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 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. The 29 * following code is not executed from a cold-reset (actually, a 30 * lot of it is, but from real-mode after cold reset. It is 31 * repeated here to put the board into a state as close to cold 32 * reset as necessary) 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 movw $GD_FLG_WARM_BOOT, %bx 45 jmp 1f 46_start: 47 /* 48 * This is the 32-bit cold-reset entry point. Initialize %bx to 0 49 * in case we're preceeded by some sort of boot stub. 50 */ 51 movw $GD_FLG_COLD_BOOT, %bx 521: 53 /* Save BIST */ 54 movl %eax, %ebp 55 56 /* Load the segement registes to match the gdt loaded in start16.S */ 57 movl $(X86_GDT_ENTRY_32BIT_DS * X86_GDT_ENTRY_SIZE), %eax 58 movw %ax, %fs 59 movw %ax, %ds 60 movw %ax, %gs 61 movw %ax, %es 62 movw %ax, %ss 63 64 /* Clear the interrupt vectors */ 65 lidt blank_idt_ptr 66 67 /* Early platform init (setup gpio, etc ) */ 68 jmp early_board_init 69.globl early_board_init_ret 70early_board_init_ret: 71 post_code(POST_START) 72 73 /* Initialise Cache-As-RAM */ 74 jmp car_init 75.globl car_init_ret 76car_init_ret: 77 /* 78 * We now have CONFIG_SYS_CAR_SIZE bytes of Cache-As-RAM (or SRAM, 79 * or fully initialised SDRAM - we really don't care which) 80 * starting at CONFIG_SYS_CAR_ADDR to be used as a temporary stack 81 * and early malloc area. 82 * 83 * Stack grows down from top of CAR. We have: 84 * 85 * top-> CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE 86 * global_data 87 * x86 global descriptor table 88 * early malloc area 89 * stack 90 * bottom-> CONFIG_SYS_CAR_ADDR 91 */ 92 93 /* Stack grows down from top of CAR */ 94 movl $(CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE), %esp 95 96 /* Reserve space on stack for global data */ 97 subl $GENERATED_GBL_DATA_SIZE, %esp 98 99 /* Align global data to 16-byte boundary */ 100 andl $0xfffffff0, %esp 101 post_code(POST_START_STACK) 102 103 /* Zero the global data since it won't happen later */ 104 xorl %eax, %eax 105 movl $GENERATED_GBL_DATA_SIZE, %ecx 106 movl %esp, %edi 107 rep stosb 108 109 /* Setup first parameter to setup_gdt, pointer to global_data */ 110 movl %esp, %eax 111 112 /* Reserve space for global descriptor table */ 113 subl $X86_GDT_SIZE, %esp 114 115 /* Align temporary global descriptor table to 16-byte boundary */ 116 andl $0xfffffff0, %esp 117 movl %esp, %ecx 118 119#if defined(CONFIG_SYS_MALLOC_F_LEN) 120 subl $CONFIG_SYS_MALLOC_F_LEN, %esp 121 movl %eax, %edx 122 addl $GD_MALLOC_BASE, %edx 123 movl %esp, (%edx) 124#endif 125 /* Store BIST */ 126 movl %eax, %edx 127 addl $GD_BIST, %edx 128 movl %ebp, (%edx) 129 130 /* Set second parameter to setup_gdt */ 131 movl %ecx, %edx 132 133 /* Setup global descriptor table so gd->xyz works */ 134 call setup_gdt 135 136 /* Set parameter to board_init_f() to boot flags */ 137 post_code(POST_START_DONE) 138 xorl %eax, %eax 139 140 /* Enter, U-boot! */ 141 call board_init_f 142 143 /* indicate (lack of) progress */ 144 movw $0x85, %ax 145 jmp die 146 147.globl board_init_f_r_trampoline 148.type board_init_f_r_trampoline, @function 149board_init_f_r_trampoline: 150 /* 151 * SDRAM has been initialised, U-Boot code has been copied into 152 * RAM, BSS has been cleared and relocation adjustments have been 153 * made. It is now time to jump into the in-RAM copy of U-Boot 154 * 155 * %eax = Address of top of new stack 156 */ 157 158 /* Stack grows down from top of SDRAM */ 159 movl %eax, %esp 160 161 /* Reserve space on stack for global data */ 162 subl $GENERATED_GBL_DATA_SIZE, %esp 163 164 /* Align global data to 16-byte boundary */ 165 andl $0xfffffff0, %esp 166 167 /* Setup first parameter to memcpy (and setup_gdt) */ 168 movl %esp, %eax 169 170 /* Setup second parameter to memcpy */ 171 fs movl 0, %edx 172 173 /* Set third parameter to memcpy */ 174 movl $GENERATED_GBL_DATA_SIZE, %ecx 175 176 /* Copy global data from CAR to SDRAM stack */ 177 call memcpy 178 179 /* Reserve space for global descriptor table */ 180 subl $X86_GDT_SIZE, %esp 181 182 /* Align global descriptor table to 16-byte boundary */ 183 andl $0xfffffff0, %esp 184 185 /* Set second parameter to setup_gdt */ 186 movl %esp, %edx 187 188 /* Setup global descriptor table so gd->xyz works */ 189 call setup_gdt 190 191 /* Re-enter U-Boot by calling board_init_f_r */ 192 call board_init_f_r 193 194die: 195 hlt 196 jmp die 197 hlt 198 199blank_idt_ptr: 200 .word 0 /* limit */ 201 .long 0 /* base */ 202 203 .p2align 2 /* force 4-byte alignment */ 204 205multiboot_header: 206 /* magic */ 207 .long 0x1BADB002 208 /* flags */ 209 .long (1 << 16) 210 /* checksum */ 211 .long -0x1BADB002 - (1 << 16) 212 /* header addr */ 213 .long multiboot_header - _x86boot_start + CONFIG_SYS_TEXT_BASE 214 /* load addr */ 215 .long CONFIG_SYS_TEXT_BASE 216 /* load end addr */ 217 .long 0 218 /* bss end addr */ 219 .long 0 220 /* entry addr */ 221 .long CONFIG_SYS_TEXT_BASE 222