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 66 1: 67 68 /* Save table pointer */ 69 movl %ecx, %esi 70 71 /* Load the segement registers to match the GDT loaded in start16.S */ 72 movl $(X86_GDT_ENTRY_32BIT_DS * X86_GDT_ENTRY_SIZE), %eax 73 movw %ax, %fs 74 movw %ax, %ds 75 movw %ax, %gs 76 movw %ax, %es 77 movw %ax, %ss 78 79 /* Clear the interrupt vectors */ 80 lidt blank_idt_ptr 81 82 /* 83 * Critical early platform init - generally not used, we prefer init 84 * to happen later when we have a console, in case something goes 85 * wrong. 86 */ 87 jmp early_board_init 88 .globl early_board_init_ret 89 early_board_init_ret: 90 post_code(POST_START) 91 92 /* Initialise Cache-As-RAM */ 93 jmp car_init 94 .globl car_init_ret 95 car_init_ret: 96 #ifndef CONFIG_HAVE_FSP 97 /* 98 * We now have CONFIG_SYS_CAR_SIZE bytes of Cache-As-RAM (or SRAM, 99 * or fully initialised SDRAM - we really don't care which) 100 * starting at CONFIG_SYS_CAR_ADDR to be used as a temporary stack 101 * and early malloc() area. The MRC requires some space at the top. 102 * 103 * Stack grows down from top of CAR. We have: 104 * 105 * top-> CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE 106 * MRC area 107 * global_data with x86 global descriptor table 108 * early malloc area 109 * stack 110 * bottom-> CONFIG_SYS_CAR_ADDR 111 */ 112 movl $(CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE - 4), %esp 113 #ifdef CONFIG_DCACHE_RAM_MRC_VAR_SIZE 114 subl $CONFIG_DCACHE_RAM_MRC_VAR_SIZE, %esp 115 #endif 116 #else 117 /* 118 * U-Boot enters here twice. For the first time it comes from 119 * car_init_done() with esp points to a temporary stack and esi 120 * set to zero. For the second time it comes from fsp_init_done() 121 * with esi holding the HOB list address returned by the FSP. 122 */ 123 #endif 124 /* Set up global data */ 125 mov %esp, %eax 126 call board_init_f_alloc_reserve 127 mov %eax, %esp 128 call board_init_f_init_reserve 129 130 #ifdef CONFIG_DEBUG_UART 131 call debug_uart_init 132 #endif 133 134 /* Get address of global_data */ 135 mov %fs:0, %edx 136 #ifdef CONFIG_HAVE_FSP 137 /* Store the HOB list if we have one */ 138 test %esi, %esi 139 jz skip_hob 140 movl %esi, GD_HOB_LIST(%edx) 141 142 /* 143 * After fsp_init() returns, the stack has already been switched to a 144 * place within system memory as defined by CONFIG_FSP_TEMP_RAM_ADDR. 145 * Enlarge the size of malloc() pool before relocation since we have 146 * plenty of memory now. 147 */ 148 subl $CONFIG_FSP_SYS_MALLOC_F_LEN, %esp 149 movl %esp, GD_MALLOC_BASE(%edx) 150 skip_hob: 151 #else 152 /* Store table pointer */ 153 movl %esi, GD_TABLE(%edx) 154 #endif 155 /* Store BIST */ 156 movl %ebp, GD_BIST(%edx) 157 158 /* Set parameter to board_init_f() to boot flags */ 159 post_code(POST_START_DONE) 160 xorl %eax, %eax 161 162 /* Enter, U-Boot! */ 163 call board_init_f 164 165 /* indicate (lack of) progress */ 166 movw $0x85, %ax 167 jmp die 168 169 .globl board_init_f_r_trampoline 170 .type board_init_f_r_trampoline, @function 171 board_init_f_r_trampoline: 172 /* 173 * SDRAM has been initialised, U-Boot code has been copied into 174 * RAM, BSS has been cleared and relocation adjustments have been 175 * made. It is now time to jump into the in-RAM copy of U-Boot 176 * 177 * %eax = Address of top of new stack 178 */ 179 180 /* Stack grows down from top of SDRAM */ 181 movl %eax, %esp 182 183 /* See if we need to disable CAR */ 184 .weak car_uninit 185 movl $car_uninit, %eax 186 cmpl $0, %eax 187 jz 1f 188 189 call car_uninit 190 1: 191 /* Re-enter U-Boot by calling board_init_f_r() */ 192 call board_init_f_r 193 194 die: 195 hlt 196 jmp die 197 hlt 198 199 blank_idt_ptr: 200 .word 0 /* limit */ 201 .long 0 /* base */ 202 203 .p2align 2 /* force 4-byte alignment */ 204 205 /* Add a multiboot header so U-Boot can be loaded by GRUB2 */ 206 multiboot_header: 207 /* magic */ 208 .long 0x1badb002 209 /* flags */ 210 .long (1 << 16) 211 /* checksum */ 212 .long -0x1BADB002 - (1 << 16) 213 /* header addr */ 214 .long multiboot_header - _x86boot_start + CONFIG_SYS_TEXT_BASE 215 /* load addr */ 216 .long CONFIG_SYS_TEXT_BASE 217 /* load end addr */ 218 .long 0 219 /* bss end addr */ 220 .long 0 221 /* entry addr */ 222 .long CONFIG_SYS_TEXT_BASE 223