| /* Copyright (c) 1997 Paul Mackerras <paulus@cs.anu.edu.au> |
| * Initial Power Macintosh COFF version. |
| * Copyright (c) 1999 Grant Erickson <grant@lcse.umn.edu> |
| * Modifications for IBM PowerPC 400-class processor evaluation |
| * boards. |
| * |
| * Module name: crt0.S |
| * |
| * Description: |
| * Boot loader execution entry point. Clears out .bss section as per |
| * ANSI C requirements. Invalidates and flushes the caches over the |
| * range covered by the boot loader's .text section. Sets up a stack |
| * below the .text section entry point. |
| * |
| * 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. |
| */ |
| |
| #include <asm/ppc_asm.h> |
| |
| .text |
| |
| .globl _start |
| _start: |
| #ifdef XCOFF |
| .long __start,0,0 |
| |
| .globl __start |
| __start: |
| #endif |
| |
| ## Flush and invalidate the caches for the range in memory covering |
| ## the .text section of the boot loader |
| |
| lis r9,_start@h # r9 = &_start |
| lis r8,_etext@ha # |
| addi r8,r8,_etext@l # r8 = &_etext |
| 3: dcbf r0,r9 # Flush the data cache |
| icbi r0,r9 # Invalidate the instruction cache |
| addi r9,r9,0x10 # Increment by one cache line |
| cmplw cr0,r9,r8 # Are we at the end yet? |
| blt 3b # No, keep flushing and invalidating |
| sync # sync ; isync after flushing the icache |
| isync |
| |
| ## Clear out the BSS as per ANSI C requirements |
| |
| lis r7,_end@ha |
| addi r7,r7,_end@l # r7 = &_end |
| lis r8,__bss_start@ha # |
| addi r8,r8,__bss_start@l # r8 = &_bss_start |
| |
| ## Determine how large an area, in number of words, to clear |
| |
| subf r7,r8,r7 # r7 = &_end - &_bss_start + 1 |
| addi r7,r7,3 # r7 += 3 |
| srwi. r7,r7,2 # r7 = size in words. |
| beq 2f # If the size is zero, do not bother |
| addi r8,r8,-4 # r8 -= 4 |
| mtctr r7 # SPRN_CTR = number of words to clear |
| li r0,0 # r0 = 0 |
| 1: stwu r0,4(r8) # Clear out a word |
| bdnz 1b # If we are not done yet, keep clearing |
| 2: |
| |
| #ifdef CONFIG_40x |
| ## Set up the stack |
| |
| lis r9,_start@h # r9 = &_start (text section entry) |
| ori r9,r9,_start@l |
| subi r1,r9,64 # Start the stack 64 bytes below _start |
| clrrwi r1,r1,4 # Make sure it is aligned on 16 bytes. |
| li r0,0 |
| stwu r0,-16(r1) |
| mtlr r9 |
| #endif |
| |
| b start # All done, start the real work. |