1 /* SPDX-License-Identifier: GPL-2.0+ */ 2 /* 3 * U-Boot - x86 Startup Code 4 * 5 * (C) Copyright 2008-2011 6 * Graeme Russ, <graeme.russ (at) gmail.com> 7 * 8 * (C) Copyright 2002 9 * Daniel Engstrm, Omicron Ceti AB, <daniel (at) omicron.se> 10 */ 11 12 #include <config.h> 13 #include <asm/global_data.h> 14 #include <asm/post.h> 15 #include <asm/processor.h> 16 #include <asm/processor-flags.h> 17 #include <generated/generic-asm-offsets.h> 18 #include <generated/asm-offsets.h> 19 20 .section .text 21 .code32 22 .globl _start 23 .type _start, @function 24 .globl _x86boot_start 25 _x86boot_start: 26 /* 27 * This is the fail-safe 32-bit bootstrap entry point. 28 * 29 * This code is used when booting from another boot loader like 30 * coreboot or EFI. So we repeat some of the same init found in 31 * start16. 32 */ 33 cli 34 cld 35 36 /* Turn off cache (this might require a 486-class CPU) */ 37 movl %cr0, %eax 38 orl $(X86_CR0_NW | X86_CR0_CD), %eax 39 movl %eax, %cr0 40 wbinvd 41 42 /* Tell 32-bit code it is being entered from an in-RAM copy */ 43 movl $GD_FLG_WARM_BOOT, %ebx 44 45 /* 46 * Zero the BIST (Built-In Self Test) value since we don't have it. 47 * It must be 0 or the previous loader would have reported an error. 48 */ 49 movl $0, %ebp 50 51 jmp 1f 52 53 /* Add a way for tools to discover the _start entry point */ 54 .align 4 55 .long 0x12345678 56 _start: 57 /* 58 * This is the 32-bit cold-reset entry point, coming from start16. 59 * Set %ebx to GD_FLG_COLD_BOOT to indicate this. 60 */ 61 movl $GD_FLG_COLD_BOOT, %ebx 62 63 /* Save BIST */ 64 movl %eax, %ebp 65 1: 66 67 /* Save table pointer */ 68 movl %ecx, %esi 69 70 #ifdef CONFIG_X86_LOAD_FROM_32_BIT 71 lgdt gdt_ptr2 72 #endif 73 74 /* Load the segement registers to match the GDT loaded in start16.S */ 75 movl $(X86_GDT_ENTRY_32BIT_DS * X86_GDT_ENTRY_SIZE), %eax 76 movw %ax, %fs 77 movw %ax, %ds 78 movw %ax, %gs 79 movw %ax, %es 80 movw %ax, %ss 81 82 /* Clear the interrupt vectors */ 83 lidt blank_idt_ptr 84 85 /* 86 * Critical early platform init - generally not used, we prefer init 87 * to happen later when we have a console, in case something goes 88 * wrong. 89 */ 90 jmp early_board_init 91 .globl early_board_init_ret 92 early_board_init_ret: 93 post_code(POST_START) 94 95 /* Initialise Cache-As-RAM */ 96 jmp car_init 97 .globl car_init_ret 98 car_init_ret: 99 #ifndef CONFIG_HAVE_FSP 100 /* 101 * We now have CONFIG_SYS_CAR_SIZE bytes of Cache-As-RAM (or SRAM, 102 * or fully initialised SDRAM - we really don't care which) 103 * starting at CONFIG_SYS_CAR_ADDR to be used as a temporary stack 104 * and early malloc() area. The MRC requires some space at the top. 105 * 106 * Stack grows down from top of CAR. We have: 107 * 108 * top-> CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE 109 * MRC area 110 * global_data with x86 global descriptor table 111 * early malloc area 112 * stack 113 * bottom-> CONFIG_SYS_CAR_ADDR 114 */ 115 movl $(CONFIG_SYS_CAR_ADDR + CONFIG_SYS_CAR_SIZE - 4), %esp 116 #ifdef CONFIG_DCACHE_RAM_MRC_VAR_SIZE 117 subl $CONFIG_DCACHE_RAM_MRC_VAR_SIZE, %esp 118 #endif 119 #else 120 /* 121 * U-Boot enters here twice. For the first time it comes from 122 * car_init_done() with esp points to a temporary stack and esi 123 * set to zero. For the second time it comes from fsp_init_done() 124 * with esi holding the HOB list address returned by the FSP. 125 */ 126 #endif 127 /* Set up global data */ 128 mov %esp, %eax 129 call board_init_f_alloc_reserve 130 mov %eax, %esp 131 call board_init_f_init_reserve 132 133 #ifdef CONFIG_DEBUG_UART 134 call debug_uart_init 135 #endif 136 137 /* Get address of global_data */ 138 mov %fs:0, %edx 139 #ifdef CONFIG_HAVE_FSP 140 /* Store the HOB list if we have one */ 141 test %esi, %esi 142 jz skip_hob 143 movl %esi, GD_HOB_LIST(%edx) 144 145 /* 146 * After fsp_init() returns, the stack has already been switched to a 147 * place within system memory as defined by CONFIG_FSP_TEMP_RAM_ADDR. 148 * Enlarge the size of malloc() pool before relocation since we have 149 * plenty of memory now. 150 */ 151 subl $CONFIG_FSP_SYS_MALLOC_F_LEN, %esp 152 movl %esp, GD_MALLOC_BASE(%edx) 153 skip_hob: 154 #else 155 /* Store table pointer */ 156 movl %esi, GD_TABLE(%edx) 157 #endif 158 /* Store BIST */ 159 movl %ebp, GD_BIST(%edx) 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 174 board_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 /* See if we need to disable CAR */ 187 .weak car_uninit 188 movl $car_uninit, %eax 189 cmpl $0, %eax 190 jz 1f 191 192 call car_uninit 193 1: 194 /* Re-enter U-Boot by calling board_init_f_r() */ 195 call board_init_f_r 196 197 die: 198 hlt 199 jmp die 200 hlt 201 202 blank_idt_ptr: 203 .word 0 /* limit */ 204 .long 0 /* base */ 205 206 .p2align 2 /* force 4-byte alignment */ 207 208 /* Add a multiboot header so U-Boot can be loaded by GRUB2 */ 209 multiboot_header: 210 /* magic */ 211 .long 0x1badb002 212 /* flags */ 213 .long (1 << 16) 214 /* checksum */ 215 .long -0x1BADB002 - (1 << 16) 216 /* header addr */ 217 .long multiboot_header - _x86boot_start + CONFIG_SYS_TEXT_BASE 218 /* load addr */ 219 .long CONFIG_SYS_TEXT_BASE 220 /* load end addr */ 221 .long 0 222 /* bss end addr */ 223 .long 0 224 /* entry addr */ 225 .long CONFIG_SYS_TEXT_BASE 226 227 #ifdef CONFIG_X86_LOAD_FROM_32_BIT 228 /* 229 * The following Global Descriptor Table is just enough to get us into 230 * 'Flat Protected Mode' - It will be discarded as soon as the final 231 * GDT is setup in a safe location in RAM 232 */ 233 gdt_ptr2: 234 .word 0x1f /* limit (31 bytes = 4 GDT entries - 1) */ 235 .long gdt_rom2 /* base */ 236 237 /* Some CPUs are picky about GDT alignment... */ 238 .align 16 239 .globl gdt_rom2 240 gdt_rom2: 241 /* 242 * The GDT table ... 243 * 244 * Selector Type 245 * 0x00 NULL 246 * 0x08 Unused 247 * 0x10 32bit code 248 * 0x18 32bit data/stack 249 */ 250 /* The NULL Desciptor - Mandatory */ 251 .word 0x0000 /* limit_low */ 252 .word 0x0000 /* base_low */ 253 .byte 0x00 /* base_middle */ 254 .byte 0x00 /* access */ 255 .byte 0x00 /* flags + limit_high */ 256 .byte 0x00 /* base_high */ 257 258 /* Unused Desciptor - (matches Linux) */ 259 .word 0x0000 /* limit_low */ 260 .word 0x0000 /* base_low */ 261 .byte 0x00 /* base_middle */ 262 .byte 0x00 /* access */ 263 .byte 0x00 /* flags + limit_high */ 264 .byte 0x00 /* base_high */ 265 266 /* 267 * The Code Segment Descriptor: 268 * - Base = 0x00000000 269 * - Size = 4GB 270 * - Access = Present, Ring 0, Exec (Code), Readable 271 * - Flags = 4kB Granularity, 32-bit 272 */ 273 .word 0xffff /* limit_low */ 274 .word 0x0000 /* base_low */ 275 .byte 0x00 /* base_middle */ 276 .byte 0x9b /* access */ 277 .byte 0xcf /* flags + limit_high */ 278 .byte 0x00 /* base_high */ 279 280 /* 281 * The Data Segment Descriptor: 282 * - Base = 0x00000000 283 * - Size = 4GB 284 * - Access = Present, Ring 0, Non-Exec (Data), Writable 285 * - Flags = 4kB Granularity, 32-bit 286 */ 287 .word 0xffff /* limit_low */ 288 .word 0x0000 /* base_low */ 289 .byte 0x00 /* base_middle */ 290 .byte 0x93 /* access */ 291 .byte 0xcf /* flags + limit_high */ 292 .byte 0x00 /* base_high */ 293 #endif 294
