LE: Add notification sent and congestion callbacks (1/4)

This change introduces two new callbacks for applications to better
handle LE notification flow control and transport congestion. The
notification callback is invoked when the remote platform confirms an
indication or when a local notification has been passed to the
controller. No new notifications should be sent until a callback is
received.

Congestion callbacks are triggered when a GATT operation cannot be sent
to the local Bluetooth controller. Repeatedly calling
writeCharacteristic() for example will eventually trigger a congestion
callback. Applications cannot send additional data until a further
callback is received, indicating that the congestion has cleared up.

Change-Id: I613cbf968770921f853a407888bb8308849039f3

1 files changed, 15 insertions, 0 deletions

diff --git a/include/hardware/bt_gatt_server.h b/include/hardware/bt_gatt_server.h
index 32f8ef6..2b1de27 100644
--- a/include/hardware/bt_gatt_server.h
+++ b/include/hardware/bt_gatt_server.h
@@ -104,6 +104,19 @@ typedef void (*request_exec_write_callback)(int conn_id, int trans_id,
  */
 typedef void (*response_confirmation_callback)(int status, int handle);
 
+/**
+ * Callback confirming that a notification or indication has been sent
+ * to a remote device.
+ */
+typedef void (*indication_sent_callback)(int conn_id, int status);
+
+/**
+ * Callback notifying an application that a remote device connection is currently congested
+ * and cannot receive any more data. An application should avoid sending more data until
+ * a further callback is received indicating the congestion status has been cleared.
+ */
+typedef void (*congestion_callback)(int conn_id, bool congested);
+
 typedef struct {
     register_server_callback        register_server_cb;
     connection_callback             connection_cb;
@@ -118,6 +131,8 @@ typedef struct {
     request_write_callback          request_write_cb;
     request_exec_write_callback     request_exec_write_cb;
     response_confirmation_callback  response_confirmation_cb;
+    indication_sent_callback        indication_sent_cb;
+    congestion_callback             congestion_cb;
 } btgatt_server_callbacks_t;
 
 /** Represents the standard BT-GATT server interface. */