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 /* Tell 32-bit code it is being entered from an in-RAM copy */ 59 movw $GD_FLG_WARM_BOOT, %bx 60 jmp 1f 61_start: 62 /* 63 * This is the 32-bit cold-reset entry point. Initialize %bx to 0 64 * in case we're preceeded by some sort of boot stub. 65 */ 66 movw $GD_FLG_COLD_BOOT, %bx 671: 68 69 /* Load the segement registes to match the gdt loaded in start16.S */ 70 movl $(X86_GDT_ENTRY_32BIT_DS * X86_GDT_ENTRY_SIZE), %eax 71 movw %ax, %fs 72 movw %ax, %ds 73 movw %ax, %gs 74 movw %ax, %es 75 movw %ax, %ss 76 77 /* Clear the interrupt vectors */ 78 lidt blank_idt_ptr 79 80 /* Early platform init (setup gpio, etc ) */ 81 jmp early_board_init 82.globl early_board_init_ret 83early_board_init_ret: 84 85 /* Initialise Cache-As-RAM */ 86 jmp car_init 87.globl car_init_ret 88car_init_ret: 89 /* 90 * We now have CONFIG_SYS_CAR_SIZE bytes of Cache-As-RAM (or SRAM, 91 * or fully initialised SDRAM - we really don't care which) 92 * starting at CONFIG_SYS_CAR_ADDR to be used as a temporary stack 93 */ 94 95 /* Stack grows down from top of CAR */ 96 movl $(CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE), %esp 97 98 /* Reserve space on stack for global data */ 99 subl $GENERATED_GBL_DATA_SIZE, %esp 100 101 /* Align global data to 16-byte boundary */ 102 andl $0xfffffff0, %esp 103 104 /* Setup first parameter to setup_gdt */ 105 movl %esp, %eax 106 107 /* Reserve space for global descriptor table */ 108 subl $X86_GDT_SIZE, %esp 109 110 /* Align temporary global descriptor table to 16-byte boundary */ 111 andl $0xfffffff0, %esp 112 113 /* Set second parameter to setup_gdt */ 114 movl %esp, %edx 115 116 /* gd->gd_addr = gd (Required to allow gd->xyz to work) */ 117 movl %eax, (%eax) 118 119 /* Setup global descriptor table so gd->xyz works */ 120 call setup_gdt 121 122 /* Set parameter to board_init_f() to boot flags */ 123 xorl %eax, %eax 124 movw %bx, %ax 125 126 /* Enter, U-boot! */ 127 call board_init_f 128 129 /* indicate (lack of) progress */ 130 movw $0x85, %ax 131 jmp die 132 133.globl board_init_f_r_trampoline 134.type board_init_f_r_trampoline, @function 135board_init_f_r_trampoline: 136 /* 137 * SDRAM has been initialised, U-Boot code has been copied into 138 * RAM, BSS has been cleared and relocation adjustments have been 139 * made. It is now time to jump into the in-RAM copy of U-Boot 140 * 141 * %eax = Address of top of new stack 142 */ 143 144 /* Stack grows down from top of SDRAM */ 145 movl %eax, %esp 146 147 /* Reserve space on stack for global data */ 148 subl $GENERATED_GBL_DATA_SIZE, %esp 149 150 /* Align global data to 16-byte boundary */ 151 andl $0xfffffff0, %esp 152 153 /* Setup first parameter to memcpy (and setup_gdt) */ 154 movl %esp, %eax 155 156 /* Setup second parameter to memcpy */ 157 fs movl 0, %edx 158 159 /* Set third parameter to memcpy */ 160 movl $GENERATED_GBL_DATA_SIZE, %ecx 161 162 /* Copy global data from CAR to SDRAM stack */ 163 call memcpy 164 165 /* Reserve space for global descriptor table */ 166 subl $X86_GDT_SIZE, %esp 167 168 /* Align global descriptor table to 16-byte boundary */ 169 andl $0xfffffff0, %esp 170 171 /* Set second parameter to setup_gdt */ 172 movl %esp, %edx 173 174 /* gd->gd_addr = gd (Required to allow gd->xyz to work) */ 175 movl %eax, (%eax) 176 177 /* Setup global descriptor table so gd->xyz works */ 178 call setup_gdt 179 180 /* Re-enter U-Boot by calling board_init_f_r */ 181 call board_init_f_r 182 183die: 184 hlt 185 jmp die 186 hlt 187 188blank_idt_ptr: 189 .word 0 /* limit */ 190 .long 0 /* base */ 191 192 .p2align 2 /* force 4-byte alignment */ 193 194multiboot_header: 195 /* magic */ 196 .long 0x1BADB002 197 /* flags */ 198 .long (1 << 16) 199 /* checksum */ 200 .long -0x1BADB002 - (1 << 16) 201 /* header addr */ 202 .long multiboot_header - _x86boot_start + CONFIG_SYS_TEXT_BASE 203 /* load addr */ 204 .long CONFIG_SYS_TEXT_BASE 205 /* load end addr */ 206 .long 0 207 /* bss end addr */ 208 .long 0 209 /* entry addr */ 210 .long CONFIG_SYS_TEXT_BASE 211