linux-kernel - [PATCH 1/1] v4l: Add camera voice coil lens control class, current control

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Date:	Sun, 12 Jun 2016 23:41:50 +0300
From:	Sakari Ailus <sakari.ailus@...ux.intel.com>
To:	pavel@....cz
Cc:	ivo.g.dimitrov.75@...il.com, pali.rohar@...il.com, sre@...nel.org,
	linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
	hverkuil@...all.nl, laurent.pinchart@...asonboard.com,
	Sakari Ailus <sakari.ailus@....fi>
Subject: [PATCH 1/1] v4l: Add camera voice coil lens control class, current control

From: Sakari Ailus <sakari.ailus@....fi>

Add a V4L2 control class for voice coil lens driver devices.  These are
simple devices that are used to move a camera lens from its resting
position.

Signed-off-by: Sakari Ailus <sakari.ailus@...ux.intel.com>
---
Hi Pavel,

I also don't think the FOCUS_ABSOLUTE controls is a really good one for
the voice coil lens current. I expect more voice coil lens controls
(linear vs. PWM mode, ringing compensation...) to be needed so I think
it's worth a new class.

Cc others, too...

Kind regards,
Sakari

 Documentation/DocBook/media/v4l/controls.xml | 55 +++++++++++++++++++++++++++-
 include/uapi/linux/v4l2-controls.h           |  7 ++++
 2 files changed, 61 insertions(+), 1 deletion(-)

diff --git a/Documentation/DocBook/media/v4l/controls.xml b/Documentation/DocBook/media/v4l/controls.xml
index e2e5484..aa7169c 100644
--- a/Documentation/DocBook/media/v4l/controls.xml
+++ b/Documentation/DocBook/media/v4l/controls.xml
@@ -5502,4 +5502,57 @@ receiving given frequency when that control is set. This is a read-only control.
         </tgroup>
       </table>
     </section>
-</section>
+
+    <section id="voice-coil-controls">
+      <title>Voice Coil Control Reference</title>
+
+      <para>The Voice Coil class controls are used to control voice
+      coil lens devices. These are very simple devices that consist of
+      a voice coil, a spring and a lens. The current applied on a
+      voice coil is used to move the lens away from the resting
+      position which typically is (close to) infinity.</para>
+
+      <table pgwide="1" frame="none" id="voice-coil-control-id">
+      <title>Voice Coil Control IDs</title>
+
+      <tgroup cols="4">
+        <colspec colname="c1" colwidth="1*" />
+        <colspec colname="c2" colwidth="6*" />
+        <colspec colname="c3" colwidth="2*" />
+        <colspec colname="c4" colwidth="6*" />
+        <spanspec namest="c1" nameend="c2" spanname="id" />
+        <spanspec namest="c2" nameend="c4" spanname="descr" />
+        <thead>
+          <row>
+            <entry spanname="id" align="left">ID</entry>
+            <entry align="left">Type</entry>
+          </row><row rowsep="1"><entry spanname="descr" align="left">Description</entry>
+          </row>
+        </thead>
+        <tbody valign="top">
+          <row><entry></entry></row>
+          <row>
+            <entry spanname="id"><constant>V4L2_CID_VOICE_COIL_CLASS</constant>&nbsp;</entry>
+            <entry>class</entry>
+          </row><row><entry spanname="descr">The Voice Coil class
+descriptor. Calling &VIDIOC-QUERYCTRL; for this control will return a
+description of this control class.</entry>
+          </row>
+          <row>
+            <entry spanname="id"><constant>V4L2_CID_VOICE_COIL_CURRENT</constant>&nbsp;</entry>
+            <entry>integer</entry>
+          </row><row><entry spanname="descr">Current applied on a
+          voice coil. The more current is applied, the more is the
+          position of the lens moved from its resting position. Do
+          note that there may be a ringing effect; the lens will
+          oscillate after changing the current applied unless the
+          device implements ringing compensation.
+          </entry>
+          </row>
+        </tbody>
+      </tgroup>
+      </table>
+
+      </section>
+
+  </section>
diff --git a/include/uapi/linux/v4l2-controls.h b/include/uapi/linux/v4l2-controls.h
index b6a357a..c6b1261 100644
--- a/include/uapi/linux/v4l2-controls.h
+++ b/include/uapi/linux/v4l2-controls.h
@@ -62,6 +62,7 @@
 #define V4L2_CTRL_CLASS_FM_RX		0x00a10000	/* FM Receiver controls */
 #define V4L2_CTRL_CLASS_RF_TUNER	0x00a20000	/* RF tuner controls */
 #define V4L2_CTRL_CLASS_DETECT		0x00a30000	/* Detection controls */
+#define V4L2_CTRL_CLASS_VOICE_COIL	0x00a40000	/* Voice coil lens driver */
 
 /* User-class control IDs */
 
@@ -974,4 +975,10 @@ enum v4l2_detect_md_mode {
 #define V4L2_CID_DETECT_MD_THRESHOLD_GRID	(V4L2_CID_DETECT_CLASS_BASE + 3)
 #define V4L2_CID_DETECT_MD_REGION_GRID		(V4L2_CID_DETECT_CLASS_BASE + 4)
 
+/*  Voice coil lens driver control IDs defined by V4L2 */
+#define V4L2_CID_VOICE_COIL_CLASS_BASE		(V4L2_CTRL_CLASS_VOICE_COIL | 0x900)
+#define V4L2_CID_VOICE_COIL_CLASS		(V4L2_CTRL_CLASS_VOICE_COIL | 1)
+
+#define V4L2_CID_VOICE_COIL_CURRENT		(V4L2_CID_VOICE_COIL_CLASS_BASE + 1)
+
 #endif
-- 
2.1.4