Add support for resetting pan and tilt on Logitech webcams.

extensions/browser/api/webcam_private/webcam_private_api_chromeos.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "extensions/browser/api/webcam_private/webcam_private_api.h"
 
 #include <fcntl.h>
+#include <linux/uvcvideo.h>
 #include <linux/videodev2.h>
 #include <stdio.h>
 #include <sys/ioctl.h>
 #include <unistd.h>
 
 #include "base/files/scoped_file.h"
 #include "base/posix/eintr_wrapper.h"
 #include "content/public/browser/browser_context.h"
 #include "content/public/browser/media_device_id.h"
 #include "content/public/browser/resource_context.h"
 #include "content/public/common/media_stream_request.h"
 #include "extensions/common/api/webcam_private.h"
 
 #define V4L2_CID_PAN_SPEED (V4L2_CID_CAMERA_CLASS_BASE+32)
 #define V4L2_CID_TILT_SPEED (V4L2_CID_CAMERA_CLASS_BASE+33)
+#define V4L2_CID_PANTILT_CMD (V4L2_CID_CAMERA_CLASS_BASE+34)
+
+/*

[tommi (sloooow) - chröme, 2015/01/13 16:37:39]

use // type comments

[Zachary Kuznia, 2015/01/13 20:54:59]

Done.

+ * GUID of the Extension Unit for Logitech CC3300e motor control:
+ * {212de5ff-3080-2c4e-82d9-f587d00540bd}
+ */
+#define UVC_GUID_LOGITECH_CC3000E_MOTORS          \
+ {0x21, 0x2d, 0xe5, 0xff, 0x30, 0x80, 0x2c, 0x4e, \
+  0x82, 0xd9, 0xf5, 0x87, 0xd0, 0x05, 0x40, 0xbd}
+
+#define LOGITECH_MOTORCONTROL_PANTILT_CMD 2
 
 namespace webcam_private = extensions::core_api::webcam_private;
 
 namespace content {
 class BrowserContext;
 }  // namespace content
 
 namespace {
+const int kLogitechMenuIndexGoHome = 2;
+
+const uvc_menu_info kLogitechCmdMenu[3] = {

[tommi (sloooow) - chröme, 2015/01/13 16:37:39]

since you're using sizeof to derive this size, do you need to specify it here? 
I.e. is it OK to do:
const uvc_menu_info kLogitechCmdMenu[] = {
...

[Zachary Kuznia, 2015/01/13 20:54:59]

Done.

+  {1, "Set Preset"}, {2, "Get Preset"}, {3, "Go Home"}
+};
+
+const uvc_xu_control_mapping kLogitechCmdMapping = {
+  V4L2_CID_PANTILT_CMD,
+  "Pan/Tilt Go",
+  UVC_GUID_LOGITECH_CC3000E_MOTORS,
+  LOGITECH_MOTORCONTROL_PANTILT_CMD,
+  8,
+  0,
+  V4L2_CTRL_TYPE_MENU,
+  UVC_CTRL_DATA_TYPE_ENUM,
+  const_cast<uvc_menu_info*>(kLogitechCmdMenu),

[tommi (sloooow) - chröme, 2015/01/13 16:37:39]

nit: &kLogitechCmdMenu[0]

[Zachary Kuznia, 2015/01/13 20:54:59]

Done.

+  sizeof(kLogitechCmdMenu)/sizeof(struct uvc_menu_info),

[tommi (sloooow) - chröme, 2015/01/13 16:37:40]

arraysize()

[Zachary Kuznia, 2015/01/13 20:54:59]

Done.

+};
 
 base::ScopedFD OpenWebcam(const std::string& extension_id,
                           content::BrowserContext* browser_context,
                           const std::string& webcam_id) {
   GURL security_origin =
       extensions::Extension::GetBaseURLFromExtensionId(extension_id);
 
   std::string device_id;
   bool success = content::GetMediaDeviceIDForHMAC(
       content::MEDIA_DEVICE_VIDEO_CAPTURE,
@@ skipping 16 matching lines @@
 bool GetWebcamParameter(int fd, uint32_t control_id, int* value) {
   struct v4l2_control v4l2_ctrl = {control_id};
 
   if (HANDLE_EINTR(ioctl(fd, VIDIOC_G_CTRL, &v4l2_ctrl)))
     return false;
 
   *value = v4l2_ctrl.value;
   return true;
 }
 
+bool EnsureLogitechCommandsMapped(int fd) {
+  int res = ioctl(fd, UVCIOC_CTRL_MAP, &kLogitechCmdMapping);
+  if (res < 0) {

[tommi (sloooow) - chröme, 2015/01/13 16:37:40]

nit:

return res < 0 || errno == EEXIST;

[Zachary Kuznia, 2015/01/13 20:54:59]

Done.

+    if (errno == EEXIST) {
+      // Already mapped, success.
+      return true;
+    } else {
+      // Cannot map, camera doesn't support this command.
+      return false;
+    }
+  } else {
+    return true;
+  }
+}
+
 const char kUnknownWebcam[] = "Unknown webcam id";
 }  // namespace
 
 namespace extensions {
 
 WebcamPrivateSetFunction::WebcamPrivateSetFunction() {
 }
 
 WebcamPrivateSetFunction::~WebcamPrivateSetFunction() {
 }
@@ skipping 118 matching lines @@
       webcam_private::Reset::Params::Create(*args_));
   EXTENSION_FUNCTION_VALIDATE(params.get());
 
   base::ScopedFD fd =
       OpenWebcam(extension_id(), browser_context(), params->webcam_id);
   if (!fd.is_valid()) {
     SetError(kUnknownWebcam);
     return false;
   }
 
+  if (params->config.pan || params->config.tilt) {
+    if (EnsureLogitechCommandsMapped(fd.get())) {
+      SetWebcamParameter(fd.get(), V4L2_CID_PANTILT_CMD,
+                         kLogitechMenuIndexGoHome);
+    }
+  }
+
   if (params->config.pan) {
     struct v4l2_control v4l2_ctrl = {V4L2_CID_PAN_RESET};
     HANDLE_EINTR(ioctl(fd.get(), VIDIOC_S_CTRL, &v4l2_ctrl));
   }
 
   if (params->config.tilt) {
     struct v4l2_control v4l2_ctrl = {V4L2_CID_TILT_RESET};
     HANDLE_EINTR(ioctl(fd.get(), VIDIOC_S_CTRL, &v4l2_ctrl));
   }
 
   if (params->config.zoom) {
     const int kDefaultZoom = 100;
     SetWebcamParameter(fd.get(), V4L2_CID_ZOOM_ABSOLUTE, kDefaultZoom);
   }
 
   return true;
 }
 
 }  // namespace extensions