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#ifdef CONFIG_X86_LOAD_FROM_32_BIT 72 lgdt gdt_ptr2 73#endif 74 75 /* Load the segement registers to match the GDT loaded in start16.S */ 76 movl $(X86_GDT_ENTRY_32BIT_DS * X86_GDT_ENTRY_SIZE), %eax 77 movw %ax, %fs 78 movw %ax, %ds 79 movw %ax, %gs 80 movw %ax, %es 81 movw %ax, %ss 82 83 /* Clear the interrupt vectors */ 84 lidt blank_idt_ptr 85 86 /* 87 * Critical early platform init - generally not used, we prefer init 88 * to happen later when we have a console, in case something goes 89 * wrong. 90 */ 91 jmp early_board_init 92.globl early_board_init_ret 93early_board_init_ret: 94 post_code(POST_START) 95 96 /* Initialise Cache-As-RAM */ 97 jmp car_init 98.globl car_init_ret 99car_init_ret: 100#ifndef CONFIG_HAVE_FSP 101 /* 102 * We now have CONFIG_SYS_CAR_SIZE bytes of Cache-As-RAM (or SRAM, 103 * or fully initialised SDRAM - we really don't care which) 104 * starting at CONFIG_SYS_CAR_ADDR to be used as a temporary stack 105 * and early malloc() area. The MRC requires some space at the top. 106 * 107 * Stack grows down from top of CAR. We have: 108 * 109 * top-> CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE 110 * MRC area 111 * global_data with x86 global descriptor table 112 * early malloc area 113 * stack 114 * bottom-> CONFIG_SYS_CAR_ADDR 115 */ 116 movl $(CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE - 4), %esp 117#ifdef CONFIG_DCACHE_RAM_MRC_VAR_SIZE 118 subl $CONFIG_DCACHE_RAM_MRC_VAR_SIZE, %esp 119#endif 120#else 121 /* 122 * U-Boot enters here twice. For the first time it comes from 123 * car_init_done() with esp points to a temporary stack and esi 124 * set to zero. For the second time it comes from fsp_init_done() 125 * with esi holding the HOB list address returned by the FSP. 126 */ 127#endif 128 /* Set up global data */ 129 mov %esp, %eax 130 call board_init_f_alloc_reserve 131 mov %eax, %esp 132 call board_init_f_init_reserve 133 134#ifdef CONFIG_DEBUG_UART 135 call debug_uart_init 136#endif 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 227 228#ifdef CONFIG_X86_LOAD_FROM_32_BIT 229 /* 230 * The following Global Descriptor Table is just enough to get us into 231 * 'Flat Protected Mode' - It will be discarded as soon as the final 232 * GDT is setup in a safe location in RAM 233 */ 234gdt_ptr2: 235 .word 0x1f /* limit (31 bytes = 4 GDT entries - 1) */ 236 .long gdt_rom2 /* base */ 237 238 /* Some CPUs are picky about GDT alignment... */ 239 .align 16 240.globl gdt_rom2 241gdt_rom2: 242 /* 243 * The GDT table ... 244 * 245 * Selector Type 246 * 0x00 NULL 247 * 0x08 Unused 248 * 0x10 32bit code 249 * 0x18 32bit data/stack 250 */ 251 /* The NULL Desciptor - Mandatory */ 252 .word 0x0000 /* limit_low */ 253 .word 0x0000 /* base_low */ 254 .byte 0x00 /* base_middle */ 255 .byte 0x00 /* access */ 256 .byte 0x00 /* flags + limit_high */ 257 .byte 0x00 /* base_high */ 258 259 /* Unused Desciptor - (matches Linux) */ 260 .word 0x0000 /* limit_low */ 261 .word 0x0000 /* base_low */ 262 .byte 0x00 /* base_middle */ 263 .byte 0x00 /* access */ 264 .byte 0x00 /* flags + limit_high */ 265 .byte 0x00 /* base_high */ 266 267 /* 268 * The Code Segment Descriptor: 269 * - Base = 0x00000000 270 * - Size = 4GB 271 * - Access = Present, Ring 0, Exec (Code), Readable 272 * - Flags = 4kB Granularity, 32-bit 273 */ 274 .word 0xffff /* limit_low */ 275 .word 0x0000 /* base_low */ 276 .byte 0x00 /* base_middle */ 277 .byte 0x9b /* access */ 278 .byte 0xcf /* flags + limit_high */ 279 .byte 0x00 /* base_high */ 280 281 /* 282 * The Data Segment Descriptor: 283 * - Base = 0x00000000 284 * - Size = 4GB 285 * - Access = Present, Ring 0, Non-Exec (Data), Writable 286 * - Flags = 4kB Granularity, 32-bit 287 */ 288 .word 0xffff /* limit_low */ 289 .word 0x0000 /* base_low */ 290 .byte 0x00 /* base_middle */ 291 .byte 0x93 /* access */ 292 .byte 0xcf /* flags + limit_high */ 293 .byte 0x00 /* base_high */ 294#endif 295