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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 <asm/global_data.h>
#include <asm/post.h>
#include <asm/processor.h>
#include <asm/processor-flags.h>
#include <generated/generic-asm-offsets.h>
#include <generated/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.
*
* This code is used when booting from another boot loader like
* coreboot or EFI. So we repeat some of the same init found in
* start16.
*/
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 */
movl $GD_FLG_WARM_BOOT, %ebx
/*
* Zero the BIST (Built-In Self Test) value since we don't have it.
* It must be 0 or the previous loader would have reported an error.
*/
movl $0, %ebp
jmp 1f
/* Add a way for tools to discover the _start entry point */
.align 4
.long 0x12345678
_start:
/*
* This is the 32-bit cold-reset entry point, coming from start16.
* Set %ebx to GD_FLG_COLD_BOOT to indicate this.
*/
movl $GD_FLG_COLD_BOOT, %ebx
/* Save BIST */
movl %eax, %ebp
1:
/* Save table pointer */
movl %ecx, %esi
/* Load the segement registers 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
/*
* Critical early platform init - generally not used, we prefer init
* to happen later when we have a console, in case something goes
* wrong.
*/
jmp early_board_init
.globl early_board_init_ret
early_board_init_ret:
post_code(POST_START)
/* Initialise Cache-As-RAM */
jmp car_init
.globl car_init_ret
car_init_ret:
#ifndef CONFIG_HAVE_FSP
/*
* 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
* and early malloc() area. The MRC requires some space at the top.
*
* Stack grows down from top of CAR. We have:
*
* top-> CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE
* MRC area
* global_data with x86 global descriptor table
* early malloc area
* stack
* bottom-> CONFIG_SYS_CAR_ADDR
*/
movl $(CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE - 4), %esp
#ifdef CONFIG_DCACHE_RAM_MRC_VAR_SIZE
subl $CONFIG_DCACHE_RAM_MRC_VAR_SIZE, %esp
#endif
#else
/*
* When we get here after car_init(), esp points to a temporary stack
* and esi holds the HOB list address returned by the FSP.
*/
#endif
/* Set up global data */
mov %esp, %eax
call board_init_f_mem
mov %eax, %esp
/*
* Debug UART is available here although it may not be plumbed out
* to pins depending on the board. To use it:
*
* call debug_uart_init
* mov $'a', %eax
* call printch
*/
/* Get address of global_data */
mov %fs:0, %edx
#ifdef CONFIG_HAVE_FSP
/* Store the HOB list if we have one */
test %esi, %esi
jz skip_hob
movl %esi, GD_HOB_LIST(%edx)
skip_hob:
#else
/* Store table pointer */
movl %esi, GD_TABLE(%edx)
#endif
/* Store BIST */
movl %ebp, GD_BIST(%edx)
/* Set parameter to board_init_f() to boot flags */
post_code(POST_START_DONE)
xorl %eax, %eax
/* 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
/* See if we need to disable CAR */
.weak car_uninit
movl $car_uninit, %eax
cmpl $0, %eax
jz 1f
call car_uninit
1:
/* 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 */
/* Add a multiboot header so U-Boot can be loaded by GRUB2 */
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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