1/* 2 * U-boot - x86 Startup Code 3 * 4 * (C) Copyright 2008-2011 5 * Graeme Russ, <graeme.russ@gmail.com> 6 * 7 * (C) Copyright 2002 8 * Daniel Engström, Omicron Ceti AB, <daniel@omicron.se> 9 * 10 * See file CREDITS for list of people who contributed to this 11 * project. 12 * 13 * This program is free software; you can redistribute it and/or 14 * modify it under the terms of the GNU General Public License as 15 * published by the Free Software Foundation; either version 2 of 16 * the License, or (at your option) any later version. 17 * 18 * This program is distributed in the hope that it will be useful, 19 * but WITHOUT ANY WARRANTY; without even the implied warranty of 20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 21 * GNU General Public License for more details. 22 * 23 * You should have received a copy of the GNU General Public License 24 * along with this program; if not, write to the Free Software 25 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, 26 * MA 02111-1307 USA 27 */ 28 29#include <config.h> 30#include <version.h> 31#include <asm/global_data.h> 32#include <asm/processor.h> 33#include <asm/processor-flags.h> 34#include <generated/generic-asm-offsets.h> 35 36.section .text 37.code32 38.globl _start 39.type _start, @function 40.globl _x86boot_start 41_x86boot_start: 42 /* 43 * This is the fail safe 32-bit bootstrap entry point. The 44 * following code is not executed from a cold-reset (actually, a 45 * lot of it is, but from real-mode after cold reset. It is 46 * repeated here to put the board into a state as close to cold 47 * reset as necessary) 48 */ 49 cli 50 cld 51 52 /* Turn off cache (this might require a 486-class CPU) */ 53 movl %cr0, %eax 54 orl $(X86_CR0_NW | X86_CR0_CD), %eax 55 movl %eax, %cr0 56 wbinvd 57 58_start: 59 /* This is the 32-bit cold-reset entry point */ 60 61 /* Load the segement registes to match the gdt loaded in start16.S */ 62 movl $(X86_GDT_ENTRY_32BIT_DS * X86_GDT_ENTRY_SIZE), %eax 63 movw %ax, %fs 64 movw %ax, %ds 65 movw %ax, %gs 66 movw %ax, %es 67 movw %ax, %ss 68 69 /* Clear the interrupt vectors */ 70 lidt blank_idt_ptr 71 72 /* Early platform init (setup gpio, etc ) */ 73 jmp early_board_init 74.globl early_board_init_ret 75early_board_init_ret: 76 77 /* Initialise Cache-As-RAM */ 78 jmp car_init 79.globl car_init_ret 80car_init_ret: 81 /* 82 * We now have CONFIG_SYS_CAR_SIZE bytes of Cache-As-RAM (or SRAM, 83 * or fully initialised SDRAM - we really don't care which) 84 * starting at CONFIG_SYS_CAR_ADDR to be used as a temporary stack 85 */ 86 87 /* Stack grows down from top of CAR */ 88 movl $(CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE), %esp 89 90 /* Reserve space on stack for global data */ 91 subl $GENERATED_GBL_DATA_SIZE, %esp 92 93 /* Align global data to 16-byte boundary */ 94 andl $0xfffffff0, %esp 95 96 /* Setup first parameter to setup_gdt */ 97 movl %esp, %eax 98 99 /* Reserve space for global descriptor table */ 100 subl $X86_GDT_SIZE, %esp 101 102 /* Align temporary global descriptor table to 16-byte boundary */ 103 andl $0xfffffff0, %esp 104 105 /* Set second parameter to setup_gdt */ 106 movl %esp, %edx 107 108 /* gd->gd_addr = gd (Required to allow gd->xyz to work) */ 109 movl %eax, (%eax) 110 111 /* Setup global descriptor table so gd->xyz works */ 112 call setup_gdt 113 114 /* Set parameter to board_init_f() to boot flags */ 115 xorl %eax, %eax 116 movw %bx, %ax 117 118 /* Enter, U-boot! */ 119 call board_init_f 120 121 /* indicate (lack of) progress */ 122 movw $0x85, %ax 123 jmp die 124 125.globl board_init_f_r_trampoline 126.type board_init_f_r_trampoline, @function 127board_init_f_r_trampoline: 128 /* 129 * SDRAM has been initialised, U-Boot code has been copied into 130 * RAM, BSS has been cleared and relocation adjustments have been 131 * made. It is now time to jump into the in-RAM copy of U-Boot 132 * 133 * %eax = Address of top of new stack 134 */ 135 136 /* Stack grows down from top of SDRAM */ 137 movl %eax, %esp 138 139 /* Reserve space on stack for global data */ 140 subl $GENERATED_GBL_DATA_SIZE, %esp 141 142 /* Align global data to 16-byte boundary */ 143 andl $0xfffffff0, %esp 144 145 /* Setup first parameter to memcpy (and setup_gdt) */ 146 movl %esp, %eax 147 148 /* Setup second parameter to memcpy */ 149 fs movl 0, %edx 150 151 /* Set third parameter to memcpy */ 152 movl $GENERATED_GBL_DATA_SIZE, %ecx 153 154 /* Copy global data from CAR to SDRAM stack */ 155 call memcpy 156 157 /* Reserve space for global descriptor table */ 158 subl $X86_GDT_SIZE, %esp 159 160 /* Align global descriptor table to 16-byte boundary */ 161 andl $0xfffffff0, %esp 162 163 /* Set second parameter to setup_gdt */ 164 movl %esp, %edx 165 166 /* gd->gd_addr = gd (Required to allow gd->xyz to work) */ 167 movl %eax, (%eax) 168 169 /* Setup global descriptor table so gd->xyz works */ 170 call setup_gdt 171 172 /* Re-enter U-Boot by calling board_init_f_r */ 173 call board_init_f_r 174 175die: 176 hlt 177 jmp die 178 hlt 179 180blank_idt_ptr: 181 .word 0 /* limit */ 182 .long 0 /* base */ 183 184 .p2align 2 /* force 4-byte alignment */ 185 186multiboot_header: 187 /* magic */ 188 .long 0x1BADB002 189 /* flags */ 190 .long (1 << 16) 191 /* checksum */ 192 .long -0x1BADB002 - (1 << 16) 193 /* header addr */ 194 .long multiboot_header - _x86boot_start + CONFIG_SYS_TEXT_BASE 195 /* load addr */ 196 .long CONFIG_SYS_TEXT_BASE 197 /* load end addr */ 198 .long 0 199 /* bss end addr */ 200 .long 0 201 /* entry addr */ 202 .long CONFIG_SYS_TEXT_BASE 203