mtd: ubi: populate ubi volume fwnode

Look for the 'volumes' subnode of an MTD partition attached to a UBI
device and attach matching child nodes to UBI volumes.
This allows UBI volumes to be referenced in device tree, e.g. for use
as NVMEM providers.
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Signed-off-by: Richard Weinberger <richard@nod.at>

drivers/mtd/ubi/vmt.c

@@ -124,6 +124,31 @@ static void vol_release(struct device *dev)
 	kfree(vol);
 }
 
+static struct fwnode_handle *find_volume_fwnode(struct ubi_volume *vol)
+{
+	struct fwnode_handle *fw_vols, *fw_vol;
+	const char *volname;
+	u32 volid;
+
+	fw_vols = device_get_named_child_node(vol->dev.parent->parent, "volumes");
+	if (!fw_vols)
+		return NULL;
+
+	fwnode_for_each_child_node(fw_vols, fw_vol) {
+		if (!fwnode_property_read_string(fw_vol, "volname", &volname) &&
+		    strncmp(volname, vol->name, vol->name_len))
+			continue;
+
+		if (!fwnode_property_read_u32(fw_vol, "volid", &volid) &&
+		    vol->vol_id != volid)
+			continue;
+
+		return fw_vol;
+	}
+
+	return NULL;
+}
+
 /**
  * ubi_create_volume - create volume.
  * @ubi: UBI device description object
@@ -223,6 +248,7 @@ int ubi_create_volume(struct ubi_device *ubi, struct ubi_mkvol_req *req)
 	vol->name_len  = req->name_len;
 	memcpy(vol->name, req->name, vol->name_len);
 	vol->ubi = ubi;
+	device_set_node(&vol->dev, find_volume_fwnode(vol));
 
 	/*
 	 * Finish all pending erases because there may be some LEBs belonging
@@ -614,6 +640,7 @@ int ubi_add_volume(struct ubi_device *ubi, struct ubi_volume *vol)
 	vol->dev.class = &ubi_class;
 	vol->dev.groups = volume_dev_groups;
 	dev_set_name(&vol->dev, "%s_%d", ubi->ubi_name, vol->vol_id);
+	device_set_node(&vol->dev, find_volume_fwnode(vol));
 	err = device_register(&vol->dev);
 	if (err) {
 		cdev_del(&vol->cdev);