mcf5213_lo.s

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/*
 * File:    mcf5213.s
 * Purpose: Low-level routines for the MCF5213/12/11.
 *
 * Notes:   
 */

#ifdef _UNDERSCORE_
#define board_sysinit   _board_sysinit
#define common_startup  _common_startup
#define cpu_startup     _cpu_startup
#define main            _main
#define __IPSBAR        ___IPSBAR   
#define __SRAM          ___SRAM     
#define __FLASH         ___FLASH    
#define __SP_INIT       ___SP_INIT  
#endif
 
    .extern __IPSBAR
    .extern __SRAM
    .extern __FLASH
    .extern __SP_INIT
    .extern board_sysinit
    .extern common_startup
    .extern cpu_startup
    .extern main

    .global asm_startmeup
    .global _asm_startmeup
    .global d0_reset
    .global _d0_reset
    .global d1_reset
    .global _d1_reset

    .data
    
d0_reset:
_d0_reset:  .long   0
d1_reset:
_d1_reset:  .long   0

    .text

/********************************************************************
 * 
 * This is the main entry point upon hard reset.  The memory map is
 * setup based on linker file definitions, then the higher level
 * system initialization routine is called.  Finally, we jump to the
 * "main" process. 
 */
asm_startmeup:
_asm_startmeup:

    /* Save off reset values of D0 and D1 */
    move.l  d0,d6
    move.l  d1,d7
    
    /* Initialize RAMBAR1: locate SRAM and validate it */
    move.l  #__SRAM,d0
    add.l   #0x21,d0
    movec   d0,RAMBAR1

    /* Locate Stack Pointer */ 
    move.l  #__SP_INIT,sp

    /* Initialize IPSBAR */
    move.l  #__IPSBAR,d0
    add.l   #0x1,d0
    move.l  d0,0x40000000
    
    /* Initialize FLASHBAR */
    move.l  #__FLASH,d0
    cmp.l   #0x00000000,d0
    bne     change_flashbar
    add.l   #0x21,d0
    movec   d0,RAMBAR0

_continue_startup:

    /* Locate Stack Pointer */ 
    move.l  #__SP_INIT,sp

    /* Initialize the system */
    jsr     board_sysinit

    /* Common startup code */
    jsr     common_startup

    /* Save off intial D0 and D1 to RAM */
    move.l  d6,d0_reset
    move.l  d7,d1_reset
    
    /* CPU specific startup code */
    jsr     cpu_startup

    /* Jump to the main process */
    jsr     main
    
    bra     .
    nop
    nop
    halt

change_flashbar:
    /* 
     * The following sequence is used to set FLASHBAR. Since we may 
     * be executing from Flash, we must put the routine into SRAM for
     * execution and then jump back to Flash using the new address.
     *
     * The following instructions are coded into the SRAM:
     *
     * move.l   #(__FLASH + 0x21),d0
     * movec    d0, RAMBAR0
     * jmp      _continue_startup
     *
     * An arbitrary SRAM address is chosen until the real address
     * can be loaded.
     *
     * This routine is not necessary if the default Flash address
     * (0x00000000) is used.
     *
     * If running in SRAM, change_flashbar should not be executed 
     */

    move.l  #__SRAM,a0

    /* Code "move.l #(__FLASH + 0x21),d0" into SRAM */
    move.w  #0x203C,d0
    move.w  d0,(a0)+
    move.l  #__FLASH,d0
    add.l   #0x21,d0
    move.l  d0,(a0)+
    
    /* Code "movec d0,FLASHBAR" into SRAM */
    move.l  #0x4e7b0C04,d0
    move.l  d0,(a0)+
        
    /* Code "jmp _continue_startup" into SRAM */
    move.w  #0x4EF9,d0
    move.w  d0,(a0)+
    move.l  #_continue_startup,d0
    move.l  d0,(a0)+

    /* Jump to code segment in internal SRAM */
    jmp     __SRAM

/********************************************************************/

    .end