Subversion Repositories openrisc_2011-10-31

/*  bspclean.c

 *

 *  These routines return control to 167Bug after a normal exit from the

 *  application.

 *

 *  COPYRIGHT (c) 1989-1999.

 *  On-Line Applications Research Corporation (OAR).

 *

 *  The license and distribution terms for this file may be

 *  found in the file LICENSE in this distribution or at

 *  http://www.OARcorp.com/rtems/license.html.

 *

 *  Modifications of respective RTEMS files:

 *  Copyright (c) 1998, National Research Council of Canada

 *

 *  $Id: bspclean.c,v 1.2 2001-09-27 12:00:20 chris Exp $

 */

#include <rtems.h>

#include <bsp.h>

#include <page_table.h>

/*

 *  bsp_return_to_monitor_trap

 *

 *  Switch the VBR back to ROM and make a .RETURN syscall to return control to

 *  167 Bug. If 167Bug ever returns, restart the application.

 *

 *  Input parameters: NONE

 *

 *  Output parameters: NONE

 *

 *  Return values: NONE

 */

static void bsp_return_to_monitor_trap( void )

{

  extern void start( void );

  register volatile void *start_addr;

  page_table_teardown();

  lcsr->intr_ena = 0;               /* disable interrupts */

  m68k_set_vbr(0xFFE00000);         /* restore 167Bug vectors */

  asm volatile( "trap   #15         /* trap to 167Bug */

                 .short 0x63" );    /* return to 167Bug (.RETURN) */

  /* restart program */

  start_addr = start;

  asm volatile( "jmp %0@" : "=a" (start_addr) : "0" (start_addr) );

}

/*

 *  bsp_cleanup

 *

 *  This code was copied from other MC680x0 MVME BSPs.

 *  Our guess is that someone was concerned about the CPU no longer being in

 *  supervisor mode when they got here. This function forces the CPU back to

 *  supervisor mode so the VBR may be changed. It places the address of the

 *  function that makes a 167Bug .RETURN syscall in the trap 13 entry in the

 *  exception vector, and then issues a trap 13 call. It is also possible that

 *  the code was copied from some other OS that does run tasks in user mode.

 *  In any case, it appears to be a bit of paranoia, and could lead to

 *  problems if 167Bug is invoked before we get to switch the VBR back to

 *  167Bug because trap 13 is documented as being reserved for the internal

 *  use of the debugger.

 *

 *  Prototyped in rtems/c/src/lib/libbsp/m68k/mvme167/include/bsp.h

 *

 *  Input parameters: NONE

 *

 *  Output parameters: NONE

 *

 *  Return values: DOES NOT RETURN

 */

void bsp_cleanup( void )

{

   M68Kvec[ 45 ] = bsp_return_to_monitor_trap;

   asm volatile( "trap #13" );

}