dev: Refactor terminal<->UART interface to make it more generic

The terminal currently assumes that the transport to the guest always
inherits from the Uart class. This assumption breaks when
implementing, for example, a VirtIO consoles. This patch removes this
assumption by adding pointer to the from the terminal to the uart and
replacing it with a more general callback interface. The Uart, or any
other class using the terminal, class implements an instance of the
callbacks class and registers it with the terminal.

1 files changed, 15 insertions, 2 deletions

diff --git a/src/dev/terminal.hh b/src/dev/terminal.hh
index e2322d7c2..f7a860ac5 100644
--- a/src/dev/terminal.hh
+++ b/src/dev/terminal.hh
@@ -38,6 +38,7 @@
 
 #include <iostream>
 
+#include "base/callback.hh"
 #include "base/circlebuf.hh"
 #include "base/pollevent.hh"
 #include "base/socket.hh"
@@ -46,12 +47,24 @@
 #include "sim/sim_object.hh"
 
 class TerminalListener;
-class Uart;
 
 class Terminal : public SimObject
 {
   public:
-    Uart *uart;
+    /**
+     * Register a data available callback into the transport layer.
+     *
+     * The terminal needs to call the underlying transport layer to
+     * inform it of available data. The transport layer uses this
+     * method to register a callback that informs it of pending data.
+     *
+     * @param c Callback instance from transport layer.
+     */
+    void regDataAvailCallback(Callback *c);
+
+  protected:
+    /** Currently registered transport layer callbacks */
+    Callback *termDataAvail;
 
   protected:
     class ListenEvent : public PollEvent