For each V4L2 device node create a media_dev attribute in /sys
which contains the media device major and minor number.
It is not created if the CONFIG_MEDIA_CONTROLLER is not
defined or if there is no associated media device.
This makes it possible for applications like v4l2-compliance
to find the associated media controller of a V4L2 device node.
Signed-off-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
---
drivers/media/v4l2-core/v4l2-dev.c | 49 +++++++++++++++++++++++++++++-
1 file changed, 48 insertions(+), 1 deletion(-)
diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c
index b6a72d297775..7a38176259ad 100644
--- a/drivers/media/v4l2-core/v4l2-dev.c
+++ b/drivers/media/v4l2-core/v4l2-dev.c
@@ -87,13 +87,60 @@ static ssize_t name_show(struct device *cd,
}
static DEVICE_ATTR_RO(name);
+#if defined(CONFIG_MEDIA_CONTROLLER)
+static ssize_t media_dev_show(struct device *cd,
+ struct device_attribute *attr, char *buf)
+{
+ struct video_device *vdev = to_video_device(cd);
+ struct v4l2_device *v4l2_dev = vdev->v4l2_dev;
+ dev_t devt = 0;
+
+ buf[0] = '\0';
+ if (v4l2_dev)
+ devt = media_device_devt(v4l2_dev->mdev);
+ if (!devt)
+ return 0;
+ return sprintf(buf, "%u:%u\n", MAJOR(devt), MINOR(devt));
+}
+
+static DEVICE_ATTR_RO(media_dev);
+#endif
+
+static umode_t video_device_attr_is_visible(struct kobject *kobj,
+ struct attribute *attr, int n)
+{
+ struct video_device *vdev = to_video_device(kobj_to_dev(kobj));
+
+#if defined(CONFIG_MEDIA_CONTROLLER)
+ if (attr == &dev_attr_media_dev.attr) {
+ struct v4l2_device *v4l2_dev = vdev->v4l2_dev;
+
+ if (!v4l2_dev->mdev)
+ return 0;
+ }
+#endif
+ return attr->mode;
+}
+
static struct attribute *video_device_attrs[] = {
&dev_attr_name.attr,
&dev_attr_dev_debug.attr,
&dev_attr_index.attr,
+#if defined(CONFIG_MEDIA_CONTROLLER)
+ &dev_attr_media_dev.attr,
+#endif
NULL,
};
-ATTRIBUTE_GROUPS(video_device);
+
+static const struct attribute_group video_device_group = {
+ .is_visible = video_device_attr_is_visible,
+ .attrs = video_device_attrs,
+};
+
+static const struct attribute_group *video_device_groups[] = {
+ &video_device_group,
+ NULL
+};
/*
* Active devices
--
2.29.2
