With the new dmx mmap interface, those two syscalls are now
handled by the subsystem. Document them.
This patch is based on the V4L2 text for those ioctls.
Signed-off-by: Mauro Carvalho Chehab <mche...@s-opensource.com>
---
Documentation/media/uapi/dvb/dmx-mmap.rst | 116 ++++++++++++++++++++++++++++
Documentation/media/uapi/dvb/dmx-munmap.rst | 54 +++++++++++++
Documentation/media/uapi/dvb/dmx_fcalls.rst | 2 +
3 files changed, 172 insertions(+)
create mode 100644 Documentation/media/uapi/dvb/dmx-mmap.rst
create mode 100644 Documentation/media/uapi/dvb/dmx-munmap.rst
diff --git a/Documentation/media/uapi/dvb/dmx-mmap.rst
b/Documentation/media/uapi/dvb/dmx-mmap.rst
new file mode 100644
index 000000000000..15d107348b9f
--- /dev/null
+++ b/Documentation/media/uapi/dvb/dmx-mmap.rst
@@ -0,0 +1,116 @@
+.. _dmx-mmap:
+
+*****************
+Digital TV mmap()
+*****************
+
+Name
+====
+
+dmx-mmap - Map device memory into application address space
+
+.. warning:: this API is still experimental
+
+Synopsis
+========
+
+.. code-block:: c
+
+ #include <unistd.h>
+ #include <sys/mman.h>
+
+
+.. c:function:: void *mmap( void *start, size_t length, int prot, int flags,
int fd, off_t offset )
+ :name: dmx-mmap
+
+Arguments
+=========
+
+``start``
+ Map the buffer to this address in the application's address space.
+ When the ``MAP_FIXED`` flag is specified, ``start`` must be a
+ multiple of the pagesize and mmap will fail when the specified
+ address cannot be used. Use of this option is discouraged;
+ applications should just specify a ``NULL`` pointer here.
+
+``length``
+ Length of the memory area to map. This must be a multiple of the
+ DVB packet length (188, on most drivers).
+
+``prot``
+ The ``prot`` argument describes the desired memory protection.
+ Regardless of the device type and the direction of data exchange it
+ should be set to ``PROT_READ`` | ``PROT_WRITE``, permitting read
+ and write access to image buffers. Drivers should support at least
+ this combination of flags.
+
+``flags``
+ The ``flags`` parameter specifies the type of the mapped object,
+ mapping options and whether modifications made to the mapped copy of
+ the page are private to the process or are to be shared with other
+ references.
+
+ ``MAP_FIXED`` requests that the driver selects no other address than
+ the one specified. If the specified address cannot be used,
+ :ref:`mmap() <dmx-mmap>` will fail. If ``MAP_FIXED`` is specified,
+ ``start`` must be a multiple of the pagesize. Use of this option is
+ discouraged.
+
+ One of the ``MAP_SHARED`` or ``MAP_PRIVATE`` flags must be set.
+ ``MAP_SHARED`` allows applications to share the mapped memory with
+ other (e. g. child-) processes.
+
+ .. note::
+
+ The Linux Digital TV applications should not set the
+ ``MAP_PRIVATE``, ``MAP_DENYWRITE``, ``MAP_EXECUTABLE`` or ``MAP_ANON``
+ flags.
+
+``fd``
+ File descriptor returned by :ref:`open() <dmx_fopen>`.
+
+``offset``
+ Offset of the buffer in device memory, as returned by
+ :ref:`DMX_QUERYBUF` ioctl.
+
+
+Description
+===========
+
+The :ref:`mmap() <dmx-mmap>` function asks to map ``length`` bytes starting at
+``offset`` in the memory of the device specified by ``fd`` into the
+application address space, preferably at address ``start``. This latter
+address is a hint only, and is usually specified as 0.
+
+Suitable length and offset parameters are queried with the
+:ref:`DMX_QUERYBUF` ioctl. Buffers must be allocated with the
+:ref:`DMX_REQBUFS` ioctl before they can be queried.
+
+To unmap buffers the :ref:`munmap() <dmx-munmap>` function is used.
+
+
+Return Value
+============
+
+On success :ref:`mmap() <dmx-mmap>` returns a pointer to the mapped buffer. On
+error ``MAP_FAILED`` (-1) is returned, and the ``errno`` variable is set
+appropriately. Possible error codes are:
+
+EBADF
+ ``fd`` is not a valid file descriptor.
+
+EACCES
+ ``fd`` is not open for reading and writing.
+
+EINVAL
+ The ``start`` or ``length`` or ``offset`` are not suitable. (E. g.
+ they are too large, or not aligned on a ``PAGESIZE`` boundary.)
+
+ The ``flags`` or ``prot`` value is not supported.
+
+ No buffers have been allocated with the
+ :ref:`DMX_REQBUFS` ioctl.
+
+ENOMEM
+ Not enough physical or virtual memory was available to complete the
+ request.
diff --git a/Documentation/media/uapi/dvb/dmx-munmap.rst
b/Documentation/media/uapi/dvb/dmx-munmap.rst
new file mode 100644
index 000000000000..d77218732bb6
--- /dev/null
+++ b/Documentation/media/uapi/dvb/dmx-munmap.rst
@@ -0,0 +1,54 @@
+.. _dmx-munmap:
+
+************
+DVB munmap()
+************
+
+Name
+====
+
+dmx-munmap - Unmap device memory
+
+.. warning:: This API is still experimental.
+
+
+Synopsis
+========
+
+.. code-block:: c
+
+ #include <unistd.h>
+ #include <sys/mman.h>
+
+
+.. c:function:: int munmap( void *start, size_t length )
+ :name: dmx-munmap
+
+Arguments
+=========
+
+``start``
+ Address of the mapped buffer as returned by the
+ :ref:`mmap() <dmx-mmap>` function.
+
+``length``
+ Length of the mapped buffer. This must be the same value as given to
+ :ref:`mmap() <dmx-mmap>`.
+
+
+Description
+===========
+
+Unmaps a previously with the :ref:`mmap() <dmx-mmap>` function mapped
+buffer and frees it, if possible.
+
+
+Return Value
+============
+
+On success :ref:`munmap() <dmx-munmap>` returns 0, on failure -1 and the
+``errno`` variable is set appropriately:
+
+EINVAL
+ The ``start`` or ``length`` is incorrect, or no buffers have been
+ mapped yet.
diff --git a/Documentation/media/uapi/dvb/dmx_fcalls.rst
b/Documentation/media/uapi/dvb/dmx_fcalls.rst
index a17289143220..db19df6dbf70 100644
--- a/Documentation/media/uapi/dvb/dmx_fcalls.rst
+++ b/Documentation/media/uapi/dvb/dmx_fcalls.rst
@@ -13,6 +13,8 @@ Demux Function Calls
dmx-fclose
dmx-fread
dmx-fwrite
+ dmx-mmap
+ dmx-munmap
dmx-start
dmx-stop
dmx-set-filter
--
2.14.3
