mailbox: check ->last_tx_done for NULL in case of timer-based polling

It is allowed by code to register mailbox controller that sets txdone_poll
flag to request timer-based polling with missed ->last_tx_done() method.
If such thing happens and since presence of last_tx_done() is not checked
it will fail in hrtimer callback function txdone_hrtimer() when first
message will be transmitted.

This patch adds check for this method and logging of error on
registration of mailbox controller if it requested timer-based polling.

Signed-off-by: Alexey Klimov <alexey.klimov@arm.com>
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c
index 4671f8a12872..59b722177bf7 100644
--- a/drivers/mailbox/mailbox.c
+++ b/drivers/mailbox/mailbox.c
@@ -453,6 +453,12 @@ int mbox_controller_register(struct mbox_controller *mbox)
                 txdone = TXDONE_BY_ACK;
 
         if (txdone == TXDONE_BY_POLL) {
+
+                if (!mbox->ops->last_tx_done) {
+                        dev_err(mbox->dev, "last_tx_done method is absent\n");
+                        return -EINVAL;
+                }
+
                 hrtimer_init(&mbox->poll_hrt, CLOCK_MONOTONIC,
                              HRTIMER_MODE_REL);
                 mbox->poll_hrt.function = txdone_hrtimer;