Bluetooth: controller: Issue Data Buffer Overflow event

Whenever the HCI ACL flow control is violated by the Host, a Data Buffer
Overflow event is now issued by the Controller (if enabled) to notify
the Host of the buffer overrun.

Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>

include/bluetooth/hci.h

@@ -1438,6 +1438,15 @@ struct bt_hci_evt_link_key_notify {
 	u8_t      key_type;
 } __packed;
 
+/* Overflow link types */
+#define BT_OVERFLOW_LINK_SYNCH                  0x00
+#define BT_OVERFLOW_LINK_ACL                    0x01
+
+#define BT_HCI_EVT_DATA_BUF_OVERFLOW            0x1a
+struct bt_hci_evt_data_buf_overflow {
+	u8_t      link_type;
+} __packed;
+
 #define BT_HCI_EVT_INQUIRY_RESULT_WITH_RSSI     0x22
 struct bt_hci_evt_inquiry_result_with_rssi {
 	bt_addr_t addr;

subsys/bluetooth/controller/hci/hci.c

@@ -1811,6 +1811,21 @@ static int vendor_cmd_handle(u16_t ocf, struct net_buf *cmd,
 	return 0;
 }
 
+static void data_buf_overflow(struct net_buf **buf)
+{
+	struct bt_hci_evt_data_buf_overflow *ep;
+
+	if (!(event_mask & BT_EVT_MASK_DATA_BUFFER_OVERFLOW)) {
+		return;
+	}
+
+	*buf = bt_buf_get_rx(BT_BUF_EVT, K_FOREVER);
+	evt_create(*buf, BT_HCI_EVT_DATA_BUF_OVERFLOW, sizeof(*ep));
+	ep = net_buf_add(*buf, sizeof(*ep));
+
+	ep->link_type = BT_OVERFLOW_LINK_ACL;
+}
+
 struct net_buf *hci_cmd_handle(struct net_buf *cmd)
 {
 	struct bt_hci_evt_cc_status *ccst;
@@ -1869,7 +1884,7 @@ struct net_buf *hci_cmd_handle(struct net_buf *cmd)
 	return evt;
 }
 
-int hci_acl_handle(struct net_buf *buf)
+int hci_acl_handle(struct net_buf *buf, struct net_buf **evt)
 {
 	struct radio_pdu_node_tx *radio_pdu_node_tx;
 	struct bt_hci_acl_hdr *acl;
@@ -1878,6 +1893,8 @@ int hci_acl_handle(struct net_buf *buf)
 	u8_t flags;
 	u16_t len;
 
+	*evt = NULL;
+
 	if (buf->len < sizeof(*acl)) {
 		BT_ERR("No HCI ACL header");
 		return -EINVAL;
@@ -1900,6 +1917,7 @@ int hci_acl_handle(struct net_buf *buf)
 	radio_pdu_node_tx = radio_tx_mem_acquire();
 	if (!radio_pdu_node_tx) {
 		BT_ERR("Tx Buffer Overflow");
+		data_buf_overflow(evt);
 		return -ENOBUFS;
 	}
 

subsys/bluetooth/controller/hci/hci_driver.c

@@ -347,6 +347,22 @@ static int cmd_handle(struct net_buf *buf)
 	return 0;
 }
 
+#if defined(CONFIG_BT_CONN)
+static int acl_handle(struct net_buf *buf)
+{
+	struct net_buf *evt;
+	int err;
+
+	err = hci_acl_handle(buf, &evt);
+	if (evt) {
+		BT_DBG("Replying with event of %u bytes", evt->len);
+		bt_recv_prio(evt);
+	}
+
+	return err;
+}
+#endif /* CONFIG_BT_CONN */
+
 static int hci_driver_send(struct net_buf *buf)
 {
 	u8_t type;
@@ -363,9 +379,9 @@ static int hci_driver_send(struct net_buf *buf)
 	switch (type) {
 #if defined(CONFIG_BT_CONN)
 	case BT_BUF_ACL_OUT:
-		err = hci_acl_handle(buf);
+		err = acl_handle(buf);
 		break;
-#endif
+#endif /* CONFIG_BT_CONN */
 	case BT_BUF_CMD:
 		err = cmd_handle(buf);
 		break;

subsys/bluetooth/controller/hci/hci_internal.h

@@ -39,7 +39,7 @@ struct net_buf *hci_cmd_handle(struct net_buf *cmd);
 void hci_evt_encode(struct radio_pdu_node_rx *node_rx, struct net_buf *buf);
 s8_t hci_get_class(struct radio_pdu_node_rx *node_rx);
 #if defined(CONFIG_BT_CONN)
-int hci_acl_handle(struct net_buf *acl);
+int hci_acl_handle(struct net_buf *acl, struct net_buf **evt);
 void hci_acl_encode(struct radio_pdu_node_rx *node_rx, struct net_buf *buf);
 void hci_num_cmplt_encode(struct net_buf *buf, u16_t handle, u8_t num);
 #endif