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 movw $GD_FLG_WARM_BOOT, %bx 45 jmp 1f 46_start: 47 /* 48 * This is the 32-bit cold-reset entry point, coming from start16. 49 * Set %bx to 0 to indicate this. 50 */ 51 movw $GD_FLG_COLD_BOOT, %bx 521: 53 /* Save BIST */ 54 movl %eax, %ebp 55 56 /* Load the segement registers 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 /* 68 * Critical early platform init - generally not used, we prefer init 69 * to happen later when we have a console, in case something goes 70 * wrong. 71 */ 72 jmp early_board_init 73.globl early_board_init_ret 74early_board_init_ret: 75 post_code(POST_START) 76 77 /* Initialise Cache-As-RAM */ 78 jmp car_init 79.globl car_init_ret 80car_init_ret: 81#ifndef CONFIG_HAVE_FSP 82 /* 83 * We now have CONFIG_SYS_CAR_SIZE bytes of Cache-As-RAM (or SRAM, 84 * or fully initialised SDRAM - we really don't care which) 85 * starting at CONFIG_SYS_CAR_ADDR to be used as a temporary stack 86 * and early malloc() area. The MRC requires some space at the top. 87 * 88 * Stack grows down from top of CAR. We have: 89 * 90 * top-> CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE 91 * MRC area 92 * global_data 93 * x86 global descriptor table 94 * early malloc area 95 * stack 96 * bottom-> CONFIG_SYS_CAR_ADDR 97 */ 98 movl $(CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE - 4), %esp 99#ifdef CONFIG_DCACHE_RAM_MRC_VAR_SIZE 100 subl $CONFIG_DCACHE_RAM_MRC_VAR_SIZE, %esp 101#endif 102#else 103 /* 104 * When we get here after car_init(), esp points to a temporary stack 105 * and esi holds the HOB list address returned by the FSP. 106 */ 107#endif 108 109 /* Reserve space on stack for global data */ 110 subl $GENERATED_GBL_DATA_SIZE, %esp 111 112 /* Align global data to 16-byte boundary */ 113 andl $0xfffffff0, %esp 114 post_code(POST_START_STACK) 115 116 /* Zero the global data since it won't happen later */ 117 xorl %eax, %eax 118 movl $GENERATED_GBL_DATA_SIZE, %ecx 119 movl %esp, %edi 120 rep stosb 121 122#ifdef CONFIG_HAVE_FSP 123 test %esi, %esi 124 jz skip_hob 125 126 /* Store HOB list */ 127 movl %esp, %edx 128 addl $GD_HOB_LIST, %edx 129 movl %esi, (%edx) 130 131skip_hob: 132#endif 133 /* Setup first parameter to setup_gdt, pointer to global_data */ 134 movl %esp, %eax 135 136 /* Reserve space for global descriptor table */ 137 subl $X86_GDT_SIZE, %esp 138 139 /* Align temporary global descriptor table to 16-byte boundary */ 140 andl $0xfffffff0, %esp 141 movl %esp, %ecx 142 143#if defined(CONFIG_SYS_MALLOC_F_LEN) 144 /* Set up the pre-relocation malloc pool */ 145 subl $CONFIG_SYS_MALLOC_F_LEN, %esp 146 movl %eax, %edx 147 addl $GD_MALLOC_BASE, %edx 148 movl %esp, (%edx) 149#endif 150 /* Store BIST into global_data */ 151 movl %eax, %edx 152 addl $GD_BIST, %edx 153 movl %ebp, (%edx) 154 155 /* Set second parameter to setup_gdt() */ 156 movl %ecx, %edx 157 158 /* Setup global descriptor table so gd->xyz works */ 159 call setup_gdt 160 161 /* Set parameter to board_init_f() to boot flags */ 162 post_code(POST_START_DONE) 163 xorl %eax, %eax 164 165 /* Enter, U-Boot! */ 166 call board_init_f 167 168 /* indicate (lack of) progress */ 169 movw $0x85, %ax 170 jmp die 171 172.globl board_init_f_r_trampoline 173.type board_init_f_r_trampoline, @function 174board_init_f_r_trampoline: 175 /* 176 * SDRAM has been initialised, U-Boot code has been copied into 177 * RAM, BSS has been cleared and relocation adjustments have been 178 * made. It is now time to jump into the in-RAM copy of U-Boot 179 * 180 * %eax = Address of top of new stack 181 */ 182 183 /* Stack grows down from top of SDRAM */ 184 movl %eax, %esp 185 186 /* Reserve space on stack for global data */ 187 subl $GENERATED_GBL_DATA_SIZE, %esp 188 189 /* Align global data to 16-byte boundary */ 190 andl $0xfffffff0, %esp 191 192 /* Setup first parameter to memcpy() and setup_gdt() */ 193 movl %esp, %eax 194 195 /* Setup second parameter to memcpy() */ 196 fs movl 0, %edx 197 198 /* Set third parameter to memcpy() */ 199 movl $GENERATED_GBL_DATA_SIZE, %ecx 200 201 /* Copy global data from CAR to SDRAM stack */ 202 call memcpy 203 204 /* Reserve space for global descriptor table */ 205 subl $X86_GDT_SIZE, %esp 206 207 /* Align global descriptor table to 16-byte boundary */ 208 andl $0xfffffff0, %esp 209 210 /* Set second parameter to setup_gdt() */ 211 movl %esp, %edx 212 213 /* Setup global descriptor table so gd->xyz works */ 214 call setup_gdt 215 216 /* Set if we need to disable CAR */ 217.weak car_uninit 218 movl $car_uninit, %eax 219 cmpl $0, %eax 220 jz 1f 221 222 call car_uninit 2231: 224 /* Re-enter U-Boot by calling board_init_f_r() */ 225 call board_init_f_r 226 227die: 228 hlt 229 jmp die 230 hlt 231 232blank_idt_ptr: 233 .word 0 /* limit */ 234 .long 0 /* base */ 235 236 .p2align 2 /* force 4-byte alignment */ 237 238 /* Add a multiboot header so U-Boot can be loaded by GRUB2 */ 239multiboot_header: 240 /* magic */ 241 .long 0x1badb002 242 /* flags */ 243 .long (1 << 16) 244 /* checksum */ 245 .long -0x1BADB002 - (1 << 16) 246 /* header addr */ 247 .long multiboot_header - _x86boot_start + CONFIG_SYS_TEXT_BASE 248 /* load addr */ 249 .long CONFIG_SYS_TEXT_BASE 250 /* load end addr */ 251 .long 0 252 /* bss end addr */ 253 .long 0 254 /* entry addr */ 255 .long CONFIG_SYS_TEXT_BASE 256