[PATCH 1/6 v4] V4L: add two new ioctl()s for multi-size videobuffer management

[Guennadi Liakhovetski <g.liakhovetski@gmx.de>]

A possibility to preallocate and initialise buffers of different sizes
in V4L2 is required for an efficient implementation of asnapshot mode.
This patch adds two new ioctl()s: VIDIOC_CREATE_BUFS and
VIDIOC_PREPARE_BUF and defines respective data structures.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
---

v4:

1. CREATE_BUFS now takes an array of plane sizes and a fourcc code in its 
   argument, instead of a frame format specification, including 
   documentation update
2. documentation improvements, as suggested by Hans
3. increased reserved fields to 18, as suggested by Sakari

 Documentation/DocBook/media/v4l/io.xml             |   17 ++
 Documentation/DocBook/media/v4l/v4l2.xml           |    2 +
 .../DocBook/media/v4l/vidioc-create-bufs.xml       |  161 ++++++++++++++++++++
 .../DocBook/media/v4l/vidioc-prepare-buf.xml       |   96 ++++++++++++
 drivers/media/video/v4l2-compat-ioctl32.c          |    6 +
 drivers/media/video/v4l2-ioctl.c                   |   26 +++
 include/linux/videodev2.h                          |   18 +++
 include/media/v4l2-ioctl.h                         |    2 +
 8 files changed, 328 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/DocBook/media/v4l/vidioc-create-bufs.xml
 create mode 100644 Documentation/DocBook/media/v4l/vidioc-prepare-buf.xml

diff --git a/Documentation/DocBook/media/v4l/io.xml b/Documentation/DocBook/media/v4l/io.xml
index 227e7ac..ff03dd2 100644
--- a/Documentation/DocBook/media/v4l/io.xml
+++ b/Documentation/DocBook/media/v4l/io.xml
@@ -927,6 +927,23 @@ ioctl is called.</entry>
 Applications set or clear this flag before calling the
 <constant>VIDIOC_QBUF</constant> ioctl.</entry>
 	  </row>
+	  <row>
+	    <entry><constant>V4L2_BUF_FLAG_NO_CACHE_INVALIDATE</constant></entry>
+	    <entry>0x0400</entry>
+	    <entry>Caches do not have to be invalidated for this buffer.
+Typically applications shall use this flag if the data captured in the buffer
+is not going to be touched by the CPU, instead the buffer will, probably, be
+passed on to a DMA-capable hardware unit for further processing or output.
+</entry>
+	  </row>
+	  <row>
+	    <entry><constant>V4L2_BUF_FLAG_NO_CACHE_CLEAN</constant></entry>
+	    <entry>0x0800</entry>
+	    <entry>Caches do not have to be cleaned for this buffer.
+Typically applications shall use this flag for output buffers if the data
+in this buffer has not been created by the CPU but by some DMA-capable unit,
+in which case caches have not been used.</entry>
+	  </row>
 	</tbody>
       </tgroup>
     </table>
diff --git a/Documentation/DocBook/media/v4l/v4l2.xml b/Documentation/DocBook/media/v4l/v4l2.xml
index 0d05e87..06bb179 100644
--- a/Documentation/DocBook/media/v4l/v4l2.xml
+++ b/Documentation/DocBook/media/v4l/v4l2.xml
@@ -462,6 +462,7 @@ and discussions on the V4L mailing list.</revremark>
     &sub-close;
     &sub-ioctl;
     <!-- All ioctls go here. -->
+    &sub-create-bufs;
     &sub-cropcap;
     &sub-dbg-g-chip-ident;
     &sub-dbg-g-register;
@@ -504,6 +505,7 @@ and discussions on the V4L mailing list.</revremark>
     &sub-queryctrl;
     &sub-query-dv-preset;
     &sub-querystd;
+    &sub-prepare-buf;
     &sub-reqbufs;
     &sub-s-hw-freq-seek;
     &sub-streamon;
diff --git a/Documentation/DocBook/media/v4l/vidioc-create-bufs.xml b/Documentation/DocBook/media/v4l/vidioc-create-bufs.xml
new file mode 100644
index 0000000..b37b9a4
--- /dev/null
+++ b/Documentation/DocBook/media/v4l/vidioc-create-bufs.xml
@@ -0,0 +1,161 @@
+<refentry id="vidioc-create-bufs">
+  <refmeta>
+    <refentrytitle>ioctl VIDIOC_CREATE_BUFS</refentrytitle>
+    &manvol;
+  </refmeta>
+
+  <refnamediv>
+    <refname>VIDIOC_CREATE_BUFS</refname>
+    <refpurpose>Create buffers for Memory Mapped or User Pointer I/O</refpurpose>
+  </refnamediv>
+
+  <refsynopsisdiv>
+    <funcsynopsis>
+      <funcprototype>
+	<funcdef>int <function>ioctl</function></funcdef>
+	<paramdef>int <parameter>fd</parameter></paramdef>
+	<paramdef>int <parameter>request</parameter></paramdef>
+	<paramdef>struct v4l2_create_buffers *<parameter>argp</parameter></paramdef>
+      </funcprototype>
+    </funcsynopsis>
+  </refsynopsisdiv>
+
+  <refsect1>
+    <title>Arguments</title>
+
+    <variablelist>
+      <varlistentry>
+	<term><parameter>fd</parameter></term>
+	<listitem>
+	  <para>&fd;</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><parameter>request</parameter></term>
+	<listitem>
+	  <para>VIDIOC_CREATE_BUFS</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><parameter>argp</parameter></term>
+	<listitem>
+	  <para></para>
+	</listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+
+  <refsect1>
+    <title>Description</title>
+
+    <para>This ioctl is used to create buffers for <link linkend="mmap">memory
+mapped</link> or <link linkend="userp">user pointer</link>
+I/O. It can be used as an alternative or in addition to the
+<constant>VIDIOC_REQBUFS</constant> ioctl, when a tighter control over buffers
+is required. This ioctl can be called multiple times to create buffers of
+different sizes.</para>
+
+    <para>To allocate device buffers applications initialize relevant
+fields of the <structname>v4l2_create_buffers</structname> structure.
+They set the <structfield>type</structfield> field  to the respective stream
+or buffer type. <structfield>count</structfield> must be set to the number of
+required buffers. <structfield>memory</structfield> specifies the required I/O
+method. If <structfield>num_planes</structfield> == 0 or all elements of the
+<structfield>sizes</structfield> array are 0, then buffers, suitable for the
+currently configured video format, are allocated, exactly like for the
+<constant>VIDIOC_REQBUFS</constant> ioctl. If
+<structfield>num_planes</structfield> > 0 and at least some of the respective
+<structfield>sizes</structfield> elements are non-zero, this information will be
+used for buffer-allocation. The <structfield>reserved</structfield> array must
+be zeroed. When the ioctl is called with a pointer to this structure the driver
+will attempt to allocate up to the requested number of buffers and store the
+actual number allocated and the starting index in the
+<structfield>count</structfield> and the <structfield>index</structfield>
+fields respectively. On return <structfield>count</structfield> can be smaller
+than the number requested.</para>
+    <para>When the I/O method is not supported the ioctl
+returns an &EINVAL;.</para>
+
+    <table pgwide="1" frame="none" id="v4l2-create-buffers">
+      <title>struct <structname>v4l2_create_buffers</structname></title>
+      <tgroup cols="3">
+	&cs-str;
+	<tbody valign="top">
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>index</structfield></entry>
+	    <entry>The starting buffer index, returned by the driver.</entry>
+	  </row>
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>count</structfield></entry>
+	    <entry>The number of buffers requested or granted.</entry>
+	  </row>
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>type</structfield></entry>
+	    <entry>V4L2 buffer type: one of <constant>V4L2_BUF_TYPE_*</constant>
+values.</entry>
+	  </row>
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>memory</structfield></entry>
+	    <entry>Applications set this field to
+<constant>V4L2_MEMORY_MMAP</constant> or
+<constant>V4L2_MEMORY_USERPTR</constant>.</entry>
+	  </row>
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>fourcc</structfield></entry>
+	    <entry>One of V4L2_PIX_FMT_* FOURCCs of the video data.</entry>
+	  </row>
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>num_planes</structfield></entry>
+	    <entry>Number of planes or 0 to use the current format.</entry>
+	  </row>
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>size[VIDEO_MAX_PLANES]</structfield></entry>
+	    <entry>Explicit sizes of buffers, being created.</entry>
+	  </row>
+	  <row>
+	    <entry>__u32</entry>
+	    <entry><structfield>reserved</structfield>[18]</entry>
+	    <entry>A place holder for future extensions.</entry>
+	  </row>
+	</tbody>
+      </tgroup>
+    </table>
+  </refsect1>
+
+  <refsect1>
+    &return-value;
+
+    <variablelist>
+      <varlistentry>
+	<term><errorcode>ENOMEM</errorcode></term>
+	<listitem>
+	  <para>No memory to allocate buffers for <link linkend="mmap">memory
+mapped</link> I/O.</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><errorcode>EINVAL</errorcode></term>
+	<listitem>
+	  <para>The buffer type (<structfield>type</structfield> field) or the
+requested I/O method (<structfield>memory</structfield>) is not
+supported.</para>
+	</listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+</refentry>
+
+<!--
+Local Variables:
+mode: sgml
+sgml-parent-document: "v4l2.sgml"
+indent-tabs-mode: nil
+End:
+-->
diff --git a/Documentation/DocBook/media/v4l/vidioc-prepare-buf.xml b/Documentation/DocBook/media/v4l/vidioc-prepare-buf.xml
new file mode 100644
index 0000000..509e752
--- /dev/null
+++ b/Documentation/DocBook/media/v4l/vidioc-prepare-buf.xml
@@ -0,0 +1,96 @@
+<refentry id="vidioc-prepare-buf">
+  <refmeta>
+    <refentrytitle>ioctl VIDIOC_PREPARE_BUF</refentrytitle>
+    &manvol;
+  </refmeta>
+
+  <refnamediv>
+    <refname>VIDIOC_PREPARE_BUF</refname>
+    <refpurpose>Prepare a buffer for I/O</refpurpose>
+  </refnamediv>
+
+  <refsynopsisdiv>
+    <funcsynopsis>
+      <funcprototype>
+	<funcdef>int <function>ioctl</function></funcdef>
+	<paramdef>int <parameter>fd</parameter></paramdef>
+	<paramdef>int <parameter>request</parameter></paramdef>
+	<paramdef>struct v4l2_buffer *<parameter>argp</parameter></paramdef>
+      </funcprototype>
+    </funcsynopsis>
+  </refsynopsisdiv>
+
+  <refsect1>
+    <title>Arguments</title>
+
+    <variablelist>
+      <varlistentry>
+	<term><parameter>fd</parameter></term>
+	<listitem>
+	  <para>&fd;</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><parameter>request</parameter></term>
+	<listitem>
+	  <para>VIDIOC_PREPARE_BUF</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><parameter>argp</parameter></term>
+	<listitem>
+	  <para></para>
+	</listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+
+  <refsect1>
+    <title>Description</title>
+
+    <para>Applications can optionally call the
+<constant>VIDIOC_PREPARE_BUF</constant> ioctl to pass ownership of the buffer
+to the driver before actually enqueuing it, using the
+<constant>VIDIOC_QBUF</constant> ioctl, and to prepare it for future I/O.
+Such preparations may include cache invalidation or cleaning. Performing them
+in advance saves time during the actual I/O. In case such cache operations are
+not required, the application can use one of
+<constant>V4L2_BUF_FLAG_NO_CACHE_INVALIDATE</constant> and
+<constant>V4L2_BUF_FLAG_NO_CACHE_CLEAN</constant> flags to skip the respective
+step.</para>
+
+    <para>The <structname>v4l2_buffer</structname> structure is
+specified in <xref linkend="buffer" />.</para>
+  </refsect1>
+
+  <refsect1>
+    &return-value;
+
+    <variablelist>
+      <varlistentry>
+	<term><errorcode>EBUSY</errorcode></term>
+	<listitem>
+	  <para>File I/O is in progress.</para>
+	</listitem>
+      </varlistentry>
+      <varlistentry>
+	<term><errorcode>EINVAL</errorcode></term>
+	<listitem>
+	  <para>The buffer <structfield>type</structfield> is not
+supported, or the <structfield>index</structfield> is out of bounds,
+or no buffers have been allocated yet, or the
+<structfield>userptr</structfield> or
+<structfield>length</structfield> are invalid.</para>
+	</listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+</refentry>
+
+<!--
+Local Variables:
+mode: sgml
+sgml-parent-document: "v4l2.sgml"
+indent-tabs-mode: nil
+End:
+-->
diff --git a/drivers/media/video/v4l2-compat-ioctl32.c b/drivers/media/video/v4l2-compat-ioctl32.c
index 61979b7..ee5eec8 100644
--- a/drivers/media/video/v4l2-compat-ioctl32.c
+++ b/drivers/media/video/v4l2-compat-ioctl32.c
@@ -702,6 +702,7 @@ static int put_v4l2_event32(struct v4l2_event *kp, struct v4l2_event32 __user *u
 #define VIDIOC_S_EXT_CTRLS32    _IOWR('V', 72, struct v4l2_ext_controls32)
 #define VIDIOC_TRY_EXT_CTRLS32  _IOWR('V', 73, struct v4l2_ext_controls32)
 #define	VIDIOC_DQEVENT32	_IOR ('V', 89, struct v4l2_event32)
+#define VIDIOC_PREPARE_BUF32	_IOWR('V', 93, struct v4l2_buffer32)
 
 #define VIDIOC_OVERLAY32	_IOW ('V', 14, s32)
 #define VIDIOC_STREAMON32	_IOW ('V', 18, s32)
@@ -751,6 +752,7 @@ static long do_video_ioctl(struct file *file, unsigned int cmd, unsigned long ar
 	case VIDIOC_S_INPUT32: cmd = VIDIOC_S_INPUT; break;
 	case VIDIOC_G_OUTPUT32: cmd = VIDIOC_G_OUTPUT; break;
 	case VIDIOC_S_OUTPUT32: cmd = VIDIOC_S_OUTPUT; break;
+	case VIDIOC_PREPARE_BUF32: cmd = VIDIOC_PREPARE_BUF; break;
 	}
 
 	switch (cmd) {
@@ -775,6 +777,7 @@ static long do_video_ioctl(struct file *file, unsigned int cmd, unsigned long ar
 		compatible_arg = 0;
 		break;
 
+	case VIDIOC_PREPARE_BUF:
 	case VIDIOC_QUERYBUF:
 	case VIDIOC_QBUF:
 	case VIDIOC_DQBUF:
@@ -860,6 +863,7 @@ static long do_video_ioctl(struct file *file, unsigned int cmd, unsigned long ar
 		err = put_v4l2_format32(&karg.v2f, up);
 		break;
 
+	case VIDIOC_PREPARE_BUF:
 	case VIDIOC_QUERYBUF:
 	case VIDIOC_QBUF:
 	case VIDIOC_DQBUF:
@@ -959,6 +963,8 @@ long v4l2_compat_ioctl32(struct file *file, unsigned int cmd, unsigned long arg)
 	case VIDIOC_DQEVENT32:
 	case VIDIOC_SUBSCRIBE_EVENT:
 	case VIDIOC_UNSUBSCRIBE_EVENT:
+	case VIDIOC_CREATE_BUFS:
+	case VIDIOC_PREPARE_BUF32:
 		ret = do_video_ioctl(file, cmd, arg);
 		break;
 
diff --git a/drivers/media/video/v4l2-ioctl.c b/drivers/media/video/v4l2-ioctl.c
index 002ce13..3da87c0 100644
--- a/drivers/media/video/v4l2-ioctl.c
+++ b/drivers/media/video/v4l2-ioctl.c
@@ -260,6 +260,8 @@ static const char *v4l2_ioctls[] = {
 	[_IOC_NR(VIDIOC_DQEVENT)]	   = "VIDIOC_DQEVENT",
 	[_IOC_NR(VIDIOC_SUBSCRIBE_EVENT)]  = "VIDIOC_SUBSCRIBE_EVENT",
 	[_IOC_NR(VIDIOC_UNSUBSCRIBE_EVENT)] = "VIDIOC_UNSUBSCRIBE_EVENT",
+	[_IOC_NR(VIDIOC_CREATE_BUFS)]      = "VIDIOC_CREATE_BUFS",
+	[_IOC_NR(VIDIOC_PREPARE_BUF)]      = "VIDIOC_PREPARE_BUF",
 };
 #define V4L2_IOCTLS ARRAY_SIZE(v4l2_ioctls)
 
@@ -2216,6 +2218,30 @@ static long __video_do_ioctl(struct file *file,
 		dbgarg(cmd, "type=0x%8.8x", sub->type);
 		break;
 	}
+	case VIDIOC_CREATE_BUFS:
+	{
+		struct v4l2_create_buffers *create = arg;
+
+		if (!ops->vidioc_create_bufs)
+			break;
+
+		ret = ops->vidioc_create_bufs(file, fh, create);
+
+		dbgarg(cmd, "count=%u @ %u\n", create->count, create->index);
+		break;
+	}
+	case VIDIOC_PREPARE_BUF:
+	{
+		struct v4l2_buffer *b = arg;
+
+		if (!ops->vidioc_prepare_buf)
+			break;
+
+		ret = ops->vidioc_prepare_buf(file, fh, b);
+
+		dbgarg(cmd, "index=%d", b->index);
+		break;
+	}
 	default:
 	{
 		bool valid_prio = true;
diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
index fca24cc..3cd0cb3 100644
--- a/include/linux/videodev2.h
+++ b/include/linux/videodev2.h
@@ -653,6 +653,9 @@ struct v4l2_buffer {
 #define V4L2_BUF_FLAG_ERROR	0x0040
 #define V4L2_BUF_FLAG_TIMECODE	0x0100	/* timecode field is valid */
 #define V4L2_BUF_FLAG_INPUT     0x0200  /* input field is valid */
+/* Cache handling flags */
+#define V4L2_BUF_FLAG_NO_CACHE_INVALIDATE	0x0400
+#define V4L2_BUF_FLAG_NO_CACHE_CLEAN		0x0800
 
 /*
  *	O V E R L A Y   P R E V I E W
@@ -2092,6 +2095,18 @@ struct v4l2_dbg_chip_ident {
 	__u32 revision;    /* chip revision, chip specific */
 } __attribute__ ((packed));
 
+/* VIDIOC_CREATE_BUFS */
+struct v4l2_create_buffers {
+	__u32	index;	/* output: buffers index...index + count - 1 have been created */
+	__u32	count;
+	__u32	type;
+	__u32	memory;
+	__u32	fourcc;
+	__u32	num_planes;
+	__u32	sizes[VIDEO_MAX_PLANES];
+	__u32	reserved[18];
+};
+
 /*
  *	I O C T L   C O D E S   F O R   V I D E O   D E V I C E S
  *
@@ -2182,6 +2197,9 @@ struct v4l2_dbg_chip_ident {
 #define	VIDIOC_SUBSCRIBE_EVENT	 _IOW('V', 90, struct v4l2_event_subscription)
 #define	VIDIOC_UNSUBSCRIBE_EVENT _IOW('V', 91, struct v4l2_event_subscription)
 
+#define VIDIOC_CREATE_BUFS	_IOWR('V', 92, struct v4l2_create_buffers)
+#define VIDIOC_PREPARE_BUF	 _IOW('V', 93, struct v4l2_buffer)
+
 /* Reminder: when adding new ioctls please add support for them to
    drivers/media/video/v4l2-compat-ioctl32.c as well! */
 
diff --git a/include/media/v4l2-ioctl.h b/include/media/v4l2-ioctl.h
index dd9f1e7..4d1c74a 100644
--- a/include/media/v4l2-ioctl.h
+++ b/include/media/v4l2-ioctl.h
@@ -122,6 +122,8 @@ struct v4l2_ioctl_ops {
 	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_create_bufs)(struct file *file, void *fh, struct v4l2_create_buffers *b);
+	int (*vidioc_prepare_buf)(struct file *file, void *fh, struct v4l2_buffer *b);
 
 	int (*vidioc_overlay) (struct file *file, void *fh, unsigned int i);
 	int (*vidioc_g_fbuf)   (struct file *file, void *fh,
-- 
1.7.2.5