Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

/*

 * Copyright (C) Paul Mackerras 1997.

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version

 * 2 of the License, or (at your option) any later version.

 *

 * NOTE: this code runs in 32 bit mode and is packaged as ELF32.

 */

#include "ppc_asm.h"

        .text

        /* a procedure descriptor used when booting this as a COFF file */

        .globl  _zimage_start_opd

_zimage_start_opd:

        .long   _zimage_start, 0, 0, 0

        .weak   _zimage_start

        .globl  _zimage_start

_zimage_start:

        .globl  _zimage_start_lib

_zimage_start_lib:

        /* Work out the offset between the address we were linked at

           and the address where we're running. */

        bl      1f

1:      mflr    r0

        lis     r9,1b@ha

        addi    r9,r9,1b@l

        subf.   r0,r9,r0

        beq     3f              /* if running at same address as linked */

        /* The .got2 section contains a list of addresses, so add

           the address offset onto each entry. */

        lis     r9,__got2_start@ha

        addi    r9,r9,__got2_start@l

        lis     r8,__got2_end@ha

        addi    r8,r8,__got2_end@l

        subf.   r8,r9,r8

        beq     3f

        srwi.   r8,r8,2

        mtctr   r8

        add     r9,r0,r9

2:      lwz     r8,0(r9)

        add     r8,r8,r0

        stw     r8,0(r9)

        addi    r9,r9,4

        bdnz    2b

        /* Do a cache flush for our text, in case the loader didn't */

3:      lis     r9,_start@ha

        addi    r9,r9,_start@l

        add     r9,r0,r9

        lis     r8,_etext@ha

        addi    r8,r8,_etext@l

        add     r8,r0,r8

4:      dcbf    r0,r9

        icbi    r0,r9

        addi    r9,r9,0x20

        cmplw   cr0,r9,r8

        blt     4b

        sync

        isync

        /* Clear the BSS */

        lis     r9,__bss_start@ha

        addi    r9,r9,__bss_start@l

        add     r9,r0,r9

        lis     r8,_end@ha

        addi    r8,r8,_end@l

        add     r8,r0,r8

        li      r10,0

5:      stw     r10,0(r9)

        addi    r9,r9,4

        cmplw   cr0,r9,r8

        blt     5b

        /* Possibly set up a custom stack */

.weak   _platform_stack_top

        lis     r8,_platform_stack_top@ha

        addi    r8,r8,_platform_stack_top@l

        cmpwi   r8,0

        beq     6f

        add     r8,r0,r8

        lwz     r1,0(r8)

        add     r1,r0,r1

        li      r0,0

        stwu    r0,-16(r1)      /* establish a stack frame */

6:

        /* Call platform_init() */

        bl      platform_init

        /* Call start */

        b       start