+static int can_validate(struct nlattr *tb[], struct nlattr *data[])
+{
+ bool is_can_fd = false;
+
+ /* Make sure that valid CAN FD configurations always consist of
+ * - nominal/arbitration bittiming
+ * - data bittiming
+ * - control mode with CAN_CTRLMODE_FD set
+ */
+
+ if (data[IFLA_CAN_CTRLMODE]) {
+ struct can_ctrlmode *cm = nla_data(data[IFLA_CAN_CTRLMODE]);
+
+ is_can_fd = cm->flags & cm->mask & CAN_CTRLMODE_FD;
+ }
+
+ if (is_can_fd) {
+ if (!data[IFLA_CAN_BITTIMING] || !data[IFLA_CAN_DATA_BITTIMING])
+ return -EOPNOTSUPP;
+ }
+
+ if (data[IFLA_CAN_DATA_BITTIMING]) {
+ if (!is_can_fd || !data[IFLA_CAN_BITTIMING])
+ return -EOPNOTSUPP;
+ }
+
+ return 0;
+}
+