FROMLIST: v4l: async: Add a convenience function for registering sensors

Add a convenience function for parsing firmware for information on related
devices using v4l2_async_notifier_parse_fwnode_sensor_common() registering
the notifier and finally the async sub-device itself.

This should be useful for sensor drivers that do not have device specific
requirements related to firmware information parsing or the async
framework.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
(cherry picked from commit dd202f9d5346cacd785a482952f54b205eafcc64)
https://git.linuxtv.org/sailus/media_tree.git/log/?h=010f7f4393fd
http://www.spinics.net/lists/linux-media/msg122688.html
Signed-off-by: Marc Herbert <marc.herbert@intel.com>

Conflicts:
	include/media/v4l2-subdev.h
(convert to older documentation style)

BUG=b:64133998
TEST=media device topology shows subdevs registered successfully
TEST=no camera regression

Change-Id: Ia4af50d7204173d17d04faf9575f6605a1400e46
Reviewed-on: https://chromium-review.googlesource.com/693700
Commit-Ready: Tomasz Figa <tfiga@chromium.org>
Tested-by: Hyungwoo Yang <hyungwoo.yang@intel.com>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Signed-off-by: Jacob Chen <jacob2.chen@rock-chips.com>

Author: Sakari Ailus

drivers/media/v4l2-core/v4l2-async.c

@@ -584,6 +584,11 @@ void v4l2_async_unregister_subdev(struct v4l2_subdev *sd)
 {
 	struct v4l2_async_notifier *notifier = sd->notifier;
 
+	if (sd->subdev_notifier)
+		v4l2_async_notifier_unregister(sd->subdev_notifier);
+	v4l2_async_notifier_cleanup(sd->subdev_notifier);
+	kfree(sd->subdev_notifier);
+
 	if (!sd->asd) {
 		if (!list_empty(&sd->async_list))
 			v4l2_async_cleanup(sd);

drivers/media/v4l2-core/v4l2-fwnode.c

@@ -29,6 +29,7 @@
 
 #include <media/v4l2-async.h>
 #include <media/v4l2-fwnode.h>
+#include <media/v4l2-subdev.h>
 
 static int v4l2_fwnode_endpoint_parse_csi_bus(struct fwnode_handle *fwnode,
 					      struct v4l2_fwnode_endpoint *vep)
@@ -765,6 +766,46 @@ int v4l2_async_notifier_parse_fwnode_sensor_common(
 }
 EXPORT_SYMBOL_GPL(v4l2_async_notifier_parse_fwnode_sensor_common);
 
+int v4l2_async_register_subdev_sensor_common(struct v4l2_subdev *sd)
+{
+	struct v4l2_async_notifier *notifier;
+	int ret;
+
+	if (WARN_ON(!sd->dev))
+		return -ENODEV;
+
+	notifier = kzalloc(sizeof(*notifier), GFP_KERNEL);
+	if (!notifier)
+		return -ENOMEM;
+
+	ret = v4l2_async_notifier_parse_fwnode_sensor_common(sd->dev,
+							     notifier);
+	if (ret < 0)
+		goto out_cleanup;
+
+	ret = v4l2_async_subdev_notifier_register(sd, notifier);
+	if (ret < 0)
+		goto out_cleanup;
+
+	ret = v4l2_async_register_subdev(sd);
+	if (ret < 0)
+		goto out_unregister;
+
+	sd->subdev_notifier = notifier;
+
+	return 0;
+
+out_unregister:
+	v4l2_async_notifier_unregister(notifier);
+
+out_cleanup:
+	v4l2_async_notifier_cleanup(notifier);
+	kfree(notifier);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(v4l2_async_register_subdev_sensor_common);
+
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Sakari Ailus <sakari.ailus@linux.intel.com>");
 MODULE_AUTHOR("Sylwester Nawrocki <s.nawrocki@samsung.com>");

include/media/v4l2-async.h

@@ -172,6 +172,28 @@ void v4l2_async_notifier_cleanup(struct v4l2_async_notifier *notifier);
  */
 int v4l2_async_register_subdev(struct v4l2_subdev *sd);
 
+/**
+ * v4l2_async_register_subdev_sensor_common - registers a sensor sub-device to
+ *					      the asynchronous sub-device
+ *					      framework and parse set up common
+ *					      sensor related devices
+ *
+ * @sd: pointer to struct &v4l2_subdev
+ *
+ * This function is just like v4l2_async_register_subdev() with the exception
+ * that calling it will also parse firmware interfaces for remote references
+ * using v4l2_async_notifier_parse_fwnode_sensor_common() and registers the
+ * async sub-devices. The sub-device is similarly unregistered by calling
+ * v4l2_async_unregister_subdev().
+ *
+ * While registered, the subdev module is marked as in-use.
+ *
+ * An error is returned if the module is no longer loaded on any attempts
+ * to register it.
+ */
+int __must_check v4l2_async_register_subdev_sensor_common(
+	struct v4l2_subdev *sd);
+
 /**
  * v4l2_async_unregister_subdev - unregisters a sub-device to the asynchronous
  * 	subdevice framework

include/media/v4l2-subdev.h

@@ -750,6 +750,9 @@ struct v4l2_subdev {
 	/* Pointer to the managing notifier. */
 	struct v4l2_async_notifier *notifier;
 	/* common part of subdevice platform data */
+	struct v4l2_async_notifier *subdev_notifier;
+	/* A sub-device notifier implicitly registered for the sub-device
+	   using v4l2_device_register_sensor_subdev(). */
 	struct v4l2_subdev_platform_data *pdata;
 };