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/*
* U-boot - x86 Startup Code
*
* (C) Copyright 2008-2011
* Graeme Russ, <graeme.russ@gmail.com>
*
* (C) Copyright 2002
* Daniel Engström, Omicron Ceti AB, <daniel@omicron.se>
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <config.h>
#include <version.h>
#include <asm/global_data.h>
#include <asm/processor.h>
#include <asm/processor-flags.h>
#include <generated/generic-asm-offsets.h>
.section .text
.code32
.globl _start
.type _start, @function
.globl _x86boot_start
_x86boot_start:
/*
* This is the fail safe 32-bit bootstrap entry point. The
* following code is not executed from a cold-reset (actually, a
* lot of it is, but from real-mode after cold reset. It is
* repeated here to put the board into a state as close to cold
* reset as necessary)
*/
cli
cld
/* Turn off cache (this might require a 486-class CPU) */
movl %cr0, %eax
orl $(X86_CR0_NW | X86_CR0_CD), %eax
movl %eax, %cr0
wbinvd
/* Tell 32-bit code it is being entered from an in-RAM copy */
movw $GD_FLG_WARM_BOOT, %bx
jmp 1f
_start:
/*
* This is the 32-bit cold-reset entry point. Initialize %bx to 0
* in case we're preceeded by some sort of boot stub.
*/
movw $GD_FLG_COLD_BOOT, %bx
1:
/* Load the segement registes to match the gdt loaded in start16.S */
movl $(X86_GDT_ENTRY_32BIT_DS * X86_GDT_ENTRY_SIZE), %eax
movw %ax, %fs
movw %ax, %ds
movw %ax, %gs
movw %ax, %es
movw %ax, %ss
/* Clear the interrupt vectors */
lidt blank_idt_ptr
/* Early platform init (setup gpio, etc ) */
jmp early_board_init
.globl early_board_init_ret
early_board_init_ret:
/* Initialise Cache-As-RAM */
jmp car_init
.globl car_init_ret
car_init_ret:
/*
* We now have CONFIG_SYS_CAR_SIZE bytes of Cache-As-RAM (or SRAM,
* or fully initialised SDRAM - we really don't care which)
* starting at CONFIG_SYS_CAR_ADDR to be used as a temporary stack
*/
/* Stack grows down from top of CAR */
movl $(CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE), %esp
/* Reserve space on stack for global data */
subl $GENERATED_GBL_DATA_SIZE, %esp
/* Align global data to 16-byte boundary */
andl $0xfffffff0, %esp
/* Zero the global data since it won't happen later */
xorl %eax, %eax
movl $GENERATED_GBL_DATA_SIZE, %ecx
movl %esp, %edi
rep stosb
/* Setup first parameter to setup_gdt */
movl %esp, %eax
/* Reserve space for global descriptor table */
subl $X86_GDT_SIZE, %esp
/* Align temporary global descriptor table to 16-byte boundary */
andl $0xfffffff0, %esp
/* Set second parameter to setup_gdt */
movl %esp, %edx
/* Setup global descriptor table so gd->xyz works */
call setup_gdt
/* Set parameter to board_init_f() to boot flags */
xorl %eax, %eax
movw %bx, %ax
/* Enter, U-boot! */
call board_init_f
/* indicate (lack of) progress */
movw $0x85, %ax
jmp die
.globl board_init_f_r_trampoline
.type board_init_f_r_trampoline, @function
board_init_f_r_trampoline:
/*
* SDRAM has been initialised, U-Boot code has been copied into
* RAM, BSS has been cleared and relocation adjustments have been
* made. It is now time to jump into the in-RAM copy of U-Boot
*
* %eax = Address of top of new stack
*/
/* Stack grows down from top of SDRAM */
movl %eax, %esp
/* Reserve space on stack for global data */
subl $GENERATED_GBL_DATA_SIZE, %esp
/* Align global data to 16-byte boundary */
andl $0xfffffff0, %esp
/* Setup first parameter to memcpy (and setup_gdt) */
movl %esp, %eax
/* Setup second parameter to memcpy */
fs movl 0, %edx
/* Set third parameter to memcpy */
movl $GENERATED_GBL_DATA_SIZE, %ecx
/* Copy global data from CAR to SDRAM stack */
call memcpy
/* Reserve space for global descriptor table */
subl $X86_GDT_SIZE, %esp
/* Align global descriptor table to 16-byte boundary */
andl $0xfffffff0, %esp
/* Set second parameter to setup_gdt */
movl %esp, %edx
/* Setup global descriptor table so gd->xyz works */
call setup_gdt
/* Re-enter U-Boot by calling board_init_f_r */
call board_init_f_r
die:
hlt
jmp die
hlt
blank_idt_ptr:
.word 0 /* limit */
.long 0 /* base */
.p2align 2 /* force 4-byte alignment */
multiboot_header:
/* magic */
.long 0x1BADB002
/* flags */
.long (1 << 16)
/* checksum */
.long -0x1BADB002 - (1 << 16)
/* header addr */
.long multiboot_header - _x86boot_start + CONFIG_SYS_TEXT_BASE
/* load addr */
.long CONFIG_SYS_TEXT_BASE
/* load end addr */
.long 0
/* bss end addr */
.long 0
/* entry addr */
.long CONFIG_SYS_TEXT_BASE
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