Add function documentation.

public/tee_client_api_extensions.h

@@ -35,6 +35,41 @@
 extern "C" {
 #endif
 
+/**
+ * TEEC_OpenSessionEx() - Opens a new session with the specified trusted
+ *                        application with generic RPC handling support.
+ *
+ * @param context            The initialized TEE context structure in which
+ *                           scope to open the session.
+ * @param session            The session to initialize.
+ * @param destination        A structure identifying the trusted application
+ *                           with which to open a session.
+ *
+ * @param connectionMethod   The connection method to use.
+ * @param connectionData     Any data necessary to connect with the chosen
+ *                           connection method. Not supported, should be set to
+ *                           NULL.
+ * @param operation          An operation structure to use in the session. May
+ *                           be set to NULL to signify no operation structure
+ *                           needed.
+ *
+ * @param returnOrigin       A parameter which will hold the error origin if
+ *                           this function returns any value other than
+ *                           TEEC_SUCCESS.
+ *
+ * @param rpcCallback        A function to invoke when a generic RPC request
+ *                           arrives from the TA. This function retuns a value
+ *                           that indicates if the request was processed
+ *                           successfully (e.g. the function ID was valid), not
+ *                           the return value of the underlying function
+ * 
+ * @param rpc_context        An arbitrary pointer to pass to the function
+ *                           referenced by rpc_callback.
+ *                           
+ * @return TEEC_SUCCESS      OpenSession successfully opened a new session.
+ * @return TEEC_Result       Something failed.
+ *
+ */
 TEEC_Result TEEC_OpenSessionEx(TEEC_Context *ctx,
 			       TEEC_Session *session,
 			       const TEEC_UUID *destination,