+/**
+ * Defines the function signature requide for JTAG event callback
+ * functions, which are added with jtag_register_event_callback()
+ * and removed jtag_unregister_event_callback().
+ * @param event The event to handle.
+ * @param prive A pointer to data that was passed to
+ * jtag_register_event_callback().
+ * @returns Must return ERROR_OK on success, or an error code on failure.
+ *
+ * @todo Change to return void or define a use for its return code.
+ */
+typedef int (*jtag_event_handler_t)(enum jtag_event event, void* priv);
+
+extern int jtag_register_event_callback(jtag_event_handler_t f, void *x);
+extern int jtag_unregister_event_callback(jtag_event_handler_t f, void *x);
+
+extern int jtag_call_event_callbacks(enum jtag_event event);
+
+
+/// @returns The current JTAG speed setting.
+int jtag_get_speed(void);
+/**
+ * Given a @a speed setting, use the interface @c speed_div callback to
+ * adjust the setting.
+ * @param speed The speed setting to convert back to readable KHz.
+ * @returns ERROR_OK if the interface has not been initialized or on success;
+ * otherwise, the error code produced by the @c speed_div callback.
+ */
+int jtag_get_speed_readable(int *speed);
+/**
+ * Set the JTAG speed. This routine will call the underlying
+ * interface @c speed callback, if the interface has been initialized.
+ * @param speed The new speed setting.
+ * @returns ERROR_OK during configuration or on success, or an error
+ * code returned from the interface @c speed callback.
+ */
+int jtag_set_speed(int speed);