Bluetooth: Add hci_conn_lookup_type() helper function

Some drivers require knowledge of what connection handle is assigned
to what connection link type (ACL or SCO/eSCO). Instead of having each
driver implement connection tracking, provide a simple helper function
for lookup of the link type.
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>

include/net/bluetooth/hci.h

@@ -274,6 +274,7 @@ enum {
 /* Low Energy links do not have defined link type. Use invented one */
 #define LE_LINK		0x80
 #define AMP_LINK	0x81
+#define INVALID_LINK	0xff
 
 /* LMP features */
 #define LMP_3SLOT	0x01

include/net/bluetooth/hci_core.h

@@ -646,6 +646,26 @@ static inline unsigned int hci_conn_count(struct hci_dev *hdev)
 	return c->acl_num + c->amp_num + c->sco_num + c->le_num;
 }
 
+static inline __u8 hci_conn_lookup_type(struct hci_dev *hdev, __u16 handle)
+{
+	struct hci_conn_hash *h = &hdev->conn_hash;
+	struct hci_conn *c;
+	__u8 type = INVALID_LINK;
+
+	rcu_read_lock();
+
+	list_for_each_entry_rcu(c, &h->list, list) {
+		if (c->handle == handle) {
+			type = c->type;
+			break;
+		}
+	}
+
+	rcu_read_unlock();
+
+	return type;
+}
+
 static inline struct hci_conn *hci_conn_hash_lookup_handle(struct hci_dev *hdev,
 								__u16 handle)
 {