Add the beginning of a GDB based Debug Agent. IA-32 and X64 don't have low level interrupt code yet. I've been testing on ARM.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@10334 6f19259b-4bc3-4df7-8a09-765794883524

EmbeddedPkg/Include/Library/DebugAgentTimerLib.h

@@ -0,0 +1,62 @@
+/** @file
+  Platform specific Debug Agent abstraction for timer used by the agent. 
+
+  The timer is used by the debugger to break into a running program.
+
+  Copyright (c) 2008-2010, Apple Inc. All rights reserved.
+  
+  All rights reserved. This program and the accompanying materials
+  are licensed and made available under the terms and conditions of the BSD License
+  which accompanies this distribution.  The full text of the license may be found at
+  http://opensource.org/licenses/bsd-license.php
+
+  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+
+**/
+
+#ifndef __GDB_TIMER_LIB__
+#define __GDB_TIMER_LIB__
+
+
+
+/**
+  Setup all the hardware needed for the debug agents timer.
+
+  This function is used to set up debug enviroment. It may enable interrupts.
+
+**/
+VOID
+EFIAPI
+DebugAgentTimerIntialize (
+  VOID
+  );
+  
+
+/**
+  Set the period for the debug agent timer. Zero means disable the timer.
+
+  @param[in] TimerPeriodMilliseconds    Frequency of the debug agent timer.
+
+**/  
+VOID
+EFIAPI
+DebugAgentTimerSetPeriod (
+  IN  UINT32  TimerPeriodMilliseconds
+  );
+  
+
+/**
+  Perform End Of Interrupt for the debug agent timer. This is called in the 
+  interrupt handler after the interrupt has been processed. 
+
+**/  
+VOID
+EFIAPI
+DebugAgentTimerEndOfInterrupt (
+  VOID
+  );
+  
+#endif
+  
+