@@ -314,6 +314,30 @@ controlled through GPIO pins. This distinction is only relevant when setting
up the device, but once the subdev is registered it is completely transparent.
+V4L2 sub-device userspace API
+-----------------------------
+
+Beside exposing a kernel API through the v4l2_subdev_ops structure, V4L2
+sub-devices can also be controlled directly by userspace applications.
+
+When a sub-device is registered, a device node named subdevX is created in /dev.
+The device node handles a subset of the V4L2 API.
+
+VIDIOC_QUERYCTRL
+VIDIOC_QUERYMENU
+VIDIOC_G_CTRL
+VIDIOC_S_CTRL
+VIDIOC_G_EXT_CTRLS
+VIDIOC_S_EXT_CTRLS
+VIDIOC_TRY_EXT_CTRLS
+
+ The controls ioctls are identical to the ones defined in V4L2. They
+ behave identically, with the only exception that they deal only with
+ controls implemented in the sub-device. Depending on the driver, those
+ controls can be also be accessed through one (or several) V4L2 device
+ nodes.
+
+
I2C sub-device drivers
----------------------
@@ -43,7 +43,31 @@ static int subdev_close(struct file *file)
static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg)
{
+ struct video_device *vdev = video_devdata(file);
+ struct v4l2_subdev *sd = vdev_to_v4l2_subdev(vdev);
+
switch (cmd) {
+ case VIDIOC_QUERYCTRL:
+ return v4l2_subdev_call(sd, core, queryctrl, arg);
+
+ case VIDIOC_QUERYMENU:
+ return v4l2_subdev_call(sd, core, querymenu, arg);
+
+ case VIDIOC_G_CTRL:
+ return v4l2_subdev_call(sd, core, g_ctrl, arg);
+
+ case VIDIOC_S_CTRL:
+ return v4l2_subdev_call(sd, core, s_ctrl, arg);
+
+ case VIDIOC_G_EXT_CTRLS:
+ return v4l2_subdev_call(sd, core, g_ext_ctrls, arg);
+
+ case VIDIOC_S_EXT_CTRLS:
+ return v4l2_subdev_call(sd, core, s_ext_ctrls, arg);
+
+ case VIDIOC_TRY_EXT_CTRLS:
+ return v4l2_subdev_call(sd, core, try_ext_ctrls, arg);
+
default:
return -ENOIOCTLCMD;
}