board/sc520_cdp/sc520_cdp_asm16.S

   1 /*
   2  * (C) Copyright 2002
   3  * Daniel Engström, Omicron Ceti AB <daniel@omicron.se>.
   4  *
   5  * See file CREDITS for list of people who contributed to this
   6  * project.
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License as
  10  * published by the Free Software Foundation; either version 2 of
  11  * the License, or (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  21  * MA 02111-1307 USA
  22  */
  23
  24 /*
  25  * 16bit initialization code.
  26  * This code have to map the area of the boot flash
  27  * that is used by U-boot to its final destination.
  28  */
  29
  30 .text
  31 .section .start16, "ax"
  32 .code16
  33 .globl board_init16
  34 board_init16:
  35         /* Alias MMCR to 0xdf000 */
  36         movw    $0xfffc, %dx
  37         movl    $0x800df0cb, %eax
  38         outl    %eax, %dx
  39
  40         /* Set ds to point to MMCR alias */
  41         movw    $0xdf00, %ax
  42         movw    %ax, %ds
  43
  44         /* Map the entire flash at 0x38000000
  45          * (with BOOTCS and PAR14, use 0xabfff800 for ROMCS1) */
  46         movl    $0xc0, %edi
  47         movl    $0x8bfff800, %eax
  48         movl    %eax, (%di)
  49
  50         /* Disable SDRAM write buffer */
  51         movw    $0x40,%di
  52         xorw    %ax,%ax
  53         movb    %al, (%di)
  54
  55         /* Disabe MMCR alias */
  56         movw    $0xfffc, %dx
  57         movl    $0x000000cb, %eax
  58         outl    %eax, %dx
  59
  60         /* the return address is tored in bp */
  61         jmp     *%bp
  62
  63
  64 .section .bios, "ax"
  65 .code16
  66 .globl realmode_reset
  67 realmode_reset:
  68         /* Alias MMCR to 0xdf000 */
  69         movw    $0xfffc, %dx
  70         movl    $0x800df0cb, %eax
  71         outl    %eax, %dx
  72
  73         /* Set ds to point to MMCR alias */
  74         movw    $0xdf00, %ax
  75         movw    %ax, %ds
  76
  77         /* issue software reset thorugh MMCR */
  78         movl    $0xd72, %edi
  79         movb    $0x01, %al
  80         movb    %al, (%di)
  81
  82 1:      hlt
  83         jmp     1