[media] v4l2-subdev: add (un)register internal ops

Some subdevs need to call into the board code after they are registered
and have a valid struct v4l2_device pointer. The s_config op was abused
for this, but now that it is removed we need a cleaner way of solving this.

So this patch adds a struct with internal ops that the v4l2 core can call.

Currently only two ops exist: register and unregister. Subdevs can implement
these to call the board code and pass it the v4l2_device pointer, which the
board code can then use to get access to the struct that embeds the
v4l2_device.

It is expected that in the future open and close ops will also be added.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

2 files changed, 29 insertions, 2 deletions

diff --git a/drivers/media/video/v4l2-device.c b/drivers/media/video/v4l2-device.c
index 7fe6f92af480..b24f002ffa67 100644
--- a/drivers/media/video/v4l2-device.c
+++ b/drivers/media/video/v4l2-device.c
@@ -126,11 +126,19 @@ int v4l2_device_register_subdev(struct v4l2_device *v4l2_dev,
         WARN_ON(sd->v4l2_dev != NULL);
         if (!try_module_get(sd->owner))
                 return -ENODEV;
+        sd->v4l2_dev = v4l2_dev;
+        if (sd->internal_ops && sd->internal_ops->registered) {
+                err = sd->internal_ops->registered(sd);
+                if (err)
+                        return err;
+        }
         /* This just returns 0 if either of the two args is NULL */
         err = v4l2_ctrl_add_handler(v4l2_dev->ctrl_handler, sd->ctrl_handler);
-        if (err)
+        if (err) {
+                if (sd->internal_ops && sd->internal_ops->unregistered)
+                        sd->internal_ops->unregistered(sd);
                 return err;
-        sd->v4l2_dev = v4l2_dev;
+        }
         spin_lock(&v4l2_dev->lock);
         list_add_tail(&sd->list, &v4l2_dev->subdevs);
         spin_unlock(&v4l2_dev->lock);
@@ -146,6 +154,8 @@ void v4l2_device_unregister_subdev(struct v4l2_subdev *sd)
         spin_lock(&sd->v4l2_dev->lock);
         list_del(&sd->list);
         spin_unlock(&sd->v4l2_dev->lock);
+        if (sd->internal_ops && sd->internal_ops->unregistered)
+                sd->internal_ops->unregistered(sd);
         sd->v4l2_dev = NULL;
         module_put(sd->owner);
 }
diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
index 42fbe462031d..daf1e57d9b26 100644
--- a/include/media/v4l2-subdev.h
+++ b/include/media/v4l2-subdev.h
@@ -411,6 +411,21 @@ struct v4l2_subdev_ops {
         const struct v4l2_subdev_sensor_ops     *sensor;
 };
 
+/*
+ * Internal ops. Never call this from drivers, only the v4l2 framework can call
+ * these ops.
+ *
+ * registered: called when this subdev is registered. When called the v4l2_dev
+ *      field is set to the correct v4l2_device.
+ *
+ * unregistered: called when this subdev is unregistered. When called the
+ *      v4l2_dev field is still set to the correct v4l2_device.
+ */
+struct v4l2_subdev_internal_ops {
+        int (*registered)(struct v4l2_subdev *sd);
+        void (*unregistered)(struct v4l2_subdev *sd);
+};
+
 #define V4L2_SUBDEV_NAME_SIZE 32
 
 /* Set this flag if this subdev is a i2c device. */
@@ -427,6 +442,8 @@ struct v4l2_subdev {
         u32 flags;
         struct v4l2_device *v4l2_dev;
         const struct v4l2_subdev_ops *ops;
+        /* Never call these internal ops from within a driver! */
+        const struct v4l2_subdev_internal_ops *internal_ops;
         /* The control handler of this subdev. May be NULL. */
         struct v4l2_ctrl_handler *ctrl_handler;
         /* name must be unique */