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 * SPDX-License-Identifier: GPL-2.0+ 11 */ 12 13#include <config.h> 14#include <asm/global_data.h> 15#include <asm/post.h> 16#include <asm/processor.h> 17#include <asm/processor-flags.h> 18#include <generated/generic-asm-offsets.h> 19#include <generated/asm-offsets.h> 20 21.section .text 22.code32 23.globl _start 24.type _start, @function 25.globl _x86boot_start 26_x86boot_start: 27 /* 28 * This is the fail-safe 32-bit bootstrap entry point. 29 * 30 * This code is used when booting from another boot loader like 31 * coreboot or EFI. So we repeat some of the same init found in 32 * start16. 33 */ 34 cli 35 cld 36 37 /* Turn off cache (this might require a 486-class CPU) */ 38 movl %cr0, %eax 39 orl $(X86_CR0_NW | X86_CR0_CD), %eax 40 movl %eax, %cr0 41 wbinvd 42 43 /* Tell 32-bit code it is being entered from an in-RAM copy */ 44 movl $GD_FLG_WARM_BOOT, %ebx 45 46 /* 47 * Zero the BIST (Built-In Self Test) value since we don't have it. 48 * It must be 0 or the previous loader would have reported an error. 49 */ 50 movl $0, %ebp 51 52 jmp 1f 53 54 /* Add a way for tools to discover the _start entry point */ 55 .align 4 56 .long 0x12345678 57_start: 58 /* 59 * This is the 32-bit cold-reset entry point, coming from start16. 60 * Set %ebx to GD_FLG_COLD_BOOT to indicate this. 61 */ 62 movl $GD_FLG_COLD_BOOT, %ebx 63 64 /* Save BIST */ 65 movl %eax, %ebp 661: 67 68 /* Save table pointer */ 69 movl %ecx, %esi 70 71 /* Load the segement registers to match the GDT loaded in start16.S */ 72 movl $(X86_GDT_ENTRY_32BIT_DS * X86_GDT_ENTRY_SIZE), %eax 73 movw %ax, %fs 74 movw %ax, %ds 75 movw %ax, %gs 76 movw %ax, %es 77 movw %ax, %ss 78 79 /* Clear the interrupt vectors */ 80 lidt blank_idt_ptr 81 82 /* 83 * Critical early platform init - generally not used, we prefer init 84 * to happen later when we have a console, in case something goes 85 * wrong. 86 */ 87 jmp early_board_init 88.globl early_board_init_ret 89early_board_init_ret: 90 post_code(POST_START) 91 92 /* Initialise Cache-As-RAM */ 93 jmp car_init 94.globl car_init_ret 95car_init_ret: 96#ifndef CONFIG_HAVE_FSP 97 /* 98 * We now have CONFIG_SYS_CAR_SIZE bytes of Cache-As-RAM (or SRAM, 99 * or fully initialised SDRAM - we really don't care which) 100 * starting at CONFIG_SYS_CAR_ADDR to be used as a temporary stack 101 * and early malloc() area. The MRC requires some space at the top. 102 * 103 * Stack grows down from top of CAR. We have: 104 * 105 * top-> CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE 106 * MRC area 107 * global_data with x86 global descriptor table 108 * early malloc area 109 * stack 110 * bottom-> CONFIG_SYS_CAR_ADDR 111 */ 112 movl $(CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE - 4), %esp 113#ifdef CONFIG_DCACHE_RAM_MRC_VAR_SIZE 114 subl $CONFIG_DCACHE_RAM_MRC_VAR_SIZE, %esp 115#endif 116#else 117 /* 118 * U-Boot enters here twice. For the first time it comes from 119 * car_init_done() with esp points to a temporary stack and esi 120 * set to zero. For the second time it comes from fsp_init_done() 121 * with esi holding the HOB list address returned by the FSP. 122 */ 123#endif 124 /* Set up global data */ 125 mov %esp, %eax 126 call board_init_f_mem 127 mov %eax, %esp 128 129 /* 130 * Debug UART is available here although it may not be plumbed out 131 * to pins depending on the board. To use it: 132 * 133 * call debug_uart_init 134 * mov $'a', %eax 135 * call printch 136 */ 137 138 /* Get address of global_data */ 139 mov %fs:0, %edx 140#ifdef CONFIG_HAVE_FSP 141 /* Store the HOB list if we have one */ 142 test %esi, %esi 143 jz skip_hob 144 movl %esi, GD_HOB_LIST(%edx) 145 146 /* 147 * After fsp_init() returns, the stack has already been switched to a 148 * place within system memory as defined by CONFIG_FSP_TEMP_RAM_ADDR. 149 * Enlarge the size of malloc() pool before relocation since we have 150 * plenty of memory now. 151 */ 152 subl $CONFIG_FSP_SYS_MALLOC_F_LEN, %esp 153 movl %esp, GD_MALLOC_BASE(%edx) 154skip_hob: 155#else 156 /* Store table pointer */ 157 movl %esi, GD_TABLE(%edx) 158#endif 159 /* Store BIST */ 160 movl %ebp, GD_BIST(%edx) 161 162 /* Set parameter to board_init_f() to boot flags */ 163 post_code(POST_START_DONE) 164 xorl %eax, %eax 165 166 /* Enter, U-Boot! */ 167 call board_init_f 168 169 /* indicate (lack of) progress */ 170 movw $0x85, %ax 171 jmp die 172 173.globl board_init_f_r_trampoline 174.type board_init_f_r_trampoline, @function 175board_init_f_r_trampoline: 176 /* 177 * SDRAM has been initialised, U-Boot code has been copied into 178 * RAM, BSS has been cleared and relocation adjustments have been 179 * made. It is now time to jump into the in-RAM copy of U-Boot 180 * 181 * %eax = Address of top of new stack 182 */ 183 184 /* Stack grows down from top of SDRAM */ 185 movl %eax, %esp 186 187 /* See if we need to disable CAR */ 188.weak car_uninit 189 movl $car_uninit, %eax 190 cmpl $0, %eax 191 jz 1f 192 193 call car_uninit 1941: 195 /* Re-enter U-Boot by calling board_init_f_r() */ 196 call board_init_f_r 197 198die: 199 hlt 200 jmp die 201 hlt 202 203blank_idt_ptr: 204 .word 0 /* limit */ 205 .long 0 /* base */ 206 207 .p2align 2 /* force 4-byte alignment */ 208 209 /* Add a multiboot header so U-Boot can be loaded by GRUB2 */ 210multiboot_header: 211 /* magic */ 212 .long 0x1badb002 213 /* flags */ 214 .long (1 << 16) 215 /* checksum */ 216 .long -0x1BADB002 - (1 << 16) 217 /* header addr */ 218 .long multiboot_header - _x86boot_start + CONFIG_SYS_TEXT_BASE 219 /* load addr */ 220 .long CONFIG_SYS_TEXT_BASE 221 /* load end addr */ 222 .long 0 223 /* bss end addr */ 224 .long 0 225 /* entry addr */ 226 .long CONFIG_SYS_TEXT_BASE 227