Add a helper function for use by the DVB and V4L2 core frameworks
that safely returns the major and minor numbers of the media
device node, or 0 if the device node is not registered.
Signed-off-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
---
drivers/media/mc/mc-device.c | 16 ++++++++++++++++
include/media/media-device.h | 10 ++++++++++
2 files changed, 26 insertions(+)
diff --git a/drivers/media/mc/mc-device.c b/drivers/media/mc/mc-device.c
index 9e56d2ad6b94..2207f1b01456 100644
--- a/drivers/media/mc/mc-device.c
+++ b/drivers/media/mc/mc-device.c
@@ -850,6 +850,22 @@ void media_device_unregister(struct media_device *mdev)
}
EXPORT_SYMBOL_GPL(media_device_unregister);
+dev_t media_device_devt(struct media_device *mdev)
+{
+ dev_t devt = 0;
+
+ if (!mdev)
+ return 0;
+
+ mutex_lock(&mdev->graph_mutex);
+ /* Check if mdev is registered */
+ if (media_devnode_is_registered(mdev->devnode))
+ devt = mdev->devnode->dev.devt;
+ mutex_unlock(&mdev->graph_mutex);
+ return devt;
+}
+EXPORT_SYMBOL_GPL(media_device_devt);
+
#if IS_ENABLED(CONFIG_PCI)
void media_device_pci_init(struct media_device *mdev,
struct pci_dev *pci_dev,
diff --git a/include/media/media-device.h b/include/media/media-device.h
index 1345e6da688a..af089b1c55ef 100644
--- a/include/media/media-device.h
+++ b/include/media/media-device.h
@@ -300,6 +300,16 @@ int __must_check __media_device_register(struct media_device *mdev,
*/
void media_device_unregister(struct media_device *mdev);
+/**
+ * media_device_devt() - return media device major/minor numbers
+ *
+ * @mdev: pointer to struct &media_device
+ *
+ * Returns 0 if the media device node is not registered, otherwise
+ * it will return the major/minor number of the media device node.
+ */
+dev_t media_device_devt(struct media_device *mdev);
+
/**
* media_device_register_entity() - registers a media entity inside a
* previously registered media device.
--
2.29.2
