mailbox: Support blocking transfers in atomic context
The mailbox framework supports blocking transfers via completions for
clients that can sleep. In order to support blocking transfers in cases
where the transmission is not permitted to sleep, add a new ->flush()
callback that controller drivers can implement to busy loop until the
transmission has been completed. A new mbox_flush() function can be
called by mailbox consumers in atomic context to make sure a transfer
has completed.
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
diff --git a/include/linux/mailbox_controller.h b/include/linux/mailbox_controller.h
index 9b0b212..4994a43 100644
--- a/include/linux/mailbox_controller.h
+++ b/include/linux/mailbox_controller.h
@@ -24,6 +24,9 @@
* 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_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);