vidioc_overlay) (struct file *file, void *fh, unsigned int i);
--
1.7.6



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