1 files changed, 4 insertions, 0 deletions

diff --git a/include/linux/mailbox_controller.h b/include/linux/mailbox_controller.h
index 9b0b21207345..4994a438444c 100644
--- a/include/linux/mailbox_controller.h
+++ b/include/linux/mailbox_controller.h
@@ -24,6 +24,9 @@ struct mbox_chan;
  *              transmission of data is reported by the controller via
  *              mbox_chan_txdone (if it has some TX ACK irq). It must not
  *              sleep.
+ * @flush:      Called when a client requests transmissions to be blocking but
+ *              the context doesn't allow sleeping. Typically the controller
+ *              will implement a busy loop waiting for the data to flush out.
  * @startup:    Called when a client requests the chan. The controller
  *              could ask clients for additional parameters of communication
  *              to be provided via client's chan_data. This call may
@@ -46,6 +49,7 @@ struct mbox_chan;
  */
 struct mbox_chan_ops {
         int (*send_data)(struct mbox_chan *chan, void *data);
+        int (*flush)(struct mbox_chan *chan, unsigned long timeout);
         int (*startup)(struct mbox_chan *chan);
         void (*shutdown)(struct mbox_chan *chan);
         bool (*last_tx_done)(struct mbox_chan *chan);