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@gmail.com> 7 * 8 * (C) Copyright 2002 9 * Daniel Engström, Omicron Ceti AB, <daniel@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 #include <linux/linkage.h> 20 21 .section .text.start 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 #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 93 early_board_init_ret: 94 post_code(POST_START) 95 96 /* Initialise Cache-As-RAM */ 97 jmp car_init 98 .globl car_init_ret 99 car_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) 154 skip_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 175 board_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 call car_uninit 189 190 /* Re-enter U-Boot by calling board_init_f_r() */ 191 call board_init_f_r 192 193 die: 194 hlt 195 jmp die 196 hlt 197 198 WEAK(car_uninit) 199 ret 200 ENDPROC(car_uninit) 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