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 <version.h> 15#include <asm/global_data.h> 16#include <asm/post.h> 17#include <asm/processor.h> 18#include <asm/processor-flags.h> 19#include <generated/generic-asm-offsets.h> 20#include <generated/asm-offsets.h> 21 22.section .text 23.code32 24.globl _start 25.type _start, @function 26.globl _x86boot_start 27_x86boot_start: 28 /* 29 * This is the fail safe 32-bit bootstrap entry point. The 30 * following code is not executed from a cold-reset (actually, a 31 * lot of it is, but from real-mode after cold reset. It is 32 * repeated here to put the board into a state as close to cold 33 * reset as necessary) 34 */ 35 cli 36 cld 37 38 /* Turn off cache (this might require a 486-class CPU) */ 39 movl %cr0, %eax 40 orl $(X86_CR0_NW | X86_CR0_CD), %eax 41 movl %eax, %cr0 42 wbinvd 43 44 /* Tell 32-bit code it is being entered from an in-RAM copy */ 45 movw $GD_FLG_WARM_BOOT, %bx 46 jmp 1f 47_start: 48 /* 49 * This is the 32-bit cold-reset entry point. Initialize %bx to 0 50 * in case we're preceeded by some sort of boot stub. 51 */ 52 movw $GD_FLG_COLD_BOOT, %bx 531: 54 /* Save BIST */ 55 movl %eax, %ebp 56 57 /* Load the segement registes to match the gdt loaded in start16.S */ 58 movl $(X86_GDT_ENTRY_32BIT_DS * X86_GDT_ENTRY_SIZE), %eax 59 movw %ax, %fs 60 movw %ax, %ds 61 movw %ax, %gs 62 movw %ax, %es 63 movw %ax, %ss 64 65 /* Clear the interrupt vectors */ 66 lidt blank_idt_ptr 67 68 /* Early platform init (setup gpio, etc ) */ 69 jmp early_board_init 70.globl early_board_init_ret 71early_board_init_ret: 72 post_code(POST_START) 73 74 /* Initialise Cache-As-RAM */ 75 jmp car_init 76.globl car_init_ret 77car_init_ret: 78 /* 79 * We now have CONFIG_SYS_CAR_SIZE bytes of Cache-As-RAM (or SRAM, 80 * or fully initialised SDRAM - we really don't care which) 81 * starting at CONFIG_SYS_CAR_ADDR to be used as a temporary stack 82 * and early malloc area. The MRC requires some space at the top. 83 * 84 * Stack grows down from top of CAR. We have: 85 * 86 * top-> CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE 87 * MRC area 88 * global_data 89 * x86 global descriptor table 90 * early malloc area 91 * stack 92 * bottom-> CONFIG_SYS_CAR_ADDR 93 */ 94 movl $(CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE - 4), %esp 95#ifdef CONFIG_DCACHE_RAM_MRC_VAR_SIZE 96 subl $CONFIG_DCACHE_RAM_MRC_VAR_SIZE, %esp 97#endif 98 99 /* Reserve space on stack for global data */ 100 subl $GENERATED_GBL_DATA_SIZE, %esp 101 102 /* Align global data to 16-byte boundary */ 103 andl $0xfffffff0, %esp 104 post_code(POST_START_STACK) 105 106 /* Zero the global data since it won't happen later */ 107 xorl %eax, %eax 108 movl $GENERATED_GBL_DATA_SIZE, %ecx 109 movl %esp, %edi 110 rep stosb 111 112 /* Setup first parameter to setup_gdt, pointer to global_data */ 113 movl %esp, %eax 114 115 /* Reserve space for global descriptor table */ 116 subl $X86_GDT_SIZE, %esp 117 118 /* Align temporary global descriptor table to 16-byte boundary */ 119 andl $0xfffffff0, %esp 120 movl %esp, %ecx 121 122#if defined(CONFIG_SYS_MALLOC_F_LEN) 123 subl $CONFIG_SYS_MALLOC_F_LEN, %esp 124 movl %eax, %edx 125 addl $GD_MALLOC_BASE, %edx 126 movl %esp, (%edx) 127#endif 128 /* Store BIST */ 129 movl %eax, %edx 130 addl $GD_BIST, %edx 131 movl %ebp, (%edx) 132 133 /* Set second parameter to setup_gdt */ 134 movl %ecx, %edx 135 136 /* Setup global descriptor table so gd->xyz works */ 137 call setup_gdt 138 139 /* Set parameter to board_init_f() to boot flags */ 140 post_code(POST_START_DONE) 141 xorl %eax, %eax 142 143 /* Enter, U-boot! */ 144 call board_init_f 145 146 /* indicate (lack of) progress */ 147 movw $0x85, %ax 148 jmp die 149 150.globl board_init_f_r_trampoline 151.type board_init_f_r_trampoline, @function 152board_init_f_r_trampoline: 153 /* 154 * SDRAM has been initialised, U-Boot code has been copied into 155 * RAM, BSS has been cleared and relocation adjustments have been 156 * made. It is now time to jump into the in-RAM copy of U-Boot 157 * 158 * %eax = Address of top of new stack 159 */ 160 161 /* Stack grows down from top of SDRAM */ 162 movl %eax, %esp 163 164 /* Reserve space on stack for global data */ 165 subl $GENERATED_GBL_DATA_SIZE, %esp 166 167 /* Align global data to 16-byte boundary */ 168 andl $0xfffffff0, %esp 169 170 /* Setup first parameter to memcpy (and setup_gdt) */ 171 movl %esp, %eax 172 173 /* Setup second parameter to memcpy */ 174 fs movl 0, %edx 175 176 /* Set third parameter to memcpy */ 177 movl $GENERATED_GBL_DATA_SIZE, %ecx 178 179 /* Copy global data from CAR to SDRAM stack */ 180 call memcpy 181 182 /* Reserve space for global descriptor table */ 183 subl $X86_GDT_SIZE, %esp 184 185 /* Align global descriptor table to 16-byte boundary */ 186 andl $0xfffffff0, %esp 187 188 /* Set second parameter to setup_gdt */ 189 movl %esp, %edx 190 191 /* Setup global descriptor table so gd->xyz works */ 192 call setup_gdt 193 194 /* Re-enter U-Boot by calling board_init_f_r */ 195 call board_init_f_r 196 197die: 198 hlt 199 jmp die 200 hlt 201 202blank_idt_ptr: 203 .word 0 /* limit */ 204 .long 0 /* base */ 205 206 .p2align 2 /* force 4-byte alignment */ 207 208multiboot_header: 209 /* magic */ 210 .long 0x1BADB002 211 /* flags */ 212 .long (1 << 16) 213 /* checksum */ 214 .long -0x1BADB002 - (1 << 16) 215 /* header addr */ 216 .long multiboot_header - _x86boot_start + CONFIG_SYS_TEXT_BASE 217 /* load addr */ 218 .long CONFIG_SYS_TEXT_BASE 219 /* load end addr */ 220 .long 0 221 /* bss end addr */ 222 .long 0 223 /* entry addr */ 224 .long CONFIG_SYS_TEXT_BASE 225