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/* bspclean.c
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*
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* These routines return control to 167Bug after a normal exit from the
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* application.
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*
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* COPYRIGHT (c) 1989-1999.
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* On-Line Applications Research Corporation (OAR).
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*
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* The license and distribution terms for this file may be
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* found in the file LICENSE in this distribution or at
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* http://www.OARcorp.com/rtems/license.html.
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*
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* Modifications of respective RTEMS files:
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* Copyright (c) 1998, National Research Council of Canada
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*
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* $Id: bspclean.c,v 1.2 2001-09-27 12:00:20 chris Exp $
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*/
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#include <rtems.h>
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#include <bsp.h>
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#include <page_table.h>
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/*
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* bsp_return_to_monitor_trap
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*
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* Switch the VBR back to ROM and make a .RETURN syscall to return control to
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* 167 Bug. If 167Bug ever returns, restart the application.
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*
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* Input parameters: NONE
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*
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* Output parameters: NONE
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*
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* Return values: NONE
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*/
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static void bsp_return_to_monitor_trap( void )
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{
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extern void start( void );
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register volatile void *start_addr;
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page_table_teardown();
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lcsr->intr_ena = 0; /* disable interrupts */
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m68k_set_vbr(0xFFE00000); /* restore 167Bug vectors */
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asm volatile( "trap #15 /* trap to 167Bug */
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.short 0x63" ); /* return to 167Bug (.RETURN) */
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/* restart program */
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start_addr = start;
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asm volatile( "jmp %0@" : "=a" (start_addr) : "0" (start_addr) );
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}
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/*
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* bsp_cleanup
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*
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* This code was copied from other MC680x0 MVME BSPs.
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* Our guess is that someone was concerned about the CPU no longer being in
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* supervisor mode when they got here. This function forces the CPU back to
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* supervisor mode so the VBR may be changed. It places the address of the
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* function that makes a 167Bug .RETURN syscall in the trap 13 entry in the
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* exception vector, and then issues a trap 13 call. It is also possible that
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* the code was copied from some other OS that does run tasks in user mode.
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* In any case, it appears to be a bit of paranoia, and could lead to
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* problems if 167Bug is invoked before we get to switch the VBR back to
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* 167Bug because trap 13 is documented as being reserved for the internal
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* use of the debugger.
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*
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* Prototyped in rtems/c/src/lib/libbsp/m68k/mvme167/include/bsp.h
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*
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* Input parameters: NONE
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*
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* Output parameters: NONE
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*
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* Return values: DOES NOT RETURN
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*/
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void bsp_cleanup( void )
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{
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M68Kvec[ 45 ] = bsp_return_to_monitor_trap;
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asm volatile( "trap #13" );
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}
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