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. The MRC requires some space at the top. 82 * 83 * Stack grows down from top of CAR. We have: 84 * 85 * top-> CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE 86 * MRC area 87 * global_data 88 * x86 global descriptor table 89 * early malloc area 90 * stack 91 * bottom-> CONFIG_SYS_CAR_ADDR 92 */ 93 movl $(CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE - 4), %esp 94#ifdef CONFIG_DCACHE_RAM_MRC_VAR_SIZE 95 subl $CONFIG_DCACHE_RAM_MRC_VAR_SIZE, %esp 96#endif 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 post_code(POST_START_STACK) 104 105 /* Zero the global data since it won't happen later */ 106 xorl %eax, %eax 107 movl $GENERATED_GBL_DATA_SIZE, %ecx 108 movl %esp, %edi 109 rep stosb 110 111 /* Setup first parameter to setup_gdt, pointer to global_data */ 112 movl %esp, %eax 113 114 /* Reserve space for global descriptor table */ 115 subl $X86_GDT_SIZE, %esp 116 117 /* Align temporary global descriptor table to 16-byte boundary */ 118 andl $0xfffffff0, %esp 119 movl %esp, %ecx 120 121#if defined(CONFIG_SYS_MALLOC_F_LEN) 122 subl $CONFIG_SYS_MALLOC_F_LEN, %esp 123 movl %eax, %edx 124 addl $GD_MALLOC_BASE, %edx 125 movl %esp, (%edx) 126#endif 127 /* Store BIST */ 128 movl %eax, %edx 129 addl $GD_BIST, %edx 130 movl %ebp, (%edx) 131 132 /* Set second parameter to setup_gdt */ 133 movl %ecx, %edx 134 135 /* Setup global descriptor table so gd->xyz works */ 136 call setup_gdt 137 138 /* Set parameter to board_init_f() to boot flags */ 139 post_code(POST_START_DONE) 140 xorl %eax, %eax 141 142 /* Enter, U-boot! */ 143 call board_init_f 144 145 /* indicate (lack of) progress */ 146 movw $0x85, %ax 147 jmp die 148 149.globl board_init_f_r_trampoline 150.type board_init_f_r_trampoline, @function 151board_init_f_r_trampoline: 152 /* 153 * SDRAM has been initialised, U-Boot code has been copied into 154 * RAM, BSS has been cleared and relocation adjustments have been 155 * made. It is now time to jump into the in-RAM copy of U-Boot 156 * 157 * %eax = Address of top of new stack 158 */ 159 160 /* Stack grows down from top of SDRAM */ 161 movl %eax, %esp 162 163 /* Reserve space on stack for global data */ 164 subl $GENERATED_GBL_DATA_SIZE, %esp 165 166 /* Align global data to 16-byte boundary */ 167 andl $0xfffffff0, %esp 168 169 /* Setup first parameter to memcpy (and setup_gdt) */ 170 movl %esp, %eax 171 172 /* Setup second parameter to memcpy */ 173 fs movl 0, %edx 174 175 /* Set third parameter to memcpy */ 176 movl $GENERATED_GBL_DATA_SIZE, %ecx 177 178 /* Copy global data from CAR to SDRAM stack */ 179 call memcpy 180 181 /* Reserve space for global descriptor table */ 182 subl $X86_GDT_SIZE, %esp 183 184 /* Align global descriptor table to 16-byte boundary */ 185 andl $0xfffffff0, %esp 186 187 /* Set second parameter to setup_gdt */ 188 movl %esp, %edx 189 190 /* Setup global descriptor table so gd->xyz works */ 191 call setup_gdt 192 193 /* Re-enter U-Boot by calling board_init_f_r */ 194 call board_init_f_r 195 196die: 197 hlt 198 jmp die 199 hlt 200 201blank_idt_ptr: 202 .word 0 /* limit */ 203 .long 0 /* base */ 204 205 .p2align 2 /* force 4-byte alignment */ 206 207multiboot_header: 208 /* magic */ 209 .long 0x1BADB002 210 /* flags */ 211 .long (1 << 16) 212 /* checksum */ 213 .long -0x1BADB002 - (1 << 16) 214 /* header addr */ 215 .long multiboot_header - _x86boot_start + CONFIG_SYS_TEXT_BASE 216 /* load addr */ 217 .long CONFIG_SYS_TEXT_BASE 218 /* load end addr */ 219 .long 0 220 /* bss end addr */ 221 .long 0 222 /* entry addr */ 223 .long CONFIG_SYS_TEXT_BASE 224