media: videobuf2: Add new uAPI for DVB streaming I/O

Adds a new uAPI for DVB to use streaming I/O which is implemented
based on videobuf2, using those new ioctls:

- DMX_REQBUFS:  Request kernel to allocate buffers which count and size
	        are dedicated by user.
- DMX_QUERYBUF: Get the buffer information like a memory offset which
		will mmap() and be shared with user-space.
- DMX_EXPBUF:   Just for testing whether buffer-exporting success or not.
- DMX_QBUF:     Pass the buffer to kernel-space.
- DMX_DQBUF:    Get back the buffer which may contain TS data.

Originally developed by: Junghak Sung <jh1009.sung@samsung.com>, as
seen at:
	https://patchwork.linuxtv.org/patch/31613/
	https://patchwork.kernel.org/patch/7334301/

The original patch was written before merging VB2-core functionalities
upstream. When such series was added, several adjustments were made,
fixing some issues with	V4L2, causing the original patch to be
non-trivially rebased.

After rebased, a few bugs in the patch were fixed. The patch was
also enhanced it and polling functionality got added.

The main changes over the original patch are:

dvb_vb2_fill_buffer():
	- Set the size of the outgoing buffer after while loop using
	  vb2_set_plane_payload;

	- Added NULL check for source buffer as per normal convention
	  of demux driver, this is called twice, first time with valid
	  buffer second time with NULL pointer, if its not handled,
	  it will result in  crash

	- Restricted spinlock for only list_* operations

dvb_vb2_init():
	- Restricted q->io_modes to only VB2_MMAP as its the only
	  supported mode

dvb_vb2_release():
	- Replaced the && in if condiion with &, because otherwise
	  it was always getting satisfied.

dvb_vb2_stream_off():
	- Added list_del code for enqueud buffers upon stream off

dvb_vb2_poll():
	- Added this new function in order to support polling

dvb_demux_poll() and dvb_dvr_poll()
	- dvb_vb2_poll() is now called from these functions

- Ported this patch and latest videobuf2 to lower kernel versions and
  tested auto scan.

Co-developed-by: Junghak Sung <jh1009.sung@samsung.com>

[mchehab@s-opensource.com: checkpatch fixes]
Signed-off-by: Junghak Sung <jh1009.sung@samsung.com>
Signed-off-by: Geunyoung Kim <nenggun.kim@samsung.com>
Acked-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Acked-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Satendra Singh Thakur <satendra.t@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

1 files changed, 65 insertions, 1 deletions

diff --git a/include/uapi/linux/dvb/dmx.h b/include/uapi/linux/dvb/dmx.h
index c10f1324b4ca..e212aa18ad78 100644
--- a/include/uapi/linux/dvb/dmx.h
+++ b/include/uapi/linux/dvb/dmx.h
@@ -211,6 +211,64 @@ struct dmx_stc {
         __u64 stc;
 };
 
+/**
+ * struct dmx_buffer - dmx buffer info
+ *
+ * @index:      id number of the buffer
+ * @bytesused:  number of bytes occupied by data in the buffer (payload);
+ * @offset:     for buffers with memory == DMX_MEMORY_MMAP;
+ *              offset from the start of the device memory for this plane,
+ *              (or a "cookie" that should be passed to mmap() as offset)
+ * @length:     size in bytes of the buffer
+ *
+ * Contains data exchanged by application and driver using one of the streaming
+ * I/O methods.
+ */
+struct dmx_buffer {
+        __u32                   index;
+        __u32                   bytesused;
+        __u32                   offset;
+        __u32                   length;
+        __u32                   reserved[4];
+};
+
+/**
+ * struct dmx_requestbuffers - request dmx buffer information
+ *
+ * @count:      number of requested buffers,
+ * @size:       size in bytes of the requested buffer
+ *
+ * Contains data used for requesting a dmx buffer.
+ * All reserved fields must be set to zero.
+ */
+struct dmx_requestbuffers {
+        __u32                   count;
+        __u32                   size;
+        __u32                   reserved[2];
+};
+
+/**
+ * struct dmx_exportbuffer - export of dmx buffer as DMABUF file descriptor
+ *
+ * @index:      id number of the buffer
+ * @flags:      flags for newly created file, currently only O_CLOEXEC is
+ *              supported, refer to manual of open syscall for more details
+ * @fd:         file descriptor associated with DMABUF (set by driver)
+ *
+ * Contains data used for exporting a dmx buffer as DMABUF file descriptor.
+ * The buffer is identified by a 'cookie' returned by DMX_QUERYBUF
+ * (identical to the cookie used to mmap() the buffer to userspace). All
+ * reserved fields must be set to zero. The field reserved0 is expected to
+ * become a structure 'type' allowing an alternative layout of the structure
+ * content. Therefore this field should not be used for any other extensions.
+ */
+struct dmx_exportbuffer {
+        __u32           index;
+        __u32           flags;
+        __s32           fd;
+        __u32           reserved[5];
+};
+
 #define DMX_START                _IO('o', 41)
 #define DMX_STOP                 _IO('o', 42)
 #define DMX_SET_FILTER           _IOW('o', 43, struct dmx_sct_filter_params)
@@ -231,4 +289,10 @@ typedef struct dmx_filter dmx_filter_t;
 
 #endif
 
-#endif /* _UAPI_DVBDMX_H_ */
+#define DMX_REQBUFS              _IOWR('o', 60, struct dmx_requestbuffers)
+#define DMX_QUERYBUF             _IOWR('o', 61, struct dmx_buffer)
+#define DMX_EXPBUF               _IOWR('o', 62, struct dmx_exportbuffer)
+#define DMX_QBUF                 _IOWR('o', 63, struct dmx_buffer)
+#define DMX_DQBUF                _IOWR('o', 64, struct dmx_buffer)
+
+#endif /* _DVBDMX_H_ */